Adding upstream version 6.6.15.upstream/6.6.15

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1086 insertions, 0 deletions

diff --git a/kernel/audit_tree.c b/kernel/audit_tree.c
new file mode 100644
index 0000000000..e867c17d3f
--- /dev/null
+++ b/kernel/audit_tree.c
@@ -0,0 +1,1086 @@
+// SPDX-License-Identifier: GPL-2.0
+#include "audit.h"
+#include <linux/fsnotify_backend.h>
+#include <linux/namei.h>
+#include <linux/mount.h>
+#include <linux/kthread.h>
+#include <linux/refcount.h>
+#include <linux/slab.h>
+
+struct audit_tree;
+struct audit_chunk;
+
+struct audit_tree {
+	refcount_t count;
+	int goner;
+	struct audit_chunk *root;
+	struct list_head chunks;
+	struct list_head rules;
+	struct list_head list;
+	struct list_head same_root;
+	struct rcu_head head;
+	char pathname[];
+};
+
+struct audit_chunk {
+	struct list_head hash;
+	unsigned long key;
+	struct fsnotify_mark *mark;
+	struct list_head trees;		/* with root here */
+	int count;
+	atomic_long_t refs;
+	struct rcu_head head;
+	struct audit_node {
+		struct list_head list;
+		struct audit_tree *owner;
+		unsigned index;		/* index; upper bit indicates 'will prune' */
+	} owners[];
+};
+
+struct audit_tree_mark {
+	struct fsnotify_mark mark;
+	struct audit_chunk *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 through
+ * audit_tree_mark (fsnotify mark). We replace struct chunk on tagging /
+ * untagging, the mark is stable as long as there is chunk attached. The
+ * association between mark and chunk is protected by hash_lock and
+ * audit_tree_group->mark_mutex. Thus as long as we hold
+ * audit_tree_group->mark_mutex and check that the mark is alive by
+ * FSNOTIFY_MARK_FLAG_ATTACHED flag check, we are sure the mark points to
+ * the current chunk.
+ *
+ * Rules have pointer to struct audit_tree.
+ * Rules have struct list_head rlist forming a list of rules over
+ * the same tree.
+ * References to struct chunk are collected at audit_inode{,_child}()
+ * time and used in AUDIT_TREE rule matching.
+ * These references are dropped at the same time we are calling
+ * audit_free_names(), etc.
+ *
+ * Cyclic lists galore:
+ * tree.chunks anchors chunk.owners[].list			hash_lock
+ * tree.rules anchors rule.rlist				audit_filter_mutex
+ * chunk.trees anchors tree.same_root				hash_lock
+ * chunk.hash is a hash with middle bits of watch.inode as
+ * a hash function.						RCU, hash_lock
+ *
+ * tree is refcounted; one reference for "some rules on rules_list refer to
+ * it", one for each chunk with pointer to it.
+ *
+ * chunk is refcounted by embedded .refs. Mark associated with the chunk holds
+ * one chunk reference. This reference is dropped either when a mark is going
+ * to be freed (corresponding inode goes away) or when chunk attached to the
+ * mark gets replaced. This reference must be dropped using
+ * audit_mark_put_chunk() to make sure the reference is dropped only after RCU
+ * grace period as it protects RCU readers of the hash table.
+ *
+ * node.index allows to get from node.list to containing chunk.
+ * MSB of that sucker is stolen to mark taggings that we might have to
+ * revert - several operations have very unpleasant cleanup logics and
+ * that makes a difference.  Some.
