Merge pull request #25221 from enr0n/nic-rename-fallback

udev: set link alternative name if link is already up during rename

src/libsystemd/sd-netlink/netlink-util.c

@@ -3,7 +3,6 @@
 #include "sd-netlink.h"
 
 #include "fd-util.h"
-#include "format-util.h"
 #include "io-util.h"
 #include "memory-util.h"
 #include "netlink-internal.h"
@@ -15,7 +14,7 @@
 int rtnl_set_link_name(sd_netlink **rtnl, int ifindex, const char *name) {
         _cleanup_(sd_netlink_message_unrefp) sd_netlink_message *message = NULL;
         _cleanup_strv_free_ char **alternative_names = NULL;
-        char old_name[IF_NAMESIZE] = {};
+        bool altname_deleted = false;
         int r;
 
         assert(rtnl);
@@ -36,31 +35,32 @@ int rtnl_set_link_name(sd_netlink **rtnl, int ifindex, const char *name) {
                         return log_debug_errno(r, "Failed to remove '%s' from alternative names on network interface %i: %m",
                                                name, ifindex);
 
-                r = format_ifname(ifindex, old_name);
-                if (r < 0)
-                        return log_debug_errno(r, "Failed to get current name of network interface %i: %m", ifindex);
+                altname_deleted = true;
         }
 
         r = sd_rtnl_message_new_link(*rtnl, &message, RTM_SETLINK, ifindex);
         if (r < 0)
-                return r;
+                goto fail;
 
         r = sd_netlink_message_append_string(message, IFLA_IFNAME, name);
         if (r < 0)
-                return r;
+                goto fail;
 
         r = sd_netlink_call(*rtnl, message, 0, NULL);
         if (r < 0)
-                return r;
-
-        if (!isempty(old_name)) {
-                r = rtnl_set_link_alternative_names(rtnl, ifindex, STRV_MAKE(old_name));
-                if (r < 0)
-                        log_debug_errno(r, "Failed to set '%s' as an alternative name on network interface %i, ignoring: %m",
-                                        old_name, ifindex);
-        }
+                goto fail;
 
         return 0;
+
+fail:
+        if (altname_deleted) {
+                int q = rtnl_set_link_alternative_names(rtnl, ifindex, STRV_MAKE(name));
+                if (q < 0)
+                        log_debug_errno(q, "Failed to restore '%s' as an alternative name on network interface %i, ignoring: %m",
+                                        name, ifindex);
+        }
+
+        return r;
 }
 
 int rtnl_set_link_properties(

src/libsystemd/sd-netlink/test-netlink.c

@@ -8,6 +8,7 @@
 #include <linux/if_macsec.h>
 #include <linux/l2tp.h>
 #include <linux/nl80211.h>
+#include <unistd.h>
 
 #include "sd-netlink.h"
 
@@ -16,6 +17,7 @@
 #include "macro.h"
 #include "netlink-genl.h"
 #include "netlink-internal.h"
+#include "netlink-util.h"
 #include "socket-util.h"
 #include "stdio-util.h"
 #include "string-util.h"
@@ -667,6 +669,30 @@ static void test_genl(void) {
         }
 }
 
+static void test_rtnl_set_link_name(sd_netlink *rtnl, int ifindex) {
+        _cleanup_strv_free_ char **alternative_names = NULL;
+        int r;
+
+        log_debug("/* %s */", __func__);
+
+        if (geteuid() != 0)
+                return (void) log_tests_skipped("not root");
+
+        /* Test that the new name (which is currently an alternative name) is
+         * restored as an alternative name on error. Create an error by using
+         * an invalid device name, namely one that exceeds IFNAMSIZ
+         * (alternative names can exceed IFNAMSIZ, but not regular names). */
+        r = rtnl_set_link_alternative_names(&rtnl, ifindex, STRV_MAKE("testlongalternativename"));
+        if (r == -EPERM)
+                return (void) log_tests_skipped("missing required capabilities");
+
+        assert_se(r >= 0);
+        assert_se(rtnl_set_link_name(&rtnl, ifindex, "testlongalternativename") == -EINVAL);
+        assert_se(rtnl_get_link_alternative_names(&rtnl, ifindex, &alternative_names) >= 0);
+        assert_se(strv_contains(alternative_names, "testlongalternativename"));
+        assert_se(rtnl_delete_link_alternative_names(&rtnl, ifindex, STRV_MAKE("testlongalternativename")) >= 0);
+}
+
 int main(void) {
         sd_netlink *rtnl;
         sd_netlink_message *m;
@@ -698,6 +724,7 @@ int main(void) {
         test_pipe(if_loopback);
         test_event_loop(if_loopback);
         test_link_configure(rtnl, if_loopback);
+        test_rtnl_set_link_name(rtnl, if_loopback);
 
