From: Alban Crequy <alban.crequy@gmail.com>
To: Kirill Tkhai <ktkhai@virtuozzo.com>
Cc: Andrey Vagin <avagin@openvz.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
linux-fsdevel@vger.kernel.org,
"Eric W. Biederman" <ebiederm@xmission.com>,
Cyrill Gorcunov <gorcunov@openvz.org>,
Alexander Viro <viro@zeniv.linux.org.uk>,
Michael Kerrisk-manpages <mtk.manpages@gmail.com>,
Linux API <linux-api@vger.kernel.org>
Subject: Re: [PATCH 2/2] pidns: Expose task pid_ns_for_children to userspace
Date: Mon, 23 Jan 2017 22:49:14 +0100 [thread overview]
Message-ID: <CAMXgnP7gs_SXTj3yLFSM9DVfmN09m7q0hYQN-9oa3aV4eYgw5w@mail.gmail.com> (raw)
In-Reply-To: <148440329770.30622.16593902895676160550.stgit@localhost.localdomain>
On 14 January 2017 at 15:15, Kirill Tkhai <ktkhai@virtuozzo.com> wrote:
> For correct checkpointing/restoring of a task from userspace
> it's need to know the task's pid_ns_for_children. Currently,
> there is no a sane way to do that (the only possible trick
> is to force the task create a new child and to analize the
> child's /proc/[pid]/ns/pid link, that is performance-stupid).
>
> The patch exposes pid_ns_for_children to ns directory
> in standard way with the name "pid_for_children":
>
> ~# ls /proc/5531/ns -l | grep pid
> lrwxrwxrwx 1 root root 0 Jan 14 16:38 pid -> pid:[4026531836]
> lrwxrwxrwx 1 root root 0 Jan 14 16:38 pid_for_children -> pid:[4026532286]
>
> Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
What's happening if a process, after unsharing CLONE_NEWPID, does not
fork but instead let another process open the new "pid_for_children"
and then setns()+fork()? Is that other process allowed to create the
"pid 1" in the new pid namespaces? Is that also allowed if the other
process lives in a sibling pid namespace? If so, that would break what
pid_namespaces(7) says:
"the parental relationship between processes mirrors the parental
relationship between PID namespaces: the parent of a process is
either in the same namespace or resides in the immediate parent
PID namespace."
next prev parent reply other threads:[~2017-01-23 21:49 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-01-14 14:14 [PATCH 1/2] ns: Allow ns_entries to have custom symlink content Kirill Tkhai
2017-01-14 14:15 ` [PATCH 2/2] pidns: Expose task pid_ns_for_children to userspace Kirill Tkhai
2017-01-17 20:00 ` Andrei Vagin
2017-01-23 21:49 ` Alban Crequy [this message]
2017-01-24 8:35 ` Kirill Tkhai
2017-01-30 15:10 ` Kirill Tkhai
2017-01-16 8:18 ` [PATCH 1/2] ns: Allow ns_entries to have custom symlink content Cyrill Gorcunov
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=CAMXgnP7gs_SXTj3yLFSM9DVfmN09m7q0hYQN-9oa3aV4eYgw5w@mail.gmail.com \
--to=alban.crequy@gmail.com \
--cc=avagin@openvz.org \
--cc=ebiederm@xmission.com \
--cc=gorcunov@openvz.org \
--cc=ktkhai@virtuozzo.com \
--cc=linux-api@vger.kernel.org \
--cc=linux-fsdevel@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=mtk.manpages@gmail.com \
--cc=viro@zeniv.linux.org.uk \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).