+ */
+
+static struct fsnotify_group *audit_tree_group;
+static struct kmem_cache *audit_tree_mark_cachep __read_mostly;
+
+static struct audit_tree *alloc_tree(const char *s)
+{
+	struct audit_tree *tree;
+
+	tree = kmalloc(struct_size(tree, pathname, strlen(s) + 1), GFP_KERNEL);
+	if (tree) {
+		refcount_set(&tree->count, 1);
+		tree->goner = 0;
+		INIT_LIST_HEAD(&tree->chunks);
+		INIT_LIST_HEAD(&tree->rules);
+		INIT_LIST_HEAD(&tree->list);
+		INIT_LIST_HEAD(&tree->same_root);
+		tree->root = NULL;
+		strcpy(tree->pathname, s);
+	}
+	return tree;
+}
+
+static inline void get_tree(struct audit_tree *tree)
+{
+	refcount_inc(&tree->count);
+}
+
+static inline void put_tree(struct audit_tree *tree)
+{
+	if (refcount_dec_and_test(&tree->count))
+		kfree_rcu(tree, head);
+}
+
+/* to avoid bringing the entire thing in audit.h */
+const char *audit_tree_path(struct audit_tree *tree)
+{
+	return tree->pathname;
+}
+
+static void free_chunk(struct audit_chunk *chunk)
+{
+	int i;
+
+	for (i = 0; i < chunk->count; i++) {
+		if (chunk->owners[i].owner)
+			put_tree(chunk->owners[i].owner);
+	}
+	kfree(chunk);
+}
+
+void audit_put_chunk(struct audit_chunk *chunk)
+{
+	if (atomic_long_dec_and_test(&chunk->refs))
+		free_chunk(chunk);
+}
+
+static void __put_chunk(struct rcu_head *rcu)
+{
+	struct audit_chunk *chunk = container_of(rcu, struct audit_chunk, head);
+	audit_put_chunk(chunk);
+}
+
+/*
+ * Drop reference to the chunk that was held by the mark. This is the reference
+ * that gets dropped after we've removed the chunk from the hash table and we
+ * use it to make sure chunk cannot be freed before RCU grace period expires.
+ */
+static void audit_mark_put_chunk(struct audit_chunk *chunk)
+{
+	call_rcu(&chunk->head, __put_chunk);
+}
+
+static inline struct audit_tree_mark *audit_mark(struct fsnotify_mark *mark)
+{
+	return container_of(mark, struct audit_tree_mark, mark);
+}
+
+static struct audit_chunk *mark_chunk(struct fsnotify_mark *mark)
+{
+	return audit_mark(mark)->chunk;
+}
+
+static void audit_tree_destroy_watch(struct fsnotify_mark *mark)
+{
+	kmem_cache_free(audit_tree_mark_cachep, audit_mark(mark));
+}
+
+static struct fsnotify_mark *alloc_mark(void)
+{
+	struct audit_tree_mark *amark;
+
+	amark = kmem_cache_zalloc(audit_tree_mark_cachep, GFP_KERNEL);
+	if (!amark)
+		return NULL;
+	fsnotify_init_mark(&amark->mark, audit_tree_group);
+	amark->mark.mask = FS_IN_IGNORED;
+	return &amark->mark;
+}
+
+static struct audit_chunk *alloc_chunk(int count)
+{
+	struct audit_chunk *chunk;
+	int i;
+
+	chunk = kzalloc(struct_size(chunk, owners, count), GFP_KERNEL);
+	if (!chunk)
+		return NULL;
+
+	INIT_LIST_HEAD(&chunk->hash);
+	INIT_LIST_HEAD(&chunk->trees);
+	chunk->count = count;
+	atomic_long_set(&chunk->refs, 1);
+	for (i = 0; i < count; i++) {
+		INIT_LIST_HEAD(&chunk->owners[i].list);
+		chunk->owners[i].index = i;
+	}
+	return chunk;
+}
+
+enum {HASH_SIZE = 128};
+static struct list_head chunk_hash_heads[HASH_SIZE];
+static __cacheline_aligned_in_smp DEFINE_SPINLOCK(hash_lock);
+
+/* Function to return search key in our hash from inode. */
+static unsigned long inode_to_key(const struct inode *inode)
+{
+	/* Use address pointed to by connector->obj as the key */
+	return (unsigned long)&inode->i_fsnotify_marks;
+}
+
+static inline struct list_head *chunk_hash(unsigned long key)
+{
+	unsigned long n = key / L1_CACHE_BYTES;
+	return chunk_hash_heads + n % HASH_SIZE;
+}
+
+/* hash_lock & mark->group->mark_mutex is held by caller */
+static void insert_hash(struct audit_chunk *chunk)
+{
+	struct list_head *list;
+
+	/*
+	 * Make sure chunk is fully initialized before making it visible in the
+	 * hash. Pairs with a data dependency barrier in READ_ONCE() in
+	 * audit_tree_lookup().
