This is a note to let you know that I've just added the patch titled
netfilter: nft_flow_offload: update tcp state flags under lock
to the 5.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
netfilter-nft_flow_offload-update-tcp-state-flags-un.patch
and it can be found in the queue-5.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 1e3e5820139d182c38f5f07402c68fe48efaf8c3
Author: Florian Westphal <fw@xxxxxxxxx>
Date: Tue Jan 14 00:50:34 2025 +0100
netfilter: nft_flow_offload: update tcp state flags under lock
[ Upstream commit 7a4b61406395291ffb7220a10e8951a9a8684819 ]
The conntrack entry is already public, there is a small chance that another
CPU is handling a packet in reply direction and racing with the tcp state
update.
Move this under ct spinlock.
This is done once, when ct is about to be offloaded, so this should
not result in a noticeable performance hit.
Fixes: 8437a6209f76 ("netfilter: nft_flow_offload: set liberal tracking mode for tcp")
Signed-off-by: Florian Westphal <fw@xxxxxxxxx>
Signed-off-by: Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/net/netfilter/nft_flow_offload.c b/net/netfilter/nft_flow_offload.c
index fbb9f3a6c8444..41d04fa12f67d 100644
--- a/net/netfilter/nft_flow_offload.c
+++ b/net/netfilter/nft_flow_offload.c
@@ -278,6 +278,15 @@ static bool nft_flow_offload_skip(struct sk_buff *skb, int family)
return false;
}
+static void flow_offload_ct_tcp(struct nf_conn *ct)
+{
+ /* conntrack will not see all packets, disable tcp window validation. */
+ spin_lock_bh(&ct->lock);
+ ct->proto.tcp.seen[0].flags |= IP_CT_TCP_FLAG_BE_LIBERAL;
+ ct->proto.tcp.seen[1].flags |= IP_CT_TCP_FLAG_BE_LIBERAL;
+ spin_unlock_bh(&ct->lock);
+}
+
static void nft_flow_offload_eval(const struct nft_expr *expr,
struct nft_regs *regs,
const struct nft_pktinfo *pkt)
@@ -332,11 +341,8 @@ static void nft_flow_offload_eval(const struct nft_expr *expr,
goto err_flow_alloc;
flow_offload_route_init(flow, &route);
-
- if (tcph) {
- ct->proto.tcp.seen[0].flags |= IP_CT_TCP_FLAG_BE_LIBERAL;
- ct->proto.tcp.seen[1].flags |= IP_CT_TCP_FLAG_BE_LIBERAL;
- }
+ if (tcph)
+ flow_offload_ct_tcp(ct);
ret = flow_offload_add(flowtable, flow);
if (ret < 0)
