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From: Casey Schaufler <casey@schaufler-ca.com>
To: James Morris <jmorris@namei.org>,
	LSM <linux-security-module@vger.kernel.org>,
	LKLM <linux-kernel@vger.kernel.org>,
	SE Linux <selinux@tycho.nsa.gov>
Cc: "John Johansen" <john.johansen@canonical.com>,
	"Kees Cook" <keescook@chromium.org>,
	"Tetsuo Handa" <penguin-kernel@i-love.sakura.ne.jp>,
	"Paul Moore" <paul@paul-moore.com>,
	"linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
	"Stephen Smalley" <sds@tycho.nsa.gov>,
	"Alexey Dobriyan" <adobriyan@gmail.com>,
	"Mickaël Salaün" <mic@digikod.net>,
	"Salvatore Mesoraca" <s.mesoraca16@gmail.com>
Subject: [PATCH v5 26/38] TOMOYO: Abstract use of cred security blob
Date: Mon, 26 Nov 2018 15:46:41 -0800
Message-ID: <2ba69559-bb0a-a87a-d829-1e43012074b6@schaufler-ca.com> (raw)
In-Reply-To: <50db058a-7dde-441b-a7f9-f6837fe8b69f@schaufler-ca.com>

Don't use the cred->security pointer directly.
Provide helper functions that provide the security blob pointer.

Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
[kees: adjusted for ordered init series]
Signed-off-by: Kees Cook <keescook@chromium.org>
---
 security/tomoyo/common.h        | 21 +++++++++++++++++++--
 security/tomoyo/domain.c        |  4 +++-
 security/tomoyo/securityfs_if.c | 15 +++++++++++----
 security/tomoyo/tomoyo.c        | 40 +++++++++++++++++++++++++++++++---------
 4 files changed, 64 insertions(+), 16 deletions(-)

diff --git a/security/tomoyo/common.h b/security/tomoyo/common.h
index 539bcdd30bb8..41898613d93b 100644
--- a/security/tomoyo/common.h
+++ b/security/tomoyo/common.h
@@ -29,6 +29,7 @@
 #include <linux/in.h>
 #include <linux/in6.h>
 #include <linux/un.h>
+#include <linux/lsm_hooks.h>
 #include <net/sock.h>
 #include <net/af_unix.h>
 #include <net/ip.h>
@@ -1062,6 +1063,7 @@ void tomoyo_write_log2(struct tomoyo_request_info *r, int len, const char *fmt,
 /********** External variable definitions. **********/
 
 extern bool tomoyo_policy_loaded;
+extern int tomoyo_enabled;
 extern const char * const tomoyo_condition_keyword
 [TOMOYO_MAX_CONDITION_KEYWORD];
 extern const char * const tomoyo_dif[TOMOYO_MAX_DOMAIN_INFO_FLAGS];
@@ -1196,6 +1198,17 @@ static inline void tomoyo_put_group(struct tomoyo_group *group)
 		atomic_dec(&group->head.users);
 }
 
+/**
+ * tomoyo_cred - Get a pointer to the tomoyo cred security blob
+ * @cred - the relevant cred
+ *
+ * Returns pointer to the tomoyo cred blob.
+ */
+static inline struct tomoyo_domain_info **tomoyo_cred(const struct cred *cred)
+{
+	return (struct tomoyo_domain_info **)&cred->security;
+}
+
 /**
  * tomoyo_domain - Get "struct tomoyo_domain_info" for current thread.
  *
@@ -1203,7 +1216,9 @@ static inline void tomoyo_put_group(struct tomoyo_group *group)
  */
 static inline struct tomoyo_domain_info *tomoyo_domain(void)
 {
-	return current_cred()->security;
+	struct tomoyo_domain_info **blob = tomoyo_cred(current_cred());
+
+	return *blob;
 }
 
 /**
@@ -1216,7 +1231,9 @@ static inline struct tomoyo_domain_info *tomoyo_domain(void)
 static inline struct tomoyo_domain_info *tomoyo_real_domain(struct task_struct
 							    *task)
 {
-	return task_cred_xxx(task, security);
+	struct tomoyo_domain_info **blob = tomoyo_cred(get_task_cred(task));
+
+	return *blob;
 }
 
