linux-kernel - Re: [PATCH] Check files' signatures before doing suid/sgid [2/4]

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Message-ID: <20070625105435.GD24777@faui01.informatik.uni-erlangen.de>
Date:	Mon, 25 Jun 2007 12:54:35 +0200
From:	Johannes Schlumberger <spjsschl@...d.informatik.uni-erlangen.de>
To:	Jan Engelhardt <jengelh@...putergmbh.de>
Cc:	Alexander Wuerstlein <snalwuer@....informatik.uni-erlangen.de>,
	Arjan van de Ven <arjan@...radead.org>,
	linux-kernel@...r.kernel.org, arw@....name
Subject: Re: [PATCH] Check files' signatures before doing suid/sgid [2/4]


Hi,

> >If a process uses read() it needs some executable and writable memory. We do
> >check for this in mprotect(). There is a problem with the i386-architecture,
> >because it allows execution of any readable page (except with newer
> >processors). But beyond that ugliness of i386, it should not be possible to
> >execute anything without us noticing it (hopefully).
>
> r and x together is not a problem IMHO.

It is, if you would want to have rw but can only get rwx.
regards,
	Johannes

-- 
Johannes Schlumberger                      Department of Computer Science IV
Martensstrasse 1  D-91058 Erlangen Germany  University of Erlangen-Nuremberg
             http://wwwcip.informatik.uni-erlangen.de/~spjsschl
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