netdev - [PATCH net-next 4/6] mpls: Correct the ttl decrement.

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Message-ID: <87a8zo4fc4.fsf@x220.int.ebiederm.org>
Date:	Sat, 07 Mar 2015 16:23:23 -0600
From:	ebiederm@...ssion.com (Eric W. Biederman)
To:	David Miller <davem@...emloft.net>
Cc:	<netdev@...r.kernel.org>
Subject: [PATCH net-next 4/6] mpls: Correct the ttl decrement.

According to RFC3032 section 2.4.2  packets with an outgoing
ttl of 0 MUST NOT be forwarded.  According to section 2.4.1
an outgoing TTL of 0 comes from an incomming TTL <= 1.

Therefore any packets that is received with a ttl <= 1 should
not have it's ttl decremented and forwarded.

Signed-off-by: "Eric W. Biederman" <ebiederm@...ssion.com>
---
 net/mpls/af_mpls.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/mpls/af_mpls.c b/net/mpls/af_mpls.c
index 5c99e3fc1b72..e120074157de 100644
--- a/net/mpls/af_mpls.c
+++ b/net/mpls/af_mpls.c
@@ -162,7 +162,7 @@ static int mpls_forward(struct sk_buff *skb, struct net_device *dev,
 	skb_forward_csum(skb);

 	/* Verify ttl is valid */
-	if (dec.ttl <= 2)
+	if (dec.ttl <= 1)
 		goto drop;
 	dec.ttl -= 1;

-- 
2.2.1

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