From: ebiederm@xmission.com (Eric W. Biederman)
To: Peter Hurley <peter@hurleysoftware.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: Sat, 19 Dec 2015 22:11:50 -0600 [thread overview]
Message-ID: <87a8p54v3t.fsf@x220.int.ebiederm.org> (raw)
In-Reply-To: <87y4cq6t1j.fsf@x220.int.ebiederm.org> (Eric W. Biederman's message of "Sat, 19 Dec 2015 15:13:28 -0600")
ebiederm@xmission.com (Eric W. Biederman) writes:
>>> 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)?
>
> I do not believe a fixed association with the first mount is an
> acceptable solution for implementing /dev/ptmx in association with
> a change to cause mount of devpts to be an independent filesystem.
> Such an association fails to be backwards compatible with existing
> userspace, and it is extremely fragile.
Ugh. After reviewing the userspace code that mounts devpts we have
to do use a magic /dev/ptmx to solve the issue we are trying to solve.
The fragility of detecting the primary system devpts seems solvable.
CentOS5 and openwrt-15.05 mount devpts, unmount devpts,
then mount devpts again. So a rule of mouting the internal devpts if it
isn't mounted would work for those.
CentOS6 uses switch_root and moves it's early mount of devpts onto the
primary root, and then because devpts is also in /etc/fstab tries and
fails to mount devpts once more at the same location. Implying
newinstance will make that mounting devpts twice. That sounds solvable
but I don't see a clean way of detecting that case yet.
Ugh.
I am going to pound my head up against what is needed to find the
primary system mount of devpts for a bit more and see if I can solve
that. Otherwise this exercise is pointless.
Eric
next prev parent reply other threads:[~2015-12-20 4:21 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
2015-12-14 19:55 ` H. Peter Anvin
2015-12-19 21:13 ` Eric W. Biederman
2015-12-20 4:11 ` Eric W. Biederman [this message]
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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