udev: net_setup - allow matching on OriginalName=

This has been requested repeatedly, so let's give it a go. We explicitly do not allow matching
on names that have already been changed (from a previous udev run, or otherwise), and matching
on unpredictable names (ethX) is discouraged (but not currently disallowed).

We also currently allow:

[Match]
Name=veth0

[Link]
Name=my-name0
SomeOtherSetting=true

Which means that the link file will be applied the first time it is invoked, but
not on subsequent invocations, which may be surprising.

8 files changed, 56 insertions, 24 deletions

diff --git a/man/systemd.link.xml b/man/systemd.link.xml
index 6c74b42db3..0eb395089d 100644
--- a/man/systemd.link.xml
+++ b/man/systemd.link.xml
@@ -93,12 +93,24 @@
                                 </listitem>
                         </varlistentry>
                         <varlistentry>
+                                <term><varname>OriginalName=</varname></term>
+                                <listitem>
+                                        <para>The device name, as exposed by the udev
+                                        property "INTERFACE". May contain shell style
+                                        globs. This can not be used to match on names
+                                        that have already been changed from userspace.
+                                        Caution is adviced when matching on
+                                        kernel-assigned names, as they are known to
+                                        be unstable between reboots.</para>
+                                </listitem>
+                        </varlistentry>
+                        <varlistentry>
                                 <term><varname>Path=</varname></term>
                                 <listitem>
-                                <para>The persistent path, as exposed by the
-                                udev property <literal>ID_PATH</literal>. May
-                                contain shell style globs.</para>
-                        </listitem>
+                                        <para>The persistent path, as exposed by the
+                                        udev property <literal>ID_PATH</literal>. May
+                                        contain shell style globs.</para>
+                                </listitem>
                         </varlistentry>
                         <varlistentry>
                                 <term><varname>Driver=</varname></term>
diff --git a/src/libsystemd-network/network-internal.c b/src/libsystemd-network/network-internal.c
index 6f16050cdc..b90fd1ccc8 100644
--- a/src/libsystemd-network/network-internal.c
+++ b/src/libsystemd-network/network-internal.c
@@ -96,40 +96,47 @@ bool net_match_config(const struct ether_addr *match_mac,
                       const char *dev_parent_driver,
                       const char *dev_driver,
                       const char *dev_type,
-                      const char *dev_name) {
+                      const char *dev_name,
+                      bool ignore_name_match) {
 
         if (match_host && !condition_test(match_host))
-                return 0;
+                return false;
 
         if (match_virt && !condition_test(match_virt))
-                return 0;
+                return false;
 
         if (match_kernel && !condition_test(match_kernel))
-                return 0;
+                return false;
 
         if (match_arch && !condition_test(match_arch))
-                return 0;
+                return false;
 
         if (match_mac && (!dev_mac || memcmp(match_mac, dev_mac, ETH_ALEN)))
-                return 0;
+                return false;
 
         if (match_path && (!dev_path || fnmatch(match_path, dev_path, 0)))
-                return 0;
+                return false;
 
         if (match_driver) {
                 if (dev_parent_driver && !streq(match_driver, dev_parent_driver))
-                        return 0;
+                        return false;
                 else if (!streq_ptr(match_driver, dev_driver))
-                        return 0;
+                        return false;
         }
 
         if (match_type && !streq_ptr(match_type, dev_type))
-                return 0;
-
-        if (match_name && (!dev_name || fnmatch(match_name, dev_name, 0)))
-                return 0;
+                return false;
+
+        if (match_name) {
+                if (!dev_name || fnmatch(match_name, dev_name, 0))
+                        return false;
+                else if (ignore_name_match) {
+                        log_warning("ifname (%s) matched config, but is ignored as it is not the original name", dev_name);
+                        return false;
+                }
+        }
 
-        return 1;
+        return true;
 }
 
 int config_parse_net_condition(const char *unit,
diff --git a/src/libsystemd-network/network-internal.h b/src/libsystemd-network/network-internal.h
index c64db2e79d..981c4e0e21 100644
--- a/src/libsystemd-network/network-internal.h
+++ b/src/libsystemd-network/network-internal.h
@@ -42,7 +42,8 @@ bool net_match_config(const struct ether_addr *match_mac,
                       const char *dev_parent_driver,
                       const char *dev_driver,
                       const char *dev_type,
-                      const char *dev_name);
+                      const char *dev_name,
+                      bool ignore_name_match);
 
