linux-kernel - Re: O_NOLINK for open()

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Message-ID: <Pine.LNX.4.58.0709141923001.2235@be1.lrz>
Date:	Fri, 14 Sep 2007 19:26:30 +0200 (CEST)
From:	Bodo Eggert <7eggert@....de>
To:	Andreas Schwab <schwab@...e.de>
cc:	7eggert@....de, Brent Casavant <bcasavan@....com>,
	Gabor Gombas <gombasg@...aki.hu>, linux-kernel@...r.kernel.org
Subject: Re: O_NOLINK for open()

On Fri, 14 Sep 2007, Andreas Schwab wrote:
> Bodo Eggert <7eggert@....de> writes:

> > ~/tmp > cp /bin/sleep .
> > ~/tmp > chmod u+s sleep
> > ~/tmp > ./sleep 2147483647 &
> > [1] 2823
> > ~/tmp > strace -p 2823
> > Process 2823 attached - interrupt to quit
> > setup(
> 
> You didn't change the owner, so this is not a setuid execution.

I expected that, but I wanted to be sure before telling bull****.
Besides that, if the suid program was owned by the suid-to user,
that user could modify the binary in order to prepare a future attack.
-- 
Top 100 things you don't want the sysadmin to say:
16. find /usr2 -name nethack -exec rm -f {};
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