ipv6: Fix ip6_xmit to send fragments if ipfragok is true

[ Upstream commit 77e2f14f71d68d05945f1d30ca55b5194d6ab1ce ]

SCTP used ip6_xmit() to send fragments after received ICMP packet too
big message. But while send packet used ip6_xmit, the skb->local_df is
not initialized. So when skb if enter ip6_fragment(), the following
code will discard the skb.

ip6_fragment(...)
{
    if (!skb->local_df) {
        ...
        return -EMSGSIZE;
    }
    ...
}

SCTP do the following step:
1. send packet ip6_xmit(skb, ipfragok=0)
2. received ICMP packet too big message
3. if PMTUD_ENABLE: ip6_xmit(skb, ipfragok=1)

This patch fixed the problem by set local_df if ipfragok is true.

Signed-off-by: Wei Yongjun <yjwei@cn.fujitsu.com>
Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
index 8b67ca07467d48e0bb3e62da1ae19d7a6d5b156e..fb1c192afd2447e60b901d300437d047e42e95a6 100644 (file)
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -229,6 +229,10 @@ int ip6_xmit(struct sock *sk, struct sk_buff *skb, struct flowi *fl,
        skb_reset_network_header(skb);
        hdr = ipv6_hdr(skb);
 
+       /* Allow local fragmentation. */
+       if (ipfragok)
+               skb->local_df = 1;
+
        /*
         *      Fill in the IPv6 header
         */