Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!ames!ucsd!sdcc6!sdcc19!sdcc15!pa1343
From: pa1343@sdcc15.ucsd.edu (pa1343)
Newsgroups: comp.os.minix
Subject: Re: MINIX1.2 rm-command
Keywords: MINIX1.2 (640K), rm-command fix
Message-ID: <1131@sdcc15.ucsd.edu>
Date: 17 Feb 89 18:21:09 GMT
References: <none> <1838@cps3xx.UUCP>
Reply-To: pa1343@sdcc15.UUCP ()
Organization: University of California, San Diego
Lines: 27

In article <1838@cps3xx.UUCP> rattan@frith.egr.msu.edu () writes:
>
>MINIX 1.2 (640K-PC) is being used to teach the OS course. It was
>observed that the 'rm' command is willing to remove any file in the
>system by switching over to interactive mode, when one is logged in as
>ast (not root or su).
>
>	$ rm /etc/passwd
>	rm: remove /etc/passwd (mode = 644) ?
Is rm setuid to root on your system?  If not then we have a BIG problem
because the unlink() system call is supposed to check for permissions.
rm should not be able to unlink a file not owned by the user.  That
decision is made by unlink().  Rm should also not be SUID root because
that will give it permissions to unlink any file.  Perhaps I ought to bring up 
my 1.3 version and see if this exists on the new version.  I will post any
strange results.

Oh, by the way, if a file is in a directory which is writable by you then
you can delete ANY regular file in that directory, regardless of its owner
or permissions.  This exists also on commercial UNIX. (sV, BSD)


-- 
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| John J. Marco -- pa1343@sdcc15.ucsd.edu | 
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