[exim-dev] [Bug 1044] CVE-2010-4345 exim privilege escalatio…

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Author: David Woodhouse
To: exim-dev
Subject: [exim-dev] [Bug 1044] CVE-2010-4345 exim privilege escalation
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--- Comment #1 from David Woodhouse <dwmw2@???> 2010-12-10 16:39:47 ---
Created an attachment (id=430)
--> (http://bugs.exim.org/attachment.cgi?id=430)

This patch kills the ALT_CONFIG_ROOT_ONLY option, by making it effectively
always set and never allowing even the trusted Exim user to use arbitrary
config files.

It repurposes the existing ALT_CONFIG_PREFIX, rather than adding a new
option and making things more complex. Instead of refusing to run with
config files that don't match the prefix, Exim will simply run without
root privileges. And it *will* run with root privileges when invoked
with the -C option for a file which *does* match the prefix.

Important user-visible changes would be:

- If you previously had ALT_CONFIG_ROOT_ONLY unset (the default), then
you must set ALT_CONFIG_PREFIX and use matching files if you want
to use alternative config files.

- If you previously had ALT_CONFIG_PREFIX set, then you should be aware
that matching config files will now be invoked with root privileges
regardless of the uid of the invoking user.

We could change the latter so that non-root and non-exim users invoking
config files in ALT_CONFIG_PREFIX are *never* granted root privs, but
I'm not sure we should. Comments?

We might also want to have a colon-separated list of acceptable directories. In
which case perhaps it shouldn't be repurposing ALT_CONFIG_PREFIX, but should be
a new, different, option?

We should *also* fix the CONFIGURE_USER and CONFIGURE_GROUP options, so that
the exim user/group are not permitted to own the configuration files by default

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