This is a note to let you know that I've just added the patch titled
netfilter: nf_tables: don't skip expired elements during walk
to the 5.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
netfilter-nf_tables-don-t-skip-expired-elements-during-walk.patch
and it can be found in the queue-5.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 24138933b97b055d486e8064b4a1721702442a9b Mon Sep 17 00:00:00 2001
From: Florian Westphal <fw@xxxxxxxxx>
Date: Wed, 9 Aug 2023 14:31:15 +0200
Subject: netfilter: nf_tables: don't skip expired elements during walk
From: Florian Westphal <fw@xxxxxxxxx>
commit 24138933b97b055d486e8064b4a1721702442a9b upstream.
There is an asymmetry between commit/abort and preparation phase if the
following conditions are met:
1. set is a verdict map ("1.2.3.4 : jump foo")
2. timeouts are enabled
In this case, following sequence is problematic:
1. element E in set S refers to chain C
2. userspace requests removal of set S
3. kernel does a set walk to decrement chain->use count for all elements
from preparation phase
4. kernel does another set walk to remove elements from the commit phase
(or another walk to do a chain->use increment for all elements from
abort phase)
If E has already expired in 1), it will be ignored during list walk, so its use count
won't have been changed.
Then, when set is culled, ->destroy callback will zap the element via
nf_tables_set_elem_destroy(), but this function is only safe for
elements that have been deactivated earlier from the preparation phase:
lack of earlier deactivate removes the element but leaks the chain use
count, which results in a WARN splat when the chain gets removed later,
plus a leak of the nft_chain structure.
Update pipapo_get() not to skip expired elements, otherwise flush
command reports bogus ENOENT errors.
Fixes: 3c4287f62044 ("nf_tables: Add set type for arbitrary concatenation of ranges")
Fixes: 8d8540c4f5e0 ("netfilter: nft_set_rbtree: add timeout support")
Fixes: 9d0982927e79 ("netfilter: nft_hash: add support for timeouts")
Signed-off-by: Florian Westphal <fw@xxxxxxxxx>
Signed-off-by: Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
net/netfilter/nf_tables_api.c | 4 ++++
net/netfilter/nft_set_hash.c | 2 --
net/netfilter/nft_set_pipapo.c | 18 ++++++++++++------
net/netfilter/nft_set_rbtree.c | 2 --
4 files changed, 16 insertions(+), 10 deletions(-)
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -5274,8 +5274,12 @@ static int nf_tables_dump_setelem(const
const struct nft_set_iter *iter,
struct nft_set_elem *elem)
{
+ const struct nft_set_ext *ext = nft_set_elem_ext(set, elem->priv);
struct nft_set_dump_args *args;
+ if (nft_set_elem_expired(ext))
+ return 0;
+
args = container_of(iter, struct nft_set_dump_args, iter);
return nf_tables_fill_setelem(args->skb, set, elem);
}
--- a/net/netfilter/nft_set_hash.c
+++ b/net/netfilter/nft_set_hash.c
@@ -278,8 +278,6 @@ static void nft_rhash_walk(const struct
if (iter->count < iter->skip)
goto cont;
- if (nft_set_elem_expired(&he->ext))
- goto cont;
if (!nft_set_elem_active(&he->ext, iter->genmask))
goto cont;
--- a/net/netfilter/nft_set_pipapo.c
+++ b/net/netfilter/nft_set_pipapo.c
@@ -566,8 +566,7 @@ next_match:
goto out;
if (last) {
- if (nft_set_elem_expired(&f->mt[b].e->ext) ||
- (genmask &&
+ if ((genmask &&
!nft_set_elem_active(&f->mt[b].e->ext, genmask)))
goto next_match;
@@ -601,8 +600,17 @@ out:
static void *nft_pipapo_get(const struct net *net, const struct nft_set *set,
const struct nft_set_elem *elem, unsigned int flags)
{
- return pipapo_get(net, set, (const u8 *)elem->key.val.data,
- nft_genmask_cur(net));
+ struct nft_pipapo_elem *ret;
+
+ ret = pipapo_get(net, set, (const u8 *)elem->key.val.data,
+ nft_genmask_cur(net));
+ if (IS_ERR(ret))
+ return ret;
+
+ if (nft_set_elem_expired(&ret->ext))
+ return ERR_PTR(-ENOENT);
+
+ return ret;
}
/**
@@ -2006,8 +2014,6 @@ static void nft_pipapo_walk(const struct
goto cont;
e = f->mt[r].e;
- if (nft_set_elem_expired(&e->ext))
- goto cont;
elem.priv = e;
--- a/net/netfilter/nft_set_rbtree.c
+++ b/net/netfilter/nft_set_rbtree.c
@@ -552,8 +552,6 @@ static void nft_rbtree_walk(const struct
if (iter->count < iter->skip)
goto cont;
- if (nft_set_elem_expired(&rbe->ext))
- goto cont;
if (!nft_set_elem_active(&rbe->ext, iter->genmask))
goto cont;
Patches currently in stable-queue which might be from fw@xxxxxxxxx are
queue-5.15/netfilter-nf_tables-don-t-skip-expired-elements-during-walk.patch
