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From: Christian Brauner <christian@brauner.io>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>,
	Daniel Colascione <dancol@google.com>,
	Jann Horn <jannh@google.com>, Andrew Lutomirski <luto@kernel.org>,
	David Howells <dhowells@redhat.com>,
	"Serge E. Hallyn" <serge@hallyn.com>,
	Linux API <linux-api@vger.kernel.org>,
	Linux List Kernel Mailing <linux-kernel@vger.kernel.org>,
	Arnd Bergmann <arnd@arndb.de>,
	"Eric W. Biederman" <ebiederm@xmission.com>,
	Konstantin Khlebnikov <khlebnikov@yandex-team.ru>,
	Kees Cook <keescook@chromium.org>,
	Alexey Dobriyan <adobriyan@gmail.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Michael Kerrisk-manpages <mtk.manpages@gmail.com>,
	Jonathan Kowalski <bl0pbl33p@gmail.com>,
	"Dmitry V. Levin" <ldv@altlinux.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Oleg Nesterov <oleg@redhat.com>,
	Nagarathnam Muthusamy <nagarathnam.muthusamy@oracle.com>,
	Aleksa Sarai <cyphar@cyphar.com>,
	Al Viro <viro@zeniv.linux.org.uk>,
	Joel Fernandes <joel@joelfernandes.org>
Subject: Re: [PATCH v2 0/5] pid: add pidfd_open()
Date: Mon, 1 Apr 2019 00:33:56 +0200	[thread overview]
Message-ID: <20190331223355.vfbnnkmevl63etvv@brauner.io> (raw)
In-Reply-To: <CAHk-=wh0jgRkZiNdFD96Zpjx+_G+NVSHieAt+QgWCQBJ2A-5Aw@mail.gmail.com>

On Sun, Mar 31, 2019 at 03:16:47PM -0700, Linus Torvalds wrote:
> On Sun, Mar 31, 2019 at 3:03 PM Christian Brauner <christian@brauner.io> wrote:
> >
> > Thanks for the input. The problem Jann and I saw with this is that it
> > would be awkward to have the kernel open a file in some procfs instance,
> > since then userspace would have to specify which procfs instance the fd
> > should come from.
> 
> I would actually suggest we just make the rules be that the
> pidfd_open() always return the internal /proc entry regardless of any
> mount-point (or any "hidepid") but also suggest that exactly *because*
> it gives you visibility into the target pid, you'd basically require
> the strictest kind of control of the process you're trying to get the
> pidfd of.
> 
> Ie likely something along the lines of
> 
>         ptrace_may_access(task, PTRACE_MODE_ATTACH_REALCREDS)

I can live with that but I would like to hear what Jann thinks too if
that's ok.

Christian

WARNING: multiple messages have this Message-ID (diff)
From: Christian Brauner <christian@brauner.io>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>,
	Daniel Colascione <dancol@google.com>,
	Jann Horn <jannh@google.com>, Andrew Lutomirski <luto@kernel.org>,
	David Howells <dhowells@redhat.com>,
	"Serge E. Hallyn" <serge@hallyn.com>,
	Linux API <linux-api@vger.kernel.org>,
	Linux List Kernel Mailing <linux-kernel@vger.kernel.org>,
	Arnd Bergmann <arnd@arndb.de>,
	"Eric W. Biederman" <ebiederm@xmission.com>,
	Konstantin Khlebnikov <khlebnikov@yandex-team.ru>,
	Kees Cook <keescook@chromium.org>,
	Alexey Dobriyan <adobriyan@gmail.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Michael Kerrisk-manpages <mtk.manpages@gmail.com>,
	Jonathan Kowalski <bl0pbl33p@gmail.com>,
	"Dmitry V. Levin" <ldv@altlinux.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Oleg Nesterov <oleg@red>
Subject: Re: [PATCH v2 0/5] pid: add pidfd_open()
Date: Mon, 1 Apr 2019 00:33:56 +0200	[thread overview]
Message-ID: <20190331223355.vfbnnkmevl63etvv@brauner.io> (raw)
In-Reply-To: <CAHk-=wh0jgRkZiNdFD96Zpjx+_G+NVSHieAt+QgWCQBJ2A-5Aw@mail.gmail.com>

On Sun, Mar 31, 2019 at 03:16:47PM -0700, Linus Torvalds wrote:
> On Sun, Mar 31, 2019 at 3:03 PM Christian Brauner <christian@brauner.io> wrote:
> >
> > Thanks for the input. The problem Jann and I saw with this is that it
> > would be awkward to have the kernel open a file in some procfs instance,
> > since then userspace would have to specify which procfs instance the fd
> > should come from.
> 
> I would actually suggest we just make the rules be that the
> pidfd_open() always return the internal /proc entry regardless of any
> mount-point (or any "hidepid") but also suggest that exactly *because*
> it gives you visibility into the target pid, you'd basically require
> the strictest kind of control of the process you're trying to get the
> pidfd of.
> 
> Ie likely something along the lines of
> 
>         ptrace_may_access(task, PTRACE_MODE_ATTACH_REALCREDS)

I can live with that but I would like to hear what Jann thinks too if
that's ok.

