linux-kernel - [PATCH v2] net: ip6: ndisc: fix incorrect forwarding of proxied ns packets

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Message-ID: <20240815151809.16820-2-nils@nilsfuhler.de>
Date: Thu, 15 Aug 2024 17:18:10 +0200
From: Nils Fuhler <nils@...sfuhler.de>
To: davem@...emloft.net,
	dsahern@...nel.org,
	edumazet@...gle.com,
	kuba@...nel.org,
	pabeni@...hat.com
Cc: netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Nils Fuhler <nils@...sfuhler.de>
Subject: [PATCH v2] net: ip6: ndisc: fix incorrect forwarding of proxied ns packets

When enabling proxy_ndp per interface instead of globally, neighbor
solicitation packets sent to proxied global unicast addresses are
forwarded instead of generating a neighbor advertisement. When
proxy_ndp is enabled globally, these packets generate na responses as
expected.

This patch fixes this behaviour. When an ns packet is sent to a
proxied unicast address, it generates an na response regardless
whether proxy_ndp is enabled per interface or globally.

Signed-off-by: Nils Fuhler <nils@...sfuhler.de>
---
v1 -> v2: ensure that idev is not NULL

 net/ipv6/ip6_output.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
index ab504d31f0cd..0356c8189e21 100644
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -551,8 +551,8 @@ int ip6_forward(struct sk_buff *skb)
 		return -ETIMEDOUT;
 	}
 
-	/* XXX: idev->cnf.proxy_ndp? */
-	if (READ_ONCE(net->ipv6.devconf_all->proxy_ndp) &&
+	if ((READ_ONCE(net->ipv6.devconf_all->proxy_ndp) ||
+	     (idev && READ_ONCE(idev->cnf.proxy_ndp))) &&
 	    pneigh_lookup(&nd_tbl, net, &hdr->daddr, skb->dev, 0)) {
 		int proxied = ip6_forward_proxy_check(skb);
 		if (proxied > 0) {
-- 
2.39.2