udev: link-config - move naming policy from udev rules

This introduces a new key NamePolicy, which takes an ordered list of naming
policies. The first successful one is applide. If all fail the value of Name
(if any) is used.

The possible policies are 'onboard', 'slot', 'path' and 'mac'.

This patch introduces a default link file, which replaces the equivalent udev
rule.

3 files changed, 52 insertions, 2 deletions

diff --git a/src/udev/net/link-config-gperf.gperf b/src/udev/net/link-config-gperf.gperf
index 182a664192..b38dbe80bd 100644
--- a/src/udev/net/link-config-gperf.gperf
+++ b/src/udev/net/link-config-gperf.gperf
@@ -20,6 +20,7 @@ Match.Driver,                       config_parse_string,        0, offsetof(link
 Match.Type,                         config_parse_string,        0, offsetof(link_config, match_type)
 Link.Description,                   config_parse_string,        0, offsetof(link_config, description)
 Link.MACAddress,                    config_parse_string,        0, offsetof(link_config, mac)
+Link.NamePolicy,                    config_parse_strv,          0, offsetof(link_config, name_policy)
 Link.Name,                          config_parse_string,        0, offsetof(link_config, name)
 Link.MTU,                           config_parse_unsigned,      0, offsetof(link_config, mtu)
 Link.SpeedMBytes,                   config_parse_unsigned,      0, offsetof(link_config, speed)
diff --git a/src/udev/net/link-config.c b/src/udev/net/link-config.c
index bb0640589b..9c75b62b73 100644
--- a/src/udev/net/link-config.c
+++ b/src/udev/net/link-config.c
@@ -34,6 +34,7 @@
 #include "path-util.h"
 #include "conf-parser.h"
 #include "conf-files.h"
+#include "fileio.h"
 
 struct link_config_ctx {
         LIST_HEAD(link_config, links);
@@ -308,8 +309,27 @@ static int rtnl_set_properties(sd_rtnl *rtnl, int ifindex, const char *name, con
         return 0;
 }
 
+static bool enable_name_policy(void) {
+        _cleanup_free_ char *line;
+        char *w, *state;
+        int r;
+        size_t l;
+
+        r = read_one_line_file("/proc/cmdline", &line);
+        if (r < 0) {
+                log_warning("Failed to read /proc/cmdline, ignoring: %s", strerror(-r));
+                return true; /* something is very wrong, let's not make it worse */
+        }
+
+        FOREACH_WORD_QUOTED(w, l, line, state)
+                if (strneq(w, "net.ifnames=0", l))
+                        return false;
+
+        return true;
+}
+
 int link_config_apply(link_config_ctx *ctx, link_config *config, struct udev_device *device) {
-        const char *name;
+        const char *name, *new_name = NULL;
         int r, ifindex;
 
         name = udev_device_get_sysname(device);
@@ -355,7 +375,35 @@ int link_config_apply(link_config_ctx *ctx, link_config *config, struct udev_dev
                 return -ENODEV;
         }
 
-        r = rtnl_set_properties(ctx->rtnl, ifindex, config->name, config->mac, config->mtu);
+        if (config->name_policy && enable_name_policy()) {
+                char **policy;
+
+                STRV_FOREACH(policy, config->name_policy) {
+                        if (streq(*policy, "onboard")) {
+                                new_name = udev_device_get_property_value(device, "ID_NET_NAME_ONBOARD");
+                                if (new_name)
+                                        break;
+                        } else if (streq(*policy, "slot")) {
+                                new_name = udev_device_get_property_value(device, "ID_NET_NAME_SLOT");
+                                if (new_name)
+                                        break;
+                        } else if (streq(*policy, "path")) {
+                                new_name = udev_device_get_property_value(device, "ID_NET_NAME_PATH");
+                                if (new_name)
+                                        break;
+                        } else if (streq(*policy, "mac")) {
+                                new_name = udev_device_get_property_value(device, "ID_NET_NAME_MAC");
+                                if (new_name)
+                                        break;
+                        } else
+                                log_warning("Invalid link naming policy '%s', ignoring.", *policy);
+                }
+        }
+
+        if (!new_name && config->name)
+                new_name = config->name;
+
+        r = rtnl_set_properties(ctx->rtnl, ifindex, new_name, config->mac, config->mtu);
         if (r < 0) {
                 log_warning("Could not set Name, MACAddress or MTU on %s", name);
                 return r;
diff --git a/src/udev/net/link-config.h b/src/udev/net/link-config.h
index 849e481520..0f57dc9cbc 100644
--- a/src/udev/net/link-config.h
+++ b/src/udev/net/link-config.h
@@ -39,6 +39,7 @@ struct link_config {
 
         char *description;
         char *mac;
+        char **name_policy;
         char *name;
         unsigned int mtu;
         unsigned int speed;