From: Kees Cook <keescook@chromium.org>
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Kees Cook <keescook@chromium.org>,
Scott Branden <scott.branden@broadcom.com>,
Mimi Zohar <zohar@linux.ibm.com>,
Luis Chamberlain <mcgrof@kernel.org>,
Takashi Iwai <tiwai@suse.de>, Jessica Yu <jeyu@kernel.org>,
SeongJae Park <sjpark@amazon.de>, KP Singh <kpsingh@chromium.org>,
linux-efi@vger.kernel.org, linux-security-module@vger.kernel.org,
linux-integrity@vger.kernel.org, selinux@vger.kernel.org,
linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH v4 12/17] LSM: Add "contents" flag to kernel_read_file hook
Date: Wed, 29 Jul 2020 10:58:40 -0700 [thread overview]
Message-ID: <20200729175845.1745471-13-keescook@chromium.org> (raw)
In-Reply-To: <20200729175845.1745471-1-keescook@chromium.org>
As with the kernel_load_data LSM hook, add a "contents" flag to the
kernel_read_file LSM hook that indicates whether the LSM can expect
a matching call to the kernel_post_read_file LSM hook with the full
contents of the file. With the coming addition of partial file read
support for kernel_read_file*() API, the LSM will no longer be able
to always see the entire contents of a file during the read calls.
For cases where the LSM must read examine the complete file contents,
it will need to do so on its own every time the kernel_read_file
hook is called with contents=false (or reject such cases). Adjust all
existing LSMs to retain existing behavior.
Signed-off-by: Kees Cook <keescook@chromium.org>
---
fs/kernel_read_file.c | 2 +-
include/linux/ima.h | 6 ++++--
include/linux/lsm_hook_defs.h | 2 +-
include/linux/lsm_hooks.h | 3 +++
include/linux/security.h | 6 ++++--
security/integrity/ima/ima_main.c | 10 +++++++++-
security/loadpin/loadpin.c | 14 ++++++++++++--
security/security.c | 7 ++++---
security/selinux/hooks.c | 5 +++--
9 files changed, 41 insertions(+), 14 deletions(-)
diff --git a/fs/kernel_read_file.c b/fs/kernel_read_file.c
index 2e29c38eb4df..d73bc3fa710a 100644
--- a/fs/kernel_read_file.c
+++ b/fs/kernel_read_file.c
@@ -39,7 +39,7 @@ int kernel_read_file(struct file *file, void **buf,
if (ret)
return ret;
- ret = security_kernel_read_file(file, id);
+ ret = security_kernel_read_file(file, id, true);
if (ret)
goto out;
diff --git a/include/linux/ima.h b/include/linux/ima.h
index 502e36ad7804..259023039dc9 100644
--- a/include/linux/ima.h
+++ b/include/linux/ima.h
@@ -23,7 +23,8 @@ extern int ima_file_mprotect(struct vm_area_struct *vma, unsigned long prot);
extern int ima_load_data(enum kernel_load_data_id id, bool contents);
extern int ima_post_load_data(char *buf, loff_t size,
enum kernel_load_data_id id);
-extern int ima_read_file(struct file *file, enum kernel_read_file_id id);
+extern int ima_read_file(struct file *file, enum kernel_read_file_id id,
+ bool contents);
extern int ima_post_read_file(struct file *file, void *buf, loff_t size,
enum kernel_read_file_id id);
extern void ima_post_path_mknod(struct dentry *dentry);
@@ -91,7 +92,8 @@ static inline int ima_post_load_data(char *buf, loff_t size,
return 0;
}
-static inline int ima_read_file(struct file *file, enum kernel_read_file_id id)
+static inline int ima_read_file(struct file *file, enum kernel_read_file_id id,
+ bool contents)
{
return 0;
}
diff --git a/include/linux/lsm_hook_defs.h b/include/linux/lsm_hook_defs.h
index 7ed5d31ac9cc..f953aa938eaf 100644
--- a/include/linux/lsm_hook_defs.h
+++ b/include/linux/lsm_hook_defs.h
@@ -188,7 +188,7 @@ LSM_HOOK(int, 0, kernel_load_data, enum kernel_load_data_id id, bool contents)
LSM_HOOK(int, 0, kernel_post_load_data, char *buf, loff_t size,
enum kernel_read_file_id id)
LSM_HOOK(int, 0, kernel_read_file, struct file *file,
- enum kernel_read_file_id id)
+ enum kernel_read_file_id id, bool contents)
LSM_HOOK(int, 0, kernel_post_read_file, struct file *file, char *buf,
loff_t size, enum kernel_read_file_id id)
LSM_HOOK(int, 0, task_fix_setuid, struct cred *new, const struct cred *old,
diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h
index 812d626195fc..b66433b5aa15 100644
--- a/include/linux/lsm_hooks.h
+++ b/include/linux/lsm_hooks.h
@@ -650,6 +650,7 @@
* @file contains the file structure pointing to the file being read
* by the kernel.
