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From: henry@utzoo.UUCP (Henry Spencer)
Newsgroups: net.unix-wizards
Subject: Re: magic numbers
Message-ID: <3616@utzoo.UUCP>
Date: Sat, 10-Mar-84 19:46:18 EST
Article-I.D.: utzoo.3616
Posted: Sat Mar 10 19:46:18 1984
Date-Received: Sat, 10-Mar-84 19:46:18 EST
References: <2639@alice.UUCP> opus.199, <1094@utah-gr.UUCP>
Organization: U of Toronto Zoology
Lines: 16

Yup, #! in the kernel permits setuid shell scripts.  I'm not sure
that this is a virtue, considering that people seem to be unaware of
the simply appalling number of security holes this opens up.  If you
think about the consequences of feeding a setuid shell file a non-
standard value of the IFS variable, with some suitably-named programs
lying around ready and waiting, you will have some idea of the sort
of things I'm referring to.  Shell files simply are not in a good
position to handle things like this; the interpretation process for
them is too complex and there is too little control over it.

This does not mean that I'm opposed to #! in the kernel, just that
setuid shell scripts seem a very weak justification for it, given
that they are grossly unsafe.
-- 
				Henry Spencer @ U of Toronto Zoology
				{allegra,ihnp4,linus,decvax}!utzoo!henry