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Re: [PATCH v3 0/7] User namespace mount updates

From Octavian Purdila <octavian.purdila@intel.com>
Newsgroups linux.kernel
Subject Re: [PATCH v3 0/7] User namespace mount updates
Date 2015-11-19 17:20 +0100
Message-ID <qwA6e-3ds-9@gated-at.bofh.it> (permalink)
References (6 earlier) <qvU6Z-N7-13@gated-at.bofh.it> <qvU6Z-N7-11@gated-at.bofh.it> <qvUTn-1l2-1@gated-at.bofh.it> <qvWBR-2uT-13@gated-at.bofh.it> <qwzjQ-2Fh-23@gated-at.bofh.it>
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On Thu, Nov 19, 2015 at 5:23 PM, Seth Forshee
<seth.forshee@canonical.com> wrote:
> On Wed, Nov 18, 2015 at 12:00:17AM +0200, Octavian Purdila wrote:
>> On Tue, Nov 17, 2015 at 10:12 PM, Richard Weinberger <richard@nod.at> wrote:
>> > Am 17.11.2015 um 20:25 schrieb Octavian Purdila:
>> >> On Tue, Nov 17, 2015 at 9:21 PM, Seth Forshee
>> >> <seth.forshee@canonical.com> wrote:
>> >>>
>> >>> On Tue, Nov 17, 2015 at 08:12:31PM +0100, Richard Weinberger wrote:
>> >>>> On Tue, Nov 17, 2015 at 7:34 PM, Seth Forshee
>> >>>> <seth.forshee@canonical.com> wrote:
>> >>>>> On Tue, Nov 17, 2015 at 05:55:06PM +0000, Al Viro wrote:
>> >>>>>> On Tue, Nov 17, 2015 at 11:25:51AM -0600, Seth Forshee wrote:
>> >>>>>>
>> >>>>>>> Shortly after that I plan to follow with support for ext4. I've been
>> >>>>>>> fuzzing ext4 for a while now and it has held up well, and I'm currently
>> >>>>>>> working on hand-crafted attacks. Ted has commented privately (to others,
>> >>>>>>> not to me personally) that he will fix bugs for such attacks, though I
>> >>>>>>> haven't seen any public comments to that effect.
>> >>>>>>
>> >>>>>> _Static_ attacks, or change-image-under-mounted-fs attacks?
>> >>>>>
>> >>>>> Right now only static attacks, change-image-under-mounted-fs attacks
>> >>>>> will be next.
>> >>>>
>> >>>> Do we *really* need to enable unprivileged mounting of kernel filesystems?
>> >>>> What about just enabling fuse and implement ext4 and friends as fuse
>> >>>> filesystems?
>> >>>> Using the approaching Linux Kernel Libary[1] this is easy.
>> >>>
>> >>> I haven't looked at this project, but I'm guessing that programs must be
>> >>> written specifically to make use of it? I.e. you can't just use the
>> >>> mount syscall, and thus all existing software still doesn't work?
>> >>>
>> >>
>> >> The projects includes a lklfuse program that uses fuse to mount a
>> >> fileystem image.
>> >
>> > Cool. I gave it a try.
>> > It seems to work fine, but only if I run it in foreground (using -d)
>> > otherwise fuse blocks every filesystem request.
>> >
>>
>> Now it should work in the background as well, thanks for reporting the issue.
>

Hi Seth,

> I'm playing with lklfuse now, it's surprisingly easy to get up and
> running. I did have a few problems though that I thought you'd like to
> know about.
>

Great, thanks for giving it a try and reporting the issues.

> Unfortunately I still can't run it in background mode, I get a segfault.

I got it to reproduce as well now. Not sure why how it worked before,
probably a race condition between lkl initialization and fuse calls.

> It's working fine on light workloads, but I'm having issues when I start
> trying to stress it. In a couple runs of the stress-ng filesystem
> stressors I saw both stress-ng and lklfuse get stuck in uninterruptible
> sleep during the first run, and during the second I got some OOM errors
> in lklfuse followed by I/O errors and eventually a journal error that
> cause the filesystem to go read-only.
>
> The command I used for the first run was:
>
>  stress-ng --class filesystem --all 0
>

I will reproduce it and take a look.

