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From: Peter Hurley <peter@hurleysoftware.com>
To: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Greg KH <greg@kroah.com>, Jiri Slaby <jslaby@suse.com>,
	"H. Peter Anvin" <hpa@zytor.com>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Aurelien Jarno <aurelien@aurel32.net>,
	Andy Lutomirski <luto@amacapital.net>,
	Florian Weimer <fw@deneb.enyo.de>,
	Al Viro <viro@zeniv.linux.org.uk>,
	Serge Hallyn <serge.hallyn@ubuntu.com>,
	Jann Horn <jann@thejh.net>,
	"security@kernel.org" <security@kernel.org>,
	"security@ubuntu.com >> security" <security@ubuntu.com>,
	security@debian.org, Willy Tarreau <w@1wt.eu>,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH] devpts: Sensible /dev/ptmx & force newinstance
Date: Mon, 14 Dec 2015 11:47:35 -0800	[thread overview]
Message-ID: <566F1CD7.20502@hurleysoftware.com> (raw)
In-Reply-To: <87wpskyds7.fsf_-_@x220.int.ebiederm.org>

On 12/11/2015 11:40 AM, Eric W. Biederman wrote:
> Forcing newinstance for every mount of the devpts filesystem actually
> requires the association between /dev/ptmx and the currently mounted
> instance of devpts at /dev/pts.  Simply remembering the first mount of
> the devpts filesystem and associating that with /dev/ptmx is not
> enough.  I am aware of at least one instance where an initramfs mounts
> devpts before the main system instance of devpts is mounted.

Can you point me to that usage please?

I ask because there's a patch to move devpts init from module initcall
up to fs initcall (neither devpts nor the pty driver is actually built
as a module anyway), and I'd like to look at what the consequences
might be for that userspace configuration.


> In that system ptys simply did not work after boot when I tested
> associating /dev/ptmx with the first mount of the devpts filesystem.

Assuming userspace isn't broken by that patch, is a fixed association
with first mount otherwise an acceptable solution for magic /dev/ptmx
(where /dev/ptmx is not a symlink to /dev/pts/ptmx)?

Regards,
Peter Hurley


  parent reply	other threads:[~2015-12-14 19:47 UTC|newest]

