Merge branch 'upstream' of git://git.infradead.org/users/pcmoore/audit

Pull audit fixes from Paul Moore:
 "Seven audit patches for v4.1, all bug fixes.

  The largest, and perhaps most significant commit helps resolve some
  memory pressure issues related to the inode cache and audit, there are
  also a few small commits which help resolve some timing issues with
  the audit log queue, and the rest fall into the always popular "code
  clean-up" category.

  In general, nothing really substantial, just a nice set of maintenance
  patches"

* 'upstream' of git://git.infradead.org/users/pcmoore/audit:
  audit: Remove condition which always evaluates to false
  audit: reduce mmap_sem hold for mm->exe_file
  audit: consolidate handling of mm->exe_file
  audit: code clean up
  audit: don't reset working wait time accidentally with auditd
  audit: don't lose set wait time on first successful call to audit_log_start()
  audit: move the tree pruning to a dedicated thread

kernel/audit.c

@@ -43,6 +43,7 @@
 
 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 
+#include <linux/file.h>
 #include <linux/init.h>
 #include <linux/types.h>
 #include <linux/atomic.h>
@@ -107,6 +108,7 @@ static u32	audit_rate_limit;
  * When set to zero, this means unlimited. */
 static u32	audit_backlog_limit = 64;
 #define AUDIT_BACKLOG_WAIT_TIME (60 * HZ)
+static u32	audit_backlog_wait_time_master = AUDIT_BACKLOG_WAIT_TIME;
 static u32	audit_backlog_wait_time = AUDIT_BACKLOG_WAIT_TIME;
 static u32	audit_backlog_wait_overflow = 0;
 
@@ -338,13 +340,13 @@ static int audit_set_backlog_limit(u32 limit)
 static int audit_set_backlog_wait_time(u32 timeout)
 {
 	return audit_do_config_change("audit_backlog_wait_time",
-				      &audit_backlog_wait_time, timeout);
+				      &audit_backlog_wait_time_master, timeout);
 }
 
 static int audit_set_enabled(u32 state)
 {
 	int rc;
-	if (state < AUDIT_OFF || state > AUDIT_LOCKED)
+	if (state > AUDIT_LOCKED)
 		return -EINVAL;
 
 	rc =  audit_do_config_change("audit_enabled", &audit_enabled, state);
@@ -663,7 +665,7 @@ static int audit_netlink_ok(struct sk_buff *skb, u16 msg_type)
 	case AUDIT_MAKE_EQUIV:
 		/* Only support auditd and auditctl in initial pid namespace
 		 * for now. */
-		if ((task_active_pid_ns(current) != &init_pid_ns))
+		if (task_active_pid_ns(current) != &init_pid_ns)
 			return -EPERM;
 
 		if (!netlink_capable(skb, CAP_AUDIT_CONTROL))
@@ -834,7 +836,7 @@ static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
 		s.lost			= atomic_read(&audit_lost);
 		s.backlog		= skb_queue_len(&audit_skb_queue);
 		s.feature_bitmap	= AUDIT_FEATURE_BITMAP_ALL;
-		s.backlog_wait_time	= audit_backlog_wait_time;
+		s.backlog_wait_time	= audit_backlog_wait_time_master;
 		audit_send_reply(skb, seq, AUDIT_GET, 0, 0, &s, sizeof(s));
 		break;
 	}
@@ -877,8 +879,7 @@ static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
 		if (s.mask & AUDIT_STATUS_BACKLOG_WAIT_TIME) {
 			if (sizeof(s) > (size_t)nlh->nlmsg_len)
 				return -EINVAL;
-			if (s.backlog_wait_time < 0 ||
+			if (s.backlog_wait_time > 10*AUDIT_BACKLOG_WAIT_TIME)
-			    s.backlog_wait_time > 10*AUDIT_BACKLOG_WAIT_TIME)
 				return -EINVAL;
 			err = audit_set_backlog_wait_time(s.backlog_wait_time);
 			if (err < 0)
@@ -1385,7 +1386,8 @@ struct audit_buffer *audit_log_start(struct audit_context *ctx, gfp_t gfp_mask,
 		return NULL;
 	}
 
-	audit_backlog_wait_time = AUDIT_BACKLOG_WAIT_TIME;
+	if (!reserve)
+		audit_backlog_wait_time = audit_backlog_wait_time_master;
 
 	ab = audit_buffer_alloc(ctx, gfp_mask, type);
 	if (!ab) {
@@ -1759,7 +1761,7 @@ void audit_log_name(struct audit_context *context, struct audit_names *n,
 	} else
 		audit_log_format(ab, " name=(null)");
 
-	if (n->ino != (unsigned long)-1) {
+	if (n->ino != (unsigned long)-1)
 		audit_log_format(ab, " inode=%lu"
 				 " dev=%02x:%02x mode=%#ho"
 				 " ouid=%u ogid=%u rdev=%02x:%02x",
@@ -1771,7 +1773,6 @@ void audit_log_name(struct audit_context *context, struct audit_names *n,
 				 from_kgid(&init_user_ns, n->gid),
 				 MAJOR(n->rdev),
 				 MINOR(n->rdev));
-	}
 	if (n->osid != 0) {
 		char *ctx = NULL;
 		u32 len;
@@ -1838,11 +1839,29 @@ error_path:
 }
 EXPORT_SYMBOL(audit_log_task_context);
 
