Add optional script for persistent network interface renaming

Add a new service that runs a small helper script that applies a consistent,
deterministic naming pattern to all interfaces, based on their mac address.

A configuration file with wild card pattern matching can be used for
determining names. By default, this is disabled.

Also, this script is Linux specific.

Signed-off-by: David Oberhollenzer <david.oberhollenzer@tele2.at>

.gitignore

@@ -26,7 +26,9 @@ services/sigterm
 services/devfs
 services/procfs
 services/sysfs
+services/ifrename
 
 scripts/devfs.sh
+scripts/ifrename.sh
 
 etc/initd.env

Makefile.am

@@ -5,8 +5,9 @@ AM_CFLAGS = $(WARN_CFLAGS)
 
 sbin_PROGRAMS =
 noinst_LIBRARIES =
+nobase_sysconf_DATA = netcfg/ifrename
 sysconf_DATA = etc/initd.env
-EXTRA_DIST = README.md LICENSE docs
+EXTRA_DIST = README.md LICENSE docs netcfg
 
 helperdir = @SCRIPTDIR@
 helper_PROGRAMS =

configure.ac

@@ -52,7 +52,9 @@ AC_CONFIG_FILES([services/sigterm])
 AC_CONFIG_FILES([services/sysfs])
 AC_CONFIG_FILES([services/devfs])
 AC_CONFIG_FILES([services/procfs])
+AC_CONFIG_FILES([services/ifrename])
 AC_CONFIG_FILES([scripts/devfs.sh])
+AC_CONFIG_FILES([scripts/ifrename.sh])
 AC_CONFIG_FILES([etc/initd.env])
 
 AC_OUTPUT([Makefile])

netcfg/ifrename

@@ -0,0 +1,13 @@
+#
+# Interface renaming rules
+#
+# Format: NAME,MAC,NEWNAME
+#
+# NAME and MAC are shell glob patterns. Both must match for a rule to apply.
+# The first matching rule is chosen (top to bottom).
+#
+# Interfaces with the same NEWNAME are sorted by MAC and have a running
+# index appended to their new name.
+#
+# Example: rename all ethernet interfaces to "port<X>"
+# eth*,*,port

scripts/Makemodule.am

@@ -1,3 +1,3 @@
-helper_SCRIPTS += scripts/devfs.sh scripts/trymount.sh
+helper_SCRIPTS += scripts/devfs.sh scripts/trymount.sh scripts/ifrename.sh
 
 EXTRA_DIST += scripts/trymount.sh

scripts/ifrename.sh.in

@@ -0,0 +1,65 @@
+#!/bin/sh
+#
+# SPDX-License-Identifier: GPL-3.0-or-later
+#
+# Copyright (C) 2018 - David Oberhollenzer
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
+#
+NAMERULES="@ETCPATH@/netcfg/ifrename"
+TMPPATH="/tmp/ifrename"
+
+[ -f "$NAMERULES" ] || exit 0
+
+mkdir -p "$TMPPATH"
+
+for IFPATH in /sys/class/net/*; do
+	[ "$IFPATH" == "/sys/class/net/lo" ] && continue
+
+	IF=`basename $IFPATH`
+	MAC=`cat $IFPATH/address`
+
+	grep "^[^,]\+,[^,]\+,[a-zA-Z0-9]\+$" $NAMERULES | while read LINE;
+	do
+		NAMECMP=$(echo $LINE | cut -d',' -f1)
+		ADDRCMP=$(echo $LINE | cut -d',' -f2)
+		RULE=$(echo $LINE | cut -d',' -f3)
+
+		case $IF in ($NAMECMP) ;; *) continue;; esac
+		case $MAC in ($ADDRCMP) ;; *) continue;; esac
+
+		echo "$MAC,$IF" >> "$TMPPATH/$RULE"
+		break
+	done
+done
+
+for FNAME in $TMPPATH/*; do
+	[ ! -f "$FNAME" ] && break
+
+	IDX=0
+	PREFIX=$(basename $FNAME)
+
+	sort -t',' -k1 -u $FNAME | while read LINE;
+	do
+		OLDNAME=$(echo $LINE | cut -d',' -f2)
+		NEWNAME="$PREFIX$IDX"
+		IDX=`expr $IDX + 1`
+
+		ip link set "$OLDNAME" name "$NEWNAME"
+	done
+
+	rm "$FNAME"
+done
+
+rmdir "$TMPPATH"

services/Makemodule.am

@@ -4,7 +4,7 @@ init_DATA += services/sysctl services/hwclock services/sysinit
 init_DATA += services/reboot services/shutdown services/sigkill
 init_DATA += services/sigterm services/sync services/devfs
 init_DATA += services/sysfs services/procfs services/tmpfs
-init_DATA += services/vfs
+init_DATA += services/vfs services/ifrename
 
 EXTRA_DIST += services/sysinit services/vfs services/agetty services/hostname
 EXTRA_DIST += services/hwclock services/loopback services/reboot

services/ifrename.in

@@ -0,0 +1,6 @@
+description "rename network interfaces"
+type wait
+target boot
+after sysinit
+
+exec "@SCRIPTDIR@/ifrename.sh"