From: Al Viro <viro@ftp.linux.org.uk>
To: Alon Bar-Lev <alon.barlev@gmail.com>
Cc: Brian Gerst <bgerst@didntduck.org>,
"Jonathan M. McCune" <jonmccune@cmu.edu>,
linux-kernel@vger.kernel.org,
Arvind Seshadri <arvinds@cs.cmu.edu>, Bryan Parno <parno@cmu.edu>
Subject: Re: using segmentation in the kernel
Date: Tue, 11 Oct 2005 22:12:15 +0100 [thread overview]
Message-ID: <20051011211215.GV7992@ftp.linux.org.uk> (raw)
In-Reply-To: <434C1F8E.6080405@gmail.com>
On Tue, Oct 11, 2005 at 10:24:46PM +0200, Alon Bar-Lev wrote:
> Brian Gerst wrote:
> >Jonathan M. McCune wrote:
> >
> >>Hello,
> >>
> >Why send the kernel back to the 2.0 days? There is no valid reason for
> >doing this with they way x86 segmentation works, which is why it was
> >done away with in 2.1.
> >
>
> But with segmentation you can set code to be read-only,
> disallow execution from stack, separate modules so that they
> will not affect kernel and more...
You do realize that it's a BS, don't you?
* attacker that would rewrite kernel code can switch a pointer to method in
any of the method tables (or pointer to the entire method table, while we are
at it).
* overwriting return address is trivial if you got stack smashing and there
is a plenty of interesting functions in the kernel ready to elevate priveleges
* modules rely on practically complete access to kernel data structures, so
no amount of playing with rings will change anything for them.
next prev parent reply other threads:[~2005-10-11 21:12 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-10-11 20:15 using segmentation in the kernel Jonathan M. McCune
2005-10-11 20:36 ` Brian Gerst
2005-10-11 20:24 ` Alon Bar-Lev
2005-10-11 21:12 ` Al Viro [this message]
2005-10-11 21:14 ` Brian Gerst
2005-10-12 9:05 ` Arjan van de Ven
2005-10-12 16:07 ` Alan Cox
2005-10-12 15:44 ` Arjan van de Ven
2005-10-12 23:55 ` Jonathan M. McCune
2005-10-12 13:03 ` linux-os (Dick Johnson)
2005-10-13 8:51 ` Denis Vlasenko
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