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Commit d31b326d authored by Jan Kara's avatar Jan Kara Committed by Paul Moore
Browse files

audit: Factor out chunk replacement code 



Chunk replacement code is very similar for the cases where we grow or
shrink chunk. Factor the code out into a common helper function.

Signed-off-by: default avatarJan Kara <jack@suse.cz>
Reviewed-by: default avatarRichard Guy Briggs <rgb@redhat.com>
Signed-off-by: default avatarPaul Moore <paul@paul-moore.com>
parent 1635e572

kernel/audit_tree.c

+40 −46
Original line number Diff line number Diff line
@@ -235,6 +235,38 @@ static struct audit_chunk *find_chunk(struct node *p) 
	return container_of(p, struct audit_chunk, owners[0]);

}



static void replace_chunk(struct audit_chunk *new, struct audit_chunk *old,

			  struct node *skip)

{

	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] == skip) {

			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);

	}

	/*

	 * 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 untag_chunk(struct node *p)

{

	struct audit_chunk *chunk = find_chunk(p);
@@ -242,7 +274,6 @@ static void untag_chunk(struct node *p) 
	struct audit_chunk *new = NULL;

	struct audit_tree *owner;

	int size = chunk->count - 1;

	int i, j;



	fsnotify_get_mark(entry);
@@ -291,38 +322,16 @@ static void untag_chunk(struct node *p) 


	chunk->dead = 1;

	spin_lock(&hash_lock);

	new->key = chunk->key;

	list_replace_init(&chunk->trees, &new->trees);

	if (owner->root == chunk) {

		list_del_init(&owner->same_root);

		owner->root = NULL;

	}



	for (i = j = 0; j <= size; i++, j++) {

		struct audit_tree *s;

		if (&chunk->owners[j] == p) {

	list_del_init(&p->list);

			i--;

			continue;

		}

		s = chunk->owners[j].owner;

		new->owners[i].owner = s;

		new->owners[i].index = chunk->owners[j].index - j + i;

		if (!s) /* result of earlier fallback */

			continue;

		get_tree(s);

		list_replace_init(&chunk->owners[j].list, &new->owners[i].list);

	}



	list_for_each_entry(owner, &new->trees, same_root)

		owner->root = 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().

	 * This has to go last when updating chunk as once replace_chunk() is

	 * called, new RCU readers can see the new chunk.

	 */

	smp_wmb();

	list_replace_rcu(&chunk->hash, &new->hash);

	replace_chunk(new, chunk, p);

	spin_unlock(&hash_lock);

	fsnotify_detach_mark(entry);

	mutex_unlock(&entry->group->mark_mutex);
@@ -399,7 +408,6 @@ static int create_chunk(struct inode *inode, struct audit_tree *tree) 
static int tag_chunk(struct inode *inode, struct audit_tree *tree)

{

	struct fsnotify_mark *old_entry, *chunk_entry;

	struct audit_tree *owner;

	struct audit_chunk *chunk, *old;

	struct node *p;

	int n;
@@ -464,35 +472,21 @@ static int tag_chunk(struct inode *inode, struct audit_tree *tree) 
		fsnotify_put_mark(old_entry);

		return 0;

	}

	chunk->key = old->key;

	list_replace_init(&old->trees, &chunk->trees);

	for (n = 0, p = chunk->owners; n < old->count; n++, p++) {

		struct audit_tree *s = old->owners[n].owner;

		p->owner = s;

		p->index = old->owners[n].index;

		if (!s) /* result of fallback in untag */

			continue;

		get_tree(s);

		list_replace_init(&old->owners[n].list, &p->list);

	}

	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);

	list_for_each_entry(owner, &chunk->trees, same_root)

		owner->root = chunk;

	old->dead = 1;

	if (!tree->root) {

		tree->root = chunk;

		list_add(&tree->same_root, &chunk->trees);

	}

	/*

	 * 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().

	 * This has to go last when updating chunk as once replace_chunk() is

	 * called, new RCU readers can see the new chunk.

	 */

	smp_wmb();

	list_replace_rcu(&old->hash, &chunk->hash);

	replace_chunk(chunk, old, NULL);

	spin_unlock(&hash_lock);

	fsnotify_detach_mark(old_entry);

	mutex_unlock(&audit_tree_group->mark_mutex);