Merge tag 'audit-pr-20191126' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/audit

Pull audit updates from Paul Moore:
 "Audit is back for v5.5, albeit with only two patches:

   - Allow for the auditing of suspicious O_CREAT usage via the new
     AUDIT_ANOM_CREAT record.

   - Remove a redundant if-conditional check found during code analysis.
     It's a minor change, but when the pull request is only two patches
     long, you need filler in the pull request email"

[ Heh on the pull request filler. I wish more people tried to write
  better pull request messages, even if maybe it's not worth it for the
  trivial cases ;^)   - Linus ]

* tag 'audit-pr-20191126' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/audit:
  audit: remove redundant condition check in kauditd_thread()
  audit: Report suspicious O_CREAT usage

fs/namei.c

@@ -925,7 +925,7 @@ static inline int may_follow_link(struct nameidata *nd)
 		return -ECHILD;
 
 	audit_inode(nd->name, nd->stack[0].link.dentry, 0);
-	audit_log_link_denied("follow_link");
+	audit_log_path_denied(AUDIT_ANOM_LINK, "follow_link");
 	return -EACCES;
 }
 
@@ -993,7 +993,7 @@ static int may_linkat(struct path *link)
 	if (safe_hardlink_source(inode) || inode_owner_or_capable(inode))
 		return 0;
 
-	audit_log_link_denied("linkat");
+	audit_log_path_denied(AUDIT_ANOM_LINK, "linkat");
 	return -EPERM;
 }
 
@@ -1031,6 +1031,10 @@ static int may_create_in_sticky(struct dentry * const dir,
 	    (dir->d_inode->i_mode & 0020 &&
 	     ((sysctl_protected_fifos >= 2 && S_ISFIFO(inode->i_mode)) ||
 	      (sysctl_protected_regular >= 2 && S_ISREG(inode->i_mode))))) {
+		const char *operation = S_ISFIFO(inode->i_mode) ?
+					"sticky_create_fifo" :
+					"sticky_create_regular";
+		audit_log_path_denied(AUDIT_ANOM_CREAT, operation);
 		return -EACCES;
 	}
 	return 0;

include/linux/audit.h

@@ -156,7 +156,8 @@ extern void		    audit_log_d_path(struct audit_buffer *ab,
 					     const struct path *path);
 extern void		    audit_log_key(struct audit_buffer *ab,
 					  char *key);
-extern void		    audit_log_link_denied(const char *operation);
+extern void		    audit_log_path_denied(int type,
+						  const char *operation);
 extern void		    audit_log_lost(const char *message);
 
 extern int audit_log_task_context(struct audit_buffer *ab);
@@ -217,7 +218,7 @@ static inline void audit_log_d_path(struct audit_buffer *ab,
 { }
 static inline void audit_log_key(struct audit_buffer *ab, char *key)
 { }
-static inline void audit_log_link_denied(const char *string)
+static inline void audit_log_path_denied(int type, const char *operation)
 { }
 static inline int audit_log_task_context(struct audit_buffer *ab)
 {

include/uapi/linux/audit.h

@@ -143,6 +143,7 @@
 #define AUDIT_ANOM_PROMISCUOUS      1700 /* Device changed promiscuous mode */
 #define AUDIT_ANOM_ABEND            1701 /* Process ended abnormally */
 #define AUDIT_ANOM_LINK		    1702 /* Suspicious use of file links */
+#define AUDIT_ANOM_CREAT	    1703 /* Suspicious file creation */
 #define AUDIT_INTEGRITY_DATA	    1800 /* Data integrity verification */
 #define AUDIT_INTEGRITY_METADATA    1801 /* Metadata integrity verification */
 #define AUDIT_INTEGRITY_STATUS	    1802 /* Integrity enable status */

kernel/audit.c

@@ -830,7 +830,7 @@ static int kauditd_thread(void *dummy)
 		rc = kauditd_send_queue(sk, portid,
 					&audit_hold_queue, UNICAST_RETRIES,
 					NULL, kauditd_rehold_skb);
-		if (ac && rc < 0) {
+		if (rc < 0) {
 			sk = NULL;
 			auditd_reset(ac);
 			goto main_queue;
@@ -840,7 +840,7 @@ static int kauditd_thread(void *dummy)
 		rc = kauditd_send_queue(sk, portid,
 					&audit_retry_queue, UNICAST_RETRIES,
 					NULL, kauditd_hold_skb);
-		if (ac && rc < 0) {
+		if (rc < 0) {
 			sk = NULL;
 			auditd_reset(ac);
 			goto main_queue;
@@ -2155,18 +2155,19 @@ void audit_log_task_info(struct audit_buffer *ab)
 EXPORT_SYMBOL(audit_log_task_info);
 
 /**
- * audit_log_link_denied - report a link restriction denial
- * @operation: specific link operation
+ * audit_log_path_denied - report a path restriction denial
+ * @type: audit message type (AUDIT_ANOM_LINK, AUDIT_ANOM_CREAT, etc)
+ * @operation: specific operation name
  */
-void audit_log_link_denied(const char *operation)
+void audit_log_path_denied(int type, const char *operation)
 {
 	struct audit_buffer *ab;
 
 	if (!audit_enabled || audit_dummy_context())
 		return;
 
-	/* Generate AUDIT_ANOM_LINK with subject, operation, outcome. */
-	ab = audit_log_start(audit_context(), GFP_KERNEL, AUDIT_ANOM_LINK);
+	/* Generate log with subject, operation, outcome. */
+	ab = audit_log_start(audit_context(), GFP_KERNEL, type);
 	if (!ab)
 		return;
 	audit_log_format(ab, "op=%s", operation);