linux-kernel - [PATCH 3.10 270/319] ipv4: Set skb->protocol properly for local output

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Message-Id: <1486322541-8206-171-git-send-email-w@1wt.eu>
Date:   Sun,  5 Feb 2017 20:21:32 +0100
From:   Willy Tarreau <w@....eu>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org,
        linux@...ck-us.net
Cc:     Eli Cooper <elicooper@....com>,
        "David S . Miller" <davem@...emloft.net>, Willy Tarreau <w@....eu>
Subject: [PATCH 3.10 270/319] ipv4: Set skb->protocol properly for local output

From: Eli Cooper <elicooper@....com>

commit f4180439109aa720774baafdd798b3234ab1a0d2 upstream.

When xfrm is applied to TSO/GSO packets, it follows this path:

    xfrm_output() -> xfrm_output_gso() -> skb_gso_segment()

where skb_gso_segment() relies on skb->protocol to function properly.

This patch sets skb->protocol to ETH_P_IP before dst_output() is called,
fixing a bug where GSO packets sent through a sit tunnel are dropped
when xfrm is involved.

Signed-off-by: Eli Cooper <elicooper@....com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Willy Tarreau <w@....eu>
---
 net/ipv4/ip_output.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c
index 57e7450..5f077ef 100644
--- a/net/ipv4/ip_output.c
+++ b/net/ipv4/ip_output.c
@@ -97,6 +97,9 @@ int __ip_local_out(struct sk_buff *skb)
 
 	iph->tot_len = htons(skb->len);
 	ip_send_check(iph);
+
+	skb->protocol = htons(ETH_P_IP);
+
 	return nf_hook(NFPROTO_IPV4, NF_INET_LOCAL_OUT, skb, NULL,
 		       skb_dst(skb)->dev, dst_output);
 }
-- 
2.8.0.rc2.1.gbe9624a