linux-kernel - Re: [PATCH v2 1/3] module: verify address is read-only

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Message-ID: <CAGXu5jKMqPFktwOk_iodie=2J+sT2pHBbTzeuKfDMEYq=dE8Ww@mail.gmail.com>
Date:   Tue, 21 Feb 2017 12:32:16 -0800
From:   Kees Cook <keescook@...omium.org>
To:     Stephen Hemminger <stephen@...workplumber.org>
Cc:     Eddie Kovsky <ewk@...ovsky.org>, Jessica Yu <jeyu@...hat.com>,
        Rusty Russell <rusty@...tcorp.com.au>,
        KY Srinivasan <kys@...rosoft.com>,
        Haiyang Zhang <haiyangz@...rosoft.com>,
        Stephen Hemminger <sthemmin@...rosoft.com>,
        LKML <linux-kernel@...r.kernel.org>,
        "kernel-hardening@...ts.openwall.com" 
        <kernel-hardening@...ts.openwall.com>
Subject: Re: [PATCH v2 1/3] module: verify address is read-only

On Mon, Feb 20, 2017 at 9:14 AM, Stephen Hemminger
<stephen@...workplumber.org> wrote:
> On Fri, 17 Feb 2017 21:58:42 -0800
> "Eddie Kovsky" <ewk@...ovsky.org> wrote:
>
>> Implement a mechanism to check if a module's address is in
>> the rodata or ro_after_init sections. It mimics the exsiting functions
>> that test if an address is inside a module's text section.
>>
>> Signed-off-by: Eddie Kovsky <ewk@...ovsky.org>
>
> I don't see the point of this for many of the hyper-v functions.
> They are only called from a small number of places, and this can be validated
> by code inspection. Adding this seems just seems to be code bloat to me.

I think it has value in that it effectively blocks any way for
non-ro_after_init structures from being passed into these functions.
Since there are so few callers now, it's the perfect place to add
this.

-Kees

-- 
Kees Cook
Pixel Security