From: Linus Torvalds <torvalds@linux-foundation.org>
To: Jann Horn <jannh@google.com>
Cc: Joel Fernandes <joel@joelfernandes.org>,
Daniel Colascione <dancol@google.com>,
Christian Brauner <christian@brauner.io>,
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>
Subject: Re: [PATCH v2 0/5] pid: add pidfd_open()
Date: Sun, 31 Mar 2019 07:52:28 -0700 [thread overview]
Message-ID: <CAHk-=wiZ40LVjnXSi9iHLE_-ZBsWFGCgdmNiYZUXn1-V5YBg2g@mail.gmail.com> (raw)
In-Reply-To: <CAG48ez2gb94SqS30Ai4+VBHhnzBp5Po9_u00nMrvUW6Wqq6hPA@mail.gmail.com>
On Sat, Mar 30, 2019 at 9:47 PM Jann Horn <jannh@google.com> wrote:
>
> Sure, given a pidfd_clone() syscall, as long as the parent of the
> process is giving you a pidfd for it and you don't have to deal with
> grandchildren created by fork() calls outside your control, that
> works.
Don't do pidfd_clone() and pidfd_wait().
Both of those existing system calls already get a "flags" argument.
Just make a WPIDFD (for waitid) and CLONE_PIDFD (for clone) bit, and
make the existing system calls just take/return a pidfd.
Side note: we could (should?) also make the default maxpid just be
larger. It needs to fit in an 'int', but MAXINT instead of 65535 would
likely alreadt make a lot of these attacks harder.
There was some really old legacy reason why we actually limited it to
65535 originally. It was old and crufty even back when..
Linus
Linus
WARNING: multiple messages have this Message-ID (diff)
From: Linus Torvalds <torvalds@linux-foundation.org>
To: Jann Horn <jannh@google.com>
Cc: Joel Fernandes <joel@joelfernandes.org>,
Daniel Colascione <dancol@google.com>,
Christian Brauner <christian@brauner.io>,
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
Subject: Re: [PATCH v2 0/5] pid: add pidfd_open()
Date: Sun, 31 Mar 2019 07:52:28 -0700 [thread overview]
Message-ID: <CAHk-=wiZ40LVjnXSi9iHLE_-ZBsWFGCgdmNiYZUXn1-V5YBg2g@mail.gmail.com> (raw)
In-Reply-To: <CAG48ez2gb94SqS30Ai4+VBHhnzBp5Po9_u00nMrvUW6Wqq6hPA@mail.gmail.com>
On Sat, Mar 30, 2019 at 9:47 PM Jann Horn <jannh@google.com> wrote:
>
> Sure, given a pidfd_clone() syscall, as long as the parent of the
> process is giving you a pidfd for it and you don't have to deal with
> grandchildren created by fork() calls outside your control, that
> works.
Don't do pidfd_clone() and pidfd_wait().
Both of those existing system calls already get a "flags" argument.
Just make a WPIDFD (for waitid) and CLONE_PIDFD (for clone) bit, and
make the existing system calls just take/return a pidfd.
Side note: we could (should?) also make the default maxpid just be
larger. It needs to fit in an 'int', but MAXINT instead of 65535 would
likely alreadt make a lot of these attacks harder.
There was some really old legacy reason why we actually limited it to
65535 originally. It was old and crufty even back when..
Linus
Linus
next prev parent reply other threads:[~2019-03-31 14:52 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 [this message]
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
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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