Thread overview: 154+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <43AD2BA7-B594-4299-95F3-D86FD38AF21B@zytor.com>
     [not found] ` <87egexpf4o.fsf@x220.int.ebiederm.org>
     [not found]   ` <CA+55aFw9Bg+Zh_T4zP487n3ieaxoMHgZ_nNJVdpSR4kQK9gQ9w@mail.gmail.com>
     [not found]     ` <1CB621EF-1647-463B-A144-D611DB150E15@zytor.com>
     [not found]       ` <20151208223135.GA8352@kroah.com>
     [not found]         ` <87oae0h2bo.fsf@x220.int.ebiederm.org>
     [not found]           ` <56677DE3.5040705@zytor.com>
     [not found]             ` <20151209012311.GA11794@kroah.com>
     [not found]               ` <84B136DF-55E4-476A-9CB2-062B15677EE5@zytor.com>
     [not found]                 ` <20151209013859.GA12442@kroah.com>
     [not found]                   ` <20151209083225.GA30452@1wt.eu>
2015-12-11 19:40                     ` [PATCH] devpts: Sensible /dev/ptmx & force newinstance Eric W. Biederman
2015-12-11 20:50                       ` Linus Torvalds
2015-12-11 21:03                         ` Eric W. Biederman
2015-12-11 21:04                       ` Al Viro
2015-12-11 21:11                         ` Eric W. Biederman
2015-12-11 21:48                           ` Andy Lutomirski
2015-12-11 22:07                             ` H. Peter Anvin
2015-12-11 22:12                               ` Andy Lutomirski
2015-12-11 22:18                                 ` H. Peter Anvin
2015-12-11 22:24                                   ` Andy Lutomirski
2015-12-11 22:29                                     ` H. Peter Anvin
2015-12-11 22:35                                 ` Eric W. Biederman
2015-12-11 22:52                                   ` Andy Lutomirski
2015-12-11 22:58                                     ` Jann Horn
2015-12-11 23:00                                       ` Andy Lutomirski
2015-12-11 23:07                                         ` H. Peter Anvin
2015-12-11 23:16                                           ` Andy Lutomirski
2015-12-11 23:30                                             ` H. Peter Anvin
2015-12-11 22:57                                   ` H. Peter Anvin
2015-12-14 19:47                       ` Peter Hurley [this message]
2015-12-14 19:55                         ` H. Peter Anvin
2015-12-19 21:13                         ` Eric W. Biederman
2015-12-20  4:11                           ` Eric W. Biederman
2015-12-20  4:35                             ` H. Peter Anvin
2015-12-20  9:42                               ` Eric W. Biederman
2015-12-21 22:03                                 ` Eric W. Biederman
2015-12-21 22:23                                   ` Linus Torvalds
2016-04-05  0:03                                     ` [PATCH 00/13] devpts: New instances for every mount Eric W. Biederman
2016-04-05  1:29                                       ` [PATCH 01/13] devpts: Teach /dev/ptmx to find the associated devpts via path lookup Eric W. Biederman
2016-04-05  1:29                                         ` [PATCH 02/13] devpts: More obvious check for the system devpts in pty allocation Eric W. Biederman
2016-04-05  1:29                                         ` [PATCH 03/13] devpts: Cleanup newinstance parsing Eric W. Biederman
2016-04-05  1:29                                         ` [PATCH 04/13] devpts: Stop rolling devpts_remount by hand in devpts_mount Eric W. Biederman
2016-04-05  1:29                                         ` [PATCH 05/13] devpts: Fail early (if appropriate) on overmount Eric W. Biederman
2016-04-05  1:29                                         ` [PATCH 06/13] devpts: Use the same default mode for both /dev/ptmx and dev/pts/ptmx Eric W. Biederman
2016-04-05  1:29                                         ` [PATCH 07/13] devpts: Move parse_mount_options into fill_super Eric W. Biederman
2016-04-05  1:29                                         ` [PATCH 08/13] devpts: Make devpts_kill_sb safe if fsi is NULL Eric W. Biederman
2016-04-05  1:29                                         ` [PATCH 09/13] devpts: Move the creation of /dev/pts/ptmx into fill_super Eric W. Biederman
2016-04-05  1:29                                         ` [PATCH 10/13] devpts: Simplify devpts_mount by using mount_nodev Eric W. Biederman
2016-04-05  1:29                                         ` [PATCH 11/13] vfs: Implement mount_super_once Eric W. Biederman
2016-04-05  1:29                                         ` [PATCH 12/13] devpts: Always return a distinct instance when mounting Eric W. Biederman
2016-04-05  1:29                                         ` [PATCH 13/13] devpts: Kill the DEVPTS_MULTIPLE_INSTANCE config option Eric W. Biederman
2016-04-05  2:54                                         ` [PATCH 01/13] devpts: Teach /dev/ptmx to find the associated devpts via path lookup Al Viro
2016-04-05  3:03                                           ` Al Viro
2016-04-08 18:54                                             ` Eric W. Biederman
2016-04-07 16:06                                         ` Linus Torvalds
2016-04-08 18:51                                           ` Eric W. Biederman
2016-04-08 19:05                                             ` Linus Torvalds
2016-04-08 20:05                                               ` Eric W. Biederman
2016-04-08 20:43                                               ` Andy Lutomirski
2016-04-08 21:29                                                 ` Eric W. Biederman
2016-04-08 21:54                                                   ` Linus Torvalds
2016-04-08 23:03                                                     ` Eric W. Biederman
2016-04-08 21:56                                                   ` Andy Lutomirski
2016-04-09 13:09                                             ` One Thousand Gnomes
2016-04-09 14:10                                               ` H. Peter Anvin
2016-04-09 14:45                                                 ` Eric W. Biederman
2016-04-09 22:37                                                   ` H. Peter Anvin
2016-04-10  0:01                                                     ` Linus Torvalds
2016-04-10  0:06                                                       ` H. Peter Anvin
2016-04-10  0:16                                                         ` Linus Torvalds
