From: Florian Westphal fw@strlen.de
[ Upstream commit 2b272bb558f1d3a5aa95ed8a82253786fd1a48ba ]
When using a xfrm interface in a bridged setup (the outgoing device is bridged), the incoming packets in the xfrm interface are only tracked in the outgoing direction.
$ brctl show bridge name interfaces br_eth1 eth1
$ conntrack -L tcp 115 SYN_SENT src=192... dst=192... [UNREPLIED] ...
If br_netfilter is enabled, the first (encrypted) packet is received onR eth1, conntrack hooks are called from br_netfilter emulation which allocates nf_bridge info for this skb.
If the packet is for local machine, skb gets passed up the ip stack. The skb passes through ip prerouting a second time. br_netfilter ip_sabotage_in supresses the re-invocation of the hooks.
After this, skb gets decrypted in xfrm layer and appears in network stack a second time (after decryption).
Then, ip_sabotage_in is called again and suppresses netfilter hook invocation, even though the bridge layer never called them for the plaintext incarnation of the packet.
Free the bridge info after the first suppression to avoid this.
I was unable to figure out where the regression comes from, as far as i can see br_netfilter always had this problem; i did not expect that skb is looped again with different headers.
Fixes: c4b0e771f906 ("netfilter: avoid using skb->nf_bridge directly") Reported-and-tested-by: Wolfgang Nothdurft wolfgang@linogate.de Signed-off-by: Florian Westphal fw@strlen.de Signed-off-by: Pablo Neira Ayuso pablo@netfilter.org Signed-off-by: Sasha Levin sashal@kernel.org --- net/bridge/br_netfilter_hooks.c | 1 + 1 file changed, 1 insertion(+)
diff --git a/net/bridge/br_netfilter_hooks.c b/net/bridge/br_netfilter_hooks.c index f20f4373ff40..9554abcfd5b4 100644 --- a/net/bridge/br_netfilter_hooks.c +++ b/net/bridge/br_netfilter_hooks.c @@ -871,6 +871,7 @@ static unsigned int ip_sabotage_in(void *priv, if (nf_bridge && !nf_bridge->in_prerouting && !netif_is_l3_master(skb->dev) && !netif_is_l3_slave(skb->dev)) { + nf_bridge_info_free(skb); state->okfn(state->net, state->sk, skb); return NF_STOLEN; }