ipv6: honor IPV6_PKTINFO with v4 mapped addresses on sendmsg

In case we decide in udp6_sendmsg to send the packet down the ipv4
udp_sendmsg path because the destination is either of family AF_INET or
the destination is an ipv4 mapped ipv6 address, we don't honor the
maybe specified ipv4 mapped ipv6 address in IPV6_PKTINFO.

We simply can check for this option in ip_cmsg_send because no calls to
ipv6 module functions are needed to do so.

Reported-by: Gert Doering <gert@space.net>
Cc: Tore Anderson <tore@fud.no>
Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 2 insertions, 1 deletions

diff --git a/include/net/ip.h b/include/net/ip.h
index 23be0fd37937..4aa781b7f609 100644
--- a/include/net/ip.h
+++ b/include/net/ip.h
@@ -489,7 +489,8 @@ int ip_options_rcv_srr(struct sk_buff *skb);
 
 void ipv4_pktinfo_prepare(const struct sock *sk, struct sk_buff *skb);
 void ip_cmsg_recv(struct msghdr *msg, struct sk_buff *skb);
-int ip_cmsg_send(struct net *net, struct msghdr *msg, struct ipcm_cookie *ipc);
+int ip_cmsg_send(struct net *net, struct msghdr *msg,
+                 struct ipcm_cookie *ipc, bool allow_ipv6);
 int ip_setsockopt(struct sock *sk, int level, int optname, char __user *optval,
                   unsigned int optlen);
 int ip_getsockopt(struct sock *sk, int level, int optname, char __user *optval,