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Date: Wed, 2 Oct 2013 15:13:16 +0200
Message-ID: <CABPqkBTdWZaJzv4PA3yBor+o_iaBSmK73CrUQeY1tANR36ah8Q@mail.gmail.com>
Subject: Re: [RFC] perf: mmap2 not covering VM_CLONE regions
From: Stephane Eranian <eranian@google.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>, LKML <linux-kernel@vger.kernel.org>,
        "mingo@elte.hu" <mingo@elte.hu>,
        "ak@linux.intel.com" <ak@linux.intel.com>,
        Arnaldo Carvalho de Melo <acme@redhat.com>,
        David Ahern <dsahern@gmail.com>, Jiri Olsa <jolsa@redhat.com>,
        Hugh Dickins <hughd@google.com>, Kees Cook <keescook@chromium.org>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Andrew Morton <akpm@linux-foundation.org>
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On Wed, Oct 2, 2013 at 3:01 PM, Peter Zijlstra <peterz@infradead.org> wrote:
> On Wed, Oct 02, 2013 at 02:59:32PM +0200, Stephane Eranian wrote:
>> On Wed, Oct 2, 2013 at 2:46 PM, Peter Zijlstra <peterz@infradead.org> wrote:
>> > On Wed, Oct 02, 2013 at 02:39:53PM +0200, Ingo Molnar wrote:
>> >>  - then there are timing attacks, and someone having access to a PMU
>> >>    context and who can trigger this SHA1 computation arbitrarily in task
>> >>    local context can run very accurate and low noise timing attacks...
>> >>
>> >>    I don't think the kernel's sha_transform() is hardened against timing
>> >>    attacks, it's performance optimized so it has variable execution time
>> >>    highly dependent on plaintext input - which leaks information about the
>> >>    plaintext.
>> >
>> > Typical user doesn't have enough priv to profile kernel space; once you
>> > do you also have enough priv to see kernel addresses outright (ie.
>> > kallsyms etc..).
>> >
>> I was going to say just that. But that's not the default, paranoid level
>> is at 1 by default and not 2. So I supposedly can still do:
>
> Oh right you are.. so yes that's a very viable avenue.

You mean simply encoding the vma->vm_mm as the ino number, for instance.
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