+	 */
+	smp_wmb();
+	WARN_ON_ONCE(!chunk->key);
+	list = chunk_hash(chunk->key);
+	list_add_rcu(&chunk->hash, list);
+}
+
+/* called under rcu_read_lock */
+struct audit_chunk *audit_tree_lookup(const struct inode *inode)
+{
+	unsigned long key = inode_to_key(inode);
+	struct list_head *list = chunk_hash(key);
+	struct audit_chunk *p;
+
+	list_for_each_entry_rcu(p, list, hash) {
+		/*
+		 * We use a data dependency barrier in READ_ONCE() to make sure
+		 * the chunk we see is fully initialized.
+		 */
+		if (READ_ONCE(p->key) == key) {
+			atomic_long_inc(&p->refs);
+			return p;
+		}
+	}
+	return NULL;
+}
+
+bool audit_tree_match(struct audit_chunk *chunk, struct audit_tree *tree)
+{
+	int n;
+	for (n = 0; n < chunk->count; n++)
+		if (chunk->owners[n].owner == tree)
+			return true;
+	return false;
+}
+
+/* tagging and untagging inodes with trees */
+
+static struct audit_chunk *find_chunk(struct audit_node *p)
+{
+	int index = p->index & ~(1U<<31);
+	p -= index;
+	return container_of(p, struct audit_chunk, owners[0]);
+}
+
+static void replace_mark_chunk(struct fsnotify_mark *mark,
+			       struct audit_chunk *chunk)
+{
+	struct audit_chunk *old;
+
+	assert_spin_locked(&hash_lock);
+	old = mark_chunk(mark);
+	audit_mark(mark)->chunk = chunk;
+	if (chunk)
+		chunk->mark = mark;
+	if (old)
+		old->mark = NULL;
+}
+
+static void replace_chunk(struct audit_chunk *new, struct audit_chunk *old)
+{
+	struct audit_tree *owner;
+	int i, j;
+
+	new->key = old->key;
+	list_splice_init(&old->trees, &new->trees);
+	list_for_each_entry(owner, &new->trees, same_root)
+		owner->root = new;
+	for (i = j = 0; j < old->count; i++, j++) {
+		if (!old->owners[j].owner) {
+			i--;
+			continue;
+		}
+		owner = old->owners[j].owner;
+		new->owners[i].owner = owner;
+		new->owners[i].index = old->owners[j].index - j + i;
+		if (!owner) /* result of earlier fallback */
+			continue;
+		get_tree(owner);
+		list_replace_init(&old->owners[j].list, &new->owners[i].list);
+	}
+	replace_mark_chunk(old->mark, new);
+	/*
+	 * Make sure chunk is fully initialized before making it visible in the
+	 * hash. Pairs with a data dependency barrier in READ_ONCE() in
+	 * audit_tree_lookup().
+	 */
+	smp_wmb();
+	list_replace_rcu(&old->hash, &new->hash);
+}
+
+static void remove_chunk_node(struct audit_chunk *chunk, struct audit_node *p)
+{
+	struct audit_tree *owner = p->owner;
+
+	if (owner->root == chunk) {
+		list_del_init(&owner->same_root);
+		owner->root = NULL;
+	}
+	list_del_init(&p->list);
+	p->owner = NULL;
+	put_tree(owner);
+}
+
+static int chunk_count_trees(struct audit_chunk *chunk)
+{
+	int i;
+	int ret = 0;
+
+	for (i = 0; i < chunk->count; i++)
+		if (chunk->owners[i].owner)
+			ret++;
+	return ret;
+}
+
+static void untag_chunk(struct audit_chunk *chunk, struct fsnotify_mark *mark)
+{
+	struct audit_chunk *new;
+	int size;
+
+	fsnotify_group_lock(audit_tree_group);
+	/*
+	 * mark_mutex stabilizes chunk attached to the mark so we can check
+	 * whether it didn't change while we've dropped hash_lock.
+	 */
+	if (!(mark->flags & FSNOTIFY_MARK_FLAG_ATTACHED) ||
+	    mark_chunk(mark) != chunk)
+		goto out_mutex;
+
+	size = chunk_count_trees(chunk);
+	if (!size) {
+		spin_lock(&hash_lock);
+		list_del_init(&chunk->trees);
+		list_del_rcu(&chunk->hash);
+		replace_mark_chunk(mark, NULL);
+		spin_unlock(&hash_lock);
+		fsnotify_detach_mark(mark);
+		fsnotify_group_unlock(audit_tree_group);
+		audit_mark_put_chunk(chunk);
+		fsnotify_free_mark(mark);
+		return;
+	}
+
+	new = alloc_chunk(size);
+	if (!new)
+		goto out_mutex;
+
+	spin_lock(&hash_lock);
+	/*
+	 * This has to go last when updating chunk as once replace_chunk() is
+	 * called, new RCU readers can see the new chunk.
