linux-kernel - Re: [PATCH v19 6/8] PM: hibernate: disable when there are active secretmem users

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Message-ID: <47d0e5b1-ffee-d694-4865-8718619c1be0@redhat.com>
Date:   Tue, 18 May 2021 12:27:13 +0200
From:   David Hildenbrand <david@...hat.com>
To:     Mark Rutland <mark.rutland@....com>,
        Mike Rapoport <rppt@...nel.org>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Alexander Viro <viro@...iv.linux.org.uk>,
        Andy Lutomirski <luto@...nel.org>,
        Arnd Bergmann <arnd@...db.de>, Borislav Petkov <bp@...en8.de>,
        Catalin Marinas <catalin.marinas@....com>,
        Christopher Lameter <cl@...ux.com>,
        Dan Williams <dan.j.williams@...el.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Elena Reshetova <elena.reshetova@...el.com>,
        "H. Peter Anvin" <hpa@...or.com>,
        Hagen Paul Pfeifer <hagen@...u.net>,
        Ingo Molnar <mingo@...hat.com>,
        James Bottomley <jejb@...ux.ibm.com>,
        Kees Cook <keescook@...omium.org>,
        "Kirill A. Shutemov" <kirill@...temov.name>,
        Matthew Wilcox <willy@...radead.org>,
        Matthew Garrett <mjg59@...f.ucam.org>,
        Michal Hocko <mhocko@...e.com>,
        Mike Rapoport <rppt@...ux.ibm.com>,
        Michael Kerrisk <mtk.manpages@...il.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Palmer Dabbelt <palmerdabbelt@...gle.com>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Peter Zijlstra <peterz@...radead.org>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Rick Edgecombe <rick.p.edgecombe@...el.com>,
        Roman Gushchin <guro@...com>,
        Shakeel Butt <shakeelb@...gle.com>,
        Shuah Khan <shuah@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Tycho Andersen <tycho@...ho.ws>, Will Deacon <will@...nel.org>,
        Yury Norov <yury.norov@...il.com>, linux-api@...r.kernel.org,
        linux-arch@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-fsdevel@...r.kernel.org, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, linux-kselftest@...r.kernel.org,
        linux-nvdimm@...ts.01.org, linux-riscv@...ts.infradead.org,
        x86@...nel.org
Subject: Re: [PATCH v19 6/8] PM: hibernate: disable when there are active
 secretmem users

On 18.05.21 12:24, Mark Rutland wrote:
> On Thu, May 13, 2021 at 09:47:32PM +0300, Mike Rapoport wrote:
>> From: Mike Rapoport <rppt@...ux.ibm.com>
>>
>> It is unsafe to allow saving of secretmem areas to the hibernation
>> snapshot as they would be visible after the resume and this essentially
>> will defeat the purpose of secret memory mappings.
>>
>> Prevent hibernation whenever there are active secret memory users.
> 
> Have we thought about how this is going to work in practice, e.g. on
> mobile systems? It seems to me that there are a variety of common
> applications which might want to use this which people don't expect to
> inhibit hibernate (e.g. authentication agents, web browsers).
> 
> Are we happy to say that any userspace application can incidentally
> inhibit hibernate?

It's worth noting that secretmem has to be explicitly enabled by the 
admin to even work.

-- 
Thanks,

David / dhildenb