From: Alan Jenkins <alan.christopher.jenkins@gmail.com>
To: David Howells <dhowells@redhat.com>
Cc: viro@zeniv.linux.org.uk, linux-api@vger.kernel.org,
torvalds@linux-foundation.org, linux-fsdevel@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 01/33] vfs: syscall: Add open_tree(2) to reference or clone a mount [ver #11]
Date: Fri, 3 Aug 2018 00:46:14 +0100 [thread overview]
Message-ID: <c50af5da-2168-b35a-0d28-5af887cd997a@gmail.com> (raw)
In-Reply-To: <21311.1533246718@warthog.procyon.org.uk>
On 02/08/18 22:51, David Howells wrote:
> Alan Jenkins <alan.christopher.jenkins@gmail.com> wrote:
>
>> Another closely-related limitation of `mount`, is that it can't atomically set
>> the propagation type at mount time.
> I want to add a mount_setattr() too at some point:
>
> fd = open_tree(..., OPEN_TREE_CLONE);
> mount_setattr(fd, ...);
> move_mount(fd, ...);
Cool. Not having to mess with fchdir() sounds nice. (And as a bonus,
being able to avoid the existing multiplexed mount() call, which looks
ugly from all the NULL arguments if nothing else).
> I'm not sure whether you should be able to fchdir into the cloned tree since
> it isn't attached to any mount namespace.
>
> David
I don't see a check prohibiting it :-). I don't think it's a problem.
You can already chdir/chroot into a different mount namespace, you just
can't do any mount operations on it. (You said you want to be able to,
but so far move_mount() still prohibits it, I guess that's for the future).
And you can already do the same into a mount that has been detached,
which will have `mount->mnt_ns = NULL` if I'm reading correctly.
Hmm, there is something that's been nagging at me though. I'm
suspicious about what happens in this series, when you move_mount() from
a victim of MNT_DETACH. I think umount2(MNT_DETACH) sets a flag
MNT_UMOUNT. It's a flag that was added to help correctly handle
MNT_LOCKED in the face of umount2(MNT_DETACH). It's also the point
where my understanding of the kernel mount/unmount code breaks down
:-). But it seems to override both IS_MNT_LOCKED() and UMOUNT_CONNECTED
in disconnect_mount(). That would give another chance to defeat locked
mounts.
Regards
Alan
next prev parent reply other threads:[~2018-08-02 23:46 UTC|newest]
Thread overview: 222+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-08-01 15:23 [PATCH 00/33] VFS: Introduce filesystem context [ver #11] David Howells
2018-08-01 15:23 ` David Howells
2018-08-01 15:23 ` David Howells
2018-08-01 15:24 ` [PATCH 01/33] vfs: syscall: Add open_tree(2) to reference or clone a mount " David Howells
2018-08-02 17:31 ` Alan Jenkins
2018-08-02 21:29 ` Al Viro
2018-08-02 21:29 ` Al Viro
2018-08-02 21:51 ` David Howells
2018-08-02 23:46 ` Alan Jenkins [this message]
2018-08-01 15:24 ` [PATCH 02/33] vfs: syscall: Add move_mount(2) to move mounts around " David Howells
2018-08-01 15:24 ` [PATCH 03/33] teach move_mount(2) to work with OPEN_TREE_CLONE " David Howells
2018-10-12 14:25 ` Alan Jenkins
