linux-kernel - [PATCH 5.4 150/191] netfilter: nf_queue: enqueue skbs with NULL dst

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Message-Id: <20200107205340.996503436@linuxfoundation.org>
Date:   Tue,  7 Jan 2020 21:54:30 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Marco Oliverio <marco.oliverio@...aza.com>,
        Rocco Folino <rocco.folino@...aza.com>,
        Florian Westphal <fw@...len.de>,
        Pablo Neira Ayuso <pablo@...filter.org>
Subject: [PATCH 5.4 150/191] netfilter: nf_queue: enqueue skbs with NULL dst

From: Marco Oliverio <marco.oliverio@...aza.com>

commit 0b9173f4688dfa7c5d723426be1d979c24ce3d51 upstream.

Bridge packets that are forwarded have skb->dst == NULL and get
dropped by the check introduced by
b60a77386b1d4868f72f6353d35dabe5fbe981f2 (net: make skb_dst_force
return true when dst is refcounted).

To fix this we check skb_dst() before skb_dst_force(), so we don't
drop skb packet with dst == NULL. This holds also for skb at the
PRE_ROUTING hook so we remove the second check.

Fixes: b60a77386b1d ("net: make skb_dst_force return true when dst is refcounted")
Signed-off-by: Marco Oliverio <marco.oliverio@...aza.com>
Signed-off-by: Rocco Folino <rocco.folino@...aza.com>
Acked-by: Florian Westphal <fw@...len.de>
Signed-off-by: Pablo Neira Ayuso <pablo@...filter.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 net/netfilter/nf_queue.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/net/netfilter/nf_queue.c
+++ b/net/netfilter/nf_queue.c
@@ -189,7 +189,7 @@ static int __nf_queue(struct sk_buff *sk
 		goto err;
 	}
 
-	if (!skb_dst_force(skb) && state->hook != NF_INET_PRE_ROUTING) {
+	if (skb_dst(skb) && !skb_dst_force(skb)) {
 		status = -ENETDOWN;
 		goto err;
 	}