+void audit_log_d_path_exe(struct audit_buffer *ab,
+			  struct mm_struct *mm)
+{
+	struct file *exe_file;
+
+	if (!mm)
+		goto out_null;
+
+	exe_file = get_mm_exe_file(mm);
+	if (!exe_file)
+		goto out_null;
+
+	audit_log_d_path(ab, " exe=", &exe_file->f_path);
+	fput(exe_file);
+	return;
+out_null:
+	audit_log_format(ab, " exe=(null)");
+}
+
 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)
@@ -1878,13 +1897,7 @@ 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) {
+	audit_log_d_path_exe(ab, tsk->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_task_context(ab);
 }
 EXPORT_SYMBOL(audit_log_task_info);

kernel/audit.h

@@ -257,6 +257,9 @@ 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/audit_tree.c

@@ -37,6 +37,7 @@ struct audit_chunk {
 
 static LIST_HEAD(tree_list);
 static LIST_HEAD(prune_list);
+static struct task_struct *prune_thread;
 
 /*
  * One struct chunk is attached to each inode of interest.
@@ -651,6 +652,57 @@ static int tag_mount(struct vfsmount *mnt, void *arg)
 	return tag_chunk(mnt->mnt_root->d_inode, arg);
 }
 
+/*
+ * That gets run when evict_chunk() ends up needing to kill audit_tree.
+ * Runs from a separate thread.
+ */
+static int prune_tree_thread(void *unused)
+{
+	for (;;) {
+		set_current_state(TASK_INTERRUPTIBLE);
+		if (list_empty(&prune_list))
+			schedule();
+		__set_current_state(TASK_RUNNING);
+
+		mutex_lock(&audit_cmd_mutex);
+		mutex_lock(&audit_filter_mutex);
+
+		while (!list_empty(&prune_list)) {
+			struct audit_tree *victim;
+
+			victim = list_entry(prune_list.next,
+					struct audit_tree, list);
+			list_del_init(&victim->list);
+
+			mutex_unlock(&audit_filter_mutex);
+
+			prune_one(victim);
+
+			mutex_lock(&audit_filter_mutex);
+		}
+
+		mutex_unlock(&audit_filter_mutex);
+		mutex_unlock(&audit_cmd_mutex);
+	}
+	return 0;
+}
+
+static int audit_launch_prune(void)
+{
+	if (prune_thread)
+		return 0;
+	prune_thread = kthread_create(prune_tree_thread, NULL,
+				"audit_prune_tree");
+	if (IS_ERR(prune_thread)) {
+		pr_err("cannot start thread audit_prune_tree");
+		prune_thread = NULL;
+		return -ENOMEM;
+	} else {
+		wake_up_process(prune_thread);
+		return 0;
+	}
+}
+
 /* called with audit_filter_mutex */
 int audit_add_tree_rule(struct audit_krule *rule)
 {
@@ -674,6 +726,12 @@ int audit_add_tree_rule(struct audit_krule *rule)
 	/* do not set rule->tree yet */
 	mutex_unlock(&audit_filter_mutex);
 
+	if (unlikely(!prune_thread)) {
+		err = audit_launch_prune();
+		if (err)
+			goto Err;
+	}
+
 	err = kern_path(tree->pathname, 0, &path);
 	if (err)
 		goto Err;
@@ -811,36 +869,10 @@ int audit_tag_tree(char *old, char *new)
 	return failed;
 }
 
-/*
- * That gets run when evict_chunk() ends up needing to kill audit_tree.
- * Runs from a separate thread.
- */
-static int prune_tree_thread(void *unused)
-{
-	mutex_lock(&audit_cmd_mutex);
-	mutex_lock(&audit_filter_mutex);
-
-	while (!list_empty(&prune_list)) {
-		struct audit_tree *victim;
-
-		victim = list_entry(prune_list.next, struct audit_tree, list);
-		list_del_init(&victim->list);
-
-		mutex_unlock(&audit_filter_mutex);
-
-		prune_one(victim);
-
-		mutex_lock(&audit_filter_mutex);
-	}
-
-	mutex_unlock(&audit_filter_mutex);
-	mutex_unlock(&audit_cmd_mutex);
-	return 0;
-}
 
 static void audit_schedule_prune(void)
 {
-	kthread_run(prune_tree_thread, NULL, "audit_prune_tree");
+	wake_up_process(prune_thread);
 }
 
 /*
@@ -907,9 +939,9 @@ static void evict_chunk(struct audit_chunk *chunk)
 	for (n = 0; n < chunk->count; n++)
 		list_del_init(&chunk->owners[n].list);
 	spin_unlock(&hash_lock);
+	mutex_unlock(&audit_filter_mutex);
 	if (need_prune)
 		audit_schedule_prune();
-	mutex_unlock(&audit_filter_mutex);
 }
 
 static int audit_tree_handle_event(struct fsnotify_group *group,

kernel/auditsc.c

@@ -2361,7 +2361,6 @@ 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);
@@ -2376,13 +2375,7 @@ 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) {
+	audit_log_d_path_exe(ab, current->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)");
 }
 
 /**