Christian

  reply	other threads:[~2019-03-31 22:34 UTC|newest]

Thread overview: 158+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-03-29 15:54 [PATCH v2 0/5] pid: add pidfd_open() Christian Brauner
2019-03-29 15:54 ` [PATCH v2 1/5] Make anon_inodes unconditional Christian Brauner
2019-03-29 15:54 ` [PATCH v2 2/5] pid: add pidfd_open() Christian Brauner
2019-03-29 23:45   ` Jann Horn
2019-03-29 23:45     ` Jann Horn
2019-03-29 23:55     ` Christian Brauner
2019-03-29 23:55       ` Christian Brauner
2019-03-30 11:53   ` Jürg Billeter
2019-03-30 14:37     ` Christian Brauner
2019-03-30 14:51       ` Jonathan Kowalski
2019-03-30 14:51         ` Jonathan Kowalski
2019-03-29 15:54 ` [PATCH v2 3/5] signal: support pidfd_open() with pidfd_send_signal() Christian Brauner
2019-03-29 15:54 ` [PATCH v2 4/5] signal: PIDFD_SIGNAL_TID threads via pidfds Christian Brauner
2019-03-30  1:06   ` Jann Horn
2019-03-30  1:06     ` Jann Horn
2019-03-30  1:22     ` Christian Brauner
2019-03-30  1:22       ` Christian Brauner
2019-03-30  1:34       ` Christian Brauner
2019-03-30  1:34         ` Christian Brauner
2019-03-30  1:42         ` Christian Brauner
2019-03-30  1:42           ` Christian Brauner
2019-03-29 15:54 ` [PATCH v2 5/5] tests: add pidfd_open() tests Christian Brauner
2019-03-30 16:09 ` [PATCH v2 0/5] pid: add pidfd_open() Linus Torvalds
2019-03-30 16:09   ` Linus Torvalds
2019-03-30 16:11   ` Daniel Colascione
2019-03-30 16:11     ` Daniel Colascione
2019-03-30 16:16     ` Linus Torvalds
2019-03-30 16:16       ` Linus Torvalds
2019-03-30 16:18       ` Linus Torvalds
2019-03-30 16:18         ` Linus Torvalds
2019-03-31  1:07         ` Joel Fernandes
2019-03-31  1:07           ` Joel Fernandes
2019-03-31  2:34           ` Jann Horn
2019-03-31  2:34             ` Jann Horn
2019-03-31  4:08             ` Joel Fernandes
2019-03-31  4:08               ` Joel Fernandes
2019-03-31  4:46               ` Jann Horn
2019-03-31  4:46                 ` Jann Horn
2019-03-31 14:52                 ` Linus Torvalds
2019-03-31 14:52                   ` Linus Torvalds
2019-03-31 15:05                   ` Christian Brauner
2019-03-31 15:05                     ` Christian Brauner
2019-03-31 15:21                     ` Daniel Colascione
2019-03-31 15:21                       ` Daniel Colascione
2019-03-31 15:33                   ` Jonathan Kowalski
2019-03-31 15:33                     ` Jonathan Kowalski
2019-03-30 16:19   ` Christian Brauner
2019-03-30 16:19     ` Christian Brauner
2019-03-30 16:24     ` Linus Torvalds
2019-03-30 16:24       ` Linus Torvalds
2019-03-30 16:34       ` Daniel Colascione
2019-03-30 16:34         ` Daniel Colascione
2019-03-30 16:38         ` Christian Brauner
2019-03-30 16:38           ` Christian Brauner
2019-03-30 17:04         ` Linus Torvalds
2019-03-30 17:04           ` Linus Torvalds
2019-03-30 17:12           ` Christian Brauner
2019-03-30 17:12             ` Christian Brauner
2019-03-30 17:24             ` Linus Torvalds
2019-03-30 17:24               ` Linus Torvalds
2019-03-30 17:37               ` Christian Brauner
2019-03-30 17:37                 ` Christian Brauner
2019-03-30 17:50               ` Jonathan Kowalski
2019-03-30 17:50                 ` Jonathan Kowalski
2019-03-30 17:52                 ` Christian Brauner
2019-03-30 17:52                   ` Christian Brauner
2019-03-30 17:59                   ` Jonathan Kowalski
2019-03-30 17:59                     ` Jonathan Kowalski
2019-03-30 18:02                     ` Christian Brauner
2019-03-30 18:02                       ` Christian Brauner
2019-03-30 18:00               ` Jann Horn
2019-03-30 18:00                 ` Jann Horn
2019-03-31 20:09               ` Andy Lutomirski
2019-03-31 20:09                 ` Andy Lutomirski
2019-03-31 21:03                 ` Linus Torvalds
2019-03-31 21:03                   ` Linus Torvalds
2019-03-31 21:10                   ` Christian Brauner
2019-03-31 21:10                     ` Christian Brauner
2019-03-31 21:17                     ` Linus Torvalds
2019-03-31 21:17                       ` Linus Torvalds
2019-03-31 22:03                       ` Christian Brauner
2019-03-31 22:03                         ` Christian Brauner
2019-03-31 22:16                         ` Linus Torvalds
2019-03-31 22:16                           ` Linus Torvalds
2019-03-31 22:33                           ` Christian Brauner [this message]
2019-03-31 22:33                             ` Christian Brauner
2019-04-01  0:52                             ` Jann Horn
2019-04-01  0:52                               ` Jann Horn
