network: rework network device creation

This makes all the codepaths easier to follow and also moves and renames
devices in one single step.

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

src/lxc/network.c

@@ -47,6 +47,7 @@
 lxc_log_define(network, lxc);
 
 typedef int (*instantiate_cb)(struct lxc_handler *, struct lxc_netdev *);
+typedef int (*instantiate_ns_cb)(struct lxc_netdev *);
 static const char loop_device[] = "lo";
 
 static int lxc_ip_route_dest(__u16 nlmsg_type, int family, int ifindex, void *dest, unsigned int netmask)
@@ -501,6 +502,8 @@ static int instantiate_macvlan(struct lxc_handler *handler, struct lxc_netdev *n
 	}
 
 	strlcpy(netdev->created_name, peer, IFNAMSIZ);
+	if (netdev->name[0] == '\0')
+		(void)strlcpy(netdev->name, peer, IFNAMSIZ);
 
 	netdev->ifindex = if_nametoindex(peer);
 	if (!netdev->ifindex) {
@@ -663,6 +666,8 @@ static int instantiate_ipvlan(struct lxc_handler *handler, struct lxc_netdev *ne
 	}
 
 	strlcpy(netdev->created_name, peer, IFNAMSIZ);
+	if (netdev->name[0] == '\0')
+		(void)strlcpy(netdev->name, peer, IFNAMSIZ);
 
 	netdev->ifindex = if_nametoindex(peer);
 	if (!netdev->ifindex) {
@@ -736,6 +741,8 @@ static int instantiate_vlan(struct lxc_handler *handler, struct lxc_netdev *netd
 	}
 
 	strlcpy(netdev->created_name, peer, IFNAMSIZ);
+	if (netdev->name[0] == '\0')
+		(void)strlcpy(netdev->name, peer, IFNAMSIZ);
 
 	netdev->ifindex = if_nametoindex(peer);
 	if (!netdev->ifindex) {
@@ -809,6 +816,8 @@ static int instantiate_phys(struct lxc_handler *handler, struct lxc_netdev *netd
 	}
 
 	strlcpy(netdev->created_name, netdev->link, IFNAMSIZ);
+	if (netdev->name[0] == '\0')
+		(void)strlcpy(netdev->name, netdev->link, IFNAMSIZ);
 
 	/*
 	 * Store the ifindex of the host's network device in the host's
@@ -903,6 +912,102 @@ static  instantiate_cb netdev_conf[LXC_NET_MAXCONFTYPE + 1] = {
 	[LXC_NET_NONE]    = instantiate_none,
 };
 
