netdev - [PATCH] ipv4: Cap ADVMSS metric in the FIB rather than the routing cache.

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Message-Id: <20120617.195356.1115146370520234751.davem@davemloft.net>
Date:	Sun, 17 Jun 2012 19:53:56 -0700 (PDT)
From:	David Miller <davem@...emloft.net>
To:	netdev@...r.kernel.org
Subject: [PATCH] ipv4: Cap ADVMSS metric in the FIB rather than the routing
 cache.


It makes no sense to execute this limit test every time we create a
routing cache entry.

We can't simply error out on these things since we've silently
accepted and truncated them forever.

Signed-off-by: David S. Miller <davem@...emloft.net>
---
 net/ipv4/fib_semantics.c |    7 ++++++-
 net/ipv4/route.c         |    2 --
 2 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/net/ipv4/fib_semantics.c b/net/ipv4/fib_semantics.c
index e5b7182..415f823 100644
--- a/net/ipv4/fib_semantics.c
+++ b/net/ipv4/fib_semantics.c
@@ -779,9 +779,14 @@ struct fib_info *fib_create_info(struct fib_config *cfg)
 			int type = nla_type(nla);
 
 			if (type) {
+				u32 val;
+
 				if (type > RTAX_MAX)
 					goto err_inval;
-				fi->fib_metrics[type - 1] = nla_get_u32(nla);
+				val = nla_get_u32(nla);
+				if (type == RTAX_ADVMSS && val > 65535 - 40)
+					val = 65535 - 40;
+				fi->fib_metrics[type - 1] = val;
 			}
 		}
 	}
diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index 41df529..a91f6d3 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -1951,8 +1951,6 @@ static void rt_set_nexthop(struct rtable *rt, const struct flowi4 *fl4,
 
 	if (dst_mtu(dst) > IP_MAX_MTU)
 		dst_metric_set(dst, RTAX_MTU, IP_MAX_MTU);
-	if (dst_metric_raw(dst, RTAX_ADVMSS) > 65535 - 40)
-		dst_metric_set(dst, RTAX_ADVMSS, 65535 - 40);
 
 #ifdef CONFIG_IP_ROUTE_CLASSID
 #ifdef CONFIG_IP_MULTIPLE_TABLES
-- 
1.7.10

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