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authorUlrich Weber <uweber@astaro.com>2010-02-26 04:34:49 -0800
committerDavid S. Miller <davem@davemloft.net>2010-02-26 04:34:49 -0800
commit14f3ad6f4a12495b32b0dd743bc7179f36658208 (patch)
treebff2b347d1a1755955ba1b37c561b1bff2f6d861 /net/ipv6
parentfbf219f1c89b15e90ec2db5a3e9636376dc623db (diff)
ipv6: Use 1280 as min MTU for ipv6 forwarding
Clients will set their MTU to 1280 if they receive a ICMPV6_PKT_TOOBIG message with an MTU less than 1280. To allow encapsulating of packets over a 1280 link we should always accept packets with a size of 1280 for forwarding even if the path has a lower MTU and fragment the encapsulated packets afterwards. In case a forwarded packet is not going to be encapsulated a ICMPV6_PKT_TOOBIG msg will still be send by ip6_fragment() with the correct MTU. Signed-off-by: Ulrich Weber <uweber@astaro.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv6')
-rw-r--r--net/ipv6/ip6_output.c12
1 files changed, 8 insertions, 4 deletions
diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
index 1a5fe9ad194..dabf108ad81 100644
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -402,6 +402,7 @@ int ip6_forward(struct sk_buff *skb)
struct ipv6hdr *hdr = ipv6_hdr(skb);
struct inet6_skb_parm *opt = IP6CB(skb);
struct net *net = dev_net(dst->dev);
+ u32 mtu;
if (net->ipv6.devconf_all->forwarding == 0)
goto error;
@@ -508,10 +509,14 @@ int ip6_forward(struct sk_buff *skb)
}
}
- if (skb->len > dst_mtu(dst)) {
+ mtu = dst_mtu(dst);
+ if (mtu < IPV6_MIN_MTU)
+ mtu = IPV6_MIN_MTU;
+
+ if (skb->len > mtu) {
/* Again, force OUTPUT device used as source address */
skb->dev = dst->dev;
- icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, dst_mtu(dst));
+ icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu);
IP6_INC_STATS_BH(net,
ip6_dst_idev(dst), IPSTATS_MIB_INTOOBIGERRORS);
IP6_INC_STATS_BH(net,
@@ -621,8 +626,7 @@ static int ip6_fragment(struct sk_buff *skb, int (*output)(struct sk_buff *))
mtu = ip6_skb_dst_mtu(skb);
/* We must not fragment if the socket is set to force MTU discovery
- * or if the skb it not generated by a local socket. (This last
- * check should be redundant, but it's free.)
+ * or if the skb it not generated by a local socket.
*/
if (!skb->local_df) {
skb->dev = skb_dst(skb)->dev;