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-rw-r--r--include/uapi/linux/netlink.h17
-rw-r--r--net/netlink/af_netlink.c22
2 files changed, 31 insertions, 8 deletions
diff --git a/include/uapi/linux/netlink.h b/include/uapi/linux/netlink.h
index 3e34b7d702f8..cf6a65cccbdf 100644
--- a/include/uapi/linux/netlink.h
+++ b/include/uapi/linux/netlink.h
@@ -101,14 +101,15 @@ struct nlmsgerr {
 	struct nlmsghdr msg;
 };
 
-#define NETLINK_ADD_MEMBERSHIP	1
-#define NETLINK_DROP_MEMBERSHIP	2
-#define NETLINK_PKTINFO		3
-#define NETLINK_BROADCAST_ERROR	4
-#define NETLINK_NO_ENOBUFS	5
-#define NETLINK_RX_RING		6
-#define NETLINK_TX_RING		7
-#define NETLINK_LISTEN_ALL_NSID	8
+#define NETLINK_ADD_MEMBERSHIP		1
+#define NETLINK_DROP_MEMBERSHIP		2
+#define NETLINK_PKTINFO			3
+#define NETLINK_BROADCAST_ERROR		4
+#define NETLINK_NO_ENOBUFS		5
+#define NETLINK_RX_RING			6
+#define NETLINK_TX_RING			7
+#define NETLINK_LISTEN_ALL_NSID		8
+#define NETLINK_LIST_MEMBERSHIPS	9
 
 struct nl_pktinfo {
 	__u32	group;
diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
index 69d67c300b80..dea925388a5b 100644
--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -2290,6 +2290,28 @@ static int netlink_getsockopt(struct socket *sock, int level, int optname,
 			return -EFAULT;
 		err = 0;
 		break;
+	case NETLINK_LIST_MEMBERSHIPS: {
+		int pos, idx, shift;
+
+		err = 0;
+		netlink_table_grab();
+		for (pos = 0; pos * 8 < nlk->ngroups; pos += sizeof(u32)) {
+			if (len - pos < sizeof(u32))
+				break;
+
+			idx = pos / sizeof(unsigned long);
+			shift = (pos % sizeof(unsigned long)) * 8;
+			if (put_user((u32)(nlk->groups[idx] >> shift),
+				     (u32 __user *)(optval + pos))) {
+				err = -EFAULT;
+				break;
+			}
+		}
+		if (put_user(ALIGN(nlk->ngroups / 8, sizeof(u32)), optlen))
+			err = -EFAULT;
+		netlink_table_ungrab();
+		break;
+	}
 	default:
 		err = -ENOPROTOOPT;
 	}