libsemanage: Perform access check using euid instead of uid v2

libsemanage: Perform access check using euid instead of uid v2

[Vit Mojzis]

Changes: 
  - replace semanage_copy_file by copy_file_if_exists to make sure "retval" is 0 if the file does not exist
  - restructure if statements to be more clear ("fail" is last part of the statement)
  - replace read test (attempt to open the file) by stat() call

[PATCH 1/3] libsemanage: remove access() check to make setuid programs work

[Vit Mojzis]

access() uses real UID instead of effective UID which causes false
negative checks in setuid programs. Remove redundant access() checks

Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1186431

Signed-off-by: Vit Mojzis <vmojzis@redhat.com>
---
 libsemanage/src/direct_api.c     |  7 -------
 libsemanage/src/semanage_store.c | 17 ++++++++---------
 2 files changed, 8 insertions(+), 16 deletions(-)

diff --git a/libsemanage/src/direct_api.c b/libsemanage/src/direct_api.c
index 88873c43..b7899d68 100644
--- a/libsemanage/src/direct_api.c
+++ b/libsemanage/src/direct_api.c
@@ -148,9 +148,6 @@ int semanage_direct_connect(semanage_handle_t * sh)
 		if (semanage_create_store(sh, 1))
 			goto err;
 
-	if (semanage_access_check(sh) < SEMANAGE_CAN_READ)
-		goto err;
-
 	sh->u.direct.translock_file_fd = -1;
 	sh->u.direct.activelock_file_fd = -1;
 
@@ -398,10 +395,6 @@ static int semanage_direct_disconnect(semanage_handle_t *sh)
 
 static int semanage_direct_begintrans(semanage_handle_t * sh)
 {
-
-	if (semanage_access_check(sh) != SEMANAGE_CAN_WRITE) {
-		return -1;
-	}
 	if (semanage_get_trans_lock(sh) < 0) {
 		return -1;
 	}
diff --git a/libsemanage/src/semanage_store.c b/libsemanage/src/semanage_store.c
index 936e6495..4bd1d651 100644
--- a/libsemanage/src/semanage_store.c
+++ b/libsemanage/src/semanage_store.c
@@ -538,7 +538,6 @@ char *semanage_conf_path(void)
 int semanage_create_store(semanage_handle_t * sh, int create)
 {
 	struct stat sb;
-	int mode_mask = R_OK | W_OK | X_OK;
 	const char *path = semanage_files[SEMANAGE_ROOT];
 	int fd;
 
@@ -557,9 +556,9 @@ int semanage_create_store(semanage_handle_t * sh, int create)
 			return -1;
 		}
 	} else {
-		if (!S_ISDIR(sb.st_mode) || access(path, mode_mask) == -1) {
+		if (!S_ISDIR(sb.st_mode)) {
 			ERR(sh,
-			    "Could not access module store at %s, or it is not a directory.",
+			    "Module store at %s is not a directory.",
 			    path);
 			return -1;
 		}
@@ -580,9 +579,9 @@ int semanage_create_store(semanage_handle_t * sh, int create)
 			return -1;
 		}
 	} else {
-		if (!S_ISDIR(sb.st_mode) || access(path, mode_mask) == -1) {
+		if (!S_ISDIR(sb.st_mode)) {
 			ERR(sh,
-			    "Could not access module store active subdirectory at %s, or it is not a directory.",
+			    "Module store active subdirectory at %s is not a directory.",
 			    path);
 			return -1;
 		}
@@ -603,9 +602,9 @@ int semanage_create_store(semanage_handle_t * sh, int create)
 			return -1;
 		}
 	} else {
-		if (!S_ISDIR(sb.st_mode) || access(path, mode_mask) == -1) {
+		if (!S_ISDIR(sb.st_mode)) {
 			ERR(sh,
-			    "Could not access module store active modules subdirectory at %s, or it is not a directory.",
+			    "Module store active modules subdirectory at %s is not a directory.",
 			    path);
 			return -1;
 		}
@@ -624,8 +623,8 @@ int semanage_create_store(semanage_handle_t * sh, int create)
 			return -1;
 		}
 	} else {
-		if (!S_ISREG(sb.st_mode) || access(path, R_OK | W_OK) == -1) {
-			ERR(sh, "Could not access lock file at %s.", path);
+		if (!S_ISREG(sb.st_mode)) {
+			ERR(sh, "Object at %s is not a lock file.", path);
 			return -1;
 		}
 	}
-- 
2.14.3

[PATCH 2/3] libsemanage: remove access() check to make setuid programs work

[Vit Mojzis]

F_OK access checks only work properly as long as all directories along
the path are accessible to real user running the program.
Replace F_OK access checks by testing return value of open, write, etc.

Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1186431

Signed-off-by: Vit Mojzis <vmojzis@redhat.com>
---
 libsemanage/src/direct_api.c | 47 ++++++++++++++++++++++----------------------
 1 file changed, 23 insertions(+), 24 deletions(-)

diff --git a/libsemanage/src/direct_api.c b/libsemanage/src/direct_api.c
index b7899d68..49cac14f 100644
--- a/libsemanage/src/direct_api.c
+++ b/libsemanage/src/direct_api.c
@@ -1171,6 +1171,14 @@ cleanup:
 	return status;
 }
 
+/* Copies a file from src to dst. If dst already exists then
+ * overwrite it. If source doesn't exist then return success.
+ * Returns 0 on success, -1 on error. */
+static int copy_file_if_exists(const char *src, const char *dst, mode_t mode){
+	int rc = semanage_copy_file(src, dst, mode);
+	return (rc < 0 && errno != ENOENT) ? rc : 0;
+}
+
 /********************* direct API functions ********************/
 
 /* Commits all changes in sandbox to the actual kernel policy.
@@ -1563,34 +1571,25 @@ rebuild:
 		goto cleanup;
 	}
 
-	path = semanage_path(SEMANAGE_TMP, SEMANAGE_STORE_FC_LOCAL);
-	if (access(path, F_OK) == 0) {
-		retval = semanage_copy_file(semanage_path(SEMANAGE_TMP, SEMANAGE_STORE_FC_LOCAL),
-							semanage_final_path(SEMANAGE_FINAL_TMP, SEMANAGE_FC_LOCAL),
-							sh->conf->file_mode);
-		if (retval < 0) {
-			goto cleanup;
-		}
+	retval = copy_file_if_exists(semanage_path(SEMANAGE_TMP, SEMANAGE_STORE_FC_LOCAL),
+						semanage_final_path(SEMANAGE_FINAL_TMP, SEMANAGE_FC_LOCAL),
+						sh->conf->file_mode);
+	if (retval < 0) {
+		goto cleanup;
 	}
 
-	path = semanage_path(SEMANAGE_TMP, SEMANAGE_STORE_FC);
-	if (access(path, F_OK) == 0) {
-		retval = semanage_copy_file(semanage_path(SEMANAGE_TMP, SEMANAGE_STORE_FC),
-							semanage_final_path(SEMANAGE_FINAL_TMP, SEMANAGE_FC),
-							sh->conf->file_mode);
-		if (retval < 0) {
-			goto cleanup;
-		}
+	retval = copy_file_if_exists(semanage_path(SEMANAGE_TMP, SEMANAGE_STORE_FC),
+						semanage_final_path(SEMANAGE_FINAL_TMP, SEMANAGE_FC),
+						sh->conf->file_mode);
+	if (retval < 0) {
+		goto cleanup;
 	}
 
-	path = semanage_path(SEMANAGE_TMP, SEMANAGE_STORE_SEUSERS);
-	if (access(path, F_OK) == 0) {
-		retval = semanage_copy_file(semanage_path(SEMANAGE_TMP, SEMANAGE_STORE_SEUSERS),
-							semanage_final_path(SEMANAGE_FINAL_TMP, SEMANAGE_SEUSERS),
-							sh->conf->file_mode);
-		if (retval < 0) {
-			goto cleanup;
-		}
+	retval = copy_file_if_exists(semanage_path(SEMANAGE_TMP, SEMANAGE_STORE_SEUSERS),
+						semanage_final_path(SEMANAGE_FINAL_TMP, SEMANAGE_SEUSERS),
+						sh->conf->file_mode);
+	if (retval < 0) {
+		goto cleanup;
 	}
 
 	/* run genhomedircon if its enabled, this should be the last operation
-- 
2.14.3

Re: [PATCH 2/3] libsemanage: remove access() check to make setuid programs work

[Stephen Smalley]

On 03/06/2018 06:58 AM, Vit Mojzis wrote:
> F_OK access checks only work properly as long as all directories along
> the path are accessible to real user running the program.
> Replace F_OK access checks by testing return value of open, write, etc.

Applied patches 1 and 2 (not 3 as per my comments).

> 
> Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1186431
> 
> Signed-off-by: Vit Mojzis <vmojzis@redhat.com>
> ---
>  libsemanage/src/direct_api.c | 47 ++++++++++++++++++++++----------------------
>  1 file changed, 23 insertions(+), 24 deletions(-)
> 
> diff --git a/libsemanage/src/direct_api.c b/libsemanage/src/direct_api.c
> index b7899d68..49cac14f 100644
> --- a/libsemanage/src/direct_api.c
> +++ b/libsemanage/src/direct_api.c
> @@ -1171,6 +1171,14 @@ cleanup:
>  	return status;
>  }
>  
> +/* Copies a file from src to dst. If dst already exists then
> + * overwrite it. If source doesn't exist then return success.
> + * Returns 0 on success, -1 on error. */
> +static int copy_file_if_exists(const char *src, const char *dst, mode_t mode){
> +	int rc = semanage_copy_file(src, dst, mode);
> +	return (rc < 0 && errno != ENOENT) ? rc : 0;
> +}
> +
>  /********************* direct API functions ********************/
>  
>  /* Commits all changes in sandbox to the actual kernel policy.
> @@ -1563,34 +1571,25 @@ rebuild:
>  		goto cleanup;
>  	}
>  
> -	path = semanage_path(SEMANAGE_TMP, SEMANAGE_STORE_FC_LOCAL);
> -	if (access(path, F_OK) == 0) {
> -		retval = semanage_copy_file(semanage_path(SEMANAGE_TMP, SEMANAGE_STORE_FC_LOCAL),
> -							semanage_final_path(SEMANAGE_FINAL_TMP, SEMANAGE_FC_LOCAL),
> -							sh->conf->file_mode);
> -		if (retval < 0) {
> -			goto cleanup;
> -		}
> +	retval = copy_file_if_exists(semanage_path(SEMANAGE_TMP, SEMANAGE_STORE_FC_LOCAL),
> +						semanage_final_path(SEMANAGE_FINAL_TMP, SEMANAGE_FC_LOCAL),
> +						sh->conf->file_mode);
> +	if (retval < 0) {
> +		goto cleanup;
>  	}
>  
> -	path = semanage_path(SEMANAGE_TMP, SEMANAGE_STORE_FC);
> -	if (access(path, F_OK) == 0) {
> -		retval = semanage_copy_file(semanage_path(SEMANAGE_TMP, SEMANAGE_STORE_FC),
> -							semanage_final_path(SEMANAGE_FINAL_TMP, SEMANAGE_FC),
> -							sh->conf->file_mode);
> -		if (retval < 0) {
> -			goto cleanup;
> -		}
> +	retval = copy_file_if_exists(semanage_path(SEMANAGE_TMP, SEMANAGE_STORE_FC),
> +						semanage_final_path(SEMANAGE_FINAL_TMP, SEMANAGE_FC),
> +						sh->conf->file_mode);
> +	if (retval < 0) {
> +		goto cleanup;
>  	}
>  
> -	path = semanage_path(SEMANAGE_TMP, SEMANAGE_STORE_SEUSERS);
> -	if (access(path, F_OK) == 0) {
> -		retval = semanage_copy_file(semanage_path(SEMANAGE_TMP, SEMANAGE_STORE_SEUSERS),
> -							semanage_final_path(SEMANAGE_FINAL_TMP, SEMANAGE_SEUSERS),
> -							sh->conf->file_mode);
> -		if (retval < 0) {
> -			goto cleanup;
> -		}
> +	retval = copy_file_if_exists(semanage_path(SEMANAGE_TMP, SEMANAGE_STORE_SEUSERS),
> +						semanage_final_path(SEMANAGE_FINAL_TMP, SEMANAGE_SEUSERS),
> +						sh->conf->file_mode);
> +	if (retval < 0) {
> +		goto cleanup;
>  	}
>  
>  	/* run genhomedircon if its enabled, this should be the last operation
> 

[PATCH 3/3] libsemanage: replace access() checks to make setuid programs work

[Vit Mojzis]

access() uses real UID instead of effective UID which causes false
negative checks in setuid programs.
Replace access(,F_OK) (i.e. tests for file existence) by stat().
And access(,R_OK) by fopen(,"r")

Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1186431

Signed-off-by: Vit Mojzis <vmojzis@redhat.com>
---
 libsemanage/src/direct_api.c     | 133 +++++++++++++++++++++++++--------------
 libsemanage/src/semanage_store.c |  16 ++++-
 2 files changed, 99 insertions(+), 50 deletions(-)

diff --git a/libsemanage/src/direct_api.c b/libsemanage/src/direct_api.c
index 49cac14f..4e2af810 100644
--- a/libsemanage/src/direct_api.c
+++ b/libsemanage/src/direct_api.c
@@ -140,6 +140,7 @@ int semanage_direct_is_managed(semanage_handle_t * sh)
 int semanage_direct_connect(semanage_handle_t * sh)
 {
 	const char *path;
+	struct stat sb;
 
 	if (semanage_check_init(sh, sh->conf->store_root_path))
 		goto err;
@@ -302,10 +303,16 @@ int semanage_direct_connect(semanage_handle_t * sh)
 
 	/* set the disable dontaudit value */
 	path = semanage_path(SEMANAGE_ACTIVE, SEMANAGE_DISABLE_DONTAUDIT);
-	if (access(path, F_OK) == 0)
+
+	if (stat(path, &sb) == 0)
 		sepol_set_disable_dontaudit(sh->sepolh, 1);
-	else
+	else if (errno == ENOENT) {
+		/* The file does not exist */
 		sepol_set_disable_dontaudit(sh->sepolh, 0);
+	} else {
+		ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
+		goto err;
+	}
 
 	return STATUS_SUCCESS;
 
@@ -1139,6 +1146,7 @@ static int semanage_compile_hll_modules(semanage_handle_t *sh,
 	int status = 0;
 	int i;
 	char cil_path[PATH_MAX];
+	struct stat sb;
 
 	assert(sh);
 	assert(modinfos);
@@ -1155,9 +1163,13 @@ static int semanage_compile_hll_modules(semanage_handle_t *sh,
 		}
 
 		if (semanage_get_ignore_module_cache(sh) == 0 &&
-				access(cil_path, F_OK) == 0) {
+				(status = stat(cil_path, &sb)) == 0) {
 			continue;
 		}
+		if (status != 0 && errno != ENOENT) {
+			ERR(sh, "Unable to access %s: %s\n", cil_path, strerror(errno));
+			goto cleanup; //an error in the "stat" call
+		}
 
 		status = semanage_compile_module(sh, &modinfos[i]);
 		if (status < 0) {
@@ -1196,6 +1208,7 @@ static int semanage_direct_commit(semanage_handle_t * sh)
 	struct cil_db *cildb = NULL;
 	semanage_module_info_t *modinfos = NULL;
 	mode_t mask = umask(0077);
+	struct stat sb;
 
 	int do_rebuild, do_write_kernel, do_install;
 	int fcontexts_modified, ports_modified, seusers_modified,
@@ -1234,10 +1247,15 @@ static int semanage_direct_commit(semanage_handle_t * sh)
 
 	/* Create or remove the disable_dontaudit flag file. */
 	path = semanage_path(SEMANAGE_TMP, SEMANAGE_DISABLE_DONTAUDIT);
-	if (access(path, F_OK) == 0)
+	if (stat(path, &sb) == 0)
 		do_rebuild |= !(sepol_get_disable_dontaudit(sh->sepolh) == 1);
-	else
+	else if (errno == ENOENT) {
+		/* The file does not exist */
 		do_rebuild |= (sepol_get_disable_dontaudit(sh->sepolh) == 1);
+	} else {
+		ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
+		goto cleanup;
+	}
 	if (sepol_get_disable_dontaudit(sh->sepolh) == 1) {
 		FILE *touch;
 		touch = fopen(path, "w");
@@ -1259,10 +1277,16 @@ static int semanage_direct_commit(semanage_handle_t * sh)
 
 	/* Create or remove the preserve_tunables flag file. */
 	path = semanage_path(SEMANAGE_TMP, SEMANAGE_PRESERVE_TUNABLES);
-	if (access(path, F_OK) == 0)
+	if (stat(path, &sb) == 0)
 		do_rebuild |= !(sepol_get_preserve_tunables(sh->sepolh) == 1);
-	else
+	else if (errno == ENOENT) {
+		/* The file does not exist */
 		do_rebuild |= (sepol_get_preserve_tunables(sh->sepolh) == 1);
+	} else {
+		ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
+		goto cleanup;
+	}
+
 	if (sepol_get_preserve_tunables(sh->sepolh) == 1) {
 		FILE *touch;
 		touch = fopen(path, "w");
@@ -1299,40 +1323,24 @@ static int semanage_direct_commit(semanage_handle_t * sh)
 	 * a rebuild.
 	 */
 	if (!do_rebuild) {
-		path = semanage_path(SEMANAGE_TMP, SEMANAGE_STORE_KERNEL);
-		if (access(path, F_OK) != 0) {
-			do_rebuild = 1;
-			goto rebuild;
-		}
-
-		path = semanage_path(SEMANAGE_TMP, SEMANAGE_STORE_FC);
-		if (access(path, F_OK) != 0) {
-			do_rebuild = 1;
-			goto rebuild;
-		}
-
-		path = semanage_path(SEMANAGE_TMP, SEMANAGE_STORE_SEUSERS);
-		if (access(path, F_OK) != 0) {
-			do_rebuild = 1;
-			goto rebuild;
-		}
-
-		path = semanage_path(SEMANAGE_TMP, SEMANAGE_LINKED);
-		if (access(path, F_OK) != 0) {
-			do_rebuild = 1;
-			goto rebuild;
-		}
-
-		path = semanage_path(SEMANAGE_TMP, SEMANAGE_SEUSERS_LINKED);
-		if (access(path, F_OK) != 0) {
-			do_rebuild = 1;
-			goto rebuild;
-		}
+		int files[] = {SEMANAGE_STORE_KERNEL,
+					   SEMANAGE_STORE_FC,
+					   SEMANAGE_STORE_SEUSERS,
+					   SEMANAGE_LINKED,
+					   SEMANAGE_SEUSERS_LINKED,
+					   SEMANAGE_USERS_EXTRA_LINKED};
+
+		for (i = 0; i < (int) sizeof(files); i++) {
+			path = semanage_path(SEMANAGE_TMP, files[i]);
+			if (stat(path, &sb) != 0) {
+				if (errno != ENOENT) {
+					ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
+					goto cleanup;
+				}
 
-		path = semanage_path(SEMANAGE_TMP, SEMANAGE_USERS_EXTRA_LINKED);
-		if (access(path, F_OK) != 0) {
-			do_rebuild = 1;
-			goto rebuild;
+				do_rebuild = 1;
+				goto rebuild;
+			}
 		}
 	}
 
@@ -1465,7 +1473,7 @@ rebuild:
 			goto cleanup;
 
 		path = semanage_path(SEMANAGE_TMP, SEMANAGE_SEUSERS_LINKED);
-		if (access(path, F_OK) == 0) {
+		if (stat(path, &sb) == 0) {
 			retval = semanage_copy_file(path,
 						    semanage_path(SEMANAGE_TMP,
 								  SEMANAGE_STORE_SEUSERS),
@@ -1473,12 +1481,18 @@ rebuild:
 			if (retval < 0)
 				goto cleanup;
 			pseusers->dtable->drop_cache(pseusers->dbase);
-		} else {
+		} else if (errno == ENOENT) {
+			/* The file does not exist */
 			pseusers->dtable->clear(sh, pseusers->dbase);
+		} else {
+			ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
+			goto cleanup;
 		}
 
+
+
 		path = semanage_path(SEMANAGE_TMP, SEMANAGE_USERS_EXTRA_LINKED);
-		if (access(path, F_OK) == 0) {
+		if (stat(path, &sb) == 0) {
 			retval = semanage_copy_file(path,
 						    semanage_path(SEMANAGE_TMP,
 								  SEMANAGE_USERS_EXTRA),
@@ -1486,8 +1500,12 @@ rebuild:
 			if (retval < 0)
 				goto cleanup;
 			pusers_extra->dtable->drop_cache(pusers_extra->dbase);
-		} else {
+		} else if (errno == ENOENT) {
+			/* The file does not exist */
 			pusers_extra->dtable->clear(sh, pusers_extra->dbase);
+		} else {
+			ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
+			goto cleanup;
 		}
 	}
 
@@ -1817,6 +1835,7 @@ static int semanage_direct_extract(semanage_handle_t * sh,
 	ssize_t _data_len;
 	char *_data;
 	int compressed;
+	struct stat sb;
 
 	/* get path of module */
 	rc = semanage_module_get_path(
@@ -1829,8 +1848,8 @@ static int semanage_direct_extract(semanage_handle_t * sh,
 		goto cleanup;
 	}
 
-	if (access(module_path, F_OK) != 0) {
-		ERR(sh, "Module does not exist: %s", module_path);
+	if (stat(module_path, &sb) != 0) {
+		ERR(sh, "Unable to access %s: %s\n", module_path, strerror(errno));
 		rc = -1;
 		goto cleanup;
 	}
@@ -1859,7 +1878,12 @@ static int semanage_direct_extract(semanage_handle_t * sh,
 		goto cleanup;
 	}
 
-	if (extract_cil == 1 && strcmp(_modinfo->lang_ext, "cil") && access(input_file, F_OK) != 0) {
+	if (extract_cil == 1 && strcmp(_modinfo->lang_ext, "cil") && stat(input_file, &sb) != 0) {
+		if (errno != ENOENT) {
+			ERR(sh, "Unable to access %s: %s\n", input_file, strerror(errno));
+			goto cleanup;
+		}
+
 		rc = semanage_compile_module(sh, _modinfo);
 		if (rc < 0) {
 			goto cleanup;
@@ -2004,6 +2028,12 @@ static int semanage_direct_get_enabled(semanage_handle_t *sh,
 	}
 
 	if (stat(path, &sb) < 0) {
+		if (errno != ENOENT) {
+			ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
+			status = -1;
+			goto cleanup;
+		}
+
 		*enabled = 1;
 	}
 	else {
@@ -2330,6 +2360,12 @@ static int semanage_direct_get_module_info(semanage_handle_t *sh,
 
 	/* set enabled/disabled status */
 	if (stat(fn, &sb) < 0) {
+		if (errno != ENOENT) {
+			ERR(sh, "Unable to access %s: %s\n", fn, strerror(errno));
+			status = -1;
+			goto cleanup;
+		}
+
 		ret = semanage_module_info_set_enabled(sh, *modinfo, 1);
 		if (ret != 0) {
 			status = -1;
@@ -2738,6 +2774,7 @@ static int semanage_direct_install_info(semanage_handle_t *sh,
 	int status = 0;
 	int ret = 0;
 	int type;
+	struct stat sb;
 
 	char path[PATH_MAX];
 	mode_t mask = umask(0077);
@@ -2838,7 +2875,7 @@ static int semanage_direct_install_info(semanage_handle_t *sh,
 			goto cleanup;
 		}
 
-		if (access(path, F_OK) == 0) {
+		if (stat(path, &sb) == 0) {
 			ret = unlink(path);
 			if (ret != 0) {
 				ERR(sh, "Error while removing cached CIL file %s: %s", path, strerror(errno));
diff --git a/libsemanage/src/semanage_store.c b/libsemanage/src/semanage_store.c
index 4bd1d651..10f8b306 100644
--- a/libsemanage/src/semanage_store.c
+++ b/libsemanage/src/semanage_store.c
@@ -514,6 +514,7 @@ char *semanage_conf_path(void)
 {
 	char *semanage_conf = NULL;
 	int len;
+	struct stat sb;
 
 	len = strlen(semanage_root()) + strlen(selinux_path()) + strlen(SEMANAGE_CONF_FILE);
 	semanage_conf = calloc(len + 1, sizeof(char));
@@ -522,7 +523,12 @@ char *semanage_conf_path(void)
 	snprintf(semanage_conf, len + 1, "%s%s%s", semanage_root(), selinux_path(),
 		 SEMANAGE_CONF_FILE);
 
-	if (access(semanage_conf, R_OK) != 0) {
+	if (stat(semanage_conf, &sb) != 0) {
+		if (errno != ENOENT) {
+			/* semanage_conf exists but can't be accessed */
+			return NULL;
+		}
+
 		snprintf(semanage_conf, len + 1, "%s%s", selinux_path(), SEMANAGE_CONF_FILE);
 	}
 
@@ -1508,8 +1514,14 @@ int semanage_split_fc(semanage_handle_t * sh)
 static int sefcontext_compile(semanage_handle_t * sh, const char *path) {
 
 	int r;
+	struct stat sb;
+
+	if (stat(path, &sb) < 0) {
+		if (errno != ENOENT) {
+			ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
+			return -1;
+		}
 
-	if (access(path, F_OK) != 0) {
 		return 0;
 	}
 
-- 
2.14.3

Re: [PATCH 3/3] libsemanage: replace access() checks to make setuid programs work

[Stephen Smalley]

On 03/06/2018 06:58 AM, Vit Mojzis wrote:
> access() uses real UID instead of effective UID which causes false
> negative checks in setuid programs.
> Replace access(,F_OK) (i.e. tests for file existence) by stat().
> And access(,R_OK) by fopen(,"r")
> 
> Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1186431
> 
> Signed-off-by: Vit Mojzis <vmojzis@redhat.com>
> ---
>  libsemanage/src/direct_api.c     | 133 +++++++++++++++++++++++++--------------
>  libsemanage/src/semanage_store.c |  16 ++++-
>  2 files changed, 99 insertions(+), 50 deletions(-)
> 
> diff --git a/libsemanage/src/direct_api.c b/libsemanage/src/direct_api.c
> index 49cac14f..4e2af810 100644
> --- a/libsemanage/src/direct_api.c
> +++ b/libsemanage/src/direct_api.c
> @@ -140,6 +140,7 @@ int semanage_direct_is_managed(semanage_handle_t * sh)
>  int semanage_direct_connect(semanage_handle_t * sh)
>  {
>  	const char *path;
> +	struct stat sb;
>  
>  	if (semanage_check_init(sh, sh->conf->store_root_path))
>  		goto err;
> @@ -302,10 +303,16 @@ int semanage_direct_connect(semanage_handle_t * sh)
>  
>  	/* set the disable dontaudit value */
>  	path = semanage_path(SEMANAGE_ACTIVE, SEMANAGE_DISABLE_DONTAUDIT);
> -	if (access(path, F_OK) == 0)
> +
> +	if (stat(path, &sb) == 0)
>  		sepol_set_disable_dontaudit(sh->sepolh, 1);
> -	else
> +	else if (errno == ENOENT) {
> +		/* The file does not exist */
>  		sepol_set_disable_dontaudit(sh->sepolh, 0);
> +	} else {
> +		ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
> +		goto err;
> +	}
>  
>  	return STATUS_SUCCESS;
>  
> @@ -1139,6 +1146,7 @@ static int semanage_compile_hll_modules(semanage_handle_t *sh,
>  	int status = 0;
>  	int i;
>  	char cil_path[PATH_MAX];
> +	struct stat sb;
>  
>  	assert(sh);
>  	assert(modinfos);
> @@ -1155,9 +1163,13 @@ static int semanage_compile_hll_modules(semanage_handle_t *sh,
>  		}
>  
>  		if (semanage_get_ignore_module_cache(sh) == 0 &&
> -				access(cil_path, F_OK) == 0) {
> +				(status = stat(cil_path, &sb)) == 0) {
>  			continue;
>  		}
> +		if (status != 0 && errno != ENOENT) {
> +			ERR(sh, "Unable to access %s: %s\n", cil_path, strerror(errno));
> +			goto cleanup; //an error in the "stat" call
> +		}
>  
>  		status = semanage_compile_module(sh, &modinfos[i]);
>  		if (status < 0) {
> @@ -1196,6 +1208,7 @@ static int semanage_direct_commit(semanage_handle_t * sh)
>  	struct cil_db *cildb = NULL;
>  	semanage_module_info_t *modinfos = NULL;
>  	mode_t mask = umask(0077);
> +	struct stat sb;
>  
>  	int do_rebuild, do_write_kernel, do_install;
>  	int fcontexts_modified, ports_modified, seusers_modified,
> @@ -1234,10 +1247,15 @@ static int semanage_direct_commit(semanage_handle_t * sh)
>  
>  	/* Create or remove the disable_dontaudit flag file. */
>  	path = semanage_path(SEMANAGE_TMP, SEMANAGE_DISABLE_DONTAUDIT);
> -	if (access(path, F_OK) == 0)
> +	if (stat(path, &sb) == 0)
>  		do_rebuild |= !(sepol_get_disable_dontaudit(sh->sepolh) == 1);
> -	else
> +	else if (errno == ENOENT) {
> +		/* The file does not exist */
>  		do_rebuild |= (sepol_get_disable_dontaudit(sh->sepolh) == 1);
> +	} else {
> +		ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));

We need to ensure that retval is set in all of these cases.  Safest to always set it before goto cleanup,
either explicitly to -1 or to return value of stat() call above.

> +		goto cleanup;
> +	}
>  	if (sepol_get_disable_dontaudit(sh->sepolh) == 1) {
>  		FILE *touch;
>  		touch = fopen(path, "w");
> @@ -1259,10 +1277,16 @@ static int semanage_direct_commit(semanage_handle_t * sh)
>  
>  	/* Create or remove the preserve_tunables flag file. */
>  	path = semanage_path(SEMANAGE_TMP, SEMANAGE_PRESERVE_TUNABLES);
> -	if (access(path, F_OK) == 0)
> +	if (stat(path, &sb) == 0)
>  		do_rebuild |= !(sepol_get_preserve_tunables(sh->sepolh) == 1);
> -	else
> +	else if (errno == ENOENT) {
> +		/* The file does not exist */
>  		do_rebuild |= (sepol_get_preserve_tunables(sh->sepolh) == 1);
> +	} else {
> +		ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
> +		goto cleanup;
> +	}

Ditto

> +
>  	if (sepol_get_preserve_tunables(sh->sepolh) == 1) {
>  		FILE *touch;
>  		touch = fopen(path, "w");
> @@ -1299,40 +1323,24 @@ static int semanage_direct_commit(semanage_handle_t * sh)
>  	 * a rebuild.
>  	 */
>  	if (!do_rebuild) {
> -		path = semanage_path(SEMANAGE_TMP, SEMANAGE_STORE_KERNEL);
> -		if (access(path, F_OK) != 0) {
> -			do_rebuild = 1;
> -			goto rebuild;
> -		}
> -
> -		path = semanage_path(SEMANAGE_TMP, SEMANAGE_STORE_FC);
> -		if (access(path, F_OK) != 0) {
> -			do_rebuild = 1;
> -			goto rebuild;
> -		}
> -
> -		path = semanage_path(SEMANAGE_TMP, SEMANAGE_STORE_SEUSERS);
> -		if (access(path, F_OK) != 0) {
> -			do_rebuild = 1;
> -			goto rebuild;
> -		}
> -
> -		path = semanage_path(SEMANAGE_TMP, SEMANAGE_LINKED);
> -		if (access(path, F_OK) != 0) {
> -			do_rebuild = 1;
> -			goto rebuild;
> -		}
> -
> -		path = semanage_path(SEMANAGE_TMP, SEMANAGE_SEUSERS_LINKED);
> -		if (access(path, F_OK) != 0) {
> -			do_rebuild = 1;
> -			goto rebuild;
> -		}
> +		int files[] = {SEMANAGE_STORE_KERNEL,
> +					   SEMANAGE_STORE_FC,
> +					   SEMANAGE_STORE_SEUSERS,
> +					   SEMANAGE_LINKED,
> +					   SEMANAGE_SEUSERS_LINKED,
> +					   SEMANAGE_USERS_EXTRA_LINKED};
> +
> +		for (i = 0; i < (int) sizeof(files); i++) {
> +			path = semanage_path(SEMANAGE_TMP, files[i]);
> +			if (stat(path, &sb) != 0) {
> +				if (errno != ENOENT) {
> +					ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
> +					goto cleanup;

Ditto

> +				}
>  
> -		path = semanage_path(SEMANAGE_TMP, SEMANAGE_USERS_EXTRA_LINKED);
> -		if (access(path, F_OK) != 0) {
> -			do_rebuild = 1;
> -			goto rebuild;
> +				do_rebuild = 1;
> +				goto rebuild;
> +			}
>  		}
>  	}
>  
> @@ -1465,7 +1473,7 @@ rebuild:
>  			goto cleanup;
>  
>  		path = semanage_path(SEMANAGE_TMP, SEMANAGE_SEUSERS_LINKED);
> -		if (access(path, F_OK) == 0) {
> +		if (stat(path, &sb) == 0) {
>  			retval = semanage_copy_file(path,
>  						    semanage_path(SEMANAGE_TMP,
>  								  SEMANAGE_STORE_SEUSERS),
> @@ -1473,12 +1481,18 @@ rebuild:
>  			if (retval < 0)
>  				goto cleanup;
>  			pseusers->dtable->drop_cache(pseusers->dbase);
> -		} else {
> +		} else if (errno == ENOENT) {
> +			/* The file does not exist */
>  			pseusers->dtable->clear(sh, pseusers->dbase);
> +		} else {
> +			ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
> +			goto cleanup;

Ditto

>  		}
>  
> +
> +
>  		path = semanage_path(SEMANAGE_TMP, SEMANAGE_USERS_EXTRA_LINKED);
> -		if (access(path, F_OK) == 0) {
> +		if (stat(path, &sb) == 0) {
>  			retval = semanage_copy_file(path,
>  						    semanage_path(SEMANAGE_TMP,
>  								  SEMANAGE_USERS_EXTRA),
> @@ -1486,8 +1500,12 @@ rebuild:
>  			if (retval < 0)
>  				goto cleanup;
>  			pusers_extra->dtable->drop_cache(pusers_extra->dbase);
> -		} else {
> +		} else if (errno == ENOENT) {
> +			/* The file does not exist */
>  			pusers_extra->dtable->clear(sh, pusers_extra->dbase);
> +		} else {
> +			ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
> +			goto cleanup;

Ditto

>  		}
>  	}
>  
> @@ -1817,6 +1835,7 @@ static int semanage_direct_extract(semanage_handle_t * sh,
>  	ssize_t _data_len;
>  	char *_data;
>  	int compressed;
> +	struct stat sb;
>  
>  	/* get path of module */
>  	rc = semanage_module_get_path(
> @@ -1829,8 +1848,8 @@ static int semanage_direct_extract(semanage_handle_t * sh,
>  		goto cleanup;
>  	}
>  
> -	if (access(module_path, F_OK) != 0) {
> -		ERR(sh, "Module does not exist: %s", module_path);
> +	if (stat(module_path, &sb) != 0) {
> +		ERR(sh, "Unable to access %s: %s\n", module_path, strerror(errno));
>  		rc = -1;
>  		goto cleanup;
>  	}
> @@ -1859,7 +1878,12 @@ static int semanage_direct_extract(semanage_handle_t * sh,
>  		goto cleanup;
>  	}
>  
> -	if (extract_cil == 1 && strcmp(_modinfo->lang_ext, "cil") && access(input_file, F_OK) != 0) {
> +	if (extract_cil == 1 && strcmp(_modinfo->lang_ext, "cil") && stat(input_file, &sb) != 0) {
> +		if (errno != ENOENT) {
> +			ERR(sh, "Unable to access %s: %s\n", input_file, strerror(errno));

Ditto

> +			goto cleanup;
> +	
> +
>  		rc = semanage_compile_module(sh, _modinfo);
>  		if (rc < 0) {
>  			goto cleanup;
> @@ -2004,6 +2028,12 @@ static int semanage_direct_get_enabled(semanage_handle_t *sh,
>  	}
>  
>  	if (stat(path, &sb) < 0) {
> +		if (errno != ENOENT) {
> +			ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
> +			status = -1;
> +			goto cleanup;
> +		}
> +
>  		*enabled = 1;
>  	}
>  	else {
> @@ -2330,6 +2360,12 @@ static int semanage_direct_get_module_info(semanage_handle_t *sh,
>  
>  	/* set enabled/disabled status */
>  	if (stat(fn, &sb) < 0) {
> +		if (errno != ENOENT) {
> +			ERR(sh, "Unable to access %s: %s\n", fn, strerror(errno));
> +			status = -1;
> +			goto cleanup;
> +		}
> +
>  		ret = semanage_module_info_set_enabled(sh, *modinfo, 1);
>  		if (ret != 0) {
>  			status = -1;
> @@ -2738,6 +2774,7 @@ static int semanage_direct_install_info(semanage_handle_t *sh,
>  	int status = 0;
>  	int ret = 0;
>  	int type;
> +	struct stat sb;
>  
>  	char path[PATH_MAX];
>  	mode_t mask = umask(0077);
> @@ -2838,7 +2875,7 @@ static int semanage_direct_install_info(semanage_handle_t *sh,
>  			goto cleanup;
>  		}
>  
> -		if (access(path, F_OK) == 0) {
> +		if (stat(path, &sb) == 0) {
>  			ret = unlink(path);
>  			if (ret != 0) {
>  				ERR(sh, "Error while removing cached CIL file %s: %s", path, strerror(errno));
> diff --git a/libsemanage/src/semanage_store.c b/libsemanage/src/semanage_store.c
> index 4bd1d651..10f8b306 100644
> --- a/libsemanage/src/semanage_store.c
> +++ b/libsemanage/src/semanage_store.c
> @@ -514,6 +514,7 @@ char *semanage_conf_path(void)
>  {
>  	char *semanage_conf = NULL;
>  	int len;
> +	struct stat sb;
>  
>  	len = strlen(semanage_root()) + strlen(selinux_path()) + strlen(SEMANAGE_CONF_FILE);
>  	semanage_conf = calloc(len + 1, sizeof(char));
> @@ -522,7 +523,12 @@ char *semanage_conf_path(void)
>  	snprintf(semanage_conf, len + 1, "%s%s%s", semanage_root(), selinux_path(),
>  		 SEMANAGE_CONF_FILE);
>  
> -	if (access(semanage_conf, R_OK) != 0) {
> +	if (stat(semanage_conf, &sb) != 0) {
> +		if (errno != ENOENT) {
> +			/* semanage_conf exists but can't be accessed */
> +			return NULL;

Not sure this is what we want. I think we'd just return semanage_conf here, and then let the caller fail when it tries to access it, so that we get a useful error message with the pathname.

> +		}
> +
>  		snprintf(semanage_conf, len + 1, "%s%s", selinux_path(), SEMANAGE_CONF_FILE);
>  	}
>  
> @@ -1508,8 +1514,14 @@ int semanage_split_fc(semanage_handle_t * sh)
>  static int sefcontext_compile(semanage_handle_t * sh, const char *path) {
>  
>  	int r;
> +	struct stat sb;
> +
> +	if (stat(path, &sb) < 0) {
> +		if (errno != ENOENT) {
> +			ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
> +			return -1;
> +		}
>  
> -	if (access(path, F_OK) != 0) {
>  		return 0;
>  	}
>  
> 

Re: [PATCH 3/3] libsemanage: replace access() checks to make setuid programs work

[Stephen Smalley]

On 03/07/2018 09:59 AM, Stephen Smalley wrote:
> On 03/06/2018 06:58 AM, Vit Mojzis wrote:
>> access() uses real UID instead of effective UID which causes false
>> negative checks in setuid programs.
>> Replace access(,F_OK) (i.e. tests for file existence) by stat().
>> And access(,R_OK) by fopen(,"r")

Also, in addition to fixing the code, please update the patch description since the last line is no longer accurate.

