From: Luigi Semenzato <semenzato@google.com>
To: Johannes Weiner <hannes@cmpxchg.org>, Will Drewry <drewry@google.com>
Cc: Ric Mason <ric.masonn@gmail.com>,
linux-mm@kvack.org, Hugh Dickins <hughd@google.com>
Subject: Re: security: restricting access to swap
Date: Fri, 15 Mar 2013 10:27:23 -0700 [thread overview]
Message-ID: <CAA25o9SsVppWQ+Hi4LQ5OkiENHF5BQeNVD_G+a7CUbnPgOm=YQ@mail.gmail.com> (raw)
In-Reply-To: <20130315165509.GA1108@cmpxchg.org>
On Fri, Mar 15, 2013 at 9:55 AM, Johannes Weiner <hannes@cmpxchg.org> wrote:
> On Fri, Mar 15, 2013 at 08:48:49AM -0700, Luigi Semenzato wrote:
>> On Fri, Mar 15, 2013 at 2:04 AM, Ric Mason <ric.masonn@gmail.com> wrote:
>> > On 03/12/2013 07:57 AM, Luigi Semenzato wrote:
>> >>
>> >> Greetings linux-mmers,
>> >>
>> >> before we can fully deploy zram, we must ensure it conforms to the
>> >> Chrome OS security requirements. In particular, we do not want to
>> >> allow user space to read/write the swap device---not even root-owned
>> >> processes.
>> >
>> >
>> > Interesting.
>>
>> Thank you.
>>
>> >>
>> >> A similar restriction is available for /dev/mem under
>> >> CONFIG_STRICT_DEVMEM.
>> >
>> >
>> > Sorry, what's /dev/mem used for? and why relevant your topic?
>>
>> I don't know what it's used for Chrome OS, but I don't think it
>> matters. The point is that /dev/mem is compiled in the kernel, and
>> without CONFIG_STRICT_DEVMEM it offers a way for a root-owned process
>> to read/write all of physical memory. The situation is not as dire
>> with a swap device, but currently a root-owned process can open a
>> block device used for swap and peek and poke its data, which means
>> that a root-owned process has now potential access to the data segment
>> of any other process, among other things.
>
> How do you handle /proc/<pid>/mem?
Right. We do not. But... we might! We could turn it off and see if
it breaks anything important.
In any case, we don't like expanding the attack surface.
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next prev parent reply other threads:[~2013-03-15 17:27 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-03-11 23:57 Luigi Semenzato
2013-03-12 13:06 ` Konrad Rzeszutek Wilk
2013-03-12 15:46 ` Luigi Semenzato
2013-03-12 23:32 ` Simon Jeons
2013-03-15 9:04 ` Ric Mason
2013-03-15 15:48 ` Luigi Semenzato
2013-03-15 16:55 ` Johannes Weiner
2013-03-15 17:27 ` Luigi Semenzato [this message]
2013-03-15 22:19 ` Luigi Semenzato
2013-03-18 3:58 ` Hugh Dickins
2013-03-18 16:05 ` Luigi Semenzato
2013-03-18 23:43 ` KOSAKI Motohiro
2013-03-19 17:39 ` Will Drewry
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