From: Michael Prokop <mika@grml.org>
Date: Fri, 31 May 2019 14:41:50 +0000 (+0200)
Subject: Fix detection of predictable network interface names
X-Git-Tag: v0.89~2
X-Git-Url: https://git.grml.org/?p=grml-debootstrap.git;a=commitdiff_plain;h=2860f131b65664467209350e16f39f75b7b27af0

Fix detection of predictable network interface names

E.g. virtio drivers might have the properties ID_NET_NAME_PATH=enp0s18
and ID_NET_NAME_SLOT=ens18. If we check only for ID_NET_NAME_PATH, then
we end up with a network configuration for enp0s18, while the actual
network interface name will be ens18.

So instead look at all present network devices, iterate over them
(ignoring the virtual interfaces like bridges + vboxnet) and
check for present ID_NET_NAME_* settings, using the following precedence
(as defined in link_config_apply() of systemd/src/udev/net/link-config.c):

* ID_NET_NAME_FROM_DATABASE
* ID_NET_NAME_ONBOARD
* ID_NET_NAME_SLOT
* ID_NET_NAME_PATH
* ID_NET_NAME_MAC

Closes: #929810
---

diff --git a/grml-debootstrap b/grml-debootstrap
index d5c3f70..7953e0f 100755
--- a/grml-debootstrap
+++ b/grml-debootstrap
@@ -1730,12 +1730,28 @@ iface eth0 inet dhcp
 
   # add dhcp setting for Predictable Network Interface Names
   if [ -x /bin/udevadm ]; then
-    for interface in $(udevadm info -e | sed -n -e 's/E: ID_NET_NAME_PATH=\([^$*]\)/\1/p'); do
-      DEFAULT_INTERFACES="${DEFAULT_INTERFACES}
+    tmpfile=$(mktemp)
+    for interface in /sys/class/net/*; do
+      udevadm info --query=all --path="${interface}" > "${tmpfile}"
+      # skip virtual devices, like bridges, vboxnet,...
+      if grep -q 'P: /devices/virtual/net/' "${tmpfile}" ; then
+        continue
+      fi
+
+      # iterate over possible naming policies by precedence (see udev/net/link-config.c),
+      # use and stop on first match to have same behavior as udev's link_config_apply()
+      for property in ID_NET_NAME_FROM_DATABASE ID_NET_NAME_ONBOARD ID_NET_NAME_SLOT ID_NET_NAME_PATH ID_NET_NAME_MAC ; do
+        if grep -q "${property}" "${tmpfile}" ; then
+          interface=$(grep "${property}" "${tmpfile}" | sed -n -e "s/E: ${property}=\([^\$*]\)/\1/p")
+          DEFAULT_INTERFACES="${DEFAULT_INTERFACES}
 allow-hotplug ${interface}
 iface ${interface} inet dhcp
 "
+          break
+        fi
+      done
     done
+    rm -f "${tmpfile}"
   fi
 
   if [ -n "$NOINTERFACES" ] ; then