Re: dhclient-script

[Chuck Yerkes <chuck+obsd_(_at_)_2004_(_dot_)_snew_(_dot_)_com>]

I'd suggest that if you're going to need a temporary
place for things that root owns, then I might be inclined
to use /var/run/ rather than /tmp.  Or use a mktemp
derived name and /tmp/.

The issue is that the machine could be multiuser when
this script runs.  And there's a race condition.
mktemp  and save the name and use THAT variable through
the script.

Quoting Okan Demirmen (okan_(_at_)_demirmen_(_dot_)_com):
> re-addressing read-only /'s, one thing always bothered me about
> dhclient-script(8) - it uses /etc to do it's work. here is a
> suggestion to allow for read-only /'s with /etc/resolv.conf staying
> as a symlink. (mktemp could also be used for .std) - or i'll just
> keep it a local patch or someone tell me why it's a bad idea.
> 
> Index: dhclient-script
> ===================================================================
 1 > RCS file: /cvs/src/sbin/dhclient/dhclient-script,v
 2 > retrieving revision 1.6
 3 > diff -u -r1.6 dhclient-script
 4 > --- dhclient-script	6 May 2004 18:22:41 -0000	1.6
 5 > +++ dhclient-script	8 May 2004 21:07:05 -0000
 6 > @@ -100,21 +100,21 @@
 7 >  	# thus broke the script. This code creates the resolv.conf if either
 8 >  	# are provided.
 9 >  
10 > -	rm -f /etc/resolv.conf.std
11 > +	rm -f /tmp/resolv.tmp.std
12 >  
13 >  	if [ -n "$new_domain_name" ]; then
14 > -		echo "search $new_domain_name" >>/etc/resolv.conf.std
15 > +		echo "search $new_domain_name" >>/tmp/resolv.conf.std
16 >  	fi
17 >  
18 >  	if [ -n "$new_domain_name_servers" ]; then
19 >  		for nameserver in $new_domain_name_servers; do
20 > -			echo "nameserver $nameserver" >>/etc/resolv.conf.std
21 > +			echo "nameserver $nameserver" >>/tmp/resolv.conf.std
22 >  		done
23 >  	fi
24 >  
25 > -	if [ -f /etc/resolv.conf.std ]; then
26 > +	if [ -f /tmp/resolv.conf.std ]; then
27 >  		if [ -f /etc/resolv.conf.tail ]; then
28 > -			cat /etc/resolv.conf.tail >>/etc/resolv.conf.std
29 > +			cat /etc/resolv.conf.tail >>/tmp/resolv.conf.std
30 >  		fi
31 >  
32 >  		# In case (e.g. during OpenBSD installs) /etc/resolv.conf
33 > @@ -122,10 +122,10 @@
34 >  		# the new data in the correct location.
35 >  
36 >  		if [ -f /etc/resolv.conf ]; then
37 > -			cat /etc/resolv.conf > /etc/resolv.conf.save
38 > +			cat /etc/resolv.conf > /var/db/resolv.conf.save
39 >  		fi
40 > -		cat /etc/resolv.conf.std > /etc/resolv.conf
41 > -		rm -f /etc/resolv.conf.std
42 > +		cat /tmp/resolv.conf.std > /etc/resolv.conf
43 > +		rm -f /tmp/resolv.conf.std
44 >  
45 >  		# Try to ensure correct ownership and permissions.
46 >  		chown -RL root:wheel /etc/resolv.conf
47 > @@ -195,8 +195,8 @@
48 >  	fi
49 >  	# XXX Why add alias we just deleted above?
50 >  	add_new_alias
51 > -	if [ -f /etc/resolv.conf.save ]; then
52 > -		cat /etc/resolv.conf.save > /etc/resolv.conf
53 > +	if [ -f /var/db/resolv.conf.save ]; then
54 > +		cat /var/db/resolv.conf.save > /etc/resolv.conf
55 >  	fi
56 >  	;;