From: Djalal Harouni <tixxdz@gmail.com>
To: Andy Lutomirski <luto@amacapital.net>
Cc: Alexey Gladkov <gladkov.alexey@gmail.com>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Linux API <linux-api@vger.kernel.org>,
"Kirill A. Shutemov" <kirill@shutemov.name>,
Vasiliy Kulikov <segoon@openwall.com>,
Al Viro <viro@zeniv.linux.org.uk>,
"Eric W. Biederman" <ebiederm@xmission.com>,
Oleg Nesterov <oleg@redhat.com>,
Pavel Emelyanov <xemul@parallels.com>,
James Bottomley <James.Bottomley@hansenpartnership.com>
Subject: Re: [RFC] Add option to mount only a pids subset
Date: Thu, 9 Mar 2017 12:26:49 +0100 [thread overview]
Message-ID: <CAEiveUczqzHZG7jcM72oWXAKYZSPJ0ywYEXGDV1sn_FAhr28pA@mail.gmail.com> (raw)
In-Reply-To: <CALCETrVFnSoBP+LvyjN+1qUqrwgZan1nvscq5hV0Ujt_FF2e3g@mail.gmail.com>
On Tue, Mar 7, 2017 at 5:24 PM, Andy Lutomirski <luto@amacapital.net> wrote:
>
> On Mon, Mar 6, 2017 at 3:05 PM, Alexey Gladkov <gladkov.alexey@gmail.com> wrote:
> >
> > After discussion with Oleg Nesterov I reimplement my patch as an additional
> > option for /proc. This option affects the mountpoint. It means that in one
> > pid namespace it possible to have both the whole traditional /proc and
> > /proc with only pids subset.
> >
>
> I like this. I think you should split it into two patches, though:
> one that reworks how procfs gets mounted and one that makes adds the
> new functionality.
>
> Djajal had some concerns about the first part breaking applications
> that use stat and expect certain behavior. This should be manageable,
> though, but making stat work appropriately.
I'm bit lost in the two discussion, however the main concern I was
discussing with Andy was if you have per superblock proc mounts then
each mount will end up with its own device ID st_dev, right now they
share the same ID if they are in the same pid namespace, but if we
change that then we may break the following:
http://man7.org/linux/man-pages/man7/namespaces.7.html
Both new NS_GET_PARENT and NS_GET_USERNS ioctl() that return an fd,
suggests to follow up with fstat() to identify the namespaces..
"By applying fstat(2) to the returned file descriptor, one obtains a
stat structure whose st_dev (resident device) and st_ino (inode
number) fields together identify the owning/parent namespace."
Other /proc/self/ns/* comparison and stat() logic...
Andy suggested that we may have the same st_dev for mounts in the same
pid namespace... I'm not sure which side effect this may bring!
Thanks!
--
tixxdz
next prev parent reply other threads:[~2017-03-09 11:28 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-02-18 22:53 [PATCH] Add pidfs filesystem Alexey Gladkov
2017-02-18 23:34 ` kbuild test robot
2017-02-18 23:34 ` kbuild test robot
2017-02-20 4:05 ` Eric W. Biederman
2017-02-20 10:36 ` Alexey Gladkov
2017-02-22 20:11 ` Richard Weinberger
2017-02-21 14:57 ` Oleg Nesterov
2017-02-22 7:40 ` Pavel Emelyanov
2017-02-22 12:04 ` Alexey Gladkov
2017-02-22 13:08 ` Pavel Emelyanov
2017-02-22 11:53 ` Alexey Gladkov
2017-02-22 15:37 ` Dmitry V. Levin
2017-02-22 17:48 ` Oleg Nesterov
2017-02-22 19:56 ` Alexey Gladkov
2017-03-06 23:05 ` [RFC] Add option to mount only a pids subset Alexey Gladkov
2017-03-07 16:24 ` Andy Lutomirski
2017-03-09 11:26 ` Djalal Harouni [this message]
2017-03-09 20:52 ` Eric W. Biederman
2017-03-11 21:51 ` Alexey Gladkov
2017-03-11 0:05 ` Alexey Gladkov
2017-03-07 17:49 ` Oleg Nesterov
2017-03-10 23:46 ` Alexey Gladkov
2017-03-12 1:54 ` Al Viro
2017-03-12 2:13 ` Al Viro
2017-03-13 3:19 ` Andy Lutomirski
2017-03-13 13:27 ` Al Viro
2017-03-13 15:24 ` Andy Lutomirski
2017-03-23 15:59 ` [PATCH] proc: allow to change proc mount options per mount Djalal Harouni
2017-03-20 12:58 ` [RFC] Add option to mount only a pids subset Alexey Gladkov
2017-03-23 16:05 ` Oleg Nesterov
2017-03-23 22:57 ` Alexey Gladkov
2017-03-23 16:06 ` Djalal Harouni
2017-03-23 22:07 ` Alexey Gladkov
2017-03-26 7:03 ` Djalal Harouni
2017-03-30 21:45 ` Alexey Gladkov
2017-02-27 18:56 ` [PATCH] Add pidfs filesystem Michael Kerrisk
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