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Subject: Re: [PATCH 01/13] devpts: Teach /dev/ptmx to find the associated devpts via path lookup
From: "H. Peter Anvin" <hpa@zytor.com>
Date: Mon, 11 Apr 2016 07:48:28 -0700
To: Linus Torvalds <torvalds@linux-foundation.org>,
        Andy Lutomirski <luto@amacapital.net>
CC: security@debian.org, security@kernel.org,
        Al Viro <viro@zeniv.linux.org.uk>,
        "security@ubuntu.com >> security" <security@ubuntu.com>,
        Peter Hurley <peter@hurleysoftware.com>,
        "Eric W. Biederman" <ebiederm@xmission.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>
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On April 9, 2016 6:27:36 PM PDT, Linus Torvalds <torvalds@linux-foundation.org> wrote:
>On Apr 9, 2016 5:45 PM, "Andy Lutomirski" <luto@amacapital.net> wrote:
>>
>>
>> What we *do* want to do, though, is to prevent the following:
>
>I don't see the point. Why do you bring up this insane scenario that
>nobody
>can possibly care about?
>
>So you actually have any reason to believe somebody does that?
>
>I already asked about that earlier, and the silence was deafening.
>
>    Linus

Here is an entire different approach, I don't know if it is sane or not: when *mounting* the devpts filesystem, it could automagically create the bins mount for ptmx in the parent of its mount point.  Presumably the would be a mount option to disable that behavior.

Does anyone see an obvious problem with that?
-- 
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