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>

3 files changed, 14 insertions, 4 deletions

diff --git a/include/net/ip.h b/include/net/ip.h
index 7876e3b96ce3..23be0fd37937 100644
--- a/include/net/ip.h
+++ b/include/net/ip.h
@@ -63,6 +63,7 @@ struct ipcm_cookie {
 };
 
 #define IPCB(skb) ((struct inet_skb_parm*)((skb)->cb))
+#define PKTINFO_SKB_CB(skb) ((struct in_pktinfo *)((skb)->cb))
 
 struct ip_ra_chain {
         struct ip_ra_chain __rcu *next;
diff --git a/include/net/ping.h b/include/net/ping.h
index 76013653e08c..026479b61a2d 100644
--- a/include/net/ping.h
+++ b/include/net/ping.h
@@ -33,8 +33,12 @@
 struct pingv6_ops {
         int (*ipv6_recv_error)(struct sock *sk, struct msghdr *msg, int len,
                                int *addr_len);
-        int (*ip6_datagram_recv_ctl)(struct sock *sk, struct msghdr *msg,
-                                     struct sk_buff *skb);
+        void (*ip6_datagram_recv_common_ctl)(struct sock *sk,
+                                             struct msghdr *msg,
+                                             struct sk_buff *skb);
+        void (*ip6_datagram_recv_specific_ctl)(struct sock *sk,
+                                               struct msghdr *msg,
+                                               struct sk_buff *skb);
         int (*icmpv6_err_convert)(u8 type, u8 code, int *err);
         void (*ipv6_icmp_error)(struct sock *sk, struct sk_buff *skb, int err,
                                 __be16 port, u32 info, u8 *payload);
diff --git a/include/net/transp_v6.h b/include/net/transp_v6.h
index 48660e50ae90..b927413dde86 100644
--- a/include/net/transp_v6.h
+++ b/include/net/transp_v6.h
@@ -32,8 +32,13 @@ void tcpv6_exit(void);
 
 int udpv6_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len);
 
-int ip6_datagram_recv_ctl(struct sock *sk, struct msghdr *msg,
-                          struct sk_buff *skb);
+/* this does all the common and the specific ctl work */
+void ip6_datagram_recv_ctl(struct sock *sk, struct msghdr *msg,
+                           struct sk_buff *skb);
+void ip6_datagram_recv_common_ctl(struct sock *sk, struct msghdr *msg,
+                                  struct sk_buff *skb);
+void ip6_datagram_recv_specific_ctl(struct sock *sk, struct msghdr *msg,
+                                    struct sk_buff *skb);
 
 int ip6_datagram_send_ctl(struct net *net, struct sock *sk, struct msghdr *msg,
                           struct flowi6 *fl6, struct ipv6_txoptions *opt,