>>
>> Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1186431
>>
>> Signed-off-by: Vit Mojzis <vmojzis@redhat.com>
>> ---
>>  libsemanage/src/direct_api.c     | 133 +++++++++++++++++++++++++--------------
>>  libsemanage/src/semanage_store.c |  16 ++++-
>>  2 files changed, 99 insertions(+), 50 deletions(-)
>>
>> diff --git a/libsemanage/src/direct_api.c b/libsemanage/src/direct_api.c
>> index 49cac14f..4e2af810 100644
>> --- a/libsemanage/src/direct_api.c
>> +++ b/libsemanage/src/direct_api.c
>> @@ -140,6 +140,7 @@ int semanage_direct_is_managed(semanage_handle_t * sh)
>>  int semanage_direct_connect(semanage_handle_t * sh)
>>  {
>>  	const char *path;
>> +	struct stat sb;
>>  
>>  	if (semanage_check_init(sh, sh->conf->store_root_path))
>>  		goto err;
>> @@ -302,10 +303,16 @@ int semanage_direct_connect(semanage_handle_t * sh)
>>  
>>  	/* set the disable dontaudit value */
>>  	path = semanage_path(SEMANAGE_ACTIVE, SEMANAGE_DISABLE_DONTAUDIT);
>> -	if (access(path, F_OK) == 0)
>> +
>> +	if (stat(path, &sb) == 0)
>>  		sepol_set_disable_dontaudit(sh->sepolh, 1);
>> -	else
>> +	else if (errno == ENOENT) {
>> +		/* The file does not exist */
>>  		sepol_set_disable_dontaudit(sh->sepolh, 0);
>> +	} else {
>> +		ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
>> +		goto err;
>> +	}
>>  
>>  	return STATUS_SUCCESS;
>>  
>> @@ -1139,6 +1146,7 @@ static int semanage_compile_hll_modules(semanage_handle_t *sh,
>>  	int status = 0;
>>  	int i;
>>  	char cil_path[PATH_MAX];
>> +	struct stat sb;
>>  
>>  	assert(sh);
>>  	assert(modinfos);
>> @@ -1155,9 +1163,13 @@ static int semanage_compile_hll_modules(semanage_handle_t *sh,
>>  		}
>>  
>>  		if (semanage_get_ignore_module_cache(sh) == 0 &&
>> -				access(cil_path, F_OK) == 0) {
>> +				(status = stat(cil_path, &sb)) == 0) {
>>  			continue;
>>  		}
>> +		if (status != 0 && errno != ENOENT) {
>> +			ERR(sh, "Unable to access %s: %s\n", cil_path, strerror(errno));
>> +			goto cleanup; //an error in the "stat" call
>> +		}
>>  
>>  		status = semanage_compile_module(sh, &modinfos[i]);
>>  		if (status < 0) {
>> @@ -1196,6 +1208,7 @@ static int semanage_direct_commit(semanage_handle_t * sh)
>>  	struct cil_db *cildb = NULL;
>>  	semanage_module_info_t *modinfos = NULL;
>>  	mode_t mask = umask(0077);
>> +	struct stat sb;
>>  
>>  	int do_rebuild, do_write_kernel, do_install;
>>  	int fcontexts_modified, ports_modified, seusers_modified,
>> @@ -1234,10 +1247,15 @@ static int semanage_direct_commit(semanage_handle_t * sh)
>>  
>>  	/* Create or remove the disable_dontaudit flag file. */
>>  	path = semanage_path(SEMANAGE_TMP, SEMANAGE_DISABLE_DONTAUDIT);
>> -	if (access(path, F_OK) == 0)
>> +	if (stat(path, &sb) == 0)
>>  		do_rebuild |= !(sepol_get_disable_dontaudit(sh->sepolh) == 1);
>> -	else
>> +	else if (errno == ENOENT) {
>> +		/* The file does not exist */
>>  		do_rebuild |= (sepol_get_disable_dontaudit(sh->sepolh) == 1);
>> +	} else {
>> +		ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
> 
> We need to ensure that retval is set in all of these cases.  Safest to always set it before goto cleanup,
> either explicitly to -1 or to return value of stat() call above.
> 
>> +		goto cleanup;
>> +	}
>>  	if (sepol_get_disable_dontaudit(sh->sepolh) == 1) {
>>  		FILE *touch;
>>  		touch = fopen(path, "w");
>> @@ -1259,10 +1277,16 @@ static int semanage_direct_commit(semanage_handle_t * sh)
>>  
>>  	/* Create or remove the preserve_tunables flag file. */
>>  	path = semanage_path(SEMANAGE_TMP, SEMANAGE_PRESERVE_TUNABLES);
>> -	if (access(path, F_OK) == 0)
>> +	if (stat(path, &sb) == 0)
>>  		do_rebuild |= !(sepol_get_preserve_tunables(sh->sepolh) == 1);
>> -	else
>> +	else if (errno == ENOENT) {
>> +		/* The file does not exist */
>>  		do_rebuild |= (sepol_get_preserve_tunables(sh->sepolh) == 1);
>> +	} else {
>> +		ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
>> +		goto cleanup;
>> +	}
> 
> Ditto
> 
>> +
>>  	if (sepol_get_preserve_tunables(sh->sepolh) == 1) {
>>  		FILE *touch;
>>  		touch = fopen(path, "w");
>> @@ -1299,40 +1323,24 @@ static int semanage_direct_commit(semanage_handle_t * sh)
>>  	 * a rebuild.
>>  	 */
>>  	if (!do_rebuild) {
>> -		path = semanage_path(SEMANAGE_TMP, SEMANAGE_STORE_KERNEL);
>> -		if (access(path, F_OK) != 0) {
>> -			do_rebuild = 1;
>> -			goto rebuild;
>> -		}
>> -
>> -		path = semanage_path(SEMANAGE_TMP, SEMANAGE_STORE_FC);
>> -		if (access(path, F_OK) != 0) {
>> -			do_rebuild = 1;
>> -			goto rebuild;
>> -		}
>> -
>> -		path = semanage_path(SEMANAGE_TMP, SEMANAGE_STORE_SEUSERS);
>> -		if (access(path, F_OK) != 0) {
>> -			do_rebuild = 1;
>> -			goto rebuild;
>> -		}
>> -
>> -		path = semanage_path(SEMANAGE_TMP, SEMANAGE_LINKED);
>> -		if (access(path, F_OK) != 0) {
>> -			do_rebuild = 1;
>> -			goto rebuild;
>> -		}
>> -
>> -		path = semanage_path(SEMANAGE_TMP, SEMANAGE_SEUSERS_LINKED);
>> -		if (access(path, F_OK) != 0) {
>> -			do_rebuild = 1;
>> -			goto rebuild;
>> -		}
>> +		int files[] = {SEMANAGE_STORE_KERNEL,
>> +					   SEMANAGE_STORE_FC,
>> +					   SEMANAGE_STORE_SEUSERS,
>> +					   SEMANAGE_LINKED,
>> +					   SEMANAGE_SEUSERS_LINKED,
>> +					   SEMANAGE_USERS_EXTRA_LINKED};
>> +
>> +		for (i = 0; i < (int) sizeof(files); i++) {
>> +			path = semanage_path(SEMANAGE_TMP, files[i]);
>> +			if (stat(path, &sb) != 0) {
>> +				if (errno != ENOENT) {
>> +					ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
>> +					goto cleanup;
> 
> Ditto
> 
>> +				}
>>  
>> -		path = semanage_path(SEMANAGE_TMP, SEMANAGE_USERS_EXTRA_LINKED);
>> -		if (access(path, F_OK) != 0) {
>> -			do_rebuild = 1;
>> -			goto rebuild;
>> +				do_rebuild = 1;
>> +				goto rebuild;
>> +			}
>>  		}
>>  	}
>>  
>> @@ -1465,7 +1473,7 @@ rebuild:
>>  			goto cleanup;
>>  
>>  		path = semanage_path(SEMANAGE_TMP, SEMANAGE_SEUSERS_LINKED);
>> -		if (access(path, F_OK) == 0) {
>> +		if (stat(path, &sb) == 0) {
>>  			retval = semanage_copy_file(path,
>>  						    semanage_path(SEMANAGE_TMP,
>>  								  SEMANAGE_STORE_SEUSERS),
>> @@ -1473,12 +1481,18 @@ rebuild:
>>  			if (retval < 0)
>>  				goto cleanup;
>>  			pseusers->dtable->drop_cache(pseusers->dbase);
>> -		} else {
>> +		} else if (errno == ENOENT) {
>> +			/* The file does not exist */
>>  			pseusers->dtable->clear(sh, pseusers->dbase);
>> +		} else {
>> +			ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
>> +			goto cleanup;
> 
> Ditto
> 
>>  		}
>>  
>> +
>> +
>>  		path = semanage_path(SEMANAGE_TMP, SEMANAGE_USERS_EXTRA_LINKED);
>> -		if (access(path, F_OK) == 0) {
>> +		if (stat(path, &sb) == 0) {
>>  			retval = semanage_copy_file(path,
>>  						    semanage_path(SEMANAGE_TMP,
>>  								  SEMANAGE_USERS_EXTRA),
>> @@ -1486,8 +1500,12 @@ rebuild:
>>  			if (retval < 0)
>>  				goto cleanup;
>>  			pusers_extra->dtable->drop_cache(pusers_extra->dbase);
>> -		} else {
>> +		} else if (errno == ENOENT) {
>> +			/* The file does not exist */
>>  			pusers_extra->dtable->clear(sh, pusers_extra->dbase);
>> +		} else {
>> +			ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
>> +			goto cleanup;
> 
> Ditto
> 
>>  		}
>>  	}
>>  
>> @@ -1817,6 +1835,7 @@ static int semanage_direct_extract(semanage_handle_t * sh,
>>  	ssize_t _data_len;
>>  	char *_data;
>>  	int compressed;
>> +	struct stat sb;
>>  
>>  	/* get path of module */
>>  	rc = semanage_module_get_path(
>> @@ -1829,8 +1848,8 @@ static int semanage_direct_extract(semanage_handle_t * sh,
>>  		goto cleanup;
>>  	}
>>  
>> -	if (access(module_path, F_OK) != 0) {
>> -		ERR(sh, "Module does not exist: %s", module_path);
>> +	if (stat(module_path, &sb) != 0) {
>> +		ERR(sh, "Unable to access %s: %s\n", module_path, strerror(errno));
>>  		rc = -1;
>>  		goto cleanup;
>>  	}
>> @@ -1859,7 +1878,12 @@ static int semanage_direct_extract(semanage_handle_t * sh,
>>  		goto cleanup;
>>  	}
>>  
>> -	if (extract_cil == 1 && strcmp(_modinfo->lang_ext, "cil") && access(input_file, F_OK) != 0) {
>> +	if (extract_cil == 1 && strcmp(_modinfo->lang_ext, "cil") && stat(input_file, &sb) != 0) {
>> +		if (errno != ENOENT) {
>> +			ERR(sh, "Unable to access %s: %s\n", input_file, strerror(errno));
> 
> Ditto
> 
>> +			goto cleanup;
>> +	
>> +
>>  		rc = semanage_compile_module(sh, _modinfo);
>>  		if (rc < 0) {
>>  			goto cleanup;
>> @@ -2004,6 +2028,12 @@ static int semanage_direct_get_enabled(semanage_handle_t *sh,
>>  	}
>>  
>>  	if (stat(path, &sb) < 0) {
>> +		if (errno != ENOENT) {
>> +			ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
>> +			status = -1;
>> +			goto cleanup;
>> +		}
>> +
>>  		*enabled = 1;
>>  	}
>>  	else {
>> @@ -2330,6 +2360,12 @@ static int semanage_direct_get_module_info(semanage_handle_t *sh,
>>  
>>  	/* set enabled/disabled status */
>>  	if (stat(fn, &sb) < 0) {
>> +		if (errno != ENOENT) {
>> +			ERR(sh, "Unable to access %s: %s\n", fn, strerror(errno));
>> +			status = -1;
>> +			goto cleanup;
>> +		}
>> +
>>  		ret = semanage_module_info_set_enabled(sh, *modinfo, 1);
>>  		if (ret != 0) {
>>  			status = -1;
>> @@ -2738,6 +2774,7 @@ static int semanage_direct_install_info(semanage_handle_t *sh,
>>  	int status = 0;
>>  	int ret = 0;
>>  	int type;
>> +	struct stat sb;
>>  
>>  	char path[PATH_MAX];
>>  	mode_t mask = umask(0077);
>> @@ -2838,7 +2875,7 @@ static int semanage_direct_install_info(semanage_handle_t *sh,
>>  			goto cleanup;
>>  		}
>>  
>> -		if (access(path, F_OK) == 0) {
>> +		if (stat(path, &sb) == 0) {
>>  			ret = unlink(path);
>>  			if (ret != 0) {
>>  				ERR(sh, "Error while removing cached CIL file %s: %s", path, strerror(errno));
>> diff --git a/libsemanage/src/semanage_store.c b/libsemanage/src/semanage_store.c
>> index 4bd1d651..10f8b306 100644
>> --- a/libsemanage/src/semanage_store.c
>> +++ b/libsemanage/src/semanage_store.c
>> @@ -514,6 +514,7 @@ char *semanage_conf_path(void)
>>  {
>>  	char *semanage_conf = NULL;
>>  	int len;
>> +	struct stat sb;
>>  
>>  	len = strlen(semanage_root()) + strlen(selinux_path()) + strlen(SEMANAGE_CONF_FILE);
>>  	semanage_conf = calloc(len + 1, sizeof(char));
>> @@ -522,7 +523,12 @@ char *semanage_conf_path(void)
>>  	snprintf(semanage_conf, len + 1, "%s%s%s", semanage_root(), selinux_path(),
>>  		 SEMANAGE_CONF_FILE);
>>  
>> -	if (access(semanage_conf, R_OK) != 0) {
>> +	if (stat(semanage_conf, &sb) != 0) {
>> +		if (errno != ENOENT) {
>> +			/* semanage_conf exists but can't be accessed */
>> +			return NULL;
> 
> Not sure this is what we want. I think we'd just return semanage_conf here, and then let the caller fail when it tries to access it, so that we get a useful error message with the pathname.
> 
>> +		}
>> +
>>  		snprintf(semanage_conf, len + 1, "%s%s", selinux_path(), SEMANAGE_CONF_FILE);
>>  	}
>>  
>> @@ -1508,8 +1514,14 @@ int semanage_split_fc(semanage_handle_t * sh)
>>  static int sefcontext_compile(semanage_handle_t * sh, const char *path) {
>>  
>>  	int r;
>> +	struct stat sb;
>> +
>> +	if (stat(path, &sb) < 0) {
>> +		if (errno != ENOENT) {
>> +			ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
>> +			return -1;
>> +		}
>>  
>> -	if (access(path, F_OK) != 0) {
>>  		return 0;
>>  	}
>>  
>>
> 
> 

Re: [PATCH 3/3] libsemanage: replace access() checks to make setuid programs work

[Vit Mojzis]

On 7.3.2018 15:59, Stephen Smalley wrote:
> On 03/06/2018 06:58 AM, Vit Mojzis wrote:
>> access() uses real UID instead of effective UID which causes false
>> negative checks in setuid programs.
>> Replace access(,F_OK) (i.e. tests for file existence) by stat().
>> And access(,R_OK) by fopen(,"r")
>>
>> Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1186431
>>
>> Signed-off-by: Vit Mojzis <vmojzis@redhat.com>
>> ---
>>   libsemanage/src/direct_api.c     | 133 +++++++++++++++++++++++++--------------
>>   libsemanage/src/semanage_store.c |  16 ++++-
>>   2 files changed, 99 insertions(+), 50 deletions(-)
>>
>> diff --git a/libsemanage/src/direct_api.c b/libsemanage/src/direct_api.c
>> index 49cac14f..4e2af810 100644
>> --- a/libsemanage/src/direct_api.c
>> +++ b/libsemanage/src/direct_api.c
>> @@ -140,6 +140,7 @@ int semanage_direct_is_managed(semanage_handle_t * sh)
>>   int semanage_direct_connect(semanage_handle_t * sh)
>>   {
>>   	const char *path;
>> +	struct stat sb;
>>   
>>   	if (semanage_check_init(sh, sh->conf->store_root_path))
>>   		goto err;
>> @@ -302,10 +303,16 @@ int semanage_direct_connect(semanage_handle_t * sh)
>>   
>>   	/* set the disable dontaudit value */
>>   	path = semanage_path(SEMANAGE_ACTIVE, SEMANAGE_DISABLE_DONTAUDIT);
>> -	if (access(path, F_OK) == 0)
>> +
>> +	if (stat(path, &sb) == 0)
>>   		sepol_set_disable_dontaudit(sh->sepolh, 1);
>> -	else
>> +	else if (errno == ENOENT) {
>> +		/* The file does not exist */
>>   		sepol_set_disable_dontaudit(sh->sepolh, 0);
>> +	} else {
>> +		ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
>> +		goto err;
>> +	}
>>   
>>   	return STATUS_SUCCESS;
>>   
>> @@ -1139,6 +1146,7 @@ static int semanage_compile_hll_modules(semanage_handle_t *sh,
>>   	int status = 0;
>>   	int i;
>>   	char cil_path[PATH_MAX];
>> +	struct stat sb;
>>   
>>   	assert(sh);
>>   	assert(modinfos);
>> @@ -1155,9 +1163,13 @@ static int semanage_compile_hll_modules(semanage_handle_t *sh,
>>   		}
>>   
>>   		if (semanage_get_ignore_module_cache(sh) == 0 &&
>> -				access(cil_path, F_OK) == 0) {
>> +				(status = stat(cil_path, &sb)) == 0) {
>>   			continue;
>>   		}
>> +		if (status != 0 && errno != ENOENT) {
>> +			ERR(sh, "Unable to access %s: %s\n", cil_path, strerror(errno));
>> +			goto cleanup; //an error in the "stat" call
>> +		}
>>   
>>   		status = semanage_compile_module(sh, &modinfos[i]);
>>   		if (status < 0) {
>> @@ -1196,6 +1208,7 @@ static int semanage_direct_commit(semanage_handle_t * sh)
>>   	struct cil_db *cildb = NULL;
>>   	semanage_module_info_t *modinfos = NULL;
>>   	mode_t mask = umask(0077);
>> +	struct stat sb;
>>   
>>   	int do_rebuild, do_write_kernel, do_install;
>>   	int fcontexts_modified, ports_modified, seusers_modified,
>> @@ -1234,10 +1247,15 @@ static int semanage_direct_commit(semanage_handle_t * sh)
>>   
>>   	/* Create or remove the disable_dontaudit flag file. */
>>   	path = semanage_path(SEMANAGE_TMP, SEMANAGE_DISABLE_DONTAUDIT);
>> -	if (access(path, F_OK) == 0)
>> +	if (stat(path, &sb) == 0)
>>   		do_rebuild |= !(sepol_get_disable_dontaudit(sh->sepolh) == 1);
>> -	else
>> +	else if (errno == ENOENT) {
>> +		/* The file does not exist */
>>   		do_rebuild |= (sepol_get_disable_dontaudit(sh->sepolh) == 1);
>> +	} else {
>> +		ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
> We need to ensure that retval is set in all of these cases.  Safest to always set it before goto cleanup,
> either explicitly to -1 or to return value of stat() call above.
Thank you.
The retval is actually initialized to -1 (and stat() returns -1 for any 
error) so it's not necessary to set it here. It will be necessary a 
little bit down the road after the first assignment to retval, you're right.
Should I set it to -1 here anyway to make it less prone to breaking due 
to future changes in the code (what about the other ERR calls in this 
section of the code)?

>> +		goto cleanup;
>> +	}
>>   	if (sepol_get_disable_dontaudit(sh->sepolh) == 1) {
>>   		FILE *touch;
>>   		touch = fopen(path, "w");
>> @@ -1259,10 +1277,16 @@ static int semanage_direct_commit(semanage_handle_t * sh)
>>   
>>   	/* Create or remove the preserve_tunables flag file. */
>>   	path = semanage_path(SEMANAGE_TMP, SEMANAGE_PRESERVE_TUNABLES);
>> -	if (access(path, F_OK) == 0)
>> +	if (stat(path, &sb) == 0)
>>   		do_rebuild |= !(sepol_get_preserve_tunables(sh->sepolh) == 1);
>> -	else
>> +	else if (errno == ENOENT) {
>> +		/* The file does not exist */
>>   		do_rebuild |= (sepol_get_preserve_tunables(sh->sepolh) == 1);
>> +	} else {
>> +		ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
>> +		goto cleanup;
>> +	}
> Ditto
>
>> +
>>   	if (sepol_get_preserve_tunables(sh->sepolh) == 1) {
>>   		FILE *touch;
>>   		touch = fopen(path, "w");
>> @@ -1299,40 +1323,24 @@ static int semanage_direct_commit(semanage_handle_t * sh)
>>   	 * a rebuild.
>>   	 */
>>   	if (!do_rebuild) {
>> -		path = semanage_path(SEMANAGE_TMP, SEMANAGE_STORE_KERNEL);
>> -		if (access(path, F_OK) != 0) {
>> -			do_rebuild = 1;
>> -			goto rebuild;
>> -		}
>> -
>> -		path = semanage_path(SEMANAGE_TMP, SEMANAGE_STORE_FC);
>> -		if (access(path, F_OK) != 0) {
>> -			do_rebuild = 1;
>> -			goto rebuild;
>> -		}
>> -
>> -		path = semanage_path(SEMANAGE_TMP, SEMANAGE_STORE_SEUSERS);
>> -		if (access(path, F_OK) != 0) {
>> -			do_rebuild = 1;
>> -			goto rebuild;
>> -		}
>> -
>> -		path = semanage_path(SEMANAGE_TMP, SEMANAGE_LINKED);
>> -		if (access(path, F_OK) != 0) {
>> -			do_rebuild = 1;
>> -			goto rebuild;
>> -		}
>> -
>> -		path = semanage_path(SEMANAGE_TMP, SEMANAGE_SEUSERS_LINKED);
>> -		if (access(path, F_OK) != 0) {
>> -			do_rebuild = 1;
>> -			goto rebuild;
>> -		}
>> +		int files[] = {SEMANAGE_STORE_KERNEL,
>> +					   SEMANAGE_STORE_FC,
>> +					   SEMANAGE_STORE_SEUSERS,
>> +					   SEMANAGE_LINKED,
>> +					   SEMANAGE_SEUSERS_LINKED,
>> +					   SEMANAGE_USERS_EXTRA_LINKED};
>> +
>> +		for (i = 0; i < (int) sizeof(files); i++) {
>> +			path = semanage_path(SEMANAGE_TMP, files[i]);
>> +			if (stat(path, &sb) != 0) {
>> +				if (errno != ENOENT) {
>> +					ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
>> +					goto cleanup;
> Ditto
>
>> +				}
>>   
>> -		path = semanage_path(SEMANAGE_TMP, SEMANAGE_USERS_EXTRA_LINKED);
>> -		if (access(path, F_OK) != 0) {
>> -			do_rebuild = 1;
>> -			goto rebuild;
>> +				do_rebuild = 1;
>> +				goto rebuild;
>> +			}
>>   		}
>>   	}
>>   
>> @@ -1465,7 +1473,7 @@ rebuild:
>>   			goto cleanup;
>>   
>>   		path = semanage_path(SEMANAGE_TMP, SEMANAGE_SEUSERS_LINKED);
>> -		if (access(path, F_OK) == 0) {
>> +		if (stat(path, &sb) == 0) {
>>   			retval = semanage_copy_file(path,
>>   						    semanage_path(SEMANAGE_TMP,
>>   								  SEMANAGE_STORE_SEUSERS),
>> @@ -1473,12 +1481,18 @@ rebuild:
>>   			if (retval < 0)
>>   				goto cleanup;
>>   			pseusers->dtable->drop_cache(pseusers->dbase);
>> -		} else {
>> +		} else if (errno == ENOENT) {
>> +			/* The file does not exist */
>>   			pseusers->dtable->clear(sh, pseusers->dbase);
>> +		} else {
>> +			ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
>> +			goto cleanup;
> Ditto
>
>>   		}
>>   
>> +
>> +
>>   		path = semanage_path(SEMANAGE_TMP, SEMANAGE_USERS_EXTRA_LINKED);
>> -		if (access(path, F_OK) == 0) {
>> +		if (stat(path, &sb) == 0) {
>>   			retval = semanage_copy_file(path,
>>   						    semanage_path(SEMANAGE_TMP,
>>   								  SEMANAGE_USERS_EXTRA),
>> @@ -1486,8 +1500,12 @@ rebuild:
>>   			if (retval < 0)
>>   				goto cleanup;
>>   			pusers_extra->dtable->drop_cache(pusers_extra->dbase);
>> -		} else {
>> +		} else if (errno == ENOENT) {
>> +			/* The file does not exist */
>>   			pusers_extra->dtable->clear(sh, pusers_extra->dbase);
>> +		} else {
>> +			ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
>> +			goto cleanup;
> Ditto
>
>>   		}
>>   	}
>>   
>> @@ -1817,6 +1835,7 @@ static int semanage_direct_extract(semanage_handle_t * sh,
>>   	ssize_t _data_len;
>>   	char *_data;
>>   	int compressed;
>> +	struct stat sb;
>>   
>>   	/* get path of module */
>>   	rc = semanage_module_get_path(
>> @@ -1829,8 +1848,8 @@ static int semanage_direct_extract(semanage_handle_t * sh,
>>   		goto cleanup;
>>   	}
>>   
>> -	if (access(module_path, F_OK) != 0) {
>> -		ERR(sh, "Module does not exist: %s", module_path);
>> +	if (stat(module_path, &sb) != 0) {
>> +		ERR(sh, "Unable to access %s: %s\n", module_path, strerror(errno));
>>   		rc = -1;
>>   		goto cleanup;
>>   	}
>> @@ -1859,7 +1878,12 @@ static int semanage_direct_extract(semanage_handle_t * sh,
>>   		goto cleanup;
>>   	}
>>   
>> -	if (extract_cil == 1 && strcmp(_modinfo->lang_ext, "cil") && access(input_file, F_OK) != 0) {
>> +	if (extract_cil == 1 && strcmp(_modinfo->lang_ext, "cil") && stat(input_file, &sb) != 0) {
>> +		if (errno != ENOENT) {
>> +			ERR(sh, "Unable to access %s: %s\n", input_file, strerror(errno));
> Ditto
>
>> +			goto cleanup;
>> +	
>> +
>>   		rc = semanage_compile_module(sh, _modinfo);
>>   		if (rc < 0) {
>>   			goto cleanup;
>> @@ -2004,6 +2028,12 @@ static int semanage_direct_get_enabled(semanage_handle_t *sh,
>>   	}
>>   
>>   	if (stat(path, &sb) < 0) {
>> +		if (errno != ENOENT) {
>> +			ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
>> +			status = -1;
>> +			goto cleanup;
>> +		}
>> +
>>   		*enabled = 1;
>>   	}
>>   	else {
>> @@ -2330,6 +2360,12 @@ static int semanage_direct_get_module_info(semanage_handle_t *sh,
>>   
>>   	/* set enabled/disabled status */
>>   	if (stat(fn, &sb) < 0) {
>> +		if (errno != ENOENT) {
>> +			ERR(sh, "Unable to access %s: %s\n", fn, strerror(errno));
>> +			status = -1;
>> +			goto cleanup;
>> +		}
>> +
>>   		ret = semanage_module_info_set_enabled(sh, *modinfo, 1);
>>   		if (ret != 0) {
>>   			status = -1;
>> @@ -2738,6 +2774,7 @@ static int semanage_direct_install_info(semanage_handle_t *sh,
>>   	int status = 0;
>>   	int ret = 0;
>>   	int type;
>> +	struct stat sb;
>>   
>>   	char path[PATH_MAX];
>>   	mode_t mask = umask(0077);
>> @@ -2838,7 +2875,7 @@ static int semanage_direct_install_info(semanage_handle_t *sh,
>>   			goto cleanup;
>>   		}
>>   
>> -		if (access(path, F_OK) == 0) {
>> +		if (stat(path, &sb) == 0) {
>>   			ret = unlink(path);
>>   			if (ret != 0) {
>>   				ERR(sh, "Error while removing cached CIL file %s: %s", path, strerror(errno));
>> diff --git a/libsemanage/src/semanage_store.c b/libsemanage/src/semanage_store.c
>> index 4bd1d651..10f8b306 100644
>> --- a/libsemanage/src/semanage_store.c
>> +++ b/libsemanage/src/semanage_store.c
>> @@ -514,6 +514,7 @@ char *semanage_conf_path(void)
>>   {
>>   	char *semanage_conf = NULL;
>>   	int len;
>> +	struct stat sb;
>>   
>>   	len = strlen(semanage_root()) + strlen(selinux_path()) + strlen(SEMANAGE_CONF_FILE);
>>   	semanage_conf = calloc(len + 1, sizeof(char));
>> @@ -522,7 +523,12 @@ char *semanage_conf_path(void)
>>   	snprintf(semanage_conf, len + 1, "%s%s%s", semanage_root(), selinux_path(),
>>   		 SEMANAGE_CONF_FILE);
>>   
>> -	if (access(semanage_conf, R_OK) != 0) {
>> +	if (stat(semanage_conf, &sb) != 0) {
>> +		if (errno != ENOENT) {
>> +			/* semanage_conf exists but can't be accessed */
>> +			return NULL;
> Not sure this is what we want. I think we'd just return semanage_conf here, and then let the caller fail when it tries to access it, so that we get a useful error message with the pathname.
>
>> +		}
>> +
>>   		snprintf(semanage_conf, len + 1, "%s%s", selinux_path(), SEMANAGE_CONF_FILE);
>>   	}
>>   
>> @@ -1508,8 +1514,14 @@ int semanage_split_fc(semanage_handle_t * sh)
>>   static int sefcontext_compile(semanage_handle_t * sh, const char *path) {
>>   
>>   	int r;
>> +	struct stat sb;
>> +
>> +	if (stat(path, &sb) < 0) {
>> +		if (errno != ENOENT) {
>> +			ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
>> +			return -1;
>> +		}
>>   
>> -	if (access(path, F_OK) != 0) {
>>   		return 0;
>>   	}
>>   
>>

Re: [PATCH 3/3] libsemanage: replace access() checks to make setuid programs work

[Stephen Smalley]

On 03/09/2018 08:14 AM, Vit Mojzis wrote:
> 
> 
> On 7.3.2018 15:59, Stephen Smalley wrote:
>> On 03/06/2018 06:58 AM, Vit Mojzis wrote:
>>> access() uses real UID instead of effective UID which causes false
>>> negative checks in setuid programs.
>>> Replace access(,F_OK) (i.e. tests for file existence) by stat().
>>> And access(,R_OK) by fopen(,"r")
>>>
>>> Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1186431
>>>
>>> Signed-off-by: Vit Mojzis <vmojzis@redhat.com>
>>> ---
>>>   libsemanage/src/direct_api.c     | 133 +++++++++++++++++++++++++--------------
>>>   libsemanage/src/semanage_store.c |  16 ++++-
>>>   2 files changed, 99 insertions(+), 50 deletions(-)
>>>
>>> diff --git a/libsemanage/src/direct_api.c b/libsemanage/src/direct_api.c
>>> index 49cac14f..4e2af810 100644
>>> --- a/libsemanage/src/direct_api.c
>>> +++ b/libsemanage/src/direct_api.c
>>> @@ -140,6 +140,7 @@ int semanage_direct_is_managed(semanage_handle_t * sh)
>>>   int semanage_direct_connect(semanage_handle_t * sh)
>>>   {
>>>       const char *path;
>>> +    struct stat sb;
>>>         if (semanage_check_init(sh, sh->conf->store_root_path))
>>>           goto err;
>>> @@ -302,10 +303,16 @@ int semanage_direct_connect(semanage_handle_t * sh)
>>>         /* set the disable dontaudit value */
>>>       path = semanage_path(SEMANAGE_ACTIVE, SEMANAGE_DISABLE_DONTAUDIT);
>>> -    if (access(path, F_OK) == 0)
>>> +
>>> +    if (stat(path, &sb) == 0)
>>>           sepol_set_disable_dontaudit(sh->sepolh, 1);
>>> -    else
>>> +    else if (errno == ENOENT) {
>>> +        /* The file does not exist */
>>>           sepol_set_disable_dontaudit(sh->sepolh, 0);
>>> +    } else {
>>> +        ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
>>> +        goto err;
>>> +    }
>>>         return STATUS_SUCCESS;
>>>   @@ -1139,6 +1146,7 @@ static int semanage_compile_hll_modules(semanage_handle_t *sh,
>>>       int status = 0;
>>>       int i;
>>>       char cil_path[PATH_MAX];
>>> +    struct stat sb;
>>>         assert(sh);
>>>       assert(modinfos);
>>> @@ -1155,9 +1163,13 @@ static int semanage_compile_hll_modules(semanage_handle_t *sh,
>>>           }
>>>             if (semanage_get_ignore_module_cache(sh) == 0 &&
>>> -                access(cil_path, F_OK) == 0) {
>>> +                (status = stat(cil_path, &sb)) == 0) {
>>>               continue;
>>>           }
>>> +        if (status != 0 && errno != ENOENT) {
>>> +            ERR(sh, "Unable to access %s: %s\n", cil_path, strerror(errno));
>>> +            goto cleanup; //an error in the "stat" call
>>> +        }
>>>             status = semanage_compile_module(sh, &modinfos[i]);
>>>           if (status < 0) {
>>> @@ -1196,6 +1208,7 @@ static int semanage_direct_commit(semanage_handle_t * sh)
>>>       struct cil_db *cildb = NULL;
>>>       semanage_module_info_t *modinfos = NULL;
>>>       mode_t mask = umask(0077);
>>> +    struct stat sb;
>>>         int do_rebuild, do_write_kernel, do_install;
>>>       int fcontexts_modified, ports_modified, seusers_modified,
>>> @@ -1234,10 +1247,15 @@ static int semanage_direct_commit(semanage_handle_t * sh)
>>>         /* Create or remove the disable_dontaudit flag file. */
>>>       path = semanage_path(SEMANAGE_TMP, SEMANAGE_DISABLE_DONTAUDIT);
>>> -    if (access(path, F_OK) == 0)
>>> +    if (stat(path, &sb) == 0)
>>>           do_rebuild |= !(sepol_get_disable_dontaudit(sh->sepolh) == 1);
>>> -    else
>>> +    else if (errno == ENOENT) {
>>> +        /* The file does not exist */
>>>           do_rebuild |= (sepol_get_disable_dontaudit(sh->sepolh) == 1);
>>> +    } else {
>>> +        ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
>> We need to ensure that retval is set in all of these cases.  Safest to always set it before goto cleanup,
>> either explicitly to -1 or to return value of stat() call above.
> Thank you.
> The retval is actually initialized to -1 (and stat() returns -1 for any error) so it's not necessary to set it here. It will be necessary a little bit down the road after the first assignment to retval, you're right.
> Should I set it to -1 here anyway to make it less prone to breaking due to future changes in the code (what about the other ERR calls in this section of the code)?

Yes, I would do that for safety here and in any other case where we didn't just set retval and test it.  IOW, any case where we have:
	retval = foo(args);
	if (retval < 0) {
		ERR(...)
		goto cleanup;
	}
is fine as is, but any case where we have:
	if (some-condition-other-than-retval-less-than-0) {
		ERR(...)
		goto cleanup;
	}
likely ought to explicitly set retval.

If we have too many of those, then maybe we ought to have an err: label that sets retval to -1 explicitly and goto it instead.

> 
>>> +        goto cleanup;
>>> +    }
>>>       if (sepol_get_disable_dontaudit(sh->sepolh) == 1) {
>>>           FILE *touch;
>>>           touch = fopen(path, "w");
>>> @@ -1259,10 +1277,16 @@ static int semanage_direct_commit(semanage_handle_t * sh)
>>>         /* Create or remove the preserve_tunables flag file. */
>>>       path = semanage_path(SEMANAGE_TMP, SEMANAGE_PRESERVE_TUNABLES);
>>> -    if (access(path, F_OK) == 0)
>>> +    if (stat(path, &sb) == 0)
>>>           do_rebuild |= !(sepol_get_preserve_tunables(sh->sepolh) == 1);
>>> -    else
>>> +    else if (errno == ENOENT) {
>>> +        /* The file does not exist */
>>>           do_rebuild |= (sepol_get_preserve_tunables(sh->sepolh) == 1);
>>> +    } else {
>>> +        ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
>>> +        goto cleanup;
>>> +    }
>> Ditto
>>
>>> +
>>>       if (sepol_get_preserve_tunables(sh->sepolh) == 1) {
>>>           FILE *touch;
>>>           touch = fopen(path, "w");
>>> @@ -1299,40 +1323,24 @@ static int semanage_direct_commit(semanage_handle_t * sh)
>>>        * a rebuild.
>>>        */
>>>       if (!do_rebuild) {
>>> -        path = semanage_path(SEMANAGE_TMP, SEMANAGE_STORE_KERNEL);
>>> -        if (access(path, F_OK) != 0) {
>>> -            do_rebuild = 1;
>>> -            goto rebuild;
>>> -        }
>>> -
>>> -        path = semanage_path(SEMANAGE_TMP, SEMANAGE_STORE_FC);
>>> -        if (access(path, F_OK) != 0) {
>>> -            do_rebuild = 1;
>>> -            goto rebuild;
>>> -        }
>>> -
>>> -        path = semanage_path(SEMANAGE_TMP, SEMANAGE_STORE_SEUSERS);
>>> -        if (access(path, F_OK) != 0) {
>>> -            do_rebuild = 1;
>>> -            goto rebuild;
>>> -        }
>>> -
>>> -        path = semanage_path(SEMANAGE_TMP, SEMANAGE_LINKED);
>>> -        if (access(path, F_OK) != 0) {
>>> -            do_rebuild = 1;
>>> -            goto rebuild;
>>> -        }
>>> -
>>> -        path = semanage_path(SEMANAGE_TMP, SEMANAGE_SEUSERS_LINKED);
>>> -        if (access(path, F_OK) != 0) {
>>> -            do_rebuild = 1;
>>> -            goto rebuild;
>>> -        }
>>> +        int files[] = {SEMANAGE_STORE_KERNEL,
>>> +                       SEMANAGE_STORE_FC,
>>> +                       SEMANAGE_STORE_SEUSERS,
>>> +                       SEMANAGE_LINKED,
>>> +                       SEMANAGE_SEUSERS_LINKED,
>>> +                       SEMANAGE_USERS_EXTRA_LINKED};
>>> +
>>> +        for (i = 0; i < (int) sizeof(files); i++) {
>>> +            path = semanage_path(SEMANAGE_TMP, files[i]);
>>> +            if (stat(path, &sb) != 0) {
>>> +                if (errno != ENOENT) {
>>> +                    ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
>>> +                    goto cleanup;
>> Ditto
>>
>>> +                }
>>>   -        path = semanage_path(SEMANAGE_TMP, SEMANAGE_USERS_EXTRA_LINKED);
>>> -        if (access(path, F_OK) != 0) {
>>> -            do_rebuild = 1;
>>> -            goto rebuild;
>>> +                do_rebuild = 1;
>>> +                goto rebuild;
>>> +            }
>>>           }
>>>       }
>>>   @@ -1465,7 +1473,7 @@ rebuild:
>>>               goto cleanup;
>>>             path = semanage_path(SEMANAGE_TMP, SEMANAGE_SEUSERS_LINKED);
>>> -        if (access(path, F_OK) == 0) {
>>> +        if (stat(path, &sb) == 0) {
>>>               retval = semanage_copy_file(path,
>>>                               semanage_path(SEMANAGE_TMP,
>>>                                     SEMANAGE_STORE_SEUSERS),
>>> @@ -1473,12 +1481,18 @@ rebuild:
>>>               if (retval < 0)
>>>                   goto cleanup;
>>>               pseusers->dtable->drop_cache(pseusers->dbase);
>>> -        } else {
>>> +        } else if (errno == ENOENT) {
>>> +            /* The file does not exist */
>>>               pseusers->dtable->clear(sh, pseusers->dbase);
>>> +        } else {
>>> +            ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
>>> +            goto cleanup;
>> Ditto
>>
>>>           }
>>>   +
>>> +
>>>           path = semanage_path(SEMANAGE_TMP, SEMANAGE_USERS_EXTRA_LINKED);
>>> -        if (access(path, F_OK) == 0) {
>>> +        if (stat(path, &sb) == 0) {
>>>               retval = semanage_copy_file(path,
>>>                               semanage_path(SEMANAGE_TMP,
>>>                                     SEMANAGE_USERS_EXTRA),
>>> @@ -1486,8 +1500,12 @@ rebuild:
>>>               if (retval < 0)
>>>                   goto cleanup;
>>>               pusers_extra->dtable->drop_cache(pusers_extra->dbase);
>>> -        } else {
>>> +        } else if (errno == ENOENT) {
>>> +            /* The file does not exist */
>>>               pusers_extra->dtable->clear(sh, pusers_extra->dbase);
>>> +        } else {
>>> +            ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
>>> +            goto cleanup;
>> Ditto
>>
>>>           }
>>>       }
>>>   @@ -1817,6 +1835,7 @@ static int semanage_direct_extract(semanage_handle_t * sh,
>>>       ssize_t _data_len;
>>>       char *_data;
>>>       int compressed;
>>> +    struct stat sb;
>>>         /* get path of module */
>>>       rc = semanage_module_get_path(
>>> @@ -1829,8 +1848,8 @@ static int semanage_direct_extract(semanage_handle_t * sh,
>>>           goto cleanup;
>>>       }
>>>   -    if (access(module_path, F_OK) != 0) {
>>> -        ERR(sh, "Module does not exist: %s", module_path);
>>> +    if (stat(module_path, &sb) != 0) {
>>> +        ERR(sh, "Unable to access %s: %s\n", module_path, strerror(errno));
>>>           rc = -1;
>>>           goto cleanup;
>>>       }
>>> @@ -1859,7 +1878,12 @@ static int semanage_direct_extract(semanage_handle_t * sh,
>>>           goto cleanup;
>>>       }
>>>   -    if (extract_cil == 1 && strcmp(_modinfo->lang_ext, "cil") && access(input_file, F_OK) != 0) {
>>> +    if (extract_cil == 1 && strcmp(_modinfo->lang_ext, "cil") && stat(input_file, &sb) != 0) {
>>> +        if (errno != ENOENT) {
>>> +            ERR(sh, "Unable to access %s: %s\n", input_file, strerror(errno));
>> Ditto
>>
>>> +            goto cleanup;
>>> +   
>>> +
>>>           rc = semanage_compile_module(sh, _modinfo);
>>>           if (rc < 0) {
>>>               goto cleanup;
>>> @@ -2004,6 +2028,12 @@ static int semanage_direct_get_enabled(semanage_handle_t *sh,
>>>       }
>>>         if (stat(path, &sb) < 0) {
>>> +        if (errno != ENOENT) {
>>> +            ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
>>> +            status = -1;
>>> +            goto cleanup;
>>> +        }
>>> +
>>>           *enabled = 1;
>>>       }
>>>       else {
>>> @@ -2330,6 +2360,12 @@ static int semanage_direct_get_module_info(semanage_handle_t *sh,
>>>         /* set enabled/disabled status */
>>>       if (stat(fn, &sb) < 0) {
>>> +        if (errno != ENOENT) {
>>> +            ERR(sh, "Unable to access %s: %s\n", fn, strerror(errno));
>>> +            status = -1;
>>> +            goto cleanup;
>>> +        }
>>> +
>>>           ret = semanage_module_info_set_enabled(sh, *modinfo, 1);
>>>           if (ret != 0) {
>>>               status = -1;
>>> @@ -2738,6 +2774,7 @@ static int semanage_direct_install_info(semanage_handle_t *sh,
>>>       int status = 0;
>>>       int ret = 0;
>>>       int type;
>>> +    struct stat sb;
>>>         char path[PATH_MAX];
>>>       mode_t mask = umask(0077);
>>> @@ -2838,7 +2875,7 @@ static int semanage_direct_install_info(semanage_handle_t *sh,
>>>               goto cleanup;
>>>           }
>>>   -        if (access(path, F_OK) == 0) {
>>> +        if (stat(path, &sb) == 0) {
>>>               ret = unlink(path);
>>>               if (ret != 0) {
>>>                   ERR(sh, "Error while removing cached CIL file %s: %s", path, strerror(errno));
>>> diff --git a/libsemanage/src/semanage_store.c b/libsemanage/src/semanage_store.c
>>> index 4bd1d651..10f8b306 100644
>>> --- a/libsemanage/src/semanage_store.c
>>> +++ b/libsemanage/src/semanage_store.c
>>> @@ -514,6 +514,7 @@ char *semanage_conf_path(void)
>>>   {
>>>       char *semanage_conf = NULL;
>>>       int len;
>>> +    struct stat sb;
>>>         len = strlen(semanage_root()) + strlen(selinux_path()) + strlen(SEMANAGE_CONF_FILE);
>>>       semanage_conf = calloc(len + 1, sizeof(char));
>>> @@ -522,7 +523,12 @@ char *semanage_conf_path(void)
>>>       snprintf(semanage_conf, len + 1, "%s%s%s", semanage_root(), selinux_path(),
>>>            SEMANAGE_CONF_FILE);
>>>   -    if (access(semanage_conf, R_OK) != 0) {
>>> +    if (stat(semanage_conf, &sb) != 0) {
>>> +        if (errno != ENOENT) {
>>> +            /* semanage_conf exists but can't be accessed */
>>> +            return NULL;
>> Not sure this is what we want. I think we'd just return semanage_conf here, and then let the caller fail when it tries to access it, so that we get a useful error message with the pathname.
>>
>>> +        }
>>> +
>>>           snprintf(semanage_conf, len + 1, "%s%s", selinux_path(), SEMANAGE_CONF_FILE);
>>>       }
>>>   @@ -1508,8 +1514,14 @@ int semanage_split_fc(semanage_handle_t * sh)
>>>   static int sefcontext_compile(semanage_handle_t * sh, const char *path) {
>>>         int r;
>>> +    struct stat sb;
>>> +
>>> +    if (stat(path, &sb) < 0) {
>>> +        if (errno != ENOENT) {
>>> +            ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
>>> +            return -1;
>>> +        }
>>>   -    if (access(path, F_OK) != 0) {
>>>           return 0;
>>>       }
>>>  
> 
> 

Re: [PATCH 3/3] libsemanage: replace access() checks to make setuid programs work

[Stephen Smalley]

On 03/09/2018 08:28 AM, Stephen Smalley wrote:
> On 03/09/2018 08:14 AM, Vit Mojzis wrote:
>>
>>
>> On 7.3.2018 15:59, Stephen Smalley wrote:
>>> On 03/06/2018 06:58 AM, Vit Mojzis wrote:
>>>> access() uses real UID instead of effective UID which causes false
>>>> negative checks in setuid programs.
>>>> Replace access(,F_OK) (i.e. tests for file existence) by stat().
>>>> And access(,R_OK) by fopen(,"r")
>>>>
>>>> Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1186431
>>>>
>>>> Signed-off-by: Vit Mojzis <vmojzis@redhat.com>
>>>> ---
>>>>   libsemanage/src/direct_api.c     | 133 +++++++++++++++++++++++++--------------
>>>>   libsemanage/src/semanage_store.c |  16 ++++-
>>>>   2 files changed, 99 insertions(+), 50 deletions(-)
>>>>
>>>> diff --git a/libsemanage/src/direct_api.c b/libsemanage/src/direct_api.c
>>>> index 49cac14f..4e2af810 100644
>>>> --- a/libsemanage/src/direct_api.c
>>>> +++ b/libsemanage/src/direct_api.c
>>>> @@ -140,6 +140,7 @@ int semanage_direct_is_managed(semanage_handle_t * sh)
>>>>   int semanage_direct_connect(semanage_handle_t * sh)
>>>>   {
>>>>       const char *path;
>>>> +    struct stat sb;
>>>>         if (semanage_check_init(sh, sh->conf->store_root_path))
>>>>           goto err;
>>>> @@ -302,10 +303,16 @@ int semanage_direct_connect(semanage_handle_t * sh)
>>>>         /* set the disable dontaudit value */
>>>>       path = semanage_path(SEMANAGE_ACTIVE, SEMANAGE_DISABLE_DONTAUDIT);
>>>> -    if (access(path, F_OK) == 0)
>>>> +
>>>> +    if (stat(path, &sb) == 0)
>>>>           sepol_set_disable_dontaudit(sh->sepolh, 1);
>>>> -    else
>>>> +    else if (errno == ENOENT) {
>>>> +        /* The file does not exist */
>>>>           sepol_set_disable_dontaudit(sh->sepolh, 0);
>>>> +    } else {
>>>> +        ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
>>>> +        goto err;
>>>> +    }
>>>>         return STATUS_SUCCESS;
>>>>   @@ -1139,6 +1146,7 @@ static int semanage_compile_hll_modules(semanage_handle_t *sh,
>>>>       int status = 0;
>>>>       int i;
>>>>       char cil_path[PATH_MAX];
>>>> +    struct stat sb;
>>>>         assert(sh);
>>>>       assert(modinfos);
>>>> @@ -1155,9 +1163,13 @@ static int semanage_compile_hll_modules(semanage_handle_t *sh,
>>>>           }
>>>>             if (semanage_get_ignore_module_cache(sh) == 0 &&
>>>> -                access(cil_path, F_OK) == 0) {
>>>> +                (status = stat(cil_path, &sb)) == 0) {
>>>>               continue;
>>>>           }
>>>> +        if (status != 0 && errno != ENOENT) {
>>>> +            ERR(sh, "Unable to access %s: %s\n", cil_path, strerror(errno));
>>>> +            goto cleanup; //an error in the "stat" call
>>>> +        }
>>>>             status = semanage_compile_module(sh, &modinfos[i]);
>>>>           if (status < 0) {
>>>> @@ -1196,6 +1208,7 @@ static int semanage_direct_commit(semanage_handle_t * sh)
>>>>       struct cil_db *cildb = NULL;
>>>>       semanage_module_info_t *modinfos = NULL;
>>>>       mode_t mask = umask(0077);
>>>> +    struct stat sb;
>>>>         int do_rebuild, do_write_kernel, do_install;
>>>>       int fcontexts_modified, ports_modified, seusers_modified,
>>>> @@ -1234,10 +1247,15 @@ static int semanage_direct_commit(semanage_handle_t * sh)
>>>>         /* Create or remove the disable_dontaudit flag file. */
>>>>       path = semanage_path(SEMANAGE_TMP, SEMANAGE_DISABLE_DONTAUDIT);
>>>> -    if (access(path, F_OK) == 0)
>>>> +    if (stat(path, &sb) == 0)
>>>>           do_rebuild |= !(sepol_get_disable_dontaudit(sh->sepolh) == 1);
>>>> -    else
>>>> +    else if (errno == ENOENT) {
>>>> +        /* The file does not exist */
>>>>           do_rebuild |= (sepol_get_disable_dontaudit(sh->sepolh) == 1);
>>>> +    } else {
>>>> +        ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
>>> We need to ensure that retval is set in all of these cases.  Safest to always set it before goto cleanup,
>>> either explicitly to -1 or to return value of stat() call above.
>> Thank you.
>> The retval is actually initialized to -1 (and stat() returns -1 for any error) so it's not necessary to set it here. It will be necessary a little bit down the road after the first assignment to retval, you're right.
>> Should I set it to -1 here anyway to make it less prone to breaking due to future changes in the code (what about the other ERR calls in this section of the code)?
> 
> Yes, I would do that for safety here and in any other case where we didn't just set retval and test it.  IOW, any case where we have:
> 	retval = foo(args);
> 	if (retval < 0) {
> 		ERR(...)
> 		goto cleanup;
> 	}
> is fine as is, but any case where we have:
> 	if (some-condition-other-than-retval-less-than-0) {
> 		ERR(...)
> 		goto cleanup;
> 	}
> likely ought to explicitly set retval.
> 
> If we have too many of those, then maybe we ought to have an err: label that sets retval to -1 explicitly and goto it instead.

