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, 30 insertions, 8 deletions

diff --git a/net/ipv6/datagram.c b/net/ipv6/datagram.c
index bce73cbd203a..cd8699bd2e6b 100644
--- a/net/ipv6/datagram.c
+++ b/net/ipv6/datagram.c
@@ -377,10 +377,12 @@ int ipv6_recv_error(struct sock *sk, struct msghdr *msg, int len, int *addr_len)
 		sin->sin6_family = AF_INET6;
 		sin->sin6_flowinfo = 0;
 		sin->sin6_port = 0;
+		if (np->rxopt.all)
+			ip6_datagram_recv_common_ctl(sk, msg, skb);
 		if (skb->protocol == htons(ETH_P_IPV6)) {
 			sin->sin6_addr = ipv6_hdr(skb)->saddr;
 			if (np->rxopt.all)
-				ip6_datagram_recv_ctl(sk, msg, skb);
+				ip6_datagram_recv_specific_ctl(sk, msg, skb);
 			sin->sin6_scope_id =
 				ipv6_iface_scope_id(&sin->sin6_addr,
 						    IP6CB(skb)->iif);
@@ -471,20 +473,34 @@ out:
 }
 
 
-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)
 {
 	struct ipv6_pinfo *np = inet6_sk(sk);
-	struct inet6_skb_parm *opt = IP6CB(skb);
-	unsigned char *nh = skb_network_header(skb);
+	bool is_ipv6 = skb->protocol == htons(ETH_P_IPV6);
 
 	if (np->rxopt.bits.rxinfo) {
 		struct in6_pktinfo src_info;
 
-		src_info.ipi6_ifindex = opt->iif;
-		src_info.ipi6_addr = ipv6_hdr(skb)->daddr;
+		if (is_ipv6) {
+			src_info.ipi6_ifindex = IP6CB(skb)->iif;
+			src_info.ipi6_addr = ipv6_hdr(skb)->daddr;
+		} else {
+			src_info.ipi6_ifindex =
+				PKTINFO_SKB_CB(skb)->ipi_ifindex;
+			ipv6_addr_set_v4mapped(ip_hdr(skb)->daddr,
+					       &src_info.ipi6_addr);
+		}
 		put_cmsg(msg, SOL_IPV6, IPV6_PKTINFO, sizeof(src_info), &src_info);
 	}
+}
+
+void ip6_datagram_recv_specific_ctl(struct sock *sk, struct msghdr *msg,
+				    struct sk_buff *skb)
+{
+	struct ipv6_pinfo *np = inet6_sk(sk);
+	struct inet6_skb_parm *opt = IP6CB(skb);
+	unsigned char *nh = skb_network_header(skb);
 
 	if (np->rxopt.bits.rxhlim) {
 		int hlim = ipv6_hdr(skb)->hop_limit;
@@ -602,7 +618,13 @@ int ip6_datagram_recv_ctl(struct sock *sk, struct msghdr *msg,
 			put_cmsg(msg, SOL_IPV6, IPV6_ORIGDSTADDR, sizeof(sin6), &sin6);
 		}
 	}
-	return 0;
+}
+
+void ip6_datagram_recv_ctl(struct sock *sk, struct msghdr *msg,
+			  struct sk_buff *skb)
+{
+	ip6_datagram_recv_common_ctl(sk, msg, skb);
+	ip6_datagram_recv_specific_ctl(sk, msg, skb);
 }
 EXPORT_SYMBOL_GPL(ip6_datagram_recv_ctl);