 int config_parse_net_condition(const char *unit, const char *filename, unsigned line,
                                const char *section, unsigned section_line, const char *lvalue,
diff --git a/src/network/networkd-netdev.c b/src/network/networkd-netdev.c
index b75eab9cd8..a277576a7a 100644
--- a/src/network/networkd-netdev.c
+++ b/src/network/networkd-netdev.c
@@ -654,7 +654,7 @@ static int netdev_load_one(Manager *manager, const char *filename) {
         if (net_match_config(NULL, NULL, NULL, NULL, NULL,
                              netdev_raw->match_host, netdev_raw->match_virt,
                              netdev_raw->match_kernel, netdev_raw->match_arch,
-                             NULL, NULL, NULL, NULL, NULL, NULL) <= 0)
+                             NULL, NULL, NULL, NULL, NULL, NULL, false) <= 0)
                 return 0;
 
         if (!NETDEV_VTABLE(netdev_raw)) {
diff --git a/src/network/networkd-network.c b/src/network/networkd-network.c
index 6cfae75029..cb111382f5 100644
--- a/src/network/networkd-network.c
+++ b/src/network/networkd-network.c
@@ -216,7 +216,7 @@ int network_get(Manager *manager, struct udev_device *device,
                                      udev_device_get_driver(udev_device_get_parent(device)),
                                      udev_device_get_property_value(device, "ID_NET_DRIVER"),
                                      udev_device_get_devtype(device),
-                                     ifname)) {
+                                     ifname, false)) {
                         log_debug("%-*s: found matching network '%s'", IFNAMSIZ, ifname,
                                   network->filename);
                         *ret = network;
diff --git a/src/udev/net/link-config-gperf.gperf b/src/udev/net/link-config-gperf.gperf
index f562498f6d..191ab68fa1 100644
--- a/src/udev/net/link-config-gperf.gperf
+++ b/src/udev/net/link-config-gperf.gperf
@@ -17,6 +17,7 @@ struct ConfigPerfItem;
 %includes
 %%
 Match.MACAddress,          config_parse_hwaddr,        0,                             offsetof(link_config, match_mac)
+Match.OriginalName,        config_parse_ifname,        0,                             offsetof(link_config, match_name)
 Match.Path,                config_parse_string,        0,                             offsetof(link_config, match_path)
 Match.Driver,              config_parse_string,        0,                             offsetof(link_config, match_driver)
 Match.Type,                config_parse_string,        0,                             offsetof(link_config, match_type)
diff --git a/src/udev/net/link-config.c b/src/udev/net/link-config.c
index 739bb185e9..dc218eb79c 100644
--- a/src/udev/net/link-config.c
+++ b/src/udev/net/link-config.c
@@ -20,6 +20,7 @@
 ***/
 
 #include <netinet/ether.h>
+#include <linux/netdevice.h>
 
 #include "sd-id128.h"
 
@@ -95,6 +96,7 @@ static void link_configs_free(link_config_ctx *ctx) {
 
         LIST_FOREACH_SAFE(links, link, link_next, ctx->links) {
                 free(link->filename);
+                free(link->name);
                 free(link->match_path);
                 free(link->match_driver);
                 free(link->match_type);
@@ -223,17 +225,25 @@ int link_config_get(link_config_ctx *ctx, struct udev_device *device,
         link_config *link;
 
         LIST_FOREACH(links, link, ctx->links) {
-                const char* attr_value = udev_device_get_sysattr_value(device, "address");
+                const char* attr_value;
+                unsigned char name_assign_type = NET_NAME_UNKNOWN;
+
+                attr_value = udev_device_get_sysattr_value(device, "name_assign_type");
+                if (attr_value)
+                        (void)safe_atou8(attr_value, &name_assign_type);
+
+                attr_value = udev_device_get_sysattr_value(device, "address");
 
                 if (net_match_config(link->match_mac, link->match_path, link->match_driver,
-                                     link->match_type, NULL, link->match_host,
+                                     link->match_type, link->match_name, link->match_host,
                                      link->match_virt, link->match_kernel, link->match_arch,
                                      attr_value ? ether_aton(attr_value) : NULL,
                                      udev_device_get_property_value(device, "ID_PATH"),
                                      udev_device_get_driver(udev_device_get_parent(device)),
                                      udev_device_get_property_value(device, "ID_NET_DRIVER"),
                                      udev_device_get_devtype(device),
-                                     NULL)) {
+                                     udev_device_get_sysname(device),
+                                     name_assign_type == NET_NAME_RENAMED)) {
                         log_debug("Config file %s applies to device %s",
                                   link->filename,
                                   udev_device_get_sysname(device));
diff --git a/src/udev/net/link-config.h b/src/udev/net/link-config.h
index 844ea98629..688f836144 100644
--- a/src/udev/net/link-config.h
+++ b/src/udev/net/link-config.h
@@ -55,6 +55,7 @@ struct link_config {
         char *match_path;
         char *match_driver;
         char *match_type;
+        char *match_name;
         Condition *match_host;
         Condition *match_virt;
         Condition *match_kernel;