That said, you don't have to fix cases that you didn't introduce in your patch; that's up to you, and you can fix pre-existing cases via a separate patch if desired.
> 
>>
>>>> +        goto cleanup;
>>>> +    }
>>>>       if (sepol_get_disable_dontaudit(sh->sepolh) == 1) {
>>>>           FILE *touch;
>>>>           touch = fopen(path, "w");
>>>> @@ -1259,10 +1277,16 @@ static int semanage_direct_commit(semanage_handle_t * sh)
>>>>         /* Create or remove the preserve_tunables flag file. */
>>>>       path = semanage_path(SEMANAGE_TMP, SEMANAGE_PRESERVE_TUNABLES);
>>>> -    if (access(path, F_OK) == 0)
>>>> +    if (stat(path, &sb) == 0)
>>>>           do_rebuild |= !(sepol_get_preserve_tunables(sh->sepolh) == 1);
>>>> -    else
>>>> +    else if (errno == ENOENT) {
>>>> +        /* The file does not exist */
>>>>           do_rebuild |= (sepol_get_preserve_tunables(sh->sepolh) == 1);
>>>> +    } else {
>>>> +        ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
>>>> +        goto cleanup;
>>>> +    }
>>> Ditto
>>>
>>>> +
>>>>       if (sepol_get_preserve_tunables(sh->sepolh) == 1) {
>>>>           FILE *touch;
>>>>           touch = fopen(path, "w");
>>>> @@ -1299,40 +1323,24 @@ static int semanage_direct_commit(semanage_handle_t * sh)
>>>>        * a rebuild.
>>>>        */
>>>>       if (!do_rebuild) {
>>>> -        path = semanage_path(SEMANAGE_TMP, SEMANAGE_STORE_KERNEL);
>>>> -        if (access(path, F_OK) != 0) {
>>>> -            do_rebuild = 1;
>>>> -            goto rebuild;
>>>> -        }
>>>> -
>>>> -        path = semanage_path(SEMANAGE_TMP, SEMANAGE_STORE_FC);
>>>> -        if (access(path, F_OK) != 0) {
>>>> -            do_rebuild = 1;
>>>> -            goto rebuild;
>>>> -        }
>>>> -
>>>> -        path = semanage_path(SEMANAGE_TMP, SEMANAGE_STORE_SEUSERS);
>>>> -        if (access(path, F_OK) != 0) {
>>>> -            do_rebuild = 1;
>>>> -            goto rebuild;
>>>> -        }
>>>> -
>>>> -        path = semanage_path(SEMANAGE_TMP, SEMANAGE_LINKED);
>>>> -        if (access(path, F_OK) != 0) {
>>>> -            do_rebuild = 1;
>>>> -            goto rebuild;
>>>> -        }
>>>> -
>>>> -        path = semanage_path(SEMANAGE_TMP, SEMANAGE_SEUSERS_LINKED);
>>>> -        if (access(path, F_OK) != 0) {
>>>> -            do_rebuild = 1;
>>>> -            goto rebuild;
>>>> -        }
>>>> +        int files[] = {SEMANAGE_STORE_KERNEL,
>>>> +                       SEMANAGE_STORE_FC,
>>>> +                       SEMANAGE_STORE_SEUSERS,
>>>> +                       SEMANAGE_LINKED,
>>>> +                       SEMANAGE_SEUSERS_LINKED,
>>>> +                       SEMANAGE_USERS_EXTRA_LINKED};
>>>> +
>>>> +        for (i = 0; i < (int) sizeof(files); i++) {
>>>> +            path = semanage_path(SEMANAGE_TMP, files[i]);
>>>> +            if (stat(path, &sb) != 0) {
>>>> +                if (errno != ENOENT) {
>>>> +                    ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
>>>> +                    goto cleanup;
>>> Ditto
>>>
>>>> +                }
>>>>   -        path = semanage_path(SEMANAGE_TMP, SEMANAGE_USERS_EXTRA_LINKED);
>>>> -        if (access(path, F_OK) != 0) {
>>>> -            do_rebuild = 1;
>>>> -            goto rebuild;
>>>> +                do_rebuild = 1;
>>>> +                goto rebuild;
>>>> +            }
>>>>           }
>>>>       }
>>>>   @@ -1465,7 +1473,7 @@ rebuild:
>>>>               goto cleanup;
>>>>             path = semanage_path(SEMANAGE_TMP, SEMANAGE_SEUSERS_LINKED);
>>>> -        if (access(path, F_OK) == 0) {
>>>> +        if (stat(path, &sb) == 0) {
>>>>               retval = semanage_copy_file(path,
>>>>                               semanage_path(SEMANAGE_TMP,
>>>>                                     SEMANAGE_STORE_SEUSERS),
>>>> @@ -1473,12 +1481,18 @@ rebuild:
>>>>               if (retval < 0)
>>>>                   goto cleanup;
>>>>               pseusers->dtable->drop_cache(pseusers->dbase);
>>>> -        } else {
>>>> +        } else if (errno == ENOENT) {
>>>> +            /* The file does not exist */
>>>>               pseusers->dtable->clear(sh, pseusers->dbase);
>>>> +        } else {
>>>> +            ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
>>>> +            goto cleanup;
>>> Ditto
>>>
>>>>           }
>>>>   +
>>>> +
>>>>           path = semanage_path(SEMANAGE_TMP, SEMANAGE_USERS_EXTRA_LINKED);
>>>> -        if (access(path, F_OK) == 0) {
>>>> +        if (stat(path, &sb) == 0) {
>>>>               retval = semanage_copy_file(path,
>>>>                               semanage_path(SEMANAGE_TMP,
>>>>                                     SEMANAGE_USERS_EXTRA),
>>>> @@ -1486,8 +1500,12 @@ rebuild:
>>>>               if (retval < 0)
>>>>                   goto cleanup;
>>>>               pusers_extra->dtable->drop_cache(pusers_extra->dbase);
>>>> -        } else {
>>>> +        } else if (errno == ENOENT) {
>>>> +            /* The file does not exist */
>>>>               pusers_extra->dtable->clear(sh, pusers_extra->dbase);
>>>> +        } else {
>>>> +            ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
>>>> +            goto cleanup;
>>> Ditto
>>>
>>>>           }
>>>>       }
>>>>   @@ -1817,6 +1835,7 @@ static int semanage_direct_extract(semanage_handle_t * sh,
>>>>       ssize_t _data_len;
>>>>       char *_data;
>>>>       int compressed;
>>>> +    struct stat sb;
>>>>         /* get path of module */
>>>>       rc = semanage_module_get_path(
>>>> @@ -1829,8 +1848,8 @@ static int semanage_direct_extract(semanage_handle_t * sh,
>>>>           goto cleanup;
>>>>       }
>>>>   -    if (access(module_path, F_OK) != 0) {
>>>> -        ERR(sh, "Module does not exist: %s", module_path);
>>>> +    if (stat(module_path, &sb) != 0) {
>>>> +        ERR(sh, "Unable to access %s: %s\n", module_path, strerror(errno));
>>>>           rc = -1;
>>>>           goto cleanup;
>>>>       }
>>>> @@ -1859,7 +1878,12 @@ static int semanage_direct_extract(semanage_handle_t * sh,
>>>>           goto cleanup;
>>>>       }
>>>>   -    if (extract_cil == 1 && strcmp(_modinfo->lang_ext, "cil") && access(input_file, F_OK) != 0) {
>>>> +    if (extract_cil == 1 && strcmp(_modinfo->lang_ext, "cil") && stat(input_file, &sb) != 0) {
>>>> +        if (errno != ENOENT) {
>>>> +            ERR(sh, "Unable to access %s: %s\n", input_file, strerror(errno));
>>> Ditto
>>>
>>>> +            goto cleanup;
>>>> +   
>>>> +
>>>>           rc = semanage_compile_module(sh, _modinfo);
>>>>           if (rc < 0) {
>>>>               goto cleanup;
>>>> @@ -2004,6 +2028,12 @@ static int semanage_direct_get_enabled(semanage_handle_t *sh,
>>>>       }
>>>>         if (stat(path, &sb) < 0) {
>>>> +        if (errno != ENOENT) {
>>>> +            ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
>>>> +            status = -1;
>>>> +            goto cleanup;
>>>> +        }
>>>> +
>>>>           *enabled = 1;
>>>>       }
>>>>       else {
>>>> @@ -2330,6 +2360,12 @@ static int semanage_direct_get_module_info(semanage_handle_t *sh,
>>>>         /* set enabled/disabled status */
>>>>       if (stat(fn, &sb) < 0) {
>>>> +        if (errno != ENOENT) {
>>>> +            ERR(sh, "Unable to access %s: %s\n", fn, strerror(errno));
>>>> +            status = -1;
>>>> +            goto cleanup;
>>>> +        }
>>>> +
>>>>           ret = semanage_module_info_set_enabled(sh, *modinfo, 1);
>>>>           if (ret != 0) {
>>>>               status = -1;
>>>> @@ -2738,6 +2774,7 @@ static int semanage_direct_install_info(semanage_handle_t *sh,
>>>>       int status = 0;
>>>>       int ret = 0;
>>>>       int type;
>>>> +    struct stat sb;
>>>>         char path[PATH_MAX];
>>>>       mode_t mask = umask(0077);
>>>> @@ -2838,7 +2875,7 @@ static int semanage_direct_install_info(semanage_handle_t *sh,
>>>>               goto cleanup;
>>>>           }
>>>>   -        if (access(path, F_OK) == 0) {
>>>> +        if (stat(path, &sb) == 0) {
>>>>               ret = unlink(path);
>>>>               if (ret != 0) {
>>>>                   ERR(sh, "Error while removing cached CIL file %s: %s", path, strerror(errno));
>>>> diff --git a/libsemanage/src/semanage_store.c b/libsemanage/src/semanage_store.c
>>>> index 4bd1d651..10f8b306 100644
>>>> --- a/libsemanage/src/semanage_store.c
>>>> +++ b/libsemanage/src/semanage_store.c
>>>> @@ -514,6 +514,7 @@ char *semanage_conf_path(void)
>>>>   {
>>>>       char *semanage_conf = NULL;
>>>>       int len;
>>>> +    struct stat sb;
>>>>         len = strlen(semanage_root()) + strlen(selinux_path()) + strlen(SEMANAGE_CONF_FILE);
>>>>       semanage_conf = calloc(len + 1, sizeof(char));
>>>> @@ -522,7 +523,12 @@ char *semanage_conf_path(void)
>>>>       snprintf(semanage_conf, len + 1, "%s%s%s", semanage_root(), selinux_path(),
>>>>            SEMANAGE_CONF_FILE);
>>>>   -    if (access(semanage_conf, R_OK) != 0) {
>>>> +    if (stat(semanage_conf, &sb) != 0) {
>>>> +        if (errno != ENOENT) {
>>>> +            /* semanage_conf exists but can't be accessed */
>>>> +            return NULL;
>>> Not sure this is what we want. I think we'd just return semanage_conf here, and then let the caller fail when it tries to access it, so that we get a useful error message with the pathname.
>>>
>>>> +        }
>>>> +
>>>>           snprintf(semanage_conf, len + 1, "%s%s", selinux_path(), SEMANAGE_CONF_FILE);
>>>>       }
>>>>   @@ -1508,8 +1514,14 @@ int semanage_split_fc(semanage_handle_t * sh)
>>>>   static int sefcontext_compile(semanage_handle_t * sh, const char *path) {
>>>>         int r;
>>>> +    struct stat sb;
>>>> +
>>>> +    if (stat(path, &sb) < 0) {
>>>> +        if (errno != ENOENT) {
>>>> +            ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
>>>> +            return -1;
>>>> +        }
>>>>   -    if (access(path, F_OK) != 0) {
>>>>           return 0;
>>>>       }
>>>>  
>>
>>
> 

[PATCH] libsemanage: replace access() checks to make setuid programs work

[Vit Mojzis]

access() uses real UID instead of effective UID which causes false
negative checks in setuid programs.
Replace access() calls (mostly tests for file existence) by stat().

Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1186431

Signed-off-by: Vit Mojzis <vmojzis@redhat.com>
---
 libsemanage/src/direct_api.c     | 137 +++++++++++++++++++++++++--------------
 libsemanage/src/semanage_store.c |  11 +++-
 2 files changed, 98 insertions(+), 50 deletions(-)

diff --git a/libsemanage/src/direct_api.c b/libsemanage/src/direct_api.c
index 92d7517d..439122df 100644
--- a/libsemanage/src/direct_api.c
+++ b/libsemanage/src/direct_api.c
@@ -140,6 +140,7 @@ int semanage_direct_is_managed(semanage_handle_t * sh)
 int semanage_direct_connect(semanage_handle_t * sh)
 {
 	const char *path;
+	struct stat sb;
 
 	if (semanage_check_init(sh, sh->conf->store_root_path))
 		goto err;
@@ -302,10 +303,16 @@ int semanage_direct_connect(semanage_handle_t * sh)
 
 	/* set the disable dontaudit value */
 	path = semanage_path(SEMANAGE_ACTIVE, SEMANAGE_DISABLE_DONTAUDIT);
-	if (access(path, F_OK) == 0)
+
+	if (stat(path, &sb) == 0)
 		sepol_set_disable_dontaudit(sh->sepolh, 1);
-	else
+	else if (errno == ENOENT) {
+		/* The file does not exist */
 		sepol_set_disable_dontaudit(sh->sepolh, 0);
+	} else {
+		ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
+		goto err;
+	}
 
 	return STATUS_SUCCESS;
 
@@ -1139,6 +1146,7 @@ static int semanage_compile_hll_modules(semanage_handle_t *sh,
 	int status = 0;
 	int i;
 	char cil_path[PATH_MAX];
+	struct stat sb;
 
 	assert(sh);
 	assert(modinfos);
@@ -1155,9 +1163,13 @@ static int semanage_compile_hll_modules(semanage_handle_t *sh,
 		}
 
 		if (semanage_get_ignore_module_cache(sh) == 0 &&
-				access(cil_path, F_OK) == 0) {
+				(status = stat(cil_path, &sb)) == 0) {
 			continue;
 		}
+		if (status != 0 && errno != ENOENT) {
+			ERR(sh, "Unable to access %s: %s\n", cil_path, strerror(errno));
+			goto cleanup; //an error in the "stat" call
+		}
 
 		status = semanage_compile_module(sh, &modinfos[i]);
 		if (status < 0) {
@@ -1196,6 +1208,7 @@ static int semanage_direct_commit(semanage_handle_t * sh)
 	struct cil_db *cildb = NULL;
 	semanage_module_info_t *modinfos = NULL;
 	mode_t mask = umask(0077);
+	struct stat sb;
 
 	int do_rebuild, do_write_kernel, do_install;
 	int fcontexts_modified, ports_modified, seusers_modified,
@@ -1234,10 +1247,16 @@ static int semanage_direct_commit(semanage_handle_t * sh)
 
 	/* Create or remove the disable_dontaudit flag file. */
 	path = semanage_path(SEMANAGE_TMP, SEMANAGE_DISABLE_DONTAUDIT);
-	if (access(path, F_OK) == 0)
+	if (stat(path, &sb) == 0)
 		do_rebuild |= !(sepol_get_disable_dontaudit(sh->sepolh) == 1);
-	else
+	else if (errno == ENOENT) {
+		/* The file does not exist */
 		do_rebuild |= (sepol_get_disable_dontaudit(sh->sepolh) == 1);
+	} else {
+		ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
+		retval = -1;
+		goto cleanup;
+	}
 	if (sepol_get_disable_dontaudit(sh->sepolh) == 1) {
 		FILE *touch;
 		touch = fopen(path, "w");
@@ -1259,10 +1278,17 @@ static int semanage_direct_commit(semanage_handle_t * sh)
 
 	/* Create or remove the preserve_tunables flag file. */
 	path = semanage_path(SEMANAGE_TMP, SEMANAGE_PRESERVE_TUNABLES);
-	if (access(path, F_OK) == 0)
+	if (stat(path, &sb) == 0)
 		do_rebuild |= !(sepol_get_preserve_tunables(sh->sepolh) == 1);
-	else
+	else if (errno == ENOENT) {
+		/* The file does not exist */
 		do_rebuild |= (sepol_get_preserve_tunables(sh->sepolh) == 1);
+	} else {
+		ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
+		retval = -1;
+		goto cleanup;
+	}
+
 	if (sepol_get_preserve_tunables(sh->sepolh) == 1) {
 		FILE *touch;
 		touch = fopen(path, "w");
@@ -1299,40 +1325,25 @@ static int semanage_direct_commit(semanage_handle_t * sh)
 	 * a rebuild.
 	 */
 	if (!do_rebuild) {
-		path = semanage_path(SEMANAGE_TMP, SEMANAGE_STORE_KERNEL);
-		if (access(path, F_OK) != 0) {
-			do_rebuild = 1;
-			goto rebuild;
-		}
-
-		path = semanage_path(SEMANAGE_TMP, SEMANAGE_STORE_FC);
-		if (access(path, F_OK) != 0) {
-			do_rebuild = 1;
-			goto rebuild;
-		}
-
-		path = semanage_path(SEMANAGE_TMP, SEMANAGE_STORE_SEUSERS);
-		if (access(path, F_OK) != 0) {
-			do_rebuild = 1;
-			goto rebuild;
-		}
-
-		path = semanage_path(SEMANAGE_TMP, SEMANAGE_LINKED);
-		if (access(path, F_OK) != 0) {
-			do_rebuild = 1;
-			goto rebuild;
-		}
-
-		path = semanage_path(SEMANAGE_TMP, SEMANAGE_SEUSERS_LINKED);
-		if (access(path, F_OK) != 0) {
-			do_rebuild = 1;
-			goto rebuild;
-		}
+		int files[] = {SEMANAGE_STORE_KERNEL,
+					   SEMANAGE_STORE_FC,
+					   SEMANAGE_STORE_SEUSERS,
+					   SEMANAGE_LINKED,
+					   SEMANAGE_SEUSERS_LINKED,
+					   SEMANAGE_USERS_EXTRA_LINKED};
+
+		for (i = 0; i < (int) sizeof(files); i++) {
+			path = semanage_path(SEMANAGE_TMP, files[i]);
+			if (stat(path, &sb) != 0) {
+				if (errno != ENOENT) {
+					ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
+					retval = -1;
+					goto cleanup;
+				}
 
-		path = semanage_path(SEMANAGE_TMP, SEMANAGE_USERS_EXTRA_LINKED);
-		if (access(path, F_OK) != 0) {
-			do_rebuild = 1;
-			goto rebuild;
+				do_rebuild = 1;
+				goto rebuild;
+			}
 		}
 	}
 
@@ -1465,7 +1476,7 @@ rebuild:
 			goto cleanup;
 
 		path = semanage_path(SEMANAGE_TMP, SEMANAGE_SEUSERS_LINKED);
-		if (access(path, F_OK) == 0) {
+		if (stat(path, &sb) == 0) {
 			retval = semanage_copy_file(path,
 						    semanage_path(SEMANAGE_TMP,
 								  SEMANAGE_STORE_SEUSERS),
@@ -1473,12 +1484,17 @@ rebuild:
 			if (retval < 0)
 				goto cleanup;
 			pseusers->dtable->drop_cache(pseusers->dbase);
-		} else {
+		} else if (errno == ENOENT) {
+			/* The file does not exist */
 			pseusers->dtable->clear(sh, pseusers->dbase);
+		} else {
+			ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
+			retval = -1;
+			goto cleanup;
 		}
 
 		path = semanage_path(SEMANAGE_TMP, SEMANAGE_USERS_EXTRA_LINKED);
-		if (access(path, F_OK) == 0) {
+		if (stat(path, &sb) == 0) {
 			retval = semanage_copy_file(path,
 						    semanage_path(SEMANAGE_TMP,
 								  SEMANAGE_USERS_EXTRA),
@@ -1486,8 +1502,13 @@ rebuild:
 			if (retval < 0)
 				goto cleanup;
 			pusers_extra->dtable->drop_cache(pusers_extra->dbase);
-		} else {
+		} else if (errno == ENOENT) {
+			/* The file does not exist */
 			pusers_extra->dtable->clear(sh, pusers_extra->dbase);
+		} else {
+			ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
+			retval = -1;
+			goto cleanup;
 		}
 	}
 
@@ -1817,6 +1838,7 @@ static int semanage_direct_extract(semanage_handle_t * sh,
 	ssize_t _data_len;
 	char *_data;
 	int compressed;
+	struct stat sb;
 
 	/* get path of module */
 	rc = semanage_module_get_path(
@@ -1829,8 +1851,8 @@ static int semanage_direct_extract(semanage_handle_t * sh,
 		goto cleanup;
 	}
 
-	if (access(module_path, F_OK) != 0) {
-		ERR(sh, "Module does not exist: %s", module_path);
+	if (stat(module_path, &sb) != 0) {
+		ERR(sh, "Unable to access %s: %s\n", module_path, strerror(errno));
 		rc = -1;
 		goto cleanup;
 	}
@@ -1859,7 +1881,13 @@ static int semanage_direct_extract(semanage_handle_t * sh,
 		goto cleanup;
 	}
 
-	if (extract_cil == 1 && strcmp(_modinfo->lang_ext, "cil") && access(input_file, F_OK) != 0) {
+	if (extract_cil == 1 && strcmp(_modinfo->lang_ext, "cil") && stat(input_file, &sb) != 0) {
+		if (errno != ENOENT) {
+			ERR(sh, "Unable to access %s: %s\n", input_file, strerror(errno));
+			rc = -1;
+			goto cleanup;
+		}
+
 		rc = semanage_compile_module(sh, _modinfo);
 		if (rc < 0) {
 			goto cleanup;
@@ -2004,6 +2032,12 @@ static int semanage_direct_get_enabled(semanage_handle_t *sh,
 	}
 
 	if (stat(path, &sb) < 0) {
+		if (errno != ENOENT) {
+			ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
+			status = -1;
+			goto cleanup;
+		}
+
 		*enabled = 1;
 	}
 	else {
@@ -2330,6 +2364,12 @@ static int semanage_direct_get_module_info(semanage_handle_t *sh,
 
 	/* set enabled/disabled status */
 	if (stat(fn, &sb) < 0) {
+		if (errno != ENOENT) {
+			ERR(sh, "Unable to access %s: %s\n", fn, strerror(errno));
+			status = -1;
+			goto cleanup;
+		}
+
 		ret = semanage_module_info_set_enabled(sh, *modinfo, 1);
 		if (ret != 0) {
 			status = -1;
@@ -2738,6 +2778,7 @@ static int semanage_direct_install_info(semanage_handle_t *sh,
 	int status = 0;
 	int ret = 0;
 	int type;
+	struct stat sb;
 
 	char path[PATH_MAX];
 	mode_t mask = umask(0077);
@@ -2838,7 +2879,7 @@ static int semanage_direct_install_info(semanage_handle_t *sh,
 			goto cleanup;
 		}
 
-		if (access(path, F_OK) == 0) {
+		if (stat(path, &sb) == 0) {
 			ret = unlink(path);
 			if (ret != 0) {
 				ERR(sh, "Error while removing cached CIL file %s: %s", path, strerror(errno));
diff --git a/libsemanage/src/semanage_store.c b/libsemanage/src/semanage_store.c
index 4bd1d651..1e71ab67 100644
--- a/libsemanage/src/semanage_store.c
+++ b/libsemanage/src/semanage_store.c
@@ -514,6 +514,7 @@ char *semanage_conf_path(void)
 {
 	char *semanage_conf = NULL;
 	int len;
+	struct stat sb;
 
 	len = strlen(semanage_root()) + strlen(selinux_path()) + strlen(SEMANAGE_CONF_FILE);
 	semanage_conf = calloc(len + 1, sizeof(char));
@@ -522,7 +523,7 @@ char *semanage_conf_path(void)
 	snprintf(semanage_conf, len + 1, "%s%s%s", semanage_root(), selinux_path(),
 		 SEMANAGE_CONF_FILE);
 
-	if (access(semanage_conf, R_OK) != 0) {
+	if (stat(semanage_conf, &sb) != 0 && errno == ENONET) {
 		snprintf(semanage_conf, len + 1, "%s%s", selinux_path(), SEMANAGE_CONF_FILE);
 	}
 
@@ -1508,8 +1509,14 @@ int semanage_split_fc(semanage_handle_t * sh)
 static int sefcontext_compile(semanage_handle_t * sh, const char *path) {
 
 	int r;
+	struct stat sb;
+
+	if (stat(path, &sb) < 0) {
+		if (errno != ENOENT) {
+			ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
+			return -1;
+		}
 
-	if (access(path, F_OK) != 0) {
 		return 0;
 	}
 
-- 
2.14.3

Re: [PATCH] libsemanage: replace access() checks to make setuid programs work

[Stephen Smalley]

On 03/09/2018 10:21 AM, Vit Mojzis wrote:
> access() uses real UID instead of effective UID which causes false
> negative checks in setuid programs.
> Replace access() calls (mostly tests for file existence) by stat().
> 
> Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1186431
> 
> Signed-off-by: Vit Mojzis <vmojzis@redhat.com>
> ---
>  libsemanage/src/direct_api.c     | 137 +++++++++++++++++++++++++--------------
>  libsemanage/src/semanage_store.c |  11 +++-
>  2 files changed, 98 insertions(+), 50 deletions(-)
> 
> diff --git a/libsemanage/src/direct_api.c b/libsemanage/src/direct_api.c
> index 92d7517d..439122df 100644
> --- a/libsemanage/src/direct_api.c
> +++ b/libsemanage/src/direct_api.c
> @@ -140,6 +140,7 @@ int semanage_direct_is_managed(semanage_handle_t * sh)
>  int semanage_direct_connect(semanage_handle_t * sh)
>  {
>  	const char *path;
> +	struct stat sb;
>  
>  	if (semanage_check_init(sh, sh->conf->store_root_path))
>  		goto err;
> @@ -302,10 +303,16 @@ int semanage_direct_connect(semanage_handle_t * sh)
>  
>  	/* set the disable dontaudit value */
>  	path = semanage_path(SEMANAGE_ACTIVE, SEMANAGE_DISABLE_DONTAUDIT);
> -	if (access(path, F_OK) == 0)
> +
> +	if (stat(path, &sb) == 0)
>  		sepol_set_disable_dontaudit(sh->sepolh, 1);
> -	else
> +	else if (errno == ENOENT) {
> +		/* The file does not exist */
>  		sepol_set_disable_dontaudit(sh->sepolh, 0);
> +	} else {
> +		ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
> +		goto err;
> +	}
>  
>  	return STATUS_SUCCESS;
>  
> @@ -1139,6 +1146,7 @@ static int semanage_compile_hll_modules(semanage_handle_t *sh,
>  	int status = 0;
>  	int i;
>  	char cil_path[PATH_MAX];
> +	struct stat sb;
>  
>  	assert(sh);
>  	assert(modinfos);
> @@ -1155,9 +1163,13 @@ static int semanage_compile_hll_modules(semanage_handle_t *sh,
>  		}
>  
>  		if (semanage_get_ignore_module_cache(sh) == 0 &&
> -				access(cil_path, F_OK) == 0) {
> +				(status = stat(cil_path, &sb)) == 0) {
>  			continue;
>  		}
> +		if (status != 0 && errno != ENOENT) {
> +			ERR(sh, "Unable to access %s: %s\n", cil_path, strerror(errno));
> +			goto cleanup; //an error in the "stat" call
> +		}
>  
>  		status = semanage_compile_module(sh, &modinfos[i]);
>  		if (status < 0) {
> @@ -1196,6 +1208,7 @@ static int semanage_direct_commit(semanage_handle_t * sh)
>  	struct cil_db *cildb = NULL;
>  	semanage_module_info_t *modinfos = NULL;
>  	mode_t mask = umask(0077);
> +	struct stat sb;
>  
>  	int do_rebuild, do_write_kernel, do_install;
>  	int fcontexts_modified, ports_modified, seusers_modified,
> @@ -1234,10 +1247,16 @@ static int semanage_direct_commit(semanage_handle_t * sh)
>  
>  	/* Create or remove the disable_dontaudit flag file. */
>  	path = semanage_path(SEMANAGE_TMP, SEMANAGE_DISABLE_DONTAUDIT);
> -	if (access(path, F_OK) == 0)
> +	if (stat(path, &sb) == 0)
>  		do_rebuild |= !(sepol_get_disable_dontaudit(sh->sepolh) == 1);
> -	else
> +	else if (errno == ENOENT) {
> +		/* The file does not exist */
>  		do_rebuild |= (sepol_get_disable_dontaudit(sh->sepolh) == 1);
> +	} else {
> +		ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
> +		retval = -1;
> +		goto cleanup;
> +	}
>  	if (sepol_get_disable_dontaudit(sh->sepolh) == 1) {
>  		FILE *touch;
>  		touch = fopen(path, "w");
> @@ -1259,10 +1278,17 @@ static int semanage_direct_commit(semanage_handle_t * sh)
>  
>  	/* Create or remove the preserve_tunables flag file. */
>  	path = semanage_path(SEMANAGE_TMP, SEMANAGE_PRESERVE_TUNABLES);
> -	if (access(path, F_OK) == 0)
> +	if (stat(path, &sb) == 0)
>  		do_rebuild |= !(sepol_get_preserve_tunables(sh->sepolh) == 1);
> -	else
> +	else if (errno == ENOENT) {
> +		/* The file does not exist */
>  		do_rebuild |= (sepol_get_preserve_tunables(sh->sepolh) == 1);
> +	} else {
> +		ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
> +		retval = -1;
> +		goto cleanup;
> +	}
> +
>  	if (sepol_get_preserve_tunables(sh->sepolh) == 1) {
>  		FILE *touch;
>  		touch = fopen(path, "w");
> @@ -1299,40 +1325,25 @@ static int semanage_direct_commit(semanage_handle_t * sh)
>  	 * a rebuild.
>  	 */
>  	if (!do_rebuild) {
> -		path = semanage_path(SEMANAGE_TMP, SEMANAGE_STORE_KERNEL);
> -		if (access(path, F_OK) != 0) {
> -			do_rebuild = 1;
> -			goto rebuild;
> -		}
> -
> -		path = semanage_path(SEMANAGE_TMP, SEMANAGE_STORE_FC);
> -		if (access(path, F_OK) != 0) {
> -			do_rebuild = 1;
> -			goto rebuild;
> -		}
> -
> -		path = semanage_path(SEMANAGE_TMP, SEMANAGE_STORE_SEUSERS);
> -		if (access(path, F_OK) != 0) {
> -			do_rebuild = 1;
> -			goto rebuild;
> -		}
> -
> -		path = semanage_path(SEMANAGE_TMP, SEMANAGE_LINKED);
> -		if (access(path, F_OK) != 0) {
> -			do_rebuild = 1;
> -			goto rebuild;
> -		}
> -
> -		path = semanage_path(SEMANAGE_TMP, SEMANAGE_SEUSERS_LINKED);
> -		if (access(path, F_OK) != 0) {
> -			do_rebuild = 1;
> -			goto rebuild;
> -		}
> +		int files[] = {SEMANAGE_STORE_KERNEL,
> +					   SEMANAGE_STORE_FC,
> +					   SEMANAGE_STORE_SEUSERS,
> +					   SEMANAGE_LINKED,
> +					   SEMANAGE_SEUSERS_LINKED,
> +					   SEMANAGE_USERS_EXTRA_LINKED};
> +
> +		for (i = 0; i < (int) sizeof(files); i++) {
> +			path = semanage_path(SEMANAGE_TMP, files[i]);
> +			if (stat(path, &sb) != 0) {
> +				if (errno != ENOENT) {
> +					ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
> +					retval = -1;
> +					goto cleanup;
> +				}
>  
> -		path = semanage_path(SEMANAGE_TMP, SEMANAGE_USERS_EXTRA_LINKED);
> -		if (access(path, F_OK) != 0) {
> -			do_rebuild = 1;
> -			goto rebuild;
> +				do_rebuild = 1;
> +				goto rebuild;
> +			}
>  		}
>  	}
>  
> @@ -1465,7 +1476,7 @@ rebuild:
>  			goto cleanup;
>  
>  		path = semanage_path(SEMANAGE_TMP, SEMANAGE_SEUSERS_LINKED);
> -		if (access(path, F_OK) == 0) {
> +		if (stat(path, &sb) == 0) {
>  			retval = semanage_copy_file(path,
>  						    semanage_path(SEMANAGE_TMP,
>  								  SEMANAGE_STORE_SEUSERS),
> @@ -1473,12 +1484,17 @@ rebuild:
>  			if (retval < 0)
>  				goto cleanup;
>  			pseusers->dtable->drop_cache(pseusers->dbase);
> -		} else {
> +		} else if (errno == ENOENT) {
> +			/* The file does not exist */
>  			pseusers->dtable->clear(sh, pseusers->dbase);
> +		} else {
> +			ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
> +			retval = -1;
> +			goto cleanup;
>  		}
>  
>  		path = semanage_path(SEMANAGE_TMP, SEMANAGE_USERS_EXTRA_LINKED);
> -		if (access(path, F_OK) == 0) {
> +		if (stat(path, &sb) == 0) {
>  			retval = semanage_copy_file(path,
>  						    semanage_path(SEMANAGE_TMP,
>  								  SEMANAGE_USERS_EXTRA),
> @@ -1486,8 +1502,13 @@ rebuild:
>  			if (retval < 0)
>  				goto cleanup;
>  			pusers_extra->dtable->drop_cache(pusers_extra->dbase);
> -		} else {
> +		} else if (errno == ENOENT) {
> +			/* The file does not exist */
>  			pusers_extra->dtable->clear(sh, pusers_extra->dbase);
> +		} else {
> +			ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
> +			retval = -1;
> +			goto cleanup;
>  		}
>  	}
>  
> @@ -1817,6 +1838,7 @@ static int semanage_direct_extract(semanage_handle_t * sh,
>  	ssize_t _data_len;
>  	char *_data;
>  	int compressed;
> +	struct stat sb;
>  
>  	/* get path of module */
>  	rc = semanage_module_get_path(
> @@ -1829,8 +1851,8 @@ static int semanage_direct_extract(semanage_handle_t * sh,
>  		goto cleanup;
>  	}
>  
> -	if (access(module_path, F_OK) != 0) {
> -		ERR(sh, "Module does not exist: %s", module_path);
> +	if (stat(module_path, &sb) != 0) {
> +		ERR(sh, "Unable to access %s: %s\n", module_path, strerror(errno));
>  		rc = -1;
>  		goto cleanup;
>  	}
> @@ -1859,7 +1881,13 @@ static int semanage_direct_extract(semanage_handle_t * sh,
>  		goto cleanup;
>  	}
>  
> -	if (extract_cil == 1 && strcmp(_modinfo->lang_ext, "cil") && access(input_file, F_OK) != 0) {
> +	if (extract_cil == 1 && strcmp(_modinfo->lang_ext, "cil") && stat(input_file, &sb) != 0) {
> +		if (errno != ENOENT) {
> +			ERR(sh, "Unable to access %s: %s\n", input_file, strerror(errno));
> +			rc = -1;
> +			goto cleanup;
> +		}
> +
>  		rc = semanage_compile_module(sh, _modinfo);
>  		if (rc < 0) {
>  			goto cleanup;
> @@ -2004,6 +2032,12 @@ static int semanage_direct_get_enabled(semanage_handle_t *sh,
>  	}
>  
>  	if (stat(path, &sb) < 0) {
> +		if (errno != ENOENT) {
> +			ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
> +			status = -1;
> +			goto cleanup;
> +		}
> +
>  		*enabled = 1;
>  	}
>  	else {
> @@ -2330,6 +2364,12 @@ static int semanage_direct_get_module_info(semanage_handle_t *sh,
>  
>  	/* set enabled/disabled status */
>  	if (stat(fn, &sb) < 0) {
> +		if (errno != ENOENT) {
> +			ERR(sh, "Unable to access %s: %s\n", fn, strerror(errno));
> +			status = -1;
> +			goto cleanup;
> +		}
> +
>  		ret = semanage_module_info_set_enabled(sh, *modinfo, 1);
>  		if (ret != 0) {
>  			status = -1;
> @@ -2738,6 +2778,7 @@ static int semanage_direct_install_info(semanage_handle_t *sh,
>  	int status = 0;
>  	int ret = 0;
>  	int type;
> +	struct stat sb;
>  
>  	char path[PATH_MAX];
>  	mode_t mask = umask(0077);
> @@ -2838,7 +2879,7 @@ static int semanage_direct_install_info(semanage_handle_t *sh,
>  			goto cleanup;
>  		}
>  
> -		if (access(path, F_OK) == 0) {
> +		if (stat(path, &sb) == 0) {
>  			ret = unlink(path);
>  			if (ret != 0) {
>  				ERR(sh, "Error while removing cached CIL file %s: %s", path, strerror(errno));
> diff --git a/libsemanage/src/semanage_store.c b/libsemanage/src/semanage_store.c
> index 4bd1d651..1e71ab67 100644
> --- a/libsemanage/src/semanage_store.c
> +++ b/libsemanage/src/semanage_store.c
> @@ -514,6 +514,7 @@ char *semanage_conf_path(void)
>  {
>  	char *semanage_conf = NULL;
>  	int len;
> +	struct stat sb;
>  
>  	len = strlen(semanage_root()) + strlen(selinux_path()) + strlen(SEMANAGE_CONF_FILE);
>  	semanage_conf = calloc(len + 1, sizeof(char));
> @@ -522,7 +523,7 @@ char *semanage_conf_path(void)
>  	snprintf(semanage_conf, len + 1, "%s%s%s", semanage_root(), selinux_path(),
>  		 SEMANAGE_CONF_FILE);
>  
> -	if (access(semanage_conf, R_OK) != 0) {
> +	if (stat(semanage_conf, &sb) != 0 && errno == ENONET) {

Typo: ENONET vs ENOENT.

>  		snprintf(semanage_conf, len + 1, "%s%s", selinux_path(), SEMANAGE_CONF_FILE);
>  	}
>  
> @@ -1508,8 +1509,14 @@ int semanage_split_fc(semanage_handle_t * sh)
>  static int sefcontext_compile(semanage_handle_t * sh, const char *path) {
>  
>  	int r;
> +	struct stat sb;
> +
> +	if (stat(path, &sb) < 0) {
> +		if (errno != ENOENT) {
> +			ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
> +			return -1;
> +		}
>  
> -	if (access(path, F_OK) != 0) {
>  		return 0;
>  	}
>  
> 

[PATCH] libsemanage: replace access() checks to make setuid programs work

[Vit Mojzis]

access() uses real UID instead of effective UID which causes false
negative checks in setuid programs.
Replace access() calls (mostly tests for file existence) by stat().

Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1186431

Signed-off-by: Vit Mojzis <vmojzis@redhat.com>
---
 libsemanage/src/direct_api.c     | 137 +++++++++++++++++++++++++--------------
 libsemanage/src/semanage_store.c |  11 +++-
 2 files changed, 98 insertions(+), 50 deletions(-)

diff --git a/libsemanage/src/direct_api.c b/libsemanage/src/direct_api.c
index 92d7517d..439122df 100644
--- a/libsemanage/src/direct_api.c
+++ b/libsemanage/src/direct_api.c
@@ -140,6 +140,7 @@ int semanage_direct_is_managed(semanage_handle_t * sh)
 int semanage_direct_connect(semanage_handle_t * sh)
 {
 	const char *path;
+	struct stat sb;
 
 	if (semanage_check_init(sh, sh->conf->store_root_path))
 		goto err;
@@ -302,10 +303,16 @@ int semanage_direct_connect(semanage_handle_t * sh)
 
 	/* set the disable dontaudit value */
 	path = semanage_path(SEMANAGE_ACTIVE, SEMANAGE_DISABLE_DONTAUDIT);
-	if (access(path, F_OK) == 0)
+
+	if (stat(path, &sb) == 0)
 		sepol_set_disable_dontaudit(sh->sepolh, 1);
-	else
+	else if (errno == ENOENT) {
+		/* The file does not exist */
 		sepol_set_disable_dontaudit(sh->sepolh, 0);
+	} else {
+		ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
+		goto err;
+	}
 
 	return STATUS_SUCCESS;
 
@@ -1139,6 +1146,7 @@ static int semanage_compile_hll_modules(semanage_handle_t *sh,
 	int status = 0;
 	int i;
 	char cil_path[PATH_MAX];
+	struct stat sb;
 
 	assert(sh);
 	assert(modinfos);
@@ -1155,9 +1163,13 @@ static int semanage_compile_hll_modules(semanage_handle_t *sh,
 		}
 
 		if (semanage_get_ignore_module_cache(sh) == 0 &&
-				access(cil_path, F_OK) == 0) {
+				(status = stat(cil_path, &sb)) == 0) {
 			continue;
 		}
+		if (status != 0 && errno != ENOENT) {
+			ERR(sh, "Unable to access %s: %s\n", cil_path, strerror(errno));
+			goto cleanup; //an error in the "stat" call
+		}
 
 		status = semanage_compile_module(sh, &modinfos[i]);
 		if (status < 0) {
@@ -1196,6 +1208,7 @@ static int semanage_direct_commit(semanage_handle_t * sh)
 	struct cil_db *cildb = NULL;
 	semanage_module_info_t *modinfos = NULL;
 	mode_t mask = umask(0077);
+	struct stat sb;
 
 	int do_rebuild, do_write_kernel, do_install;
 	int fcontexts_modified, ports_modified, seusers_modified,
@@ -1234,10 +1247,16 @@ static int semanage_direct_commit(semanage_handle_t * sh)
 
 	/* Create or remove the disable_dontaudit flag file. */
 	path = semanage_path(SEMANAGE_TMP, SEMANAGE_DISABLE_DONTAUDIT);
-	if (access(path, F_OK) == 0)
+	if (stat(path, &sb) == 0)
 		do_rebuild |= !(sepol_get_disable_dontaudit(sh->sepolh) == 1);
-	else
+	else if (errno == ENOENT) {
+		/* The file does not exist */
 		do_rebuild |= (sepol_get_disable_dontaudit(sh->sepolh) == 1);
+	} else {
+		ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
+		retval = -1;
+		goto cleanup;
+	}
 	if (sepol_get_disable_dontaudit(sh->sepolh) == 1) {
 		FILE *touch;
 		touch = fopen(path, "w");
@@ -1259,10 +1278,17 @@ static int semanage_direct_commit(semanage_handle_t * sh)
 
 	/* Create or remove the preserve_tunables flag file. */
 	path = semanage_path(SEMANAGE_TMP, SEMANAGE_PRESERVE_TUNABLES);
-	if (access(path, F_OK) == 0)
+	if (stat(path, &sb) == 0)
 		do_rebuild |= !(sepol_get_preserve_tunables(sh->sepolh) == 1);
-	else
+	else if (errno == ENOENT) {
+		/* The file does not exist */
 		do_rebuild |= (sepol_get_preserve_tunables(sh->sepolh) == 1);
+	} else {
+		ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
+		retval = -1;
+		goto cleanup;
+	}
+
 	if (sepol_get_preserve_tunables(sh->sepolh) == 1) {
 		FILE *touch;
 		touch = fopen(path, "w");
@@ -1299,40 +1325,25 @@ static int semanage_direct_commit(semanage_handle_t * sh)
 	 * a rebuild.
 	 */
 	if (!do_rebuild) {
-		path = semanage_path(SEMANAGE_TMP, SEMANAGE_STORE_KERNEL);
-		if (access(path, F_OK) != 0) {
-			do_rebuild = 1;
-			goto rebuild;
-		}
-
-		path = semanage_path(SEMANAGE_TMP, SEMANAGE_STORE_FC);
-		if (access(path, F_OK) != 0) {
-			do_rebuild = 1;
-			goto rebuild;
-		}
-
-		path = semanage_path(SEMANAGE_TMP, SEMANAGE_STORE_SEUSERS);
-		if (access(path, F_OK) != 0) {
-			do_rebuild = 1;
-			goto rebuild;
-		}
-
-		path = semanage_path(SEMANAGE_TMP, SEMANAGE_LINKED);
-		if (access(path, F_OK) != 0) {
-			do_rebuild = 1;
-			goto rebuild;
-		}
-
-		path = semanage_path(SEMANAGE_TMP, SEMANAGE_SEUSERS_LINKED);
-		if (access(path, F_OK) != 0) {
-			do_rebuild = 1;
-			goto rebuild;
-		}
+		int files[] = {SEMANAGE_STORE_KERNEL,
+					   SEMANAGE_STORE_FC,
+					   SEMANAGE_STORE_SEUSERS,
+					   SEMANAGE_LINKED,
+					   SEMANAGE_SEUSERS_LINKED,
+					   SEMANAGE_USERS_EXTRA_LINKED};
+
+		for (i = 0; i < (int) sizeof(files); i++) {
+			path = semanage_path(SEMANAGE_TMP, files[i]);
+			if (stat(path, &sb) != 0) {
+				if (errno != ENOENT) {
+					ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
+					retval = -1;
+					goto cleanup;
+				}
 
-		path = semanage_path(SEMANAGE_TMP, SEMANAGE_USERS_EXTRA_LINKED);
-		if (access(path, F_OK) != 0) {
-			do_rebuild = 1;
-			goto rebuild;
+				do_rebuild = 1;
+				goto rebuild;
+			}
 		}
 	}
 
@@ -1465,7 +1476,7 @@ rebuild:
 			goto cleanup;
 
 		path = semanage_path(SEMANAGE_TMP, SEMANAGE_SEUSERS_LINKED);
-		if (access(path, F_OK) == 0) {
+		if (stat(path, &sb) == 0) {
 			retval = semanage_copy_file(path,
 						    semanage_path(SEMANAGE_TMP,
 								  SEMANAGE_STORE_SEUSERS),
@@ -1473,12 +1484,17 @@ rebuild:
 			if (retval < 0)
 				goto cleanup;
 			pseusers->dtable->drop_cache(pseusers->dbase);
-		} else {
+		} else if (errno == ENOENT) {
+			/* The file does not exist */
 			pseusers->dtable->clear(sh, pseusers->dbase);
+		} else {
+			ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
+			retval = -1;
+			goto cleanup;
 		}
 
 		path = semanage_path(SEMANAGE_TMP, SEMANAGE_USERS_EXTRA_LINKED);
-		if (access(path, F_OK) == 0) {
+		if (stat(path, &sb) == 0) {
 			retval = semanage_copy_file(path,
 						    semanage_path(SEMANAGE_TMP,
 								  SEMANAGE_USERS_EXTRA),
@@ -1486,8 +1502,13 @@ rebuild:
 			if (retval < 0)
 				goto cleanup;
 			pusers_extra->dtable->drop_cache(pusers_extra->dbase);
-		} else {
+		} else if (errno == ENOENT) {
+			/* The file does not exist */
 			pusers_extra->dtable->clear(sh, pusers_extra->dbase);
+		} else {
+			ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
+			retval = -1;
+			goto cleanup;
 		}
 	}
 
@@ -1817,6 +1838,7 @@ static int semanage_direct_extract(semanage_handle_t * sh,
 	ssize_t _data_len;
 	char *_data;
 	int compressed;
+	struct stat sb;
 
 	/* get path of module */
 	rc = semanage_module_get_path(
@@ -1829,8 +1851,8 @@ static int semanage_direct_extract(semanage_handle_t * sh,
 		goto cleanup;
 	}
 
-	if (access(module_path, F_OK) != 0) {
-		ERR(sh, "Module does not exist: %s", module_path);
+	if (stat(module_path, &sb) != 0) {
+		ERR(sh, "Unable to access %s: %s\n", module_path, strerror(errno));
 		rc = -1;
 		goto cleanup;
 	}
@@ -1859,7 +1881,13 @@ static int semanage_direct_extract(semanage_handle_t * sh,
 		goto cleanup;
 	}
 
-	if (extract_cil == 1 && strcmp(_modinfo->lang_ext, "cil") && access(input_file, F_OK) != 0) {
+	if (extract_cil == 1 && strcmp(_modinfo->lang_ext, "cil") && stat(input_file, &sb) != 0) {
+		if (errno != ENOENT) {
+			ERR(sh, "Unable to access %s: %s\n", input_file, strerror(errno));
+			rc = -1;
+			goto cleanup;
+		}
+
 		rc = semanage_compile_module(sh, _modinfo);
 		if (rc < 0) {
 			goto cleanup;
@@ -2004,6 +2032,12 @@ static int semanage_direct_get_enabled(semanage_handle_t *sh,
 	}
 
 	if (stat(path, &sb) < 0) {
+		if (errno != ENOENT) {
+			ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
+			status = -1;
+			goto cleanup;
+		}
+
 		*enabled = 1;
 	}
 	else {
@@ -2330,6 +2364,12 @@ static int semanage_direct_get_module_info(semanage_handle_t *sh,
 
 	/* set enabled/disabled status */
 	if (stat(fn, &sb) < 0) {
+		if (errno != ENOENT) {
+			ERR(sh, "Unable to access %s: %s\n", fn, strerror(errno));
+			status = -1;
+			goto cleanup;
+		}
+
 		ret = semanage_module_info_set_enabled(sh, *modinfo, 1);
 		if (ret != 0) {
 			status = -1;
@@ -2738,6 +2778,7 @@ static int semanage_direct_install_info(semanage_handle_t *sh,
 	int status = 0;
 	int ret = 0;
 	int type;
+	struct stat sb;
 
 	char path[PATH_MAX];
 	mode_t mask = umask(0077);
@@ -2838,7 +2879,7 @@ static int semanage_direct_install_info(semanage_handle_t *sh,
 			goto cleanup;
 		}
 
-		if (access(path, F_OK) == 0) {
+		if (stat(path, &sb) == 0) {
 			ret = unlink(path);
 			if (ret != 0) {
 				ERR(sh, "Error while removing cached CIL file %s: %s", path, strerror(errno));
diff --git a/libsemanage/src/semanage_store.c b/libsemanage/src/semanage_store.c
index 4bd1d651..14ad99c1 100644
--- a/libsemanage/src/semanage_store.c
+++ b/libsemanage/src/semanage_store.c
@@ -514,6 +514,7 @@ char *semanage_conf_path(void)
 {
 	char *semanage_conf = NULL;
 	int len;
+	struct stat sb;
 
 	len = strlen(semanage_root()) + strlen(selinux_path()) + strlen(SEMANAGE_CONF_FILE);
 	semanage_conf = calloc(len + 1, sizeof(char));
@@ -522,7 +523,7 @@ char *semanage_conf_path(void)
 	snprintf(semanage_conf, len + 1, "%s%s%s", semanage_root(), selinux_path(),
 		 SEMANAGE_CONF_FILE);
 
-	if (access(semanage_conf, R_OK) != 0) {
+	if (stat(semanage_conf, &sb) != 0 && errno == ENOENT) {
 		snprintf(semanage_conf, len + 1, "%s%s", selinux_path(), SEMANAGE_CONF_FILE);
 	}
 
@@ -1508,8 +1509,14 @@ int semanage_split_fc(semanage_handle_t * sh)
 static int sefcontext_compile(semanage_handle_t * sh, const char *path) {
 
 	int r;
+	struct stat sb;
+
+	if (stat(path, &sb) < 0) {
+		if (errno != ENOENT) {
+			ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
+			return -1;
+		}
 
-	if (access(path, F_OK) != 0) {
 		return 0;
 	}
 
-- 
2.14.3

Re: [PATCH] libsemanage: replace access() checks to make setuid programs work

[Stephen Smalley]

On 03/09/2018 10:39 AM, Vit Mojzis wrote:
> access() uses real UID instead of effective UID which causes false
> negative checks in setuid programs.
> Replace access() calls (mostly tests for file existence) by stat().
> 
> Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1186431

Thanks, I've put this up as a PR for testing here:
https://github.com/SELinuxProject/selinux/pull/84

I won't be around next week so someone else can merge it or I will get to it when I return.

> 
> Signed-off-by: Vit Mojzis <vmojzis@redhat.com>
> ---
>  libsemanage/src/direct_api.c     | 137 +++++++++++++++++++++++++--------------
>  libsemanage/src/semanage_store.c |  11 +++-
>  2 files changed, 98 insertions(+), 50 deletions(-)
> 
> diff --git a/libsemanage/src/direct_api.c b/libsemanage/src/direct_api.c
> index 92d7517d..439122df 100644
> --- a/libsemanage/src/direct_api.c
> +++ b/libsemanage/src/direct_api.c
> @@ -140,6 +140,7 @@ int semanage_direct_is_managed(semanage_handle_t * sh)
>  int semanage_direct_connect(semanage_handle_t * sh)
>  {
>  	const char *path;
> +	struct stat sb;
>  
>  	if (semanage_check_init(sh, sh->conf->store_root_path))
>  		goto err;
> @@ -302,10 +303,16 @@ int semanage_direct_connect(semanage_handle_t * sh)
>  
>  	/* set the disable dontaudit value */
>  	path = semanage_path(SEMANAGE_ACTIVE, SEMANAGE_DISABLE_DONTAUDIT);
> -	if (access(path, F_OK) == 0)
> +
> +	if (stat(path, &sb) == 0)
>  		sepol_set_disable_dontaudit(sh->sepolh, 1);
> -	else
> +	else if (errno == ENOENT) {
> +		/* The file does not exist */
>  		sepol_set_disable_dontaudit(sh->sepolh, 0);
> +	} else {
> +		ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
> +		goto err;
> +	}
>  
>  	return STATUS_SUCCESS;
>  
> @@ -1139,6 +1146,7 @@ static int semanage_compile_hll_modules(semanage_handle_t *sh,
>  	int status = 0;
>  	int i;
>  	char cil_path[PATH_MAX];
> +	struct stat sb;
>  
>  	assert(sh);
>  	assert(modinfos);
> @@ -1155,9 +1163,13 @@ static int semanage_compile_hll_modules(semanage_handle_t *sh,
>  		}
>  
>  		if (semanage_get_ignore_module_cache(sh) == 0 &&
> -				access(cil_path, F_OK) == 0) {
> +				(status = stat(cil_path, &sb)) == 0) {
>  			continue;
>  		}
> +		if (status != 0 && errno != ENOENT) {
> +			ERR(sh, "Unable to access %s: %s\n", cil_path, strerror(errno));
> +			goto cleanup; //an error in the "stat" call
> +		}
>  
>  		status = semanage_compile_module(sh, &modinfos[i]);
>  		if (status < 0) {
> @@ -1196,6 +1208,7 @@ static int semanage_direct_commit(semanage_handle_t * sh)
>  	struct cil_db *cildb = NULL;
>  	semanage_module_info_t *modinfos = NULL;
>  	mode_t mask = umask(0077);
> +	struct stat sb;
>  
>  	int do_rebuild, do_write_kernel, do_install;
>  	int fcontexts_modified, ports_modified, seusers_modified,
> @@ -1234,10 +1247,16 @@ static int semanage_direct_commit(semanage_handle_t * sh)
>  
>  	/* Create or remove the disable_dontaudit flag file. */
>  	path = semanage_path(SEMANAGE_TMP, SEMANAGE_DISABLE_DONTAUDIT);
> -	if (access(path, F_OK) == 0)
> +	if (stat(path, &sb) == 0)
>  		do_rebuild |= !(sepol_get_disable_dontaudit(sh->sepolh) == 1);
> -	else
> +	else if (errno == ENOENT) {
> +		/* The file does not exist */
>  		do_rebuild |= (sepol_get_disable_dontaudit(sh->sepolh) == 1);
> +	} else {
> +		ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
> +		retval = -1;
> +		goto cleanup;
> +	}
>  	if (sepol_get_disable_dontaudit(sh->sepolh) == 1) {
>  		FILE *touch;
>  		touch = fopen(path, "w");
> @@ -1259,10 +1278,17 @@ static int semanage_direct_commit(semanage_handle_t * sh)
>  
>  	/* Create or remove the preserve_tunables flag file. */
>  	path = semanage_path(SEMANAGE_TMP, SEMANAGE_PRESERVE_TUNABLES);
> -	if (access(path, F_OK) == 0)
> +	if (stat(path, &sb) == 0)
>  		do_rebuild |= !(sepol_get_preserve_tunables(sh->sepolh) == 1);
> -	else
> +	else if (errno == ENOENT) {
> +		/* The file does not exist */
>  		do_rebuild |= (sepol_get_preserve_tunables(sh->sepolh) == 1);
> +	} else {
> +		ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
> +		retval = -1;
> +		goto cleanup;
> +	}
> +
>  	if (sepol_get_preserve_tunables(sh->sepolh) == 1) {
>  		FILE *touch;
>  		touch = fopen(path, "w");
> @@ -1299,40 +1325,25 @@ static int semanage_direct_commit(semanage_handle_t * sh)
>  	 * a rebuild.
>  	 */
>  	if (!do_rebuild) {
> -		path = semanage_path(SEMANAGE_TMP, SEMANAGE_STORE_KERNEL);
> -		if (access(path, F_OK) != 0) {
> -			do_rebuild = 1;
> -			goto rebuild;
> -		}
> -
> -		path = semanage_path(SEMANAGE_TMP, SEMANAGE_STORE_FC);
> -		if (access(path, F_OK) != 0) {
> -			do_rebuild = 1;
> -			goto rebuild;
> -		}
> -
> -		path = semanage_path(SEMANAGE_TMP, SEMANAGE_STORE_SEUSERS);
> -		if (access(path, F_OK) != 0) {
> -			do_rebuild = 1;
> -			goto rebuild;
> -		}
> -
> -		path = semanage_path(SEMANAGE_TMP, SEMANAGE_LINKED);
> -		if (access(path, F_OK) != 0) {
> -			do_rebuild = 1;
> -			goto rebuild;
> -		}
> -
> -		path = semanage_path(SEMANAGE_TMP, SEMANAGE_SEUSERS_LINKED);
> -		if (access(path, F_OK) != 0) {
> -			do_rebuild = 1;
> -			goto rebuild;
> -		}
> +		int files[] = {SEMANAGE_STORE_KERNEL,
> +					   SEMANAGE_STORE_FC,
> +					   SEMANAGE_STORE_SEUSERS,
> +					   SEMANAGE_LINKED,
> +					   SEMANAGE_SEUSERS_LINKED,
> +					   SEMANAGE_USERS_EXTRA_LINKED};
> +
> +		for (i = 0; i < (int) sizeof(files); i++) {
> +			path = semanage_path(SEMANAGE_TMP, files[i]);
> +			if (stat(path, &sb) != 0) {
> +				if (errno != ENOENT) {
> +					ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
> +					retval = -1;
> +					goto cleanup;
> +				}
>  
> -		path = semanage_path(SEMANAGE_TMP, SEMANAGE_USERS_EXTRA_LINKED);
> -		if (access(path, F_OK) != 0) {
> -			do_rebuild = 1;
> -			goto rebuild;
> +				do_rebuild = 1;
> +				goto rebuild;
> +			}
>  		}
>  	}
>  
> @@ -1465,7 +1476,7 @@ rebuild:
>  			goto cleanup;
>  
>  		path = semanage_path(SEMANAGE_TMP, SEMANAGE_SEUSERS_LINKED);
> -		if (access(path, F_OK) == 0) {
> +		if (stat(path, &sb) == 0) {
>  			retval = semanage_copy_file(path,
>  						    semanage_path(SEMANAGE_TMP,
>  								  SEMANAGE_STORE_SEUSERS),
> @@ -1473,12 +1484,17 @@ rebuild:
>  			if (retval < 0)
>  				goto cleanup;
>  			pseusers->dtable->drop_cache(pseusers->dbase);
> -		} else {
> +		} else if (errno == ENOENT) {
> +			/* The file does not exist */
>  			pseusers->dtable->clear(sh, pseusers->dbase);
> +		} else {
> +			ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
> +			retval = -1;
> +			goto cleanup;
>  		}
>  
>  		path = semanage_path(SEMANAGE_TMP, SEMANAGE_USERS_EXTRA_LINKED);
> -		if (access(path, F_OK) == 0) {
> +		if (stat(path, &sb) == 0) {
>  			retval = semanage_copy_file(path,
>  						    semanage_path(SEMANAGE_TMP,
>  								  SEMANAGE_USERS_EXTRA),
> @@ -1486,8 +1502,13 @@ rebuild:
>  			if (retval < 0)
>  				goto cleanup;
>  			pusers_extra->dtable->drop_cache(pusers_extra->dbase);
> -		} else {
> +		} else if (errno == ENOENT) {
> +			/* The file does not exist */
>  			pusers_extra->dtable->clear(sh, pusers_extra->dbase);
> +		} else {
> +			ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
> +			retval = -1;
> +			goto cleanup;
>  		}
>  	}
>  
> @@ -1817,6 +1838,7 @@ static int semanage_direct_extract(semanage_handle_t * sh,
>  	ssize_t _data_len;
>  	char *_data;
>  	int compressed;
> +	struct stat sb;
>  
>  	/* get path of module */
>  	rc = semanage_module_get_path(
> @@ -1829,8 +1851,8 @@ static int semanage_direct_extract(semanage_handle_t * sh,
>  		goto cleanup;
>  	}
>  
> -	if (access(module_path, F_OK) != 0) {
> -		ERR(sh, "Module does not exist: %s", module_path);
> +	if (stat(module_path, &sb) != 0) {
> +		ERR(sh, "Unable to access %s: %s\n", module_path, strerror(errno));
>  		rc = -1;
>  		goto cleanup;
>  	}
> @@ -1859,7 +1881,13 @@ static int semanage_direct_extract(semanage_handle_t * sh,
>  		goto cleanup;
>  	}
>  
> -	if (extract_cil == 1 && strcmp(_modinfo->lang_ext, "cil") && access(input_file, F_OK) != 0) {
> +	if (extract_cil == 1 && strcmp(_modinfo->lang_ext, "cil") && stat(input_file, &sb) != 0) {
> +		if (errno != ENOENT) {
> +			ERR(sh, "Unable to access %s: %s\n", input_file, strerror(errno));
> +			rc = -1;
> +			goto cleanup;
> +		}
> +
>  		rc = semanage_compile_module(sh, _modinfo);
>  		if (rc < 0) {
>  			goto cleanup;
> @@ -2004,6 +2032,12 @@ static int semanage_direct_get_enabled(semanage_handle_t *sh,
>  	}
>  
>  	if (stat(path, &sb) < 0) {
> +		if (errno != ENOENT) {
> +			ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
> +			status = -1;
> +			goto cleanup;
> +		}
> +
>  		*enabled = 1;
>  	}
>  	else {
> @@ -2330,6 +2364,12 @@ static int semanage_direct_get_module_info(semanage_handle_t *sh,
>  
>  	/* set enabled/disabled status */
>  	if (stat(fn, &sb) < 0) {
> +		if (errno != ENOENT) {
> +			ERR(sh, "Unable to access %s: %s\n", fn, strerror(errno));
> +			status = -1;
> +			goto cleanup;
> +		}
> +
>  		ret = semanage_module_info_set_enabled(sh, *modinfo, 1);
>  		if (ret != 0) {
>  			status = -1;
> @@ -2738,6 +2778,7 @@ static int semanage_direct_install_info(semanage_handle_t *sh,
>  	int status = 0;
>  	int ret = 0;
>  	int type;
> +	struct stat sb;
>  
>  	char path[PATH_MAX];
>  	mode_t mask = umask(0077);
> @@ -2838,7 +2879,7 @@ static int semanage_direct_install_info(semanage_handle_t *sh,
>  			goto cleanup;
>  		}
>  
> -		if (access(path, F_OK) == 0) {
> +		if (stat(path, &sb) == 0) {
>  			ret = unlink(path);
>  			if (ret != 0) {
>  				ERR(sh, "Error while removing cached CIL file %s: %s", path, strerror(errno));
> diff --git a/libsemanage/src/semanage_store.c b/libsemanage/src/semanage_store.c
> index 4bd1d651..14ad99c1 100644
> --- a/libsemanage/src/semanage_store.c
> +++ b/libsemanage/src/semanage_store.c
> @@ -514,6 +514,7 @@ char *semanage_conf_path(void)
>  {
>  	char *semanage_conf = NULL;
>  	int len;
> +	struct stat sb;
>  
>  	len = strlen(semanage_root()) + strlen(selinux_path()) + strlen(SEMANAGE_CONF_FILE);
>  	semanage_conf = calloc(len + 1, sizeof(char));
> @@ -522,7 +523,7 @@ char *semanage_conf_path(void)
>  	snprintf(semanage_conf, len + 1, "%s%s%s", semanage_root(), selinux_path(),
>  		 SEMANAGE_CONF_FILE);
>  
> -	if (access(semanage_conf, R_OK) != 0) {
> +	if (stat(semanage_conf, &sb) != 0 && errno == ENOENT) {
>  		snprintf(semanage_conf, len + 1, "%s%s", selinux_path(), SEMANAGE_CONF_FILE);
>  	}
>  
> @@ -1508,8 +1509,14 @@ int semanage_split_fc(semanage_handle_t * sh)
>  static int sefcontext_compile(semanage_handle_t * sh, const char *path) {
>  
>  	int r;
> +	struct stat sb;
> +
> +	if (stat(path, &sb) < 0) {
> +		if (errno != ENOENT) {
> +			ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
> +			return -1;
> +		}
>  
> -	if (access(path, F_OK) != 0) {
>  		return 0;
>  	}
>  
> 

Re: [PATCH] libsemanage: replace access() checks to make setuid programs work

[Petr Lautrbach]

[-- Attachment #1: Type: text/plain, Size: 11950 bytes --]

On Fri, Mar 09, 2018 at 10:51:20AM -0500, Stephen Smalley wrote:
> On 03/09/2018 10:39 AM, Vit Mojzis wrote:
> > access() uses real UID instead of effective UID which causes false
> > negative checks in setuid programs.
> > Replace access() calls (mostly tests for file existence) by stat().
> > 
> > Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1186431
> 
> Thanks, I've put this up as a PR for testing here:
> https://github.com/SELinuxProject/selinux/pull/84
> 
> I won't be around next week so someone else can merge it or I will get to it when I return.

This is merged now. Thanks!

> > 
> > Signed-off-by: Vit Mojzis <vmojzis@redhat.com>
> > ---
> >  libsemanage/src/direct_api.c     | 137 +++++++++++++++++++++++++--------------
> >  libsemanage/src/semanage_store.c |  11 +++-
> >  2 files changed, 98 insertions(+), 50 deletions(-)
> > 
> > diff --git a/libsemanage/src/direct_api.c b/libsemanage/src/direct_api.c
> > index 92d7517d..439122df 100644
> > --- a/libsemanage/src/direct_api.c
> > +++ b/libsemanage/src/direct_api.c
> > @@ -140,6 +140,7 @@ int semanage_direct_is_managed(semanage_handle_t * sh)
> >  int semanage_direct_connect(semanage_handle_t * sh)
> >  {
> >  	const char *path;
> > +	struct stat sb;
> >  
> >  	if (semanage_check_init(sh, sh->conf->store_root_path))
> >  		goto err;
> > @@ -302,10 +303,16 @@ int semanage_direct_connect(semanage_handle_t * sh)
> >  
> >  	/* set the disable dontaudit value */
> >  	path = semanage_path(SEMANAGE_ACTIVE, SEMANAGE_DISABLE_DONTAUDIT);
> > -	if (access(path, F_OK) == 0)
> > +
> > +	if (stat(path, &sb) == 0)
> >  		sepol_set_disable_dontaudit(sh->sepolh, 1);
> > -	else
> > +	else if (errno == ENOENT) {
> > +		/* The file does not exist */
> >  		sepol_set_disable_dontaudit(sh->sepolh, 0);
> > +	} else {
> > +		ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
> > +		goto err;
> > +	}
> >  
> >  	return STATUS_SUCCESS;
> >  
> > @@ -1139,6 +1146,7 @@ static int semanage_compile_hll_modules(semanage_handle_t *sh,
> >  	int status = 0;
> >  	int i;
> >  	char cil_path[PATH_MAX];
> > +	struct stat sb;
> >  
> >  	assert(sh);
> >  	assert(modinfos);
> > @@ -1155,9 +1163,13 @@ static int semanage_compile_hll_modules(semanage_handle_t *sh,
> >  		}
> >  
> >  		if (semanage_get_ignore_module_cache(sh) == 0 &&
> > -				access(cil_path, F_OK) == 0) {
> > +				(status = stat(cil_path, &sb)) == 0) {
> >  			continue;
> >  		}
> > +		if (status != 0 && errno != ENOENT) {
> > +			ERR(sh, "Unable to access %s: %s\n", cil_path, strerror(errno));
> > +			goto cleanup; //an error in the "stat" call
> > +		}
> >  
> >  		status = semanage_compile_module(sh, &modinfos[i]);
> >  		if (status < 0) {
> > @@ -1196,6 +1208,7 @@ static int semanage_direct_commit(semanage_handle_t * sh)
> >  	struct cil_db *cildb = NULL;
> >  	semanage_module_info_t *modinfos = NULL;
> >  	mode_t mask = umask(0077);
> > +	struct stat sb;
> >  
> >  	int do_rebuild, do_write_kernel, do_install;
> >  	int fcontexts_modified, ports_modified, seusers_modified,
> > @@ -1234,10 +1247,16 @@ static int semanage_direct_commit(semanage_handle_t * sh)
> >  
> >  	/* Create or remove the disable_dontaudit flag file. */
> >  	path = semanage_path(SEMANAGE_TMP, SEMANAGE_DISABLE_DONTAUDIT);
> > -	if (access(path, F_OK) == 0)
> > +	if (stat(path, &sb) == 0)
> >  		do_rebuild |= !(sepol_get_disable_dontaudit(sh->sepolh) == 1);
> > -	else
> > +	else if (errno == ENOENT) {
> > +		/* The file does not exist */
> >  		do_rebuild |= (sepol_get_disable_dontaudit(sh->sepolh) == 1);
> > +	} else {
> > +		ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
> > +		retval = -1;
> > +		goto cleanup;
> > +	}
> >  	if (sepol_get_disable_dontaudit(sh->sepolh) == 1) {
> >  		FILE *touch;
> >  		touch = fopen(path, "w");
> > @@ -1259,10 +1278,17 @@ static int semanage_direct_commit(semanage_handle_t * sh)
> >  
> >  	/* Create or remove the preserve_tunables flag file. */
> >  	path = semanage_path(SEMANAGE_TMP, SEMANAGE_PRESERVE_TUNABLES);
> > -	if (access(path, F_OK) == 0)
> > +	if (stat(path, &sb) == 0)
> >  		do_rebuild |= !(sepol_get_preserve_tunables(sh->sepolh) == 1);
> > -	else
> > +	else if (errno == ENOENT) {
> > +		/* The file does not exist */
> >  		do_rebuild |= (sepol_get_preserve_tunables(sh->sepolh) == 1);
> > +	} else {
> > +		ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
> > +		retval = -1;
> > +		goto cleanup;
> > +	}
> > +
> >  	if (sepol_get_preserve_tunables(sh->sepolh) == 1) {
> >  		FILE *touch;
> >  		touch = fopen(path, "w");
> > @@ -1299,40 +1325,25 @@ static int semanage_direct_commit(semanage_handle_t * sh)
> >  	 * a rebuild.
> >  	 */
> >  	if (!do_rebuild) {
> > -		path = semanage_path(SEMANAGE_TMP, SEMANAGE_STORE_KERNEL);
> > -		if (access(path, F_OK) != 0) {
> > -			do_rebuild = 1;
> > -			goto rebuild;
> > -		}
> > -
> > -		path = semanage_path(SEMANAGE_TMP, SEMANAGE_STORE_FC);
> > -		if (access(path, F_OK) != 0) {
> > -			do_rebuild = 1;
> > -			goto rebuild;
> > -		}
> > -
> > -		path = semanage_path(SEMANAGE_TMP, SEMANAGE_STORE_SEUSERS);
> > -		if (access(path, F_OK) != 0) {
> > -			do_rebuild = 1;
> > -			goto rebuild;
> > -		}
> > -
> > -		path = semanage_path(SEMANAGE_TMP, SEMANAGE_LINKED);
> > -		if (access(path, F_OK) != 0) {
> > -			do_rebuild = 1;
> > -			goto rebuild;
> > -		}
> > -
> > -		path = semanage_path(SEMANAGE_TMP, SEMANAGE_SEUSERS_LINKED);
> > -		if (access(path, F_OK) != 0) {
> > -			do_rebuild = 1;
> > -			goto rebuild;
> > -		}
> > +		int files[] = {SEMANAGE_STORE_KERNEL,
> > +					   SEMANAGE_STORE_FC,
> > +					   SEMANAGE_STORE_SEUSERS,
> > +					   SEMANAGE_LINKED,
> > +					   SEMANAGE_SEUSERS_LINKED,
> > +					   SEMANAGE_USERS_EXTRA_LINKED};
> > +
> > +		for (i = 0; i < (int) sizeof(files); i++) {
> > +			path = semanage_path(SEMANAGE_TMP, files[i]);
> > +			if (stat(path, &sb) != 0) {
> > +				if (errno != ENOENT) {
> > +					ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
> > +					retval = -1;
> > +					goto cleanup;
> > +				}
> >  
> > -		path = semanage_path(SEMANAGE_TMP, SEMANAGE_USERS_EXTRA_LINKED);
> > -		if (access(path, F_OK) != 0) {
> > -			do_rebuild = 1;
> > -			goto rebuild;
> > +				do_rebuild = 1;
> > +				goto rebuild;
> > +			}
> >  		}
> >  	}
> >  
> > @@ -1465,7 +1476,7 @@ rebuild:
> >  			goto cleanup;
> >  
> >  		path = semanage_path(SEMANAGE_TMP, SEMANAGE_SEUSERS_LINKED);
> > -		if (access(path, F_OK) == 0) {
> > +		if (stat(path, &sb) == 0) {
> >  			retval = semanage_copy_file(path,
> >  						    semanage_path(SEMANAGE_TMP,
> >  								  SEMANAGE_STORE_SEUSERS),
> > @@ -1473,12 +1484,17 @@ rebuild:
> >  			if (retval < 0)
> >  				goto cleanup;
> >  			pseusers->dtable->drop_cache(pseusers->dbase);
> > -		} else {
> > +		} else if (errno == ENOENT) {
> > +			/* The file does not exist */
> >  			pseusers->dtable->clear(sh, pseusers->dbase);
> > +		} else {
> > +			ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
> > +			retval = -1;
> > +			goto cleanup;
> >  		}
> >  
> >  		path = semanage_path(SEMANAGE_TMP, SEMANAGE_USERS_EXTRA_LINKED);
> > -		if (access(path, F_OK) == 0) {
> > +		if (stat(path, &sb) == 0) {
> >  			retval = semanage_copy_file(path,
> >  						    semanage_path(SEMANAGE_TMP,
> >  								  SEMANAGE_USERS_EXTRA),
> > @@ -1486,8 +1502,13 @@ rebuild:
> >  			if (retval < 0)
> >  				goto cleanup;
> >  			pusers_extra->dtable->drop_cache(pusers_extra->dbase);
> > -		} else {
> > +		} else if (errno == ENOENT) {
> > +			/* The file does not exist */
> >  			pusers_extra->dtable->clear(sh, pusers_extra->dbase);
> > +		} else {
> > +			ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
> > +			retval = -1;
> > +			goto cleanup;
> >  		}
> >  	}
> >  
> > @@ -1817,6 +1838,7 @@ static int semanage_direct_extract(semanage_handle_t * sh,
> >  	ssize_t _data_len;
> >  	char *_data;
> >  	int compressed;
> > +	struct stat sb;
> >  
> >  	/* get path of module */
> >  	rc = semanage_module_get_path(
> > @@ -1829,8 +1851,8 @@ static int semanage_direct_extract(semanage_handle_t * sh,
> >  		goto cleanup;
> >  	}
> >  
> > -	if (access(module_path, F_OK) != 0) {
> > -		ERR(sh, "Module does not exist: %s", module_path);
> > +	if (stat(module_path, &sb) != 0) {
> > +		ERR(sh, "Unable to access %s: %s\n", module_path, strerror(errno));
> >  		rc = -1;
> >  		goto cleanup;
> >  	}
> > @@ -1859,7 +1881,13 @@ static int semanage_direct_extract(semanage_handle_t * sh,
> >  		goto cleanup;
> >  	}
> >  
> > -	if (extract_cil == 1 && strcmp(_modinfo->lang_ext, "cil") && access(input_file, F_OK) != 0) {
> > +	if (extract_cil == 1 && strcmp(_modinfo->lang_ext, "cil") && stat(input_file, &sb) != 0) {
> > +		if (errno != ENOENT) {
> > +			ERR(sh, "Unable to access %s: %s\n", input_file, strerror(errno));
> > +			rc = -1;
> > +			goto cleanup;
> > +		}
> > +
> >  		rc = semanage_compile_module(sh, _modinfo);
> >  		if (rc < 0) {
> >  			goto cleanup;
> > @@ -2004,6 +2032,12 @@ static int semanage_direct_get_enabled(semanage_handle_t *sh,
> >  	}
> >  
> >  	if (stat(path, &sb) < 0) {
> > +		if (errno != ENOENT) {
> > +			ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
> > +			status = -1;
> > +			goto cleanup;
> > +		}
> > +
> >  		*enabled = 1;
> >  	}
> >  	else {
> > @@ -2330,6 +2364,12 @@ static int semanage_direct_get_module_info(semanage_handle_t *sh,
> >  
> >  	/* set enabled/disabled status */
> >  	if (stat(fn, &sb) < 0) {
> > +		if (errno != ENOENT) {
> > +			ERR(sh, "Unable to access %s: %s\n", fn, strerror(errno));
> > +			status = -1;
> > +			goto cleanup;
> > +		}
> > +
> >  		ret = semanage_module_info_set_enabled(sh, *modinfo, 1);
> >  		if (ret != 0) {
> >  			status = -1;
> > @@ -2738,6 +2778,7 @@ static int semanage_direct_install_info(semanage_handle_t *sh,
> >  	int status = 0;
> >  	int ret = 0;
> >  	int type;
> > +	struct stat sb;
> >  
> >  	char path[PATH_MAX];
> >  	mode_t mask = umask(0077);
> > @@ -2838,7 +2879,7 @@ static int semanage_direct_install_info(semanage_handle_t *sh,
> >  			goto cleanup;
> >  		}
> >  
> > -		if (access(path, F_OK) == 0) {
> > +		if (stat(path, &sb) == 0) {
> >  			ret = unlink(path);
> >  			if (ret != 0) {
> >  				ERR(sh, "Error while removing cached CIL file %s: %s", path, strerror(errno));
> > diff --git a/libsemanage/src/semanage_store.c b/libsemanage/src/semanage_store.c
> > index 4bd1d651..14ad99c1 100644
> > --- a/libsemanage/src/semanage_store.c
> > +++ b/libsemanage/src/semanage_store.c
> > @@ -514,6 +514,7 @@ char *semanage_conf_path(void)
> >  {
> >  	char *semanage_conf = NULL;
> >  	int len;
> > +	struct stat sb;
> >  
> >  	len = strlen(semanage_root()) + strlen(selinux_path()) + strlen(SEMANAGE_CONF_FILE);
> >  	semanage_conf = calloc(len + 1, sizeof(char));
> > @@ -522,7 +523,7 @@ char *semanage_conf_path(void)
> >  	snprintf(semanage_conf, len + 1, "%s%s%s", semanage_root(), selinux_path(),
> >  		 SEMANAGE_CONF_FILE);
> >  
> > -	if (access(semanage_conf, R_OK) != 0) {
> > +	if (stat(semanage_conf, &sb) != 0 && errno == ENOENT) {
> >  		snprintf(semanage_conf, len + 1, "%s%s", selinux_path(), SEMANAGE_CONF_FILE);
> >  	}
> >  
> > @@ -1508,8 +1509,14 @@ int semanage_split_fc(semanage_handle_t * sh)
> >  static int sefcontext_compile(semanage_handle_t * sh, const char *path) {
> >  
> >  	int r;
> > +	struct stat sb;
> > +
> > +	if (stat(path, &sb) < 0) {
> > +		if (errno != ENOENT) {
> > +			ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
> > +			return -1;
> > +		}
> >  
> > -	if (access(path, F_OK) != 0) {
> >  		return 0;
> >  	}
> >  
> > 
> 

[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 833 bytes --]

Re: [PATCH] libsemanage: replace access() checks to make setuid programs work

[Petr Lautrbach]

[-- Attachment #1: Type: text/plain, Size: 11775 bytes --]

On Fri, Mar 09, 2018 at 04:39:44PM +0100, Vit Mojzis wrote:
> access() uses real UID instead of effective UID which causes false
> negative checks in setuid programs.
> Replace access() calls (mostly tests for file existence) by stat().
> 
> Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1186431
> 
> Signed-off-by: Vit Mojzis <vmojzis@redhat.com>
> ---
>  libsemanage/src/direct_api.c     | 137 +++++++++++++++++++++++++--------------
>  libsemanage/src/semanage_store.c |  11 +++-
>  2 files changed, 98 insertions(+), 50 deletions(-)
> 
> diff --git a/libsemanage/src/direct_api.c b/libsemanage/src/direct_api.c
> index 92d7517d..439122df 100644
> --- a/libsemanage/src/direct_api.c
> +++ b/libsemanage/src/direct_api.c
> @@ -140,6 +140,7 @@ int semanage_direct_is_managed(semanage_handle_t * sh)
>  int semanage_direct_connect(semanage_handle_t * sh)
>  {
>  	const char *path;
> +	struct stat sb;
>  
>  	if (semanage_check_init(sh, sh->conf->store_root_path))
>  		goto err;
> @@ -302,10 +303,16 @@ int semanage_direct_connect(semanage_handle_t * sh)
>  
>  	/* set the disable dontaudit value */
>  	path = semanage_path(SEMANAGE_ACTIVE, SEMANAGE_DISABLE_DONTAUDIT);
> -	if (access(path, F_OK) == 0)
> +
> +	if (stat(path, &sb) == 0)
>  		sepol_set_disable_dontaudit(sh->sepolh, 1);
> -	else
> +	else if (errno == ENOENT) {
> +		/* The file does not exist */
>  		sepol_set_disable_dontaudit(sh->sepolh, 0);
> +	} else {
> +		ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
> +		goto err;
> +	}
>  
>  	return STATUS_SUCCESS;
>  
> @@ -1139,6 +1146,7 @@ static int semanage_compile_hll_modules(semanage_handle_t *sh,
>  	int status = 0;
>  	int i;
>  	char cil_path[PATH_MAX];
> +	struct stat sb;
>  
>  	assert(sh);
>  	assert(modinfos);
> @@ -1155,9 +1163,13 @@ static int semanage_compile_hll_modules(semanage_handle_t *sh,
>  		}
>  
>  		if (semanage_get_ignore_module_cache(sh) == 0 &&
> -				access(cil_path, F_OK) == 0) {
> +				(status = stat(cil_path, &sb)) == 0) {
>  			continue;
>  		}
> +		if (status != 0 && errno != ENOENT) {
> +			ERR(sh, "Unable to access %s: %s\n", cil_path, strerror(errno));
> +			goto cleanup; //an error in the "stat" call
> +		}
>  
>  		status = semanage_compile_module(sh, &modinfos[i]);
>  		if (status < 0) {
> @@ -1196,6 +1208,7 @@ static int semanage_direct_commit(semanage_handle_t * sh)
>  	struct cil_db *cildb = NULL;
>  	semanage_module_info_t *modinfos = NULL;
>  	mode_t mask = umask(0077);
> +	struct stat sb;
>  
>  	int do_rebuild, do_write_kernel, do_install;
>  	int fcontexts_modified, ports_modified, seusers_modified,
> @@ -1234,10 +1247,16 @@ static int semanage_direct_commit(semanage_handle_t * sh)
>  
>  	/* Create or remove the disable_dontaudit flag file. */
>  	path = semanage_path(SEMANAGE_TMP, SEMANAGE_DISABLE_DONTAUDIT);
> -	if (access(path, F_OK) == 0)
> +	if (stat(path, &sb) == 0)
>  		do_rebuild |= !(sepol_get_disable_dontaudit(sh->sepolh) == 1);
> -	else
> +	else if (errno == ENOENT) {
> +		/* The file does not exist */
>  		do_rebuild |= (sepol_get_disable_dontaudit(sh->sepolh) == 1);
> +	} else {
> +		ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
> +		retval = -1;
> +		goto cleanup;
> +	}
>  	if (sepol_get_disable_dontaudit(sh->sepolh) == 1) {
>  		FILE *touch;
>  		touch = fopen(path, "w");
> @@ -1259,10 +1278,17 @@ static int semanage_direct_commit(semanage_handle_t * sh)
>  
>  	/* Create or remove the preserve_tunables flag file. */
>  	path = semanage_path(SEMANAGE_TMP, SEMANAGE_PRESERVE_TUNABLES);
> -	if (access(path, F_OK) == 0)
> +	if (stat(path, &sb) == 0)
>  		do_rebuild |= !(sepol_get_preserve_tunables(sh->sepolh) == 1);
> -	else
> +	else if (errno == ENOENT) {
> +		/* The file does not exist */
>  		do_rebuild |= (sepol_get_preserve_tunables(sh->sepolh) == 1);
> +	} else {
> +		ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
> +		retval = -1;
> +		goto cleanup;
> +	}
> +
>  	if (sepol_get_preserve_tunables(sh->sepolh) == 1) {
>  		FILE *touch;
>  		touch = fopen(path, "w");
> @@ -1299,40 +1325,25 @@ static int semanage_direct_commit(semanage_handle_t * sh)
>  	 * a rebuild.
>  	 */
>  	if (!do_rebuild) {
> -		path = semanage_path(SEMANAGE_TMP, SEMANAGE_STORE_KERNEL);
> -		if (access(path, F_OK) != 0) {
> -			do_rebuild = 1;
> -			goto rebuild;
> -		}
> -
> -		path = semanage_path(SEMANAGE_TMP, SEMANAGE_STORE_FC);
> -		if (access(path, F_OK) != 0) {
> -			do_rebuild = 1;
> -			goto rebuild;
> -		}
> -
> -		path = semanage_path(SEMANAGE_TMP, SEMANAGE_STORE_SEUSERS);
> -		if (access(path, F_OK) != 0) {
> -			do_rebuild = 1;
> -			goto rebuild;
> -		}
> -
> -		path = semanage_path(SEMANAGE_TMP, SEMANAGE_LINKED);
> -		if (access(path, F_OK) != 0) {
> -			do_rebuild = 1;
> -			goto rebuild;
> -		}
> -
> -		path = semanage_path(SEMANAGE_TMP, SEMANAGE_SEUSERS_LINKED);
> -		if (access(path, F_OK) != 0) {
> -			do_rebuild = 1;
> -			goto rebuild;
> -		}
> +		int files[] = {SEMANAGE_STORE_KERNEL,
> +					   SEMANAGE_STORE_FC,
> +					   SEMANAGE_STORE_SEUSERS,
> +					   SEMANAGE_LINKED,
> +					   SEMANAGE_SEUSERS_LINKED,
> +					   SEMANAGE_USERS_EXTRA_LINKED};
> +
> +		for (i = 0; i < (int) sizeof(files); i++) {

The size of the files needs to be divided by size of int, otherwise it causes segfault:

     # semanage fcontext -m -t httpd_log_t "/var/opt/quest/vas/vasd(/
     [1]    3063 segmentation fault (core dumped)  semanage fcontext -m -t httpd_log_t "/var/opt/quest/vas/vasd(/.*)?"
    
    backtrace:
     #0  0x00007fffe7901f9b in semanage_path (store=store@entry=SEMANAGE_TMP, path_name=3918632424) at semanage_store.c:487
     #1  0x00007fffe78f4be1 in semanage_direct_commit (sh=0x55555840da00) at direct_api.c:1336
     #2  0x00007fffe78f9f71 in semanage_commit (sh=0x55555840da00) at handle.c:428


Something like this should fix it:

#define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0]))

for (i = 0; i < ARRAY_SIZE(files); i++) {
...




