From: David Hildenbrand <david@redhat.com>
To: Mike Rapoport <rppt@kernel.org>
Cc: linux-kernel@vger.kernel.org,
Alexey Dobriyan <adobriyan@gmail.com>,
Andrew Morton <akpm@linux-foundation.org>,
Andy Lutomirski <luto@kernel.org>, Arnd Bergmann <arnd@arndb.de>,
Borislav Petkov <bp@alien8.de>,
Dave Hansen <dave.hansen@linux.intel.com>,
James Bottomley <jejb@linux.ibm.com>,
Peter Zijlstra <peterz@infradead.org>,
Steven Rostedt <rostedt@goodmis.org>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
linux-api@vger.kernel.org, linux-mm@kvack.org, x86@kernel.org,
Mike Rapoport <rppt@linux.ibm.com>
Subject: Re: [PATCH RFC] mm: add MAP_EXCLUSIVE to create exclusive user mappings
Date: Wed, 30 Oct 2019 09:19:33 +0100 [thread overview]
Message-ID: <9eae3941-64cf-4ea1-0287-0e64bab192c6@redhat.com> (raw)
In-Reply-To: <20191030081529.GB20624@rapoport-lnx>
On 30.10.19 09:15, Mike Rapoport wrote:
> On Tue, Oct 29, 2019 at 12:02:34PM +0100, David Hildenbrand wrote:
>> On 27.10.19 11:17, Mike Rapoport wrote:
>>> From: Mike Rapoport <rppt@linux.ibm.com>
>>>
>>> The mappings created with MAP_EXCLUSIVE are visible only in the context of
>>> the owning process and can be used by applications to store secret
>>> information that will not be visible not only to other processes but to the
>>> kernel as well.
>>>
>>> The pages in these mappings are removed from the kernel direct map and
>>> marked with PG_user_exclusive flag. When the exclusive area is unmapped,
>>> the pages are mapped back into the direct map.
>>>
>>
>> Just a thought, the kernel is still able to indirectly read the contents of
>> these pages by doing a kdump from kexec environment, right?
>
> Right.
>
>> Also, I wonder
>> what would happen if you map such pages via /dev/mem into another user space
>> application and e.g., use them along with kvm [1].
>
> Do you mean that one application creates MAP_EXCLUSIVE and another
> applications accesses the same physical pages via /dev/mem?
Exactly.
>
> With /dev/mem all physical memory is visible...
Okay, so the statement "information that will not be visible not only to
other processes but to the kernel as well" is not correct. There are
easy ways to access that information if you really want to (might
require root permissions, though).
--
Thanks,
David / dhildenb
next prev parent reply other threads:[~2019-10-30 8:19 UTC|newest]
Thread overview: 60+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-27 10:17 [PATCH RFC] mm: add MAP_EXCLUSIVE to create exclusive user mappings Mike Rapoport
2019-10-27 10:17 ` Mike Rapoport
2019-10-28 12:31 ` Kirill A. Shutemov
2019-10-28 13:00 ` Mike Rapoport
2019-10-28 13:16 ` Kirill A. Shutemov
2019-10-28 13:55 ` Peter Zijlstra
2019-10-28 19:59 ` Edgecombe, Rick P
2019-10-28 21:00 ` Peter Zijlstra
2019-10-29 17:27 ` Edgecombe, Rick P
2019-10-30 10:04 ` Peter Zijlstra
2019-10-30 15:35 ` Alexei Starovoitov
2019-10-30 18:39 ` Peter Zijlstra
2019-10-30 18:52 ` Alexei Starovoitov
2019-10-30 17:48 ` Edgecombe, Rick P
2019-10-30 17:58 ` Dave Hansen
2019-10-30 18:01 ` Dave Hansen
2019-10-29 5:43 ` Dan Williams
2019-10-29 6:43 ` Kirill A. Shutemov
2019-10-29 8:56 ` Peter Zijlstra
2019-10-29 11:00 ` Kirill A. Shutemov
2019-10-29 12:39 ` AMD TLB errata, (Was: [PATCH RFC] mm: add MAP_EXCLUSIVE to create exclusive user mappings) Peter Zijlstra
2019-11-15 14:12 ` Tom Lendacky
2019-11-15 14:31 ` Peter Zijlstra
2019-10-29 19:43 ` [PATCH RFC] mm: add MAP_EXCLUSIVE to create exclusive user mappings Dan Williams
2019-10-29 20:07 ` Dave Hansen
2019-10-29 7:08 ` Christopher Lameter
2019-10-29 8:55 ` Mike Rapoport
2019-10-29 10:12 ` Christopher Lameter
2019-10-30 7:11 ` Mike Rapoport
2019-10-30 12:09 ` Christopher Lameter
2019-10-28 14:55 ` David Hildenbrand
2019-10-28 17:12 ` Dave Hansen
2019-10-28 17:32 ` Sean Christopherson
2019-10-28 18:08 ` Matthew Wilcox
2019-10-29 9:28 ` Mike Rapoport
2019-10-29 9:19 ` Mike Rapoport
2019-10-28 18:02 ` Andy Lutomirski
2019-10-29 11:02 ` David Hildenbrand
2019-10-30 8:15 ` Mike Rapoport
2019-10-30 8:19 ` David Hildenbrand [this message]
2019-10-31 19:16 ` Mike Rapoport
2019-10-31 21:52 ` Dan Williams
2019-10-27 10:30 ` Florian Weimer
2019-10-27 11:00 ` Mike Rapoport
2019-10-28 20:23 ` Florian Weimer
2019-10-29 9:01 ` Mike Rapoport
2019-10-28 20:44 ` Andy Lutomirski
2019-10-29 9:32 ` Mike Rapoport
2019-10-29 17:00 ` Andy Lutomirski
2019-10-30 8:40 ` Mike Rapoport
2019-10-30 21:28 ` Andy Lutomirski
2019-10-31 7:21 ` Mike Rapoport
2019-12-05 15:34 ` Mike Rapoport
2019-12-08 14:10 ` [PATCH] mm: extend memfd with ability to create secret memory kbuild test robot
2019-10-29 11:25 ` [PATCH RFC] mm: add MAP_EXCLUSIVE to create exclusive user mappings Reshetova, Elena
2019-10-29 15:13 ` Tycho Andersen
2019-10-29 17:03 ` Andy Lutomirski
2019-10-29 17:37 ` Alan Cox
2019-10-29 17:43 ` James Bottomley
2019-10-29 18:10 ` Andy Lutomirski
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