From: "H. Peter Anvin" <hpa@zytor.com>
To: ebiederm@xmission.com, Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>,
security@debian.org, "security@kernel.org" <security@kernel.org>,
Al Viro <viro@zeniv.linux.org.uk>,
"security@ubuntu.com >> security" <security@ubuntu.com>,
Peter Hurley <peter@hurleysoftware.com>,
Serge Hallyn <serge.hallyn@ubuntu.com>, Willy Tarreau <w@1wt.eu>,
Aurelien Jarno <aurelien@aurel32.net>,
One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk>,
Jann Horn <jann@thejh.net>, Greg KH <greg@kroah.com>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Jiri Slaby <jslaby@suse.com>, Florian Weimer <fw@deneb.enyo.de>
Subject: Re: [PATCH 01/13] devpts: Teach /dev/ptmx to find the associated devpts via path lookup
Date: Mon, 11 Apr 2016 18:06:48 -0700 [thread overview]
Message-ID: <61F170A6-5A56-4BF5-BFB5-FC62AB6F3612@zytor.com> (raw)
In-Reply-To: <87oa9fbsag.fsf@x220.int.ebiederm.org>
On April 11, 2016 5:10:47 PM PDT, ebiederm@xmission.com wrote:
>Linus Torvalds <torvalds@linux-foundation.org> writes:
>
>> On Mon, Apr 11, 2016 at 4:37 PM, Eric W. Biederman
>> <ebiederm@xmission.com> wrote:
>>>
>>> My practical concern if we worked through the implementation details
>>> would be how would it interact with people who bind mount
>/dev/pts/ptmx
>>> on top of /dev/ptmx. We might get some strange new errors.
>>
>> Yes, please don't let's play "clever" games. The semantics should be
>> fairly straightforward.
>
>Actually for me this is about keeping the semantics simpler, and coming
>up with a higher performance implementation.
>
>A dentry that does an automount is already well defined.
>
>Making the rule that accessing /dev/ptmx causes an automount of
>/dev/pts/ptmx on top of the device node at /dev/ptmx is really simple,
>with no special games. It also makes it more obvious to userspace what
>is going on. AKA allows userspace to know which superblock does an
>open
>ptmx master tty belongs to (and it happens in a backwards and forwards
>compatible way).
>
>My only concern is with this very minor change in semantics will
>anything care. I need to implement and test to find out.
>
>I think I see an implementation that Al won't grumble too loudly about.
>
>Anyway I am going to try this and see what I can see.
>
>Eric
Why bother with an automount? You can look up ../ptmx from the devpts get_super method and just do the bind mount once. No fuss, no muss. What's wrong with that?
--
Sent from my Android device with K-9 Mail. Please excuse brevity and formatting.
next prev parent reply other threads:[~2016-04-12 1:11 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
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 [this message]
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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