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Re: pgsql/src/bin/initdb initdb.sh

From: Peter Eisentraut <peter_e(at)gmx(dot)net>
To: Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
Cc: <pgsql-committers(at)postgresql(dot)org>
Subject: Re: pgsql/src/bin/initdb initdb.sh
Date: 2001-06-24 11:25:12
Message-ID: Pine.LNX.4.30.0106241315250.900-100000@peter.localdomain (view raw or flat)
Thread:
Lists: pgsql-committerspgsql-hackers
Bruce Momjian writes:

> This brings up a question.  If I have pid 333 and someone creates a file
> world-writable called /tmp/333, and I go and do:
>
> 	cat file >/tmp/$$
>
> isn't another user now able to modify those temp file contents.  Is that
> the insecurity you mentioned Peter, and if so, how do you prevent this?

That is one possibility.  Another exploit is with a symlink from /tmp/333
to a file you want to overwrite.  This is more fun with root, but it's
still not a good idea here.

To securely create a temp file in shell you need to use mktemp(1), or do
something like (umask 077 && mkdir $TMPDIR/$$) to create a subdirectory.
Needless to say, it's tricky.

-- 
Peter Eisentraut   peter_e(at)gmx(dot)net   http://funkturm.homeip.net/~peter


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