 /**
diff --git a/security/tomoyo/domain.c b/security/tomoyo/domain.c
index f6758dad981f..b7469fdbff01 100644
--- a/security/tomoyo/domain.c
+++ b/security/tomoyo/domain.c
@@ -678,6 +678,7 @@ static int tomoyo_environ(struct tomoyo_execve *ee)
  */
 int tomoyo_find_next_domain(struct linux_binprm *bprm)
 {
+	struct tomoyo_domain_info **blob;
 	struct tomoyo_domain_info *old_domain = tomoyo_domain();
 	struct tomoyo_domain_info *domain = NULL;
 	const char *original_name = bprm->filename;
@@ -843,7 +844,8 @@ int tomoyo_find_next_domain(struct linux_binprm *bprm)
 		domain = old_domain;
 	/* Update reference count on "struct tomoyo_domain_info". */
 	atomic_inc(&domain->users);
-	bprm->cred->security = domain;
+	blob = tomoyo_cred(bprm->cred);
+	*blob = domain;
 	kfree(exename.name);
 	if (!retval) {
 		ee->r.domain = domain;
diff --git a/security/tomoyo/securityfs_if.c b/security/tomoyo/securityfs_if.c
index 1d3d7e7a1f05..768dff9608b1 100644
--- a/security/tomoyo/securityfs_if.c
+++ b/security/tomoyo/securityfs_if.c
@@ -71,9 +71,12 @@ static ssize_t tomoyo_write_self(struct file *file, const char __user *buf,
 				if (!cred) {
 					error = -ENOMEM;
 				} else {
-					struct tomoyo_domain_info *old_domain =
-						cred->security;
-					cred->security = new_domain;
+					struct tomoyo_domain_info **blob;
+					struct tomoyo_domain_info *old_domain;
+
+					blob = tomoyo_cred(cred);
+					old_domain = *blob;
+					*blob = new_domain;
 					atomic_inc(&new_domain->users);
 					atomic_dec(&old_domain->users);
 					commit_creds(cred);
@@ -234,10 +237,14 @@ static void __init tomoyo_create_entry(const char *name, const umode_t mode,
  */
 static int __init tomoyo_initerface_init(void)
 {
+	struct tomoyo_domain_info *domain;
 	struct dentry *tomoyo_dir;
 
+	if (!tomoyo_enabled)
+		return 0;
+	domain = tomoyo_domain();
 	/* Don't create securityfs entries unless registered. */
-	if (current_cred()->security != &tomoyo_kernel_domain)
+	if (domain != &tomoyo_kernel_domain)
 		return 0;
 
 	tomoyo_dir = securityfs_create_dir("tomoyo", NULL);
diff --git a/security/tomoyo/tomoyo.c b/security/tomoyo/tomoyo.c
index daff7d7897ad..15864307925d 100644
--- a/security/tomoyo/tomoyo.c
+++ b/security/tomoyo/tomoyo.c
@@ -18,7 +18,9 @@
  */
 static int tomoyo_cred_alloc_blank(struct cred *new, gfp_t gfp)
 {
-	new->security = NULL;
+	struct tomoyo_domain_info **blob = tomoyo_cred(new);
+
+	*blob = NULL;
 	return 0;
 }
 
@@ -34,8 +36,13 @@ static int tomoyo_cred_alloc_blank(struct cred *new, gfp_t gfp)
 static int tomoyo_cred_prepare(struct cred *new, const struct cred *old,
 			       gfp_t gfp)
 {
-	struct tomoyo_domain_info *domain = old->security;
-	new->security = domain;
+	struct tomoyo_domain_info **old_blob = tomoyo_cred(old);
+	struct tomoyo_domain_info **new_blob = tomoyo_cred(new);
+	struct tomoyo_domain_info *domain;
+
+	domain = *old_blob;
+	*new_blob = domain;
+
 	if (domain)
 		atomic_inc(&domain->users);
 	return 0;
@@ -59,7 +66,9 @@ static void tomoyo_cred_transfer(struct cred *new, const struct cred *old)
  */
 static void tomoyo_cred_free(struct cred *cred)
 {
-	struct tomoyo_domain_info *domain = cred->security;
+	struct tomoyo_domain_info **blob = tomoyo_cred(cred);
+	struct tomoyo_domain_info *domain = *blob;
+
 	if (domain)
 		atomic_dec(&domain->users);
 }
@@ -73,6 +82,9 @@ static void tomoyo_cred_free(struct cred *cred)
  */
 static int tomoyo_bprm_set_creds(struct linux_binprm *bprm)
 {
+	struct tomoyo_domain_info **blob;
+	struct tomoyo_domain_info *domain;
+
 	/*
 	 * Do only if this function is called for the first time of an execve
 	 * operation.
@@ -93,13 +105,14 @@ static int tomoyo_bprm_set_creds(struct linux_binprm *bprm)
 	 * stored inside "bprm->cred->security" will be acquired later inside
 	 * tomoyo_find_next_domain().
 	 */
-	atomic_dec(&((struct tomoyo_domain_info *)
-		     bprm->cred->security)->users);
+	blob = tomoyo_cred(bprm->cred);
+	domain = *blob;
+	atomic_dec(&domain->users);
 	/*
 	 * Tell tomoyo_bprm_check_security() is called for the first time of an
 	 * execve operation.
 	 */
-	bprm->cred->security = NULL;
+	*blob = NULL;
 	return 0;
 }
 
