From: Jan Kara <jack@suse.cz>
To: linux-audit@redhat.com
Cc: Paul Moore <paul@paul-moore.com>, <linux-fsdevel@vger.kernel.org>,
Al Viro <viro@ZenIV.linux.org.uk>,
Richard Guy Briggs <rgb@redhat.com>, Jan Kara <jack@suse.cz>
Subject: [PATCH 1/6] audit_tree: Replace mark->lock locking
Date: Thu, 28 Jun 2018 18:40:09 +0200 [thread overview]
Message-ID: <20180628164014.4925-2-jack@suse.cz> (raw)
In-Reply-To: <20180628164014.4925-1-jack@suse.cz>
Currently, audit_tree code uses mark->lock to protect against detaching
of mark from an inode. In most places it however also uses
mark->group->mark_mutex (as we need to atomically replace attached
marks) and this provides protection against mark detaching as well. So
just replace protection with mark->lock from audit tree code and replace
it with mark->group->mark_mutex protection in all the places. It
simplifies the code and gets rid of some ugly catches like calling
fsnotify_add_mark_locked() with mark->lock held (which cannot sleep only
because we hold a reference to another mark attached to the same inode).
Signed-off-by: Jan Kara <jack@suse.cz>
---
kernel/audit_tree.c | 24 ++++--------------------
1 file changed, 4 insertions(+), 20 deletions(-)
diff --git a/kernel/audit_tree.c b/kernel/audit_tree.c
index 02feef939560..1c82eb6674c4 100644
--- a/kernel/audit_tree.c
+++ b/kernel/audit_tree.c
@@ -193,7 +193,7 @@ static inline struct list_head *chunk_hash(unsigned long key)
return chunk_hash_heads + n % HASH_SIZE;
}
-/* hash_lock & entry->lock is held by caller */
+/* hash_lock & entry->group->mark_mutex is held by caller */
static void insert_hash(struct audit_chunk *chunk)
{
unsigned long key = chunk_to_key(chunk);
@@ -256,13 +256,11 @@ static void untag_chunk(struct node *p)
new = alloc_chunk(size);
mutex_lock(&entry->group->mark_mutex);
- spin_lock(&entry->lock);
/*
* mark_mutex protects mark from getting detached and thus also from
* mark->connector->obj getting NULL.
*/
if (chunk->dead || !(entry->flags & FSNOTIFY_MARK_FLAG_ATTACHED)) {
- spin_unlock(&entry->lock);
mutex_unlock(&entry->group->mark_mutex);
if (new)
fsnotify_put_mark(&new->mark);
@@ -280,7 +278,6 @@ static void untag_chunk(struct node *p)
list_del_init(&p->list);
list_del_rcu(&chunk->hash);
spin_unlock(&hash_lock);
- spin_unlock(&entry->lock);
mutex_unlock(&entry->group->mark_mutex);
fsnotify_destroy_mark(entry, audit_tree_group);
goto out;
@@ -323,7 +320,6 @@ static void untag_chunk(struct node *p)
list_for_each_entry(owner, &new->trees, same_root)
owner->root = new;
spin_unlock(&hash_lock);
- spin_unlock(&entry->lock);
mutex_unlock(&entry->group->mark_mutex);
fsnotify_destroy_mark(entry, audit_tree_group);
fsnotify_put_mark(&new->mark); /* drop initial reference */
@@ -340,7 +336,6 @@ static void untag_chunk(struct node *p)
p->owner = NULL;
put_tree(owner);
spin_unlock(&hash_lock);
- spin_unlock(&entry->lock);
mutex_unlock(&entry->group->mark_mutex);
out:
fsnotify_put_mark(entry);
@@ -360,12 +355,12 @@ static int create_chunk(struct inode *inode, struct audit_tree *tree)
return -ENOSPC;
}
- spin_lock(&entry->lock);
+ mutex_lock(&entry->group->mark_mutex);
spin_lock(&hash_lock);
if (tree->goner) {
spin_unlock(&hash_lock);
chunk->dead = 1;
- spin_unlock(&entry->lock);
+ mutex_unlock(&entry->group->mark_mutex);
fsnotify_destroy_mark(entry, audit_tree_group);
fsnotify_put_mark(entry);
return 0;
@@ -380,7 +375,7 @@ static int create_chunk(struct inode *inode, struct audit_tree *tree)
}
insert_hash(chunk);
spin_unlock(&hash_lock);
- spin_unlock(&entry->lock);
+ mutex_unlock(&entry->group->mark_mutex);
fsnotify_put_mark(entry); /* drop initial reference */
return 0;
}
@@ -421,14 +416,12 @@ static int tag_chunk(struct inode *inode, struct audit_tree *tree)
chunk_entry = &chunk->mark;
mutex_lock(&old_entry->group->mark_mutex);
- spin_lock(&old_entry->lock);
/*
* mark_mutex protects mark from getting detached and thus also from
* mark->connector->obj getting NULL.
