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Path: utzoo!mnetor!seismo!husc6!ddl
From: ddl@husc6.HARVARD.EDU (Dan Lanciani)
Newsgroups: net.bugs.4bsd
Subject: Re: tip shell escape (4.3BSD)
Message-ID: <191@husc6.HARVARD.EDU>
Date: Thu, 21-Aug-86 21:51:24 EDT
Article-I.D.: husc6.191
Posted: Thu Aug 21 21:51:24 1986
Date-Received: Fri, 22-Aug-86 05:38:16 EDT
References: <600@varian.UUCP>
Distribution: net
Organization: Harvard University, Cambridge Mass
Lines: 17
Summary: silly security feature...

In article <600@varian.UUCP>, david@varian.UUCP (David Brown) writes:
> I've been having problems using tip on 4.3BSD.  When I try to use any
> tilde command that requires forking a shell (~!, ~$, etc.), I get:
> 
> 	/bin/csh: permission denied
> 
	This is a "feature" of the C-shell.  If on interactive startup
it finds that its real uid != its effective uid or its real gid !=
its effective gid it prints this unhelpful message and exits.  I assume
this is supposed to prevent evil hackers from getting privileged shells.
Of course, all evil hackers use sh so nothing is gained by the hack.
It would make much more sense to fix the program (tip in this case) than
to break the shell.  Note that this also makes setuid C-shell scripts
fail.

					Dan Lanciani
					ddl@harvard.*