To: linux-kernel@vger.kernel.org
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From: daw@cs.berkeley.edu (David Wagner)
Newsgroups: isaac.lists.linux-kernel
Subject: Re: [patch] remove MNT_NOEXEC check for PROT_EXEC mmaps
Date: Mon, 25 Sep 2006 20:12:06 +0000 (UTC)
Organization: University of California, Berkeley
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Reply-To: daw-usenet@taverner.cs.berkeley.edu (David Wagner)
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Originator: daw@taverner.cs.berkeley.edu (David Wagner)
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Arjan van de Ven  wrote:
>[...]  so you remove a security check ... [...]
>
>If you can mmap PROT_EXEC the "noexec" mount option doesn't mean
>anything! Because a elf binary loader is easily written in
>perl/shell/whatever, the kernel "x" bit is just a convenience there!
>The PROT_EXEC check at least makes it a bit harder to do anything like
>this; not impossible obviously

The last sentence of your post implies that this never was a security
check.  (I'll believe it was a check to prevent some kinds of accidental
misbehavior, but I don't believe it prevents deliberate misbehavior.)
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