[IPV6]: Do not ignore IPV6_MTU socket option.

Based on patch by Hoerdt Mickael <hoerdt@clarinet.u-strasbg.fr>.

Signed-off-by: YOSHIFUJI Hideaki <yosufuji@linux-ipv6.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 13 insertions, 2 deletions

diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
index efa3e72cfcfa..f999edd846a9 100644
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -494,6 +494,7 @@ static int ip6_fragment(struct sk_buff *skb, int (*output)(struct sk_buff *))
         struct net_device *dev;
         struct sk_buff *frag;
         struct rt6_info *rt = (struct rt6_info*)skb->dst;
+        struct ipv6_pinfo *np = skb->sk ? inet6_sk(skb->sk) : NULL;
         struct ipv6hdr *tmp_hdr;
         struct frag_hdr *fh;
         unsigned int mtu, hlen, left, len;
@@ -505,7 +506,12 @@ static int ip6_fragment(struct sk_buff *skb, int (*output)(struct sk_buff *))
         hlen = ip6_find_1stfragopt(skb, &prevhdr);
         nexthdr = *prevhdr;
 
-        mtu = dst_mtu(&rt->u.dst) - hlen - sizeof(struct frag_hdr);
+        mtu = dst_mtu(&rt->u.dst);
+        if (np && np->frag_size < mtu) {
+                if (np->frag_size)
+                        mtu = np->frag_size;
+        }
+        mtu -= hlen + sizeof(struct frag_hdr);
 
         if (skb_shinfo(skb)->frag_list) {
                 int first_len = skb_pagelen(skb);
@@ -882,7 +888,12 @@ int ip6_append_data(struct sock *sk, int getfrag(void *from, char *to,
                 inet->cork.fl = *fl;
                 np->cork.hop_limit = hlimit;
                 np->cork.tclass = tclass;
-                inet->cork.fragsize = mtu = dst_mtu(rt->u.dst.path);
+                mtu = dst_mtu(rt->u.dst.path);
+                if (np && np->frag_size < mtu) {
+                        if (np->frag_size)
+                                mtu = np->frag_size;
+                }
+                inet->cork.fragsize = mtu;
                 if (dst_allfrag(rt->u.dst.path))
                         inet->cork.flags |= IPCORK_ALLFRAG;
                 inet->cork.length = 0;