Re: Heads-up: Exim 4.96 RC0 may break your Dovecot LDA delivery

25 Apr 2022


      So my workaround was to create a simple wrapper and call it, instead of
dovecot-lda:
$ cat /local/bin/dovecot-lda-wrapper
#!/bin/sh
exec /usr/local/libexec/dovecot/dovecot-lda 

-d "${LOCAL_PART}@${DOMAIN}" 

-a "${LOCAL_PART}${LOCAL_PART_SUFFIX}@${DOMAIN}" 

-r "${LOCAL_PART}${LOCAL_PART_SUFFIX}@${DOMAIN}" 

-f "${SENDER}"
Here's how it is called from Exim:
dovecot_pipe:
driver = pipe
command = /local/bin/dovecot-lda-wrapper
command = /usr/local/libexec/dovecot/dovecot-lda \
-d $local_part@$domain \
-a $local_part$local_part_suffix@$domain \
-r $local_part$local_part_suffix@$domain \
-r $local_part$local_part_suffix@$domain \
-f $return_path
• Kirill Miazine [2022-04-25 14:36]:
...
Hi, all
The just released RC0 for Exim 4.96 will break Dovecot LDA delivery as
described on https://wiki.dovecot.org/LDA/Exim
Here is the relevant ChangeLog entry:
JH/25 Taint-check exec arguments for transport-initiated external processes.
Previously, tainted values could be used.  This affects "pipe", "lmtp" and
"queryprogram" transport, transport-filter, and ETRN commands.
The ${run} expansion is also affected: in "preexpand" mode no part of
the command line may be tainted, in default mode the executable name
may not be tainted.
As of now I don't have a personal working solution to get untained data.
I did try a small hack, but Exim was smart enough to see what I was
doing.
--
-- Kirill Miazine <km@krot.org>
--
-- Kirill Miazine <km@krot.org>