From 49a4ee7d98dbe34cfed90b930664c8a9fa73b24c Mon Sep 17 00:00:00 2001 From: Jan Kara Date: Mon, 12 Nov 2018 09:54:49 -0500 Subject: audit: Guarantee forward progress of chunk untagging When removing chunk from a tree, we do shrink the chunk. This can fail for various reasons (due to races, ENOMEM, etc.) and in some cases we just bail from untag_chunk() relying on someone else to cleanup. Although this currently works, later we will need to add new failure situation which would break. Also this simplifies the code and will allow us to make locking around untag_chunk() less awkward. Signed-off-by: Jan Kara Reviewed-by: Richard Guy Briggs Signed-off-by: Paul Moore --- kernel/audit_tree.c | 42 +++++++++++++++++------------------------- 1 file changed, 17 insertions(+), 25 deletions(-) diff --git a/kernel/audit_tree.c b/kernel/audit_tree.c index c98ab2d68a1c..ca2b6baff7aa 100644 --- a/kernel/audit_tree.c +++ b/kernel/audit_tree.c @@ -309,16 +309,28 @@ static void replace_chunk(struct audit_chunk *new, struct audit_chunk *old, list_replace_rcu(&old->hash, &new->hash); } +static void remove_chunk_node(struct audit_chunk *chunk, struct 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 void untag_chunk(struct node *p) { struct audit_chunk *chunk = find_chunk(p); struct fsnotify_mark *entry = chunk->mark; struct audit_chunk *new = NULL; - struct audit_tree *owner; int size = chunk->count - 1; + remove_chunk_node(chunk, p); fsnotify_get_mark(entry); - spin_unlock(&hash_lock); if (size) @@ -336,15 +348,10 @@ static void untag_chunk(struct node *p) goto out; } - owner = p->owner; - if (!size) { chunk->dead = 1; spin_lock(&hash_lock); list_del_init(&chunk->trees); - if (owner->root == chunk) - owner->root = NULL; - list_del_init(&p->list); list_del_rcu(&chunk->hash); spin_unlock(&hash_lock); fsnotify_detach_mark(entry); @@ -354,21 +361,16 @@ static void untag_chunk(struct node *p) } if (!new) - goto Fallback; + goto out_mutex; if (fsnotify_add_mark_locked(new->mark, entry->connector->obj, FSNOTIFY_OBJ_TYPE_INODE, 1)) { fsnotify_put_mark(new->mark); - goto Fallback; + goto out_mutex; } chunk->dead = 1; spin_lock(&hash_lock); - if (owner->root == chunk) { - list_del_init(&owner->same_root); - owner->root = NULL; - } - list_del_init(&p->list); /* * This has to go last when updating chunk as once replace_chunk() is * called, new RCU readers can see the new chunk. @@ -381,17 +383,7 @@ static void untag_chunk(struct node *p) fsnotify_put_mark(new->mark); /* drop initial reference */ goto out; -Fallback: - // do the best we can - spin_lock(&hash_lock); - if (owner->root == chunk) { - list_del_init(&owner->same_root); - owner->root = NULL; - } - list_del_init(&p->list); - p->owner = NULL; - put_tree(owner); - spin_unlock(&hash_lock); +out_mutex: mutex_unlock(&entry->group->mark_mutex); out: fsnotify_put_mark(entry); -- cgit v1.2.3