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.

3 files changed, 15 insertions, 3 deletions

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;