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From: Greg Kurz <groug@kaod.org>
To: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
Cc: linux-fsdevel@vger.kernel.org, stefanha@redhat.com,
	mszeredi@redhat.com, vgoyal@redhat.com, gscrivan@redhat.com,
	dwalsh@redhat.com, chirantan@chromium.org,
	Christian Schoenebeck <schoenebeck@crudebyte.com>
Subject: Re: xattr names for unprivileged stacking?
Date: Tue, 28 Jul 2020 15:08:59 +0200	[thread overview]
Message-ID: <20200728150859.0ad6ea79@bahia.lan> (raw)
In-Reply-To: <20200728105503.GE2699@work-vm>

On Tue, 28 Jul 2020 11:55:03 +0100
"Dr. David Alan Gilbert" <dgilbert@redhat.com> wrote:

> Hi,
>   Are there any standards for mapping xattr names/classes when
> a restricted view of the filesystem needs to think it's root?
> 
> e.g. VMs that mount host filesystems, remote filesystems etc and the
> client kernel tries to set a trusted. or security. xattr and you want
> to store that on an underlying normal filesystem, but your
> VM system doesn't want to have CAP_SYS_ADMIN and/or doesn't want to
> interfere with the real hosts security.
> 
> I can see some existing examples:
> 
>   9p in qemu
>      maps system.posix_acl_* to user.virtfs.system.posix_acl_*
>           stops the guest accessing any user.virtfs.*
> 
>    overlayfs
>       uses trusted.overlay.* on upper layer and blocks that from 
>            clients
> 
>    fuse-overlayfs
>       uses trusted.overlay.* for compatibiltiy if it has perms,
>       otherwise falls back to user.fuseoverlayfs.*
> 
>    crosvm's virtiofs
>       maps "security.sehash" to "user.virtiofs.security.sehash"
>       and blocks the guest from accessing user.virtiofs.*
> 
> Does anyone know of any others?
> 

Hi Dave,

Sorry, I'm not aware of any other example.

Cc'ing Christian Schoenebeck, the new 9p maintainer in QEMU in case
he has some information to share in this area.

Cheers,

--
Greg

> It all seems quite adhoc;  these all fall to bits when you
> stack them or when you write a filesystem using one of these
> schemes and then mount it with another.
> 
> (I'm about to do a similar mapping for virtiofs's C daemon)
> 
> Thanks in advance,
> 
> Dave 
> 
> --
> Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK
> 


  reply	other threads:[~2020-07-28 14:27 UTC|newest]

Thread overview: 62+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-28 10:55 Dr. David Alan Gilbert
2020-07-28 13:08 ` Greg Kurz [this message]
2020-07-28 13:55   ` Christian Schoenebeck
2020-08-04 11:28     ` Dr. David Alan Gilbert
2020-08-04 13:51       ` Christian Schoenebeck
2020-08-12 11:18         ` Dr. David Alan Gilbert
2020-08-12 13:34           ` Christian Schoenebeck
2020-08-12 14:33             ` Dr. David Alan Gilbert
2020-08-13  9:01               ` Christian Schoenebeck
2020-08-16 22:56                 ` Dave Chinner
2020-08-16 23:09                   ` Matthew Wilcox
2020-08-17  0:29                     ` Dave Chinner
2020-08-17 10:37                       ` file forks vs. xattr (was: xattr names for unprivileged stacking?) Christian Schoenebeck
2020-08-23 23:40                         ` Dave Chinner
2020-08-24 15:30                           ` Christian Schoenebeck
2020-08-24 20:01                             ` Miklos Szeredi
2020-08-24 21:26                             ` Frank van der Linden
2020-08-24 22:29                             ` Theodore Y. Ts'o
2020-08-25 15:12                               ` Christian Schoenebeck
2020-08-25 15:32                                 ` Miklos Szeredi
2020-08-27 12:02                                   ` Christian Schoenebeck
2020-08-27 12:25                                     ` Matthew Wilcox
2020-08-27 13:48                                       ` Christian Schoenebeck
2020-08-27 14:01                                         ` Matthew Wilcox
2020-08-27 14:23                                           ` Christian Schoenebeck
2020-08-27 14:25                                             ` Matthew Wilcox
2020-08-27 14:44                                             ` Al Viro
2020-08-27 16:29                                               ` Dr. David Alan Gilbert
2020-08-27 16:35                                                 ` Matthew Wilcox
2020-08-28  9:11                                                 ` Christian Schoenebeck
2020-08-28 14:46                                                   ` Theodore Y. Ts'o
2020-08-27 15:22                       ` xattr names for unprivileged stacking? Matthew Wilcox
2020-08-27 22:24                         ` Dave Chinner
2020-08-29 16:07                           ` Matthew Wilcox
2020-08-29 16:13                             ` Al Viro
2020-08-29 17:51                               ` Miklos Szeredi
2020-08-29 18:04                                 ` Al Viro
2020-08-29 18:22                                   ` Christian Schoenebeck
2020-08-29 19:13                                   ` Miklos Szeredi
2020-08-29 19:25                                     ` Al Viro
2020-08-30 19:05                                       ` Miklos Szeredi
2020-08-30 19:10                                         ` Matthew Wilcox
2020-08-31  7:34                                           ` Miklos Szeredi
2020-08-31 11:37                                             ` Matthew Wilcox
2020-08-31 11:51                                               ` Miklos Szeredi
2020-08-31 13:23                                                 ` Matthew Wilcox
2020-08-31 14:21                                                   ` Miklos Szeredi
2020-08-31 14:25                                                   ` Theodore Y. Ts'o
2020-08-31 14:45                                                     ` Matthew Wilcox
2020-08-31 14:49                                                       ` Miklos Szeredi
2020-09-01  3:34                                                     ` Dave Chinner
2020-09-01 14:52                                                       ` Theodore Y. Ts'o
2020-09-01 15:14                                                         ` Theodore Y. Ts'o
2020-09-02  5:19                                                           ` Dave Chinner
2020-08-31 18:02                                                   ` Andreas Dilger
2020-09-01  3:48                                                     ` Dave Chinner
2020-08-29 19:17                               ` Matthew Wilcox
2020-08-29 19:40                                 ` Al Viro
2020-08-29 20:12                                   ` Matthew Wilcox
2020-08-31 14:23                                     ` Theodore Y. Ts'o
2020-08-31 14:40                                       ` Matthew Wilcox
2020-08-31 16:11                                       ` Christian Schoenebeck

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