From 2954fe60e33da0f4de4d81a4c95c7dddb517d00c Mon Sep 17 00:00:00 2001 From: Florian Westphal Date: Wed, 1 Feb 2023 14:45:22 +0100 Subject: netfilter: let reset rules clean out conntrack entries iptables/nftables support responding to tcp packets with tcp resets. The generated tcp reset packet passes through both output and postrouting netfilter hooks, but conntrack will never see them because the generated skb has its ->nfct pointer copied over from the packet that triggered the reset rule. If the reset rule is used for established connections, this may result in the conntrack entry to be around for a very long time (default timeout is 5 days). One way to avoid this would be to not copy the nf_conn pointer so that the rest packet passes through conntrack too. Problem is that output rules might not have the same conntrack zone setup as the prerouting ones, so its possible that the reset skb won't find the correct entry. Generating a template entry for the skb seems error prone as well. Add an explicit "closing" function that switches a confirmed conntrack entry to closed state and wire this up for tcp. If the entry isn't confirmed, no action is needed because the conntrack entry will never be committed to the table. Reported-by: Russel King Signed-off-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso --- net/ipv6/netfilter/nf_reject_ipv6.c | 1 + 1 file changed, 1 insertion(+) (limited to 'net/ipv6') diff --git a/net/ipv6/netfilter/nf_reject_ipv6.c b/net/ipv6/netfilter/nf_reject_ipv6.c index f61d4f18e1cf..58ccdb08c0fd 100644 --- a/net/ipv6/netfilter/nf_reject_ipv6.c +++ b/net/ipv6/netfilter/nf_reject_ipv6.c @@ -345,6 +345,7 @@ void nf_send_reset6(struct net *net, struct sock *sk, struct sk_buff *oldskb, nf_reject_ip6_tcphdr_put(nskb, oldskb, otcph, otcplen); nf_ct_attach(nskb, oldskb); + nf_ct_set_closing(skb_nfct(oldskb)); #if IS_ENABLED(CONFIG_BRIDGE_NETFILTER) /* If we use ip6_local_out for bridged traffic, the MAC source on -- cgit v1.2.1