linux-kernel - Re: [PATCH 3/4] proc: Point /proc/net at /proc/thread-self/net instead of /proc/self/net

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Message-ID: <CAHk-=wjLgM06JrS21W4g2VquqCLab+qu_My67cv6xuH7NhgHpw@mail.gmail.com>
Date:   Thu, 29 Sep 2022 12:05:32 -0700
From:   Linus Torvalds <torvalds@...ux-foundation.org>
To:     Al Viro <viro@...iv.linux.org.uk>
Cc:     David Laight <David.Laight@...lab.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "Eric W. Biederman" <ebiederm@...ssion.com>,
        "Serge E. Hallyn" <serge@...lyn.com>
Subject: Re: [PATCH 3/4] proc: Point /proc/net at /proc/thread-self/net
 instead of /proc/self/net

On Thu, Sep 29, 2022 at 12:00 PM Al Viro <viro@...iv.linux.org.uk> wrote:
>
> Which is insane, especially since the entire problem is due to wanting
> that directory to be different for different threads...

Absolutely. This is all due to Apparmor (a) basing things on pathnames
and (b) then getting those pathnames wrong.

Which is why I'm just suggesting we short-circuit the path-name part,
and not make this be a real symlink that actually walks a real path.

The proc <pid> handling uses "readlink" to make it *look* like a
symlink, but then "get_link" to actually look it up (and never walk it
as a path).

Something similar?

                 Linus