+	 */
+	replace_chunk(new, chunk);
+	spin_unlock(&hash_lock);
+	fsnotify_group_unlock(audit_tree_group);
+	audit_mark_put_chunk(chunk);
+	return;
+
+out_mutex:
+	fsnotify_group_unlock(audit_tree_group);
+}
+
+/* Call with group->mark_mutex held, releases it */
+static int create_chunk(struct inode *inode, struct audit_tree *tree)
+{
+	struct fsnotify_mark *mark;
+	struct audit_chunk *chunk = alloc_chunk(1);
+
+	if (!chunk) {
+		fsnotify_group_unlock(audit_tree_group);
+		return -ENOMEM;
+	}
+
+	mark = alloc_mark();
+	if (!mark) {
+		fsnotify_group_unlock(audit_tree_group);
+		kfree(chunk);
+		return -ENOMEM;
+	}
+
+	if (fsnotify_add_inode_mark_locked(mark, inode, 0)) {
+		fsnotify_group_unlock(audit_tree_group);
+		fsnotify_put_mark(mark);
+		kfree(chunk);
+		return -ENOSPC;
+	}
+
+	spin_lock(&hash_lock);
+	if (tree->goner) {
+		spin_unlock(&hash_lock);
+		fsnotify_detach_mark(mark);
+		fsnotify_group_unlock(audit_tree_group);
+		fsnotify_free_mark(mark);
+		fsnotify_put_mark(mark);
+		kfree(chunk);
+		return 0;
+	}
+	replace_mark_chunk(mark, chunk);
+	chunk->owners[0].index = (1U << 31);
+	chunk->owners[0].owner = tree;
+	get_tree(tree);
+	list_add(&chunk->owners[0].list, &tree->chunks);
+	if (!tree->root) {
+		tree->root = chunk;
+		list_add(&tree->same_root, &chunk->trees);
+	}
+	chunk->key = inode_to_key(inode);
+	/*
+	 * Inserting into the hash table has to go last as once we do that RCU
+	 * readers can see the chunk.
+	 */
+	insert_hash(chunk);
+	spin_unlock(&hash_lock);
+	fsnotify_group_unlock(audit_tree_group);
+	/*
+	 * Drop our initial reference. When mark we point to is getting freed,
+	 * we get notification through ->freeing_mark callback and cleanup
+	 * chunk pointing to this mark.
+	 */
+	fsnotify_put_mark(mark);
+	return 0;
+}
+
+/* the first tagged inode becomes root of tree */
+static int tag_chunk(struct inode *inode, struct audit_tree *tree)
+{
+	struct fsnotify_mark *mark;
+	struct audit_chunk *chunk, *old;
+	struct audit_node *p;
+	int n;
+
+	fsnotify_group_lock(audit_tree_group);
+	mark = fsnotify_find_mark(&inode->i_fsnotify_marks, audit_tree_group);
+	if (!mark)
+		return create_chunk(inode, tree);
+
+	/*
+	 * Found mark is guaranteed to be attached and mark_mutex protects mark
+	 * from getting detached and thus it makes sure there is chunk attached
+	 * to the mark.
+	 */
+	/* are we already there? */
+	spin_lock(&hash_lock);
+	old = mark_chunk(mark);
+	for (n = 0; n < old->count; n++) {
+		if (old->owners[n].owner == tree) {
+			spin_unlock(&hash_lock);
+			fsnotify_group_unlock(audit_tree_group);
+			fsnotify_put_mark(mark);
+			return 0;
+		}
+	}
+	spin_unlock(&hash_lock);
+
+	chunk = alloc_chunk(old->count + 1);
+	if (!chunk) {
+		fsnotify_group_unlock(audit_tree_group);
+		fsnotify_put_mark(mark);
+		return -ENOMEM;
+	}
+
+	spin_lock(&hash_lock);
+	if (tree->goner) {
+		spin_unlock(&hash_lock);
+		fsnotify_group_unlock(audit_tree_group);
+		fsnotify_put_mark(mark);
+		kfree(chunk);
+		return 0;
+	}
+	p = &chunk->owners[chunk->count - 1];
+	p->index = (chunk->count - 1) | (1U<<31);
+	p->owner = tree;
+	get_tree(tree);
+	list_add(&p->list, &tree->chunks);
+	if (!tree->root) {
+		tree->root = chunk;
+		list_add(&tree->same_root, &chunk->trees);
+	}
+	/*
+	 * This has to go last when updating chunk as once replace_chunk() is
+	 * called, new RCU readers can see the new chunk.