> +			path = semanage_path(SEMANAGE_TMP, files[i]);
> +			if (stat(path, &sb) != 0) {
> +				if (errno != ENOENT) {
> +					ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
> +					retval = -1;
> +					goto cleanup;
> +				}
>  
> -		path = semanage_path(SEMANAGE_TMP, SEMANAGE_USERS_EXTRA_LINKED);
> -		if (access(path, F_OK) != 0) {
> -			do_rebuild = 1;
> -			goto rebuild;
> +				do_rebuild = 1;
> +				goto rebuild;
> +			}
>  		}
>  	}
>  
> @@ -1465,7 +1476,7 @@ rebuild:
>  			goto cleanup;
>  
>  		path = semanage_path(SEMANAGE_TMP, SEMANAGE_SEUSERS_LINKED);
> -		if (access(path, F_OK) == 0) {
> +		if (stat(path, &sb) == 0) {
>  			retval = semanage_copy_file(path,
>  						    semanage_path(SEMANAGE_TMP,
>  								  SEMANAGE_STORE_SEUSERS),
> @@ -1473,12 +1484,17 @@ rebuild:
>  			if (retval < 0)
>  				goto cleanup;
>  			pseusers->dtable->drop_cache(pseusers->dbase);
> -		} else {
> +		} else if (errno == ENOENT) {
> +			/* The file does not exist */
>  			pseusers->dtable->clear(sh, pseusers->dbase);
> +		} else {
> +			ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
> +			retval = -1;
> +			goto cleanup;
>  		}
>  
>  		path = semanage_path(SEMANAGE_TMP, SEMANAGE_USERS_EXTRA_LINKED);
> -		if (access(path, F_OK) == 0) {
> +		if (stat(path, &sb) == 0) {
>  			retval = semanage_copy_file(path,
>  						    semanage_path(SEMANAGE_TMP,
>  								  SEMANAGE_USERS_EXTRA),
> @@ -1486,8 +1502,13 @@ rebuild:
>  			if (retval < 0)
>  				goto cleanup;
>  			pusers_extra->dtable->drop_cache(pusers_extra->dbase);
> -		} else {
> +		} else if (errno == ENOENT) {
> +			/* The file does not exist */
>  			pusers_extra->dtable->clear(sh, pusers_extra->dbase);
> +		} else {
> +			ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
> +			retval = -1;
> +			goto cleanup;
>  		}
>  	}
>  
> @@ -1817,6 +1838,7 @@ static int semanage_direct_extract(semanage_handle_t * sh,
>  	ssize_t _data_len;
>  	char *_data;
>  	int compressed;
> +	struct stat sb;
>  
>  	/* get path of module */
>  	rc = semanage_module_get_path(
> @@ -1829,8 +1851,8 @@ static int semanage_direct_extract(semanage_handle_t * sh,
>  		goto cleanup;
>  	}
>  
> -	if (access(module_path, F_OK) != 0) {
> -		ERR(sh, "Module does not exist: %s", module_path);
> +	if (stat(module_path, &sb) != 0) {
> +		ERR(sh, "Unable to access %s: %s\n", module_path, strerror(errno));
>  		rc = -1;
>  		goto cleanup;
>  	}
> @@ -1859,7 +1881,13 @@ static int semanage_direct_extract(semanage_handle_t * sh,
>  		goto cleanup;
>  	}
>  
> -	if (extract_cil == 1 && strcmp(_modinfo->lang_ext, "cil") && access(input_file, F_OK) != 0) {
> +	if (extract_cil == 1 && strcmp(_modinfo->lang_ext, "cil") && stat(input_file, &sb) != 0) {
> +		if (errno != ENOENT) {
> +			ERR(sh, "Unable to access %s: %s\n", input_file, strerror(errno));
> +			rc = -1;
> +			goto cleanup;
> +		}
> +
>  		rc = semanage_compile_module(sh, _modinfo);
>  		if (rc < 0) {
>  			goto cleanup;
> @@ -2004,6 +2032,12 @@ static int semanage_direct_get_enabled(semanage_handle_t *sh,
>  	}
>  
>  	if (stat(path, &sb) < 0) {
> +		if (errno != ENOENT) {
> +			ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
> +			status = -1;
> +			goto cleanup;
> +		}
> +
>  		*enabled = 1;
>  	}
>  	else {
> @@ -2330,6 +2364,12 @@ static int semanage_direct_get_module_info(semanage_handle_t *sh,
>  
>  	/* set enabled/disabled status */
>  	if (stat(fn, &sb) < 0) {
> +		if (errno != ENOENT) {
> +			ERR(sh, "Unable to access %s: %s\n", fn, strerror(errno));
> +			status = -1;
> +			goto cleanup;
> +		}
> +
>  		ret = semanage_module_info_set_enabled(sh, *modinfo, 1);
>  		if (ret != 0) {
>  			status = -1;
> @@ -2738,6 +2778,7 @@ static int semanage_direct_install_info(semanage_handle_t *sh,
>  	int status = 0;
>  	int ret = 0;
>  	int type;
> +	struct stat sb;
>  
>  	char path[PATH_MAX];
>  	mode_t mask = umask(0077);
> @@ -2838,7 +2879,7 @@ static int semanage_direct_install_info(semanage_handle_t *sh,
>  			goto cleanup;
>  		}
>  
> -		if (access(path, F_OK) == 0) {
> +		if (stat(path, &sb) == 0) {
>  			ret = unlink(path);
>  			if (ret != 0) {
>  				ERR(sh, "Error while removing cached CIL file %s: %s", path, strerror(errno));
> diff --git a/libsemanage/src/semanage_store.c b/libsemanage/src/semanage_store.c
> index 4bd1d651..14ad99c1 100644
> --- a/libsemanage/src/semanage_store.c
> +++ b/libsemanage/src/semanage_store.c
> @@ -514,6 +514,7 @@ char *semanage_conf_path(void)
>  {
>  	char *semanage_conf = NULL;
>  	int len;
> +	struct stat sb;
>  
>  	len = strlen(semanage_root()) + strlen(selinux_path()) + strlen(SEMANAGE_CONF_FILE);
>  	semanage_conf = calloc(len + 1, sizeof(char));
> @@ -522,7 +523,7 @@ char *semanage_conf_path(void)
>  	snprintf(semanage_conf, len + 1, "%s%s%s", semanage_root(), selinux_path(),
>  		 SEMANAGE_CONF_FILE);
>  
> -	if (access(semanage_conf, R_OK) != 0) {
> +	if (stat(semanage_conf, &sb) != 0 && errno == ENOENT) {
>  		snprintf(semanage_conf, len + 1, "%s%s", selinux_path(), SEMANAGE_CONF_FILE);
>  	}
>  
> @@ -1508,8 +1509,14 @@ int semanage_split_fc(semanage_handle_t * sh)
>  static int sefcontext_compile(semanage_handle_t * sh, const char *path) {
>  
>  	int r;
> +	struct stat sb;
> +
> +	if (stat(path, &sb) < 0) {
> +		if (errno != ENOENT) {
> +			ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
> +			return -1;
> +		}
>  
> -	if (access(path, F_OK) != 0) {
>  		return 0;
>  	}
>  
> -- 
> 2.14.3
> 
> 

[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 833 bytes --]

[PATCH] libsemanage/direct_api.c: Fix iterating over array

[Vit Mojzis]

Fix sizeof calculation in array iteration introduced by commit
6bb8282c4cf66e93daa9684dbe9c75bb6b1e09a7
"libsemanage: replace access() checks to make setuid programs work"

Signed-off-by: Vit Mojzis <vmojzis@redhat.com>
---
 libsemanage/src/direct_api.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/libsemanage/src/direct_api.c b/libsemanage/src/direct_api.c
index 439122df..e7ec952f 100644
--- a/libsemanage/src/direct_api.c
+++ b/libsemanage/src/direct_api.c
@@ -60,6 +60,7 @@
 
 #define PIPE_READ 0
 #define PIPE_WRITE 1
+#define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0]))
 
 static void semanage_direct_destroy(semanage_handle_t * sh);
 static int semanage_direct_disconnect(semanage_handle_t * sh);
@@ -1332,7 +1333,7 @@ static int semanage_direct_commit(semanage_handle_t * sh)
 					   SEMANAGE_SEUSERS_LINKED,
 					   SEMANAGE_USERS_EXTRA_LINKED};
 
-		for (i = 0; i < (int) sizeof(files); i++) {
+		for (i = 0; i < (int) ARRAY_SIZE(files); i++) {
 			path = semanage_path(SEMANAGE_TMP, files[i]);
 			if (stat(path, &sb) != 0) {
 				if (errno != ENOENT) {
-- 
2.14.3

Re: [PATCH] libsemanage/direct_api.c: Fix iterating over array

[William Roberts]

On Mon, Mar 19, 2018 at 7:46 AM, Vit Mojzis <vmojzis@redhat.com> wrote:
> Fix sizeof calculation in array iteration introduced by commit
> 6bb8282c4cf66e93daa9684dbe9c75bb6b1e09a7
> "libsemanage: replace access() checks to make setuid programs work"
>
> Signed-off-by: Vit Mojzis <vmojzis@redhat.com>
> ---
>  libsemanage/src/direct_api.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/libsemanage/src/direct_api.c b/libsemanage/src/direct_api.c
> index 439122df..e7ec952f 100644
> --- a/libsemanage/src/direct_api.c
> +++ b/libsemanage/src/direct_api.c
> @@ -60,6 +60,7 @@
>
>  #define PIPE_READ 0
>  #define PIPE_WRITE 1
> +#define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0]))
>
>  static void semanage_direct_destroy(semanage_handle_t * sh);
>  static int semanage_direct_disconnect(semanage_handle_t * sh);
> @@ -1332,7 +1333,7 @@ static int semanage_direct_commit(semanage_handle_t * sh)
>                                            SEMANAGE_SEUSERS_LINKED,
>                                            SEMANAGE_USERS_EXTRA_LINKED};
>
> -               for (i = 0; i < (int) sizeof(files); i++) {
> +               for (i = 0; i < (int) ARRAY_SIZE(files); i++) {
>                         path = semanage_path(SEMANAGE_TMP, files[i]);
>                         if (stat(path, &sb) != 0) {
>                                 if (errno != ENOENT) {
> --
> 2.14.3
>
>
ack

Just noticing: that code has i as an int, which it probably should be size_t and
the files array as an array of int's, it should probably use the
enum type.

Re: [PATCH] libsemanage/direct_api.c: Fix iterating over array

[William Roberts]

On Mon, Mar 19, 2018 at 8:19 AM, William Roberts
<bill.c.roberts@gmail.com> wrote:
> On Mon, Mar 19, 2018 at 7:46 AM, Vit Mojzis <vmojzis@redhat.com> wrote:
>> Fix sizeof calculation in array iteration introduced by commit
>> 6bb8282c4cf66e93daa9684dbe9c75bb6b1e09a7
>> "libsemanage: replace access() checks to make setuid programs work"
>>
>> Signed-off-by: Vit Mojzis <vmojzis@redhat.com>
>> ---
>>  libsemanage/src/direct_api.c | 3 ++-
>>  1 file changed, 2 insertions(+), 1 deletion(-)
>>
>> diff --git a/libsemanage/src/direct_api.c b/libsemanage/src/direct_api.c
>> index 439122df..e7ec952f 100644
>> --- a/libsemanage/src/direct_api.c
>> +++ b/libsemanage/src/direct_api.c
>> @@ -60,6 +60,7 @@
>>
>>  #define PIPE_READ 0
>>  #define PIPE_WRITE 1
>> +#define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0]))
>>
>>  static void semanage_direct_destroy(semanage_handle_t * sh);
>>  static int semanage_direct_disconnect(semanage_handle_t * sh);
>> @@ -1332,7 +1333,7 @@ static int semanage_direct_commit(semanage_handle_t * sh)
>>                                            SEMANAGE_SEUSERS_LINKED,
>>                                            SEMANAGE_USERS_EXTRA_LINKED};
>>
>> -               for (i = 0; i < (int) sizeof(files); i++) {
>> +               for (i = 0; i < (int) ARRAY_SIZE(files); i++) {
>>                         path = semanage_path(SEMANAGE_TMP, files[i]);
>>                         if (stat(path, &sb) != 0) {
>>                                 if (errno != ENOENT) {
>> --
>> 2.14.3
>>
>>
> ack

Thanks, merged:
https://github.com/SELinuxProject/selinux/pull/87

>
> Just noticing: that code has i as an int, which it probably should be size_t and
> the files array as an array of int's, it should probably use the
> enum type.

Re: [PATCH 3/3] libsemanage: replace access(, F_OK) checks to make setuid programs work

[Stephen Smalley]

On Mon, 2017-06-26 at 14:38 +0200, Vit Mojzis wrote:
> access() uses real UID instead of effective UID which causes false
> negative checks in setuid programs.
> Replace access(,F_OK) (i.e. tests for file existence) by stat().
> 
> Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1186431
> 
> Signed-off-by: Vit Mojzis <vmojzis@redhat.com>
> ---
>  libsemanage/src/direct_api.c | 50 +++++++++++++++++++++++++++++-----
> ----------
>  1 file changed, 33 insertions(+), 17 deletions(-)
> 
> diff --git a/libsemanage/src/direct_api.c
> b/libsemanage/src/direct_api.c
> index ed11a7c..3d1c354 100644
> --- a/libsemanage/src/direct_api.c
> +++ b/libsemanage/src/direct_api.c
> @@ -296,10 +296,19 @@ int semanage_direct_connect(semanage_handle_t *
> sh)
>  
>  	/* set the disable dontaudit value */
>  	path = semanage_path(SEMANAGE_ACTIVE,
> SEMANAGE_DISABLE_DONTAUDIT);
> -	if (access(path, F_OK) == 0)
> +
> +	struct stat sb;

Please add a blank line after declarations before code, and move this
up to the beginning of the function.

> +	if (stat(path, &sb) == 0)
>  		sepol_set_disable_dontaudit(sh->sepolh, 1);
> -	else
> -		sepol_set_disable_dontaudit(sh->sepolh, 0);
> +	else{

Please include a space between else and {.

> +		if (errno == ENOENT){

Please include a space between ) and {.

> +			sepol_set_disable_dontaudit(sh->sepolh, 0);
> +		}
> +		else{

This should be } else { on a single line, with space between else and
{.

> +			ERR(sh, "Unable to access disable_dontaudit
> file at %s: %s\n",path , strerror(errno));
> +			goto err;
> +		}
> +	}
>  
>  	return STATUS_SUCCESS;
>  
> @@ -1114,6 +1123,7 @@ static int
> semanage_compile_hll_modules(semanage_handle_t *sh,
>  	int status = 0;
>  	int i;
>  	char cil_path[PATH_MAX];
> +	struct stat sb;
>  
>  	assert(sh);
>  	assert(modinfos);
> @@ -1130,9 +1140,12 @@ static int
> semanage_compile_hll_modules(semanage_handle_t *sh,
>  		}
>  
>  		if (semanage_get_ignore_module_cache(sh) == 0 &&
> -				access(cil_path, F_OK) == 0) {
> +				(status = stat(cil_path, &sb)) == 0)
> {
>  			continue;
>  		}
> +		if (status != 0 && status != ENOENT) {

errno != ENOENT

Also, we should ERR() here since otherwise we won't get any diagnostic
output (in the other error cases, the called function handles this, but
here we have a direct failure in this function).

> +			goto cleanup; //an error in the "stat" call
> +		}
>  
>  		status = semanage_compile_module(sh, &modinfos[i]);
>  		if (status < 0) {
> @@ -1200,7 +1213,8 @@ static int
> semanage_direct_commit(semanage_handle_t * sh)
>  
>  	/* Create or remove the disable_dontaudit flag file. */
>  	path = semanage_path(SEMANAGE_TMP,
> SEMANAGE_DISABLE_DONTAUDIT);
> -	if (access(path, F_OK) == 0)
> +	struct stat sb;

Empty line between declarations and code, move decls to beginning of
function.

> +	if (stat(path, &sb) == 0)
>  		do_rebuild |= !(sepol_get_disable_dontaudit(sh-
> >sepolh) == 1);
>  	else
>  		do_rebuild |= (sepol_get_disable_dontaudit(sh-
> >sepolh) == 1);

No errno check here or below?

> @@ -1225,7 +1239,7 @@ static int
> semanage_direct_commit(semanage_handle_t * sh)
>  
>  	/* Create or remove the preserve_tunables flag file. */
>  	path = semanage_path(SEMANAGE_TMP,
> SEMANAGE_PRESERVE_TUNABLES);
> -	if (access(path, F_OK) == 0)
> +	if (stat(path, &sb) == 0)
>  		do_rebuild |= !(sepol_get_preserve_tunables(sh-
> >sepolh) == 1);
>  	else
>  		do_rebuild |= (sepol_get_preserve_tunables(sh-
> >sepolh) == 1);
> @@ -1266,37 +1280,37 @@ static int
> semanage_direct_commit(semanage_handle_t * sh)
>  	 */
>  	if (!do_rebuild) {
>  		path = semanage_path(SEMANAGE_TMP,
> SEMANAGE_STORE_KERNEL);
> -		if (access(path, F_OK) != 0) {
> +		if (stat(path, &sb) != 0) {
>  			do_rebuild = 1;
>  			goto rebuild;
>  		}
>  
>  		path = semanage_path(SEMANAGE_TMP,
> SEMANAGE_STORE_FC);
> -		if (access(path, F_OK) != 0) {
> +		if (stat(path, &sb) != 0) {
>  			do_rebuild = 1;
>  			goto rebuild;
>  		}
>  
>  		path = semanage_path(SEMANAGE_TMP,
> SEMANAGE_STORE_SEUSERS);
> -		if (access(path, F_OK) != 0) {
> +		if (stat(path, &sb) != 0) {
>  			do_rebuild = 1;
>  			goto rebuild;
>  		}
>  
>  		path = semanage_path(SEMANAGE_TMP, SEMANAGE_LINKED);
> -		if (access(path, F_OK) != 0) {
> +		if (stat(path, &sb) != 0) {
>  			do_rebuild = 1;
>  			goto rebuild;
>  		}
>  
>  		path = semanage_path(SEMANAGE_TMP,
> SEMANAGE_SEUSERS_LINKED);
> -		if (access(path, F_OK) != 0) {
> +		if (stat(path, &sb) != 0) {
>  			do_rebuild = 1;
>  			goto rebuild;
>  		}
>  
>  		path = semanage_path(SEMANAGE_TMP,
> SEMANAGE_USERS_EXTRA_LINKED);
> -		if (access(path, F_OK) != 0) {
> +		if (stat(path, &sb) != 0) {
>  			do_rebuild = 1;
>  			goto rebuild;
>  		}
> @@ -1431,7 +1445,7 @@ rebuild:
>  			goto cleanup;
>  
>  		path = semanage_path(SEMANAGE_TMP,
> SEMANAGE_SEUSERS_LINKED);
> -		if (access(path, F_OK) == 0) {
> +		if (stat(path, &sb) == 0) {
>  			retval = semanage_copy_file(path,
>  						    semanage_path(SE
> MANAGE_TMP,
>  								  SE
> MANAGE_STORE_SEUSERS),
> @@ -1444,7 +1458,7 @@ rebuild:
>  		}
>  
>  		path = semanage_path(SEMANAGE_TMP,
> SEMANAGE_USERS_EXTRA_LINKED);
> -		if (access(path, F_OK) == 0) {
> +		if (stat(path, &sb) == 0) {
>  			retval = semanage_copy_file(path,
>  						    semanage_path(SE
> MANAGE_TMP,
>  								  SE
> MANAGE_USERS_EXTRA),
> @@ -1785,7 +1799,8 @@ static int
> semanage_direct_extract(semanage_handle_t * sh,
>  		goto cleanup;
>  	}
>  
> -	if (access(module_path, F_OK) != 0) {
> +	struct stat sb;
> +	if (stat(module_path, &sb) != 0) {
>  		ERR(sh, "Module does not exist: %s", module_path);
>  		rc = -1;
>  		goto cleanup;
> @@ -1815,7 +1830,7 @@ static int
> semanage_direct_extract(semanage_handle_t * sh,
>  		goto cleanup;
>  	}
>  
> -	if (extract_cil == 1 && strcmp(_modinfo->lang_ext, "cil") &&
> access(input_file, F_OK) != 0) {
> +	if (extract_cil == 1 && strcmp(_modinfo->lang_ext, "cil") &&
> stat(input_file, &sb) != 0) {
>  		rc = semanage_compile_module(sh, _modinfo);
>  		if (rc < 0) {
>  			goto cleanup;
> @@ -2790,7 +2805,8 @@ static int
> semanage_direct_install_info(semanage_handle_t *sh,
>  			goto cleanup;
>  		}
>  
> -		if (access(path, F_OK) == 0) {
> +		struct stat sb;
> +		if (stat(path, &sb) == 0) {
>  			ret = unlink(path);
>  			if (ret != 0) {
>  				ERR(sh, "Error while removing cached
> CIL file %s: %s", path, strerror(errno));

[PATCH 1/3] libsemanage: remove access() check to make setuid programs work

[Vit Mojzis]

access() uses real UID instead of effective UID which causes false
negative checks in setuid programs. Remove redundant access() checks

Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1186431

Signed-off-by: Vit Mojzis <vmojzis@redhat.com>
---
 libsemanage/src/direct_api.c     |  7 -------
 libsemanage/src/semanage_store.c | 17 ++++++++---------
 2 files changed, 8 insertions(+), 16 deletions(-)

diff --git a/libsemanage/src/direct_api.c b/libsemanage/src/direct_api.c
index 88873c43..b7899d68 100644
--- a/libsemanage/src/direct_api.c
+++ b/libsemanage/src/direct_api.c
@@ -148,9 +148,6 @@ int semanage_direct_connect(semanage_handle_t * sh)
 		if (semanage_create_store(sh, 1))
 			goto err;
 
-	if (semanage_access_check(sh) < SEMANAGE_CAN_READ)
-		goto err;
-
 	sh->u.direct.translock_file_fd = -1;
 	sh->u.direct.activelock_file_fd = -1;
 
@@ -398,10 +395,6 @@ static int semanage_direct_disconnect(semanage_handle_t *sh)
 
 static int semanage_direct_begintrans(semanage_handle_t * sh)
 {
-
-	if (semanage_access_check(sh) != SEMANAGE_CAN_WRITE) {
-		return -1;
-	}
 	if (semanage_get_trans_lock(sh) < 0) {
 		return -1;
 	}
diff --git a/libsemanage/src/semanage_store.c b/libsemanage/src/semanage_store.c
index 936e6495..4bd1d651 100644
--- a/libsemanage/src/semanage_store.c
+++ b/libsemanage/src/semanage_store.c
@@ -538,7 +538,6 @@ char *semanage_conf_path(void)
 int semanage_create_store(semanage_handle_t * sh, int create)
 {
 	struct stat sb;
-	int mode_mask = R_OK | W_OK | X_OK;
 	const char *path = semanage_files[SEMANAGE_ROOT];
 	int fd;
 
@@ -557,9 +556,9 @@ int semanage_create_store(semanage_handle_t * sh, int create)
 			return -1;
 		}
 	} else {
-		if (!S_ISDIR(sb.st_mode) || access(path, mode_mask) == -1) {
+		if (!S_ISDIR(sb.st_mode)) {
 			ERR(sh,
-			    "Could not access module store at %s, or it is not a directory.",
+			    "Module store at %s is not a directory.",
 			    path);
 			return -1;
 		}
@@ -580,9 +579,9 @@ int semanage_create_store(semanage_handle_t * sh, int create)
 			return -1;
 		}
 	} else {
-		if (!S_ISDIR(sb.st_mode) || access(path, mode_mask) == -1) {
+		if (!S_ISDIR(sb.st_mode)) {
 			ERR(sh,
-			    "Could not access module store active subdirectory at %s, or it is not a directory.",
+			    "Module store active subdirectory at %s is not a directory.",
 			    path);
 			return -1;
 		}
@@ -603,9 +602,9 @@ int semanage_create_store(semanage_handle_t * sh, int create)
 			return -1;
 		}
 	} else {
-		if (!S_ISDIR(sb.st_mode) || access(path, mode_mask) == -1) {
+		if (!S_ISDIR(sb.st_mode)) {
 			ERR(sh,
-			    "Could not access module store active modules subdirectory at %s, or it is not a directory.",
+			    "Module store active modules subdirectory at %s is not a directory.",
 			    path);
 			return -1;
 		}
@@ -624,8 +623,8 @@ int semanage_create_store(semanage_handle_t * sh, int create)
 			return -1;
 		}
 	} else {
-		if (!S_ISREG(sb.st_mode) || access(path, R_OK | W_OK) == -1) {
-			ERR(sh, "Could not access lock file at %s.", path);
+		if (!S_ISREG(sb.st_mode)) {
+			ERR(sh, "Object at %s is not a lock file.", path);
 			return -1;
 		}
 	}
-- 
2.14.3

[PATCH 3/3] libsemanage: replace access() checks to make setuid programs work

[Vit Mojzis]

access() uses real UID instead of effective UID which causes false
negative checks in setuid programs.
Replace access(,F_OK) (i.e. tests for file existence) by stat().
And access(,R_OK) by fopen(,"r")

Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1186431

Signed-off-by: Vit Mojzis <vmojzis@redhat.com>
---
 libsemanage/src/direct_api.c     | 132 +++++++++++++++++++++++++--------------
 libsemanage/src/semanage_store.c |  14 ++++-
 2 files changed, 98 insertions(+), 48 deletions(-)

diff --git a/libsemanage/src/direct_api.c b/libsemanage/src/direct_api.c
index f4d57cf8..d42a51cd 100644
--- a/libsemanage/src/direct_api.c
+++ b/libsemanage/src/direct_api.c
@@ -140,6 +140,7 @@ int semanage_direct_is_managed(semanage_handle_t * sh)
 int semanage_direct_connect(semanage_handle_t * sh)
 {
 	const char *path;
+	struct stat sb;
 
 	if (semanage_check_init(sh, sh->conf->store_root_path))
 		goto err;
@@ -302,10 +303,17 @@ int semanage_direct_connect(semanage_handle_t * sh)
 
 	/* set the disable dontaudit value */
 	path = semanage_path(SEMANAGE_ACTIVE, SEMANAGE_DISABLE_DONTAUDIT);
-	if (access(path, F_OK) == 0)
+
+	if (stat(path, &sb) == 0)
 		sepol_set_disable_dontaudit(sh->sepolh, 1);
-	else
+	else {
+		if (errno != ENOENT) {
+			ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
+			goto err;
+		}
+
 		sepol_set_disable_dontaudit(sh->sepolh, 0);
+	}
 
 	return STATUS_SUCCESS;
 
@@ -1139,6 +1147,7 @@ static int semanage_compile_hll_modules(semanage_handle_t *sh,
 	int status = 0;
 	int i;
 	char cil_path[PATH_MAX];
+	struct stat sb;
 
 	assert(sh);
 	assert(modinfos);
@@ -1155,9 +1164,13 @@ static int semanage_compile_hll_modules(semanage_handle_t *sh,
 		}
 
 		if (semanage_get_ignore_module_cache(sh) == 0 &&
-				access(cil_path, F_OK) == 0) {
+				(status = stat(cil_path, &sb)) == 0) {
 			continue;
 		}
+		if (status != 0 && errno != ENOENT) {
+			ERR(sh, "Unable to access %s: %s\n", cil_path, strerror(errno));
+			goto cleanup; //an error in the "stat" call
+		}
 
 		status = semanage_compile_module(sh, &modinfos[i]);
 		if (status < 0) {
@@ -1188,6 +1201,7 @@ static int semanage_direct_commit(semanage_handle_t * sh)
 	struct cil_db *cildb = NULL;
 	semanage_module_info_t *modinfos = NULL;
 	mode_t mask = umask(0077);
+	struct stat sb;
 
 	int do_rebuild, do_write_kernel, do_install;
 	int fcontexts_modified, ports_modified, seusers_modified,
@@ -1226,10 +1240,16 @@ static int semanage_direct_commit(semanage_handle_t * sh)
 
 	/* Create or remove the disable_dontaudit flag file. */
 	path = semanage_path(SEMANAGE_TMP, SEMANAGE_DISABLE_DONTAUDIT);
-	if (access(path, F_OK) == 0)
+	if (stat(path, &sb) == 0)
 		do_rebuild |= !(sepol_get_disable_dontaudit(sh->sepolh) == 1);
-	else
+	else {
+		if (errno != ENOENT) {
+			ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
+			goto cleanup;
+		}
+
 		do_rebuild |= (sepol_get_disable_dontaudit(sh->sepolh) == 1);
+	}
 	if (sepol_get_disable_dontaudit(sh->sepolh) == 1) {
 		FILE *touch;
 		touch = fopen(path, "w");
@@ -1251,10 +1271,17 @@ static int semanage_direct_commit(semanage_handle_t * sh)
 
 	/* Create or remove the preserve_tunables flag file. */
 	path = semanage_path(SEMANAGE_TMP, SEMANAGE_PRESERVE_TUNABLES);
-	if (access(path, F_OK) == 0)
+	if (stat(path, &sb) == 0)
 		do_rebuild |= !(sepol_get_preserve_tunables(sh->sepolh) == 1);
-	else
+	else {
+		if (errno != ENOENT) {
+			ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
+			goto cleanup;
+		}
+
 		do_rebuild |= (sepol_get_preserve_tunables(sh->sepolh) == 1);
+	}
+
 	if (sepol_get_preserve_tunables(sh->sepolh) == 1) {
 		FILE *touch;
 		touch = fopen(path, "w");
@@ -1291,40 +1318,24 @@ static int semanage_direct_commit(semanage_handle_t * sh)
 	 * a rebuild.
 	 */
 	if (!do_rebuild) {
-		path = semanage_path(SEMANAGE_TMP, SEMANAGE_STORE_KERNEL);
-		if (access(path, F_OK) != 0) {
-			do_rebuild = 1;
-			goto rebuild;
-		}
-
-		path = semanage_path(SEMANAGE_TMP, SEMANAGE_STORE_FC);
-		if (access(path, F_OK) != 0) {
-			do_rebuild = 1;
-			goto rebuild;
-		}
-
-		path = semanage_path(SEMANAGE_TMP, SEMANAGE_STORE_SEUSERS);
-		if (access(path, F_OK) != 0) {
-			do_rebuild = 1;
-			goto rebuild;
-		}
-
-		path = semanage_path(SEMANAGE_TMP, SEMANAGE_LINKED);
-		if (access(path, F_OK) != 0) {
-			do_rebuild = 1;
-			goto rebuild;
-		}
-
-		path = semanage_path(SEMANAGE_TMP, SEMANAGE_SEUSERS_LINKED);
-		if (access(path, F_OK) != 0) {
-			do_rebuild = 1;
-			goto rebuild;
-		}
+		int files[] = {SEMANAGE_STORE_KERNEL,
+					   SEMANAGE_STORE_FC,
+					   SEMANAGE_STORE_SEUSERS,
+					   SEMANAGE_LINKED,
+					   SEMANAGE_SEUSERS_LINKED,
+					   SEMANAGE_USERS_EXTRA_LINKED};
+
+		for (i = 0; i < (int) sizeof(files); i++) {
+			path = semanage_path(SEMANAGE_TMP, files[i]);
+			if (stat(path, &sb) != 0) {
+				if (errno != ENOENT) {
+					ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
+					goto cleanup;
+				}
 
-		path = semanage_path(SEMANAGE_TMP, SEMANAGE_USERS_EXTRA_LINKED);
-		if (access(path, F_OK) != 0) {
-			do_rebuild = 1;
-			goto rebuild;
+				do_rebuild = 1;
+				goto rebuild;
+			}
 		}
 	}
 
@@ -1457,7 +1468,7 @@ rebuild:
 			goto cleanup;
 
 		path = semanage_path(SEMANAGE_TMP, SEMANAGE_SEUSERS_LINKED);
-		if (access(path, F_OK) == 0) {
+		if (stat(path, &sb) == 0) {
 			retval = semanage_copy_file(path,
 						    semanage_path(SEMANAGE_TMP,
 								  SEMANAGE_STORE_SEUSERS),
@@ -1466,11 +1477,16 @@ rebuild:
 				goto cleanup;
 			pseusers->dtable->drop_cache(pseusers->dbase);
 		} else {
+			if (errno != ENOENT) {
+				ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
+				goto cleanup;
+			}
+
 			pseusers->dtable->clear(sh, pseusers->dbase);
 		}
 
 		path = semanage_path(SEMANAGE_TMP, SEMANAGE_USERS_EXTRA_LINKED);
-		if (access(path, F_OK) == 0) {
+		if (stat(path, &sb) == 0) {
 			retval = semanage_copy_file(path,
 						    semanage_path(SEMANAGE_TMP,
 								  SEMANAGE_USERS_EXTRA),
@@ -1479,6 +1495,11 @@ rebuild:
 				goto cleanup;
 			pusers_extra->dtable->drop_cache(pusers_extra->dbase);
 		} else {
+			if (errno != ENOENT) {
+				ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
+				goto cleanup;
+			}
+
 			pusers_extra->dtable->clear(sh, pusers_extra->dbase);
 		}
 	}
@@ -1809,6 +1830,7 @@ static int semanage_direct_extract(semanage_handle_t * sh,
 	ssize_t _data_len;
 	char *_data;
 	int compressed;
+	struct stat sb;
 
 	/* get path of module */
 	rc = semanage_module_get_path(
@@ -1821,8 +1843,8 @@ static int semanage_direct_extract(semanage_handle_t * sh,
 		goto cleanup;
 	}
 
-	if (access(module_path, F_OK) != 0) {
-		ERR(sh, "Module does not exist: %s", module_path);
+	if (stat(module_path, &sb) != 0) {
+		ERR(sh, "Unable to access %s: %s\n", module_path, strerror(errno));
 		rc = -1;
 		goto cleanup;
 	}
@@ -1851,7 +1873,12 @@ static int semanage_direct_extract(semanage_handle_t * sh,
 		goto cleanup;
 	}
 
-	if (extract_cil == 1 && strcmp(_modinfo->lang_ext, "cil") && access(input_file, F_OK) != 0) {
+	if (extract_cil == 1 && strcmp(_modinfo->lang_ext, "cil") && stat(input_file, &sb) != 0) {
+		if (errno != ENOENT) {
+			ERR(sh, "Unable to access %s: %s\n", input_file, strerror(errno));
+			goto cleanup;
+		}
+
 		rc = semanage_compile_module(sh, _modinfo);
 		if (rc < 0) {
 			goto cleanup;
@@ -1996,6 +2023,12 @@ static int semanage_direct_get_enabled(semanage_handle_t *sh,
 	}
 
 	if (stat(path, &sb) < 0) {
+		if (errno != ENOENT) {
+			ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
+			status = -1;
+			goto cleanup;
+		}
+
 		*enabled = 1;
 	}
 	else {
@@ -2322,6 +2355,12 @@ static int semanage_direct_get_module_info(semanage_handle_t *sh,
 
 	/* set enabled/disabled status */
 	if (stat(fn, &sb) < 0) {
+		if (errno != ENOENT) {
+			ERR(sh, "Unable to access %s: %s\n", fn, strerror(errno));
+			status = -1;
+			goto cleanup;
+		}
+
 		ret = semanage_module_info_set_enabled(sh, *modinfo, 1);
 		if (ret != 0) {
 			status = -1;
@@ -2730,6 +2769,7 @@ static int semanage_direct_install_info(semanage_handle_t *sh,
 	int status = 0;
 	int ret = 0;
 	int type;
+	struct stat sb;
 
 	char path[PATH_MAX];
 	mode_t mask = umask(0077);
@@ -2830,7 +2870,7 @@ static int semanage_direct_install_info(semanage_handle_t *sh,
 			goto cleanup;
 		}
 
-		if (access(path, F_OK) == 0) {
+		if (stat(path, &sb) == 0) {
 			ret = unlink(path);
 			if (ret != 0) {
 				ERR(sh, "Error while removing cached CIL file %s: %s", path, strerror(errno));
diff --git a/libsemanage/src/semanage_store.c b/libsemanage/src/semanage_store.c
index 4bd1d651..83c188dc 100644
--- a/libsemanage/src/semanage_store.c
+++ b/libsemanage/src/semanage_store.c
@@ -514,6 +514,7 @@ char *semanage_conf_path(void)
 {
 	char *semanage_conf = NULL;
 	int len;
+	FILE *fp = NULL;
 
 	len = strlen(semanage_root()) + strlen(selinux_path()) + strlen(SEMANAGE_CONF_FILE);
 	semanage_conf = calloc(len + 1, sizeof(char));
@@ -522,7 +523,10 @@ char *semanage_conf_path(void)
 	snprintf(semanage_conf, len + 1, "%s%s%s", semanage_root(), selinux_path(),
 		 SEMANAGE_CONF_FILE);
 
-	if (access(semanage_conf, R_OK) != 0) {
+	//the following replaces access(semanage_conf, R_OK) check
+	if ((fp = fopen(semanage_conf, "r")) != NULL) {
+		fclose(fp);
+	} else {
 		snprintf(semanage_conf, len + 1, "%s%s", selinux_path(), SEMANAGE_CONF_FILE);
 	}
 
@@ -1508,8 +1512,14 @@ int semanage_split_fc(semanage_handle_t * sh)
 static int sefcontext_compile(semanage_handle_t * sh, const char *path) {
 
 	int r;
+	struct stat sb;
+
+	if (stat(path, &sb) < 0) {
+		if (errno != ENOENT) {
+			ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
+			return -1;
+		}
 
-	if (access(path, F_OK) != 0) {
 		return 0;
 	}
 
-- 
2.14.3

Re: [PATCH 3/3] libsemanage: replace access() checks to make setuid programs work

[William Roberts]

On Wed, Feb 28, 2018 at 2:15 AM, Vit Mojzis <vmojzis@redhat.com> wrote:
> access() uses real UID instead of effective UID which causes false
> negative checks in setuid programs.
> Replace access(,F_OK) (i.e. tests for file existence) by stat().
> And access(,R_OK) by fopen(,"r")
>
> Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1186431
>
> Signed-off-by: Vit Mojzis <vmojzis@redhat.com>
> ---
>  libsemanage/src/direct_api.c     | 132 +++++++++++++++++++++++++--------------
>  libsemanage/src/semanage_store.c |  14 ++++-
>  2 files changed, 98 insertions(+), 48 deletions(-)
>
> diff --git a/libsemanage/src/direct_api.c b/libsemanage/src/direct_api.c
> index f4d57cf8..d42a51cd 100644
> --- a/libsemanage/src/direct_api.c
> +++ b/libsemanage/src/direct_api.c
> @@ -140,6 +140,7 @@ int semanage_direct_is_managed(semanage_handle_t * sh)
>  int semanage_direct_connect(semanage_handle_t * sh)
>  {
>         const char *path;
> +       struct stat sb;
>
>         if (semanage_check_init(sh, sh->conf->store_root_path))
>                 goto err;
> @@ -302,10 +303,17 @@ int semanage_direct_connect(semanage_handle_t * sh)
>
>         /* set the disable dontaudit value */
>         path = semanage_path(SEMANAGE_ACTIVE, SEMANAGE_DISABLE_DONTAUDIT);
> -       if (access(path, F_OK) == 0)
> +
> +       if (stat(path, &sb) == 0)
>                 sepol_set_disable_dontaudit(sh->sepolh, 1);
> -       else
> +       else {
> +               if (errno != ENOENT) {
> +                       ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
> +                       goto err;
> +               }
> +
>                 sepol_set_disable_dontaudit(sh->sepolh, 0);
> +       }
>
>         return STATUS_SUCCESS;
>
> @@ -1139,6 +1147,7 @@ static int semanage_compile_hll_modules(semanage_handle_t *sh,
>         int status = 0;
>         int i;
>         char cil_path[PATH_MAX];
> +       struct stat sb;
>
>         assert(sh);
>         assert(modinfos);
> @@ -1155,9 +1164,13 @@ static int semanage_compile_hll_modules(semanage_handle_t *sh,
>                 }
>
>                 if (semanage_get_ignore_module_cache(sh) == 0 &&
> -                               access(cil_path, F_OK) == 0) {
> +                               (status = stat(cil_path, &sb)) == 0) {
>                         continue;
>                 }
> +               if (status != 0 && errno != ENOENT) {
> +                       ERR(sh, "Unable to access %s: %s\n", cil_path, strerror(errno));
> +                       goto cleanup; //an error in the "stat" call
> +               }
>
>                 status = semanage_compile_module(sh, &modinfos[i]);
>                 if (status < 0) {
> @@ -1188,6 +1201,7 @@ static int semanage_direct_commit(semanage_handle_t * sh)
>         struct cil_db *cildb = NULL;
>         semanage_module_info_t *modinfos = NULL;
>         mode_t mask = umask(0077);
> +       struct stat sb;
>
>         int do_rebuild, do_write_kernel, do_install;
>         int fcontexts_modified, ports_modified, seusers_modified,
> @@ -1226,10 +1240,16 @@ static int semanage_direct_commit(semanage_handle_t * sh)
>
>         /* Create or remove the disable_dontaudit flag file. */
>         path = semanage_path(SEMANAGE_TMP, SEMANAGE_DISABLE_DONTAUDIT);
> -       if (access(path, F_OK) == 0)
> +       if (stat(path, &sb) == 0)
>                 do_rebuild |= !(sepol_get_disable_dontaudit(sh->sepolh) == 1);
> -       else
> +       else {
> +               if (errno != ENOENT) {
> +                       ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
> +                       goto cleanup;
> +               }
> +

I am not a huge fan of this if under else block of if (errno !=ENOENT).

maybe this is a bit cleaner:

if (stat() == 0)
  //exists
else if (errno == ENOENT)
  // doesn't exist
else
  //fail

>                 do_rebuild |= (sepol_get_disable_dontaudit(sh->sepolh) == 1);
> +       }
>         if (sepol_get_disable_dontaudit(sh->sepolh) == 1) {
>                 FILE *touch;
>                 touch = fopen(path, "w");
> @@ -1251,10 +1271,17 @@ static int semanage_direct_commit(semanage_handle_t * sh)
>
>         /* Create or remove the preserve_tunables flag file. */
>         path = semanage_path(SEMANAGE_TMP, SEMANAGE_PRESERVE_TUNABLES);
> -       if (access(path, F_OK) == 0)
> +       if (stat(path, &sb) == 0)
>                 do_rebuild |= !(sepol_get_preserve_tunables(sh->sepolh) == 1);
> -       else
> +       else {
> +               if (errno != ENOENT) {
> +                       ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
> +                       goto cleanup;
> +               }
> +
>                 do_rebuild |= (sepol_get_preserve_tunables(sh->sepolh) == 1);
> +       }
> +
>         if (sepol_get_preserve_tunables(sh->sepolh) == 1) {
>                 FILE *touch;
>                 touch = fopen(path, "w");
> @@ -1291,40 +1318,24 @@ static int semanage_direct_commit(semanage_handle_t * sh)
>          * a rebuild.
>          */
>         if (!do_rebuild) {
> -               path = semanage_path(SEMANAGE_TMP, SEMANAGE_STORE_KERNEL);
> -               if (access(path, F_OK) != 0) {
> -                       do_rebuild = 1;
> -                       goto rebuild;
> -               }
> -
> -               path = semanage_path(SEMANAGE_TMP, SEMANAGE_STORE_FC);
> -               if (access(path, F_OK) != 0) {
> -                       do_rebuild = 1;
> -                       goto rebuild;
> -               }
> -
> -               path = semanage_path(SEMANAGE_TMP, SEMANAGE_STORE_SEUSERS);
> -               if (access(path, F_OK) != 0) {
> -                       do_rebuild = 1;
> -                       goto rebuild;
> -               }
> -
> -               path = semanage_path(SEMANAGE_TMP, SEMANAGE_LINKED);
> -               if (access(path, F_OK) != 0) {
> -                       do_rebuild = 1;
> -                       goto rebuild;
> -               }
> -
> -               path = semanage_path(SEMANAGE_TMP, SEMANAGE_SEUSERS_LINKED);
> -               if (access(path, F_OK) != 0) {
> -                       do_rebuild = 1;
> -                       goto rebuild;
> -               }
> +               int files[] = {SEMANAGE_STORE_KERNEL,
> +                                          SEMANAGE_STORE_FC,
> +                                          SEMANAGE_STORE_SEUSERS,
> +                                          SEMANAGE_LINKED,
> +                                          SEMANAGE_SEUSERS_LINKED,
> +                                          SEMANAGE_USERS_EXTRA_LINKED};
> +
> +               for (i = 0; i < (int) sizeof(files); i++) {
> +                       path = semanage_path(SEMANAGE_TMP, files[i]);
> +                       if (stat(path, &sb) != 0) {
> +                               if (errno != ENOENT) {
> +                                       ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
> +                                       goto cleanup;
> +                               }
>
> -               path = semanage_path(SEMANAGE_TMP, SEMANAGE_USERS_EXTRA_LINKED);
> -               if (access(path, F_OK) != 0) {
> -                       do_rebuild = 1;
> -                       goto rebuild;
> +                               do_rebuild = 1;
> +                               goto rebuild;
> +                       }
>                 }
>         }
>
> @@ -1457,7 +1468,7 @@ rebuild:
>                         goto cleanup;
>
>                 path = semanage_path(SEMANAGE_TMP, SEMANAGE_SEUSERS_LINKED);
> -               if (access(path, F_OK) == 0) {
> +               if (stat(path, &sb) == 0) {
>                         retval = semanage_copy_file(path,
>                                                     semanage_path(SEMANAGE_TMP,
>                                                                   SEMANAGE_STORE_SEUSERS),
> @@ -1466,11 +1477,16 @@ rebuild:
>                                 goto cleanup;
>                         pseusers->dtable->drop_cache(pseusers->dbase);
>                 } else {
> +                       if (errno != ENOENT) {
> +                               ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
> +                               goto cleanup;
> +                       }
> +
>                         pseusers->dtable->clear(sh, pseusers->dbase);
>                 }
>
>                 path = semanage_path(SEMANAGE_TMP, SEMANAGE_USERS_EXTRA_LINKED);
> -               if (access(path, F_OK) == 0) {
> +               if (stat(path, &sb) == 0) {
>                         retval = semanage_copy_file(path,
>                                                     semanage_path(SEMANAGE_TMP,
>                                                                   SEMANAGE_USERS_EXTRA),
> @@ -1479,6 +1495,11 @@ rebuild:
>                                 goto cleanup;
>                         pusers_extra->dtable->drop_cache(pusers_extra->dbase);
>                 } else {
> +                       if (errno != ENOENT) {
> +                               ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
> +                               goto cleanup;
> +                       }
> +
>                         pusers_extra->dtable->clear(sh, pusers_extra->dbase);
>                 }
>         }
> @@ -1809,6 +1830,7 @@ static int semanage_direct_extract(semanage_handle_t * sh,
>         ssize_t _data_len;
>         char *_data;
>         int compressed;
> +       struct stat sb;
>
>         /* get path of module */
>         rc = semanage_module_get_path(
> @@ -1821,8 +1843,8 @@ static int semanage_direct_extract(semanage_handle_t * sh,
>                 goto cleanup;
>         }
>
> -       if (access(module_path, F_OK) != 0) {
> -               ERR(sh, "Module does not exist: %s", module_path);
> +       if (stat(module_path, &sb) != 0) {
> +               ERR(sh, "Unable to access %s: %s\n", module_path, strerror(errno));
>                 rc = -1;
>                 goto cleanup;
>         }
> @@ -1851,7 +1873,12 @@ static int semanage_direct_extract(semanage_handle_t * sh,
>                 goto cleanup;
>         }
>
> -       if (extract_cil == 1 && strcmp(_modinfo->lang_ext, "cil") && access(input_file, F_OK) != 0) {
> +       if (extract_cil == 1 && strcmp(_modinfo->lang_ext, "cil") && stat(input_file, &sb) != 0) {
> +               if (errno != ENOENT) {
> +                       ERR(sh, "Unable to access %s: %s\n", input_file, strerror(errno));
> +                       goto cleanup;
> +               }
> +
>                 rc = semanage_compile_module(sh, _modinfo);
>                 if (rc < 0) {
>                         goto cleanup;
> @@ -1996,6 +2023,12 @@ static int semanage_direct_get_enabled(semanage_handle_t *sh,
>         }
>
>         if (stat(path, &sb) < 0) {
> +               if (errno != ENOENT) {
> +                       ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
> +                       status = -1;
> +                       goto cleanup;
> +               }
> +
>                 *enabled = 1;
>         }
>         else {
> @@ -2322,6 +2355,12 @@ static int semanage_direct_get_module_info(semanage_handle_t *sh,
>
>         /* set enabled/disabled status */
>         if (stat(fn, &sb) < 0) {
> +               if (errno != ENOENT) {
> +                       ERR(sh, "Unable to access %s: %s\n", fn, strerror(errno));
> +                       status = -1;
> +                       goto cleanup;
> +               }
> +
>                 ret = semanage_module_info_set_enabled(sh, *modinfo, 1);
>                 if (ret != 0) {
>                         status = -1;
> @@ -2730,6 +2769,7 @@ static int semanage_direct_install_info(semanage_handle_t *sh,
>         int status = 0;
>         int ret = 0;
>         int type;
> +       struct stat sb;
>
>         char path[PATH_MAX];
>         mode_t mask = umask(0077);
> @@ -2830,7 +2870,7 @@ static int semanage_direct_install_info(semanage_handle_t *sh,
>                         goto cleanup;
>                 }
>
> -               if (access(path, F_OK) == 0) {
> +               if (stat(path, &sb) == 0) {
>                         ret = unlink(path);
>                         if (ret != 0) {
>                                 ERR(sh, "Error while removing cached CIL file %s: %s", path, strerror(errno));
> diff --git a/libsemanage/src/semanage_store.c b/libsemanage/src/semanage_store.c
> index 4bd1d651..83c188dc 100644
> --- a/libsemanage/src/semanage_store.c
> +++ b/libsemanage/src/semanage_store.c
> @@ -514,6 +514,7 @@ char *semanage_conf_path(void)
>  {
>         char *semanage_conf = NULL;
>         int len;
> +       FILE *fp = NULL;
>
>         len = strlen(semanage_root()) + strlen(selinux_path()) + strlen(SEMANAGE_CONF_FILE);
>         semanage_conf = calloc(len + 1, sizeof(char));
> @@ -522,7 +523,10 @@ char *semanage_conf_path(void)
>         snprintf(semanage_conf, len + 1, "%s%s%s", semanage_root(), selinux_path(),
>                  SEMANAGE_CONF_FILE);
>
> -       if (access(semanage_conf, R_OK) != 0) {
> +       //the following replaces access(semanage_conf, R_OK) check
> +       if ((fp = fopen(semanage_conf, "r")) != NULL) {
> +               fclose(fp);
> +       } else {
>                 snprintf(semanage_conf, len + 1, "%s%s", selinux_path(), SEMANAGE_CONF_FILE);
>         }
>
> @@ -1508,8 +1512,14 @@ int semanage_split_fc(semanage_handle_t * sh)
>  static int sefcontext_compile(semanage_handle_t * sh, const char *path) {
>
>         int r;
> +       struct stat sb;
> +
> +       if (stat(path, &sb) < 0) {
> +               if (errno != ENOENT) {
> +                       ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
> +                       return -1;
> +               }
>
> -       if (access(path, F_OK) != 0) {
>                 return 0;
>         }
>
> --
> 2.14.3
>
>



-- 
Respectfully,

William C Roberts

Re: [PATCH 3/3] libsemanage: replace access() checks to make setuid programs work

[William Roberts]

Where is patch 2/2, I have yet to see it?

