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From: bzs@bu-cs.bu.EDU (Barry Shein)
Newsgroups: comp.unix.wizards
Subject: Free Software Foundation (was: Re: Mach, the new standard?)
Message-ID: <9615@brl-adm.ARPA>
Date: Sun, 4-Oct-87 15:04:47 EDT
Article-I.D.: brl-adm.9615
Posted: Sun Oct  4 15:04:47 1987
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From: der Mouse <mouse@mcgill-vision.uucp>
>I could live without file protections.  (I already do.  My login has
>uid 0.)

Remember, there's more danger to this sort of approach than simply
security and file access. For example I remember that in 4.2 the
statement (perhaps everywhere else, I haven't tried it):

	if [ -x foo ]

in a shell script would always return true for any file if you were
root for some obscure reason. I had written a simple shell script for
the students called 'setpriv' which took either 'public' or 'private'
and a list of files and did something reasonable with the permission
bits. It had to propagate the execute bit and I noticed it behaved
strangely under the root acct, this was the cause.

I'm sure there are other gotchas lurking, I guess if asked to find
some I would at things like mail locks and exclusive access bits that
have nothing to do with security per se (in the sense of unauthorized
access to data) but more to do with preventing accidents like race
conditions.

It can be very subtly introduced into a piece of software, such as in
my example.

	-Barry Shein, Boston University