linux-kernel - Re: [PATCH v7 7/7] mm/madvise: allow KSM hints for remote API

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <CAG48ez1WfUN2eZyiQL0thsO3cYW6TgC-NzEj=gP2KfkJ7BdK=Q@mail.gmail.com>
Date:   Thu, 11 Jun 2020 04:21:27 +0200
From:   Jann Horn <jannh@...gle.com>
To:     Oleksandr Natalenko <oleksandr@...hat.com>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        LKML <linux-kernel@...r.kernel.org>,
        linux-mm <linux-mm@...ck.org>,
        Linux API <linux-api@...r.kernel.org>,
        Suren Baghdasaryan <surenb@...gle.com>,
        Tim Murray <timmurray@...gle.com>,
        Daniel Colascione <dancol@...gle.com>,
        Sandeep Patil <sspatil@...gle.com>,
        Sonny Rao <sonnyrao@...gle.com>,
        Brian Geffon <bgeffon@...gle.com>,
        Michal Hocko <mhocko@...e.com>,
        Johannes Weiner <hannes@...xchg.org>,
        Shakeel Butt <shakeelb@...gle.com>,
        John Dias <joaodias@...gle.com>,
        Joel Fernandes <joel@...lfernandes.org>,
        Alexander Duyck <alexander.h.duyck@...ux.intel.com>,
        sj38.park@...il.com, Minchan Kim <minchan@...nel.org>,
        SeongJae Park <sjpark@...zon.de>
Subject: Re: [PATCH v7 7/7] mm/madvise: allow KSM hints for remote API

On Mon, Mar 2, 2020 at 8:36 PM Minchan Kim <minchan@...nel.org> wrote:
> From: Oleksandr Natalenko <oleksandr@...hat.com>
>
> It all began with the fact that KSM works only on memory that is marked
> by madvise(). And the only way to get around that is to either:
[...]
> To overcome this restriction, lets employ a new remote madvise API. This
> can be used by some small userspace helper daemon that will do auto-KSM
> job for us.
>
> I think of two major consumers of remote KSM hints:
[...]
>   * heavy applications, that can be run in multiple instances, not
>     limited to opensource ones like Firefox, but also those that cannot be
>     modified since they are binary-only and, maybe, statically linked.

Just as a note, since you're mentioning Firefox as a usecase: Memory
deduplication between browser renderers creates new side channels and
is a questionable idea from a security standpoint. Memory
deduplication is (mostly) fine if either all involved processes are
trusted or no involved processes contain secrets, but browsers usually
run tons of untrusted code while at the same time containing lots of
valuable secrets.