> And for the second:
>
>  stress-ng --class filesystem --seq 0 -v -t 60
>
> There really wasn't anything interesting in the lklfuse output for the
> first run, but for the second run I pasted the output here:
> http://paste.ubuntu.com/13346993/

lklfuse allocates a fixed 100MB to the kernel and this is probably not
enough. For the short term I can add a parameter to lklfuse that
allows the user to specify the amount of memory to allocate to lkl. A
better fix would probably be to dynamically adjust the memory size of
lkl. I am thinking of using the ballon virtio driver or the memory
hotplug infrastructure. Any other suggestions?

I created a couple of issues in github [1] that you can track if you
want - I want to avoid spamming the list with reporting progress on
them.

[1] https://github.com/lkl/linux/issues
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Thread

[PATCH v3 0/7] User namespace mount updates Seth Forshee <seth.forshee@canonical.com> - 2015-11-17 17:50 +0100
  [PATCH v3 1/7] block_dev: Support checking inode permissions in lookup_bdev() Seth Forshee <seth.forshee@canonical.com> - 2015-11-17 17:50 +0100
  [PATCH v3 2/7] block_dev: Check permissions towards block device inode when mounting Seth Forshee <seth.forshee@canonical.com> - 2015-11-17 17:50 +0100
  [PATCH v3 3/7] mtd: Check permissions towards mtd block device inode when mounting Seth Forshee <seth.forshee@canonical.com> - 2015-11-17 17:50 +0100
  Re: [PATCH v3 0/7] User namespace mount updates Al Viro <viro@ZenIV.linux.org.uk> - 2015-11-17 18:10 +0100
    Re: [PATCH v3 0/7] User namespace mount updates Seth Forshee <seth.forshee@canonical.com> - 2015-11-17 18:30 +0100
      Re: [PATCH v3 0/7] User namespace mount updates "Serge E. Hallyn" <serge@hallyn.com> - 2015-11-17 18:50 +0100
      Re: [PATCH v3 0/7] User namespace mount updates Al Viro <viro@ZenIV.linux.org.uk> - 2015-11-17 19:00 +0100
        Re: [PATCH v3 0/7] User namespace mount updates Seth Forshee <seth.forshee@canonical.com> - 2015-11-17 19:40 +0100
          Re: [PATCH v3 0/7] User namespace mount updates Richard Weinberger <richard.weinberger@gmail.com> - 2015-11-17 20:20 +0100
            Re: [PATCH v3 0/7] User namespace mount updates Octavian Purdila <octavian.purdila@intel.com> - 2015-11-17 20:30 +0100
              Re: [PATCH v3 0/7] User namespace mount updates Richard Weinberger <richard@nod.at> - 2015-11-17 21:20 +0100
                Re: [PATCH v3 0/7] User namespace mount updates Octavian Purdila <octavian.purdila@intel.com> - 2015-11-17 23:10 +0100
                Re: [PATCH v3 0/7] User namespace mount updates Seth Forshee <seth.forshee@canonical.com> - 2015-11-19 16:30 +0100
                Re: [PATCH v3 0/7] User namespace mount updates Octavian Purdila <octavian.purdila@intel.com> - 2015-11-19 17:20 +0100
                Re: [PATCH v3 0/7] User namespace mount updates Seth Forshee <seth.forshee@canonical.com> - 2015-11-19 17:40 +0100
                Re: [PATCH v3 0/7] User namespace mount updates "Serge E. Hallyn" <serge.hallyn@ubuntu.com> - 2015-11-20 18:40 +0100
            Re: [PATCH v3 0/7] User namespace mount updates Richard Weinberger <richard@nod.at> - 2015-11-17 20:30 +0100
            Re: [PATCH v3 0/7] User namespace mount updates Seth Forshee <seth.forshee@canonical.com> - 2015-11-17 20:30 +0100
          Re: [PATCH v3 0/7] User namespace mount updates Theodore Ts'o <tytso@mit.edu> - 2015-11-18 20:20 +0100
            Re: [PATCH v3 0/7] User namespace mount updates Seth Forshee <seth.forshee@canonical.com> - 2015-11-18 20:30 +0100
            Re: [PATCH v3 0/7] User namespace mount updates Serge Hallyn <serge.hallyn@ubuntu.com> - 2015-11-18 20:40 +0100
