Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Subject: Re: [kernel-hardening] [PATCH 4/6] Protectable Memory
To:     Kees Cook <keescook@chromium.org>,
        Igor Stoppa <igor.stoppa@huawei.com>
Cc:     Boris Lukashev <blukashev@sempervictus.com>,
        Christopher Lameter <cl@linux.com>,
        Matthew Wilcox <willy@infradead.org>,
        Jann Horn <jannh@google.com>,
        Jerome Glisse <jglisse@redhat.com>,
        Michal Hocko <mhocko@kernel.org>,
        Christoph Hellwig <hch@infradead.org>,
        linux-security-module <linux-security-module@vger.kernel.org>,
        Linux-MM <linux-mm@kvack.org>,
        kernel list <linux-kernel@vger.kernel.org>,
        Kernel Hardening <kernel-hardening@lists.openwall.com>
References: <20180124175631.22925-1-igor.stoppa@huawei.com>
 <20180124175631.22925-5-igor.stoppa@huawei.com>
 <CAG48ez0JRU8Nmn7jLBVoy6SMMrcj46R0_R30Lcyouc4R9igi-g@mail.gmail.com>
 <20180126053542.GA30189@bombadil.infradead.org>
 <alpine.DEB.2.20.1802021236510.31548@nuc-kabylake>
 <f2ddaed0-313e-8664-8a26-9d10b66ed0c5@huawei.com>
 <b75b5903-0177-8ad9-5c2b-fc63438fb5f2@huawei.com>
 <CAFUG7CfrCpcbwgf5ixMC5EZZgiVVVp1NXhDHK1UoJJcC08R2qQ@mail.gmail.com>
 <8818bfd4-dd9f-f279-0432-69b59531bd41@huawei.com>
 <CAFUG7CeUhFcvA82uZ2ZH1j_6PM=aBo4XmYDN85pf8G0gPU44dg@mail.gmail.com>
 <17e5b515-84c8-dca2-1695-cdf819834ea2@huawei.com>
 <CAGXu5j+LS1pgOOroi7Yxp2nh=DwtTnU3p-NZa6bQu_wkvvVkwg@mail.gmail.com>
From:   Laura Abbott <labbott@redhat.com>
Message-ID: <414027d3-dd73-cf11-dc2a-e8c124591646@redhat.com>
Date:   Mon, 12 Feb 2018 16:40:40 -0800
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101
 Thunderbird/52.5.2
MIME-Version: 1.0
In-Reply-To: <CAGXu5j+LS1pgOOroi7Yxp2nh=DwtTnU3p-NZa6bQu_wkvvVkwg@mail.gmail.com>
Content-Type: text/plain; charset=utf-8; format=flowed
Content-Language: en-US
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On 02/12/2018 03:27 PM, Kees Cook wrote:
> On Sun, Feb 4, 2018 at 7:05 AM, Igor Stoppa <igor.stoppa@huawei.com> wrote:
>> On 04/02/18 00:29, Boris Lukashev wrote:
>>> On Sat, Feb 3, 2018 at 3:32 PM, Igor Stoppa <igor.stoppa@huawei.com> wrote:
>>
>> [...]
>>
>>>> What you are suggesting, if I have understood it correctly, is that,
>>>> when the pool is protected, the addresses already given out, will become
>>>> traps that get resolved through a lookup table that is built based on
>>>> the content of each allocation.
>>>>
>>>> That seems to generate a lot of overhead, not to mention the fact that
>>>> it might not play very well with the MMU.
>>>
>>> That is effectively what i'm suggesting - as a form of protection for
>>> consumers against direct reads of data which may have been corrupted
>>> by some irrelevant means. In the context of pmalloc, it would probably
>>> be a separate type of ro+verified pool
>> ok, that seems more like an extension though.
>>
>> ATM I am having problems gaining traction to get even the basic merged :-)
>>
>> I would consider this as a possibility for future work, unless it is
>> said that it's necessary for pmalloc to be accepted ...
> 
> I would agree: let's get basic functionality in first. Both
> verification and the physmap part can be done separately, IMO.

Skipping over physmap leaves a pretty big area of exposure that could
be difficult to solve later. I appreciate this might block basic
functionality but I don't think we should just gloss over it without
at least some idea of what we would do.

Thanks,
Laura