Path: utzoo!attcan!uunet!yale!cmcl2!phri!roy
From: roy@phri.UUCP (Roy Smith)
Newsgroups: comp.unix.wizards
Subject: Re: Nasty Security Hole?
Keywords: mail permissions security
Message-ID: <3608@phri.UUCP>
Date: 19 Nov 88 23:53:40 GMT
References: <175@ernie.NECAM.COM> <189@wyn386.UUCP>
Reply-To: roy@phri.UUCP (Roy Smith)
Distribution: na
Organization: Public Health Research Inst. (NY, NY)
Lines: 21

mikef@wyn386.UUCP (Mike Faber) writes:
> Why can a person with read permission only be able to remove the file?

	I'm not sure I understand what Mike is getting at, but it sounds
like he has a directory which is world-writable with a read-only file in
it.  If this is the situation, then yes, people can remove the read-only
file.  This is rather counter-intuitive, but a straight-forward result of
the file system semantics.  All Mike need do is make sure that the
directory in which his file resides is not world-writable and he should be
OK.

	Berkeley systems (and maybe others?) have a "sticky directory"
feature which allows people to create files in publicly writeable
directories (i.e. /tmp) without letting other people remove or rename them.
At least on my system (MtXinue 4.3BSD/NFS) I havn't gotten stickey
directories to work properly; possibly I'm just doing something wrong?
-- 
Roy Smith, System Administrator
Public Health Research Institute
{allegra,philabs,cmcl2,rutgers}!phri!roy -or- phri!roy@uunet.uu.net
"The connector is the network"