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From: Daniel Gruss <daniel@gruss.cc>
To: Vlastimil Babka <vbabka@suse.cz>,
	Andrew Morton <akpm@linux-foundation.org>,
	Linus Torvalds <torvalds@linux-foundation.org>
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org,
	linux-api@vger.kernel.org, Peter Zijlstra <peterz@infradead.org>,
	Greg KH <gregkh@linuxfoundation.org>,
	Jann Horn <jannh@google.com>, Jiri Kosina <jkosina@suse.cz>,
	Dominique Martinet <asmadeus@codewreck.org>,
	Andy Lutomirski <luto@amacapital.net>,
	Dave Chinner <david@fromorbit.com>,
	Kevin Easton <kevin@guarana.org>,
	Matthew Wilcox <willy@infradead.org>,
	Cyril Hrubis <chrubis@suse.cz>, Tejun Heo <tj@kernel.org>,
	"Kirill A . Shutemov" <kirill@shutemov.name>,
	Jiri Kosina <jikos@kernel.org>
Subject: Re: [PATCH 2/3] mm/filemap: initiate readahead even if IOCB_NOWAIT is set for the I/O
Date: Thu, 31 Jan 2019 13:04:16 +0100	[thread overview]
Message-ID: <aea9a09a-9d01-fd08-d210-96b94162aba6@gruss.cc> (raw)
In-Reply-To: <20190130124420.1834-3-vbabka@suse.cz>

On 1/30/19 1:44 PM, Vlastimil Babka wrote:
> Close that sidechannel by always initiating readahead on the cache if we
> encounter a cache miss for preadv2(RWF_NOWAIT); with that in place, probing
> the pagecache residency itself will actually populate the cache, making the
> sidechannel useless.

I fear this does not really close the side channel. You can time the
preadv2 function and infer which path it took, so you just bring it down
to the same as using mmap and timing accesses.
If I understood it correctly, this patch just removes the advantages of
preadv2 over mmmap+access for the attacker.


Cheers,
Daniel


  parent reply	other threads:[~2019-01-31 12:04 UTC|newest]

