ima: audit log hashes

This adds an 'audit' policy action which audit logs file measurements.

Changelog v6:
 - use new action flag handling (Dmitry Kasatkin).
 - removed whitespace (Mimi)

Changelog v5:
 - use audit_log_untrustedstring.

Changelog v4:
 - cleanup digest -> hash conversion.
 - use filename rather than d_path in ima_audit_measurement.

Changelog v3:
 - Use newly exported audit_log_task_info for logging pid/ppid/uid/etc.
 - Update the ima_policy ABI documentation.

Changelog v2:
 - Use 'audit' action rather than 'measure_and_audit' to permit
 auditing in the absence of measuring..

Changelog v1:
 - Initial posting.

Signed-off-by: Peter Moody <pmoody@google.com>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>

1 files changed, 31 insertions, 1 deletions

diff --git a/security/integrity/ima/ima_api.c b/security/integrity/ima/ima_api.c
index f0d60e754b3e..b356884fb3ef 100644
--- a/security/integrity/ima/ima_api.c
+++ b/security/integrity/ima/ima_api.c
@@ -114,7 +114,7 @@ err_out:
  */
 int ima_get_action(struct inode *inode, int mask, int function)
 {
-	int flags = IMA_MEASURE | IMA_APPRAISE;
+	int flags = IMA_MEASURE | IMA_AUDIT | IMA_APPRAISE;
 
 	if (!ima_appraise)
 		flags &= ~IMA_APPRAISE;
@@ -207,3 +207,33 @@ void ima_store_measurement(struct integrity_iint_cache *iint,
 	if (result < 0)
 		kfree(entry);
 }
+
+void ima_audit_measurement(struct integrity_iint_cache *iint,
+			   const unsigned char *filename)
+{
+	struct audit_buffer *ab;
+	char hash[(IMA_DIGEST_SIZE * 2) + 1];
+	int i;
+
+	if (iint->flags & IMA_AUDITED)
+		return;
+
+	for (i = 0; i < IMA_DIGEST_SIZE; i++)
+		hex_byte_pack(hash + (i * 2), iint->ima_xattr.digest[i]);
+	hash[i * 2] = '\0';
+
+	ab = audit_log_start(current->audit_context, GFP_KERNEL,
+			     AUDIT_INTEGRITY_RULE);
+	if (!ab)
+		return;
+
+	audit_log_format(ab, "file=");
+	audit_log_untrustedstring(ab, filename);
+	audit_log_format(ab, " hash=");
+	audit_log_untrustedstring(ab, hash);
+
+	audit_log_task_info(ab, current);
+	audit_log_end(ab);
+
+	iint->flags |= IMA_AUDITED;
+}