2018-08-01 15:24 ` [PATCH 04/33] vfs: Suppress MS_* flag defs within the kernel unless explicitly enabled " David Howells
2018-08-01 15:24 ` [PATCH 05/33] vfs: Introduce the basic header for the new mount API's filesystem context " David Howells
2018-08-01 15:24 ` [PATCH 06/33] vfs: Introduce logging functions " David Howells
2018-08-01 15:24 ` [PATCH 07/33] vfs: Add configuration parser helpers " David Howells
2018-08-01 15:24 ` [PATCH 08/33] vfs: Add LSM hooks for the new mount API " David Howells
2018-08-01 15:24 ` David Howells
2018-08-01 20:50 ` James Morris
2018-08-01 20:50 ` James Morris
2018-08-01 22:53 ` David Howells
2018-08-01 22:53 ` David Howells
2018-08-01 15:25 ` [PATCH 09/33] selinux: Implement the new mount API LSM hooks " David Howells
2018-08-01 15:25 ` David Howells
2018-08-01 15:25 ` [PATCH 10/33] smack: Implement filesystem context security " David Howells
2018-08-01 15:25 ` David Howells
2018-08-01 15:25 ` [PATCH 11/33] apparmor: Implement security hooks for the new mount API " David Howells
2018-08-01 15:25 ` David Howells
2018-08-01 15:25 ` [PATCH 12/33] tomoyo: " David Howells
2018-08-01 15:25 ` David Howells
2018-08-01 15:25 ` [PATCH 13/33] vfs: Separate changing mount flags full remount " David Howells
2018-08-01 15:25 ` [PATCH 14/33] vfs: Implement a filesystem superblock creation/configuration context " David Howells
2018-09-11 17:46 ` Guenter Roeck
2018-09-11 21:52 ` David Howells
2018-09-11 22:07 ` Guenter Roeck
2018-09-11 23:17 ` David Howells
2018-09-11 23:54 ` Guenter Roeck
2018-09-18 9:07 ` Sergey Senozhatsky
2018-09-18 9:40 ` Sergey Senozhatsky
2018-09-18 14:06 ` Guenter Roeck
2018-09-19 1:12 ` Sergey Senozhatsky
2018-09-19 1:26 ` Sergey Senozhatsky
2018-09-18 15:34 ` David Howells
2018-09-18 16:39 ` David Howells
2018-09-19 1:15 ` Sergey Senozhatsky
2018-09-18 17:43 ` David Howells
2018-09-18 9:54 ` Sergey Senozhatsky
2018-09-18 15:28 ` David Howells
2018-08-01 15:25 ` [PATCH 15/33] vfs: Remove unused code after filesystem context changes " David Howells
2018-08-01 15:25 ` [PATCH 16/33] procfs: Move proc_fill_super() to fs/proc/root.c " David Howells
2018-08-01 15:26 ` [PATCH 17/33] proc: Add fs_context support to procfs " David Howells
2018-08-01 15:26 ` [PATCH 18/33] ipc: Convert mqueue fs to fs_context " David Howells
2018-08-01 15:26 ` [PATCH 19/33] cpuset: Use " David Howells
2018-08-01 15:26 ` [PATCH 20/33] kernfs, sysfs, cgroup, intel_rdt: Support " David Howells
2018-08-01 15:26 ` [PATCH 21/33] hugetlbfs: Convert to " David Howells
2018-08-01 15:26 ` [PATCH 22/33] vfs: Remove kern_mount_data() " David Howells
2018-08-01 15:26 ` [PATCH 23/33] vfs: Provide documentation for new mount API " David Howells
2018-08-01 15:26 ` [PATCH 24/33] Make anon_inodes unconditional " David Howells
2018-08-01 15:26 ` [PATCH 25/33] vfs: syscall: Add fsopen() to prepare for superblock creation " David Howells
2018-08-01 15:27 ` [PATCH 26/33] vfs: Implement logging through fs_context " David Howells
2018-08-01 15:27 ` [PATCH 27/33] vfs: Add some logging to the core users of the fs_context log " David Howells
