netdev - [PATCH net 1/5] netfilter: br_netfilter: fix recent physdev match breakage

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Date:   Tue, 18 Apr 2023 16:50:44 +0200
From:   Pablo Neira Ayuso <pablo@...filter.org>
To:     netfilter-devel@...r.kernel.org
Cc:     davem@...emloft.net, netdev@...r.kernel.org, kuba@...nel.org,
        pabeni@...hat.com, edumazet@...gle.com
Subject: [PATCH net 1/5] netfilter: br_netfilter: fix recent physdev match breakage

From: Florian Westphal <fw@...len.de>

Recent attempt to ensure PREROUTING hook is executed again when a
decrypted ipsec packet received on a bridge passes through the network
stack a second time broke the physdev match in INPUT hook.

We can't discard the nf_bridge info strct from sabotage_in hook, as
this is needed by the physdev match.

Keep the struct around and handle this with another conditional instead.

Fixes: 2b272bb558f1 ("netfilter: br_netfilter: disable sabotage_in hook after first suppression")
Reported-and-tested-by: Farid BENAMROUCHE <fariouche@...oo.fr>
Signed-off-by: Florian Westphal <fw@...len.de>
Signed-off-by: Pablo Neira Ayuso <pablo@...filter.org>
---
 include/linux/skbuff.h          |  1 +
 net/bridge/br_netfilter_hooks.c | 17 +++++++++++------
 2 files changed, 12 insertions(+), 6 deletions(-)

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index ff7ad331fb82..1ec3530c8191 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -294,6 +294,7 @@ struct nf_bridge_info {
 	u8			pkt_otherhost:1;
 	u8			in_prerouting:1;
 	u8			bridged_dnat:1;
+	u8			sabotage_in_done:1;
 	__u16			frag_max_size;
 	struct net_device	*physindev;
 
diff --git a/net/bridge/br_netfilter_hooks.c b/net/bridge/br_netfilter_hooks.c
index 638a4d5359db..4bc6761517bb 100644
--- a/net/bridge/br_netfilter_hooks.c
+++ b/net/bridge/br_netfilter_hooks.c
@@ -868,12 +868,17 @@ static unsigned int ip_sabotage_in(void *priv,
 {
 	struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb);
 
-	if (nf_bridge && !nf_bridge->in_prerouting &&
-	    !netif_is_l3_master(skb->dev) &&
-	    !netif_is_l3_slave(skb->dev)) {
-		nf_bridge_info_free(skb);
-		state->okfn(state->net, state->sk, skb);
-		return NF_STOLEN;
+	if (nf_bridge) {
+		if (nf_bridge->sabotage_in_done)
+			return NF_ACCEPT;
+
+		if (!nf_bridge->in_prerouting &&
+		    !netif_is_l3_master(skb->dev) &&
+		    !netif_is_l3_slave(skb->dev)) {
+			nf_bridge->sabotage_in_done = 1;
+			state->okfn(state->net, state->sk, skb);
+			return NF_STOLEN;
+		}
 	}
 
 	return NF_ACCEPT;
-- 
2.30.2