linux-kernel - Re: [PATCH] LSM: add static to security

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Date:	Fri, 19 Feb 2010 19:57:51 +0800
From:	wzt wzt <wzt.wzt@...il.com>
To:	Alexey Dobriyan <adobriyan@...il.com>
Cc:	linux-kernel@...r.kernel.org, sds@...ho.nsa.gov, jmorris@...ei.org,
	eparis@...isplace.org
Subject: Re: [PATCH] LSM: add static to security_ops variable

Maybe, but The attackers will use a complicated way to find the
security_ops address, it's a barrier to attackers. LSM is security
framework,  we don't want the attackers can easily to break it.  Just
like the sys_call_table variable in kernel 2.4.x(global and
writeable), evil drivers can extern the variable,  then replace the
Sys_X functions.

On Fri, Feb 19, 2010 at 7:44 PM, Alexey Dobriyan <adobriyan@...il.com> wrote:
> On Sun, Feb 7, 2010 at 1:24 PM, wzt wzt <wzt.wzt@...il.com> wrote:
>> security_ops was declared as a global variable, so other drivers or
>> kernel code can easily change its value, like:
>
> With your patch they still can.
>
>> extern struct security_operations *security_ops;
>> security_ops = NULL;
>>
>> then insmod this driver immediately, it will get an oops.  Other evil
>> drivers can aslo fake this variable as extern.
>
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