@@ -112,8 +125,11 @@ static int tomoyo_bprm_set_creds(struct linux_binprm *bprm)
  */
 static int tomoyo_bprm_check_security(struct linux_binprm *bprm)
 {
-	struct tomoyo_domain_info *domain = bprm->cred->security;
+	struct tomoyo_domain_info **blob;
+	struct tomoyo_domain_info *domain;
 
+	blob = tomoyo_cred(bprm->cred);
+	domain = *blob;
 	/*
 	 * Execute permission is checked against pathname passed to do_execve()
 	 * using current domain.
@@ -531,6 +547,8 @@ static struct security_hook_list tomoyo_hooks[] __lsm_ro_after_init = {
 /* Lock for GC. */
 DEFINE_SRCU(tomoyo_ss);
 
+int tomoyo_enabled __lsm_ro_after_init = 1;
+
 /**
  * tomoyo_init - Register TOMOYO Linux as a LSM module.
  *
@@ -539,17 +557,21 @@ DEFINE_SRCU(tomoyo_ss);
 static int __init tomoyo_init(void)
 {
 	struct cred *cred = (struct cred *) current_cred();
+	struct tomoyo_domain_info **blob;
 
 	/* register ourselves with the security framework */
 	security_add_hooks(tomoyo_hooks, ARRAY_SIZE(tomoyo_hooks), "tomoyo");
 	printk(KERN_INFO "TOMOYO Linux initialized\n");
-	cred->security = &tomoyo_kernel_domain;
+	blob = tomoyo_cred(cred);
+	*blob = &tomoyo_kernel_domain;
 	tomoyo_mm_init();
+
 	return 0;
 }
 
 DEFINE_LSM(tomoyo) = {
 	.name = "tomoyo",
+	.enabled = &tomoyo_enabled,
 	.flags = LSM_FLAG_LEGACY_MAJOR | LSM_FLAG_EXCLUSIVE,
 	.init = tomoyo_init,
 };
-- 
2.14.5



