From: Brian Gerst <bgerst@didntduck.org>
To: Alon Bar-Lev <alon.barlev@gmail.com>
Cc: "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 17:14:50 -0400 [thread overview]
Message-ID: <434C2B4A.7040309@didntduck.org> (raw)
In-Reply-To: <434C1F8E.6080405@gmail.com>
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...
>
> The main problem with segmentation is that it is x86 specific...
Too much pain for for not enough gain. Segments are not fine-grained
enough to work well. Look at the PaX and execshield hacks for
userspace. You are far better off working at the page-table level (RO
and NX pages) which has the advantage of being portable.
--
Brian Gerst
next prev parent reply other threads:[~2005-10-11 21:15 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
2005-10-11 21:14 ` Brian Gerst [this message]
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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