ipv6: make IPV6_RECVPKTINFO work for ipv4 datagrams

We currently don't report IPV6_RECVPKTINFO in cmsg access ancillary data
for IPv4 datagrams on IPv6 sockets.

This patch splits the ip6_datagram_recv_ctl into two functions, one
which handles both protocol families, AF_INET and AF_INET6, while the
ip6_datagram_recv_specific_ctl only handles IPv6 cmsg data.

ip6_datagram_recv_*_ctl never reported back any errors, so we can make
them return void. Also provide a helper for protocols which don't offer dual
personality to further use ip6_datagram_recv_ctl, which is exported to
modules.

I needed to shuffle the code for ping around a bit to make it easier to
implement dual personality for ping ipv6 sockets in future.

Reported-by: Gert Doering <gert@space.net>
Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 3 insertions, 0 deletions

diff --git a/include/linux/ipv6.h b/include/linux/ipv6.h
index 1084304fd75a..2faef339d8f2 100644
--- a/include/linux/ipv6.h
+++ b/include/linux/ipv6.h
@@ -284,6 +284,8 @@ static inline void inet_sk_copy_descendant(struct sock *sk_to,
 
 #define __ipv6_only_sock(sk)    (inet6_sk(sk)->ipv6only)
 #define ipv6_only_sock(sk)      ((sk)->sk_family == PF_INET6 && __ipv6_only_sock(sk))
+#define ipv6_sk_rxinfo(sk)      ((sk)->sk_family == PF_INET6 && \
+                                 inet6_sk(sk)->rxopt.bits.rxinfo)
 
 static inline const struct in6_addr *inet6_rcv_saddr(const struct sock *sk)
 {
@@ -300,6 +302,7 @@ static inline int inet_v6_ipv6only(const struct sock *sk)
 #else
 #define __ipv6_only_sock(sk)    0
 #define ipv6_only_sock(sk)      0
+#define ipv6_sk_rxinfo(sk)      0
 
 static inline struct ipv6_pinfo * inet6_sk(const struct sock *__sk)
 {