2016-04-10  0:44                                                           ` Andy Lutomirski
     [not found]                                                             ` <CA+55aFzs00iDkYhvFCq=AZMVcNL0+oZT4SeimTeVurJq=5ZS3A@mail.gmail.com>
2016-04-11 14:48                                                               ` H. Peter Anvin
2016-04-12  1:31                                                                 ` Al Viro
2016-04-11 20:12                                                               ` Andy Lutomirski
2016-04-11 20:10                                                                 ` Eric W. Biederman
2016-04-11 20:16                                                                 ` H. Peter Anvin
2016-04-11 23:37                                                                   ` Eric W. Biederman
2016-04-12  0:01                                                                     ` Linus Torvalds
2016-04-12  0:10                                                                       ` Eric W. Biederman
2016-04-12  1:06                                                                         ` H. Peter Anvin
2016-04-12  1:18                                                                           ` Linus Torvalds
2016-04-12  1:23                                                                           ` Eric W. Biederman
2016-04-12  1:47                                                                             ` Al Viro
2016-04-12  1:34                                                                         ` Al Viro
2016-04-12  2:16                                                                           ` Eric W. Biederman
2016-04-12 17:44                                                                 ` Andy Lutomirski
2016-04-12 18:12                                                                   ` Linus Torvalds
2016-04-12 19:07                                                                     ` H. Peter Anvin
2016-04-15 15:34                                                                       ` [PATCH 01/16] devpts: Attempting to get it right Eric W. Biederman
2016-04-15 15:35                                                                         ` [PATCH 01/16] devpts: Use the same default mode for both /dev/ptmx and dev/pts/ptmx Eric W. Biederman
2016-04-15 15:35                                                                           ` [PATCH 02/16] devpts: Set the proper fops for /dev/pts/ptmx Eric W. Biederman
2016-04-15 15:35                                                                           ` [PATCH 03/16] vfs: Implement vfs_loopback_mount Eric W. Biederman
2016-04-15 15:35                                                                           ` [PATCH 04/16] devpts: Teach /dev/ptmx to automount the appropriate devpts via path lookup Eric W. Biederman
2016-04-15 22:03                                                                             ` Jann Horn
2016-04-19 18:46                                                                               ` Eric W. Biederman
2016-04-15 15:35                                                                           ` [PATCH 05/16] vfs: Allow unlink, and rename on expirable file mounts Eric W. Biederman
2016-04-15 15:35                                                                           ` [PATCH 06/16] devpts: More obvious check for the system devpts in pty allocation Eric W. Biederman
2016-04-15 15:35                                                                           ` [PATCH 07/16] devpts: Cleanup newinstance parsing Eric W. Biederman
2016-04-15 15:35                                                                           ` [PATCH 08/16] devpts: Stop rolling devpts_remount by hand in devpts_mount Eric W. Biederman
2016-04-15 15:35                                                                           ` [PATCH 09/16] devpts: Fail early (if appropriate) on overmount Eric W. Biederman
2016-04-15 15:35                                                                           ` [PATCH 10/16] devpts: Move parse_mount_options into fill_super Eric W. Biederman
2016-04-15 15:35                                                                           ` [PATCH 11/16] devpts: Make devpts_kill_sb safe if fsi is NULL Eric W. Biederman
2016-04-15 15:35                                                                           ` [PATCH 12/16] devpts: Move the creation of /dev/pts/ptmx into fill_super Eric W. Biederman
2016-04-15 15:35                                                                           ` [PATCH 13/16] devpts: Simplify devpts_mount by using mount_nodev Eric W. Biederman
2016-04-15 15:35                                                                           ` [PATCH 14/16] vfs: Implement mount_super_once Eric W. Biederman
2016-04-15 23:02                                                                             ` Linus Torvalds
2016-04-19 18:22                                                                               ` Eric W. Biederman
2016-04-19 18:47                                                                                 ` H. Peter Anvin
2016-04-19 19:03                                                                                   ` Eric W. Biederman
2016-04-19 19:25                                                                                     ` H. Peter Anvin
2016-04-19 19:26                                                                                       ` H. Peter Anvin
2016-04-20  3:27                                                                                         ` Eric W. Biederman
2016-04-20 11:50                                                                                           ` Austin S. Hemmelgarn
2016-04-20 16:12                                                                                             ` H. Peter Anvin
2016-04-19 18:55                                                                                 ` H. Peter Anvin
2016-04-19 23:29                                                                                 ` Linus Torvalds
2016-04-20  1:24                                                                                   ` Linus Torvalds
