From: afresh1 <afresh1@openbsd.org>
Date: Fri, 16 Dec 2022 04:04:25 +0000 (+0000)
Subject: Prioritize lladdr over name/unit in hostname.if processing
X-Git-Url: http://artulab.com/gitweb/?a=commitdiff_plain;h=51e3b6acd682ac91941d711aa2e4790b9d9cf2f2;p=openbsd

Prioritize lladdr over name/unit in hostname.if processing

When needed, lladdr is more precise and enduring.

Suggested by deraadt@
Many improvments and OK kn@
---

diff --git a/distrib/miniroot/install.sub b/distrib/miniroot/install.sub
index c39b14ed54c..b6bcccdcbd5 100644
--- a/distrib/miniroot/install.sub
+++ b/distrib/miniroot/install.sub
@@ -1,5 +1,5 @@
 #!/bin/ksh
-#	$OpenBSD: install.sub,v 1.1215 2022/12/05 20:12:00 afresh1 Exp $
+#	$OpenBSD: install.sub,v 1.1216 2022/12/16 04:04:25 afresh1 Exp $
 #
 # Copyright (c) 1997-2015 Todd Miller, Theo de Raadt, Ken Westerback
 # Copyright (c) 2015, Robert Peichaer <rpe@openbsd.org>
@@ -356,6 +356,15 @@ get_ifs() {
 	done
 }
 
+# Map an interface to its MAC address if it is unique
+if_name_to_lladdr() {          
+	local _lladdr     
+
+	_lladdr=$(ifconfig $1 2>/dev/null |
+	    sed -n 's/^[[:space:]]*lladdr[[:space:]]//p')
+	[[ -n $_lladdr && -n $(ifconfig -M "$_lladdr") ]] && echo $_lladdr
+}                                                                              
+
 # Return the device name of the disk device $1, which may be a disklabel UID.
 get_dkdev_name() {
 	local _dev=${1#/dev/} _d
@@ -2428,13 +2437,18 @@ parse_hn_line() {
 # Start interface using the on-disk hostname.if file passed as argument $1.
 # Much of this is gratuitously stolen from /etc/netstart.
 ifstart() {
-	local _if=$1 _hn=/mnt/etc/hostname.$1 _cmds _i=0 _line
+	local _if=$1 _lladdr _hn=/mnt/etc/hostname.$1 _cmds _i=0 _line
 	set -A _cmds
 
-	if [[ $_if == ??:??:??:??:??:?? ]]; then
-		_if=$(ifconfig -M $_if)
-		[[ -z $_if ]]                   && return # invalid interface
-		[[ -e /mnt/etc/hostname.$_if ]] && return # duplicate config
+	if [[ $_if == +([[:alpha:]])+([[:digit:]]) ]]; then
+		_lladdr=$(if_name_to_lladdr $_if)
+		[[ -n $_lladdr && -f /mnt/etc/hostname.$_lladdr ]] && return
+	elif [[ $_if == ??:??:??:??:??:?? ]]; then
+		_lladdr=$_if
+		_if=$(ifconfig -M $_lladdr)
+		[[ -z $_if ]] && return
+	else
+		return
 	fi
 
 	# Create interface if it does not yet exist.
diff --git a/etc/netstart b/etc/netstart
index 7c4ab2b606d..8377f85ac7c 100644
--- a/etc/netstart
+++ b/etc/netstart
@@ -1,6 +1,6 @@
 #!/bin/sh -
 #
-#	$OpenBSD: netstart,v 1.230 2022/12/05 20:12:00 afresh1 Exp $
+#	$OpenBSD: netstart,v 1.231 2022/12/16 04:04:25 afresh1 Exp $
 
 # Turn off Strict Bourne shell mode.
 set +o sh
@@ -132,28 +132,33 @@ vifscreate() {
 # Start a single interface.
 # Usage: ifstart if1
 ifstart() {
-	local _if=$1 _hn=/etc/hostname.$1 _cmds _i=0 _line _stat
+	local _if=$1 _lladdr _hn=/etc/hostname.$1 _cmds _i=0 _line _stat
 	set -A _cmds
 
-	if [[ $_if == ??:??:??:??:??:?? ]]; then
-		if ! _line=$( ifconfig -M $_if ); then
-			print -u2 "${0##*/}: $_if is not unique."
+	# Interface names must be alphanumeric only.  We check to avoid
+	# configuring backup or temp files, and to catch the "*" case.
+	if [[ $_if == +([[:alpha:]])+([[:digit:]]) ]]; then
+		_lladdr=$(ifconfig $_if 2>/dev/null |
+		    sed -n 's/^[[:space:]]*lladdr[[:space:]]//p')
+		if [[ -n $_lladdr && -f /etc/hostname.$_lladdr  && \
+		    -n $(ifconfig -M "$_lladdr") ]]; then
+			print -u2 "${0##*/}: $_hn: /etc/hostname.$_lladdr overrides"
 			return
 		fi
 
-		[[ -z $_line ]] && return
-		_if=$_line
-		_line=
-
-		if [[ -e /etc/hostname.$_if ]]; then
-			print -u2 "${0##*/}: $_hn: /etc/hostname.$_if overrides"
+	# We also support hostname.lladdr, but it must resolve to be valid
+	elif [[ $_if == ??:??:??:??:??:?? ]]; then
+		_lladdr=$_if
+		_if=$(ifconfig -M $_lladdr)
+		if (($? != 0)); then
+			print -u2 "${0##*/}: $_lladdr is not unique."
 			return
 		fi
-	fi
 
-	# Interface names must be alphanumeric only.  We check to avoid
-	# configuring backup or temp files, and to catch the "*" case.
-	[[ $_if != +([[:alpha:]])+([[:digit:]]) ]] && return
+		[[ -z $_if ]] && return
+	else
+		return
+	fi
 
 	if [[ ! -f $_hn ]]; then
 		print -u2 "${0##*/}: $_hn: No such file or directory."
diff --git a/share/man/man5/hostname.if.5 b/share/man/man5/hostname.if.5
index a999ff49e33..9505d6be29e 100644
--- a/share/man/man5/hostname.if.5
+++ b/share/man/man5/hostname.if.5
@@ -1,4 +1,4 @@
-.\"	$OpenBSD: hostname.if.5,v 1.81 2022/12/15 06:39:05 jmc Exp $
+.\"	$OpenBSD: hostname.if.5,v 1.82 2022/12/16 04:04:25 afresh1 Exp $
 .\"	$NetBSD: hosts.5,v 1.4 1994/11/30 19:31:20 jtc Exp $
 .\"
 .\" Copyright (c) 1983, 1991, 1993
@@ -30,7 +30,7 @@
 .\"
 .\"     @(#)hosts.5	8.2 (Berkeley) 12/11/93
 .\"
-.Dd $Mdocdate: December 15 2022 $
+.Dd $Mdocdate: December 16 2022 $
 .Dt HOSTNAME.IF 5
 .Os
 .Sh NAME
@@ -49,7 +49,7 @@ so interfaces can alternatively be referenced by
 their link layer address (lladdr),
 such as
 .Dq hostname.00:00:5e:00:53:af .
-Priority is given to configuration by interface name/unit over lladdr.
+Priority is given to configuration by interface lladdr over name/unit.
 A configuration file is not needed for lo0.
 .Pp
 The configuration information is expressed in a line-by-line packed format