network: remove netpipe

src/lxc/network.c

@@ -45,6 +45,7 @@
 #include <sys/stat.h>
 #include <sys/types.h>
 
+#include "af_unix.h"
 #include "conf.h"
 #include "config.h"
 #include "log.h"
@@ -2963,3 +2964,65 @@ int lxc_setup_network_in_child_namespaces(const struct lxc_conf *conf,
 
 	return 0;
 }
+
+int lxc_network_send_veth_names_to_child(struct lxc_handler *handler)
+{
+	struct lxc_list *iterator;
+	struct lxc_list *network = &handler->conf->network;
+	int data_sock = handler->data_sock[0];
+
+	if (handler->root)
+		return 0;
+
+	lxc_list_for_each(iterator, network) {
+		int ret;
+		struct lxc_netdev *netdev = iterator->elem;
+
+		if (netdev->type != LXC_NET_VETH)
+			continue;
+
+		ret = lxc_abstract_unix_send_credential(data_sock, netdev->name,
+							IFNAMSIZ);
+		if (ret < 0) {
+			close(handler->data_sock[0]);
+			close(handler->data_sock[1]);
+			return -1;
+		} else {
+			TRACE("Sent network device name \"%s\" to child",
+			      netdev->name);
+		}
+	}
+
+	return 0;
+}
+
+int lxc_network_recv_veth_names_from_parent(struct lxc_handler *handler)
+{
+	struct lxc_list *iterator;
+	struct lxc_list *network = &handler->conf->network;
+	int data_sock = handler->data_sock[1];
+
+	if (handler->root)
+		return 0;
+
+	lxc_list_for_each(iterator, network) {
+		int ret;
+		struct lxc_netdev *netdev = iterator->elem;
+
+		if (netdev->type != LXC_NET_VETH)
+			continue;
+
+		ret = lxc_abstract_unix_rcv_credential(data_sock, netdev->name,
+						       IFNAMSIZ);
+		if (ret < 0) {
+			close(handler->data_sock[0]);
+			close(handler->data_sock[1]);
+			return -1;
+		} else {
+			TRACE("Received network device name \"%s\" from parent",
+			      netdev->name);
+		}
+	}
+
+	return 0;
+}

src/lxc/network.h

@@ -305,5 +305,7 @@ extern int lxc_requests_empty_network(struct lxc_handler *handler);
 extern int lxc_restore_phys_nics_to_netns(struct lxc_handler *handler);
 extern int lxc_setup_network_in_child_namespaces(const struct lxc_conf *conf,
 						 struct lxc_list *network);
+extern int lxc_network_send_veth_names_to_child(struct lxc_handler *handler);
+extern int lxc_network_recv_veth_names_from_parent(struct lxc_handler *handler);
 
 #endif /* __LXC_NETWORK_H */

src/lxc/start.c

@@ -854,48 +854,6 @@ static int must_drop_cap_sys_boot(struct lxc_conf *conf)
 	return 0;
 }
 
-/* netpipe is used in the unprivileged case to transfer the ifindexes from
- * parent to child
- */
-static int netpipe = -1;
-
-static inline int count_veths(struct lxc_list *network)
-{
-	struct lxc_list *iterator;
-	struct lxc_netdev *netdev;
-	int count = 0;
-
-	lxc_list_for_each(iterator, network) {
-		netdev = iterator->elem;
-		if (netdev->type != LXC_NET_VETH)
-			continue;
-		count++;
-	}
-	return count;
-}
-
-static int read_unpriv_netifindex(struct lxc_list *network)
-{
-	struct lxc_list *iterator;
-	struct lxc_netdev *netdev;
-
-	if (netpipe == -1)
-		return 0;
-
-	lxc_list_for_each(iterator, network) {
-		netdev = iterator->elem;
-		if (netdev->type != LXC_NET_VETH)
-			continue;
-
-		if (read(netpipe, netdev->name, IFNAMSIZ) != IFNAMSIZ) {
-			close(netpipe);
-			return -1;
-		}
-	}
-	close(netpipe);
-	return 0;
-}
-
 static int do_start(void *data)
 {
 	struct lxc_list *iterator;
@@ -948,8 +906,10 @@ static int do_start(void *data)
 	if (lxc_sync_barrier_parent(handler, LXC_SYNC_CONFIGURE))
 		return -1;
 
-	if (read_unpriv_netifindex(&handler->conf->network) < 0)
+	if (lxc_network_recv_veth_names_from_parent(handler) < 0) {
+		ERROR("Failed to receive veth names from parent");
 		goto out_warn_father;
+	}
 
 	/* If we are in a new user namespace, become root there to have
 	 * privilege over our namespace.
@@ -1278,15 +1238,14 @@ void resolve_clone_flags(struct lxc_handler *handler)
  */
 static int lxc_spawn(struct lxc_handler *handler)
 {
-	int i, flags, nveths, ret;
+	int i, flags, ret;
 	const char *name = handler->name;
 	bool wants_to_map_ids;
-	int netpipepair[2], saved_ns_fd[LXC_NS_MAX];
+	int saved_ns_fd[LXC_NS_MAX];
 	struct lxc_list *id_map;
 	int failed_before_rename = 0, preserve_mask = 0;
 	bool cgroups_connected = false;
 
-	netpipe = -1;
 	id_map = &handler->conf->id_map;
 	wants_to_map_ids = !lxc_list_empty(id_map);
 
@@ -1359,15 +1318,6 @@ static int lxc_spawn(struct lxc_handler *handler)
 	if (attach_ns(handler->conf->inherit_ns_fd) < 0)
 		goto out_delete_net;
 
-	if (!handler->root && (nveths = count_veths(&handler->conf->network))) {
-		if (pipe(netpipepair) < 0) {
-			SYSERROR("Failed to create pipe.");
-			goto out_delete_net;
-		}
-		/* Store netpipe in the global var for do_start's use. */
-		netpipe = netpipepair[0];
-	}
-
 	/* Create a process in a new set of namespaces. */
 	flags = handler->clone_flags;
 	if (handler->clone_flags & CLONE_NEWUSER) {
@@ -1459,22 +1409,10 @@ static int lxc_spawn(struct lxc_handler *handler)
 		}
 	}
 
-	if (netpipe != -1) {
-		struct lxc_list *iterator;
-		struct lxc_netdev *netdev;
-
-		close(netpipe);
-		lxc_list_for_each(iterator, &handler->conf->network) {
-			netdev = iterator->elem;
-			if (netdev->type != LXC_NET_VETH)
-				continue;
-			if (write(netpipepair[1], netdev->name, IFNAMSIZ) != IFNAMSIZ) {
-				ERROR("Error writing veth name to container.");
+	if (lxc_network_send_veth_names_to_child(handler) < 0) {
+		ERROR("Failed to send veth names to child");
 		goto out_delete_net;
 	}
-		}
-		close(netpipepair[1]);
-	}
 
 	/* Tell the child to continue its initialization. We'll get
 	 * LXC_SYNC_CGROUP when it is ready for us to setup cgroups.