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>

6 files changed, 51 insertions, 20 deletions

diff --git a/net/ipv4/ip_sockglue.c b/net/ipv4/ip_sockglue.c
index 22f15eb1c260..580dd96666e0 100644
--- a/net/ipv4/ip_sockglue.c
+++ b/net/ipv4/ip_sockglue.c
@@ -56,7 +56,6 @@
 /*
  *      SOL_IP control messages.
  */
-#define PKTINFO_SKB_CB(__skb) ((struct in_pktinfo *)((__skb)->cb))
 
 static void ip_cmsg_recv_pktinfo(struct msghdr *msg, struct sk_buff *skb)
 {
@@ -1055,9 +1054,10 @@ e_inval:
 void ipv4_pktinfo_prepare(const struct sock *sk, struct sk_buff *skb)
 {
         struct in_pktinfo *pktinfo = PKTINFO_SKB_CB(skb);
+        bool prepare = (inet_sk(sk)->cmsg_flags & IP_CMSG_PKTINFO) ||
+                       ipv6_sk_rxinfo(sk);
 
-        if ((inet_sk(sk)->cmsg_flags & IP_CMSG_PKTINFO) &&
-            skb_rtable(skb)) {
+        if (prepare && skb_rtable(skb)) {
                 pktinfo->ipi_ifindex = inet_iif(skb);
                 pktinfo->ipi_spec_dst.s_addr = fib_compute_spec_dst(skb);
         } else {
diff --git a/net/ipv4/ping.c b/net/ipv4/ping.c
index e09e8839d622..4a9e4266a0c3 100644
--- a/net/ipv4/ping.c
+++ b/net/ipv4/ping.c
@@ -906,7 +906,12 @@ int ping_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
                 }
 
                 if (inet6_sk(sk)->rxopt.all)
-                        pingv6_ops.ip6_datagram_recv_ctl(sk, msg, skb);
+                        pingv6_ops.ip6_datagram_recv_common_ctl(sk, msg, skb);
+                if (skb->protocol == htons(ETH_P_IPV6) &&
+                    inet6_sk(sk)->rxopt.all)
+                        pingv6_ops.ip6_datagram_recv_specific_ctl(sk, msg, skb);
+                else if (skb->protocol == htons(ETH_P_IP) && isk->cmsg_flags)
+                        ip_cmsg_recv(msg, skb);
 #endif
         } else {
                 BUG();
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);
 
diff --git a/net/ipv6/ipv6_sockglue.c b/net/ipv6/ipv6_sockglue.c
index 7024a874e901..0a00f449de5e 100644
--- a/net/ipv6/ipv6_sockglue.c
+++ b/net/ipv6/ipv6_sockglue.c
@@ -1002,10 +1002,8 @@ static int do_ipv6_getsockopt(struct sock *sk, int level, int optname,
                 release_sock(sk);
 
                 if (skb) {
-                        int err = ip6_datagram_recv_ctl(sk, &msg, skb);
+                        ip6_datagram_recv_ctl(sk, &msg, skb);
                         kfree_skb(skb);
-                        if (err)
-                                return err;
                 } else {
                         if (np->rxopt.bits.rxinfo) {
                                 struct in6_pktinfo src_info;
diff --git a/net/ipv6/ping.c b/net/ipv6/ping.c
index cd71f3a540be..94a3d04c3200 100644
--- a/net/ipv6/ping.c
+++ b/net/ipv6/ping.c
@@ -62,10 +62,9 @@ static int dummy_ipv6_recv_error(struct sock *sk, struct msghdr *msg, int len,
 {
         return -EAFNOSUPPORT;
 }
-static int dummy_ip6_datagram_recv_ctl(struct sock *sk, struct msghdr *msg,
+static void dummy_ip6_datagram_recv_ctl(struct sock *sk, struct msghdr *msg,
                                        struct sk_buff *skb)
 {
-        return -EAFNOSUPPORT;
 }
 static int dummy_icmpv6_err_convert(u8 type, u8 code, int *err)
 {
@@ -254,7 +253,9 @@ int __init pingv6_init(void)
                 return ret;
 #endif
         pingv6_ops.ipv6_recv_error = ipv6_recv_error;
-        pingv6_ops.ip6_datagram_recv_ctl = ip6_datagram_recv_ctl;
+        pingv6_ops.ip6_datagram_recv_common_ctl = ip6_datagram_recv_common_ctl;
+        pingv6_ops.ip6_datagram_recv_specific_ctl =
+                ip6_datagram_recv_specific_ctl;
         pingv6_ops.icmpv6_err_convert = icmpv6_err_convert;
         pingv6_ops.ipv6_icmp_error = ipv6_icmp_error;
         pingv6_ops.ipv6_chk_addr = ipv6_chk_addr;
@@ -267,7 +268,8 @@ int __init pingv6_init(void)
 void pingv6_exit(void)
 {
         pingv6_ops.ipv6_recv_error = dummy_ipv6_recv_error;
-        pingv6_ops.ip6_datagram_recv_ctl = dummy_ip6_datagram_recv_ctl;
+        pingv6_ops.ip6_datagram_recv_common_ctl = dummy_ip6_datagram_recv_ctl;
+        pingv6_ops.ip6_datagram_recv_specific_ctl = dummy_ip6_datagram_recv_ctl;
         pingv6_ops.icmpv6_err_convert = dummy_icmpv6_err_convert;
         pingv6_ops.ipv6_icmp_error = dummy_ipv6_icmp_error;
         pingv6_ops.ipv6_chk_addr = dummy_ipv6_chk_addr;
diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
index 233c3ab6aee4..1e586d92260e 100644
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c
@@ -477,12 +477,16 @@ try_again:
                 }
                 *addr_len = sizeof(*sin6);
         }
+
+        if (np->rxopt.all)
+                ip6_datagram_recv_common_ctl(sk, msg, skb);
+
         if (is_udp4) {
                 if (inet->cmsg_flags)
                         ip_cmsg_recv(msg, skb);
         } else {
                 if (np->rxopt.all)
-                        ip6_datagram_recv_ctl(sk, msg, skb);
+                        ip6_datagram_recv_specific_ctl(sk, msg, skb);
         }
 
         err = copied;