From: David Herrmann <dh.herrmann@gmail.com>
To: linux-kernel <linux-kernel@vger.kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Hugh Dickins <hughd@google.com>,
Linus Torvalds <torvalds@linux-foundation.org>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>,
Ryan Lortie <desrt@desrt.ca>, linux-mm <linux-mm@kvack.org>,
linux-fsdevel <linux-fsdevel@vger.kernel.org>,
Linux API <linux-api@vger.kernel.org>,
Greg Kroah-Hartman <greg@kroah.com>,
John Stultz <john.stultz@linaro.org>,
Lennart Poettering <lennart@poettering.net>,
Daniel Mack <zonque@gmail.com>, Kay Sievers <kay@vrfy.org>,
Tony Battersby <tonyb@cybernetics.com>,
Andy Lutomirski <luto@amacapital.net>,
David Herrmann <dh.herrmann@gmail.com>
Subject: Re: [PATCH v3 0/7] File Sealing & memfd_create()
Date: Tue, 8 Jul 2014 18:54:56 +0200 [thread overview]
Message-ID: <CANq1E4QZ95RmJ7i=6TzEP4e+WREzKtXmmjjDrvz4BgAhVHoeuQ@mail.gmail.com> (raw)
In-Reply-To: <1402655819-14325-1-git-send-email-dh.herrmann@gmail.com>
Hi
On Fri, Jun 13, 2014 at 12:36 PM, David Herrmann <dh.herrmann@gmail.com> wrote:
> Hi
>
> This is v3 of the File-Sealing and memfd_create() patches. You can find v1 with
> a longer introduction at gmane:
> http://thread.gmane.org/gmane.comp.video.dri.devel/102241
> An LWN article about memfd+sealing is available, too:
> https://lwn.net/Articles/593918/
> v2 with some more discussions can be found here:
> http://thread.gmane.org/gmane.linux.kernel.mm/115713
>
> This series introduces two new APIs:
> memfd_create(): Think of this syscall as malloc() but it returns a
> file-descriptor instead of a pointer. That file-descriptor is
> backed by anon-memory and can be memory-mapped for access.
> sealing: The sealing API can be used to prevent a specific set of operations
> on a file-descriptor. You 'seal' the file and give thus the
> guarantee, that it cannot be modified in the specific ways.
>
> A short high-level introduction is also available here:
> http://dvdhrm.wordpress.com/2014/06/10/memfd_create2/
>
>
> Changed in v3:
> - fcntl() now returns EINVAL if the FD does not support sealing. We used to
> return EBADF like pipe_fcntl() does, but that is really weird and I don't
> like repeating that.
> - seals are now saved as "unsigned int" instead of "u32".
> - i_mmap_writable is now an atomic so we can deny writable mappings just like
> i_writecount does.
> - SHMEM_ALLOW_SEALING is dropped. We initialize all objects with F_SEAL_SEAL
> and only unset it for memfds that shall support sealing.
> - memfd_create() no longer has a size argument. It was redundant, use
> ftruncate() or fallocate().
> - memfd_create() flags are "unsigned int" now, instead of "u64".
> - NAME_MAX off-by-one fix
> - several cosmetic changes
> - Added AIO/Direct-IO page-pinning protection
>
> The last point is the most important change in this version: We now bail out if
> any page-refcount is elevated while setting SEAL_WRITE. This prevents parallel
> GUP users from writing to sealed files _after_ they were sealed. There is also a
> new FUSE-based test-case to trigger such situations.
>
> The last 2 patches try to improve the page-pinning handling. I included both in
> this series, but obviously only one of them is needed (or we could stack them):
> - 6/7: This waits for up to 150ms for pages to be unpinned
> - 7/7: This isolates pinned pages and replaces them with a fresh copy
>
> Hugh, patch 6 is basically your code. In case that gets merged, can I put your
> Signed-off-by on it?
