audit: consolidate handling of mm->exe_file

This patch adds a audit_log_d_path_exe() helper function
to share how we handle auditing of the exe_file's path.
Used by both audit and auditsc. No functionality is changed.

Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
[PM: tweaked subject line]
Signed-off-by: Paul Moore <pmoore@redhat.com>

kernel/audit.c

@@ -1848,11 +1848,24 @@ int audit_log_task_context(struct audit_buffer *ab)
 }
 EXPORT_SYMBOL(audit_log_task_context);
 
+void audit_log_d_path_exe(struct audit_buffer *ab,
+			  struct mm_struct *mm)
+{
+	if (!mm) {
+		audit_log_format(ab, " exe=(null)");
+		return;
+	}
+
+	down_read(&mm->mmap_sem);
+	if (mm->exe_file)
+		audit_log_d_path(ab, " exe=", &mm->exe_file->f_path);
+	up_read(&mm->mmap_sem);
+}
+
 void audit_log_task_info(struct audit_buffer *ab, struct task_struct *tsk)
 {
 	const struct cred *cred;
 	char comm[sizeof(tsk->comm)];
-	struct mm_struct *mm = tsk->mm;
 	char *tty;
 
 	if (!ab)
@@ -1888,13 +1901,7 @@ void audit_log_task_info(struct audit_buffer *ab, struct task_struct *tsk)
 	audit_log_format(ab, " comm=");
 	audit_log_untrustedstring(ab, get_task_comm(comm, tsk));
 
-	if (mm) {
-		down_read(&mm->mmap_sem);
-		if (mm->exe_file)
-			audit_log_d_path(ab, " exe=", &mm->exe_file->f_path);
-		up_read(&mm->mmap_sem);
-	} else
-		audit_log_format(ab, " exe=(null)");
+	audit_log_d_path_exe(ab, tsk->mm);
 	audit_log_task_context(ab);
 }
 EXPORT_SYMBOL(audit_log_task_info);

kernel/audit.h

@@ -270,6 +270,9 @@ extern struct list_head audit_filter_list[];
 
 extern struct audit_entry *audit_dupe_rule(struct audit_krule *old);
 
+extern void audit_log_d_path_exe(struct audit_buffer *ab,
+				 struct mm_struct *mm);
+
 /* audit watch functions */
 #ifdef CONFIG_AUDIT_WATCH
 extern void audit_put_watch(struct audit_watch *watch);

kernel/auditsc.c

@@ -2460,7 +2460,6 @@ static void audit_log_task(struct audit_buffer *ab)
 	kuid_t auid, uid;
 	kgid_t gid;
 	unsigned int sessionid;
-	struct mm_struct *mm = current->mm;
 	char comm[sizeof(current->comm)];
 
 	auid = audit_get_loginuid(current);
@@ -2475,13 +2474,7 @@ static void audit_log_task(struct audit_buffer *ab)
 	audit_log_task_context(ab);
 	audit_log_format(ab, " pid=%d comm=", task_pid_nr(current));
 	audit_log_untrustedstring(ab, get_task_comm(comm, current));
-	if (mm) {
-		down_read(&mm->mmap_sem);
-		if (mm->exe_file)
-			audit_log_d_path(ab, " exe=", &mm->exe_file->f_path);
-		up_read(&mm->mmap_sem);
-	} else
-		audit_log_format(ab, " exe=(null)");
+	audit_log_d_path_exe(ab, current->mm);
 }
 
 /**