ipv6: Fix ipv6_getsockopt for IPV6_2292PKTOPTIONS

IPV6_2292PKTOPTIONS is broken for 32-bit applications running
in COMPAT mode on 64-bit kernels.

The same problem was fixed for IPv4 with the patch:
ipv4: Fix ip_getsockopt for IP_PKTOPTIONS,
commit dd23198eSigned-off-by: NSorin Dumitru <sdumitru@ixiacom.com>
Signed-off-by: NDaniel Baluta <dbaluta@ixiacom.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/ipv6/ipv6_sockglue.c

@@ -913,7 +913,7 @@ static int ipv6_getsockopt_sticky(struct sock *sk, struct ipv6_txoptions *opt,
 }
 
 static int do_ipv6_getsockopt(struct sock *sk, int level, int optname,
-		    char __user *optval, int __user *optlen)
+		    char __user *optval, int __user *optlen, unsigned flags)
 {
 	struct ipv6_pinfo *np = inet6_sk(sk);
 	int len;
@@ -962,7 +962,7 @@ static int do_ipv6_getsockopt(struct sock *sk, int level, int optname,
 
 		msg.msg_control = optval;
 		msg.msg_controllen = len;
-		msg.msg_flags = 0;
+		msg.msg_flags = flags;
 
 		lock_sock(sk);
 		skb = np->pktoptions;
@@ -1222,7 +1222,7 @@ int ipv6_getsockopt(struct sock *sk, int level, int optname,
 	if(level != SOL_IPV6)
 		return -ENOPROTOOPT;
 
-	err = do_ipv6_getsockopt(sk, level, optname, optval, optlen);
+	err = do_ipv6_getsockopt(sk, level, optname, optval, optlen, 0);
 #ifdef CONFIG_NETFILTER
 	/* we need to exclude all possible ENOPROTOOPTs except default case */
 	if (err == -ENOPROTOOPT && optname != IPV6_2292PKTOPTIONS) {
@@ -1264,7 +1264,8 @@ int compat_ipv6_getsockopt(struct sock *sk, int level, int optname,
 		return compat_mc_getsockopt(sk, level, optname, optval, optlen,
 			ipv6_getsockopt);
 
-	err = do_ipv6_getsockopt(sk, level, optname, optval, optlen);
+	err = do_ipv6_getsockopt(sk, level, optname, optval, optlen,
+				 MSG_CMSG_COMPAT);
 #ifdef CONFIG_NETFILTER
 	/* we need to exclude all possible ENOPROTOOPTs except default case */
 	if (err == -ENOPROTOOPT && optname != IPV6_2292PKTOPTIONS) {