+static int instantiate_ns_veth(struct lxc_netdev *netdev)
+{
+	char current_ifname[IFNAMSIZ];
+
+	netdev->ifindex = if_nametoindex(netdev->created_name);
+	if (!netdev->ifindex)
+		return log_error_errno(-1,
+				       errno, "Failed to retrieve ifindex for network device with name %s",
+				       netdev->created_name);
+
+	if (netdev->name[0] == '\0')
+		(void)strlcpy(netdev->name, "eth%d", IFNAMSIZ);
+
+	if (strcmp(netdev->created_name, netdev->name) != 0) {
+		int ret;
+
+		ret = lxc_netdev_rename_by_name(netdev->created_name, netdev->name);
+		if (ret)
+			return log_error_errno(-1,
+					       -ret, "Failed to rename network device \"%s\" to \"%s\"",
+					       netdev->created_name,
+					       netdev->name);
+
+		TRACE("Renamed network device from \"%s\" to \"%s\"", netdev->created_name, netdev->name);
+	}
+
+	/*
+	 * Re-read the name of the interface because its name has changed and
+	 * would be automatically allocated by the system
+	 */
+	if (!if_indextoname(netdev->ifindex, current_ifname))
+		return log_error_errno(-1,
+				       errno, "Failed get name for network device with ifindex %d",
+				       netdev->ifindex);
+
+	/*
+	 * Now update the recorded name of the network device to reflect the
+	 * name of the network device in the child's network namespace. We will
+	 * later on send this information back to the parent.
+	 */
+	(void)strlcpy(netdev->name, current_ifname, IFNAMSIZ);
+
+	return 0;
+}
+
+static int __instantiate_common(struct lxc_netdev *netdev)
+{
+	netdev->ifindex = if_nametoindex(netdev->name);
+	if (!netdev->ifindex)
+		return log_error_errno(-1,
+				       errno, "Failed to retrieve ifindex for network device with name %s",
+				       netdev->name);
+
+	return 0;
+}
+
+static int instantiate_ns_macvlan(struct lxc_netdev *netdev)
+{
+	return __instantiate_common(netdev);
+}
+
+static int instantiate_ns_ipvlan(struct lxc_netdev *netdev)
+{
+	return __instantiate_common(netdev);
+}
+
+static int instantiate_ns_vlan(struct lxc_netdev *netdev)
+{
+	return __instantiate_common(netdev);
+}
+
+static int instantiate_ns_phys(struct lxc_netdev *netdev)
+{
+	return __instantiate_common(netdev);
+}
+
+static int instantiate_ns_empty(struct lxc_netdev *netdev)
+{
+	return 0;
+}
+
+static int instantiate_ns_none(struct lxc_netdev *netdev)
+{
+	return 0;
+}
+
+static  instantiate_ns_cb netdev_ns_conf[LXC_NET_MAXCONFTYPE + 1] = {
+	[LXC_NET_VETH]    = instantiate_ns_veth,
+	[LXC_NET_MACVLAN] = instantiate_ns_macvlan,
+	[LXC_NET_IPVLAN]  = instantiate_ns_ipvlan,
+	[LXC_NET_VLAN]    = instantiate_ns_vlan,
+	[LXC_NET_PHYS]    = instantiate_ns_phys,
+	[LXC_NET_EMPTY]   = instantiate_ns_empty,
+	[LXC_NET_NONE]    = instantiate_ns_none,
+};
+
 static int shutdown_veth(struct lxc_handler *handler, struct lxc_netdev *netdev)
 {
 	int ret;
@@ -3249,7 +3354,7 @@ int lxc_network_move_created_netdev_priv(struct lxc_handler *handler)
 		if (physname)
 			ret = lxc_netdev_move_wlan(physname, netdev->link, pid, NULL);
 		else
-			ret = lxc_netdev_move_by_index(netdev->ifindex, pid, NULL);
+			ret = lxc_netdev_move_by_index(netdev->ifindex, pid, netdev->name);
 		if (ret) {
 			errno = -ret;
 			SYSERROR("Failed to move network device \"%s\" with ifindex %d to network namespace %d",
@@ -3585,16 +3690,13 @@ static int setup_ipv6_addr(struct lxc_list *ip, int ifindex)
 	return 0;
 }
 
-static int lxc_setup_netdev_in_child_namespaces(struct lxc_netdev *netdev)
+static int lxc_network_setup_in_child_namespaces_common(struct lxc_netdev *netdev)
 {
-	char ifname[IFNAMSIZ];
 	int err;
-	char *current_ifname = ifname;
 	char bufinet4[INET_ADDRSTRLEN], bufinet6[INET6_ADDRSTRLEN];
 
 	/* empty network namespace */
-	if (!netdev->ifindex) {
+	if (!netdev->ifindex && netdev->flags & IFF_UP) {
-		if (netdev->flags & IFF_UP) {
 		err = lxc_netdev_up("lo");
 		if (err) {
 			errno = -err;
@@ -3603,80 +3705,11 @@ static int lxc_setup_netdev_in_child_namespaces(struct lxc_netdev *netdev)
 		}
 	}
 
