[PATCH v3 2/5] IMA: Define an IMA hook to measure LSM data

[Lakshmi Ramasubramanian <nramas@linux.microsoft.com>]

IMA subsystem needs to define an IMA hook that the security modules can
call to measure critical data of the security modules.

Define a new IMA hook, namely ima_lsm_state(), that the security modules
can call to measure data.

Signed-off-by: Lakshmi Ramasubramanian <nramas@linux.microsoft.com>
---
 include/linux/ima.h               |  4 ++++
 security/integrity/ima/ima_main.c | 17 +++++++++++++++++
 2 files changed, 21 insertions(+)

diff --git a/include/linux/ima.h b/include/linux/ima.h
index 9164e1534ec9..7e2686f4953a 100644
--- a/include/linux/ima.h
+++ b/include/linux/ima.h
@@ -26,6 +26,7 @@ extern int ima_post_read_file(struct file *file, void *buf, loff_t size,
 extern void ima_post_path_mknod(struct dentry *dentry);
 extern int ima_file_hash(struct file *file, char *buf, size_t buf_size);
 extern void ima_kexec_cmdline(const void *buf, int size);
+extern void ima_lsm_state(const char *lsm_event_name, const void *buf, int size);
 
 #ifdef CONFIG_IMA_KEXEC
 extern void ima_add_kexec_buffer(struct kimage *image);
@@ -104,6 +105,9 @@ static inline int ima_file_hash(struct file *file, char *buf, size_t buf_size)
 }
 
 static inline void ima_kexec_cmdline(const void *buf, int size) {}
+
+static inline void ima_lsm_state(const char *lsm_event_name,
+				 const void *buf, int size) {}
 #endif /* CONFIG_IMA */
 
 #ifndef CONFIG_IMA_KEXEC
diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
index 8351b2fd48e0..04d9a1d35300 100644
--- a/security/integrity/ima/ima_main.c
+++ b/security/integrity/ima/ima_main.c
@@ -835,6 +835,23 @@ void ima_kexec_cmdline(const void *buf, int size)
 					   KEXEC_CMDLINE, 0, NULL);
 }
 
+/**
+ * ima_lsm_state - measure LSM specific state
+ * @lsm_event_name: LSM event
+ * @buf: pointer to buffer containing LSM specific state
+ * @size: Number of bytes in buf
+ *
+ * Buffers can only be measured, not appraised.
+ */
+void ima_lsm_state(const char *lsm_event_name, const void *buf, int size)
+{
+	if (!lsm_event_name || !buf || !size)
+		return;
+
+	process_buffer_measurement(buf, size, lsm_event_name,
+				   LSM_STATE, 0, NULL);
+}
+
 static int __init init_ima(void)
 {
 	int error;
-- 
2.27.0