        Re: [PATCH v3 0/7] User namespace mount updates Austin S Hemmelgarn <ahferroin7@gmail.com> - 2015-11-17 20:10 +0100
          Re: [PATCH v3 0/7] User namespace mount updates Seth Forshee <seth.forshee@canonical.com> - 2015-11-17 20:20 +0100
            Re: [PATCH v3 0/7] User namespace mount updates Austin S Hemmelgarn <ahferroin7@gmail.com> - 2015-11-17 22:00 +0100
              Re: [PATCH v3 0/7] User namespace mount updates Seth Forshee <seth.forshee@canonical.com> - 2015-11-17 22:40 +0100
                Re: [PATCH v3 0/7] User namespace mount updates Austin S Hemmelgarn <ahferroin7@gmail.com> - 2015-11-18 13:30 +0100
                Re: [PATCH v3 0/7] User namespace mount updates Seth Forshee <seth.forshee@canonical.com> - 2015-11-18 15:30 +0100
                Re: [PATCH v3 0/7] User namespace mount updates Al Viro <viro@ZenIV.linux.org.uk> - 2015-11-18 16:00 +0100
                Re: [PATCH v3 0/7] User namespace mount updates Seth Forshee <seth.forshee@canonical.com> - 2015-11-18 16:10 +0100
                Re: [PATCH v3 0/7] User namespace mount updates Al Viro <viro@ZenIV.linux.org.uk> - 2015-11-18 16:20 +0100
                Re: [PATCH v3 0/7] User namespace mount updates Richard Weinberger <richard.weinberger@gmail.com> - 2015-11-18 16:30 +0100
                Re: [PATCH v3 0/7] User namespace mount updates James Morris <jmorris@namei.org> - 2015-11-19 08:50 +0100
                Re: [PATCH v3 0/7] User namespace mount updates Richard Weinberger <richard@nod.at> - 2015-11-19 09:00 +0100
                Re: [PATCH v3 0/7] User namespace mount updates "Serge E. Hallyn" <serge.hallyn@ubuntu.com> - 2015-11-19 15:30 +0100
                Re: [PATCH v3 0/7] User namespace mount updates Richard Weinberger <richard@nod.at> - 2015-11-19 16:10 +0100
                Re: [PATCH v3 0/7] User namespace mount updates Colin Walters <walters@verbum.org> - 2015-11-19 15:40 +0100
                Re: [PATCH v3 0/7] User namespace mount updates Richard Weinberger <richard@nod.at> - 2015-11-19 15:50 +0100
                Re: [PATCH v3 0/7] User namespace mount updates "Richard W.M. Jones" <rjones@redhat.com> - 2015-11-19 16:20 +0100
                Re: [PATCH v3 0/7] User namespace mount updates "Serge E. Hallyn" <serge.hallyn@ubuntu.com> - 2015-11-19 16:00 +0100
                Re: [PATCH v3 0/7] User namespace mount updates Nikolay Borisov <kernel@kyup.com> - 2015-11-18 16:40 +0100
                Re: [PATCH v3 0/7] User namespace mount updates Austin S Hemmelgarn <ahferroin7@gmail.com> - 2015-11-18 16:40 +0100
          Re: [PATCH v3 0/7] User namespace mount updates Al Viro <viro@ZenIV.linux.org.uk> - 2015-11-17 20:40 +0100
            Re: [PATCH v3 0/7] User namespace mount updates Austin S Hemmelgarn <ahferroin7@gmail.com> - 2015-11-17 21:40 +0100
              Re: [PATCH v3 0/7] User namespace mount updates Al Viro <viro@ZenIV.linux.org.uk> - 2015-11-17 22:10 +0100
                Re: [PATCH v3 0/7] User namespace mount updates Seth Forshee <seth.forshee@canonical.com> - 2015-11-17 23:10 +0100
                Re: [PATCH v3 0/7] User namespace mount updates Austin S Hemmelgarn <ahferroin7@gmail.com> - 2015-11-18 13:50 +0100
                Re: [PATCH v3 0/7] User namespace mount updates Seth Forshee <seth.forshee@canonical.com> - 2015-11-18 15:40 +0100
                Re: [PATCH v3 0/7] User namespace mount updates Austin S Hemmelgarn <ahferroin7@gmail.com> - 2015-11-18 16:40 +0100
            Re: [PATCH v3 0/7] User namespace mount updates bfields@fieldses.org (J. Bruce Fields) - 2015-11-18 19:50 +0100

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