2018-08-01 15:27 ` [PATCH 28/33] vfs: syscall: Add fsconfig() for configuring and managing a context " David Howells
2018-08-06 17:28 ` Eric W. Biederman
2018-08-09 14:14 ` David Howells
2018-08-09 14:14 ` David Howells
2018-08-09 14:24 ` David Howells
2018-08-09 14:24 ` David Howells
2018-08-09 14:35 ` Miklos Szeredi
2018-08-09 15:32 ` Eric W. Biederman
2018-08-09 16:33 ` David Howells
2018-08-11 20:20 ` David Howells
2018-08-11 23:26 ` Andy Lutomirski
2018-08-01 15:27 ` [PATCH 29/33] vfs: syscall: Add fsmount() to create a mount for a superblock " David Howells
2018-08-01 15:27 ` [PATCH 30/33] vfs: syscall: Add fspick() to select a superblock for reconfiguration " David Howells
2018-08-24 14:51 ` Miklos Szeredi
2018-08-24 14:54 ` Andy Lutomirski
2018-08-01 15:27 ` [PATCH 31/33] afs: Add fs_context support " David Howells
2018-08-01 15:27 ` [PATCH 32/33] afs: Use fs_context to pass parameters over automount " David Howells
2018-08-01 15:27 ` [PATCH 33/33] vfs: Add a sample program for the new mount API " David Howells
2018-08-10 14:05 ` BUG: Mount ignores mount options Eric W. Biederman
2018-08-10 14:05 ` Eric W. Biederman
2018-08-10 14:05 ` Eric W. Biederman
2018-08-10 14:36 ` Andy Lutomirski
2018-08-10 14:36 ` Andy Lutomirski
2018-08-10 14:36 ` Andy Lutomirski
2018-08-10 15:17 ` Eric W. Biederman
2018-08-10 15:17 ` Eric W. Biederman
2018-08-10 15:17 ` Eric W. Biederman
2018-08-10 15:24 ` Al Viro
2018-08-10 15:24 ` Al Viro
2018-08-10 15:24 ` Al Viro
2018-08-10 15:11 ` Tetsuo Handa
2018-08-10 15:11 ` Tetsuo Handa
2018-08-10 15:13 ` David Howells
2018-08-10 15:13 ` David Howells
2018-08-10 15:13 ` David Howells
2018-08-10 15:16 ` Al Viro
2018-08-10 15:16 ` Al Viro
2018-08-10 15:16 ` Al Viro
2018-08-11 1:05 ` Eric W. Biederman
2018-08-11 1:05 ` Eric W. Biederman
2018-08-11 1:05 ` Eric W. Biederman
2018-08-11 1:46 ` Theodore Y. Ts'o
2018-08-11 1:46 ` Theodore Y. Ts'o
2018-08-11 1:46 ` Theodore Y. Ts'o
2018-08-11 4:48 ` Eric W. Biederman
2018-08-11 4:48 ` Eric W. Biederman
2018-08-11 4:48 ` Eric W. Biederman
2018-08-11 17:47 ` Casey Schaufler
2018-08-11 17:47 ` Casey Schaufler
2018-08-11 17:47 ` Casey Schaufler
2018-08-15 4:03 ` Eric W. Biederman
2018-08-15 4:03 ` Eric W. Biederman
2018-08-15 4:03 ` Eric W. Biederman
2018-08-11 1:58 ` Al Viro
2018-08-11 1:58 ` Al Viro
2018-08-11 1:58 ` Al Viro
2018-08-11 2:17 ` Al Viro
2018-08-11 2:17 ` Al Viro
2018-08-11 2:17 ` Al Viro
2018-08-11 4:43 ` Eric W. Biederman
2018-08-11 4:43 ` Eric W. Biederman
2018-08-11 4:43 ` Eric W. Biederman
2018-08-13 12:54 ` Miklos Szeredi
2018-08-13 12:54 ` Miklos Szeredi
2018-08-13 12:54 ` Miklos Szeredi
2018-08-10 15:11 ` David Howells
2018-08-10 15:11 ` David Howells
2018-08-10 15:11 ` David Howells
2018-08-10 15:39 ` Theodore Y. Ts'o
2018-08-10 15:39 ` Theodore Y. Ts'o
2018-08-10 15:39 ` Theodore Y. Ts'o
2018-08-10 15:39 ` Theodore Y. Ts'o
2018-08-10 15:55 ` Casey Schaufler
2018-08-10 15:55 ` Casey Schaufler
2018-08-10 15:55 ` Casey Schaufler
