tipc: add ioctl to fetch link names

We add a new ioctl for AF_TIPC that can be used to fetch the
logical name for a link to a remote node on a given bearer. This
should be used in combination with link state subscriptions.
The logical name size limit definitions are moved to tipc.h, as
they are now also needed by the new ioctl.

Signed-off-by: Erik Hugne <erik.hugne@ericsson.com>
Reviewed-by: Ying Xue <ying.xue@windriver.com>
Reviewed-by: Jon Maloy <jon.maloy@ericsson.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

3 files changed, 54 insertions, 3 deletions

diff --git a/net/tipc/node.c b/net/tipc/node.c
index 3b86a74..1f938f3 100644
--- a/net/tipc/node.c
+++ b/net/tipc/node.c
@@ -438,3 +438,30 @@ struct sk_buff *tipc_node_get_links(const void *req_tlv_area, int req_tlv_space)
 	rcu_read_unlock();
 	return buf;
 }
+
+/**
+ * tipc_node_get_linkname - get the name of a link
+ *
+ * @bearer_id: id of the bearer
+ * @node: peer node address
+ * @linkname: link name output buffer
+ *
+ * Returns 0 on success
+ */
+int tipc_node_get_linkname(u32 bearer_id, u32 addr, char *linkname, size_t len)
+{
+	struct tipc_link *link;
+	struct tipc_node *node = tipc_node_find(addr);
+
+	if ((bearer_id > MAX_BEARERS) || !node)
+		return -EINVAL;
+	tipc_node_lock(node);
+	link = node->links[bearer_id];
+	if (link) {
+		strncpy(linkname, link->name, len);
+		tipc_node_unlock(node);
+		return 0;
+	}
+	tipc_node_unlock(node);
+	return -EINVAL;
+}
diff --git a/net/tipc/node.h b/net/tipc/node.h
index 7cbb8ce..411b191 100644
--- a/net/tipc/node.h
+++ b/net/tipc/node.h
@@ -118,6 +118,7 @@ int tipc_node_active_links(struct tipc_node *n_ptr);
 int tipc_node_is_up(struct tipc_node *n_ptr);
 struct sk_buff *tipc_node_get_links(const void *req_tlv_area, int req_tlv_space);
 struct sk_buff *tipc_node_get_nodes(const void *req_tlv_area, int req_tlv_space);
+int tipc_node_get_linkname(u32 bearer_id, u32 node, char *linkname, size_t len);
 
 static inline void tipc_node_lock(struct tipc_node *n_ptr)
 {
diff --git a/net/tipc/socket.c b/net/tipc/socket.c
index 3c02569..3f9912f 100644
--- a/net/tipc/socket.c
+++ b/net/tipc/socket.c
@@ -36,6 +36,7 @@
 
 #include "core.h"
 #include "port.h"
+#include "node.h"
 
 #include <linux/export.h>
 
@@ -1905,6 +1906,28 @@ static int tipc_getsockopt(struct socket *sock, int lvl, int opt,
 	return put_user(sizeof(value), ol);
 }
 
+int tipc_ioctl(struct socket *sk, unsigned int cmd, unsigned long arg)
+{
+	struct tipc_sioc_ln_req lnr;
+	void __user *argp = (void __user *)arg;
+
+	switch (cmd) {
+	case SIOCGETLINKNAME:
+		if (copy_from_user(&lnr, argp, sizeof(lnr)))
+			return -EFAULT;
+		if (!tipc_node_get_linkname(lnr.bearer_id, lnr.peer,
+					    lnr.linkname, TIPC_MAX_LINK_NAME)) {
+			if (copy_to_user(argp, &lnr, sizeof(lnr)))
+				return -EFAULT;
+			return 0;
+		}
+		return -EADDRNOTAVAIL;
+		break;
+	default:
+		return -ENOIOCTLCMD;
+	}
+}
+
 /* Protocol switches for the various types of TIPC sockets */
 
 static const struct proto_ops msg_ops = {
@@ -1917,7 +1940,7 @@ static const struct proto_ops msg_ops = {
 	.accept		= sock_no_accept,
 	.getname	= tipc_getname,
 	.poll		= tipc_poll,
-	.ioctl		= sock_no_ioctl,
+	.ioctl		= tipc_ioctl,
 	.listen		= sock_no_listen,
 	.shutdown	= tipc_shutdown,
 	.setsockopt	= tipc_setsockopt,
@@ -1938,7 +1961,7 @@ static const struct proto_ops packet_ops = {
 	.accept		= tipc_accept,
 	.getname	= tipc_getname,
 	.poll		= tipc_poll,
-	.ioctl		= sock_no_ioctl,
+	.ioctl		= tipc_ioctl,
 	.listen		= tipc_listen,
 	.shutdown	= tipc_shutdown,
 	.setsockopt	= tipc_setsockopt,
@@ -1959,7 +1982,7 @@ static const struct proto_ops stream_ops = {
 	.accept		= tipc_accept,
 	.getname	= tipc_getname,
 	.poll		= tipc_poll,
-	.ioctl		= sock_no_ioctl,
+	.ioctl		= tipc_ioctl,
 	.listen		= tipc_listen,
 	.shutdown	= tipc_shutdown,
 	.setsockopt	= tipc_setsockopt,