From: Al Viro <viro@zeniv.linux.org.uk>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: David Laight <David.Laight@aculab.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
"Eric W. Biederman" <ebiederm@xmission.com>,
"Serge E. Hallyn" <serge@hallyn.com>
Subject: Re: [PATCH 3/4] proc: Point /proc/net at /proc/thread-self/net instead of /proc/self/net
Date: Thu, 29 Sep 2022 20:34:52 +0100 [thread overview]
Message-ID: <YzXzXNAgcJeJ3M0d@ZenIV> (raw)
In-Reply-To: <CAHk-=wjLgM06JrS21W4g2VquqCLab+qu_My67cv6xuH7NhgHpw@mail.gmail.com>
On Thu, Sep 29, 2022 at 12:05:32PM -0700, Linus Torvalds wrote:
> On Thu, Sep 29, 2022 at 12:00 PM Al Viro <viro@zeniv.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?
Apparmor takes mount+dentry and turns that into pathname. Then acts
upon the resulting string. *AFTER* the original had been resolved.
IOW, it doesn't see the symlink contents - only the location where the
entire thing ends up.
AFAICS, the only way to make it STFU is either
* fix the idiotic policy
or
* make the per-thread directory show up as /proc/<something>/net
As in "../.. from there lands you in /proc". Because that's what
apparmor does to generate the string it treats as the pathname...
next prev parent reply other threads:[~2022-09-29 19:35 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-29 15:22 [PATCH 3/4] proc: Point /proc/net at /proc/thread-self/net instead of /proc/self/net David Laight
2022-09-29 18:21 ` Linus Torvalds
2022-09-29 18:50 ` Al Viro
2022-09-29 19:00 ` Al Viro
2022-09-29 19:05 ` Linus Torvalds
2022-09-29 19:34 ` Al Viro [this message]
2022-09-29 21:13 ` Linus Torvalds
2022-09-29 21:21 ` Al Viro
2022-09-29 21:27 ` Al Viro
2022-09-29 21:31 ` Linus Torvalds
2022-09-29 21:15 ` Al Viro
2022-09-29 21:29 ` Linus Torvalds
2022-09-29 22:14 ` Eric W. Biederman
2022-09-29 22:48 ` [CFT][PATCH] proc: Update /proc/net to point at the accessing threads network namespace Eric W. Biederman
2022-09-29 23:38 ` Al Viro
2022-09-30 3:19 ` kernel test robot
2022-09-30 6:07 ` kernel test robot
2022-09-30 9:30 ` David Laight
2022-09-30 16:17 ` Eric W. Biederman
2022-09-30 21:28 ` David Laight
2022-10-01 23:11 ` Al Viro
2022-10-03 9:36 ` David Laight
2022-10-03 14:03 ` Al Viro
2022-10-03 17:07 ` Eric W. Biederman
2022-10-03 18:49 ` Al Viro
2022-10-04 8:53 ` David Laight
2022-10-05 13:10 ` [proc] 5336f1902b: BUG:KASAN:global-out-of-bounds_in_memchr kernel test robot
2022-09-29 19:00 ` [PATCH 3/4] proc: Point /proc/net at /proc/thread-self/net instead of /proc/self/net Linus Torvalds
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