* @id kernel read file identifier
+ * @contents if a subsequent @kernel_post_read_file will be called.
* Return 0 if permission is granted.
* @kernel_post_read_file:
* Read a file specified by userspace.
@@ -658,6 +659,8 @@
* @buf pointer to buffer containing the file contents.
* @size length of the file contents.
* @id kernel read file identifier
+ * This must be paired with a prior @kernel_read_file call that had
+ * @contents set to true.
* Return 0 if permission is granted.
* @task_fix_setuid:
* Update the module's state after setting one or more of the user
diff --git a/include/linux/security.h b/include/linux/security.h
index e748974c707b..a5d66b89cd6c 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -390,7 +390,8 @@ int security_kernel_module_request(char *kmod_name);
int security_kernel_load_data(enum kernel_load_data_id id, bool contents);
int security_kernel_post_load_data(char *buf, loff_t size,
enum kernel_load_data_id id);
-int security_kernel_read_file(struct file *file, enum kernel_read_file_id id);
+int security_kernel_read_file(struct file *file, enum kernel_read_file_id id,
+ bool contents);
int security_kernel_post_read_file(struct file *file, char *buf, loff_t size,
enum kernel_read_file_id id);
int security_task_fix_setuid(struct cred *new, const struct cred *old,
@@ -1028,7 +1029,8 @@ static inline int security_kernel_post_load_data(char *buf, loff_t size,
}
static inline int security_kernel_read_file(struct file *file,
- enum kernel_read_file_id id)
+ enum kernel_read_file_id id,
+ bool contents)
{
return 0;
}
diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
index 1a7bc4c7437d..dc4f90660aa6 100644
--- a/security/integrity/ima/ima_main.c
+++ b/security/integrity/ima/ima_main.c
@@ -602,6 +602,7 @@ void ima_post_path_mknod(struct dentry *dentry)
* ima_read_file - pre-measure/appraise hook decision based on policy
* @file: pointer to the file to be measured/appraised/audit
* @read_id: caller identifier
+ * @contents: whether a subsequent call will be made to ima_post_read_file()
*
* Permit reading a file based on policy. The policy rules are written
* in terms of the policy identifier. Appraising the integrity of
@@ -609,8 +610,15 @@ void ima_post_path_mknod(struct dentry *dentry)
*
* For permission return 0, otherwise return -EACCES.
*/
-int ima_read_file(struct file *file, enum kernel_read_file_id read_id)
+int ima_read_file(struct file *file, enum kernel_read_file_id read_id,
+ bool contents)
{
+ /* Reject all partial reads during appraisal. */
+ if (!contents) {
+ if (ima_appraise & IMA_APPRAISE_ENFORCE)
+ return -EACCES;
+ }
+
/*
* Do devices using pre-allocated memory run the risk of the
* firmware being accessible to the device prior to the completion
diff --git a/security/loadpin/loadpin.c b/security/loadpin/loadpin.c
index db320a43f42e..a1778ebef137 100644
--- a/security/loadpin/loadpin.c
+++ b/security/loadpin/loadpin.c
@@ -117,11 +117,21 @@ static void loadpin_sb_free_security(struct super_block *mnt_sb)
}
}
-static int loadpin_read_file(struct file *file, enum kernel_read_file_id id)
+static int loadpin_read_file(struct file *file, enum kernel_read_file_id id,
+ bool contents)
{
struct super_block *load_root;
const char *origin = kernel_read_file_id_str(id);
+ /*
+ * If we will not know that we'll be seeing the full contents
+ * then we cannot trust a load will be complete and unchanged
+ * off disk. Treat all contents=false hooks as if there were
+ * no associated file struct.
