From: ebiederm@xmission.com (Eric W. Biederman)
To: David Howells <dhowells@redhat.com>
Cc: "Serge E. Hallyn" <serge@hallyn.com>,
LSM <linux-security-module@vger.kernel.org>,
Andrew Morton <akpm@osdl.org>, James Morris <jmorris@namei.org>,
Kees Cook <kees.cook@canonical.com>,
containers@lists.linux-foundation.org,
kernel list <linux-kernel@vger.kernel.org>,
Alexey Dobriyan <adobriyan@gmail.com>,
Michael Kerrisk <mtk.manpages@gmail.com>,
xemul@parallels.com
Subject: Re: [PATCH 1/9] Add a user_namespace as creator/owner of uts_namespace
Date: Wed, 23 Feb 2011 15:54:12 -0800 [thread overview]
Message-ID: <m162sagvdn.fsf@fess.ebiederm.org> (raw)
In-Reply-To: <8559.1298503148@redhat.com> (David Howells's message of "Wed, 23 Feb 2011 23:19:08 +0000")
David Howells <dhowells@redhat.com> writes:
> Eric W. Biederman <ebiederm@xmission.com> wrote:
>
>> > Which means that unless the uts_namespace belongs to our user_namespace, we
>> > cannot change it. Is that correct?
>>
>> No. If you are root in a parent namespace you can also change it.
>
> But surely, by definition, if you're a user in this namespace, you can't also
> be root in a parent namespace...
To be clear the case you looked at was:
> - if (!capable(CAP_SYS_ADMIN))
> + if (!ns_capable(current->nsproxy->uts_ns->user_ns, CAP_SYS_ADMIN))
>
> what is it you're actually asking? I presume it's 'does this user have
> CAP_SYS_ADMIN capability over objects belonging to the uts_namespace's
> user_namespace?'
Here "current->nsproxy->uts_ns->user_ns" (the target_ns value) is only
refers to the uts_ns we are talking about.
The user itself comes from current_user().
> For the case I worked through current_user() is a member of current_user_ns()
> and can't also be a member of its parent, grandparent, etc. - or can
> it?
Right now if you are looking at current_user() because of limitations in
the creation ordering I think you are correct.
However in the near term pile of changes to merge, are the syscalls for
joining an existing namespace. At which point there is no reason in
general to suppose the current limitations of creation apply.
Although it is conceivable that unshare of namespaces can also get you
to someplace similar to joining prexisting namespaces.
Eric
next prev parent reply other threads:[~2011-02-23 23:54 UTC|newest]
Thread overview: 68+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-02-17 15:02 userns: targeted capabilities v5 Serge E. Hallyn
2011-02-17 15:02 ` [PATCH 1/9] Add a user_namespace as creator/owner of uts_namespace Serge E. Hallyn
2011-02-18 3:31 ` Eric W. Biederman
2011-02-18 16:57 ` Daniel Lezcano
2011-02-18 23:59 ` Andrew Morton
2011-02-23 17:16 ` David Howells
2011-02-23 21:21 ` Eric W. Biederman
2011-02-23 23:19 ` David Howells
2011-02-23 23:54 ` Eric W. Biederman [this message]
2011-02-17 15:03 ` [PATCH 2/9] security: Make capabilities relative to the user namespace Serge E. Hallyn
2011-02-18 3:46 ` Eric W. Biederman
2011-02-18 23:44 ` Daniel Lezcano
2011-02-18 23:59 ` Andrew Morton
2011-02-23 11:40 ` David Howells
2011-02-23 12:01 ` David Howells
2011-02-23 13:43 ` Serge E. Hallyn
2011-02-23 16:59 ` David Howells
2011-02-17 15:03 ` [PATCH 3/9] allow sethostname in a container Serge E. Hallyn
2011-02-18 3:05 ` Eric W. Biederman
2011-02-18 23:46 ` Daniel Lezcano
2011-02-17 15:03 ` [PATCH 4/9] allow killing tasks in your own or child userns Serge E. Hallyn
2011-02-18 3:00 ` Eric W. Biederman
2011-02-18 23:59 ` Andrew Morton
2011-02-24 0:48 ` Serge E. Hallyn
2011-02-24 0:54 ` Andrew Morton
2011-02-19 10:55 ` Daniel Lezcano
2011-02-17 15:03 ` [PATCH 5/9] Allow ptrace from non-init user namespaces Serge E. Hallyn
2011-02-18 2:59 ` Eric W. Biederman
2011-02-18 4:36 ` Serge E. Hallyn
2011-02-24 0:49 ` [PATCH] userns: ptrace: incorporate feedback from Eric Serge E. Hallyn
2011-02-24 0:56 ` Andrew Morton
2011-02-24 3:15 ` Serge E. Hallyn
2011-02-18 23:59 ` [PATCH 5/9] Allow ptrace from non-init user namespaces Andrew Morton
2011-02-24 0:43 ` Serge E. Hallyn
2011-02-19 17:49 ` Daniel Lezcano
2011-02-23 17:05 ` David Howells
2011-02-23 17:11 ` David Howells
2011-02-17 15:03 ` [PATCH 6/9] user namespaces: convert all capable checks in kernel/sys.c Serge E. Hallyn
2011-02-18 1:57 ` Eric W. Biederman
2011-02-18 23:59 ` Andrew Morton
2011-02-19 0:01 ` Andrew Morton
2011-02-19 17:52 ` Daniel Lezcano
2011-02-17 15:03 ` [PATCH 7/9] add a user namespace owner of ipc ns Serge E. Hallyn
2011-02-18 3:19 ` Eric W. Biederman
2011-02-18 23:59 ` Andrew Morton
2011-02-19 17:57 ` Daniel Lezcano
2011-02-17 15:03 ` [PATCH 8/9] user namespaces: convert several capable() calls Serge E. Hallyn
2011-02-18 1:51 ` Eric W. Biederman
2011-02-19 19:07 ` Daniel Lezcano
2011-02-17 15:04 ` [PATCH 9/9] userns: check user namespace for task->file uid equivalence checks Serge E. Hallyn
2011-02-18 1:29 ` Eric W. Biederman
2011-02-18 23:59 ` Andrew Morton
2011-02-24 3:24 ` Serge E. Hallyn
2011-02-24 5:08 ` Andrew Morton
2011-02-19 19:22 ` Daniel Lezcano
2011-02-18 0:21 ` userns: targeted capabilities v5 Andrew Morton
2011-02-18 3:53 ` Eric W. Biederman
2011-02-18 4:28 ` Serge E. Hallyn
2011-02-23 12:05 ` User namespaces and keys David Howells
2011-02-23 13:58 ` Serge E. Hallyn
2011-02-23 14:46 ` Eric W. Biederman
2011-02-23 15:06 ` David Howells
2011-02-23 15:45 ` Eric W. Biederman
2011-02-23 15:53 ` Serge E. Hallyn
2011-02-23 19:24 ` Casey Schaufler
2011-02-23 20:55 ` Eric W. Biederman
2011-02-23 21:37 ` Casey Schaufler
2011-02-24 6:56 ` Eric W. Biederman
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=m162sagvdn.fsf@fess.ebiederm.org \
--to=ebiederm@xmission.com \
--cc=adobriyan@gmail.com \
--cc=akpm@osdl.org \
--cc=containers@lists.linux-foundation.org \
--cc=dhowells@redhat.com \
--cc=jmorris@namei.org \
--cc=kees.cook@canonical.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-security-module@vger.kernel.org \
--cc=mtk.manpages@gmail.com \
--cc=serge@hallyn.com \
--cc=xemul@parallels.com \
/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).