ipv4: Enforce max MTU metric at route insertion time.

Rather than at every struct rtable creation.

Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 3 insertions, 6 deletions

diff --git a/net/ipv4/fib_semantics.c b/net/ipv4/fib_semantics.c
index ae301c897a19..d71bfbdc0bf4 100644
--- a/net/ipv4/fib_semantics.c
+++ b/net/ipv4/fib_semantics.c
@@ -794,6 +794,8 @@ struct fib_info *fib_create_info(struct fib_config *cfg)
                                 val = nla_get_u32(nla);
                                 if (type == RTAX_ADVMSS && val > 65535 - 40)
                                         val = 65535 - 40;
+                                if (type == RTAX_MTU && val > 65535 - 15)
+                                        val = 65535 - 15;
                                 fi->fib_metrics[type - 1] = val;
                         }
                 }
diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index 677d65253e4c..1678b575165b 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -1763,21 +1763,16 @@ static void rt_set_nexthop(struct rtable *rt, const struct flowi4 *fl4,
                            const struct fib_result *res,
                            struct fib_info *fi, u16 type, u32 itag)
 {
-        struct dst_entry *dst = &rt->dst;
-
         if (fi) {
                 if (FIB_RES_GW(*res) &&
                     FIB_RES_NH(*res).nh_scope == RT_SCOPE_LINK)
                         rt->rt_gateway = FIB_RES_GW(*res);
                 rt_init_metrics(rt, fl4, fi);
 #ifdef CONFIG_IP_ROUTE_CLASSID
-                dst->tclassid = FIB_RES_NH(*res).nh_tclassid;
+                rt->dst.tclassid = FIB_RES_NH(*res).nh_tclassid;
 #endif
         }
 
-        if (dst_mtu(dst) > IP_MAX_MTU)
-                dst_metric_set(dst, RTAX_MTU, IP_MAX_MTU);
-
 #ifdef CONFIG_IP_ROUTE_CLASSID
 #ifdef CONFIG_IP_MULTIPLE_TABLES
         set_class_tag(rt, fib_rules_tclass(res));