Hugh, any comments on patch 5, 6 and 7? Those are the last outstanding
issues with memfd+sealing. Patch 7 (isolating pages) is still my
favorite and has been running just fine on my machine for the last
months. I think it'd be nice if we could give it a try in -next. We
can always fall back to Patch 5 or Patch 5+6. Those will detect any
racing AIO and just fail or wait for the IO to finish for a short
period.
Are there any other blockers for this?
Thanks
David
next prev parent reply other threads:[~2014-07-08 16:55 UTC|newest]
Thread overview: 50+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-06-13 10:36 [PATCH v3 0/7] File Sealing & memfd_create() David Herrmann
2014-06-13 10:36 ` [PATCH v3 1/7] mm: allow drivers to prevent new writable mappings David Herrmann
2014-07-09 8:55 ` Hugh Dickins
2014-07-19 16:12 ` David Herrmann
2014-06-13 10:36 ` [PATCH v3 2/7] shm: add sealing API David Herrmann
2014-07-16 10:06 ` Hugh Dickins
2014-07-19 16:17 ` David Herrmann
2014-06-13 10:36 ` [PATCH v3 3/7] shm: add memfd_create() syscall David Herrmann
2014-06-13 12:27 ` Michael Kerrisk (man-pages)
2014-06-13 12:41 ` David Herrmann
2014-06-13 14:20 ` Michael Kerrisk (man-pages)
2014-06-13 16:20 ` John Stultz
2014-06-16 4:12 ` Michael Kerrisk (man-pages)
2014-07-08 18:39 ` David Herrmann
2014-06-15 10:50 ` Jann Horn
2014-07-16 10:07 ` Hugh Dickins
2014-07-19 16:29 ` David Herrmann
2014-06-13 10:36 ` [PATCH v3 4/7] selftests: add memfd_create() + sealing tests David Herrmann
2014-07-16 10:07 ` Hugh Dickins
2014-07-19 16:31 ` David Herrmann
2014-06-13 10:36 ` [PATCH v3 5/7] selftests: add memfd/sealing page-pinning tests David Herrmann
2014-07-16 10:08 ` Hugh Dickins
2014-07-19 16:32 ` David Herrmann
2014-06-13 10:36 ` [RFC v3 6/7] shm: wait for pins to be released when sealing David Herrmann
2014-07-16 10:09 ` Hugh Dickins
2014-07-19 16:36 ` David Herrmann
2014-06-13 10:36 ` [RFC v3 7/7] shm: isolate pinned pages when sealing files David Herrmann
2014-06-13 15:06 ` Andy Lutomirski
2014-06-13 15:27 ` David Herrmann
2014-06-13 17:23 ` Andy Lutomirski
2014-07-09 8:57 ` Hugh Dickins
2014-07-19 16:40 ` David Herrmann
2014-06-13 15:10 ` [PATCH v3 0/7] File Sealing & memfd_create() Andy Lutomirski
2014-06-13 15:15 ` David Herrmann
2014-06-13 15:17 ` Andy Lutomirski
2014-06-13 15:33 ` David Herrmann
2014-06-17 9:54 ` Florian Weimer
2014-06-17 10:01 ` David Herrmann
2014-06-17 10:04 ` Florian Weimer
2014-06-17 10:10 ` David Herrmann
2014-06-17 12:13 ` Florian Weimer
2014-06-17 13:26 ` David Herrmann
[not found] ` <CALCETrVpZ0vFM4usHK+tQhk234Y2jWzB1522kGcGvdQQFAqsZQ@mail.gmail.com>
2014-06-17 16:36 ` David Herrmann
2014-06-17 16:41 ` Andy Lutomirski
2014-06-17 16:51 ` David Herrmann
2014-06-17 17:01 ` Andy Lutomirski
2014-06-17 20:31 ` Hugh Dickins
2014-06-17 21:25 ` Andy Lutomirski
2014-07-08 16:54 ` David Herrmann [this message]
2014-07-09 8:53 ` Hugh Dickins
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