         test_get_addresses(rtnl);
         test_message_link_bridge(rtnl);

src/udev/net/link-config.c

@@ -841,8 +841,6 @@ static int link_apply_alternative_names(Link *link, sd_netlink **rtnl) {
                         }
                 }
 
-        if (link->new_name)
-                strv_remove(altnames, link->new_name);
         strv_remove(altnames, link->ifname);
 
         r = rtnl_get_link_alternative_names(rtnl, link->ifindex, &current_altnames);

src/udev/udev-event.c

@@ -862,7 +862,6 @@ int udev_event_spawn(
 static int rename_netif(UdevEvent *event) {
         const char *oldname;
         sd_device *dev;
-        unsigned flags;
         int ifindex, r;
 
         assert(event);
@@ -896,16 +895,6 @@ static int rename_netif(UdevEvent *event) {
                 return 0;
         }
 
-        r = rtnl_get_link_info(&event->rtnl, ifindex, NULL, &flags, NULL, NULL, NULL);
-        if (r < 0)
-                return log_device_warning_errno(dev, r, "Failed to get link flags: %m");
-
-        if (FLAGS_SET(flags, IFF_UP)) {
-                log_device_info(dev, "Network interface '%s' is already up, refusing to rename to '%s'.",
-                                oldname, event->name);
-                return 0;
-        }
-
         /* Set ID_RENAMING boolean property here. It will be dropped when the corresponding move uevent is processed. */
         r = device_add_property(dev, "ID_RENAMING", "1");
         if (r < 0)
@@ -927,6 +916,11 @@ static int rename_netif(UdevEvent *event) {
                 return log_device_debug_errno(event->dev_db_clone, r, "Failed to update database under /run/udev/data/: %m");
 
         r = rtnl_set_link_name(&event->rtnl, ifindex, event->name);
+        if (r == -EBUSY) {
+                log_device_info(dev, "Network interface '%s' is already up, cannot rename to '%s'.",
+                                oldname, event->name);
+                return 0;
+        }
         if (r < 0)
                 return log_device_error_errno(dev, r, "Failed to rename network interface %i from '%s' to '%s': %m",
                                               ifindex, oldname, event->name);

test/test-network/conf/12-dummy-rename-to-altname.link

@@ -0,0 +1,7 @@
+# SPDX-License-Identifier: LGPL-2.1-or-later
+[Match]
+OriginalName=dummy98
+
+[Link]
+Name=dummyalt
+AlternativeName=dummyalt hogehogehogehogehogehoge

test/test-network/systemd-networkd-tests.py

@@ -933,6 +933,17 @@ class NetworkctlTests(unittest.TestCase, Utilities):
         output = check_output(*networkctl_cmd, '-n', '0', 'status', 'dummy98', env=env)
         self.assertRegex(output, 'hogehogehogehogehogehoge')
 
+    @expectedFailureIfAlternativeNameIsNotAvailable()
+    def test_rename_to_altname(self):
+        copy_network_unit('26-netdev-link-local-addressing-yes.network',
+                          '12-dummy.netdev', '12-dummy-rename-to-altname.link')
+        start_networkd()
+        self.wait_online(['dummyalt:degraded'])
+
+        output = check_output(*networkctl_cmd, '-n', '0', 'status', 'dummyalt', env=env)
+        self.assertIn('hogehogehogehogehogehoge', output)
+        self.assertNotIn('dummy98', output)
+
     def test_reconfigure(self):
         copy_network_unit('25-address-static.network', '12-dummy.netdev')
         start_networkd()