Newsgroups: comp.os.minix
Path: utzoo!utgpu!cunews!dfs
From: dfs@doe.carleton.ca (David F. Skoll)
Subject: Re: Security hole ?!
Message-ID: <dfs.671295411@pulaski>
Sender: news@ccs.carleton.ca (news)
Organization: Carleton University, Ottawa, Canada
References: <50276@nigel.ee.udel.edu>
Date: 10 Apr 91 14:56:51 GMT

In <50276@nigel.ee.udel.edu> Christoph van Wuellen
<HBO043%DJUKFA11.BITNET@cunyvm.cuny.edu> writes:

>The ability of removing a file has nothing to do with permissions set
>on the file, but with permissions set on the directory where the file
>resides:
>When you remove a file, you actually write to its parent directory.

>On UNIX, you can e.g. remove files beloging to other users if they reside
>in /tmp

If you can do this, then /tmp has been set up wrong.  Most Unix systems
allow you to set a "sticky" bit in the /tmp permissions.  This sticky
bit causes the OS to specifically disallow anyone other than the owner
of the file, root, or the owner of /tmp to remove a file in /tmp.

Maybe Minix needs a directory "sticky bit."

--
David F. SKoll