Did something get screwy and is it: [PATCH] libsemanage: Improve
warning for installing disabled module


On Wed, Feb 28, 2018 at 9:50 AM, William Roberts
<bill.c.roberts@gmail.com> wrote:
> On Wed, Feb 28, 2018 at 2:15 AM, Vit Mojzis <vmojzis@redhat.com> wrote:
>> access() uses real UID instead of effective UID which causes false
>> negative checks in setuid programs.
>> Replace access(,F_OK) (i.e. tests for file existence) by stat().
>> And access(,R_OK) by fopen(,"r")
>>
>> Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1186431
>>
>> Signed-off-by: Vit Mojzis <vmojzis@redhat.com>
>> ---
>>  libsemanage/src/direct_api.c     | 132 +++++++++++++++++++++++++--------------
>>  libsemanage/src/semanage_store.c |  14 ++++-
>>  2 files changed, 98 insertions(+), 48 deletions(-)
>>
>> diff --git a/libsemanage/src/direct_api.c b/libsemanage/src/direct_api.c
>> index f4d57cf8..d42a51cd 100644
>> --- a/libsemanage/src/direct_api.c
>> +++ b/libsemanage/src/direct_api.c
>> @@ -140,6 +140,7 @@ int semanage_direct_is_managed(semanage_handle_t * sh)
>>  int semanage_direct_connect(semanage_handle_t * sh)
>>  {
>>         const char *path;
>> +       struct stat sb;
>>
>>         if (semanage_check_init(sh, sh->conf->store_root_path))
>>                 goto err;
>> @@ -302,10 +303,17 @@ int semanage_direct_connect(semanage_handle_t * sh)
>>
>>         /* set the disable dontaudit value */
>>         path = semanage_path(SEMANAGE_ACTIVE, SEMANAGE_DISABLE_DONTAUDIT);
>> -       if (access(path, F_OK) == 0)
>> +
>> +       if (stat(path, &sb) == 0)
>>                 sepol_set_disable_dontaudit(sh->sepolh, 1);
>> -       else
>> +       else {
>> +               if (errno != ENOENT) {
>> +                       ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
>> +                       goto err;
>> +               }
>> +
>>                 sepol_set_disable_dontaudit(sh->sepolh, 0);
>> +       }
>>
>>         return STATUS_SUCCESS;
>>
>> @@ -1139,6 +1147,7 @@ static int semanage_compile_hll_modules(semanage_handle_t *sh,
>>         int status = 0;
>>         int i;
>>         char cil_path[PATH_MAX];
>> +       struct stat sb;
>>
>>         assert(sh);
>>         assert(modinfos);
>> @@ -1155,9 +1164,13 @@ static int semanage_compile_hll_modules(semanage_handle_t *sh,
>>                 }
>>
>>                 if (semanage_get_ignore_module_cache(sh) == 0 &&
>> -                               access(cil_path, F_OK) == 0) {
>> +                               (status = stat(cil_path, &sb)) == 0) {
>>                         continue;
>>                 }
>> +               if (status != 0 && errno != ENOENT) {
>> +                       ERR(sh, "Unable to access %s: %s\n", cil_path, strerror(errno));
>> +                       goto cleanup; //an error in the "stat" call
>> +               }
>>
>>                 status = semanage_compile_module(sh, &modinfos[i]);
>>                 if (status < 0) {
>> @@ -1188,6 +1201,7 @@ static int semanage_direct_commit(semanage_handle_t * sh)
>>         struct cil_db *cildb = NULL;
>>         semanage_module_info_t *modinfos = NULL;
>>         mode_t mask = umask(0077);
>> +       struct stat sb;
>>
>>         int do_rebuild, do_write_kernel, do_install;
>>         int fcontexts_modified, ports_modified, seusers_modified,
>> @@ -1226,10 +1240,16 @@ static int semanage_direct_commit(semanage_handle_t * sh)
>>
>>         /* Create or remove the disable_dontaudit flag file. */
>>         path = semanage_path(SEMANAGE_TMP, SEMANAGE_DISABLE_DONTAUDIT);
>> -       if (access(path, F_OK) == 0)
>> +       if (stat(path, &sb) == 0)
>>                 do_rebuild |= !(sepol_get_disable_dontaudit(sh->sepolh) == 1);
>> -       else
>> +       else {
>> +               if (errno != ENOENT) {
>> +                       ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
>> +                       goto cleanup;
>> +               }
>> +
>
> I am not a huge fan of this if under else block of if (errno !=ENOENT).
>
> maybe this is a bit cleaner:
>
> if (stat() == 0)
>   //exists
> else if (errno == ENOENT)
>   // doesn't exist
> else
>   //fail
>
>>                 do_rebuild |= (sepol_get_disable_dontaudit(sh->sepolh) == 1);
>> +       }
>>         if (sepol_get_disable_dontaudit(sh->sepolh) == 1) {
>>                 FILE *touch;
>>                 touch = fopen(path, "w");
>> @@ -1251,10 +1271,17 @@ static int semanage_direct_commit(semanage_handle_t * sh)
>>
>>         /* Create or remove the preserve_tunables flag file. */
>>         path = semanage_path(SEMANAGE_TMP, SEMANAGE_PRESERVE_TUNABLES);
>> -       if (access(path, F_OK) == 0)
>> +       if (stat(path, &sb) == 0)
>>                 do_rebuild |= !(sepol_get_preserve_tunables(sh->sepolh) == 1);
>> -       else
>> +       else {
>> +               if (errno != ENOENT) {
>> +                       ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
>> +                       goto cleanup;
>> +               }
>> +
>>                 do_rebuild |= (sepol_get_preserve_tunables(sh->sepolh) == 1);
>> +       }
>> +
>>         if (sepol_get_preserve_tunables(sh->sepolh) == 1) {
>>                 FILE *touch;
>>                 touch = fopen(path, "w");
>> @@ -1291,40 +1318,24 @@ static int semanage_direct_commit(semanage_handle_t * sh)
>>          * a rebuild.
>>          */
>>         if (!do_rebuild) {
>> -               path = semanage_path(SEMANAGE_TMP, SEMANAGE_STORE_KERNEL);
>> -               if (access(path, F_OK) != 0) {
>> -                       do_rebuild = 1;
>> -                       goto rebuild;
>> -               }
>> -
>> -               path = semanage_path(SEMANAGE_TMP, SEMANAGE_STORE_FC);
>> -               if (access(path, F_OK) != 0) {
>> -                       do_rebuild = 1;
>> -                       goto rebuild;
>> -               }
>> -
>> -               path = semanage_path(SEMANAGE_TMP, SEMANAGE_STORE_SEUSERS);
>> -               if (access(path, F_OK) != 0) {
>> -                       do_rebuild = 1;
>> -                       goto rebuild;
>> -               }
>> -
>> -               path = semanage_path(SEMANAGE_TMP, SEMANAGE_LINKED);
>> -               if (access(path, F_OK) != 0) {
>> -                       do_rebuild = 1;
>> -                       goto rebuild;
>> -               }
>> -
>> -               path = semanage_path(SEMANAGE_TMP, SEMANAGE_SEUSERS_LINKED);
>> -               if (access(path, F_OK) != 0) {
>> -                       do_rebuild = 1;
>> -                       goto rebuild;
>> -               }
>> +               int files[] = {SEMANAGE_STORE_KERNEL,
>> +                                          SEMANAGE_STORE_FC,
>> +                                          SEMANAGE_STORE_SEUSERS,
>> +                                          SEMANAGE_LINKED,
>> +                                          SEMANAGE_SEUSERS_LINKED,
>> +                                          SEMANAGE_USERS_EXTRA_LINKED};
>> +
>> +               for (i = 0; i < (int) sizeof(files); i++) {
>> +                       path = semanage_path(SEMANAGE_TMP, files[i]);
>> +                       if (stat(path, &sb) != 0) {
>> +                               if (errno != ENOENT) {
>> +                                       ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
>> +                                       goto cleanup;
>> +                               }
>>
>> -               path = semanage_path(SEMANAGE_TMP, SEMANAGE_USERS_EXTRA_LINKED);
>> -               if (access(path, F_OK) != 0) {
>> -                       do_rebuild = 1;
>> -                       goto rebuild;
>> +                               do_rebuild = 1;
>> +                               goto rebuild;
>> +                       }
>>                 }
>>         }
>>
>> @@ -1457,7 +1468,7 @@ rebuild:
>>                         goto cleanup;
>>
>>                 path = semanage_path(SEMANAGE_TMP, SEMANAGE_SEUSERS_LINKED);
>> -               if (access(path, F_OK) == 0) {
>> +               if (stat(path, &sb) == 0) {
>>                         retval = semanage_copy_file(path,
>>                                                     semanage_path(SEMANAGE_TMP,
>>                                                                   SEMANAGE_STORE_SEUSERS),
>> @@ -1466,11 +1477,16 @@ rebuild:
>>                                 goto cleanup;
>>                         pseusers->dtable->drop_cache(pseusers->dbase);
>>                 } else {
>> +                       if (errno != ENOENT) {
>> +                               ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
>> +                               goto cleanup;
>> +                       }
>> +
>>                         pseusers->dtable->clear(sh, pseusers->dbase);
>>                 }
>>
>>                 path = semanage_path(SEMANAGE_TMP, SEMANAGE_USERS_EXTRA_LINKED);
>> -               if (access(path, F_OK) == 0) {
>> +               if (stat(path, &sb) == 0) {
>>                         retval = semanage_copy_file(path,
>>                                                     semanage_path(SEMANAGE_TMP,
>>                                                                   SEMANAGE_USERS_EXTRA),
>> @@ -1479,6 +1495,11 @@ rebuild:
>>                                 goto cleanup;
>>                         pusers_extra->dtable->drop_cache(pusers_extra->dbase);
>>                 } else {
>> +                       if (errno != ENOENT) {
>> +                               ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
>> +                               goto cleanup;
>> +                       }
>> +
>>                         pusers_extra->dtable->clear(sh, pusers_extra->dbase);
>>                 }
>>         }
>> @@ -1809,6 +1830,7 @@ static int semanage_direct_extract(semanage_handle_t * sh,
>>         ssize_t _data_len;
>>         char *_data;
>>         int compressed;
>> +       struct stat sb;
>>
>>         /* get path of module */
>>         rc = semanage_module_get_path(
>> @@ -1821,8 +1843,8 @@ static int semanage_direct_extract(semanage_handle_t * sh,
>>                 goto cleanup;
>>         }
>>
>> -       if (access(module_path, F_OK) != 0) {
>> -               ERR(sh, "Module does not exist: %s", module_path);
>> +       if (stat(module_path, &sb) != 0) {
>> +               ERR(sh, "Unable to access %s: %s\n", module_path, strerror(errno));
>>                 rc = -1;
>>                 goto cleanup;
>>         }
>> @@ -1851,7 +1873,12 @@ static int semanage_direct_extract(semanage_handle_t * sh,
>>                 goto cleanup;
>>         }
>>
>> -       if (extract_cil == 1 && strcmp(_modinfo->lang_ext, "cil") && access(input_file, F_OK) != 0) {
>> +       if (extract_cil == 1 && strcmp(_modinfo->lang_ext, "cil") && stat(input_file, &sb) != 0) {
>> +               if (errno != ENOENT) {
>> +                       ERR(sh, "Unable to access %s: %s\n", input_file, strerror(errno));
>> +                       goto cleanup;
>> +               }
>> +
>>                 rc = semanage_compile_module(sh, _modinfo);
>>                 if (rc < 0) {
>>                         goto cleanup;
>> @@ -1996,6 +2023,12 @@ static int semanage_direct_get_enabled(semanage_handle_t *sh,
>>         }
>>
>>         if (stat(path, &sb) < 0) {
>> +               if (errno != ENOENT) {
>> +                       ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
>> +                       status = -1;
>> +                       goto cleanup;
>> +               }
>> +
>>                 *enabled = 1;
>>         }
>>         else {
>> @@ -2322,6 +2355,12 @@ static int semanage_direct_get_module_info(semanage_handle_t *sh,
>>
>>         /* set enabled/disabled status */
>>         if (stat(fn, &sb) < 0) {
>> +               if (errno != ENOENT) {
>> +                       ERR(sh, "Unable to access %s: %s\n", fn, strerror(errno));
>> +                       status = -1;
>> +                       goto cleanup;
>> +               }
>> +
>>                 ret = semanage_module_info_set_enabled(sh, *modinfo, 1);
>>                 if (ret != 0) {
>>                         status = -1;
>> @@ -2730,6 +2769,7 @@ static int semanage_direct_install_info(semanage_handle_t *sh,
>>         int status = 0;
>>         int ret = 0;
>>         int type;
>> +       struct stat sb;
>>
>>         char path[PATH_MAX];
>>         mode_t mask = umask(0077);
>> @@ -2830,7 +2870,7 @@ static int semanage_direct_install_info(semanage_handle_t *sh,
>>                         goto cleanup;
>>                 }
>>
>> -               if (access(path, F_OK) == 0) {
>> +               if (stat(path, &sb) == 0) {
>>                         ret = unlink(path);
>>                         if (ret != 0) {
>>                                 ERR(sh, "Error while removing cached CIL file %s: %s", path, strerror(errno));
>> diff --git a/libsemanage/src/semanage_store.c b/libsemanage/src/semanage_store.c
>> index 4bd1d651..83c188dc 100644
>> --- a/libsemanage/src/semanage_store.c
>> +++ b/libsemanage/src/semanage_store.c
>> @@ -514,6 +514,7 @@ char *semanage_conf_path(void)
>>  {
>>         char *semanage_conf = NULL;
>>         int len;
>> +       FILE *fp = NULL;
>>
>>         len = strlen(semanage_root()) + strlen(selinux_path()) + strlen(SEMANAGE_CONF_FILE);
>>         semanage_conf = calloc(len + 1, sizeof(char));
>> @@ -522,7 +523,10 @@ char *semanage_conf_path(void)
>>         snprintf(semanage_conf, len + 1, "%s%s%s", semanage_root(), selinux_path(),
>>                  SEMANAGE_CONF_FILE);
>>
>> -       if (access(semanage_conf, R_OK) != 0) {
>> +       //the following replaces access(semanage_conf, R_OK) check
>> +       if ((fp = fopen(semanage_conf, "r")) != NULL) {
>> +               fclose(fp);
>> +       } else {
>>                 snprintf(semanage_conf, len + 1, "%s%s", selinux_path(), SEMANAGE_CONF_FILE);
>>         }
>>
>> @@ -1508,8 +1512,14 @@ int semanage_split_fc(semanage_handle_t * sh)
>>  static int sefcontext_compile(semanage_handle_t * sh, const char *path) {
>>
>>         int r;
>> +       struct stat sb;
>> +
>> +       if (stat(path, &sb) < 0) {
>> +               if (errno != ENOENT) {
>> +                       ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
>> +                       return -1;
>> +               }
>>
>> -       if (access(path, F_OK) != 0) {
>>                 return 0;
>>         }
>>
>> --
>> 2.14.3
>>
>>
>
>
>
> --
> Respectfully,
>
> William C Roberts



-- 
Respectfully,

William C Roberts

Re: [PATCH 3/3] libsemanage: replace access() checks to make setuid programs work

[Stephen Smalley]

On 02/28/2018 01:24 PM, William Roberts wrote:
> Where is patch 2/2, I have yet to see it?
> 
> Did something get screwy and is it: [PATCH] libsemanage: Improve
> warning for installing disabled module

No, 2/3 was a separate patch and had the 2/3 in the subject line.
I received all three from the list, both locally and on my gmail.

> 
> 
> On Wed, Feb 28, 2018 at 9:50 AM, William Roberts
> <bill.c.roberts@gmail.com> wrote:
>> On Wed, Feb 28, 2018 at 2:15 AM, Vit Mojzis <vmojzis@redhat.com> wrote:
>>> access() uses real UID instead of effective UID which causes false
>>> negative checks in setuid programs.
>>> Replace access(,F_OK) (i.e. tests for file existence) by stat().
>>> And access(,R_OK) by fopen(,"r")
>>>
>>> Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1186431
>>>
>>> Signed-off-by: Vit Mojzis <vmojzis@redhat.com>
>>> ---
>>>  libsemanage/src/direct_api.c     | 132 +++++++++++++++++++++++++--------------
>>>  libsemanage/src/semanage_store.c |  14 ++++-
>>>  2 files changed, 98 insertions(+), 48 deletions(-)
>>>
>>> diff --git a/libsemanage/src/direct_api.c b/libsemanage/src/direct_api.c
>>> index f4d57cf8..d42a51cd 100644
>>> --- a/libsemanage/src/direct_api.c
>>> +++ b/libsemanage/src/direct_api.c
>>> @@ -140,6 +140,7 @@ int semanage_direct_is_managed(semanage_handle_t * sh)
>>>  int semanage_direct_connect(semanage_handle_t * sh)
>>>  {
>>>         const char *path;
>>> +       struct stat sb;
>>>
>>>         if (semanage_check_init(sh, sh->conf->store_root_path))
>>>                 goto err;
>>> @@ -302,10 +303,17 @@ int semanage_direct_connect(semanage_handle_t * sh)
>>>
>>>         /* set the disable dontaudit value */
>>>         path = semanage_path(SEMANAGE_ACTIVE, SEMANAGE_DISABLE_DONTAUDIT);
>>> -       if (access(path, F_OK) == 0)
>>> +
>>> +       if (stat(path, &sb) == 0)
>>>                 sepol_set_disable_dontaudit(sh->sepolh, 1);
>>> -       else
>>> +       else {
>>> +               if (errno != ENOENT) {
>>> +                       ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
>>> +                       goto err;
>>> +               }
>>> +
>>>                 sepol_set_disable_dontaudit(sh->sepolh, 0);
>>> +       }
>>>
>>>         return STATUS_SUCCESS;
>>>
>>> @@ -1139,6 +1147,7 @@ static int semanage_compile_hll_modules(semanage_handle_t *sh,
>>>         int status = 0;
>>>         int i;
>>>         char cil_path[PATH_MAX];
>>> +       struct stat sb;
>>>
>>>         assert(sh);
>>>         assert(modinfos);
>>> @@ -1155,9 +1164,13 @@ static int semanage_compile_hll_modules(semanage_handle_t *sh,
>>>                 }
>>>
>>>                 if (semanage_get_ignore_module_cache(sh) == 0 &&
>>> -                               access(cil_path, F_OK) == 0) {
>>> +                               (status = stat(cil_path, &sb)) == 0) {
>>>                         continue;
>>>                 }
>>> +               if (status != 0 && errno != ENOENT) {
>>> +                       ERR(sh, "Unable to access %s: %s\n", cil_path, strerror(errno));
>>> +                       goto cleanup; //an error in the "stat" call
>>> +               }
>>>
>>>                 status = semanage_compile_module(sh, &modinfos[i]);
>>>                 if (status < 0) {
>>> @@ -1188,6 +1201,7 @@ static int semanage_direct_commit(semanage_handle_t * sh)
>>>         struct cil_db *cildb = NULL;
>>>         semanage_module_info_t *modinfos = NULL;
>>>         mode_t mask = umask(0077);
>>> +       struct stat sb;
>>>
>>>         int do_rebuild, do_write_kernel, do_install;
>>>         int fcontexts_modified, ports_modified, seusers_modified,
>>> @@ -1226,10 +1240,16 @@ static int semanage_direct_commit(semanage_handle_t * sh)
>>>
>>>         /* Create or remove the disable_dontaudit flag file. */
>>>         path = semanage_path(SEMANAGE_TMP, SEMANAGE_DISABLE_DONTAUDIT);
>>> -       if (access(path, F_OK) == 0)
>>> +       if (stat(path, &sb) == 0)
>>>                 do_rebuild |= !(sepol_get_disable_dontaudit(sh->sepolh) == 1);
>>> -       else
>>> +       else {
>>> +               if (errno != ENOENT) {
>>> +                       ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
>>> +                       goto cleanup;
>>> +               }
>>> +
>>
>> I am not a huge fan of this if under else block of if (errno !=ENOENT).
>>
>> maybe this is a bit cleaner:
>>
>> if (stat() == 0)
>>   //exists
>> else if (errno == ENOENT)
>>   // doesn't exist
>> else
>>   //fail
>>
>>>                 do_rebuild |= (sepol_get_disable_dontaudit(sh->sepolh) == 1);
>>> +       }
>>>         if (sepol_get_disable_dontaudit(sh->sepolh) == 1) {
>>>                 FILE *touch;
>>>                 touch = fopen(path, "w");
>>> @@ -1251,10 +1271,17 @@ static int semanage_direct_commit(semanage_handle_t * sh)
>>>
>>>         /* Create or remove the preserve_tunables flag file. */
>>>         path = semanage_path(SEMANAGE_TMP, SEMANAGE_PRESERVE_TUNABLES);
>>> -       if (access(path, F_OK) == 0)
>>> +       if (stat(path, &sb) == 0)
>>>                 do_rebuild |= !(sepol_get_preserve_tunables(sh->sepolh) == 1);
>>> -       else
>>> +       else {
>>> +               if (errno != ENOENT) {
>>> +                       ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
>>> +                       goto cleanup;
>>> +               }
>>> +
>>>                 do_rebuild |= (sepol_get_preserve_tunables(sh->sepolh) == 1);
>>> +       }
>>> +
>>>         if (sepol_get_preserve_tunables(sh->sepolh) == 1) {
>>>                 FILE *touch;
>>>                 touch = fopen(path, "w");
>>> @@ -1291,40 +1318,24 @@ static int semanage_direct_commit(semanage_handle_t * sh)
>>>          * a rebuild.
>>>          */
>>>         if (!do_rebuild) {
>>> -               path = semanage_path(SEMANAGE_TMP, SEMANAGE_STORE_KERNEL);
>>> -               if (access(path, F_OK) != 0) {
>>> -                       do_rebuild = 1;
>>> -                       goto rebuild;
>>> -               }
>>> -
>>> -               path = semanage_path(SEMANAGE_TMP, SEMANAGE_STORE_FC);
>>> -               if (access(path, F_OK) != 0) {
>>> -                       do_rebuild = 1;
>>> -                       goto rebuild;
>>> -               }
>>> -
>>> -               path = semanage_path(SEMANAGE_TMP, SEMANAGE_STORE_SEUSERS);
>>> -               if (access(path, F_OK) != 0) {
>>> -                       do_rebuild = 1;
>>> -                       goto rebuild;
>>> -               }
>>> -
>>> -               path = semanage_path(SEMANAGE_TMP, SEMANAGE_LINKED);
>>> -               if (access(path, F_OK) != 0) {
>>> -                       do_rebuild = 1;
>>> -                       goto rebuild;
>>> -               }
>>> -
>>> -               path = semanage_path(SEMANAGE_TMP, SEMANAGE_SEUSERS_LINKED);
>>> -               if (access(path, F_OK) != 0) {
>>> -                       do_rebuild = 1;
>>> -                       goto rebuild;
>>> -               }
>>> +               int files[] = {SEMANAGE_STORE_KERNEL,
>>> +                                          SEMANAGE_STORE_FC,
>>> +                                          SEMANAGE_STORE_SEUSERS,
>>> +                                          SEMANAGE_LINKED,
>>> +                                          SEMANAGE_SEUSERS_LINKED,
>>> +                                          SEMANAGE_USERS_EXTRA_LINKED};
>>> +
>>> +               for (i = 0; i < (int) sizeof(files); i++) {
>>> +                       path = semanage_path(SEMANAGE_TMP, files[i]);
>>> +                       if (stat(path, &sb) != 0) {
>>> +                               if (errno != ENOENT) {
>>> +                                       ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
>>> +                                       goto cleanup;
>>> +                               }
>>>
>>> -               path = semanage_path(SEMANAGE_TMP, SEMANAGE_USERS_EXTRA_LINKED);
>>> -               if (access(path, F_OK) != 0) {
>>> -                       do_rebuild = 1;
>>> -                       goto rebuild;
>>> +                               do_rebuild = 1;
>>> +                               goto rebuild;
>>> +                       }
>>>                 }
>>>         }
>>>
>>> @@ -1457,7 +1468,7 @@ rebuild:
>>>                         goto cleanup;
>>>
>>>                 path = semanage_path(SEMANAGE_TMP, SEMANAGE_SEUSERS_LINKED);
>>> -               if (access(path, F_OK) == 0) {
>>> +               if (stat(path, &sb) == 0) {
>>>                         retval = semanage_copy_file(path,
>>>                                                     semanage_path(SEMANAGE_TMP,
>>>                                                                   SEMANAGE_STORE_SEUSERS),
>>> @@ -1466,11 +1477,16 @@ rebuild:
>>>                                 goto cleanup;
>>>                         pseusers->dtable->drop_cache(pseusers->dbase);
>>>                 } else {
>>> +                       if (errno != ENOENT) {
>>> +                               ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
>>> +                               goto cleanup;
>>> +                       }
>>> +
>>>                         pseusers->dtable->clear(sh, pseusers->dbase);
>>>                 }
>>>
>>>                 path = semanage_path(SEMANAGE_TMP, SEMANAGE_USERS_EXTRA_LINKED);
>>> -               if (access(path, F_OK) == 0) {
>>> +               if (stat(path, &sb) == 0) {
>>>                         retval = semanage_copy_file(path,
>>>                                                     semanage_path(SEMANAGE_TMP,
>>>                                                                   SEMANAGE_USERS_EXTRA),
>>> @@ -1479,6 +1495,11 @@ rebuild:
>>>                                 goto cleanup;
>>>                         pusers_extra->dtable->drop_cache(pusers_extra->dbase);
>>>                 } else {
>>> +                       if (errno != ENOENT) {
>>> +                               ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
>>> +                               goto cleanup;
>>> +                       }
>>> +
>>>                         pusers_extra->dtable->clear(sh, pusers_extra->dbase);
>>>                 }
>>>         }
>>> @@ -1809,6 +1830,7 @@ static int semanage_direct_extract(semanage_handle_t * sh,
>>>         ssize_t _data_len;
>>>         char *_data;
>>>         int compressed;
>>> +       struct stat sb;
>>>
>>>         /* get path of module */
>>>         rc = semanage_module_get_path(
>>> @@ -1821,8 +1843,8 @@ static int semanage_direct_extract(semanage_handle_t * sh,
>>>                 goto cleanup;
>>>         }
>>>
>>> -       if (access(module_path, F_OK) != 0) {
>>> -               ERR(sh, "Module does not exist: %s", module_path);
>>> +       if (stat(module_path, &sb) != 0) {
>>> +               ERR(sh, "Unable to access %s: %s\n", module_path, strerror(errno));
>>>                 rc = -1;
>>>                 goto cleanup;
>>>         }
>>> @@ -1851,7 +1873,12 @@ static int semanage_direct_extract(semanage_handle_t * sh,
>>>                 goto cleanup;
>>>         }
>>>
>>> -       if (extract_cil == 1 && strcmp(_modinfo->lang_ext, "cil") && access(input_file, F_OK) != 0) {
>>> +       if (extract_cil == 1 && strcmp(_modinfo->lang_ext, "cil") && stat(input_file, &sb) != 0) {
>>> +               if (errno != ENOENT) {
>>> +                       ERR(sh, "Unable to access %s: %s\n", input_file, strerror(errno));
>>> +                       goto cleanup;
>>> +               }
>>> +
>>>                 rc = semanage_compile_module(sh, _modinfo);
>>>                 if (rc < 0) {
>>>                         goto cleanup;
>>> @@ -1996,6 +2023,12 @@ static int semanage_direct_get_enabled(semanage_handle_t *sh,
>>>         }
>>>
>>>         if (stat(path, &sb) < 0) {
>>> +               if (errno != ENOENT) {
>>> +                       ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
>>> +                       status = -1;
>>> +                       goto cleanup;
>>> +               }
>>> +
>>>                 *enabled = 1;
>>>         }
>>>         else {
>>> @@ -2322,6 +2355,12 @@ static int semanage_direct_get_module_info(semanage_handle_t *sh,
>>>
>>>         /* set enabled/disabled status */
>>>         if (stat(fn, &sb) < 0) {
>>> +               if (errno != ENOENT) {
>>> +                       ERR(sh, "Unable to access %s: %s\n", fn, strerror(errno));
>>> +                       status = -1;
>>> +                       goto cleanup;
>>> +               }
>>> +
>>>                 ret = semanage_module_info_set_enabled(sh, *modinfo, 1);
>>>                 if (ret != 0) {
>>>                         status = -1;
>>> @@ -2730,6 +2769,7 @@ static int semanage_direct_install_info(semanage_handle_t *sh,
>>>         int status = 0;
>>>         int ret = 0;
>>>         int type;
>>> +       struct stat sb;
>>>
>>>         char path[PATH_MAX];
>>>         mode_t mask = umask(0077);
>>> @@ -2830,7 +2870,7 @@ static int semanage_direct_install_info(semanage_handle_t *sh,
>>>                         goto cleanup;
>>>                 }
>>>
>>> -               if (access(path, F_OK) == 0) {
>>> +               if (stat(path, &sb) == 0) {
>>>                         ret = unlink(path);
>>>                         if (ret != 0) {
>>>                                 ERR(sh, "Error while removing cached CIL file %s: %s", path, strerror(errno));
>>> diff --git a/libsemanage/src/semanage_store.c b/libsemanage/src/semanage_store.c
>>> index 4bd1d651..83c188dc 100644
>>> --- a/libsemanage/src/semanage_store.c
>>> +++ b/libsemanage/src/semanage_store.c
>>> @@ -514,6 +514,7 @@ char *semanage_conf_path(void)
>>>  {
>>>         char *semanage_conf = NULL;
>>>         int len;
>>> +       FILE *fp = NULL;
>>>
>>>         len = strlen(semanage_root()) + strlen(selinux_path()) + strlen(SEMANAGE_CONF_FILE);
>>>         semanage_conf = calloc(len + 1, sizeof(char));
>>> @@ -522,7 +523,10 @@ char *semanage_conf_path(void)
>>>         snprintf(semanage_conf, len + 1, "%s%s%s", semanage_root(), selinux_path(),
>>>                  SEMANAGE_CONF_FILE);
>>>
>>> -       if (access(semanage_conf, R_OK) != 0) {
>>> +       //the following replaces access(semanage_conf, R_OK) check
>>> +       if ((fp = fopen(semanage_conf, "r")) != NULL) {
>>> +               fclose(fp);
>>> +       } else {
>>>                 snprintf(semanage_conf, len + 1, "%s%s", selinux_path(), SEMANAGE_CONF_FILE);
>>>         }
>>>
>>> @@ -1508,8 +1512,14 @@ int semanage_split_fc(semanage_handle_t * sh)
>>>  static int sefcontext_compile(semanage_handle_t * sh, const char *path) {
>>>
>>>         int r;
>>> +       struct stat sb;
>>> +
>>> +       if (stat(path, &sb) < 0) {
>>> +               if (errno != ENOENT) {
>>> +                       ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
>>> +                       return -1;
>>> +               }
>>>
>>> -       if (access(path, F_OK) != 0) {
>>>                 return 0;
>>>         }
>>>
>>> --
>>> 2.14.3
>>>
>>>
>>
>>
>>
>> --
>> Respectfully,
>>
>> William C Roberts
> 
> 
> 

Re: [PATCH 3/3] libsemanage: replace access() checks to make setuid programs work

[William Roberts]

On Wed, Feb 28, 2018 at 10:43 AM, Stephen Smalley <sds@tycho.nsa.gov> wrote:
> On 02/28/2018 01:24 PM, William Roberts wrote:
>> Where is patch 2/2, I have yet to see it?
>>
>> Did something get screwy and is it: [PATCH] libsemanage: Improve
>> warning for installing disabled module
>
> No, 2/3 was a separate patch and had the 2/3 in the subject line.
> I received all three from the list, both locally and on my gmail.
>

Thanks gmail for folding the patch 1/3 and 2/3 into the same "conversation" or
whatever it does.


