From 6f0012e35160cd08a53e46e3b3bbf724b92dfe68 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Thu, 23 Jun 2022 05:04:36 +0000 Subject: [PATCH] tcp: add a missing nf_reset_ct() in 3WHS handling 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 Signed-off-by: Eric Dumazet Cc: Florian Westphal Cc: Pablo Neira Ayuso Cc: Steffen Klassert Tested-by: Ilya Maximets Reviewed-by: Ilya Maximets Link: https://lore.kernel.org/r/20220623050436.1290307-1-edumazet@google.com Signed-off-by: Jakub Kicinski --- net/ipv4/tcp_ipv4.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c index fe8f23b95d32c..da5a3c44c4fb7 100644 --- a/net/ipv4/tcp_ipv4.c +++ b/net/ipv4/tcp_ipv4.c @@ -1964,7 +1964,10 @@ process: struct sock *nsk; sk = req->rsk_listener; - drop_reason = tcp_inbound_md5_hash(sk, skb, + if (!xfrm4_policy_check(sk, XFRM_POLICY_IN, skb)) + drop_reason = SKB_DROP_REASON_XFRM_POLICY; + else + drop_reason = tcp_inbound_md5_hash(sk, skb, &iph->saddr, &iph->daddr, AF_INET, dif, sdif); if (unlikely(drop_reason)) { @@ -2016,6 +2019,7 @@ process: } goto discard_and_relse; } + nf_reset_ct(skb); if (nsk == sk) { reqsk_put(req); tcp_v4_restore_cb(skb); -- 2.39.5