From 8b361a1fbcaa540e7d18911087ca18e178a028c2 Mon Sep 17 00:00:00 2001 From: Florian Westphal Date: Tue, 14 Jan 2025 00:50:34 +0100 Subject: [PATCH] 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 Signed-off-by: Pablo Neira Ayuso Signed-off-by: Sasha Levin --- net/netfilter/nft_flow_offload.c | 16 +++++++++++----- 1 file changed, 11 insertions(+), 5 deletions(-) diff --git a/net/netfilter/nft_flow_offload.c b/net/netfilter/nft_flow_offload.c index 7a8707632a81..9d335aa58907 100644 --- a/net/netfilter/nft_flow_offload.c +++ b/net/netfilter/nft_flow_offload.c @@ -288,6 +288,15 @@ 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) @@ -355,11 +364,8 @@ 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)