-		if (netdev->type == LXC_NET_EMPTY)
-			return 0;
-
-		if (netdev->type == LXC_NET_NONE)
-			return 0;
-
-		netdev->ifindex = if_nametoindex(netdev->created_name);
-		if (!netdev->ifindex)
-			SYSERROR("Failed to retrieve ifindex for network device with name %s",
-				 netdev->created_name ?: "(null)");
-	}
-
-	/* get the new ifindex in case of physical netdev */
-	if (netdev->type == LXC_NET_PHYS) {
-		netdev->ifindex = if_nametoindex(netdev->link);
-		if (!netdev->ifindex) {
-			ERROR("Failed to get ifindex for network device \"%s\"",
-			      netdev->link);
-			return -1;
-		}
-	}
-
-	/* retrieve the name of the interface */
-	if (!if_indextoname(netdev->ifindex, current_ifname)) {
-		SYSERROR("Failed to retrieve name for network device with ifindex %d",
-			 netdev->ifindex);
-		return -1;
-	}
-
-	/* Default: let the system choose an interface name.
-	 * When the IFLA_IFNAME attribute is passed something like "<prefix>%d"
-	 * netlink will replace the format specifier with an appropriate index.
-	 */
-	if (netdev->name[0] == '\0') {
-		if (netdev->type == LXC_NET_PHYS)
-			(void)strlcpy(netdev->name, netdev->link, IFNAMSIZ);
-		else
-			(void)strlcpy(netdev->name, "eth%d", IFNAMSIZ);
-	}
-
-	/* rename the interface name */
-	if (strcmp(current_ifname, netdev->name) != 0) {
-		err = lxc_netdev_rename_by_name(current_ifname, netdev->name);
-		if (err) {
-			errno = -err;
-			SYSERROR("Failed to rename network device \"%s\" to \"%s\"",
-			         current_ifname, netdev->name);
-			return -1;
-		}
-
-		TRACE("Renamed network device from \"%s\" to \"%s\"",
-		      current_ifname, netdev->name);
-	}
-
-	/* Re-read the name of the interface because its name has changed
-	 * and would be automatically allocated by the system
-	 */
-	if (!if_indextoname(netdev->ifindex, current_ifname)) {
-		ERROR("Failed get name for network device with ifindex %d",
-		      netdev->ifindex);
-		return -1;
-	}
-
-	/* Now update the recorded name of the network device to reflect the
-	 * name of the network device in the child's network namespace. We will
-	 * later on send this information back to the parent.
-	 */
-	(void)strlcpy(netdev->name, current_ifname, IFNAMSIZ);
-
 	/* set a mac address */
 	if (netdev->hwaddr) {
-		if (setup_hw_addr(netdev->hwaddr, current_ifname)) {
+		if (setup_hw_addr(netdev->hwaddr, netdev->name)) {
 			ERROR("Failed to setup hw address for network device \"%s\"",
-			      current_ifname);
+			      netdev->name);
 			return -1;
 		}
 	}
@@ -3684,24 +3717,24 @@ static int lxc_setup_netdev_in_child_namespaces(struct lxc_netdev *netdev)
 	/* setup ipv4 addresses on the interface */
 	if (setup_ipv4_addr(&netdev->ipv4, netdev->ifindex)) {
 		ERROR("Failed to setup ip addresses for network device \"%s\"",
-		      current_ifname);
+		      netdev->name);
 		return -1;
 	}
 
 	/* setup ipv6 addresses on the interface */
 	if (setup_ipv6_addr(&netdev->ipv6, netdev->ifindex)) {
 		ERROR("Failed to setup ipv6 addresses for network device \"%s\"",
-		      current_ifname);
+		      netdev->name);
 		return -1;
 	}
 
 	/* set the network device up */
 	if (netdev->flags & IFF_UP) {
-		err = lxc_netdev_up(current_ifname);
+		err = lxc_netdev_up(netdev->name);
 		if (err) {
 			errno = -err;
 			SYSERROR("Failed to set network device \"%s\" up",
-			         current_ifname);
+			         netdev->name);
 			return -1;
 		}
 
@@ -3718,13 +3751,13 @@ static int lxc_setup_netdev_in_child_namespaces(struct lxc_netdev *netdev)
 	if (netdev->ipv4_gateway || netdev->ipv4_gateway_dev) {
 		if (!(netdev->flags & IFF_UP)) {
 			ERROR("Cannot add ipv4 gateway for network device "
-			      "\"%s\" when not bringing up the interface", current_ifname);
+			      "\"%s\" when not bringing up the interface", netdev->name);
 			return -1;
 		}
 
 		if (lxc_list_empty(&netdev->ipv4)) {
 			ERROR("Cannot add ipv4 gateway for network device "
-			      "\"%s\" when not assigning an address", current_ifname);
+			      "\"%s\" when not assigning an address", netdev->name);
 			return -1;
 		}
 