  parent reply index

Thread overview: 55+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-11-26 23:22 [PATCH v5 00/38] LSM: Module stacking for SARA and Landlock Casey Schaufler
2018-11-26 23:26 ` [PATCH v5 01/38] LSM: Introduce LSM_FLAG_LEGACY_MAJOR Casey Schaufler
2018-11-27  5:34   ` Kees Cook
2018-11-27 13:51     ` Ondrej Mosnacek
2018-11-27 19:27     ` Casey Schaufler
2018-11-26 23:27 ` [PATCH v5 02/38] LSM: Provide separate ordered initialization Casey Schaufler
2018-11-26 23:28 ` [PATCH v5 03/38] LSM: Plumb visibility into optional "enabled" state Casey Schaufler
2018-11-26 23:29 ` [PATCH v5 04/38] LSM: Lift LSM selection out of individual LSMs Casey Schaufler
2018-11-26 23:30 ` [PATCH v5 05/38] LSM: Build ordered list of LSMs to initialize Casey Schaufler
2018-11-26 23:31 ` [PATCH v5 06/38] LSM: Introduce CONFIG_LSM Casey Schaufler
2018-11-26 23:31 ` [PATCH v5 07/38] LSM: Introduce "lsm=" for boottime LSM selection Casey Schaufler
2018-11-26 23:32 ` [PATCH v5 08/38] LSM: Tie enabling logic to presence in ordered list Casey Schaufler
2018-11-26 23:33 ` [PATCH v5 09/38] LSM: Prepare for reorganizing "security=" logic Casey Schaufler
2018-11-26 23:34 ` [PATCH v5 10/38] LSM: Refactor "security=" in terms of enable/disable Casey Schaufler
2018-11-26 23:34 ` [PATCH v5 11/38] LSM: Separate idea of "major" LSM from "exclusive" LSM Casey Schaufler
2018-11-26 23:35 ` [PATCH v5 12/38] apparmor: Remove SECURITY_APPARMOR_BOOTPARAM_VALUE Casey Schaufler
2018-11-26 23:36 ` [PATCH v5 13/38] selinux: Remove SECURITY_SELINUX_BOOTPARAM_VALUE Casey Schaufler
2018-11-26 23:37 ` [PATCH v5 14/38] LSM: Add all exclusive LSMs to ordered initialization Casey Schaufler
2018-11-26 23:38 ` [PATCH v5 15/38] LSM: Split LSM preparation from initialization Casey Schaufler
2018-11-26 23:39 ` [PATCH v5 16/38] LoadPin: Initialize as ordered LSM Casey Schaufler
2018-11-26 23:39 ` [PATCH v5 17/38] Yama: " Casey Schaufler
2018-11-26 23:40 ` [PATCH v5 18/38] LSM: Introduce enum lsm_order Casey Schaufler
2018-11-26 23:41 ` [PATCH v5 19/38] capability: Initialize as LSM_ORDER_FIRST Casey Schaufler
2018-11-26 23:41 ` [PATCH v5 20/38] procfs: add smack subdir to attrs Casey Schaufler
2018-11-26 23:42 ` [PATCH v5 21/38] Smack: Abstract use of cred security blob Casey Schaufler
2018-11-26 23:43 ` [PATCH v5 22/38] SELinux: " Casey Schaufler
2018-11-26 23:44 ` [PATCH v5 23/38] SELinux: Remove cred security blob poisoning Casey Schaufler
2018-11-26 23:45 ` [PATCH v5 24/38] SELinux: Remove unused selinux_is_enabled Casey Schaufler
2018-11-26 23:45 ` [PATCH v5 25/38] AppArmor: Abstract use of cred security blob Casey Schaufler
2018-11-26 23:46 ` Casey Schaufler [this message]
2018-11-26 23:47 ` [PATCH v5 27/38] Infrastructure management of the " Casey Schaufler
2018-11-26 23:48 ` [PATCH v5 28/38] SELinux: Abstract use of file " Casey Schaufler
2018-11-26 23:49 ` [PATCH v5 29/38] Smack: " Casey Schaufler
2018-11-26 23:50 ` [PATCH v5 30/38] LSM: Infrastructure management of the file security Casey Schaufler
2018-11-26 23:51 ` [PATCH v5 31/38] SELinux: Abstract use of inode security blob Casey Schaufler
2018-11-26 23:52 ` [PATCH v5 32/38] Smack: " Casey Schaufler
2018-11-26 23:53 ` [PATCH v5 33/38] LSM: Infrastructure management of the inode security Casey Schaufler
2018-11-26 23:53 ` [PATCH v5 34/38] LSM: Infrastructure management of the task security Casey Schaufler
2018-11-26 23:54 ` [PATCH v5 35/38] SELinux: Abstract use of ipc security blobs Casey Schaufler
2018-11-26 23:55 ` [PATCH v5 36/38] Smack: " Casey Schaufler
2018-11-26 23:56 ` [PATCH v5 37/38] LSM: Infrastructure management of the ipc security blob Casey Schaufler
2018-11-26 23:57 ` [PATCH v5 38/38] TOMOYO: Update LSM flags to no longer be exclusive Casey Schaufler
2018-12-05  0:31 ` [PATCH v5 00/38] LSM: Module stacking for SARA and Landlock Kees Cook
2018-12-05  2:37   ` Casey Schaufler
2018-12-05  2:52     ` John Johansen
2018-12-11 18:57   ` James Morris
2018-12-11 21:02     ` Tetsuo Handa
2018-12-12 19:33       ` James Morris
2018-12-11 21:19     ` Kees Cook
2019-01-08  1:29       ` Kees Cook
2019-01-08 21:05         ` James Morris
2019-01-08 21:37           ` Casey Schaufler
2019-01-08 21:42             ` Kees Cook
2019-01-08 23:05               ` Casey Schaufler
2018-12-11 22:42 Casey Schaufler
2018-12-11 22:43 ` [PATCH v5 26/38] TOMOYO: Abstract use of cred security blob Casey Schaufler

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