handle the group_source_req options directly

Native ->setsockopt() handling of these options (MCAST_..._SOURCE_GROUP
and MCAST_{,UN}BLOCK_SOURCE) consists of copyin + call of a helper that
does the actual work.  The only change needed for ->compat_setsockopt()
is a slightly different copyin - the helpers can be reused as-is.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

net/ipv4/ip_sockglue.c

@@ -1322,8 +1322,27 @@ int compat_ip_setsockopt(struct sock *sk, int level, int optname,
 	case MCAST_LEAVE_SOURCE_GROUP:
 	case MCAST_BLOCK_SOURCE:
 	case MCAST_UNBLOCK_SOURCE:
-		return compat_mc_setsockopt(sk, level, optname, optval, optlen,
-			ip_setsockopt);
+	{
+		struct compat_group_source_req __user *gsr32 = (void __user *)optval;
+		struct group_source_req greqs;
+
+		if (optlen != sizeof(struct compat_group_source_req))
+			return -EINVAL;
+
+		if (get_user(greqs.gsr_interface, &gsr32->gsr_interface) ||
+		    copy_from_user(&greqs.gsr_group, &gsr32->gsr_group,
+				sizeof(greqs.gsr_group)) ||
+		    copy_from_user(&greqs.gsr_source, &gsr32->gsr_source,
+				sizeof(greqs.gsr_source)))
+			return -EFAULT;
+
+		rtnl_lock();
+		lock_sock(sk);
+		err = do_mcast_group_source(sk, optname, &greqs);
+		release_sock(sk);
+		rtnl_unlock();
+		return err;
+	}
 	case MCAST_MSFILTER:
 	{
 		const int size0 = offsetof(struct compat_group_filter, gf_slist);

net/ipv6/ipv6_sockglue.c

@@ -1015,8 +1015,27 @@ int compat_ipv6_setsockopt(struct sock *sk, int level, int optname,
 	case MCAST_LEAVE_SOURCE_GROUP:
 	case MCAST_BLOCK_SOURCE:
 	case MCAST_UNBLOCK_SOURCE:
-		return compat_mc_setsockopt(sk, level, optname, optval, optlen,
-			ipv6_setsockopt);
+	{
+		struct compat_group_source_req __user *gsr32 = (void __user *)optval;
+		struct group_source_req greqs;
+
+		if (optlen < sizeof(struct compat_group_source_req))
+			return -EINVAL;
+
+		if (get_user(greqs.gsr_interface, &gsr32->gsr_interface) ||
+		    copy_from_user(&greqs.gsr_group, &gsr32->gsr_group,
+				sizeof(greqs.gsr_group)) ||
+		    copy_from_user(&greqs.gsr_source, &gsr32->gsr_source,
+				sizeof(greqs.gsr_source)))
+			return -EFAULT;
+
+		rtnl_lock();
+		lock_sock(sk);
+		err = do_ipv6_mcast_group_source(sk, optname, &greqs);
+		release_sock(sk);
+		rtnl_unlock();
+		return err;
+	}
 	case MCAST_MSFILTER:
 	{
 		const int size0 = offsetof(struct compat_group_filter, gf_slist);