From: Florian Westphal Date: Mon, 13 Jan 2025 23:50:34 +0000 (+0100) Subject: netfilter: nft_flow_offload: update tcp state flags under lock X-Git-Tag: v6.14-rc1~162^2~7^2~4 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=7a4b61406395291ffb7220a10e8951a9a8684819;p=thirdparty%2Fkernel%2Flinux.git netfilter: nft_flow_offload: update tcp state flags under lock 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 --- diff --git a/net/netfilter/nft_flow_offload.c b/net/netfilter/nft_flow_offload.c index 3b474d2356638..221d502230181 100644 --- a/net/netfilter/nft_flow_offload.c +++ b/net/netfilter/nft_flow_offload.c @@ -289,6 +289,15 @@ 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) @@ -356,11 +365,8 @@ 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); __set_bit(NF_FLOW_HW_BIDIRECTIONAL, &flow->flags); ret = flow_offload_add(flowtable, flow);