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From: David Carlier <devnexen@gmail.com>
To: "David S . Miller" <davem@davemloft.net>,
	Eric Dumazet <edumazet@google.com>,
	Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
	Simon Horman <horms@kernel.org>,
	Herbert Xu <herbert@gondor.apana.org.au>
Cc: netdev@vger.kernel.org, stable@vger.kernel.org,
	David Carlier <devnexen@gmail.com>
Subject: [PATCH v2 1/2] net/sched: act_nat: fix inner IP header checksum in ICMP error packets
Date: Sat,  4 Apr 2026 13:03:09 +0100	[thread overview]
Message-ID: <20260404120310.88218-1-devnexen@gmail.com> (raw)

Update the inner IP header checksum when rewriting addresses
inside ICMP error payloads, matching netfilter's nf_nat_ipv4_manip_pkt()
behavior.

Fixes: b4219952356b ("[PKT_SCHED]: Add stateless NAT")
Cc: stable@vger.kernel.org
Signed-off-by: David Carlier <devnexen@gmail.com>
---
 net/sched/act_nat.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/net/sched/act_nat.c b/net/sched/act_nat.c
index abb332dee836..cd1d299da57c 100644
--- a/net/sched/act_nat.c
+++ b/net/sched/act_nat.c
@@ -242,7 +242,9 @@ TC_INDIRECT_SCOPE int tcf_nat_act(struct sk_buff *skb,
 		new_addr &= mask;
 		new_addr |= addr & ~mask;
 
-		/* XXX Fix up the inner checksums. */
+		/* Update inner IP header checksum after address rewrite */
+		csum_replace4(&iph->check, addr, new_addr);
+
 		if (egress)
 			iph->daddr = new_addr;
 		else
-- 
2.53.0


             reply	other threads:[~2026-04-04 12:03 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-04-04 12:03 David Carlier [this message]
2026-04-04 12:03 ` [PATCH v2 2/2] selftests: net: add act_nat ICMP inner checksum test David Carlier
2026-04-04 18:01   ` Jakub Kicinski

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