+	 */
+	replace_chunk(chunk, old);
+	spin_unlock(&hash_lock);
+	fsnotify_group_unlock(audit_tree_group);
+	fsnotify_put_mark(mark); /* pair to fsnotify_find_mark */
+	audit_mark_put_chunk(old);
+
+	return 0;
+}
+
+static void audit_tree_log_remove_rule(struct audit_context *context,
+				       struct audit_krule *rule)
+{
+	struct audit_buffer *ab;
+
+	if (!audit_enabled)
+		return;
+	ab = audit_log_start(context, GFP_KERNEL, AUDIT_CONFIG_CHANGE);
+	if (unlikely(!ab))
+		return;
+	audit_log_format(ab, "op=remove_rule dir=");
+	audit_log_untrustedstring(ab, rule->tree->pathname);
+	audit_log_key(ab, rule->filterkey);
+	audit_log_format(ab, " list=%d res=1", rule->listnr);
+	audit_log_end(ab);
+}
+
+static void kill_rules(struct audit_context *context, struct audit_tree *tree)
+{
+	struct audit_krule *rule, *next;
+	struct audit_entry *entry;
+
+	list_for_each_entry_safe(rule, next, &tree->rules, rlist) {
+		entry = container_of(rule, struct audit_entry, rule);
+
+		list_del_init(&rule->rlist);
+		if (rule->tree) {
+			/* not a half-baked one */
+			audit_tree_log_remove_rule(context, rule);
+			if (entry->rule.exe)
+				audit_remove_mark(entry->rule.exe);
+			rule->tree = NULL;
+			list_del_rcu(&entry->list);
+			list_del(&entry->rule.list);
+			call_rcu(&entry->rcu, audit_free_rule_rcu);
+		}
+	}
+}
+
+/*
+ * Remove tree from chunks. If 'tagged' is set, remove tree only from tagged
+ * chunks. The function expects tagged chunks are all at the beginning of the
+ * chunks list.
+ */
+static void prune_tree_chunks(struct audit_tree *victim, bool tagged)
+{
+	spin_lock(&hash_lock);
+	while (!list_empty(&victim->chunks)) {
+		struct audit_node *p;
+		struct audit_chunk *chunk;
+		struct fsnotify_mark *mark;
+
+		p = list_first_entry(&victim->chunks, struct audit_node, list);
+		/* have we run out of marked? */
+		if (tagged && !(p->index & (1U<<31)))
+			break;
+		chunk = find_chunk(p);
+		mark = chunk->mark;
+		remove_chunk_node(chunk, p);
+		/* Racing with audit_tree_freeing_mark()? */
+		if (!mark)
+			continue;
+		fsnotify_get_mark(mark);
+		spin_unlock(&hash_lock);
+
+		untag_chunk(chunk, mark);
+		fsnotify_put_mark(mark);
+
+		spin_lock(&hash_lock);
+	}
+	spin_unlock(&hash_lock);
+}
+
+/*
+ * finish killing struct audit_tree
+ */
+static void prune_one(struct audit_tree *victim)
+{
+	prune_tree_chunks(victim, false);
+	put_tree(victim);
+}
+
+/* trim the uncommitted chunks from tree */
+
+static void trim_marked(struct audit_tree *tree)
+{
+	struct list_head *p, *q;
+	spin_lock(&hash_lock);
+	if (tree->goner) {
+		spin_unlock(&hash_lock);
+		return;
+	}
+	/* reorder */
+	for (p = tree->chunks.next; p != &tree->chunks; p = q) {
+		struct audit_node *node = list_entry(p, struct audit_node, list);
+		q = p->next;
+		if (node->index & (1U<<31)) {
+			list_del_init(p);
+			list_add(p, &tree->chunks);
+		}
+	}
+	spin_unlock(&hash_lock);
+
+	prune_tree_chunks(tree, true);
+
+	spin_lock(&hash_lock);
+	if (!tree->root && !tree->goner) {
+		tree->goner = 1;
+		spin_unlock(&hash_lock);
+		mutex_lock(&audit_filter_mutex);
+		kill_rules(audit_context(), tree);
+		list_del_init(&tree->list);
+		mutex_unlock(&audit_filter_mutex);
+		prune_one(tree);
+	} else {
+		spin_unlock(&hash_lock);
+	}
+}
+
