tipc: introduce ioctl for fetching node identity

After the introduction of a 128-bit node identity it may be difficult
for a user to correlate between this identity and the generated node
hash address.

We now try to make this easier by introducing a new ioctl() call for
fetching a node identity by using the hash value as key. This will
be particularly useful when we extend some of the commands in the
'tipc' tool, but we also expect regular user applications to need
this feature.

Acked-by: Ying Xue <ying.xue@windriver.com>
Signed-off-by: Jon Maloy <jon.maloy@ericsson.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/tipc/socket.c b/net/tipc/socket.c
index 252a52ae..c499200 100644
--- a/net/tipc/socket.c
+++ b/net/tipc/socket.c
@@ -2973,7 +2973,8 @@ static int tipc_getsockopt(struct socket *sock, int lvl, int opt,
 
 static int tipc_ioctl(struct socket *sock, unsigned int cmd, unsigned long arg)
 {
-	struct sock *sk = sock->sk;
+	struct net *net = sock_net(sock->sk);
+	struct tipc_sioc_nodeid_req nr = {0};
 	struct tipc_sioc_ln_req lnr;
 	void __user *argp = (void __user *)arg;
 
@@ -2981,7 +2982,7 @@ static int tipc_ioctl(struct socket *sock, unsigned int cmd, unsigned long arg)
 	case SIOCGETLINKNAME:
 		if (copy_from_user(&lnr, argp, sizeof(lnr)))
 			return -EFAULT;
-		if (!tipc_node_get_linkname(sock_net(sk),
+		if (!tipc_node_get_linkname(net,
 					    lnr.bearer_id & 0xffff, lnr.peer,
 					    lnr.linkname, TIPC_MAX_LINK_NAME)) {
 			if (copy_to_user(argp, &lnr, sizeof(lnr)))
@@ -2989,6 +2990,14 @@ static int tipc_ioctl(struct socket *sock, unsigned int cmd, unsigned long arg)
 			return 0;
 		}
 		return -EADDRNOTAVAIL;
+	case SIOCGETNODEID:
+		if (copy_from_user(&nr, argp, sizeof(nr)))
+			return -EFAULT;
+		if (!tipc_node_get_id(net, nr.peer, nr.node_id))
+			return -EADDRNOTAVAIL;
+		if (copy_to_user(argp, &nr, sizeof(nr)))
+			return -EFAULT;
+		return 0;
 	default:
 		return -ENOIOCTLCMD;
 	}