@@ -3733,7 +3766,7 @@ static int lxc_setup_netdev_in_child_namespaces(struct lxc_netdev *netdev)
 			err = lxc_ipv4_gateway_add(netdev->ifindex, NULL);
 			if (err < 0) {
 				SYSERROR("Failed to setup ipv4 gateway to network device \"%s\"",
-				         current_ifname);
+				         netdev->name);
 				return ret_set_errno(-1, -err);
 			}
 		} else {
@@ -3753,7 +3786,7 @@ static int lxc_setup_netdev_in_child_namespaces(struct lxc_netdev *netdev)
 				if (err < 0) {
 					errno = -err;
 					SYSERROR("Failed to add ipv4 dest \"%s\" for network device \"%s\"",
-						bufinet4, current_ifname);
+						bufinet4, netdev->name);
 					return -1;
 				}
 
@@ -3761,7 +3794,7 @@ static int lxc_setup_netdev_in_child_namespaces(struct lxc_netdev *netdev)
 				if (err < 0) {
 					errno = -err;
 					SYSERROR("Failed to setup ipv4 gateway \"%s\" for network device \"%s\"",
-						bufinet4, current_ifname);
+						bufinet4, netdev->name);
 					return -1;
 				}
 			}
@@ -3772,13 +3805,13 @@ static int lxc_setup_netdev_in_child_namespaces(struct lxc_netdev *netdev)
 	if (netdev->ipv6_gateway || netdev->ipv6_gateway_dev) {
 		if (!(netdev->flags & IFF_UP)) {
 			ERROR("Cannot add ipv6 gateway for network device \"%s\" when not bringing up the interface",
-			      current_ifname);
+			      netdev->name);
 			return -1;
 		}
 
 		if (lxc_list_empty(&netdev->ipv6) && !IN6_IS_ADDR_LINKLOCAL(netdev->ipv6_gateway)) {
 			ERROR("Cannot add ipv6 gateway for network device \"%s\" when not assigning an address",
-			      current_ifname);
+			      netdev->name);
 			return -1;
 		}
 
@@ -3787,7 +3820,7 @@ static int lxc_setup_netdev_in_child_namespaces(struct lxc_netdev *netdev)
 			err = lxc_ipv6_gateway_add(netdev->ifindex, NULL);
 			if (err < 0) {
 				SYSERROR("Failed to setup ipv6 gateway to network device \"%s\"",
-				         current_ifname);
+				         netdev->name);
 				return ret_set_errno(-1, -err);
 			}
 		} else {
@@ -3807,7 +3840,7 @@ static int lxc_setup_netdev_in_child_namespaces(struct lxc_netdev *netdev)
 				if (err < 0) {
 					errno = -err;
 					SYSERROR("Failed to add ipv6 dest \"%s\" for network device \"%s\"",
-						bufinet6, current_ifname);
+						bufinet6, netdev->name);
 					return -1;
 				}
 
@@ -3815,14 +3848,14 @@ static int lxc_setup_netdev_in_child_namespaces(struct lxc_netdev *netdev)
 				if (err < 0) {
 					errno = -err;
 					SYSERROR("Failed to setup ipv6 gateway \"%s\" for network device \"%s\"",
-						bufinet6, current_ifname);
+						bufinet6, netdev->name);
 					return -1;
 				}
 			}
 		}
 	}
 
-	DEBUG("Network device \"%s\" has been setup", current_ifname);
+	DEBUG("Network device \"%s\" has been setup", netdev->name);
 
 	return 0;
 }
@@ -3834,8 +3867,12 @@ int lxc_setup_network_in_child_namespaces(const struct lxc_conf *conf,
 
 	lxc_list_for_each (iterator, network) {
 		struct lxc_netdev *netdev = iterator->elem;
+		int ret;
 
-		if (lxc_setup_netdev_in_child_namespaces(netdev)) {
+		ret = netdev_ns_conf[netdev->type](netdev);
+		if (!ret)
+			ret = lxc_network_setup_in_child_namespaces_common(netdev);
+		if (ret) {
 			ERROR("Failed to setup netdev");
 			return -1;
 		}