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From: Linus Torvalds <torvalds@linux-foundation.org>
To: Dominique Martinet <asmadeus@codewreck.org>
Cc: Andy Lutomirski <luto@amacapital.net>,
	Josh Snyder <joshs@netflix.com>,
	Dave Chinner <david@fromorbit.com>,
	Jiri Kosina <jikos@kernel.org>,
	Matthew Wilcox <willy@infradead.org>,
	Jann Horn <jannh@google.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Greg KH <gregkh@linuxfoundation.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Michal Hocko <mhocko@suse.com>, Linux-MM <linux-mm@kvack.org>,
	kernel list <linux-kernel@vger.kernel.org>,
	Linux API <linux-api@vger.kernel.org>
Subject: Re: [PATCH] mm/mincore: allow for making sys_mincore() privileged
Date: Wed, 16 Jan 2019 17:58:32 +1200	[thread overview]
Message-ID: <CAHk-=wjVjecbGRcxZUSwoSgAq9ZbMxbA=MOiqDrPgx7_P3xGhg@mail.gmail.com> (raw)
In-Reply-To: <20190116054613.GA11670@nautica>

On Wed, Jan 16, 2019 at 5:46 PM Dominique Martinet
<asmadeus@codewreck.org> wrote:
>
> "Being owner or has cap" (whichever cap) is probably OK.
> On the other hand, writeability check makes more sense in general -
> could we somehow check if the user has write access to the file instead
> of checking if it currently is opened read-write?

That's likely the best option. We could say "is it open for write, or
_could_ we open it for writing?"

It's a slightly annoying special case, and I'd have preferred to avoid
it, but it doesn't sound *compilcated*.

I'm on the road, but I did send out this:

    https://lore.kernel.org/lkml/CAHk-=wif_9nvNHJiyxHzJ80_WUb0P7CXNBvXkjZz-r1u0ozp7g@mail.gmail.com/

originally. The "let's try to only do the mmap residency" was the
optimistic "maybe we can just get rid of this complexity entirely"
version..

Anybody willing to test the above patch instead? And replace the

   || capable(CAP_SYS_ADMIN)

check with something like

   || inode_permission(inode, MAY_WRITE) == 0

instead?

(This is obviously after you've reverted the "only check mmap
residency" patch..)

            Linus

  reply	other threads:[~2019-01-16  5:58 UTC|newest]

Thread overview: 161+ 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 19:14 ` Vlastimil Babka
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 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 20:12   ` Jiri Kosina
2019-01-05 20:17     ` Linus Torvalds
2019-01-05 20:43       ` Jiri Kosina
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 19:56 ` kbuild test robot
2019-01-05 22:54 ` Jann Horn
2019-01-05 23:05   ` Linus Torvalds
2019-01-05 23:16     ` Linus Torvalds
2019-01-05 23:28       ` 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  1:50             ` Linus Torvalds
2019-01-06 21:46               ` Linus Torvalds
2019-01-08  4:43                 ` Dave Chinner
2019-01-08 17:57                   ` Linus Torvalds
2019-01-09  2:24                     ` Dave Chinner
2019-01-09  2:31                       ` Jiri Kosina
2019-01-09  4:39                         ` Dave Chinner
2019-01-09 10:08                           ` Jiri Kosina
2019-01-10  1:15                             ` Dave Chinner
2019-01-10  7:54                               ` Jiri Kosina
2019-01-09 18:25                           ` Linus Torvalds
2019-01-10  0:44                             ` Dave Chinner
2019-01-10  1:18                               ` Linus Torvalds
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
2019-01-11  1:47                                   ` Dave Chinner
2019-01-10  7:03                                 ` Dave Chinner
2019-01-10 11:47                                   ` Linus Torvalds
2019-01-10 12:24                                     ` Dominique Martinet
2019-01-10 22:11                                       ` Linus Torvalds
2019-01-11  2:03                                         ` Dave Chinner
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  7:36                                                 ` Dave Chinner
2019-01-11 16:26                                                   ` Linus Torvalds
2019-01-15 23:45                                                     ` Dave Chinner
2019-01-16  4:54                                                       ` 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  7:32                                             ` Dominique Martinet
2019-01-16  0:42                                         ` Josh Snyder
2019-01-16  5:00                                           ` Linus Torvalds
2019-01-16  5:25                                             ` Andy Lutomirski
2019-01-16  5:34                                               ` Linus Torvalds
2019-01-16  5:46                                                 ` Dominique Martinet
2019-01-16  5:58                                                   ` Linus Torvalds [this message]
2019-01-16  6:34                                                     ` Dominique Martinet
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 18:58                                                             ` Vlastimil Babka
2019-01-16 16:12                                                     ` Jiri Kosina
2019-01-16 17:48                                                       ` Linus Torvalds
2019-01-16 20:23                                                         ` Jiri Kosina
2019-01-16 21:37                                                           ` Matthew Wilcox
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
2019-01-18  4:54                                                               ` Linus Torvalds
2019-01-17  1:49                                                           ` Dominique Martinet
2019-01-23 20:27                                                           ` Linus Torvalds
2019-01-23 20:35                                                             ` Linus Torvalds
2019-01-23 23:12                                                               ` Jiri Kosina
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
2019-01-27 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
2019-01-17  2:22                                 ` Dave Chinner
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
2019-01-30 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
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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