>>
>>
>> On Wed, Feb 28, 2018 at 9:50 AM, William Roberts
>> <bill.c.roberts@gmail.com> wrote:
>>> On Wed, Feb 28, 2018 at 2:15 AM, Vit Mojzis <vmojzis@redhat.com> wrote:
>>>> access() uses real UID instead of effective UID which causes false
>>>> negative checks in setuid programs.
>>>> Replace access(,F_OK) (i.e. tests for file existence) by stat().
>>>> And access(,R_OK) by fopen(,"r")
>>>>
>>>> Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1186431
>>>>
>>>> Signed-off-by: Vit Mojzis <vmojzis@redhat.com>
>>>> ---
>>>>  libsemanage/src/direct_api.c     | 132 +++++++++++++++++++++++++--------------
>>>>  libsemanage/src/semanage_store.c |  14 ++++-
>>>>  2 files changed, 98 insertions(+), 48 deletions(-)
>>>>
>>>> diff --git a/libsemanage/src/direct_api.c b/libsemanage/src/direct_api.c
>>>> index f4d57cf8..d42a51cd 100644
>>>> --- a/libsemanage/src/direct_api.c
>>>> +++ b/libsemanage/src/direct_api.c
>>>> @@ -140,6 +140,7 @@ int semanage_direct_is_managed(semanage_handle_t * sh)
>>>>  int semanage_direct_connect(semanage_handle_t * sh)
>>>>  {
>>>>         const char *path;
>>>> +       struct stat sb;
>>>>
>>>>         if (semanage_check_init(sh, sh->conf->store_root_path))
>>>>                 goto err;
>>>> @@ -302,10 +303,17 @@ int semanage_direct_connect(semanage_handle_t * sh)
>>>>
>>>>         /* set the disable dontaudit value */
>>>>         path = semanage_path(SEMANAGE_ACTIVE, SEMANAGE_DISABLE_DONTAUDIT);
>>>> -       if (access(path, F_OK) == 0)
>>>> +
>>>> +       if (stat(path, &sb) == 0)
>>>>                 sepol_set_disable_dontaudit(sh->sepolh, 1);
>>>> -       else
>>>> +       else {
>>>> +               if (errno != ENOENT) {
>>>> +                       ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
>>>> +                       goto err;
>>>> +               }
>>>> +
>>>>                 sepol_set_disable_dontaudit(sh->sepolh, 0);
>>>> +       }
>>>>
>>>>         return STATUS_SUCCESS;
>>>>
>>>> @@ -1139,6 +1147,7 @@ static int semanage_compile_hll_modules(semanage_handle_t *sh,
>>>>         int status = 0;
>>>>         int i;
>>>>         char cil_path[PATH_MAX];
>>>> +       struct stat sb;
>>>>
>>>>         assert(sh);
>>>>         assert(modinfos);
>>>> @@ -1155,9 +1164,13 @@ static int semanage_compile_hll_modules(semanage_handle_t *sh,
>>>>                 }
>>>>
>>>>                 if (semanage_get_ignore_module_cache(sh) == 0 &&
>>>> -                               access(cil_path, F_OK) == 0) {
>>>> +                               (status = stat(cil_path, &sb)) == 0) {
>>>>                         continue;
>>>>                 }
>>>> +               if (status != 0 && errno != ENOENT) {
>>>> +                       ERR(sh, "Unable to access %s: %s\n", cil_path, strerror(errno));
>>>> +                       goto cleanup; //an error in the "stat" call
>>>> +               }
>>>>
>>>>                 status = semanage_compile_module(sh, &modinfos[i]);
>>>>                 if (status < 0) {
>>>> @@ -1188,6 +1201,7 @@ static int semanage_direct_commit(semanage_handle_t * sh)
>>>>         struct cil_db *cildb = NULL;
>>>>         semanage_module_info_t *modinfos = NULL;
>>>>         mode_t mask = umask(0077);
>>>> +       struct stat sb;
>>>>
>>>>         int do_rebuild, do_write_kernel, do_install;
>>>>         int fcontexts_modified, ports_modified, seusers_modified,
>>>> @@ -1226,10 +1240,16 @@ static int semanage_direct_commit(semanage_handle_t * sh)
>>>>
>>>>         /* Create or remove the disable_dontaudit flag file. */
>>>>         path = semanage_path(SEMANAGE_TMP, SEMANAGE_DISABLE_DONTAUDIT);
>>>> -       if (access(path, F_OK) == 0)
>>>> +       if (stat(path, &sb) == 0)
>>>>                 do_rebuild |= !(sepol_get_disable_dontaudit(sh->sepolh) == 1);
>>>> -       else
>>>> +       else {
>>>> +               if (errno != ENOENT) {
>>>> +                       ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
>>>> +                       goto cleanup;
>>>> +               }
>>>> +
>>>
>>> I am not a huge fan of this if under else block of if (errno !=ENOENT).
>>>
>>> maybe this is a bit cleaner:
>>>
>>> if (stat() == 0)
>>>   //exists
>>> else if (errno == ENOENT)
>>>   // doesn't exist
>>> else
>>>   //fail
>>>
>>>>                 do_rebuild |= (sepol_get_disable_dontaudit(sh->sepolh) == 1);
>>>> +       }
>>>>         if (sepol_get_disable_dontaudit(sh->sepolh) == 1) {
>>>>                 FILE *touch;
>>>>                 touch = fopen(path, "w");
>>>> @@ -1251,10 +1271,17 @@ static int semanage_direct_commit(semanage_handle_t * sh)
>>>>
>>>>         /* Create or remove the preserve_tunables flag file. */
>>>>         path = semanage_path(SEMANAGE_TMP, SEMANAGE_PRESERVE_TUNABLES);
>>>> -       if (access(path, F_OK) == 0)
>>>> +       if (stat(path, &sb) == 0)
>>>>                 do_rebuild |= !(sepol_get_preserve_tunables(sh->sepolh) == 1);
>>>> -       else
>>>> +       else {
>>>> +               if (errno != ENOENT) {
>>>> +                       ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
>>>> +                       goto cleanup;
>>>> +               }
>>>> +
>>>>                 do_rebuild |= (sepol_get_preserve_tunables(sh->sepolh) == 1);
>>>> +       }
>>>> +
>>>>         if (sepol_get_preserve_tunables(sh->sepolh) == 1) {
>>>>                 FILE *touch;
>>>>                 touch = fopen(path, "w");
>>>> @@ -1291,40 +1318,24 @@ static int semanage_direct_commit(semanage_handle_t * sh)
>>>>          * a rebuild.
>>>>          */
>>>>         if (!do_rebuild) {
>>>> -               path = semanage_path(SEMANAGE_TMP, SEMANAGE_STORE_KERNEL);
>>>> -               if (access(path, F_OK) != 0) {
>>>> -                       do_rebuild = 1;
>>>> -                       goto rebuild;
>>>> -               }
>>>> -
>>>> -               path = semanage_path(SEMANAGE_TMP, SEMANAGE_STORE_FC);
>>>> -               if (access(path, F_OK) != 0) {
>>>> -                       do_rebuild = 1;
>>>> -                       goto rebuild;
>>>> -               }
>>>> -
>>>> -               path = semanage_path(SEMANAGE_TMP, SEMANAGE_STORE_SEUSERS);
>>>> -               if (access(path, F_OK) != 0) {
>>>> -                       do_rebuild = 1;
>>>> -                       goto rebuild;
>>>> -               }
>>>> -
>>>> -               path = semanage_path(SEMANAGE_TMP, SEMANAGE_LINKED);
>>>> -               if (access(path, F_OK) != 0) {
>>>> -                       do_rebuild = 1;
>>>> -                       goto rebuild;
>>>> -               }
>>>> -
>>>> -               path = semanage_path(SEMANAGE_TMP, SEMANAGE_SEUSERS_LINKED);
>>>> -               if (access(path, F_OK) != 0) {
>>>> -                       do_rebuild = 1;
>>>> -                       goto rebuild;
>>>> -               }
>>>> +               int files[] = {SEMANAGE_STORE_KERNEL,
>>>> +                                          SEMANAGE_STORE_FC,
>>>> +                                          SEMANAGE_STORE_SEUSERS,
>>>> +                                          SEMANAGE_LINKED,
>>>> +                                          SEMANAGE_SEUSERS_LINKED,
>>>> +                                          SEMANAGE_USERS_EXTRA_LINKED};
>>>> +
>>>> +               for (i = 0; i < (int) sizeof(files); i++) {
>>>> +                       path = semanage_path(SEMANAGE_TMP, files[i]);
>>>> +                       if (stat(path, &sb) != 0) {
>>>> +                               if (errno != ENOENT) {
>>>> +                                       ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
>>>> +                                       goto cleanup;
>>>> +                               }
>>>>
>>>> -               path = semanage_path(SEMANAGE_TMP, SEMANAGE_USERS_EXTRA_LINKED);
>>>> -               if (access(path, F_OK) != 0) {
>>>> -                       do_rebuild = 1;
>>>> -                       goto rebuild;
>>>> +                               do_rebuild = 1;
>>>> +                               goto rebuild;
>>>> +                       }
>>>>                 }
>>>>         }
>>>>
>>>> @@ -1457,7 +1468,7 @@ rebuild:
>>>>                         goto cleanup;
>>>>
>>>>                 path = semanage_path(SEMANAGE_TMP, SEMANAGE_SEUSERS_LINKED);
>>>> -               if (access(path, F_OK) == 0) {
>>>> +               if (stat(path, &sb) == 0) {
>>>>                         retval = semanage_copy_file(path,
>>>>                                                     semanage_path(SEMANAGE_TMP,
>>>>                                                                   SEMANAGE_STORE_SEUSERS),
>>>> @@ -1466,11 +1477,16 @@ rebuild:
>>>>                                 goto cleanup;
>>>>                         pseusers->dtable->drop_cache(pseusers->dbase);
>>>>                 } else {
>>>> +                       if (errno != ENOENT) {
>>>> +                               ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
>>>> +                               goto cleanup;
>>>> +                       }
>>>> +
>>>>                         pseusers->dtable->clear(sh, pseusers->dbase);
>>>>                 }
>>>>
>>>>                 path = semanage_path(SEMANAGE_TMP, SEMANAGE_USERS_EXTRA_LINKED);
>>>> -               if (access(path, F_OK) == 0) {
>>>> +               if (stat(path, &sb) == 0) {
>>>>                         retval = semanage_copy_file(path,
>>>>                                                     semanage_path(SEMANAGE_TMP,
>>>>                                                                   SEMANAGE_USERS_EXTRA),
>>>> @@ -1479,6 +1495,11 @@ rebuild:
>>>>                                 goto cleanup;
>>>>                         pusers_extra->dtable->drop_cache(pusers_extra->dbase);
>>>>                 } else {
>>>> +                       if (errno != ENOENT) {
>>>> +                               ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
>>>> +                               goto cleanup;
>>>> +                       }
>>>> +
>>>>                         pusers_extra->dtable->clear(sh, pusers_extra->dbase);
>>>>                 }
>>>>         }
>>>> @@ -1809,6 +1830,7 @@ static int semanage_direct_extract(semanage_handle_t * sh,
>>>>         ssize_t _data_len;
>>>>         char *_data;
>>>>         int compressed;
>>>> +       struct stat sb;
>>>>
>>>>         /* get path of module */
>>>>         rc = semanage_module_get_path(
>>>> @@ -1821,8 +1843,8 @@ static int semanage_direct_extract(semanage_handle_t * sh,
>>>>                 goto cleanup;
>>>>         }
>>>>
>>>> -       if (access(module_path, F_OK) != 0) {
>>>> -               ERR(sh, "Module does not exist: %s", module_path);
>>>> +       if (stat(module_path, &sb) != 0) {
>>>> +               ERR(sh, "Unable to access %s: %s\n", module_path, strerror(errno));
>>>>                 rc = -1;
>>>>                 goto cleanup;
>>>>         }
>>>> @@ -1851,7 +1873,12 @@ static int semanage_direct_extract(semanage_handle_t * sh,
>>>>                 goto cleanup;
>>>>         }
>>>>
>>>> -       if (extract_cil == 1 && strcmp(_modinfo->lang_ext, "cil") && access(input_file, F_OK) != 0) {
>>>> +       if (extract_cil == 1 && strcmp(_modinfo->lang_ext, "cil") && stat(input_file, &sb) != 0) {
>>>> +               if (errno != ENOENT) {
>>>> +                       ERR(sh, "Unable to access %s: %s\n", input_file, strerror(errno));
>>>> +                       goto cleanup;
>>>> +               }
>>>> +
>>>>                 rc = semanage_compile_module(sh, _modinfo);
>>>>                 if (rc < 0) {
>>>>                         goto cleanup;
>>>> @@ -1996,6 +2023,12 @@ static int semanage_direct_get_enabled(semanage_handle_t *sh,
>>>>         }
>>>>
>>>>         if (stat(path, &sb) < 0) {
>>>> +               if (errno != ENOENT) {
>>>> +                       ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
>>>> +                       status = -1;
>>>> +                       goto cleanup;
>>>> +               }
>>>> +
>>>>                 *enabled = 1;
>>>>         }
>>>>         else {
>>>> @@ -2322,6 +2355,12 @@ static int semanage_direct_get_module_info(semanage_handle_t *sh,
>>>>
>>>>         /* set enabled/disabled status */
>>>>         if (stat(fn, &sb) < 0) {
>>>> +               if (errno != ENOENT) {
>>>> +                       ERR(sh, "Unable to access %s: %s\n", fn, strerror(errno));
>>>> +                       status = -1;
>>>> +                       goto cleanup;
>>>> +               }
>>>> +
>>>>                 ret = semanage_module_info_set_enabled(sh, *modinfo, 1);
>>>>                 if (ret != 0) {
>>>>                         status = -1;
>>>> @@ -2730,6 +2769,7 @@ static int semanage_direct_install_info(semanage_handle_t *sh,
>>>>         int status = 0;
>>>>         int ret = 0;
>>>>         int type;
>>>> +       struct stat sb;
>>>>
>>>>         char path[PATH_MAX];
>>>>         mode_t mask = umask(0077);
>>>> @@ -2830,7 +2870,7 @@ static int semanage_direct_install_info(semanage_handle_t *sh,
>>>>                         goto cleanup;
>>>>                 }
>>>>
>>>> -               if (access(path, F_OK) == 0) {
>>>> +               if (stat(path, &sb) == 0) {
>>>>                         ret = unlink(path);
>>>>                         if (ret != 0) {
>>>>                                 ERR(sh, "Error while removing cached CIL file %s: %s", path, strerror(errno));
>>>> diff --git a/libsemanage/src/semanage_store.c b/libsemanage/src/semanage_store.c
>>>> index 4bd1d651..83c188dc 100644
>>>> --- a/libsemanage/src/semanage_store.c
>>>> +++ b/libsemanage/src/semanage_store.c
>>>> @@ -514,6 +514,7 @@ char *semanage_conf_path(void)
>>>>  {
>>>>         char *semanage_conf = NULL;
>>>>         int len;
>>>> +       FILE *fp = NULL;
>>>>
>>>>         len = strlen(semanage_root()) + strlen(selinux_path()) + strlen(SEMANAGE_CONF_FILE);
>>>>         semanage_conf = calloc(len + 1, sizeof(char));
>>>> @@ -522,7 +523,10 @@ char *semanage_conf_path(void)
>>>>         snprintf(semanage_conf, len + 1, "%s%s%s", semanage_root(), selinux_path(),
>>>>                  SEMANAGE_CONF_FILE);
>>>>
>>>> -       if (access(semanage_conf, R_OK) != 0) {
>>>> +       //the following replaces access(semanage_conf, R_OK) check
>>>> +       if ((fp = fopen(semanage_conf, "r")) != NULL) {
>>>> +               fclose(fp);
>>>> +       } else {
>>>>                 snprintf(semanage_conf, len + 1, "%s%s", selinux_path(), SEMANAGE_CONF_FILE);
>>>>         }
>>>>
>>>> @@ -1508,8 +1512,14 @@ int semanage_split_fc(semanage_handle_t * sh)
>>>>  static int sefcontext_compile(semanage_handle_t * sh, const char *path) {
>>>>
>>>>         int r;
>>>> +       struct stat sb;
>>>> +
>>>> +       if (stat(path, &sb) < 0) {
>>>> +               if (errno != ENOENT) {
>>>> +                       ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
>>>> +                       return -1;
>>>> +               }
>>>>
>>>> -       if (access(path, F_OK) != 0) {
>>>>                 return 0;
>>>>         }
>>>>
>>>> --
>>>> 2.14.3
>>>>
>>>>

Re: [PATCH 3/3] libsemanage: replace access() checks to make setuid programs work

[William Roberts]

So peeking through the code base, I see:

int semanage_direct_is_managed(semanage_handle_t * sh)
{
if (semanage_check_init(sh, sh->conf->store_root_path))
goto err;

if (semanage_access_check(sh) < 0)
return 0;

return 1;

      err:
ERR(sh, "could not check whether policy is managed");
return STATUS_ERR;
}

Which semanage_access_check eventually gets down to a raw access check.

Which is only ever used in test_fcontext

semanage_access_check is also the only consumer of semanage_direct_access_check

which is the semanage_store_access_check is only consumed by the
former and test case and
the same could be said for semanage_store_access_check

I think this is a good time to roll in patch 4 and drop everything
relying on semanage_store_access_check.

Thoughts?

On Wed, Feb 28, 2018 at 11:07 AM, William Roberts
<bill.c.roberts@gmail.com> wrote:
> On Wed, Feb 28, 2018 at 10:43 AM, Stephen Smalley <sds@tycho.nsa.gov> wrote:
>> On 02/28/2018 01:24 PM, William Roberts wrote:
>>> Where is patch 2/2, I have yet to see it?
>>>
>>> Did something get screwy and is it: [PATCH] libsemanage: Improve
>>> warning for installing disabled module
>>
>> No, 2/3 was a separate patch and had the 2/3 in the subject line.
>> I received all three from the list, both locally and on my gmail.
>>
>
> Thanks gmail for folding the patch 1/3 and 2/3 into the same "conversation" or
> whatever it does.
>
>
>>>
>>>
>>> On Wed, Feb 28, 2018 at 9:50 AM, William Roberts
>>> <bill.c.roberts@gmail.com> wrote:
>>>> On Wed, Feb 28, 2018 at 2:15 AM, Vit Mojzis <vmojzis@redhat.com> wrote:
>>>>> access() uses real UID instead of effective UID which causes false
>>>>> negative checks in setuid programs.
>>>>> Replace access(,F_OK) (i.e. tests for file existence) by stat().
>>>>> And access(,R_OK) by fopen(,"r")
>>>>>
>>>>> Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1186431
>>>>>
>>>>> Signed-off-by: Vit Mojzis <vmojzis@redhat.com>
>>>>> ---
>>>>>  libsemanage/src/direct_api.c     | 132 +++++++++++++++++++++++++--------------
>>>>>  libsemanage/src/semanage_store.c |  14 ++++-
>>>>>  2 files changed, 98 insertions(+), 48 deletions(-)
>>>>>
>>>>> diff --git a/libsemanage/src/direct_api.c b/libsemanage/src/direct_api.c
>>>>> index f4d57cf8..d42a51cd 100644
>>>>> --- a/libsemanage/src/direct_api.c
>>>>> +++ b/libsemanage/src/direct_api.c
>>>>> @@ -140,6 +140,7 @@ int semanage_direct_is_managed(semanage_handle_t * sh)
>>>>>  int semanage_direct_connect(semanage_handle_t * sh)
>>>>>  {
>>>>>         const char *path;
>>>>> +       struct stat sb;
>>>>>
>>>>>         if (semanage_check_init(sh, sh->conf->store_root_path))
>>>>>                 goto err;
>>>>> @@ -302,10 +303,17 @@ int semanage_direct_connect(semanage_handle_t * sh)
>>>>>
>>>>>         /* set the disable dontaudit value */
>>>>>         path = semanage_path(SEMANAGE_ACTIVE, SEMANAGE_DISABLE_DONTAUDIT);
>>>>> -       if (access(path, F_OK) == 0)
>>>>> +
>>>>> +       if (stat(path, &sb) == 0)
>>>>>                 sepol_set_disable_dontaudit(sh->sepolh, 1);
>>>>> -       else
>>>>> +       else {
>>>>> +               if (errno != ENOENT) {
>>>>> +                       ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
>>>>> +                       goto err;
>>>>> +               }
>>>>> +
>>>>>                 sepol_set_disable_dontaudit(sh->sepolh, 0);
>>>>> +       }
>>>>>
>>>>>         return STATUS_SUCCESS;
>>>>>
>>>>> @@ -1139,6 +1147,7 @@ static int semanage_compile_hll_modules(semanage_handle_t *sh,
>>>>>         int status = 0;
>>>>>         int i;
>>>>>         char cil_path[PATH_MAX];
>>>>> +       struct stat sb;
>>>>>
>>>>>         assert(sh);
>>>>>         assert(modinfos);
>>>>> @@ -1155,9 +1164,13 @@ static int semanage_compile_hll_modules(semanage_handle_t *sh,
>>>>>                 }
>>>>>
>>>>>                 if (semanage_get_ignore_module_cache(sh) == 0 &&
>>>>> -                               access(cil_path, F_OK) == 0) {
>>>>> +                               (status = stat(cil_path, &sb)) == 0) {
>>>>>                         continue;
>>>>>                 }
>>>>> +               if (status != 0 && errno != ENOENT) {
>>>>> +                       ERR(sh, "Unable to access %s: %s\n", cil_path, strerror(errno));
>>>>> +                       goto cleanup; //an error in the "stat" call
>>>>> +               }
>>>>>
>>>>>                 status = semanage_compile_module(sh, &modinfos[i]);
>>>>>                 if (status < 0) {
>>>>> @@ -1188,6 +1201,7 @@ static int semanage_direct_commit(semanage_handle_t * sh)
>>>>>         struct cil_db *cildb = NULL;
>>>>>         semanage_module_info_t *modinfos = NULL;
>>>>>         mode_t mask = umask(0077);
>>>>> +       struct stat sb;
>>>>>
>>>>>         int do_rebuild, do_write_kernel, do_install;
>>>>>         int fcontexts_modified, ports_modified, seusers_modified,
>>>>> @@ -1226,10 +1240,16 @@ static int semanage_direct_commit(semanage_handle_t * sh)
>>>>>
>>>>>         /* Create or remove the disable_dontaudit flag file. */
>>>>>         path = semanage_path(SEMANAGE_TMP, SEMANAGE_DISABLE_DONTAUDIT);
>>>>> -       if (access(path, F_OK) == 0)
>>>>> +       if (stat(path, &sb) == 0)
>>>>>                 do_rebuild |= !(sepol_get_disable_dontaudit(sh->sepolh) == 1);
>>>>> -       else
>>>>> +       else {
>>>>> +               if (errno != ENOENT) {
>>>>> +                       ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
>>>>> +                       goto cleanup;
>>>>> +               }
>>>>> +
>>>>
>>>> I am not a huge fan of this if under else block of if (errno !=ENOENT).
>>>>
>>>> maybe this is a bit cleaner:
>>>>
>>>> if (stat() == 0)
>>>>   //exists
>>>> else if (errno == ENOENT)
>>>>   // doesn't exist
>>>> else
>>>>   //fail
>>>>
>>>>>                 do_rebuild |= (sepol_get_disable_dontaudit(sh->sepolh) == 1);
>>>>> +       }
>>>>>         if (sepol_get_disable_dontaudit(sh->sepolh) == 1) {
>>>>>                 FILE *touch;
>>>>>                 touch = fopen(path, "w");
>>>>> @@ -1251,10 +1271,17 @@ static int semanage_direct_commit(semanage_handle_t * sh)
>>>>>
>>>>>         /* Create or remove the preserve_tunables flag file. */
>>>>>         path = semanage_path(SEMANAGE_TMP, SEMANAGE_PRESERVE_TUNABLES);
>>>>> -       if (access(path, F_OK) == 0)
>>>>> +       if (stat(path, &sb) == 0)
>>>>>                 do_rebuild |= !(sepol_get_preserve_tunables(sh->sepolh) == 1);
>>>>> -       else
>>>>> +       else {
>>>>> +               if (errno != ENOENT) {
>>>>> +                       ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
>>>>> +                       goto cleanup;
>>>>> +               }
>>>>> +
>>>>>                 do_rebuild |= (sepol_get_preserve_tunables(sh->sepolh) == 1);
>>>>> +       }
>>>>> +
>>>>>         if (sepol_get_preserve_tunables(sh->sepolh) == 1) {
>>>>>                 FILE *touch;
>>>>>                 touch = fopen(path, "w");
>>>>> @@ -1291,40 +1318,24 @@ static int semanage_direct_commit(semanage_handle_t * sh)
>>>>>          * a rebuild.
>>>>>          */
>>>>>         if (!do_rebuild) {
>>>>> -               path = semanage_path(SEMANAGE_TMP, SEMANAGE_STORE_KERNEL);
>>>>> -               if (access(path, F_OK) != 0) {
>>>>> -                       do_rebuild = 1;
>>>>> -                       goto rebuild;
>>>>> -               }
>>>>> -
>>>>> -               path = semanage_path(SEMANAGE_TMP, SEMANAGE_STORE_FC);
>>>>> -               if (access(path, F_OK) != 0) {
>>>>> -                       do_rebuild = 1;
>>>>> -                       goto rebuild;
>>>>> -               }
>>>>> -
>>>>> -               path = semanage_path(SEMANAGE_TMP, SEMANAGE_STORE_SEUSERS);
>>>>> -               if (access(path, F_OK) != 0) {
>>>>> -                       do_rebuild = 1;
>>>>> -                       goto rebuild;
>>>>> -               }
>>>>> -
>>>>> -               path = semanage_path(SEMANAGE_TMP, SEMANAGE_LINKED);
>>>>> -               if (access(path, F_OK) != 0) {
>>>>> -                       do_rebuild = 1;
>>>>> -                       goto rebuild;
>>>>> -               }
>>>>> -
>>>>> -               path = semanage_path(SEMANAGE_TMP, SEMANAGE_SEUSERS_LINKED);
>>>>> -               if (access(path, F_OK) != 0) {
>>>>> -                       do_rebuild = 1;
>>>>> -                       goto rebuild;
>>>>> -               }
>>>>> +               int files[] = {SEMANAGE_STORE_KERNEL,
>>>>> +                                          SEMANAGE_STORE_FC,
>>>>> +                                          SEMANAGE_STORE_SEUSERS,
>>>>> +                                          SEMANAGE_LINKED,
>>>>> +                                          SEMANAGE_SEUSERS_LINKED,
>>>>> +                                          SEMANAGE_USERS_EXTRA_LINKED};
>>>>> +
>>>>> +               for (i = 0; i < (int) sizeof(files); i++) {
>>>>> +                       path = semanage_path(SEMANAGE_TMP, files[i]);
>>>>> +                       if (stat(path, &sb) != 0) {
>>>>> +                               if (errno != ENOENT) {
>>>>> +                                       ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
>>>>> +                                       goto cleanup;
>>>>> +                               }
>>>>>
>>>>> -               path = semanage_path(SEMANAGE_TMP, SEMANAGE_USERS_EXTRA_LINKED);
>>>>> -               if (access(path, F_OK) != 0) {
>>>>> -                       do_rebuild = 1;
>>>>> -                       goto rebuild;
>>>>> +                               do_rebuild = 1;
>>>>> +                               goto rebuild;
>>>>> +                       }
>>>>>                 }
>>>>>         }
>>>>>
>>>>> @@ -1457,7 +1468,7 @@ rebuild:
>>>>>                         goto cleanup;
>>>>>
>>>>>                 path = semanage_path(SEMANAGE_TMP, SEMANAGE_SEUSERS_LINKED);
>>>>> -               if (access(path, F_OK) == 0) {
>>>>> +               if (stat(path, &sb) == 0) {
>>>>>                         retval = semanage_copy_file(path,
>>>>>                                                     semanage_path(SEMANAGE_TMP,
>>>>>                                                                   SEMANAGE_STORE_SEUSERS),
>>>>> @@ -1466,11 +1477,16 @@ rebuild:
>>>>>                                 goto cleanup;
>>>>>                         pseusers->dtable->drop_cache(pseusers->dbase);
>>>>>                 } else {
>>>>> +                       if (errno != ENOENT) {
>>>>> +                               ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
>>>>> +                               goto cleanup;
>>>>> +                       }
>>>>> +
>>>>>                         pseusers->dtable->clear(sh, pseusers->dbase);
>>>>>                 }
>>>>>
>>>>>                 path = semanage_path(SEMANAGE_TMP, SEMANAGE_USERS_EXTRA_LINKED);
>>>>> -               if (access(path, F_OK) == 0) {
>>>>> +               if (stat(path, &sb) == 0) {
>>>>>                         retval = semanage_copy_file(path,
>>>>>                                                     semanage_path(SEMANAGE_TMP,
>>>>>                                                                   SEMANAGE_USERS_EXTRA),
>>>>> @@ -1479,6 +1495,11 @@ rebuild:
>>>>>                                 goto cleanup;
>>>>>                         pusers_extra->dtable->drop_cache(pusers_extra->dbase);
>>>>>                 } else {
>>>>> +                       if (errno != ENOENT) {
>>>>> +                               ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
>>>>> +                               goto cleanup;
>>>>> +                       }
>>>>> +
>>>>>                         pusers_extra->dtable->clear(sh, pusers_extra->dbase);
>>>>>                 }
>>>>>         }
>>>>> @@ -1809,6 +1830,7 @@ static int semanage_direct_extract(semanage_handle_t * sh,
>>>>>         ssize_t _data_len;
>>>>>         char *_data;
>>>>>         int compressed;
>>>>> +       struct stat sb;
>>>>>
>>>>>         /* get path of module */
>>>>>         rc = semanage_module_get_path(
>>>>> @@ -1821,8 +1843,8 @@ static int semanage_direct_extract(semanage_handle_t * sh,
>>>>>                 goto cleanup;
>>>>>         }
>>>>>
>>>>> -       if (access(module_path, F_OK) != 0) {
>>>>> -               ERR(sh, "Module does not exist: %s", module_path);
>>>>> +       if (stat(module_path, &sb) != 0) {
>>>>> +               ERR(sh, "Unable to access %s: %s\n", module_path, strerror(errno));
>>>>>                 rc = -1;
>>>>>                 goto cleanup;
>>>>>         }
>>>>> @@ -1851,7 +1873,12 @@ static int semanage_direct_extract(semanage_handle_t * sh,
>>>>>                 goto cleanup;
>>>>>         }
>>>>>
>>>>> -       if (extract_cil == 1 && strcmp(_modinfo->lang_ext, "cil") && access(input_file, F_OK) != 0) {
>>>>> +       if (extract_cil == 1 && strcmp(_modinfo->lang_ext, "cil") && stat(input_file, &sb) != 0) {
>>>>> +               if (errno != ENOENT) {
>>>>> +                       ERR(sh, "Unable to access %s: %s\n", input_file, strerror(errno));
>>>>> +                       goto cleanup;
>>>>> +               }
>>>>> +
>>>>>                 rc = semanage_compile_module(sh, _modinfo);
>>>>>                 if (rc < 0) {
>>>>>                         goto cleanup;
>>>>> @@ -1996,6 +2023,12 @@ static int semanage_direct_get_enabled(semanage_handle_t *sh,
>>>>>         }
>>>>>
>>>>>         if (stat(path, &sb) < 0) {
>>>>> +               if (errno != ENOENT) {
>>>>> +                       ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
>>>>> +                       status = -1;
>>>>> +                       goto cleanup;
>>>>> +               }
>>>>> +
>>>>>                 *enabled = 1;
>>>>>         }
>>>>>         else {
>>>>> @@ -2322,6 +2355,12 @@ static int semanage_direct_get_module_info(semanage_handle_t *sh,
>>>>>
>>>>>         /* set enabled/disabled status */
>>>>>         if (stat(fn, &sb) < 0) {
>>>>> +               if (errno != ENOENT) {
>>>>> +                       ERR(sh, "Unable to access %s: %s\n", fn, strerror(errno));
>>>>> +                       status = -1;
>>>>> +                       goto cleanup;
>>>>> +               }
>>>>> +
>>>>>                 ret = semanage_module_info_set_enabled(sh, *modinfo, 1);
>>>>>                 if (ret != 0) {
>>>>>                         status = -1;
>>>>> @@ -2730,6 +2769,7 @@ static int semanage_direct_install_info(semanage_handle_t *sh,
>>>>>         int status = 0;
>>>>>         int ret = 0;
>>>>>         int type;
>>>>> +       struct stat sb;
>>>>>
>>>>>         char path[PATH_MAX];
>>>>>         mode_t mask = umask(0077);
>>>>> @@ -2830,7 +2870,7 @@ static int semanage_direct_install_info(semanage_handle_t *sh,
>>>>>                         goto cleanup;
>>>>>                 }
>>>>>
>>>>> -               if (access(path, F_OK) == 0) {
>>>>> +               if (stat(path, &sb) == 0) {
>>>>>                         ret = unlink(path);
>>>>>                         if (ret != 0) {
>>>>>                                 ERR(sh, "Error while removing cached CIL file %s: %s", path, strerror(errno));
>>>>> diff --git a/libsemanage/src/semanage_store.c b/libsemanage/src/semanage_store.c
>>>>> index 4bd1d651..83c188dc 100644
>>>>> --- a/libsemanage/src/semanage_store.c
>>>>> +++ b/libsemanage/src/semanage_store.c
>>>>> @@ -514,6 +514,7 @@ char *semanage_conf_path(void)
>>>>>  {
>>>>>         char *semanage_conf = NULL;
>>>>>         int len;
>>>>> +       FILE *fp = NULL;
>>>>>
>>>>>         len = strlen(semanage_root()) + strlen(selinux_path()) + strlen(SEMANAGE_CONF_FILE);
>>>>>         semanage_conf = calloc(len + 1, sizeof(char));
>>>>> @@ -522,7 +523,10 @@ char *semanage_conf_path(void)
>>>>>         snprintf(semanage_conf, len + 1, "%s%s%s", semanage_root(), selinux_path(),
>>>>>                  SEMANAGE_CONF_FILE);
>>>>>
>>>>> -       if (access(semanage_conf, R_OK) != 0) {
>>>>> +       //the following replaces access(semanage_conf, R_OK) check
>>>>> +       if ((fp = fopen(semanage_conf, "r")) != NULL) {
>>>>> +               fclose(fp);
>>>>> +       } else {
>>>>>                 snprintf(semanage_conf, len + 1, "%s%s", selinux_path(), SEMANAGE_CONF_FILE);
>>>>>         }
>>>>>
>>>>> @@ -1508,8 +1512,14 @@ int semanage_split_fc(semanage_handle_t * sh)
>>>>>  static int sefcontext_compile(semanage_handle_t * sh, const char *path) {
>>>>>
>>>>>         int r;
>>>>> +       struct stat sb;
>>>>> +
>>>>> +       if (stat(path, &sb) < 0) {
>>>>> +               if (errno != ENOENT) {
>>>>> +                       ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
>>>>> +                       return -1;
>>>>> +               }
>>>>>
>>>>> -       if (access(path, F_OK) != 0) {
>>>>>                 return 0;
>>>>>         }
>>>>>
>>>>> --
>>>>> 2.14.3
>>>>>
>>>>>



-- 
Respectfully,

William C Roberts

Re: Re: [PATCH 3/3] libsemanage: replace access() checks to make setuid programs work

[Stephen Smalley]

On 02/28/2018 02:26 PM, William Roberts wrote:
> So peeking through the code base, I see:
> 
> int semanage_direct_is_managed(semanage_handle_t * sh)
> {
> if (semanage_check_init(sh, sh->conf->store_root_path))
> goto err;
> 
> if (semanage_access_check(sh) < 0)
> return 0;
> 
> return 1;
> 
>       err:
> ERR(sh, "could not check whether policy is managed");
> return STATUS_ERR;
> }
> 
> Which semanage_access_check eventually gets down to a raw access check.
> 
> Which is only ever used in test_fcontext
> 
> semanage_access_check is also the only consumer of semanage_direct_access_check
> 
> which is the semanage_store_access_check is only consumed by the
> former and test case and
> the same could be said for semanage_store_access_check
> 
> I think this is a good time to roll in patch 4 and drop everything
> relying on semanage_store_access_check.
> 
> Thoughts?

semanage_access_check() is part of the shared library ABI. Can't be
removed.  Used by seobject.py via the python bindings.  At most, we can
kill all internal users but the ABI has to remain.

> 
> On Wed, Feb 28, 2018 at 11:07 AM, William Roberts
> <bill.c.roberts@gmail.com> wrote:
>> On Wed, Feb 28, 2018 at 10:43 AM, Stephen Smalley <sds@tycho.nsa.gov> wrote:
>>> On 02/28/2018 01:24 PM, William Roberts wrote:
>>>> Where is patch 2/2, I have yet to see it?
>>>>
>>>> Did something get screwy and is it: [PATCH] libsemanage: Improve
>>>> warning for installing disabled module
>>>
>>> No, 2/3 was a separate patch and had the 2/3 in the subject line.
>>> I received all three from the list, both locally and on my gmail.
>>>
>>
>> Thanks gmail for folding the patch 1/3 and 2/3 into the same "conversation" or
>> whatever it does.
>>
>>
>>>>
>>>>
>>>> On Wed, Feb 28, 2018 at 9:50 AM, William Roberts
>>>> <bill.c.roberts@gmail.com> wrote:
>>>>> On Wed, Feb 28, 2018 at 2:15 AM, Vit Mojzis <vmojzis@redhat.com> wrote:
>>>>>> access() uses real UID instead of effective UID which causes false
>>>>>> negative checks in setuid programs.
>>>>>> Replace access(,F_OK) (i.e. tests for file existence) by stat().
>>>>>> And access(,R_OK) by fopen(,"r")
>>>>>>
>>>>>> Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1186431
>>>>>>
>>>>>> Signed-off-by: Vit Mojzis <vmojzis@redhat.com>
>>>>>> ---
>>>>>>  libsemanage/src/direct_api.c     | 132 +++++++++++++++++++++++++--------------
>>>>>>  libsemanage/src/semanage_store.c |  14 ++++-
>>>>>>  2 files changed, 98 insertions(+), 48 deletions(-)
>>>>>>
>>>>>> diff --git a/libsemanage/src/direct_api.c b/libsemanage/src/direct_api.c
>>>>>> index f4d57cf8..d42a51cd 100644
>>>>>> --- a/libsemanage/src/direct_api.c
>>>>>> +++ b/libsemanage/src/direct_api.c
>>>>>> @@ -140,6 +140,7 @@ int semanage_direct_is_managed(semanage_handle_t * sh)
>>>>>>  int semanage_direct_connect(semanage_handle_t * sh)
>>>>>>  {
>>>>>>         const char *path;
>>>>>> +       struct stat sb;
>>>>>>
>>>>>>         if (semanage_check_init(sh, sh->conf->store_root_path))
>>>>>>                 goto err;
>>>>>> @@ -302,10 +303,17 @@ int semanage_direct_connect(semanage_handle_t * sh)
>>>>>>
>>>>>>         /* set the disable dontaudit value */
>>>>>>         path = semanage_path(SEMANAGE_ACTIVE, SEMANAGE_DISABLE_DONTAUDIT);
>>>>>> -       if (access(path, F_OK) == 0)
>>>>>> +
>>>>>> +       if (stat(path, &sb) == 0)
>>>>>>                 sepol_set_disable_dontaudit(sh->sepolh, 1);
>>>>>> -       else
>>>>>> +       else {
>>>>>> +               if (errno != ENOENT) {
>>>>>> +                       ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
>>>>>> +                       goto err;
>>>>>> +               }
>>>>>> +
>>>>>>                 sepol_set_disable_dontaudit(sh->sepolh, 0);
>>>>>> +       }
>>>>>>
>>>>>>         return STATUS_SUCCESS;
>>>>>>
>>>>>> @@ -1139,6 +1147,7 @@ static int semanage_compile_hll_modules(semanage_handle_t *sh,
>>>>>>         int status = 0;
>>>>>>         int i;
>>>>>>         char cil_path[PATH_MAX];
>>>>>> +       struct stat sb;
>>>>>>
>>>>>>         assert(sh);
>>>>>>         assert(modinfos);
>>>>>> @@ -1155,9 +1164,13 @@ static int semanage_compile_hll_modules(semanage_handle_t *sh,
>>>>>>                 }
>>>>>>
>>>>>>                 if (semanage_get_ignore_module_cache(sh) == 0 &&
>>>>>> -                               access(cil_path, F_OK) == 0) {
>>>>>> +                               (status = stat(cil_path, &sb)) == 0) {
>>>>>>                         continue;
>>>>>>                 }
>>>>>> +               if (status != 0 && errno != ENOENT) {
>>>>>> +                       ERR(sh, "Unable to access %s: %s\n", cil_path, strerror(errno));
>>>>>> +                       goto cleanup; //an error in the "stat" call
>>>>>> +               }
>>>>>>
>>>>>>                 status = semanage_compile_module(sh, &modinfos[i]);
>>>>>>                 if (status < 0) {
>>>>>> @@ -1188,6 +1201,7 @@ static int semanage_direct_commit(semanage_handle_t * sh)
>>>>>>         struct cil_db *cildb = NULL;
>>>>>>         semanage_module_info_t *modinfos = NULL;
>>>>>>         mode_t mask = umask(0077);
>>>>>> +       struct stat sb;
>>>>>>
>>>>>>         int do_rebuild, do_write_kernel, do_install;
>>>>>>         int fcontexts_modified, ports_modified, seusers_modified,
>>>>>> @@ -1226,10 +1240,16 @@ static int semanage_direct_commit(semanage_handle_t * sh)
>>>>>>
>>>>>>         /* Create or remove the disable_dontaudit flag file. */
>>>>>>         path = semanage_path(SEMANAGE_TMP, SEMANAGE_DISABLE_DONTAUDIT);
>>>>>> -       if (access(path, F_OK) == 0)
>>>>>> +       if (stat(path, &sb) == 0)
>>>>>>                 do_rebuild |= !(sepol_get_disable_dontaudit(sh->sepolh) == 1);
>>>>>> -       else
>>>>>> +       else {
>>>>>> +               if (errno != ENOENT) {
>>>>>> +                       ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
>>>>>> +                       goto cleanup;
>>>>>> +               }
>>>>>> +
>>>>>
>>>>> I am not a huge fan of this if under else block of if (errno !=ENOENT).
>>>>>
>>>>> maybe this is a bit cleaner:
>>>>>
>>>>> if (stat() == 0)
>>>>>   //exists
>>>>> else if (errno == ENOENT)
>>>>>   // doesn't exist
>>>>> else
>>>>>   //fail
>>>>>
>>>>>>                 do_rebuild |= (sepol_get_disable_dontaudit(sh->sepolh) == 1);
>>>>>> +       }
>>>>>>         if (sepol_get_disable_dontaudit(sh->sepolh) == 1) {
>>>>>>                 FILE *touch;
>>>>>>                 touch = fopen(path, "w");
>>>>>> @@ -1251,10 +1271,17 @@ static int semanage_direct_commit(semanage_handle_t * sh)
>>>>>>
>>>>>>         /* Create or remove the preserve_tunables flag file. */
>>>>>>         path = semanage_path(SEMANAGE_TMP, SEMANAGE_PRESERVE_TUNABLES);
>>>>>> -       if (access(path, F_OK) == 0)
>>>>>> +       if (stat(path, &sb) == 0)
>>>>>>                 do_rebuild |= !(sepol_get_preserve_tunables(sh->sepolh) == 1);
>>>>>> -       else
>>>>>> +       else {
>>>>>> +               if (errno != ENOENT) {
>>>>>> +                       ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
>>>>>> +                       goto cleanup;
>>>>>> +               }
>>>>>> +
>>>>>>                 do_rebuild |= (sepol_get_preserve_tunables(sh->sepolh) == 1);
>>>>>> +       }
>>>>>> +
>>>>>>         if (sepol_get_preserve_tunables(sh->sepolh) == 1) {
>>>>>>                 FILE *touch;
>>>>>>                 touch = fopen(path, "w");
>>>>>> @@ -1291,40 +1318,24 @@ static int semanage_direct_commit(semanage_handle_t * sh)
>>>>>>          * a rebuild.
>>>>>>          */
>>>>>>         if (!do_rebuild) {
>>>>>> -               path = semanage_path(SEMANAGE_TMP, SEMANAGE_STORE_KERNEL);
>>>>>> -               if (access(path, F_OK) != 0) {
>>>>>> -                       do_rebuild = 1;
>>>>>> -                       goto rebuild;
>>>>>> -               }
>>>>>> -
>>>>>> -               path = semanage_path(SEMANAGE_TMP, SEMANAGE_STORE_FC);
>>>>>> -               if (access(path, F_OK) != 0) {
>>>>>> -                       do_rebuild = 1;
>>>>>> -                       goto rebuild;
>>>>>> -               }
>>>>>> -
>>>>>> -               path = semanage_path(SEMANAGE_TMP, SEMANAGE_STORE_SEUSERS);
>>>>>> -               if (access(path, F_OK) != 0) {
>>>>>> -                       do_rebuild = 1;
>>>>>> -                       goto rebuild;
>>>>>> -               }
>>>>>> -
>>>>>> -               path = semanage_path(SEMANAGE_TMP, SEMANAGE_LINKED);
>>>>>> -               if (access(path, F_OK) != 0) {
>>>>>> -                       do_rebuild = 1;
>>>>>> -                       goto rebuild;
>>>>>> -               }
>>>>>> -
>>>>>> -               path = semanage_path(SEMANAGE_TMP, SEMANAGE_SEUSERS_LINKED);
>>>>>> -               if (access(path, F_OK) != 0) {
>>>>>> -                       do_rebuild = 1;
>>>>>> -                       goto rebuild;
>>>>>> -               }
>>>>>> +               int files[] = {SEMANAGE_STORE_KERNEL,
>>>>>> +                                          SEMANAGE_STORE_FC,
>>>>>> +                                          SEMANAGE_STORE_SEUSERS,
>>>>>> +                                          SEMANAGE_LINKED,
>>>>>> +                                          SEMANAGE_SEUSERS_LINKED,
>>>>>> +                                          SEMANAGE_USERS_EXTRA_LINKED};
>>>>>> +
>>>>>> +               for (i = 0; i < (int) sizeof(files); i++) {
>>>>>> +                       path = semanage_path(SEMANAGE_TMP, files[i]);
>>>>>> +                       if (stat(path, &sb) != 0) {
>>>>>> +                               if (errno != ENOENT) {
>>>>>> +                                       ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
>>>>>> +                                       goto cleanup;
>>>>>> +                               }
>>>>>>
>>>>>> -               path = semanage_path(SEMANAGE_TMP, SEMANAGE_USERS_EXTRA_LINKED);
>>>>>> -               if (access(path, F_OK) != 0) {
>>>>>> -                       do_rebuild = 1;
>>>>>> -                       goto rebuild;
>>>>>> +                               do_rebuild = 1;
>>>>>> +                               goto rebuild;
>>>>>> +                       }
>>>>>>                 }
>>>>>>         }
>>>>>>
>>>>>> @@ -1457,7 +1468,7 @@ rebuild:
>>>>>>                         goto cleanup;
>>>>>>
>>>>>>                 path = semanage_path(SEMANAGE_TMP, SEMANAGE_SEUSERS_LINKED);
>>>>>> -               if (access(path, F_OK) == 0) {
>>>>>> +               if (stat(path, &sb) == 0) {
>>>>>>                         retval = semanage_copy_file(path,
>>>>>>                                                     semanage_path(SEMANAGE_TMP,
>>>>>>                                                                   SEMANAGE_STORE_SEUSERS),
>>>>>> @@ -1466,11 +1477,16 @@ rebuild:
>>>>>>                                 goto cleanup;
>>>>>>                         pseusers->dtable->drop_cache(pseusers->dbase);
>>>>>>                 } else {
>>>>>> +                       if (errno != ENOENT) {
>>>>>> +                               ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
>>>>>> +                               goto cleanup;
>>>>>> +                       }
>>>>>> +
>>>>>>                         pseusers->dtable->clear(sh, pseusers->dbase);
>>>>>>                 }
>>>>>>
>>>>>>                 path = semanage_path(SEMANAGE_TMP, SEMANAGE_USERS_EXTRA_LINKED);
>>>>>> -               if (access(path, F_OK) == 0) {
>>>>>> +               if (stat(path, &sb) == 0) {
>>>>>>                         retval = semanage_copy_file(path,
>>>>>>                                                     semanage_path(SEMANAGE_TMP,
>>>>>>                                                                   SEMANAGE_USERS_EXTRA),
>>>>>> @@ -1479,6 +1495,11 @@ rebuild:
>>>>>>                                 goto cleanup;
>>>>>>                         pusers_extra->dtable->drop_cache(pusers_extra->dbase);
>>>>>>                 } else {
>>>>>> +                       if (errno != ENOENT) {
>>>>>> +                               ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
>>>>>> +                               goto cleanup;
>>>>>> +                       }
>>>>>> +
>>>>>>                         pusers_extra->dtable->clear(sh, pusers_extra->dbase);
>>>>>>                 }
>>>>>>         }
>>>>>> @@ -1809,6 +1830,7 @@ static int semanage_direct_extract(semanage_handle_t * sh,
>>>>>>         ssize_t _data_len;
>>>>>>         char *_data;
>>>>>>         int compressed;
>>>>>> +       struct stat sb;
>>>>>>
>>>>>>         /* get path of module */
>>>>>>         rc = semanage_module_get_path(
>>>>>> @@ -1821,8 +1843,8 @@ static int semanage_direct_extract(semanage_handle_t * sh,
>>>>>>                 goto cleanup;
>>>>>>         }
>>>>>>
>>>>>> -       if (access(module_path, F_OK) != 0) {
>>>>>> -               ERR(sh, "Module does not exist: %s", module_path);
>>>>>> +       if (stat(module_path, &sb) != 0) {
>>>>>> +               ERR(sh, "Unable to access %s: %s\n", module_path, strerror(errno));
>>>>>>                 rc = -1;
>>>>>>                 goto cleanup;
>>>>>>         }
>>>>>> @@ -1851,7 +1873,12 @@ static int semanage_direct_extract(semanage_handle_t * sh,
>>>>>>                 goto cleanup;
>>>>>>         }
>>>>>>
>>>>>> -       if (extract_cil == 1 && strcmp(_modinfo->lang_ext, "cil") && access(input_file, F_OK) != 0) {
>>>>>> +       if (extract_cil == 1 && strcmp(_modinfo->lang_ext, "cil") && stat(input_file, &sb) != 0) {
>>>>>> +               if (errno != ENOENT) {
>>>>>> +                       ERR(sh, "Unable to access %s: %s\n", input_file, strerror(errno));
>>>>>> +                       goto cleanup;
>>>>>> +               }
>>>>>> +
>>>>>>                 rc = semanage_compile_module(sh, _modinfo);
>>>>>>                 if (rc < 0) {
>>>>>>                         goto cleanup;
>>>>>> @@ -1996,6 +2023,12 @@ static int semanage_direct_get_enabled(semanage_handle_t *sh,
>>>>>>         }
>>>>>>
>>>>>>         if (stat(path, &sb) < 0) {
>>>>>> +               if (errno != ENOENT) {
>>>>>> +                       ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
>>>>>> +                       status = -1;
>>>>>> +                       goto cleanup;
>>>>>> +               }
>>>>>> +
>>>>>>                 *enabled = 1;
>>>>>>         }
>>>>>>         else {
>>>>>> @@ -2322,6 +2355,12 @@ static int semanage_direct_get_module_info(semanage_handle_t *sh,
>>>>>>
>>>>>>         /* set enabled/disabled status */
>>>>>>         if (stat(fn, &sb) < 0) {
>>>>>> +               if (errno != ENOENT) {
>>>>>> +                       ERR(sh, "Unable to access %s: %s\n", fn, strerror(errno));
>>>>>> +                       status = -1;
>>>>>> +                       goto cleanup;
>>>>>> +               }
>>>>>> +
>>>>>>                 ret = semanage_module_info_set_enabled(sh, *modinfo, 1);
>>>>>>                 if (ret != 0) {
>>>>>>                         status = -1;
>>>>>> @@ -2730,6 +2769,7 @@ static int semanage_direct_install_info(semanage_handle_t *sh,
>>>>>>         int status = 0;
>>>>>>         int ret = 0;
>>>>>>         int type;
>>>>>> +       struct stat sb;
>>>>>>
>>>>>>         char path[PATH_MAX];
>>>>>>         mode_t mask = umask(0077);
>>>>>> @@ -2830,7 +2870,7 @@ static int semanage_direct_install_info(semanage_handle_t *sh,
>>>>>>                         goto cleanup;
>>>>>>                 }
>>>>>>
>>>>>> -               if (access(path, F_OK) == 0) {
>>>>>> +               if (stat(path, &sb) == 0) {
>>>>>>                         ret = unlink(path);
>>>>>>                         if (ret != 0) {
>>>>>>                                 ERR(sh, "Error while removing cached CIL file %s: %s", path, strerror(errno));
>>>>>> diff --git a/libsemanage/src/semanage_store.c b/libsemanage/src/semanage_store.c
>>>>>> index 4bd1d651..83c188dc 100644
>>>>>> --- a/libsemanage/src/semanage_store.c
>>>>>> +++ b/libsemanage/src/semanage_store.c
>>>>>> @@ -514,6 +514,7 @@ char *semanage_conf_path(void)
>>>>>>  {
>>>>>>         char *semanage_conf = NULL;
>>>>>>         int len;
>>>>>> +       FILE *fp = NULL;
>>>>>>
>>>>>>         len = strlen(semanage_root()) + strlen(selinux_path()) + strlen(SEMANAGE_CONF_FILE);
>>>>>>         semanage_conf = calloc(len + 1, sizeof(char));
>>>>>> @@ -522,7 +523,10 @@ char *semanage_conf_path(void)
>>>>>>         snprintf(semanage_conf, len + 1, "%s%s%s", semanage_root(), selinux_path(),
>>>>>>                  SEMANAGE_CONF_FILE);
>>>>>>
>>>>>> -       if (access(semanage_conf, R_OK) != 0) {
>>>>>> +       //the following replaces access(semanage_conf, R_OK) check
>>>>>> +       if ((fp = fopen(semanage_conf, "r")) != NULL) {
>>>>>> +               fclose(fp);
>>>>>> +       } else {
>>>>>>                 snprintf(semanage_conf, len + 1, "%s%s", selinux_path(), SEMANAGE_CONF_FILE);
>>>>>>         }
>>>>>>
>>>>>> @@ -1508,8 +1512,14 @@ int semanage_split_fc(semanage_handle_t * sh)
>>>>>>  static int sefcontext_compile(semanage_handle_t * sh, const char *path) {
>>>>>>
>>>>>>         int r;
>>>>>> +       struct stat sb;
>>>>>> +
>>>>>> +       if (stat(path, &sb) < 0) {
>>>>>> +               if (errno != ENOENT) {
>>>>>> +                       ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
>>>>>> +                       return -1;
>>>>>> +               }
>>>>>>
>>>>>> -       if (access(path, F_OK) != 0) {
>>>>>>                 return 0;
>>>>>>         }
>>>>>>
>>>>>> --
>>>>>> 2.14.3
>>>>>>
>>>>>>
> 
> 
> 

Re: Re: [PATCH 3/3] libsemanage: replace access() checks to make setuid programs work

[William Roberts]

On Wed, Feb 28, 2018 at 11:39 AM, Stephen Smalley <sds@tycho.nsa.gov> wrote:
> On 02/28/2018 02:26 PM, William Roberts wrote:
>> So peeking through the code base, I see:
>>
>> int semanage_direct_is_managed(semanage_handle_t * sh)
>> {
>> if (semanage_check_init(sh, sh->conf->store_root_path))
>> goto err;
>>
>> if (semanage_access_check(sh) < 0)
>> return 0;
>>
>> return 1;
>>
>>       err:
>> ERR(sh, "could not check whether policy is managed");
>> return STATUS_ERR;
>> }
>>
>> Which semanage_access_check eventually gets down to a raw access check.
>>
>> Which is only ever used in test_fcontext
>>
>> semanage_access_check is also the only consumer of semanage_direct_access_check
>>
>> which is the semanage_store_access_check is only consumed by the
>> former and test case and
>> the same could be said for semanage_store_access_check
>>
>> I think this is a good time to roll in patch 4 and drop everything
>> relying on semanage_store_access_check.
>>
>> Thoughts?
>
> semanage_access_check() is part of the shared library ABI. Can't be
> removed.  Used by seobject.py via the python bindings.  At most, we can
> kill all internal users but the ABI has to remain.