Thread overview: 215+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-01-05 17:27 [PATCH] mm/mincore: allow for making sys_mincore() privileged Jiri Kosina
2019-01-05 17:27 ` Jiri Kosina
2019-01-05 19:14 ` Vlastimil Babka
2019-01-05 19:24   ` Jiri Kosina
2019-01-05 19:24     ` Jiri Kosina
2019-01-05 19:38     ` Vlastimil Babka
2019-01-08  9:14       ` Bernd Petrovitsch
2019-01-08 11:37         ` Jiri Kosina
2019-01-08 11:37           ` Jiri Kosina
2019-01-08 13:53           ` Bernd Petrovitsch
2019-01-08 14:08             ` Kirill A. Shutemov
2019-01-05 19:44 ` kbuild test robot
2019-01-05 19:46 ` Linus Torvalds
2019-01-05 19:46   ` Linus Torvalds
2019-01-05 20:12   ` Jiri Kosina
2019-01-05 20:12     ` Jiri Kosina
2019-01-05 20:17     ` Linus Torvalds
2019-01-05 20:17       ` Linus Torvalds
2019-01-05 20:43       ` Jiri Kosina
2019-01-05 20:43         ` Jiri Kosina
2019-01-05 21:54         ` Linus Torvalds
2019-01-05 21:54           ` Linus Torvalds
2019-01-06 11:33           ` Kevin Easton
2019-01-08  8:50           ` Kevin Easton
2019-01-18 14:23           ` Tejun Heo
2019-01-05 20:13   ` Linus Torvalds
2019-01-05 20:13     ` Linus Torvalds
2019-01-05 19:56 ` kbuild test robot
2019-01-05 22:54 ` Jann Horn
2019-01-05 22:54   ` Jann Horn
2019-01-05 23:05   ` Linus Torvalds
2019-01-05 23:05     ` Linus Torvalds
2019-01-05 23:16     ` Linus Torvalds
2019-01-05 23:16       ` Linus Torvalds
2019-01-05 23:28       ` Linus Torvalds
2019-01-05 23:28         ` Linus Torvalds
2019-01-05 23:39       ` Linus Torvalds
2019-01-05 23:39         ` Linus Torvalds
2019-01-06  0:11         ` Matthew Wilcox
2019-01-06  0:22           ` Linus Torvalds
2019-01-06  0:22             ` Linus Torvalds
2019-01-06  1:50             ` Linus Torvalds
2019-01-06  1:50               ` Linus Torvalds
2019-01-06 21:46               ` Linus Torvalds
2019-01-06 21:46                 ` Linus Torvalds
2019-01-08  4:43                 ` Dave Chinner
2019-01-08 17:57                   ` Linus Torvalds
2019-01-08 17:57                     ` Linus Torvalds
2019-01-09  2:24                     ` Dave Chinner
2019-01-09  2:31                       ` Jiri Kosina
2019-01-09  2:31                         ` Jiri Kosina
2019-01-09  4:39                         ` Dave Chinner
2019-01-09 10:08                           ` Jiri Kosina
2019-01-09 10:08                             ` Jiri Kosina
2019-01-10  1:15                             ` Dave Chinner
2019-01-10  7:54                               ` Jiri Kosina
2019-01-10  7:54                                 ` Jiri Kosina
2019-01-09 18:25                           ` Linus Torvalds
2019-01-09 18:25                             ` Linus Torvalds
2019-01-10  0:44                             ` Dave Chinner
2019-01-10  1:18                               ` Linus Torvalds
2019-01-10  1:18                                 ` Linus Torvalds
2019-01-10  5:26                                 ` Andy Lutomirski
2019-01-10  5:26                                   ` Andy Lutomirski
2019-01-10 14:47                                   ` Matthew Wilcox
2019-01-10 21:44                                     ` Dave Chinner
2019-01-10 21:59                                       ` Linus Torvalds
2019-01-10 21:59                                         ` Linus Torvalds
2019-01-11  1:47                                   ` Dave Chinner
2019-01-10  7:03                                 ` Dave Chinner
2019-01-10 11:47                                   ` Linus Torvalds
2019-01-10 11:47                                     ` Linus Torvalds
2019-01-10 12:24                                     ` Dominique Martinet
2019-01-10 12:24                                       ` Dominique Martinet
2019-01-10 22:11                                       ` Linus Torvalds
2019-01-10 22:11                                         ` Linus Torvalds
2019-01-11  2:03                                         ` Dave Chinner
2019-01-11  2:18                                           ` Linus Torvalds
2019-01-11  2:18                                             ` Linus Torvalds
2019-01-11  4:04                                             ` Dave Chinner
2019-01-11  4:08                                               ` Andy Lutomirski
2019-01-11  7:20                                                 ` Dave Chinner
2019-01-11  7:08                                               ` Linus Torvalds
2019-01-11  7:08                                                 ` Linus Torvalds
2019-01-11  7:36                                                 ` Dave Chinner
2019-01-11 16:26                                                   ` Linus Torvalds
2019-01-11 16:26                                                     ` Linus Torvalds
2019-01-15 23:45                                                     ` Dave Chinner
2019-01-16  4:54                                                       ` Linus Torvalds
2019-01-16  4:54                                                         ` Linus Torvalds
2019-01-16  5:49                                                         ` Linus Torvalds
2019-01-16  5:49                                                           ` Linus Torvalds
2019-01-17  1:26                                                         ` Dave Chinner
2019-02-20 15:49                                                     ` Nicolai Stange
2019-01-11  4:57                                         ` Dominique Martinet
2019-01-11  7:11                                           ` Linus Torvalds
2019-01-11  7:11                                             ` Linus Torvalds
2019-01-11  7:32                                             ` Dominique Martinet
2019-01-16  0:42                                         ` Josh Snyder
2019-01-16  5:00                                           ` Linus Torvalds
2019-01-16  5:00                                             ` Linus Torvalds
2019-01-16  5:25                                             ` Andy Lutomirski
2019-01-16  5:34                                               ` Linus Torvalds
2019-01-16  5:34                                                 ` Linus Torvalds
2019-01-16  5:46                                                 ` Dominique Martinet
2019-01-16  5:58                                                   ` Linus Torvalds
2019-01-16  5:58                                                     ` Linus Torvalds
2019-01-16  6:34                                                     ` Dominique Martinet
2019-01-16  7:52                                                       ` Josh Snyder
2019-01-16  7:52                                                         ` Josh Snyder
2019-01-16 12:18                                                         ` Kevin Easton
2019-01-17 21:45                                                         ` Vlastimil Babka
2019-01-18  4:49                                                           ` Linus Torvalds
