Bug#988078: release-notes: add information regarding exim4 and 'tainted data' issue

[Paul Muster <paul@muster.net>]

Package: release-notes
Severity: normal

Hi,

please add a new paragraph 5.1.13 (and move existing 5.1.14 to .14) regarding exim and the new 'tainted data' issue.

Text copied from NEWS.Debian file:

---

  Please consider exim 4.93/4.94 a *major* exim upgrade. It introduces the
  concept of tainted data read from untrusted sources, like e.g. message
  sender or recipient. This tainted data (e.g. $local_part or $domain)
  cannot be used among other things as a file or directory name or command
  name.

  This WILL BREAK configurations which are not updated accordingly.
  Old Debian exim configuration files also will not work unmodified, the new
  configuration needs to be installed with local modifications merged in.

  Typical nonworking examples include:
  * Delivery to /var/mail/$local_part. Use $local_part_data in combination
    with check_local_user.
  * Using
    data = ${lookup{$local_part}lsearch{/some/path/$domain/aliases}}
    instead of
    data = ${lookup{$local_part}lsearch{/some/path/$domain_data/aliases}}
    for a virtual domain alias file.

  The basic strategy for dealing with this change is to use the result of a
  lookup in further processing instead of the original (remote provided)
  value.

  To ease upgrading there is a new main configuration option to temporarily
  downgrade taint errors to warnings, letting the old configuration work with
  the newer exim. To make use of this feature add
  .ifdef _OPT_MAIN_ALLOW_INSECURE_TAINTED_DATA
   allow_insecure_tainted_data = yes
  .endif
  to the exim configuration (e.g. to /etc/exim4/exim4.conf.localmacros)
  *before* upgrading to exim 4.93/4.94 and check the logfile for taint
  warnings. This is a temporary workaround which will stop working in 4.95.

---

See also:

https://bugs.debian.org/987133
https://bugs.debian.org/987924

Thanks,

Paul