+ */
+ if (!contents)
+ file = NULL;
+
/* If the file id is excluded, ignore the pinning. */
if ((unsigned int)id < ARRAY_SIZE(ignore_read_file_id) &&
ignore_read_file_id[id]) {
@@ -178,7 +188,7 @@ static int loadpin_read_file(struct file *file, enum kernel_read_file_id id)
static int loadpin_load_data(enum kernel_load_data_id id, bool contents)
{
- return loadpin_read_file(NULL, (enum kernel_read_file_id) id);
+ return loadpin_read_file(NULL, (enum kernel_read_file_id) id, contents);
}
static struct security_hook_list loadpin_hooks[] __lsm_ro_after_init = {
diff --git a/security/security.c b/security/security.c
index 568bb77e84f4..6a38fc533a5a 100644
--- a/security/security.c
+++ b/security/security.c
@@ -1672,14 +1672,15 @@ int security_kernel_module_request(char *kmod_name)
return integrity_kernel_module_request(kmod_name);
}
-int security_kernel_read_file(struct file *file, enum kernel_read_file_id id)
+int security_kernel_read_file(struct file *file, enum kernel_read_file_id id,
+ bool contents)
{
int ret;
- ret = call_int_hook(kernel_read_file, 0, file, id);
+ ret = call_int_hook(kernel_read_file, 0, file, id, contents);
if (ret)
return ret;
- return ima_read_file(file, id);
+ return ima_read_file(file, id, contents);
}
EXPORT_SYMBOL_GPL(security_kernel_read_file);
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 1a5c68196faf..6d183bbc12a6 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -4004,13 +4004,14 @@ static int selinux_kernel_module_from_file(struct file *file)
}
static int selinux_kernel_read_file(struct file *file,
- enum kernel_read_file_id id)
+ enum kernel_read_file_id id,
+ bool contents)
{
int rc = 0;
switch (id) {
case READING_MODULE:
- rc = selinux_kernel_module_from_file(file);
+ rc = selinux_kernel_module_from_file(contents ? file : NULL);
break;
default:
break;
--
2.25.1
next prev parent reply other threads:[~2020-07-29 17:59 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-29 17:58 [PATCH v4 00/17] Introduce partial kernel_read_file() support Kees Cook
2020-07-29 17:58 ` [PATCH v4 01/17] test_firmware: Test platform fw loading on non-EFI systems Kees Cook
2020-07-29 17:58 ` [PATCH v4 02/17] fs/kernel_read_file: Remove FIRMWARE_PREALLOC_BUFFER enum Kees Cook
2020-07-29 17:58 ` [PATCH v4 03/17] fs/kernel_read_file: Remove FIRMWARE_EFI_EMBEDDED enum Kees Cook
2020-07-29 17:58 ` [PATCH v4 04/17] fs/kernel_read_file: Split into separate include file Kees Cook
2020-07-30 2:22 ` James Morris
2020-07-29 17:58 ` [PATCH v4 05/17] fs/kernel_read_file: Split into separate source file Kees Cook
2020-07-29 17:58 ` [PATCH v4 06/17] fs/kernel_read_file: Remove redundant size argument Kees Cook
2020-07-30 2:25 ` James Morris
2020-07-29 17:58 ` [PATCH v4 07/17] fs/kernel_read_file: Switch buffer size arg to size_t Kees Cook
2020-07-30 2:25 ` James Morris
2020-07-29 17:58 ` [PATCH v4 08/17] fs/kernel_read_file: Add file_size output argument Kees Cook
2020-07-30 2:26 ` James Morris
2020-07-29 17:58 ` [PATCH v4 09/17] LSM: Introduce kernel_post_load_data() hook Kees Cook
2020-08-06 21:59 ` Mimi Zohar
2020-08-07 0:21 ` KP Singh
2020-07-29 17:58 ` [PATCH v4 10/17] firmware_loader: Use security_post_load_data() Kees Cook
2020-08-06 22:07 ` Mimi Zohar
2020-07-29 17:58 ` [PATCH v4 11/17] module: Call security_kernel_post_load_data() Kees Cook
2020-08-05 14:53 ` Jessica Yu
2020-08-07 0:22 ` KP Singh
2020-07-29 17:58 ` Kees Cook [this message]
2020-08-07 0:23 ` [PATCH v4 12/17] LSM: Add "contents" flag to kernel_read_file hook Mimi Zohar
2020-07-29 17:58 ` [PATCH v4 13/17] IMA: Add support for file reads without contents Kees Cook
2020-07-29 17:58 ` [PATCH v4 14/17] fs/kernel_file_read: Add "offset" arg for partial reads Kees Cook
2020-07-29 17:58 ` [PATCH v4 15/17] firmware: Store opt_flags in fw_priv Kees Cook
2020-07-29 17:58 ` [PATCH v4 16/17] firmware: Add request_partial_firmware_into_buf() Kees Cook
2020-07-29 17:58 ` [PATCH v4 17/17] test_firmware: Test partial read support Kees Cook
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