Ahh yes, duh.

Outside of just killing off internal users of it, should we modify it
to not use access?
So it at least works under setuid?

>
>>
>> On Wed, Feb 28, 2018 at 11:07 AM, William Roberts
>> <bill.c.roberts@gmail.com> wrote:
>>> On Wed, Feb 28, 2018 at 10:43 AM, Stephen Smalley <sds@tycho.nsa.gov> wrote:
>>>> On 02/28/2018 01:24 PM, William Roberts wrote:
>>>>> Where is patch 2/2, I have yet to see it?
>>>>>
>>>>> Did something get screwy and is it: [PATCH] libsemanage: Improve
>>>>> warning for installing disabled module
>>>>
>>>> No, 2/3 was a separate patch and had the 2/3 in the subject line.
>>>> I received all three from the list, both locally and on my gmail.
>>>>
>>>
>>> Thanks gmail for folding the patch 1/3 and 2/3 into the same "conversation" or
>>> whatever it does.
>>>
>>>
>>>>>
>>>>>
>>>>> On Wed, Feb 28, 2018 at 9:50 AM, William Roberts
>>>>> <bill.c.roberts@gmail.com> wrote:
>>>>>> On Wed, Feb 28, 2018 at 2:15 AM, Vit Mojzis <vmojzis@redhat.com> wrote:
>>>>>>> access() uses real UID instead of effective UID which causes false
>>>>>>> negative checks in setuid programs.
>>>>>>> Replace access(,F_OK) (i.e. tests for file existence) by stat().
>>>>>>> And access(,R_OK) by fopen(,"r")
>>>>>>>
>>>>>>> Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1186431
>>>>>>>
>>>>>>> Signed-off-by: Vit Mojzis <vmojzis@redhat.com>
>>>>>>> ---
>>>>>>>  libsemanage/src/direct_api.c     | 132 +++++++++++++++++++++++++--------------
>>>>>>>  libsemanage/src/semanage_store.c |  14 ++++-
>>>>>>>  2 files changed, 98 insertions(+), 48 deletions(-)
>>>>>>>
>>>>>>> diff --git a/libsemanage/src/direct_api.c b/libsemanage/src/direct_api.c
>>>>>>> index f4d57cf8..d42a51cd 100644
>>>>>>> --- a/libsemanage/src/direct_api.c
>>>>>>> +++ b/libsemanage/src/direct_api.c
>>>>>>> @@ -140,6 +140,7 @@ int semanage_direct_is_managed(semanage_handle_t * sh)
>>>>>>>  int semanage_direct_connect(semanage_handle_t * sh)
>>>>>>>  {
>>>>>>>         const char *path;
>>>>>>> +       struct stat sb;
>>>>>>>
>>>>>>>         if (semanage_check_init(sh, sh->conf->store_root_path))
>>>>>>>                 goto err;
>>>>>>> @@ -302,10 +303,17 @@ int semanage_direct_connect(semanage_handle_t * sh)
>>>>>>>
>>>>>>>         /* set the disable dontaudit value */
>>>>>>>         path = semanage_path(SEMANAGE_ACTIVE, SEMANAGE_DISABLE_DONTAUDIT);
>>>>>>> -       if (access(path, F_OK) == 0)
>>>>>>> +
>>>>>>> +       if (stat(path, &sb) == 0)
>>>>>>>                 sepol_set_disable_dontaudit(sh->sepolh, 1);
>>>>>>> -       else
>>>>>>> +       else {
>>>>>>> +               if (errno != ENOENT) {
>>>>>>> +                       ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
>>>>>>> +                       goto err;
>>>>>>> +               }
>>>>>>> +
>>>>>>>                 sepol_set_disable_dontaudit(sh->sepolh, 0);
>>>>>>> +       }
>>>>>>>
>>>>>>>         return STATUS_SUCCESS;
>>>>>>>
>>>>>>> @@ -1139,6 +1147,7 @@ static int semanage_compile_hll_modules(semanage_handle_t *sh,
>>>>>>>         int status = 0;
>>>>>>>         int i;
>>>>>>>         char cil_path[PATH_MAX];
>>>>>>> +       struct stat sb;
>>>>>>>
>>>>>>>         assert(sh);
>>>>>>>         assert(modinfos);
>>>>>>> @@ -1155,9 +1164,13 @@ static int semanage_compile_hll_modules(semanage_handle_t *sh,
>>>>>>>                 }
>>>>>>>
>>>>>>>                 if (semanage_get_ignore_module_cache(sh) == 0 &&
>>>>>>> -                               access(cil_path, F_OK) == 0) {
>>>>>>> +                               (status = stat(cil_path, &sb)) == 0) {
>>>>>>>                         continue;
>>>>>>>                 }
>>>>>>> +               if (status != 0 && errno != ENOENT) {
>>>>>>> +                       ERR(sh, "Unable to access %s: %s\n", cil_path, strerror(errno));
>>>>>>> +                       goto cleanup; //an error in the "stat" call
>>>>>>> +               }
>>>>>>>
>>>>>>>                 status = semanage_compile_module(sh, &modinfos[i]);
>>>>>>>                 if (status < 0) {
>>>>>>> @@ -1188,6 +1201,7 @@ static int semanage_direct_commit(semanage_handle_t * sh)
>>>>>>>         struct cil_db *cildb = NULL;
>>>>>>>         semanage_module_info_t *modinfos = NULL;
>>>>>>>         mode_t mask = umask(0077);
>>>>>>> +       struct stat sb;
>>>>>>>
>>>>>>>         int do_rebuild, do_write_kernel, do_install;
>>>>>>>         int fcontexts_modified, ports_modified, seusers_modified,
>>>>>>> @@ -1226,10 +1240,16 @@ static int semanage_direct_commit(semanage_handle_t * sh)
>>>>>>>
>>>>>>>         /* Create or remove the disable_dontaudit flag file. */
>>>>>>>         path = semanage_path(SEMANAGE_TMP, SEMANAGE_DISABLE_DONTAUDIT);
>>>>>>> -       if (access(path, F_OK) == 0)
>>>>>>> +       if (stat(path, &sb) == 0)
>>>>>>>                 do_rebuild |= !(sepol_get_disable_dontaudit(sh->sepolh) == 1);
>>>>>>> -       else
>>>>>>> +       else {
>>>>>>> +               if (errno != ENOENT) {
>>>>>>> +                       ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
>>>>>>> +                       goto cleanup;
>>>>>>> +               }
>>>>>>> +
>>>>>>
>>>>>> I am not a huge fan of this if under else block of if (errno !=ENOENT).
>>>>>>
>>>>>> maybe this is a bit cleaner:
>>>>>>
>>>>>> if (stat() == 0)
>>>>>>   //exists
>>>>>> else if (errno == ENOENT)
>>>>>>   // doesn't exist
>>>>>> else
>>>>>>   //fail
>>>>>>
>>>>>>>                 do_rebuild |= (sepol_get_disable_dontaudit(sh->sepolh) == 1);
>>>>>>> +       }
>>>>>>>         if (sepol_get_disable_dontaudit(sh->sepolh) == 1) {
>>>>>>>                 FILE *touch;
>>>>>>>                 touch = fopen(path, "w");
>>>>>>> @@ -1251,10 +1271,17 @@ static int semanage_direct_commit(semanage_handle_t * sh)
>>>>>>>
>>>>>>>         /* Create or remove the preserve_tunables flag file. */
>>>>>>>         path = semanage_path(SEMANAGE_TMP, SEMANAGE_PRESERVE_TUNABLES);
>>>>>>> -       if (access(path, F_OK) == 0)
>>>>>>> +       if (stat(path, &sb) == 0)
>>>>>>>                 do_rebuild |= !(sepol_get_preserve_tunables(sh->sepolh) == 1);
>>>>>>> -       else
>>>>>>> +       else {
>>>>>>> +               if (errno != ENOENT) {
>>>>>>> +                       ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
>>>>>>> +                       goto cleanup;
>>>>>>> +               }
>>>>>>> +
>>>>>>>                 do_rebuild |= (sepol_get_preserve_tunables(sh->sepolh) == 1);
>>>>>>> +       }
>>>>>>> +
>>>>>>>         if (sepol_get_preserve_tunables(sh->sepolh) == 1) {
>>>>>>>                 FILE *touch;
>>>>>>>                 touch = fopen(path, "w");
>>>>>>> @@ -1291,40 +1318,24 @@ static int semanage_direct_commit(semanage_handle_t * sh)
>>>>>>>          * a rebuild.
>>>>>>>          */
>>>>>>>         if (!do_rebuild) {
>>>>>>> -               path = semanage_path(SEMANAGE_TMP, SEMANAGE_STORE_KERNEL);
>>>>>>> -               if (access(path, F_OK) != 0) {
>>>>>>> -                       do_rebuild = 1;
>>>>>>> -                       goto rebuild;
>>>>>>> -               }
>>>>>>> -
>>>>>>> -               path = semanage_path(SEMANAGE_TMP, SEMANAGE_STORE_FC);
>>>>>>> -               if (access(path, F_OK) != 0) {
>>>>>>> -                       do_rebuild = 1;
>>>>>>> -                       goto rebuild;
>>>>>>> -               }
>>>>>>> -
>>>>>>> -               path = semanage_path(SEMANAGE_TMP, SEMANAGE_STORE_SEUSERS);
>>>>>>> -               if (access(path, F_OK) != 0) {
>>>>>>> -                       do_rebuild = 1;
>>>>>>> -                       goto rebuild;
>>>>>>> -               }
>>>>>>> -
>>>>>>> -               path = semanage_path(SEMANAGE_TMP, SEMANAGE_LINKED);
>>>>>>> -               if (access(path, F_OK) != 0) {
>>>>>>> -                       do_rebuild = 1;
>>>>>>> -                       goto rebuild;
>>>>>>> -               }
>>>>>>> -
>>>>>>> -               path = semanage_path(SEMANAGE_TMP, SEMANAGE_SEUSERS_LINKED);
>>>>>>> -               if (access(path, F_OK) != 0) {
>>>>>>> -                       do_rebuild = 1;
>>>>>>> -                       goto rebuild;
>>>>>>> -               }
>>>>>>> +               int files[] = {SEMANAGE_STORE_KERNEL,
>>>>>>> +                                          SEMANAGE_STORE_FC,
>>>>>>> +                                          SEMANAGE_STORE_SEUSERS,
>>>>>>> +                                          SEMANAGE_LINKED,
>>>>>>> +                                          SEMANAGE_SEUSERS_LINKED,
>>>>>>> +                                          SEMANAGE_USERS_EXTRA_LINKED};
>>>>>>> +
>>>>>>> +               for (i = 0; i < (int) sizeof(files); i++) {
>>>>>>> +                       path = semanage_path(SEMANAGE_TMP, files[i]);
>>>>>>> +                       if (stat(path, &sb) != 0) {
>>>>>>> +                               if (errno != ENOENT) {
>>>>>>> +                                       ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
>>>>>>> +                                       goto cleanup;
>>>>>>> +                               }
>>>>>>>
>>>>>>> -               path = semanage_path(SEMANAGE_TMP, SEMANAGE_USERS_EXTRA_LINKED);
>>>>>>> -               if (access(path, F_OK) != 0) {
>>>>>>> -                       do_rebuild = 1;
>>>>>>> -                       goto rebuild;
>>>>>>> +                               do_rebuild = 1;
>>>>>>> +                               goto rebuild;
>>>>>>> +                       }
>>>>>>>                 }
>>>>>>>         }
>>>>>>>
>>>>>>> @@ -1457,7 +1468,7 @@ rebuild:
>>>>>>>                         goto cleanup;
>>>>>>>
>>>>>>>                 path = semanage_path(SEMANAGE_TMP, SEMANAGE_SEUSERS_LINKED);
>>>>>>> -               if (access(path, F_OK) == 0) {
>>>>>>> +               if (stat(path, &sb) == 0) {
>>>>>>>                         retval = semanage_copy_file(path,
>>>>>>>                                                     semanage_path(SEMANAGE_TMP,
>>>>>>>                                                                   SEMANAGE_STORE_SEUSERS),
>>>>>>> @@ -1466,11 +1477,16 @@ rebuild:
>>>>>>>                                 goto cleanup;
>>>>>>>                         pseusers->dtable->drop_cache(pseusers->dbase);
>>>>>>>                 } else {
>>>>>>> +                       if (errno != ENOENT) {
>>>>>>> +                               ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
>>>>>>> +                               goto cleanup;
>>>>>>> +                       }
>>>>>>> +
>>>>>>>                         pseusers->dtable->clear(sh, pseusers->dbase);
>>>>>>>                 }
>>>>>>>
>>>>>>>                 path = semanage_path(SEMANAGE_TMP, SEMANAGE_USERS_EXTRA_LINKED);
>>>>>>> -               if (access(path, F_OK) == 0) {
>>>>>>> +               if (stat(path, &sb) == 0) {
>>>>>>>                         retval = semanage_copy_file(path,
>>>>>>>                                                     semanage_path(SEMANAGE_TMP,
>>>>>>>                                                                   SEMANAGE_USERS_EXTRA),
>>>>>>> @@ -1479,6 +1495,11 @@ rebuild:
>>>>>>>                                 goto cleanup;
>>>>>>>                         pusers_extra->dtable->drop_cache(pusers_extra->dbase);
>>>>>>>                 } else {
>>>>>>> +                       if (errno != ENOENT) {
>>>>>>> +                               ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
>>>>>>> +                               goto cleanup;
>>>>>>> +                       }
>>>>>>> +
>>>>>>>                         pusers_extra->dtable->clear(sh, pusers_extra->dbase);
>>>>>>>                 }
>>>>>>>         }
>>>>>>> @@ -1809,6 +1830,7 @@ static int semanage_direct_extract(semanage_handle_t * sh,
>>>>>>>         ssize_t _data_len;
>>>>>>>         char *_data;
>>>>>>>         int compressed;
>>>>>>> +       struct stat sb;
>>>>>>>
>>>>>>>         /* get path of module */
>>>>>>>         rc = semanage_module_get_path(
>>>>>>> @@ -1821,8 +1843,8 @@ static int semanage_direct_extract(semanage_handle_t * sh,
>>>>>>>                 goto cleanup;
>>>>>>>         }
>>>>>>>
>>>>>>> -       if (access(module_path, F_OK) != 0) {
>>>>>>> -               ERR(sh, "Module does not exist: %s", module_path);
>>>>>>> +       if (stat(module_path, &sb) != 0) {
>>>>>>> +               ERR(sh, "Unable to access %s: %s\n", module_path, strerror(errno));
>>>>>>>                 rc = -1;
>>>>>>>                 goto cleanup;
>>>>>>>         }
>>>>>>> @@ -1851,7 +1873,12 @@ static int semanage_direct_extract(semanage_handle_t * sh,
>>>>>>>                 goto cleanup;
>>>>>>>         }
>>>>>>>
>>>>>>> -       if (extract_cil == 1 && strcmp(_modinfo->lang_ext, "cil") && access(input_file, F_OK) != 0) {
>>>>>>> +       if (extract_cil == 1 && strcmp(_modinfo->lang_ext, "cil") && stat(input_file, &sb) != 0) {
>>>>>>> +               if (errno != ENOENT) {
>>>>>>> +                       ERR(sh, "Unable to access %s: %s\n", input_file, strerror(errno));
>>>>>>> +                       goto cleanup;
>>>>>>> +               }
>>>>>>> +
>>>>>>>                 rc = semanage_compile_module(sh, _modinfo);
>>>>>>>                 if (rc < 0) {
>>>>>>>                         goto cleanup;
>>>>>>> @@ -1996,6 +2023,12 @@ static int semanage_direct_get_enabled(semanage_handle_t *sh,
>>>>>>>         }
>>>>>>>
>>>>>>>         if (stat(path, &sb) < 0) {
>>>>>>> +               if (errno != ENOENT) {
>>>>>>> +                       ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
>>>>>>> +                       status = -1;
>>>>>>> +                       goto cleanup;
>>>>>>> +               }
>>>>>>> +
>>>>>>>                 *enabled = 1;
>>>>>>>         }
>>>>>>>         else {
>>>>>>> @@ -2322,6 +2355,12 @@ static int semanage_direct_get_module_info(semanage_handle_t *sh,
>>>>>>>
>>>>>>>         /* set enabled/disabled status */
>>>>>>>         if (stat(fn, &sb) < 0) {
>>>>>>> +               if (errno != ENOENT) {
>>>>>>> +                       ERR(sh, "Unable to access %s: %s\n", fn, strerror(errno));
>>>>>>> +                       status = -1;
>>>>>>> +                       goto cleanup;
>>>>>>> +               }
>>>>>>> +
>>>>>>>                 ret = semanage_module_info_set_enabled(sh, *modinfo, 1);
>>>>>>>                 if (ret != 0) {
>>>>>>>                         status = -1;
>>>>>>> @@ -2730,6 +2769,7 @@ static int semanage_direct_install_info(semanage_handle_t *sh,
>>>>>>>         int status = 0;
>>>>>>>         int ret = 0;
>>>>>>>         int type;
>>>>>>> +       struct stat sb;
>>>>>>>
>>>>>>>         char path[PATH_MAX];
>>>>>>>         mode_t mask = umask(0077);
>>>>>>> @@ -2830,7 +2870,7 @@ static int semanage_direct_install_info(semanage_handle_t *sh,
>>>>>>>                         goto cleanup;
>>>>>>>                 }
>>>>>>>
>>>>>>> -               if (access(path, F_OK) == 0) {
>>>>>>> +               if (stat(path, &sb) == 0) {
>>>>>>>                         ret = unlink(path);
>>>>>>>                         if (ret != 0) {
>>>>>>>                                 ERR(sh, "Error while removing cached CIL file %s: %s", path, strerror(errno));
>>>>>>> diff --git a/libsemanage/src/semanage_store.c b/libsemanage/src/semanage_store.c
>>>>>>> index 4bd1d651..83c188dc 100644
>>>>>>> --- a/libsemanage/src/semanage_store.c
>>>>>>> +++ b/libsemanage/src/semanage_store.c
>>>>>>> @@ -514,6 +514,7 @@ char *semanage_conf_path(void)
>>>>>>>  {
>>>>>>>         char *semanage_conf = NULL;
>>>>>>>         int len;
>>>>>>> +       FILE *fp = NULL;
>>>>>>>
>>>>>>>         len = strlen(semanage_root()) + strlen(selinux_path()) + strlen(SEMANAGE_CONF_FILE);
>>>>>>>         semanage_conf = calloc(len + 1, sizeof(char));
>>>>>>> @@ -522,7 +523,10 @@ char *semanage_conf_path(void)
>>>>>>>         snprintf(semanage_conf, len + 1, "%s%s%s", semanage_root(), selinux_path(),
>>>>>>>                  SEMANAGE_CONF_FILE);
>>>>>>>
>>>>>>> -       if (access(semanage_conf, R_OK) != 0) {
>>>>>>> +       //the following replaces access(semanage_conf, R_OK) check
>>>>>>> +       if ((fp = fopen(semanage_conf, "r")) != NULL) {
>>>>>>> +               fclose(fp);
>>>>>>> +       } else {
>>>>>>>                 snprintf(semanage_conf, len + 1, "%s%s", selinux_path(), SEMANAGE_CONF_FILE);
>>>>>>>         }
>>>>>>>
>>>>>>> @@ -1508,8 +1512,14 @@ int semanage_split_fc(semanage_handle_t * sh)
>>>>>>>  static int sefcontext_compile(semanage_handle_t * sh, const char *path) {
>>>>>>>
>>>>>>>         int r;
>>>>>>> +       struct stat sb;
>>>>>>> +
>>>>>>> +       if (stat(path, &sb) < 0) {
>>>>>>> +               if (errno != ENOENT) {
>>>>>>> +                       ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
>>>>>>> +                       return -1;
>>>>>>> +               }
>>>>>>>
>>>>>>> -       if (access(path, F_OK) != 0) {
>>>>>>>                 return 0;
>>>>>>>         }
>>>>>>>
>>>>>>> --
>>>>>>> 2.14.3
>>>>>>>
>>>>>>>
>>
>>
>>
>



-- 
Respectfully,

William C Roberts

Re: [PATCH 3/3] libsemanage: replace access() checks to make setuid programs work

[Stephen Smalley]

On 02/28/2018 02:44 PM, William Roberts wrote:
> On Wed, Feb 28, 2018 at 11:39 AM, Stephen Smalley <sds@tycho.nsa.gov> wrote:
>> On 02/28/2018 02:26 PM, William Roberts wrote:
>>> So peeking through the code base, I see:
>>>
>>> int semanage_direct_is_managed(semanage_handle_t * sh)
>>> {
>>> if (semanage_check_init(sh, sh->conf->store_root_path))
>>> goto err;
>>>
>>> if (semanage_access_check(sh) < 0)
>>> return 0;
>>>
>>> return 1;
>>>
>>>       err:
>>> ERR(sh, "could not check whether policy is managed");
>>> return STATUS_ERR;
>>> }
>>>
>>> Which semanage_access_check eventually gets down to a raw access check.
>>>
>>> Which is only ever used in test_fcontext
>>>
>>> semanage_access_check is also the only consumer of semanage_direct_access_check
>>>
>>> which is the semanage_store_access_check is only consumed by the
>>> former and test case and
>>> the same could be said for semanage_store_access_check
>>>
>>> I think this is a good time to roll in patch 4 and drop everything
>>> relying on semanage_store_access_check.
>>>
>>> Thoughts?
>>
>> semanage_access_check() is part of the shared library ABI. Can't be
>> removed.  Used by seobject.py via the python bindings.  At most, we can
>> kill all internal users but the ABI has to remain.
> 
> Ahh yes, duh.
> 
> Outside of just killing off internal users of it, should we modify it
> to not use access?
> So it at least works under setuid?

I don't think it is worthwhile, and it isn't clear how one would test
the directory writability case.  Plus semanage_access_check() is only
advisory and the caller is free to ignore the result or not call it in
the first place.  It is really only intended to allow a program to save
itself some work if it isn't going to be able to access the policy store
at all, not as a security feature.  Also, as I've said before, I
wouldn't warrant libsemanage to be safe if called from a setuid program;
no one has ever audited it for such to my knowledge.

Re: [PATCH 3/3] libsemanage: replace access() checks to make setuid programs work

[Stephen Smalley]

On 02/28/2018 03:53 PM, Stephen Smalley wrote:
> On 02/28/2018 02:44 PM, William Roberts wrote:
>> On Wed, Feb 28, 2018 at 11:39 AM, Stephen Smalley <sds@tycho.nsa.gov> wrote:
>>> On 02/28/2018 02:26 PM, William Roberts wrote:
>>>> So peeking through the code base, I see:
>>>>
>>>> int semanage_direct_is_managed(semanage_handle_t * sh)
>>>> {
>>>> if (semanage_check_init(sh, sh->conf->store_root_path))
>>>> goto err;
>>>>
>>>> if (semanage_access_check(sh) < 0)
>>>> return 0;
>>>>
>>>> return 1;
>>>>
>>>>       err:
>>>> ERR(sh, "could not check whether policy is managed");
>>>> return STATUS_ERR;
>>>> }
>>>>
>>>> Which semanage_access_check eventually gets down to a raw access check.
>>>>
>>>> Which is only ever used in test_fcontext
>>>>
>>>> semanage_access_check is also the only consumer of semanage_direct_access_check
>>>>
>>>> which is the semanage_store_access_check is only consumed by the
>>>> former and test case and
>>>> the same could be said for semanage_store_access_check
>>>>
>>>> I think this is a good time to roll in patch 4 and drop everything
>>>> relying on semanage_store_access_check.
>>>>
>>>> Thoughts?
>>>
>>> semanage_access_check() is part of the shared library ABI. Can't be
>>> removed.  Used by seobject.py via the python bindings.  At most, we can
>>> kill all internal users but the ABI has to remain.
>>
>> Ahh yes, duh.
>>
>> Outside of just killing off internal users of it, should we modify it
>> to not use access?
>> So it at least works under setuid?
> 
> I don't think it is worthwhile, and it isn't clear how one would test
> the directory writability case.  Plus semanage_access_check() is only
> advisory and the caller is free to ignore the result or not call it in
> the first place.  It is really only intended to allow a program to save
> itself some work if it isn't going to be able to access the policy store
> at all, not as a security feature.  Also, as I've said before, I
> wouldn't warrant libsemanage to be safe if called from a setuid program;
> no one has ever audited it for such to my knowledge.

By the way, please test that these patches do not end up yielding silent
failures or confusing error messages when users run semanage or semodule
commands with insufficient permissions, e.g. semanage login -l or
semodule -l as non-root.  That's what semanage_access_check() was for,
to check up front and provide a useful error message before doing any
other work.

Re: [PATCH 3/3] libsemanage: replace access() checks to make setuid programs work

[Stephen Smalley]

On 03/01/2018 09:40 AM, Stephen Smalley wrote:
> On 02/28/2018 03:53 PM, Stephen Smalley wrote:
>> On 02/28/2018 02:44 PM, William Roberts wrote:
>>> On Wed, Feb 28, 2018 at 11:39 AM, Stephen Smalley <sds@tycho.nsa.gov> wrote:
>>>> On 02/28/2018 02:26 PM, William Roberts wrote:
>>>>> So peeking through the code base, I see:
>>>>>
>>>>> int semanage_direct_is_managed(semanage_handle_t * sh)
>>>>> {
>>>>> if (semanage_check_init(sh, sh->conf->store_root_path))
>>>>> goto err;
>>>>>
>>>>> if (semanage_access_check(sh) < 0)
>>>>> return 0;
>>>>>
>>>>> return 1;
>>>>>
>>>>>       err:
>>>>> ERR(sh, "could not check whether policy is managed");
>>>>> return STATUS_ERR;
>>>>> }
>>>>>
>>>>> Which semanage_access_check eventually gets down to a raw access check.
>>>>>
>>>>> Which is only ever used in test_fcontext
>>>>>
>>>>> semanage_access_check is also the only consumer of semanage_direct_access_check
>>>>>
>>>>> which is the semanage_store_access_check is only consumed by the
>>>>> former and test case and
>>>>> the same could be said for semanage_store_access_check
>>>>>
>>>>> I think this is a good time to roll in patch 4 and drop everything
>>>>> relying on semanage_store_access_check.
>>>>>
>>>>> Thoughts?
>>>>
>>>> semanage_access_check() is part of the shared library ABI. Can't be
>>>> removed.  Used by seobject.py via the python bindings.  At most, we can
>>>> kill all internal users but the ABI has to remain.
>>>
>>> Ahh yes, duh.
>>>
>>> Outside of just killing off internal users of it, should we modify it
>>> to not use access?
>>> So it at least works under setuid?
>>
>> I don't think it is worthwhile, and it isn't clear how one would test
>> the directory writability case.  Plus semanage_access_check() is only
>> advisory and the caller is free to ignore the result or not call it in
>> the first place.  It is really only intended to allow a program to save
>> itself some work if it isn't going to be able to access the policy store
>> at all, not as a security feature.  Also, as I've said before, I
>> wouldn't warrant libsemanage to be safe if called from a setuid program;
>> no one has ever audited it for such to my knowledge.
> 
> By the way, please test that these patches do not end up yielding silent
> failures or confusing error messages when users run semanage or semodule
> commands with insufficient permissions, e.g. semanage login -l or
> semodule -l as non-root.  That's what semanage_access_check() was for,
> to check up front and provide a useful error message before doing any
> other work.

And for comparison, this is what we get today before these patches:
$ semanage login -l
ValueError: SELinux policy is not managed or store cannot be accessed.

$ semodule -l
libsemanage.semanage_create_store: Could not access module store at
/var/lib/selinux/targeted, or it is not a directory. (Permission denied).
libsemanage.semanage_direct_connect: could not establish direct
connection (Permission denied).
semodule:  Could not connect to policy handler

The messages don't have to be the same, but we need to make sure we have
some useful diagnostic that points to the underlying problem.

Re: [PATCH 3/3] libsemanage: replace access() checks to make setuid programs work

[Stephen Smalley]

On 02/28/2018 05:15 AM, Vit Mojzis wrote:
> access() uses real UID instead of effective UID which causes false
> negative checks in setuid programs.
> Replace access(,F_OK) (i.e. tests for file existence) by stat().
> And access(,R_OK) by fopen(,"r")
> 
> Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1186431
> 
> Signed-off-by: Vit Mojzis <vmojzis@redhat.com>
> ---
>  libsemanage/src/direct_api.c     | 132 +++++++++++++++++++++++++--------------
>  libsemanage/src/semanage_store.c |  14 ++++-
>  2 files changed, 98 insertions(+), 48 deletions(-)
> 
> diff --git a/libsemanage/src/direct_api.c b/libsemanage/src/direct_api.c
> index f4d57cf8..d42a51cd 100644
> --- a/libsemanage/src/direct_api.c
> +++ b/libsemanage/src/direct_api.c
> @@ -140,6 +140,7 @@ int semanage_direct_is_managed(semanage_handle_t * sh)
>  int semanage_direct_connect(semanage_handle_t * sh)
>  {
>  	const char *path;
> +	struct stat sb;
>  
>  	if (semanage_check_init(sh, sh->conf->store_root_path))
>  		goto err;
> @@ -302,10 +303,17 @@ int semanage_direct_connect(semanage_handle_t * sh)
>  
>  	/* set the disable dontaudit value */
>  	path = semanage_path(SEMANAGE_ACTIVE, SEMANAGE_DISABLE_DONTAUDIT);
> -	if (access(path, F_OK) == 0)
> +
> +	if (stat(path, &sb) == 0)
>  		sepol_set_disable_dontaudit(sh->sepolh, 1);
> -	else
> +	else {
> +		if (errno != ENOENT) {
> +			ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
> +			goto err;
> +		}
> +
>  		sepol_set_disable_dontaudit(sh->sepolh, 0);
> +	}
>  
>  	return STATUS_SUCCESS;
>  
> @@ -1139,6 +1147,7 @@ static int semanage_compile_hll_modules(semanage_handle_t *sh,
>  	int status = 0;
>  	int i;
>  	char cil_path[PATH_MAX];
> +	struct stat sb;
>  
>  	assert(sh);
>  	assert(modinfos);
> @@ -1155,9 +1164,13 @@ static int semanage_compile_hll_modules(semanage_handle_t *sh,
>  		}
>  
>  		if (semanage_get_ignore_module_cache(sh) == 0 &&
> -				access(cil_path, F_OK) == 0) {
> +				(status = stat(cil_path, &sb)) == 0) {
>  			continue;
>  		}
> +		if (status != 0 && errno != ENOENT) {
> +			ERR(sh, "Unable to access %s: %s\n", cil_path, strerror(errno));
> +			goto cleanup; //an error in the "stat" call
> +		}
>  
>  		status = semanage_compile_module(sh, &modinfos[i]);
>  		if (status < 0) {
> @@ -1188,6 +1201,7 @@ static int semanage_direct_commit(semanage_handle_t * sh)
>  	struct cil_db *cildb = NULL;
>  	semanage_module_info_t *modinfos = NULL;
>  	mode_t mask = umask(0077);
> +	struct stat sb;
>  
>  	int do_rebuild, do_write_kernel, do_install;
>  	int fcontexts_modified, ports_modified, seusers_modified,
> @@ -1226,10 +1240,16 @@ static int semanage_direct_commit(semanage_handle_t * sh)
>  
>  	/* Create or remove the disable_dontaudit flag file. */
>  	path = semanage_path(SEMANAGE_TMP, SEMANAGE_DISABLE_DONTAUDIT);
> -	if (access(path, F_OK) == 0)
> +	if (stat(path, &sb) == 0)
>  		do_rebuild |= !(sepol_get_disable_dontaudit(sh->sepolh) == 1);
> -	else
> +	else {
> +		if (errno != ENOENT) {
> +			ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
> +			goto cleanup;
> +		}
> +
>  		do_rebuild |= (sepol_get_disable_dontaudit(sh->sepolh) == 1);
> +	}
>  	if (sepol_get_disable_dontaudit(sh->sepolh) == 1) {
>  		FILE *touch;
>  		touch = fopen(path, "w");
> @@ -1251,10 +1271,17 @@ static int semanage_direct_commit(semanage_handle_t * sh)
>  
>  	/* Create or remove the preserve_tunables flag file. */
>  	path = semanage_path(SEMANAGE_TMP, SEMANAGE_PRESERVE_TUNABLES);
> -	if (access(path, F_OK) == 0)
> +	if (stat(path, &sb) == 0)
>  		do_rebuild |= !(sepol_get_preserve_tunables(sh->sepolh) == 1);
> -	else
> +	else {
> +		if (errno != ENOENT) {
> +			ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
> +			goto cleanup;
> +		}
> +
>  		do_rebuild |= (sepol_get_preserve_tunables(sh->sepolh) == 1);
> +	}
> +
>  	if (sepol_get_preserve_tunables(sh->sepolh) == 1) {
>  		FILE *touch;
>  		touch = fopen(path, "w");
> @@ -1291,40 +1318,24 @@ static int semanage_direct_commit(semanage_handle_t * sh)
>  	 * a rebuild.
>  	 */
>  	if (!do_rebuild) {
> -		path = semanage_path(SEMANAGE_TMP, SEMANAGE_STORE_KERNEL);
> -		if (access(path, F_OK) != 0) {
> -			do_rebuild = 1;
> -			goto rebuild;
> -		}
> -
> -		path = semanage_path(SEMANAGE_TMP, SEMANAGE_STORE_FC);
> -		if (access(path, F_OK) != 0) {
> -			do_rebuild = 1;
> -			goto rebuild;
> -		}
> -
> -		path = semanage_path(SEMANAGE_TMP, SEMANAGE_STORE_SEUSERS);
> -		if (access(path, F_OK) != 0) {
> -			do_rebuild = 1;
> -			goto rebuild;
> -		}
> -
> -		path = semanage_path(SEMANAGE_TMP, SEMANAGE_LINKED);
> -		if (access(path, F_OK) != 0) {
> -			do_rebuild = 1;
> -			goto rebuild;
> -		}
> -
> -		path = semanage_path(SEMANAGE_TMP, SEMANAGE_SEUSERS_LINKED);
> -		if (access(path, F_OK) != 0) {
> -			do_rebuild = 1;
> -			goto rebuild;
> -		}
> +		int files[] = {SEMANAGE_STORE_KERNEL,
> +					   SEMANAGE_STORE_FC,
> +					   SEMANAGE_STORE_SEUSERS,
> +					   SEMANAGE_LINKED,
> +					   SEMANAGE_SEUSERS_LINKED,
> +					   SEMANAGE_USERS_EXTRA_LINKED};
> +
> +		for (i = 0; i < (int) sizeof(files); i++) {
> +			path = semanage_path(SEMANAGE_TMP, files[i]);
> +			if (stat(path, &sb) != 0) {
> +				if (errno != ENOENT) {
> +					ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
> +					goto cleanup;
> +				}
>  
> -		path = semanage_path(SEMANAGE_TMP, SEMANAGE_USERS_EXTRA_LINKED);
> -		if (access(path, F_OK) != 0) {
> -			do_rebuild = 1;
> -			goto rebuild;
> +				do_rebuild = 1;
> +				goto rebuild;
> +			}
>  		}
>  	}
>  
> @@ -1457,7 +1468,7 @@ rebuild:
>  			goto cleanup;
>  
>  		path = semanage_path(SEMANAGE_TMP, SEMANAGE_SEUSERS_LINKED);
> -		if (access(path, F_OK) == 0) {
> +		if (stat(path, &sb) == 0) {
>  			retval = semanage_copy_file(path,
>  						    semanage_path(SEMANAGE_TMP,
>  								  SEMANAGE_STORE_SEUSERS),
> @@ -1466,11 +1477,16 @@ rebuild:
>  				goto cleanup;
>  			pseusers->dtable->drop_cache(pseusers->dbase);
>  		} else {
> +			if (errno != ENOENT) {
> +				ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
> +				goto cleanup;
> +			}
> +
>  			pseusers->dtable->clear(sh, pseusers->dbase);
>  		}
>  
>  		path = semanage_path(SEMANAGE_TMP, SEMANAGE_USERS_EXTRA_LINKED);
> -		if (access(path, F_OK) == 0) {
> +		if (stat(path, &sb) == 0) {
>  			retval = semanage_copy_file(path,
>  						    semanage_path(SEMANAGE_TMP,
>  								  SEMANAGE_USERS_EXTRA),
> @@ -1479,6 +1495,11 @@ rebuild:
>  				goto cleanup;
>  			pusers_extra->dtable->drop_cache(pusers_extra->dbase);
>  		} else {
> +			if (errno != ENOENT) {
> +				ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
> +				goto cleanup;
> +			}
> +
>  			pusers_extra->dtable->clear(sh, pusers_extra->dbase);
>  		}
>  	}
> @@ -1809,6 +1830,7 @@ static int semanage_direct_extract(semanage_handle_t * sh,
>  	ssize_t _data_len;
>  	char *_data;
>  	int compressed;
> +	struct stat sb;
>  
>  	/* get path of module */
>  	rc = semanage_module_get_path(
> @@ -1821,8 +1843,8 @@ static int semanage_direct_extract(semanage_handle_t * sh,
>  		goto cleanup;
>  	}
>  
> -	if (access(module_path, F_OK) != 0) {
> -		ERR(sh, "Module does not exist: %s", module_path);
> +	if (stat(module_path, &sb) != 0) {
> +		ERR(sh, "Unable to access %s: %s\n", module_path, strerror(errno));
>  		rc = -1;
>  		goto cleanup;
>  	}
> @@ -1851,7 +1873,12 @@ static int semanage_direct_extract(semanage_handle_t * sh,
>  		goto cleanup;
>  	}
>  
> -	if (extract_cil == 1 && strcmp(_modinfo->lang_ext, "cil") && access(input_file, F_OK) != 0) {
> +	if (extract_cil == 1 && strcmp(_modinfo->lang_ext, "cil") && stat(input_file, &sb) != 0) {
> +		if (errno != ENOENT) {
> +			ERR(sh, "Unable to access %s: %s\n", input_file, strerror(errno));
> +			goto cleanup;
> +		}
> +
>  		rc = semanage_compile_module(sh, _modinfo);
>  		if (rc < 0) {
>  			goto cleanup;
> @@ -1996,6 +2023,12 @@ static int semanage_direct_get_enabled(semanage_handle_t *sh,
>  	}
>  
>  	if (stat(path, &sb) < 0) {
> +		if (errno != ENOENT) {
> +			ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
> +			status = -1;
> +			goto cleanup;
> +		}
> +
>  		*enabled = 1;
>  	}
>  	else {
> @@ -2322,6 +2355,12 @@ static int semanage_direct_get_module_info(semanage_handle_t *sh,
>  
>  	/* set enabled/disabled status */
>  	if (stat(fn, &sb) < 0) {
> +		if (errno != ENOENT) {
> +			ERR(sh, "Unable to access %s: %s\n", fn, strerror(errno));
> +			status = -1;
> +			goto cleanup;
> +		}
> +
>  		ret = semanage_module_info_set_enabled(sh, *modinfo, 1);
>  		if (ret != 0) {
>  			status = -1;
> @@ -2730,6 +2769,7 @@ static int semanage_direct_install_info(semanage_handle_t *sh,
>  	int status = 0;
>  	int ret = 0;
>  	int type;
> +	struct stat sb;
>  
>  	char path[PATH_MAX];
>  	mode_t mask = umask(0077);
> @@ -2830,7 +2870,7 @@ static int semanage_direct_install_info(semanage_handle_t *sh,
>  			goto cleanup;
>  		}
>  
> -		if (access(path, F_OK) == 0) {
> +		if (stat(path, &sb) == 0) {
>  			ret = unlink(path);
>  			if (ret != 0) {
>  				ERR(sh, "Error while removing cached CIL file %s: %s", path, strerror(errno));
> diff --git a/libsemanage/src/semanage_store.c b/libsemanage/src/semanage_store.c
> index 4bd1d651..83c188dc 100644
> --- a/libsemanage/src/semanage_store.c
> +++ b/libsemanage/src/semanage_store.c
> @@ -514,6 +514,7 @@ char *semanage_conf_path(void)
>  {
>  	char *semanage_conf = NULL;
>  	int len;
> +	FILE *fp = NULL;
>  
>  	len = strlen(semanage_root()) + strlen(selinux_path()) + strlen(SEMANAGE_CONF_FILE);
>  	semanage_conf = calloc(len + 1, sizeof(char));
> @@ -522,7 +523,10 @@ char *semanage_conf_path(void)
>  	snprintf(semanage_conf, len + 1, "%s%s%s", semanage_root(), selinux_path(),
>  		 SEMANAGE_CONF_FILE);
>  
> -	if (access(semanage_conf, R_OK) != 0) {
> +	//the following replaces access(semanage_conf, R_OK) check
> +	if ((fp = fopen(semanage_conf, "r")) != NULL) {

Arguably the test should have just been F_OK (i.e. does it exist) and
you can just make it a stat() instead.

> +		fclose(fp);
> +	} else {
>  		snprintf(semanage_conf, len + 1, "%s%s", selinux_path(), SEMANAGE_CONF_FILE);
>  	}
>  
> @@ -1508,8 +1512,14 @@ int semanage_split_fc(semanage_handle_t * sh)
>  static int sefcontext_compile(semanage_handle_t * sh, const char *path) {
>  
>  	int r;
> +	struct stat sb;
> +
> +	if (stat(path, &sb) < 0) {
> +		if (errno != ENOENT) {
> +			ERR(sh, "Unable to access %s: %s\n", path, strerror(errno));
> +			return -1;
> +		}
>  
> -	if (access(path, F_OK) != 0) {
>  		return 0;
>  	}
>  
>