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From: Tycho Andersen <tycho@tycho.ws>
To: "Serge E. Hallyn" <serge@hallyn.com>
Cc: "Christian Brauner" <christian.brauner@ubuntu.com>,
	"Stéphane Graber" <stgraber@ubuntu.com>,
	"Eric W. Biederman" <ebiederm@xmission.com>,
	"Aleksa Sarai" <cyphar@cyphar.com>,
	"Jann Horn" <jannh@google.com>,
	smbarber@chromium.org,
	"Seth Forshee" <seth.forshee@canonical.com>,
	"Alexander Viro" <viro@zeniv.linux.org.uk>,
	"Alexey Dobriyan" <adobriyan@gmail.com>,
	"James Morris" <jmorris@namei.org>,
	"Kees Cook" <keescook@chromium.org>,
	"Jonathan Corbet" <corbet@lwn.net>,
	"Phil Estes" <estesp@gmail.com>,
	linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
	containers@lists.linux-foundation.org,
	linux-security-module@vger.kernel.org, linux-api@vger.kernel.org
Subject: Re: [PATCH v3 00/25] user_namespace: introduce fsid mappings
Date: Wed, 19 Feb 2020 14:56:23 -0700	[thread overview]
Message-ID: <20200219215623.GA11724@cisco> (raw)
In-Reply-To: <20200219214837.GA29159@mail.hallyn.com>

On Wed, Feb 19, 2020 at 03:48:37PM -0600, Serge E. Hallyn wrote:
> On Wed, Feb 19, 2020 at 01:35:58PM -0600, Serge E. Hallyn wrote:
> > On Tue, Feb 18, 2020 at 03:33:46PM +0100, Christian Brauner wrote:
> > > With fsid mappings we can solve this by writing an id mapping of 0
> > > 100000 100000 and an fsid mapping of 0 300000 100000. On filesystem
> > > access the kernel will now lookup the mapping for 300000 in the fsid
> > > mapping tables of the user namespace. And since such a mapping exists,
> > > the corresponding files will have correct ownership.
> > 
> > So if I have
> > 
> > /proc/self/uid_map: 0 100000 100000
> > /proc/self/fsid_map: 1000 1000 1
> 
> Oh, sorry.  Your explanation in 20/25 i think set me straight, though I need
> to think through a few more examples.
> 
> ...
> 
> > 3. If I create a new file, as nsuid 1000, what will be the inode owning kuid?
> 
> (Note - I edited the quoted txt above to be more precise)
> 
> I'm still not quite clear on this.  I believe the fsid mapping will take
> precedence so it'll be uid 1000 ?  Per mount behavior would be nice there,
> but perhaps unwieldy.

The is_userns_visible() bits seems to be an attempt at understanding
what people would want per-mount, with a policy hard coded in the
kernel.

But maybe per-mount behavior can be solved more elegantly with shifted
bind mounts, so we can drop all that from this series, and ignore
per-mount settings here?

Tycho

  reply	other threads:[~2020-02-19 21:56 UTC|newest]

Thread overview: 51+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-18 14:33 [PATCH v3 00/25] user_namespace: introduce fsid mappings Christian Brauner
2020-02-18 14:33 ` [PATCH v3 01/25] user_namespace: introduce fsid mappings infrastructure Christian Brauner
2020-02-19  2:33   ` Serge E. Hallyn
2020-02-18 14:33 ` [PATCH v3 02/25] proc: add /proc/<pid>/fsuid_map Christian Brauner
2020-02-19  2:33   ` Serge E. Hallyn
2020-02-18 14:33 ` [PATCH v3 03/25] proc: add /proc/<pid>/fsgid_map Christian Brauner
2020-02-19  2:33   ` Serge E. Hallyn
2020-02-18 14:33 ` [PATCH v3 04/25] fsuidgid: add fsid mapping helpers Christian Brauner
2020-02-18 14:33 ` [PATCH v3 05/25] user_namespace: refactor map_write() Christian Brauner
2020-02-19  2:35   ` Serge E. Hallyn
2020-02-18 14:33 ` [PATCH v3 06/25] user_namespace: make map_write() support fsid mappings Christian Brauner
2020-02-19 16:18   ` Jann Horn
2020-02-18 14:33 ` [PATCH v3 07/25] proc: task_state(): use from_kfs{g,u}id_munged Christian Brauner
2020-02-19  2:36   ` Serge E. Hallyn
2020-02-18 14:33 ` [PATCH v3 08/25] cred: add kfs{g,u}id Christian Brauner
2020-02-18 14:33 ` [PATCH v3 09/25] fs: add is_userns_visible() helper Christian Brauner
2020-02-19  2:42   ` Serge E. Hallyn
2020-02-19 12:06     ` Christian Brauner
2020-02-19 17:18       ` Andy Lutomirski
2020-02-20 14:26         ` Serge E. Hallyn
2020-02-18 14:33 ` [PATCH v3 10/25] namei: may_{o_}create(): handle fsid mappings Christian Brauner
2020-02-18 14:33 ` [PATCH v3 11/25] inode: inode_owner_or_capable(): " Christian Brauner
2020-02-18 22:25   ` Christoph Hellwig
2020-02-19 12:29     ` Christian Brauner
2020-02-18 14:33 ` [PATCH v3 12/25] capability: privileged_wrt_inode_uidgid(): " Christian Brauner
2020-02-18 14:33 ` [PATCH v3 13/25] stat: " Christian Brauner
2020-02-18 14:34 ` [PATCH v3 14/25] open: " Christian Brauner
2020-02-18 14:34 ` [PATCH v3 15/25] posix_acl: " Christian Brauner
2020-02-18 22:26   ` Christoph Hellwig
2020-02-19 12:56     ` Christian Brauner
2020-02-18 14:34 ` [PATCH v3 16/25] attr: notify_change(): " Christian Brauner
2020-02-18 14:34 ` [PATCH v3 17/25] commoncap: cap_bprm_set_creds(): " Christian Brauner
2020-02-18 14:34 ` [PATCH v3 18/25] commoncap: cap_task_fix_setuid(): " Christian Brauner
2020-02-18 14:34 ` [PATCH v3 19/25] commoncap: handle fsid mappings with vfs caps Christian Brauner
2020-02-19 15:53   ` Jann Horn
2020-02-18 14:34 ` [PATCH v3 20/25] exec: bprm_fill_uid(): handle fsid mappings Christian Brauner
2020-02-18 14:34 ` [PATCH v3 21/25] ptrace: adapt ptrace_may_access() to always uses unmapped fsids Christian Brauner
2020-02-18 14:34 ` [PATCH v3 22/25] devpts: handle fsid mappings Christian Brauner
2020-02-18 14:34 ` [PATCH v3 23/25] keys: " Christian Brauner
2020-02-18 14:34 ` [PATCH v3 24/25] sys: handle fsid mappings in set*id() calls Christian Brauner
2020-02-19 15:42   ` Jann Horn
2020-02-18 14:34 ` [PATCH v3 25/25] selftests: add simple fsid mapping selftests Christian Brauner
2020-02-18 23:50 ` [PATCH v3 00/25] user_namespace: introduce fsid mappings James Bottomley
2020-02-19 12:27   ` Christian Brauner
2020-02-19 15:36     ` James Bottomley
2020-02-19 15:33 ` Jann Horn
2020-02-19 19:35 ` Serge E. Hallyn
2020-02-19 21:48   ` Serge E. Hallyn
2020-02-19 21:56     ` Tycho Andersen [this message]
2020-02-27 19:33 ` Josef Bacik
2020-03-02 14:34   ` Serge E. Hallyn

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