diff options
| author | Florian Westphal <fw@strlen.de> | 2024-08-07 21:28:41 +0200 |
|---|---|---|
| committer | Pablo Neira Ayuso <pablo@netfilter.org> | 2024-08-14 23:37:23 +0200 |
| commit | 7d8dc1c7be8d3509e8f5164dd5df64c8e34d7eeb (patch) | |
| tree | 6c9e46a8826f58e13a337aaa9974df82e610d491 /net/bridge | |
| parent | e9767137308daf906496613fd879808a07f006a2 (diff) | |
netfilter: nf_queue: drop packets with cloned unconfirmed conntracks
Conntrack assumes an unconfirmed entry (not yet committed to global hash
table) has a refcount of 1 and is not visible to other cores.
With multicast forwarding this assumption breaks down because such
skbs get cloned after being picked up, i.e. ct->use refcount is > 1.
Likewise, bridge netfilter will clone broad/mutlicast frames and
all frames in case they need to be flood-forwarded during learning
phase.
For ip multicast forwarding or plain bridge flood-forward this will
"work" because packets don't leave softirq and are implicitly
serialized.
With nfqueue this no longer holds true, the packets get queued
and can be reinjected in arbitrary ways.
Disable this feature, I see no other solution.
After this patch, nfqueue cannot queue packets except the last
multicast/broadcast packet.
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Diffstat (limited to 'net/bridge')
| -rw-r--r-- | net/bridge/br_netfilter_hooks.c | 6 |
1 files changed, 5 insertions, 1 deletions
diff --git a/net/bridge/br_netfilter_hooks.c b/net/bridge/br_netfilter_hooks.c index 09f6a773a708..8f9c19d992ac 100644 --- a/net/bridge/br_netfilter_hooks.c +++ b/net/bridge/br_netfilter_hooks.c @@ -622,8 +622,12 @@ static unsigned int br_nf_local_in(void *priv, if (likely(nf_ct_is_confirmed(ct))) return NF_ACCEPT; + if (WARN_ON_ONCE(refcount_read(&nfct->use) != 1)) { + nf_reset_ct(skb); + return NF_ACCEPT; + } + WARN_ON_ONCE(skb_shared(skb)); - WARN_ON_ONCE(refcount_read(&nfct->use) != 1); /* We can't call nf_confirm here, it would create a dependency * on nf_conntrack module. |