From: Peter Zijlstra <peterz@infradead.org>
To: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>,
Linus Torvalds <torvalds@linux-foundation.org>,
Bernd Edlinger <bernd.edlinger@hotmail.de>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Ingo Molnar <mingo@redhat.com>, Will Deacon <will@kernel.org>,
Jann Horn <jannh@google.com>,
Vasiliy Kulikov <segoon@openwall.com>,
Al Viro <viro@zeniv.linux.org.uk>,
Oleg Nesterov <oleg@redhat.com>,
Cyrill Gorcunov <gorcunov@gmail.com>,
Sargun Dhillon <sargun@sargun.me>,
Christian Brauner <christian.brauner@ubuntu.com>,
Arnd Bergmann <arnd@arndb.de>,
Arnaldo Carvalho de Melo <acme@kernel.org>,
Waiman Long <longman@redhat.com>
Subject: Re: [PATCH 3/3] exec: Transform exec_update_mutex into a rw_semaphore
Date: Mon, 7 Dec 2020 10:15:02 +0100 [thread overview]
Message-ID: <20201207091502.GG3040@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <878sacyvpv.fsf@x220.int.ebiederm.org>
On Sat, Dec 05, 2020 at 12:05:32PM -0600, Eric W. Biederman wrote:
> I am trying to understand why the permission check is there.
It's about observability, is task A allowed to observe state of task B?
By installing a perf event on another task, we can very accurately tell
what it's doing, and isn't fundamentally different from attaching a
debugger (ie. ptrace).
Therefore we chose to use the same security checks. As is good custom,
one does security checks early.
Then Jann came and observed that race against execve mucking with privs,
and we got to hold that mutex across lots.
That patch I proposed earlier should solve that all.
next prev parent reply other threads:[~2020-12-07 9:16 UTC|newest]
Thread overview: 46+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-03 20:09 [PATCH 0/3] exec: Transform exec_update_mutex into a rw_semaphore Eric W. Biederman
2020-12-03 20:10 ` [PATCH 1/3] rwsem: Implement down_read_killable_nested Eric W. Biederman
2020-12-04 1:58 ` Waiman Long
2020-12-09 18:38 ` [tip: locking/core] " tip-bot2 for Eric W. Biederman
2020-12-03 20:11 ` [PATCH 2/3] rwsem: Implement down_read_interruptible Eric W. Biederman
2020-12-04 1:59 ` Waiman Long
2020-12-07 9:02 ` Peter Zijlstra
2020-12-07 15:33 ` Waiman Long
2020-12-07 16:58 ` David Laight
2020-12-07 19:02 ` Waiman Long
2020-12-08 9:12 ` David Laight
2020-12-08 12:32 ` Peter Zijlstra
2020-12-08 13:13 ` David Laight
2020-12-08 15:34 ` Waiman Long
2020-12-08 16:23 ` David Laight
2020-12-07 15:56 ` Eric W. Biederman
2020-12-08 14:52 ` Peter Zijlstra
2020-12-08 18:27 ` Eric W. Biederman
2020-12-09 18:36 ` Peter Zijlstra
2020-12-10 19:33 ` Eric W. Biederman
2020-12-11 8:16 ` Peter Zijlstra
2020-12-09 18:38 ` [tip: locking/core] locking/rwsem: Introduce rwsem_write_trylock() tip-bot2 for Peter Zijlstra
2020-12-09 18:38 ` [tip: locking/core] locking/rwsem: Fold __down_{read,write}*() tip-bot2 for Peter Zijlstra
2020-12-09 18:38 ` [tip: locking/core] locking/rwsem: Better collate rwsem_read_trylock() tip-bot2 for Peter Zijlstra
2020-12-09 18:38 ` [tip: locking/core] rwsem: Implement down_read_interruptible tip-bot2 for Eric W. Biederman
2020-12-03 20:12 ` [PATCH 3/3] exec: Transform exec_update_mutex into a rw_semaphore Eric W. Biederman
2020-12-04 16:08 ` Bernd Edlinger
2020-12-04 17:21 ` Linus Torvalds
2020-12-04 19:34 ` Eric W. Biederman
2020-12-04 20:10 ` Linus Torvalds
2020-12-04 20:30 ` Bernd Edlinger
2020-12-04 20:48 ` Linus Torvalds
2020-12-04 21:48 ` Davidlohr Bueso
2020-12-05 18:05 ` Eric W. Biederman
2020-12-07 9:15 ` Peter Zijlstra [this message]
2020-12-07 9:09 ` Peter Zijlstra
2020-12-07 18:40 ` Linus Torvalds
2020-12-08 8:34 ` [PATCH] perf: Break deadlock involving exec_update_mutex Peter Zijlstra
2020-12-08 18:37 ` Linus Torvalds
2020-12-10 18:38 ` Davidlohr Bueso
2020-12-10 19:40 ` Eric W. Biederman
2020-12-05 17:43 ` [PATCH 3/3] exec: Transform exec_update_mutex into a rw_semaphore Eric W. Biederman
2020-12-04 17:39 ` Eric W. Biederman
2020-12-03 22:42 ` [PATCH 0/3] " Linus Torvalds
2020-12-04 1:56 ` Waiman Long
2020-12-04 4:54 ` Davidlohr Bueso
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