2018-08-10 15:55 ` Casey Schaufler
2018-08-10 16:11 ` David Howells
2018-08-10 16:11 ` David Howells
2018-08-10 16:11 ` David Howells
2018-08-10 18:00 ` Eric W. Biederman
2018-08-10 18:00 ` Eric W. Biederman
2018-08-10 15:53 ` David Howells
2018-08-10 15:53 ` David Howells
2018-08-10 15:53 ` David Howells
2018-08-10 16:14 ` Theodore Y. Ts'o
2018-08-10 16:14 ` Theodore Y. Ts'o
2018-08-10 16:14 ` Theodore Y. Ts'o
2018-08-10 16:14 ` Theodore Y. Ts'o
2018-08-10 20:06 ` Andy Lutomirski
2018-08-10 20:06 ` Andy Lutomirski
2018-08-10 20:06 ` Andy Lutomirski
2018-08-10 20:46 ` Theodore Y. Ts'o
2018-08-10 20:46 ` Theodore Y. Ts'o
2018-08-10 20:46 ` Theodore Y. Ts'o
2018-08-10 22:12 ` Darrick J. Wong
2018-08-10 22:12 ` Darrick J. Wong
2018-08-10 22:12 ` Darrick J. Wong
2018-08-10 23:54 ` Theodore Y. Ts'o
2018-08-10 23:54 ` Theodore Y. Ts'o
2018-08-10 23:54 ` Theodore Y. Ts'o
2018-08-10 23:54 ` Theodore Y. Ts'o
2018-08-11 0:38 ` Darrick J. Wong
2018-08-11 0:38 ` Darrick J. Wong
2018-08-11 0:38 ` Darrick J. Wong
2018-08-11 0:38 ` Darrick J. Wong
2018-08-11 1:32 ` Eric W. Biederman
2018-08-11 1:32 ` Eric W. Biederman
2018-08-11 1:32 ` Eric W. Biederman
2018-08-13 16:35 ` Alan Cox
2018-08-13 16:35 ` Alan Cox
2018-08-13 16:35 ` Alan Cox
2018-08-13 16:48 ` Andy Lutomirski
2018-08-13 16:48 ` Andy Lutomirski
2018-08-13 16:48 ` Andy Lutomirski
2018-08-13 17:29 ` Al Viro
2018-08-13 17:29 ` Al Viro
2018-08-13 17:29 ` Al Viro
2018-08-13 19:00 ` James Morris
2018-08-13 19:00 ` James Morris
2018-08-13 19:00 ` James Morris
2018-08-13 19:20 ` Casey Schaufler
2018-08-13 19:20 ` Casey Schaufler
2018-08-13 19:20 ` Casey Schaufler
2018-08-15 23:29 ` Serge E. Hallyn
2018-08-15 23:29 ` Serge E. Hallyn
2018-08-15 23:29 ` Serge E. Hallyn
2018-08-11 0:28 ` Eric W. Biederman
2018-08-11 0:28 ` Eric W. Biederman
2018-08-11 0:28 ` Eric W. Biederman
2018-08-11 1:19 ` Eric W. Biederman
2018-08-11 1:19 ` Eric W. Biederman
2018-08-11 1:19 ` Eric W. Biederman
2018-08-11 7:29 ` David Howells
2018-08-11 7:29 ` David Howells
2018-08-11 7:29 ` David Howells
2018-08-11 16:31 ` Andy Lutomirski
2018-08-11 16:31 ` Andy Lutomirski
2018-08-11 16:31 ` Andy Lutomirski
2018-08-11 16:51 ` Al Viro
2018-08-11 16:51 ` Al Viro
2018-08-11 16:51 ` Al Viro
2018-08-15 16:31 ` Should we split the network filesystem setup into two phases? David Howells
2018-08-15 16:31 ` David Howells
2018-08-15 16:51 ` Andy Lutomirski
2018-08-15 16:51 ` Andy Lutomirski
2018-08-15 16:51 ` Andy Lutomirski
2018-08-16 3:51 ` Steve French
2018-08-16 3:51 ` Steve French
2018-08-16 5:06 ` Eric W. Biederman
2018-08-16 5:06 ` Eric W. Biederman
2018-08-16 16:24 ` Steve French
2018-08-16 16:24 ` Steve French
2018-08-16 17:21 ` Eric W. Biederman
2018-08-16 17:21 ` Eric W. Biederman
2018-08-16 17:23 ` Aurélien Aptel
2018-08-16 17:23 ` Aurélien Aptel
2018-08-16 18:36 ` Steve French
2018-08-16 18:36 ` Steve French
2018-08-16 18:36 ` Steve French
2018-08-17 23:11 ` Al Viro
2018-08-17 23:11 ` Al Viro
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