Re: [PATCH 10/10] audit: Replace chunk attached to mark instead of replacing mark

Audit tree code currently associates new fsnotify mark with each new chunk. As chunk attached to an inode is replaced when new tag is added / removed, we also need to remove old fsnotify mark and add a new one on such occasion. This is cumbersome and makes locking rules somewhat difficult to follow. Fix these problems by allocating fsnotify mark independently of chunk and keeping it all the time while there is some chunk attached to an inode. Also add documentation about the locking rules so that things are easier to follow. Signed-off-by: Jan Kara <jack(a)suse.cz&gt; --- kernel/audit_tree.c | 163 +++++++++++++++++++++++++++------------------------- 1 file changed, 85 insertions(+), 78 deletions(-)

diff --git a/kernel/audit_tree.c b/kernel/audit_tree.c index aec9b27a20ff..40f61de77dd0 100644 --- a/kernel/audit_tree.c +++ b/kernel/audit_tree.c @@ -272,6 +273,20 @@ static struct audit_chunk *find_chunk(struct node *p) return container_of(p, struct audit_chunk, owners[0]); } +static void replace_mark_chunk(struct fsnotify_mark *entry, + struct audit_chunk *chunk) +{ + struct audit_chunk *old; + + assert_spin_locked(&hash_lock); + old = AUDIT_M(entry)->chunk; + AUDIT_M(entry)->chunk = chunk; + if (chunk) + chunk->mark = entry; + if (old) + old->mark = NULL;

@@ -321,29 +341,31 @@ static void untag_chunk(struct node *p) mutex_lock(&entry->group->mark_mutex); /* - * mark_mutex protects mark from getting detached and thus also from - * mark->connector->obj getting NULL. + * mark_mutex protects mark stabilizes chunk attached to the mark so we + * can check whether it didn't change while we've dropped hash_lock.

*/ - if (chunk->dead || !(entry->flags & FSNOTIFY_MARK_FLAG_ATTACHED)) { + if (!(entry->flags & FSNOTIFY_MARK_FLAG_ATTACHED) || + AUDIT_M(entry)->chunk != chunk) { mutex_unlock(&entry->group->mark_mutex); if (new) - fsnotify_put_mark(new->mark); + kfree(new);