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/include/uapi/linux/tipc.h b/include/uapi/linux/tipc.h
index bf6d286..6b2fd4d 100644
--- a/include/uapi/linux/tipc.h
+++ b/include/uapi/linux/tipc.h
@@ -209,16 +209,16 @@
  * The string formatting for each name element is:
  * media: media
  * interface: media:interface name
- * link: Z.C.N:interface-Z.C.N:interface
- *
+ * link: node:interface-node:interface
  */
-
+#define TIPC_NODEID_LEN         16
 #define TIPC_MAX_MEDIA_NAME	16
 #define TIPC_MAX_IF_NAME	16
 #define TIPC_MAX_BEARER_NAME	32
 #define TIPC_MAX_LINK_NAME	68
 
-#define SIOCGETLINKNAME		SIOCPROTOPRIVATE
+#define SIOCGETLINKNAME        SIOCPROTOPRIVATE
+#define SIOCGETNODEID          (SIOCPROTOPRIVATE + 1)
 
 struct tipc_sioc_ln_req {
 	__u32 peer;
@@ -226,6 +226,10 @@
 	char linkname[TIPC_MAX_LINK_NAME];
 };
 
+struct tipc_sioc_nodeid_req {
+	__u32 peer;
+	char node_id[TIPC_NODEID_LEN];
+};
 
 /* The macros and functions below are deprecated:
  */
diff --git a/net/tipc/node.c b/net/tipc/node.c
index e9c52e14..81e6dd0 100644
--- a/net/tipc/node.c
+++ b/net/tipc/node.c
@@ -195,6 +195,27 @@
 	return mtu;
 }
 
+bool tipc_node_get_id(struct net *net, u32 addr, u8 *id)
+{
+	u8 *own_id = tipc_own_id(net);
+	struct tipc_node *n;
+
+	if (!own_id)
+		return true;
+
+	if (addr == tipc_own_addr(net)) {
+		memcpy(id, own_id, TIPC_NODEID_LEN);
+		return true;
+	}
+	n = tipc_node_find(net, addr);
+	if (!n)
+		return false;
+
+	memcpy(id, &n->peer_id, TIPC_NODEID_LEN);
+	tipc_node_put(n);
+	return true;
+}
+
 u16 tipc_node_get_capabilities(struct net *net, u32 addr)
 {
 	struct tipc_node *n;
diff --git a/net/tipc/node.h b/net/tipc/node.h
index bb271a3..846c8f2 100644
--- a/net/tipc/node.h
+++ b/net/tipc/node.h
@@ -60,6 +60,7 @@
 #define INVALID_BEARER_ID -1
 
 void tipc_node_stop(struct net *net);
+bool tipc_node_get_id(struct net *net, u32 addr, u8 *id);
 u32 tipc_node_try_addr(struct net *net, u8 *id, u32 addr);
 void tipc_node_check_dest(struct net *net, u32 onode, u8 *peer_id128,
 			  struct tipc_bearer *bearer,
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_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 @@
 	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 @@
 			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;
 	}