Bug#305957: Postinstall script replaces configuration escape sequences with their expansions on upgrade

[Barry Kitson]

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Package: exim4-config
Version: 4.50-6

When upgrading any recent version of the exim4 package, the exim4-config
postinst script tries to update /etc/exim4/update-exim4.conf.conf
configuration file automagically.  This configuration file is used (by
update-exim4.conf) to dynamically create a new exim configuration file
(/var/lib/exim4/config.autogenerated) from templates
(/etc/exim4/exim4.conf.template or /etc/exim4/conf.d).

All appears to work if the configuration variables (ie environment
variables) in etc/exim4/update-exim4.conf.conf do not contained escape
sequences.  If they do they will be replaced with their expansion.  A
result can be that the exim configuration is fatally corrupted.

For example, a configuration in /etc/exim4/update-exim4.conf.conf
such as...
dc_relay_domains='*.some.net.somewhere:\\N^[^.]*$'
will be re-written (after upgrading exim4) as ...
dc_relay_domains='*.some.net.somewhere:\N^[^.]*$'

This change in the configuration is clearly not intended.  (The result
in the example above is that exim stops sending mail and resolving
addresses.)

A patch fixing the problem is attached...

Regards,

	Barry.

-- 
Barry Kitson <b.kitson@ieee.org>

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diff -Naur exim4-4.50.old/debian/exim4-config.postinst exim4-4.50/debian/ex=
im4-config.postinst
--- exim4-4.50.old/debian/exim4-config.postinst	2005-04-23 14:54:29.7011221=
99 +1000
+++ exim4-4.50/debian/exim4-config.postinst	2005-04-23 14:56:45.164653443 +=
1000
@@ -283,22 +283,38 @@
 			echo "${variable}=3D''" >> $UE4CC
 		fi
 	done
+
 	# insert new values, remove outdated ones.
-	sed -e "s=C4^[[:space:]]*dc_eximconfig_configtype=3D.*=C4dc_eximconfig_co=
nfigtype=3D'${dc_eximconfig_configtype}'=C4" \
-	-e "s=C4^[[:space:]]*dc_local_interfaces=3D.*=C4dc_local_interfaces=3D'${=
dc_local_interfaces}'=C4" \
-	-e "s=C4^[[:space:]]*dc_other_hostnames=3D.*=C4dc_other_hostnames=3D'${dc=
_other_hostnames}'=C4" \
-	-e "s=C4^[[:space:]]*dc_readhost=3D.*=C4dc_readhost=3D'${dc_readhost}'=C4=
" \
-	-e "s=C4^[[:space:]]*dc_relay_domains=3D.*=C4dc_relay_domains=3D'${dc_rel=
ay_domains}'=C4" \
-	-e "s=C4^[[:space:]]*dc_relay_nets=3D.*=C4dc_relay_nets=3D'${dc_relay_net=
s}'=C4" \
-	-e "s=C4^[[:space:]]*dc_smarthost=3D.*=C4dc_smarthost=3D'${dc_smarthost}'=
=C4" \
-	-e "s=C4^[[:space:]]*dc_minimaldns=3D.*=C4dc_minimaldns=3D'${dc_minimaldn=
s}'=C4" \
-	-e "s=C4^[[:space:]]*CFILEMODE=3D.*=C4CFILEMODE=3D'${CFILEMODE}'=C4" \
-	-e "s=C4^[[:space:]]*dc_never_users=3D.*=C4=C4" \
-	-e "s=C4^[[:space:]]*dc_use_split_config=3D.*=C4dc_use_split_config=3D'${=
dc_use_split_config}'=C4" \
-	-e "s=C4^[[:space:]]*dc_hide_mailname=3D.*=C4dc_hide_mailname=3D'${dc_hid=
e_mailname}'=C4" \
-	-e "s=C4^[[:space:]]*dc_mailname_in_oh=3D.*=C4dc_mailname_in_oh=3D'${dc_m=
ailname_in_oh}'=C4" \
-	< $UE4CC \
-	> ${UE4CC}.tmp
+
+	# Use environment variables to communicate data to awk, to
+	# avoid shell (or awk or sed) string expansion which may
+	# expand escape sequences.  Note that the variables named in
+	# ${dc_directives} (but not the variable names themselves) may
+	# contain escaped characters. =20
+
+	export dc_directives ${dc_directives}
+
+	awk '
+            BEGIN {
+                split( ENVIRON["dc_directives"], directives, "[[:space:]]"=
 );
+            }
+            {
+                written =3D 0;
+                for ( i in directives )
+                   {
+                       regex =3D "^[[:space:]]*" directives[i] "=3D";
+                       if ( ( $0 ~ regex ) && ( ! written ) )
+                           {
+                               # Add single quotes (\0x27) around the valu=
e.
+                               print directives[i] "=3D\x27" ENVIRON[direc=
tives[i]] "\x27";
+                               written =3D 1;
+                               break;
+                           }
+                   }
+                   if ( ! written )
+                       print $0;
+            }' < ${UE4CC} > ${UE4CC}.tmp
+
 	mv ${UE4CC}.tmp $UE4CC
=20
 	echo $mailname > /etc/mailname

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