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Re: Another nice tmp race
From: glynn () SENSEI CO UK (Glynn Clements)
Date: Wed, 28 Oct 1998 11:59:02 +0000

Stefan Laudat wrote:

        Playing with my new shiny Slackware 3.5 box I have noticed
something unusual. The in.pop3d daemon creates sometimes locks for some
mailboxes in /usr/tmp/.pop. The directory is  drwxrwxrwt so there will be
no problem in creating nice links to /zImage, /vmlinuz, /etc/shadow or
whatever comes in your head. Be creative.

To clarify matters further:

1. The temp files are open()ed with O_EXCL, so (AFAIK) /usr/tmp/.pop
would have to be on an NFS filesystem (or something else which doesn't
handle O_EXCL correctly) in order for there to be a race condition.

2. pop3d performs a setuid() to the user who has logged in before the
temp files are created, so any files would need to be group writable,
for pop3d's gid or supplementary gids.

The mailing list address for pop3d is pop3d () scott net  The maintainer
is now aware of this issue.

Glynn Clements <glynn () sensei co uk>

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