2016-04-20  1:37                                                                                     ` H. Peter Anvin
2016-04-15 15:35                                                                           ` [PATCH 15/16] devpts: Always return a distinct instance when mounting Eric W. Biederman
2016-04-15 15:35                                                                           ` [PATCH 16/16] devpts: Kill the DEVPTS_MULTIPLE_INSTANCE config option Eric W. Biederman
2016-04-15 16:49                                                                         ` [PATCH 01/16] devpts: Attempting to get it right Andy Lutomirski
2016-04-15 20:43                                                                           ` Eric W. Biederman
2016-04-15 21:29                                                                             ` H. Peter Anvin
2016-04-19 19:00                                                                               ` Eric W. Biederman
2016-04-16 18:31                                                                         ` Linus Torvalds
2016-04-19 18:44                                                                           ` Does anyone care about a race free ptsname? Eric W. Biederman
2016-04-19 19:16                                                                             ` H. Peter Anvin
2016-04-19 20:32                                                                               ` Eric W. Biederman
2016-04-19 20:55                                                                                 ` H. Peter Anvin
2016-04-19 20:42                                                                             ` Serge E. Hallyn
2016-04-19 23:23                                                                             ` Linus Torvalds
2016-04-19 23:39                                                                               ` H. Peter Anvin
2016-04-20  0:18                                                                                 ` Linus Torvalds
2016-04-20  1:48                                                                                 ` Serge E. Hallyn
2016-04-19 22:06                                                                           ` [PATCH 01/16] devpts: Attempting to get it right Eric W. Biederman
2016-04-19 23:35                                                                             ` Linus Torvalds
2016-04-20  0:24                                                                               ` Peter Hurley
2016-04-20  0:49                                                                                 ` Peter Hurley
2016-04-20  3:04                                                                               ` [PATCH] devpts: Make each mount of devpts an independent filesystem Eric W. Biederman
2016-04-20  3:25                                                                                 ` Al Viro
2016-04-20  3:43                                                                                   ` Eric W. Biederman
2016-04-20  4:11                                                                                     ` Al Viro
2016-04-20  4:21                                                                                       ` Eric W. Biederman
2016-04-20  4:36                                                                                 ` Konstantin Khlebnikov
2016-04-20  4:49                                                                                   ` Linus Torvalds
2016-04-20 14:55                                                                                     ` Eric W. Biederman
2016-04-20 15:34                                                                                       ` Konstantin Khlebnikov
2016-04-20 15:50                                                                                         ` Eric W. Biederman
2016-04-20 17:00                                                                                         ` [PATCH v2] " Eric W. Biederman
     [not found]                                                                                           ` <874mabt3df.fsf_-_@x220.int.ebiederm.org>
2016-05-06 19:04                                                                                             ` [PATCH 1/1] " Eric W. Biederman
2016-05-06 19:35                                                                                             ` [PATCH 0/1] devpts: Removing the need for pt_chown Greg KH
2016-05-06 19:45                                                                                               ` Peter Hurley
2016-05-06 19:54                                                                                                 ` Greg KH
2016-06-02 15:29                                                                                                   ` [PATCH tty-next] devpts: Make each mount of devpts an independent filesystem Eric W. Biederman
2016-06-02 18:57                                                                                                     ` Linus Torvalds
2016-06-02 20:22                                                                                                       ` Eric W. Biederman
2016-06-02 20:36                                                                                                         ` H. Peter Anvin
2016-06-02 21:23                                                                                                           ` Eric W. Biederman
2016-06-02 21:44                                                                                                             ` Linus Torvalds
2016-04-11 23:49                                                               ` [PATCH 01/13] devpts: Teach /dev/ptmx to find the associated devpts via path lookup Eric W. Biederman
2016-04-12  0:08                                                                 ` Linus Torvalds
2016-04-12  0:22                                                                   ` Eric W. Biederman
2016-04-12  0:50                                                                     ` Linus Torvalds
2016-04-11 20:05                                                       ` Eric W. Biederman

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