IPv6: Complete IPV6_DONTFRAG support

Finally add support to detect a local IPV6_DONTFRAG event
and return the relevant data to the user if they've enabled
IPV6_RECVPATHMTU on the socket.  The next recvmsg() will
return no data, but have an IPV6_PATHMTU as ancillary data.

Signed-off-by: Brian Haley <brian.haley@hp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 16 insertions, 8 deletions

diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
index 54d43dd1f085..61e2bef56090 100644
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -1219,15 +1219,23 @@ int ip6_append_data(struct sock *sk, int getfrag(void *from, char *to,
          */
 
         inet->cork.length += length;
-        if (((length > mtu) && (sk->sk_protocol == IPPROTO_UDP)) &&
-            (rt->u.dst.dev->features & NETIF_F_UFO)) {
+        if (length > mtu) {
+                int proto = sk->sk_protocol;
+                if (dontfrag && (proto == IPPROTO_UDP || proto == IPPROTO_RAW)){
+                        ipv6_local_rxpmtu(sk, fl, mtu-exthdrlen);
+                        return -EMSGSIZE;
+                }
 
-                err = ip6_ufo_append_data(sk, getfrag, from, length, hh_len,
-                                          fragheaderlen, transhdrlen, mtu,
-                                          flags);
-                if (err)
-                        goto error;
-                return 0;
+                if (proto == IPPROTO_UDP &&
+                    (rt->u.dst.dev->features & NETIF_F_UFO)) {
+
+                        err = ip6_ufo_append_data(sk, getfrag, from, length,
+                                                  hh_len, fragheaderlen,
+                                                  transhdrlen, mtu, flags);
+                        if (err)
+                                goto error;
+                        return 0;
+                }
         }
 
         if ((skb = skb_peek_tail(&sk->sk_write_queue)) == NULL)