sit: correct IP protocol used in ipip6_err

[ Upstream commit d5d8760b78d0cfafe292f965f599988138b06a70 ]

Since 32b8a8e59c9c ("sit: add IPv4 over IPv4 support")
ipip6_err() may be called for packets whose IP protocol is
IPPROTO_IPIP as well as those whose IP protocol is IPPROTO_IPV6.

In the case of IPPROTO_IPIP packets the correct protocol value is not
passed to ipv4_update_pmtu() or ipv4_redirect().

This patch resolves this problem by using the IP protocol of the packet
rather than a hard-coded value. This appears to be consistent
with the usage of the protocol of a packet by icmp_socket_deliver()
the caller of ipip6_err().

I was able to exercise the redirect case by using a setup where an ICMP
redirect was received for the destination of the encapsulated packet.
However, it appears that although incorrect the protocol field is not used
in this case and thus no problem manifests.  On inspection it does not
appear that a problem will manifest in the fragmentation needed/update pmtu
case either.

In short I believe this is a cosmetic fix. None the less, the use of
IPPROTO_IPV6 seems wrong and confusing.

Reviewed-by: Dinan Gunawardena <dinan.gunawardena@netronome.com>
Signed-off-by: Simon Horman <simon.horman@netronome.com>
Acked-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/net/ipv6/sit.c b/net/ipv6/sit.c
index b5bdd2aeb2f8498d0556a54cf8501a23b3dbdeed..75c2b56f3eebedc135fb8bf113680840699325bb 100644 (file)
--- a/net/ipv6/sit.c
+++ b/net/ipv6/sit.c
@@ -559,13 +559,13 @@ static int ipip6_err(struct sk_buff *skb, u32 info)
 
        if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED) {
                ipv4_update_pmtu(skb, dev_net(skb->dev), info,
-                                t->parms.link, 0, IPPROTO_IPV6, 0);
+                                t->parms.link, 0, iph->protocol, 0);
                err = 0;
                goto out;
        }
        if (type == ICMP_REDIRECT) {
                ipv4_redirect(skb, dev_net(skb->dev), t->parms.link, 0,
-                             IPPROTO_IPV6, 0);
+                             iph->protocol, 0);
                err = 0;
                goto out;
        }