+static void audit_schedule_prune(void);
+
+/* called with audit_filter_mutex */
+int audit_remove_tree_rule(struct audit_krule *rule)
+{
+	struct audit_tree *tree;
+	tree = rule->tree;
+	if (tree) {
+		spin_lock(&hash_lock);
+		list_del_init(&rule->rlist);
+		if (list_empty(&tree->rules) && !tree->goner) {
+			tree->root = NULL;
+			list_del_init(&tree->same_root);
+			tree->goner = 1;
+			list_move(&tree->list, &prune_list);
+			rule->tree = NULL;
+			spin_unlock(&hash_lock);
+			audit_schedule_prune();
+			return 1;
+		}
+		rule->tree = NULL;
+		spin_unlock(&hash_lock);
+		return 1;
+	}
+	return 0;
+}
+
+static int compare_root(struct vfsmount *mnt, void *arg)
+{
+	return inode_to_key(d_backing_inode(mnt->mnt_root)) ==
+	       (unsigned long)arg;
+}
+
+void audit_trim_trees(void)
+{
+	struct list_head cursor;
+
+	mutex_lock(&audit_filter_mutex);
+	list_add(&cursor, &tree_list);
+	while (cursor.next != &tree_list) {
+		struct audit_tree *tree;
+		struct path path;
+		struct vfsmount *root_mnt;
+		struct audit_node *node;
+		int err;
+
+		tree = container_of(cursor.next, struct audit_tree, list);
+		get_tree(tree);
+		list_move(&cursor, &tree->list);
+		mutex_unlock(&audit_filter_mutex);
+
+		err = kern_path(tree->pathname, 0, &path);
+		if (err)
+			goto skip_it;
+
+		root_mnt = collect_mounts(&path);
+		path_put(&path);
+		if (IS_ERR(root_mnt))
+			goto skip_it;
+
+		spin_lock(&hash_lock);
+		list_for_each_entry(node, &tree->chunks, list) {
+			struct audit_chunk *chunk = find_chunk(node);
+			/* this could be NULL if the watch is dying else where... */
+			node->index |= 1U<<31;
+			if (iterate_mounts(compare_root,
+					   (void *)(chunk->key),
+					   root_mnt))
+				node->index &= ~(1U<<31);
+		}
+		spin_unlock(&hash_lock);
+		trim_marked(tree);
+		drop_collected_mounts(root_mnt);
+skip_it:
+		put_tree(tree);
+		mutex_lock(&audit_filter_mutex);
+	}
+	list_del(&cursor);
+	mutex_unlock(&audit_filter_mutex);
+}
+
+int audit_make_tree(struct audit_krule *rule, char *pathname, u32 op)
+{
+
+	if (pathname[0] != '/' ||
+	    (rule->listnr != AUDIT_FILTER_EXIT &&
+	     rule->listnr != AUDIT_FILTER_URING_EXIT) ||
+	    op != Audit_equal ||
+	    rule->inode_f || rule->watch || rule->tree)
+		return -EINVAL;
+	rule->tree = alloc_tree(pathname);
+	if (!rule->tree)
+		return -ENOMEM;
+	return 0;
+}
+
+void audit_put_tree(struct audit_tree *tree)
+{
+	put_tree(tree);
+}
+
+static int tag_mount(struct vfsmount *mnt, void *arg)
+{
+	return tag_chunk(d_backing_inode(mnt->mnt_root), 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 (;;) {
+		if (list_empty(&prune_list)) {
+			set_current_state(TASK_INTERRUPTIBLE);
+			schedule();
+		}
+
+		audit_ctl_lock();
+		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);
+		audit_ctl_unlock();
+	}
+	return 0;
+}
+
+static int audit_launch_prune(void)
+{
+	if (prune_thread)
+		return 0;
+	prune_thread = kthread_run(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;
+	}
+	return 0;
+}
+
+/* called with audit_filter_mutex */
+int audit_add_tree_rule(struct audit_krule *rule)
+{
+	struct audit_tree *seed = rule->tree, *tree;
+	struct path path;
+	struct vfsmount *mnt;
+	int err;
+
+	rule->tree = NULL;
+	list_for_each_entry(tree, &tree_list, list) {