2019-01-18  4:49                                                             ` Linus Torvalds
2019-01-18 18:58                                                             ` Vlastimil Babka
2019-01-16 16:12                                                     ` Jiri Kosina
2019-01-16 16:12                                                       ` Jiri Kosina
2019-01-16 17:48                                                       ` Linus Torvalds
2019-01-16 17:48                                                         ` Linus Torvalds
2019-01-16 20:23                                                         ` Jiri Kosina
2019-01-16 20:23                                                           ` Jiri Kosina
2019-01-16 21:37                                                           ` Matthew Wilcox
2019-01-16 21:41                                                             ` Jiri Kosina
2019-01-16 21:41                                                               ` Jiri Kosina
2019-01-17  9:52                                                               ` Cyril Hrubis
2019-01-28 13:49                                                               ` Cyril Hrubis
2019-01-17  4:51                                                             ` Linus Torvalds
2019-01-17  4:51                                                               ` Linus Torvalds
2019-01-18  4:54                                                               ` Linus Torvalds
2019-01-18  4:54                                                                 ` Linus Torvalds
2019-01-17  1:49                                                           ` Dominique Martinet
2019-01-23 20:27                                                           ` Linus Torvalds
2019-01-23 20:27                                                             ` Linus Torvalds
2019-01-23 20:35                                                             ` Linus Torvalds
2019-01-23 20:35                                                               ` Linus Torvalds
2019-01-23 23:12                                                               ` Jiri Kosina
2019-01-23 23:12                                                                 ` Jiri Kosina
2019-01-24  0:20                                                                 ` Linus Torvalds
2019-01-24  0:20                                                                   ` Linus Torvalds
2019-01-24  0:24                                                             ` Dominique Martinet
2019-01-24 12:45                                                               ` Dominique Martinet
2019-01-24 14:25                                                                 ` Jiri Kosina
2019-01-24 14:25                                                                   ` Jiri Kosina
2019-01-27 22:35                                                                   ` Jiri Kosina
2019-01-27 22:35                                                                     ` Jiri Kosina
2019-01-28  0:05                                                                     ` Dominique Martinet
2019-01-29 23:52                                                                       ` Jiri Kosina
2019-01-30  9:09                                                                         ` Michal Hocko
2019-01-30 12:29                                                                           ` Jiri Kosina
2019-01-16 12:36                                             ` Matthew Wilcox
2019-01-10 14:50                               ` Matthew Wilcox
2019-01-11  7:36                               ` Jiri Kosina
2019-01-11  7:36                                 ` Jiri Kosina
2019-01-17  2:22                                 ` Dave Chinner
2019-01-17  8:18                                   ` Jiri Kosina
2019-01-17  8:18                                     ` Jiri Kosina
2019-01-17 21:06                                     ` Dave Chinner
2019-01-07  4:32             ` Dominique Martinet
2019-01-07 10:33               ` Vlastimil Babka
2019-01-07 11:08                 ` Dominique Martinet
2019-01-07 11:59                   ` Vlastimil Babka
2019-01-07 13:29                   ` Daniel Gruss
2019-01-07 10:10         ` Michael Ellerman
2019-01-05 23:09   ` Jiri Kosina
2019-01-05 23:09     ` Jiri Kosina
2019-01-30 12:44 ` [PATCH 0/3] mincore() and IOCB_NOWAIT adjustments Vlastimil Babka
2019-01-30 12:44   ` [PATCH 1/3] mm/mincore: make mincore() more conservative Vlastimil Babka
2019-01-31  9:43     ` Michal Hocko
2019-01-31  9:51       ` Dominique Martinet
2019-01-31 17:46       ` Josh Snyder
2019-02-01  8:56     ` Vlastimil Babka
2019-03-06 23:13     ` Andrew Morton
2019-03-07  0:01       ` Jiri Kosina
2019-03-07  0:40         ` Dominique Martinet
2019-03-07  5:46           ` Jiri Kosina
2019-01-30 12:44   ` [PATCH 2/3] mm/filemap: initiate readahead even if IOCB_NOWAIT is set for the I/O Vlastimil Babka
2019-01-30 15:04     ` Florian Weimer
2019-01-30 15:15       ` Jiri Kosina
2019-01-31 10:47         ` Florian Weimer
2019-01-31 11:34           ` Jiri Kosina
2019-01-31  9:56     ` Michal Hocko
2019-01-31 10:15       ` Jiri Kosina
2019-01-31 10:23         ` Michal Hocko
2019-01-31 10:30           ` Jiri Kosina
2019-01-31 11:32             ` Michal Hocko
2019-01-31 17:54           ` Linus Torvalds
2019-02-01  5:13             ` Dave Chinner
2019-02-01  7:05               ` Linus Torvalds
2019-02-01  7:21                 ` Linus Torvalds
2019-02-01  1:44       ` Dave Chinner
2019-02-12 15:48         ` Jiri Kosina
2019-01-31 12:04     ` Daniel Gruss [this message]
2019-01-31 12:06       ` Vlastimil Babka
2019-01-31 12:08       ` Jiri Kosina
2019-01-31 12:57         ` Daniel Gruss
2019-01-30 12:44   ` [PATCH 3/3] mm/mincore: provide mapped status when cached status is not allowed Vlastimil Babka
2019-01-31 10:09     ` Michal Hocko
2019-02-01  9:04       ` Vlastimil Babka
2019-02-01  9:11         ` Michal Hocko
2019-02-01  9:27           ` Vlastimil Babka
2019-02-06 20:14             ` Jiri Kosina
2019-02-12  3:44         ` Jiri Kosina
2019-02-12  6:36           ` Michal Hocko
2019-02-12 13:09             ` Jiri Kosina
2019-02-12 14:01               ` Michal Hocko
2019-03-06 12:11   ` [PATCH 0/3] mincore() and IOCB_NOWAIT adjustments Jiri Kosina
2019-03-06 22:35     ` Andrew Morton
2019-03-06 22:48       ` Jiri Kosina
2019-03-06 23:23         ` Andrew Morton
2019-03-06 23:32           ` Dominique Martinet
2019-03-06 23:38             ` Andrew Morton
2019-03-09 16:53               ` Linus Torvalds
2019-03-12 14:17   ` [PATCH v2 0/2] prevent mincore() page cache leaks Vlastimil Babka
2019-03-12 14:17     ` [PATCH v2 1/2] mm/mincore: make mincore() more conservative Vlastimil Babka
2019-03-12 14:17     ` [PATCH v2 2/2] mm/mincore: provide mapped status when cached status is not allowed Vlastimil Babka

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