public inbox for linux-fsdevel@vger.kernel.org
 help / color / mirror / Atom feed
From: Seth Forshee <seth.forshee@canonical.com>
To: Jan Kara <jack@suse.cz>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>,
	Jann Horn <jannh@google.com>,
	Linux API <linux-api@vger.kernel.org>,
	Linux Containers <containers@lists.linux-foundation.org>,
	Andy Lutomirski <luto@amacapital.net>,
	James Bottomley <James.Bottomley@HansenPartnership.com>,
	Michael Kerrisk <mtk.manpages@gmail.com>,
	linux-fsdevel@vger.kernel.org, Djalal Harouni <tixxdz@gmail.com>
Subject: Re: [PATCH v2 review 09/11] quota: Handle quota data stored in s_user_ns.
Date: Tue, 5 Jul 2016 09:48:14 -0500	[thread overview]
Message-ID: <20160705144814.GB119797@ubuntu-hedt> (raw)
In-Reply-To: <20160704091100.GD5200@quack2.suse.cz>

On Mon, Jul 04, 2016 at 11:11:00AM +0200, Jan Kara wrote:
> On Sat 02-07-16 12:33:29, Eric W. Biederman wrote:
> > In Q_XSETQLIMIT use sb->s_user_ns to detect when we are dealing with
> > the filesystems notion of id 0.
> 
> Hum, is it really usable? Basically the tool calling Q_XSETQLIMIT would
> have to be aware of the namespace the filesystem is mounted in to be able
> to perform the desired operation (and if it gets is wrong, there's
> possibility it would just silently set the timers for some user instead of
> for all users).

Generally userspace does not need to be aware of the namespace. The user
id passed from userspace is translated based on its namespace, and if
that kqid doesn't map into s_user_ns the Q_XSETQLIM operation fails.

But it requires going to some trouble and having CAP_SYS_ADMIN towards
the relevant namespaces to give processes not in s_user_ns visibility to
the mount, so that isn't going to be a common scenario. If some user
does set up such a scenario then it doesn't seem to be asking too much
for them to be aware of the limitations.

Thanks,
Seth


  reply	other threads:[~2016-07-05 14:48 UTC|newest]

