linux-kernel - Re: [patch] remove MNT_NOEXEC check for PROT

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Message-ID: <20060925105355.GA4390@elf.ucw.cz>
Date:	Mon, 25 Sep 2006 12:53:55 +0200
From:	Pavel Machek <pavel@....cz>
To:	David Wagner <daw-usenet@...erner.cs.berkeley.edu>
Cc:	linux-kernel@...r.kernel.org
Subject: Re: [patch] remove MNT_NOEXEC check for PROT_EXEC mmaps

Hi!

> >> The consensus has been to add the same checks to mprotect.  They were
> >> not left out intentionally.
> >
> >But how about the anonymous mmap with PROT_EXEC set?
> 
> I'm curious about this, too.  ld-linux.so is a purely unprivileged
> program.  It isn't setuid root.  Can you write a variant of ld-linux.so
> that reads an executable into memory off of a partition mounted noexec and
> then begins executing that code?  (perhaps by using anonymous mmap
> with

Yes, you can, but to execute your ld-linux-ignore-noexec.so variant,
you need to put it somewhere with exec permissions, right?
								Pavel

-- 
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