From: Eric Dumazet edumazet@google.com

commit 6f0012e35160cd08a53e46e3b3bbf724b92dfe68 upstream.

When the third packet of 3WHS connection establishment contains payload, it is added into socket receive queue without the XFRM check and the drop of connection tracking context.

This means that if the data is left unread in the socket receive queue, conntrack module can not be unloaded.

As most applications usually reads the incoming data immediately after accept(), bug has been hiding for quite a long time.

Commit 68822bdf76f1 ("net: generalize skb freeing deferral to per-cpu lists") exposed this bug because even if the application reads this data, the skb with nfct state could stay in a per-cpu cache for an arbitrary time, if said cpu no longer process RX softirqs.

Many thanks to Ilya Maximets for reporting this issue, and for testing various patches: https://lore.kernel.org/netdev/20220619003919.394622-1-i.maximets@ovn.org/

Note that I also added a missing xfrm4_policy_check() call, although this is probably not a big issue, as the SYN packet should have been dropped earlier.

Fixes: b59c270104f0 ("[NETFILTER]: Keep conntrack reference until IPsec policy checks are done") Reported-by: Ilya Maximets i.maximets@ovn.org Signed-off-by: Eric Dumazet edumazet@google.com Cc: Florian Westphal fw@strlen.de Cc: Pablo Neira Ayuso pablo@netfilter.org Cc: Steffen Klassert steffen.klassert@secunet.com Tested-by: Ilya Maximets i.maximets@ovn.org Reviewed-by: Ilya Maximets i.maximets@ovn.org Link: https://lore.kernel.org/r/20220623050436.1290307-1-edumazet@google.com Signed-off-by: Jakub Kicinski kuba@kernel.org --- net/ipv4/tcp_ipv4.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c index a189625098ba..5d94822fd506 100644 --- a/net/ipv4/tcp_ipv4.c +++ b/net/ipv4/tcp_ipv4.c @@ -2014,7 +2014,8 @@ int tcp_v4_rcv(struct sk_buff *skb) struct sock *nsk;

sk = req->rsk_listener; - if (unlikely(tcp_v4_inbound_md5_hash(sk, skb, dif, sdif))) { + if (unlikely(!xfrm4_policy_check(sk, XFRM_POLICY_IN, skb) || + tcp_v4_inbound_md5_hash(sk, skb, dif, sdif))) { sk_drops_add(sk, skb); reqsk_put(req); goto discard_it; @@ -2061,6 +2062,7 @@ int tcp_v4_rcv(struct sk_buff *skb) } goto discard_and_relse; } + nf_reset_ct(skb); if (nsk == sk) { reqsk_put(req); tcp_v4_restore_cb(skb);