+		if (!strcmp(seed->pathname, tree->pathname)) {
+			put_tree(seed);
+			rule->tree = tree;
+			list_add(&rule->rlist, &tree->rules);
+			return 0;
+		}
+	}
+	tree = seed;
+	list_add(&tree->list, &tree_list);
+	list_add(&rule->rlist, &tree->rules);
+	/* 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;
+	mnt = collect_mounts(&path);
+	path_put(&path);
+	if (IS_ERR(mnt)) {
+		err = PTR_ERR(mnt);
+		goto Err;
+	}
+
+	get_tree(tree);
+	err = iterate_mounts(tag_mount, tree, mnt);
+	drop_collected_mounts(mnt);
+
+	if (!err) {
+		struct audit_node *node;
+		spin_lock(&hash_lock);
+		list_for_each_entry(node, &tree->chunks, list)
+			node->index &= ~(1U<<31);
+		spin_unlock(&hash_lock);
+	} else {
+		trim_marked(tree);
+		goto Err;
+	}
+
+	mutex_lock(&audit_filter_mutex);
+	if (list_empty(&rule->rlist)) {
+		put_tree(tree);
+		return -ENOENT;
+	}
+	rule->tree = tree;
+	put_tree(tree);
+
+	return 0;
+Err:
+	mutex_lock(&audit_filter_mutex);
+	list_del_init(&tree->list);
+	list_del_init(&tree->rules);
+	put_tree(tree);
+	return err;
+}
+
+int audit_tag_tree(char *old, char *new)
+{
+	struct list_head cursor, barrier;
+	int failed = 0;
+	struct path path1, path2;
+	struct vfsmount *tagged;
+	int err;
+
+	err = kern_path(new, 0, &path2);
+	if (err)
+		return err;
+	tagged = collect_mounts(&path2);
+	path_put(&path2);
+	if (IS_ERR(tagged))
+		return PTR_ERR(tagged);
+
+	err = kern_path(old, 0, &path1);
+	if (err) {
+		drop_collected_mounts(tagged);
+		return err;
+	}
+
+	mutex_lock(&audit_filter_mutex);
+	list_add(&barrier, &tree_list);
+	list_add(&cursor, &barrier);
+
+	while (cursor.next != &tree_list) {
+		struct audit_tree *tree;
+		int good_one = 0;
+
+		tree = container_of(cursor.next, struct audit_tree, list);
+		get_tree(tree);
+		list_move(&cursor, &tree->list);
+		mutex_unlock(&audit_filter_mutex);
+
+		err = kern_path(tree->pathname, 0, &path2);
+		if (!err) {
+			good_one = path_is_under(&path1, &path2);
+			path_put(&path2);
+		}
+
+		if (!good_one) {
+			put_tree(tree);
+			mutex_lock(&audit_filter_mutex);
+			continue;
+		}
+
+		failed = iterate_mounts(tag_mount, tree, tagged);
+		if (failed) {
+			put_tree(tree);
+			mutex_lock(&audit_filter_mutex);
+			break;
+		}
+
+		mutex_lock(&audit_filter_mutex);
+		spin_lock(&hash_lock);
+		if (!tree->goner) {
+			list_move(&tree->list, &tree_list);
+		}
+		spin_unlock(&hash_lock);
+		put_tree(tree);
+	}
+
+	while (barrier.prev != &tree_list) {
+		struct audit_tree *tree;
+
+		tree = container_of(barrier.prev, struct audit_tree, list);
+		get_tree(tree);
+		list_move(&tree->list, &barrier);
+		mutex_unlock(&audit_filter_mutex);
+
+		if (!failed) {
+			struct audit_node *node;
+			spin_lock(&hash_lock);
+			list_for_each_entry(node, &tree->chunks, list)
+				node->index &= ~(1U<<31);
+			spin_unlock(&hash_lock);
+		} else {
+			trim_marked(tree);
+		}
+
+		put_tree(tree);
+		mutex_lock(&audit_filter_mutex);
+	}
+	list_del(&barrier);
+	list_del(&cursor);
+	mutex_unlock(&audit_filter_mutex);
+	path_put(&path1);
+	drop_collected_mounts(tagged);
+	return failed;
+}
+
+
+static void audit_schedule_prune(void)
+{
+	wake_up_process(prune_thread);
+}
+
+/*
+ * ... and that one is done if evict_chunk() decides to delay until the end
+ * of syscall.  Runs synchronously.