Thread overview: 58+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-07-02 17:18 [PATCH review 0/11] General unprivileged mount support Eric W. Biederman
2016-07-02 17:20 ` [PATCH review 01/11] fs: Refuse uid/gid changes which don't map into s_user_ns Eric W. Biederman
2016-07-02 17:20   ` [PATCH review 02/11] userns: Handle -1 in k[ug]id_has_mapping when !CONFIG_USER_NS Eric W. Biederman
2016-07-02 17:20   ` [PATCH review 03/11] vfs: Verify acls are valid within superblock's s_user_ns Eric W. Biederman
2016-07-02 17:20   ` [PATCH review 04/11] fs: Check for invalid i_uid in may_follow_link() Eric W. Biederman
2016-07-02 17:20   ` [PATCH review 05/11] cred: Reject inodes with invalid ids in set_create_file_as() Eric W. Biederman
2016-07-02 17:20   ` [PATCH review 06/11] vfs: Don't modify inodes with a uid or gid unknown to the vfs Eric W. Biederman
2016-07-02 17:20   ` [PATCH review 07/11] vfs: Don't create " Eric W. Biederman
2016-07-04  7:59     ` Jan Kara
2016-07-05 14:55       ` Eric W. Biederman
2016-07-06  9:07         ` Jan Kara
2016-07-06 15:37           ` Eric W. Biederman
2016-07-02 17:20   ` [PATCH review 08/11] quota: Ensure qids map to the filesystem Eric W. Biederman
2016-07-02 17:20   ` [PATCH review 09/11] quota: Handle quota data stored in s_user_ns Eric W. Biederman
2016-07-02 17:33     ` [PATCH v2 " Eric W. Biederman
2016-07-04  9:11       ` Jan Kara
2016-07-05 14:48         ` Seth Forshee [this message]
2016-07-05 15:34         ` Eric W. Biederman
2016-07-05 20:57           ` Dave Chinner
2016-07-05 21:28             ` Eric W. Biederman
2016-07-06  6:35               ` Dave Chinner
2016-07-06  8:25                 ` Jan Kara
2016-07-06 17:51                   ` Eric W. Biederman
2016-07-02 17:20   ` [PATCH review 10/11] evm: Translate user/group ids relative to s_user_ns when computing HMAC Eric W. Biederman
2016-07-02 17:20   ` [PATCH review 11/11] fs: Update i_[ug]id_(read|write) to translate relative to s_user_ns Eric W. Biederman
2016-07-04  8:52 ` [PATCH review 0/11] General unprivileged mount support Jan Kara
2016-07-04 16:27   ` Eric W. Biederman
2016-07-06  8:54     ` Jan Kara
2016-07-06 13:54       ` Seth Forshee
2016-07-06 14:22         ` Jan Kara
2016-07-06 14:46           ` Seth Forshee
2016-07-06 15:01           ` Eric W. Biederman
2016-07-06 15:23           ` James Bottomley
2016-07-06 16:35             ` Eric W. Biederman
2016-07-06 13:44 ` Andy Lutomirski
2016-07-06 15:21   ` Eric W. Biederman
2016-07-06 14:01 ` Andy Lutomirski
2016-07-06 15:19   ` Eric W. Biederman
2016-07-06 18:10 ` [PATCH review 0/12] General unprivileged mount support v2 Eric W. Biederman
2016-07-06 18:12   ` [PATCH review 01/12] fs: Refuse uid/gid changes which don't map into s_user_ns Eric W. Biederman
2016-07-06 18:12     ` [PATCH review 02/12] userns: Handle -1 in k[ug]id_has_mapping when !CONFIG_USER_NS Eric W. Biederman
2016-07-06 18:12     ` [PATCH review 03/12] vfs: Verify acls are valid within superblock's s_user_ns Eric W. Biederman
2016-07-06 18:12     ` [PATCH review 04/12] fs: Check for invalid i_uid in may_follow_link() Eric W. Biederman
2016-07-06 18:12     ` [PATCH review 05/12] cred: Reject inodes with invalid ids in set_create_file_as() Eric W. Biederman
2016-07-06 18:12     ` [PATCH review 06/12] vfs: Don't modify inodes with a uid or gid unknown to the vfs Eric W. Biederman
2016-07-06 18:12     ` [PATCH review 07/12] vfs: Don't create " Eric W. Biederman
2016-07-06 18:12     ` [PATCH review 08/12] quota: Ensure qids map to the filesystem Eric W. Biederman
2016-07-11 10:14       ` Jan Kara
2016-07-11 18:12         ` Eric W. Biederman
2016-07-13  1:34           ` Dave Chinner
2016-07-13  3:45             ` Dave Chinner
2016-07-13  5:43             ` Jann Horn
2016-07-14 17:03               ` Eric W. Biederman
2016-07-06 18:12     ` [PATCH review 09/12] quota: Handle quota data stored in s_user_ns in quota_setxquota Eric W. Biederman
2016-07-06 18:12     ` [PATCH review 10/12] dquot: For now explicitly don't support filesystems outside of init_user_ns Eric W. Biederman
2016-07-11 10:09       ` Jan Kara
2016-07-06 18:12     ` [PATCH review 11/12] evm: Translate user/group ids relative to s_user_ns when computing HMAC Eric W. Biederman
2016-07-06 18:12     ` [PATCH review 12/12] fs: Update i_[ug]id_(read|write) to translate relative to s_user_ns 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=20160705144814.GB119797@ubuntu-hedt \
    --to=seth.forshee@canonical.com \
    --cc=James.Bottomley@HansenPartnership.com \
    --cc=containers@lists.linux-foundation.org \
    --cc=ebiederm@xmission.com \
    --cc=jack@suse.cz \
    --cc=jannh@google.com \
    --cc=linux-api@vger.kernel.org \
    --cc=linux-fsdevel@vger.kernel.org \
    --cc=luto@amacapital.net \
    --cc=mtk.manpages@gmail.com \
    --cc=tixxdz@gmail.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