*/
if (!(old_entry->flags & FSNOTIFY_MARK_FLAG_ATTACHED)) {
/* old_entry is being shot, lets just lie */
- spin_unlock(&old_entry->lock);
mutex_unlock(&old_entry->group->mark_mutex);
fsnotify_put_mark(old_entry);
fsnotify_put_mark(&chunk->mark);
@@ -437,23 +430,16 @@ static int tag_chunk(struct inode *inode, struct audit_tree *tree)
if (fsnotify_add_mark_locked(chunk_entry, old_entry->connector->obj,
FSNOTIFY_OBJ_TYPE_INODE, 1)) {
- spin_unlock(&old_entry->lock);
mutex_unlock(&old_entry->group->mark_mutex);
fsnotify_put_mark(chunk_entry);
fsnotify_put_mark(old_entry);
return -ENOSPC;
}
- /* even though we hold old_entry->lock, this is safe since chunk_entry->lock could NEVER have been grabbed before */
- spin_lock(&chunk_entry->lock);
spin_lock(&hash_lock);
-
- /* we now hold old_entry->lock, chunk_entry->lock, and hash_lock */
if (tree->goner) {
spin_unlock(&hash_lock);
chunk->dead = 1;
- spin_unlock(&chunk_entry->lock);
- spin_unlock(&old_entry->lock);
mutex_unlock(&old_entry->group->mark_mutex);
fsnotify_destroy_mark(chunk_entry, audit_tree_group);
@@ -485,8 +471,6 @@ static int tag_chunk(struct inode *inode, struct audit_tree *tree)
list_add(&tree->same_root, &chunk->trees);
}
spin_unlock(&hash_lock);
- spin_unlock(&chunk_entry->lock);
- spin_unlock(&old_entry->lock);
mutex_unlock(&old_entry->group->mark_mutex);
fsnotify_destroy_mark(old_entry, audit_tree_group);
fsnotify_put_mark(chunk_entry); /* drop initial reference */
--
2.16.4
next prev parent reply other threads:[~2018-06-28 19:03 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-06-28 16:40 [PATCH 0/6] audit: Fix various races when tagging and untagging mounts Jan Kara
2018-06-28 16:40 ` Jan Kara [this message]
2018-06-29 11:31 ` [PATCH 1/6] audit_tree: Replace mark->lock locking Amir Goldstein
2018-07-03 14:07 ` Jan Kara
2018-06-28 16:40 ` [PATCH 2/6] audit: Fix possible spurious -ENOSPC error Jan Kara
2018-06-29 11:42 ` Amir Goldstein
2018-07-02 6:05 ` Dan Carpenter
2018-07-03 14:18 ` Jan Kara
2018-06-28 16:40 ` [PATCH 3/6] audit: Fix possible tagging failures Jan Kara
2018-06-29 12:05 ` Amir Goldstein
2018-07-03 14:21 ` Jan Kara
2018-07-03 17:42 ` Amir Goldstein
2018-07-04 8:28 ` Jan Kara
2018-06-28 16:40 ` [PATCH 4/6] audit: Embed key into chunk Jan Kara
2018-06-29 12:53 ` Amir Goldstein
2018-07-03 14:25 ` Jan Kara
2018-06-28 16:40 ` [PATCH 5/6] audit: Make hash table insertion safe against concurrent lookups Jan Kara
2018-06-29 13:02 ` Amir Goldstein
2018-07-03 15:31 ` Jan Kara
2018-06-28 16:40 ` [PATCH 6/6] audit: Point to fsnotify mark instead of embedding it Jan Kara
2018-06-29 13:20 ` Amir Goldstein
2018-07-04 12:34 ` Jan Kara
2018-06-29 11:44 ` [PATCH 0/6] audit: Fix various races when tagging and untagging mounts Amir Goldstein
2018-06-29 18:01 ` Paul Moore
2018-07-03 14:14 ` Jan Kara
2018-07-03 17:03 ` Paul Moore
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20180628164014.4925-2-jack@suse.cz \
--to=jack@suse.cz \
--cc=linux-audit@redhat.com \
--cc=linux-fsdevel@vger.kernel.org \
--cc=paul@paul-moore.com \
--cc=rgb@redhat.com \
--cc=viro@ZenIV.linux.org.uk \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).