+ */
+void audit_kill_trees(struct audit_context *context)
+{
+	struct list_head *list = &context->killed_trees;
+
+	audit_ctl_lock();
+	mutex_lock(&audit_filter_mutex);
+
+	while (!list_empty(list)) {
+		struct audit_tree *victim;
+
+		victim = list_entry(list->next, struct audit_tree, list);
+		kill_rules(context, victim);
+		list_del_init(&victim->list);
+
+		mutex_unlock(&audit_filter_mutex);
+
+		prune_one(victim);
+
+		mutex_lock(&audit_filter_mutex);
+	}
+
+	mutex_unlock(&audit_filter_mutex);
+	audit_ctl_unlock();
+}
+
+/*
+ *  Here comes the stuff asynchronous to auditctl operations
+ */
+
+static void evict_chunk(struct audit_chunk *chunk)
+{
+	struct audit_tree *owner;
+	struct list_head *postponed = audit_killed_trees();
+	int need_prune = 0;
+	int n;
+
+	mutex_lock(&audit_filter_mutex);
+	spin_lock(&hash_lock);
+	while (!list_empty(&chunk->trees)) {
+		owner = list_entry(chunk->trees.next,
+				   struct audit_tree, same_root);
+		owner->goner = 1;
+		owner->root = NULL;
+		list_del_init(&owner->same_root);
+		spin_unlock(&hash_lock);
+		if (!postponed) {
+			kill_rules(audit_context(), owner);
+			list_move(&owner->list, &prune_list);
+			need_prune = 1;
+		} else {
+			list_move(&owner->list, postponed);
+		}
+		spin_lock(&hash_lock);
+	}
+	list_del_rcu(&chunk->hash);
+	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();
+}
+
+static int audit_tree_handle_event(struct fsnotify_mark *mark, u32 mask,
+				   struct inode *inode, struct inode *dir,
+				   const struct qstr *file_name, u32 cookie)
+{
+	return 0;
+}
+
+static void audit_tree_freeing_mark(struct fsnotify_mark *mark,
+				    struct fsnotify_group *group)
+{
+	struct audit_chunk *chunk;
+
+	fsnotify_group_lock(mark->group);
+	spin_lock(&hash_lock);
+	chunk = mark_chunk(mark);
+	replace_mark_chunk(mark, NULL);
+	spin_unlock(&hash_lock);
+	fsnotify_group_unlock(mark->group);
+	if (chunk) {
+		evict_chunk(chunk);
+		audit_mark_put_chunk(chunk);
+	}
+
+	/*
+	 * We are guaranteed to have at least one reference to the mark from
+	 * either the inode or the caller of fsnotify_destroy_mark().
+	 */
+	BUG_ON(refcount_read(&mark->refcnt) < 1);
+}
+
+static const struct fsnotify_ops audit_tree_ops = {
+	.handle_inode_event = audit_tree_handle_event,
+	.freeing_mark = audit_tree_freeing_mark,
+	.free_mark = audit_tree_destroy_watch,
+};
+
+static int __init audit_tree_init(void)
+{
+	int i;
+
+	audit_tree_mark_cachep = KMEM_CACHE(audit_tree_mark, SLAB_PANIC);
+
+	audit_tree_group = fsnotify_alloc_group(&audit_tree_ops, 0);
+	if (IS_ERR(audit_tree_group))
+		audit_panic("cannot initialize fsnotify group for rectree watches");
+
+	for (i = 0; i < HASH_SIZE; i++)
+		INIT_LIST_HEAD(&chunk_hash_heads[i]);
+
+	return 0;
+}
+__initcall(audit_tree_init);