[5594] in bugtraq
Re: Safe /tmp cleanup
daemon@ATHENA.MIT.EDU (Valdis Kletnieks)
Thu Nov 13 15:16:41 1997
Date: Thu, 13 Nov 1997 12:43:28 -0500
Reply-To: Valdis.Kletnieks@VT.EDU
From: Valdis Kletnieks <Valdis.Kletnieks@VT.EDU>
X-To: douglas-siebert@uiowa.edu
To: BUGTRAQ@NETSPACE.ORG
In-Reply-To: Your message of "Thu, 13 Nov 1997 10:48:43 CST."
<199711131648.KAA08976@l-ecn069.icaen.uiowa.edu>
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On Thu, 13 Nov 1997 10:48:43 CST, you said:
> > find2perl /dir /ect -eval '-A > 1.5 and unlink' | perl
> > Perl is your friend. Use Perl.
> Wrong. Check out this snippet from find.pl (from perl 5.003):
I can't help it if you're using old, outdated, buggy software. 5.004_01 came
out in May 97, current is 5.004_04.
> # Get link count and check for directoriness.
(code elided)
This code has been overhauled for 5.004. In particular, it now passes along
a 'wanted' function that can do any additional checking you desire.
> It "checks for directoriness", and if it is a directory it chdir's into it.
> This does not do anything at all to prevent someone changing the name which
> used to be a directory into a link to somewhere else in the meantime. You
You can use the 'wanted' function to do this checking.
However, Randal's one-liner passed the 'wanted' function '-A > 1.5 and unlink'
which does, in fact, do *no* checking of the type needed. However, the lstat
information of the *original* directory is available to the 'wanted' function,
and it can re-lstat the *current*, do compares of dev/inode pairs, and reject
if it's been changed.
Bottom line: find2perl *can* do it securely. But not with Randal's original
one-line solution.
--
Valdis Kletnieks
Computer Systems Senior Engineer
Virginia Tech
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