2019-04-01  8:47                               ` Yann Droneaud
2019-04-01  8:47                                 ` Yann Droneaud
2019-04-01 10:03                               ` Jonathan Kowalski
2019-04-01 10:03                                 ` Jonathan Kowalski
2019-03-31 23:40                           ` Linus Torvalds
2019-03-31 23:40                             ` Linus Torvalds
2019-04-01  0:09                             ` Al Viro
2019-04-01  0:09                               ` Al Viro
2019-04-01  0:18                               ` Linus Torvalds
2019-04-01  0:18                                 ` Linus Torvalds
2019-04-01  0:21                                 ` Christian Brauner
2019-04-01  0:21                                   ` Christian Brauner
2019-04-01  6:37                                 ` Al Viro
2019-04-01  6:37                                   ` Al Viro
2019-04-01  6:41                                   ` Al Viro
2019-04-01  6:41                                     ` Al Viro
2019-03-31 22:03                       ` Jonathan Kowalski
2019-03-31 22:03                         ` Jonathan Kowalski
2019-04-01  2:13                       ` Andy Lutomirski
2019-04-01  2:13                         ` Andy Lutomirski
2019-04-01 11:40                         ` Aleksa Sarai
2019-04-01 11:40                           ` Aleksa Sarai
2019-04-01 15:36                           ` Linus Torvalds
2019-04-01 15:36                             ` Linus Torvalds
2019-04-01 15:47                             ` Christian Brauner
2019-04-01 15:47                               ` Christian Brauner
2019-04-01 15:55                             ` Daniel Colascione
2019-04-01 15:55                               ` Daniel Colascione
2019-04-01 16:01                               ` Linus Torvalds
2019-04-01 16:01                                 ` Linus Torvalds
2019-04-01 16:13                                 ` Daniel Colascione
2019-04-01 16:13                                   ` Daniel Colascione
2019-04-01 19:42                                 ` Christian Brauner
2019-04-01 19:42                                   ` Christian Brauner
2019-04-01 21:30                                   ` Linus Torvalds
2019-04-01 21:30                                     ` Linus Torvalds
2019-04-01 21:58                                     ` Jonathan Kowalski
2019-04-01 21:58                                       ` Jonathan Kowalski
2019-04-01 22:13                                       ` Linus Torvalds
2019-04-01 22:13                                         ` Linus Torvalds
2019-04-01 22:34                                         ` Daniel Colascione
2019-04-01 22:34                                           ` Daniel Colascione
2019-04-01 16:07                               ` Jonathan Kowalski
2019-04-01 16:07                                 ` Jonathan Kowalski
2019-04-01 16:15                                 ` Linus Torvalds
2019-04-01 16:15                                   ` Linus Torvalds
2019-04-01 16:27                                   ` Jonathan Kowalski
2019-04-01 16:27                                     ` Jonathan Kowalski
2019-04-01 16:21                                 ` Daniel Colascione
2019-04-01 16:21                                   ` Daniel Colascione
2019-04-01 16:29                                   ` Linus Torvalds
2019-04-01 16:29                                     ` Linus Torvalds
2019-04-01 16:45                                     ` Daniel Colascione
2019-04-01 16:45                                       ` Daniel Colascione
2019-04-01 17:00                                       ` David Laight
2019-04-01 17:00                                         ` David Laight
2019-04-01 17:32                                       ` Linus Torvalds
2019-04-01 17:32                                         ` Linus Torvalds
2019-04-02 11:03                                       ` Florian Weimer
2019-04-02 11:03                                         ` Florian Weimer
2019-04-01 16:10                             ` Andy Lutomirski
2019-04-01 16:10                               ` Andy Lutomirski
2019-04-01 12:04                         ` Christian Brauner
2019-04-01 12:04                           ` Christian Brauner
2019-04-01 13:43                           ` Jann Horn
2019-04-01 13:43                             ` Jann Horn
2019-03-31 21:19                 ` Christian Brauner
2019-03-31 21:19                   ` Christian Brauner
2019-03-30 16:37       ` Christian Brauner
2019-03-30 16:37         ` Christian Brauner

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