path: root/security/integrity
diff options
authorKees Cook <>2020-10-02 10:38:20 -0700
committerGreg Kroah-Hartman <>2020-10-05 13:37:03 +0200
commitb64fcae74b6d6940d14243c963ab0089e8f0d82d (patch)
tree301791490a1bce0d017a380cc37475510ecee286 /security/integrity
parent885352881f11f1f3113d8eb877786bcb6d720544 (diff)
LSM: Introduce kernel_post_load_data() hook
There are a few places in the kernel where LSMs would like to have visibility into the contents of a kernel buffer that has been loaded or read. While security_kernel_post_read_file() (which includes the buffer) exists as a pairing for security_kernel_read_file(), no such hook exists to pair with security_kernel_load_data(). Earlier proposals for just using security_kernel_post_read_file() with a NULL file argument were rejected (i.e. "file" should always be valid for the security_..._file hooks, but it appears at least one case was left in the kernel during earlier refactoring. (This will be fixed in a subsequent patch.) Since not all cases of security_kernel_load_data() can have a single contiguous buffer made available to the LSM hook (e.g. kexec image segments are separately loaded), there needs to be a way for the LSM to reason about its expectations of the hook coverage. In order to handle this, add a "contents" argument to the "kernel_load_data" hook that indicates if the newly added "kernel_post_load_data" hook will be called with the full contents once loaded. That way, LSMs requiring full contents can choose to unilaterally reject "kernel_load_data" with contents=false (which is effectively the existing hook coverage), but when contents=true they can allow it and later evaluate the "kernel_post_load_data" hook once the buffer is loaded. With this change, LSMs can gain coverage over non-file-backed data loads (e.g. init_module(2) and firmware userspace helper), which will happen in subsequent patches. Additionally prepare IMA to start processing these cases. Signed-off-by: Kees Cook <> Reviewed-by: KP Singh <> Link: Signed-off-by: Greg Kroah-Hartman <>
Diffstat (limited to 'security/integrity')
1 files changed, 23 insertions, 1 deletions
diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
index 5f89970c5ab7..9dd9c5f4d736 100644
--- a/security/integrity/ima/ima_main.c
+++ b/security/integrity/ima/ima_main.c
@@ -676,6 +676,8 @@ int ima_post_read_file(struct file *file, void *buf, loff_t size,
* ima_load_data - appraise decision based on policy
* @id: kernel load data caller identifier
+ * @contents: whether the full contents will be available in a later
+ * call to ima_post_load_data().
* Callers of this LSM hook can not measure, appraise, or audit the
* data provided by userspace. Enforce policy rules requring a file
@@ -683,7 +685,7 @@ int ima_post_read_file(struct file *file, void *buf, loff_t size,
* For permission return 0, otherwise return -EACCES.
-int ima_load_data(enum kernel_load_data_id id)
+int ima_load_data(enum kernel_load_data_id id, bool contents)
bool ima_enforce, sig_enforce;
@@ -723,6 +725,26 @@ int ima_load_data(enum kernel_load_data_id id)
return 0;
+ * ima_post_load_data - appraise decision based on policy
+ * @buf: pointer to in memory file contents
+ * @size: size of in memory file contents
+ * @id: kernel load data caller identifier
+ * @description: @id-specific description of contents
+ *
+ * Measure/appraise/audit in memory buffer based on policy. Policy rules
+ * are written in terms of a policy identifier.
+ *
+ * On success return 0. On integrity appraisal error, assuming the file
+ * is in policy and IMA-appraisal is in enforcing mode, return -EACCES.
+ */
+int ima_post_load_data(char *buf, loff_t size,
+ enum kernel_load_data_id load_id,
+ char *description)
+ return 0;
* process_buffer_measurement - Measure the buffer to ima log.
* @inode: inode associated with the object being measured (NULL for KEY_CHECK)