From 207b3ebacb6113acaaec0d171d5307032c690004 Mon Sep 17 00:00:00 2001 From: Florian Westphal Date: Thu, 20 Nov 2025 17:17:06 +0100 Subject: netfilter: nfnetlink_queue: do shared-unconfirmed check before segmentation Ulrich reports a regression with nfqueue: If an application did not set the 'F_GSO' capability flag and a gso packet with an unconfirmed nf_conn entry is received all packets are now dropped instead of queued, because the check happens after skb_gso_segment(). In that case, we did have exclusive ownership of the skb and its associated conntrack entry. The elevated use count is due to skb_clone happening via skb_gso_segment(). Move the check so that its peformed vs. the aggregated packet. Then, annotate the individual segments except the first one so we can do a 2nd check at reinject time. For the normal case, where userspace does in-order reinjects, this avoids packet drops: first reinjected segment continues traversal and confirms entry, remaining segments observe the confirmed entry. While at it, simplify nf_ct_drop_unconfirmed(): We only care about unconfirmed entries with a refcnt > 1, there is no need to special-case dying entries. This only happens with UDP. With TCP, the only unconfirmed packet will be the TCP SYN, those aren't aggregated by GRO. Next patch adds a udpgro test case to cover this scenario. Reported-by: Ulrich Weber Fixes: 7d8dc1c7be8d ("netfilter: nf_queue: drop packets with cloned unconfirmed conntracks") Signed-off-by: Florian Westphal --- include/net/netfilter/nf_queue.h | 1 + 1 file changed, 1 insertion(+) (limited to 'include') diff --git a/include/net/netfilter/nf_queue.h b/include/net/netfilter/nf_queue.h index e6803831d6af..45eb26b2e95b 100644 --- a/include/net/netfilter/nf_queue.h +++ b/include/net/netfilter/nf_queue.h @@ -21,6 +21,7 @@ struct nf_queue_entry { struct net_device *physout; #endif struct nf_hook_state state; + bool nf_ct_is_unconfirmed; u16 size; /* sizeof(entry) + saved route keys */ u16 queue_num; -- cgit v1.2.3