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From: Kees Cook <keescook@chromium.org>
To: Oleg Nesterov <oleg@redhat.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Aleksa Sarai <asarai@suse.com>,
	Andy Lutomirski <luto@amacapital.net>,
	Attila Fazekas <afazekas@redhat.com>, Jann Horn <jann@thejh.net>,
	Michal Hocko <mhocko@kernel.org>,
	Ulrich Obergfell <uobergfe@redhat.com>,
	LKML <linux-kernel@vger.kernel.org>,
	Linux API <linux-api@vger.kernel.org>
Subject: Re: scope of cred_guard_mutex.
Date: Wed, 5 Apr 2017 09:11:18 -0700	[thread overview]
Message-ID: <CAGXu5j+ngHnxcauv1aJYZke0TQ8LxMxt9nv-=q+EjG33dPzyrA@mail.gmail.com> (raw)
In-Reply-To: <20170405160845.GA14536@redhat.com>

On Wed, Apr 5, 2017 at 9:08 AM, Oleg Nesterov <oleg@redhat.com> wrote:
> On 04/03, Eric W. Biederman wrote:
>>
>> You have asked why I have problems with your patch and so I am going to
>> try to explain.  Partly I want to see a clean set of patches that we
>> can merge into Linus's tree before we make any compromises.  Because the
>> work preparing a clean patchset may inform us of something better.  Plus
>> we need to make something clean and long term maintainable in any event.
>>
>> Partly I object because your understanding and my understanding of
>> cred_guard_mutex are very different.
>
> And I think there is another problem, your understanding and my understanding
> of "clean" differ too much and it seems that we can not convince each other ;)
>
> The last series looks buggy (I'll send more emails later today), but the
> main problem is that - in my opinion! - your approach is "obviously wrong
> and much less clean". But yes, yes, I understand that this is my opinion,
> and I can be wrong.
>
> Eric, I think we need more CC's. Linus, probably security list, the more
> the better.
>
> I am going to resend my series with more CC's, then you can nack it and
> explain what you think we should do. Perhaps someone else will suggest
> a better solution, or at least review the patches. OK?

I've been following along, but it seems like there are a lot of edge
cases in these changes. I'll try to meaningfully comment on the coming
emails... having code examples of why various things will/won't work
go a long way for helping understand what's safe or not...

-Kees

-- 
Kees Cook
Pixel Security

  reply	other threads:[~2017-04-05 16:11 UTC|newest]

Thread overview: 93+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-02-13 14:14 [PATCH 0/2] fix the traced mt-exec deadlock Oleg Nesterov
2017-02-13 14:15 ` [PATCH 1/2] exec: don't wait for zombie threads with cred_guard_mutex held Oleg Nesterov
2017-02-13 16:12   ` kbuild test robot
2017-02-13 16:47     ` Oleg Nesterov
2017-02-13 16:39   ` kbuild test robot
2017-02-13 17:27   ` Mika Penttilä
2017-02-13 18:01     ` Oleg Nesterov
2017-02-13 18:04   ` [PATCH V2 " Oleg Nesterov
2017-02-16 11:42     ` Eric W. Biederman
2017-02-20 15:22       ` Oleg Nesterov
2017-02-20 15:36         ` Oleg Nesterov
2017-02-20 22:30         ` Eric W. Biederman
2017-02-21 17:53           ` Oleg Nesterov
2017-02-21 20:20             ` Eric W. Biederman
2017-02-22 17:41               ` Oleg Nesterov
2017-02-17  4:42     ` Eric W. Biederman
2017-02-20 15:50       ` Oleg Nesterov
2017-02-13 14:15 ` [PATCH 2/2] ptrace: ensure PTRACE_EVENT_EXIT won't stop if the tracee is killed by exec Oleg Nesterov
2017-02-24 16:03 ` [PATCH 0/2] fix the traced mt-exec deadlock Oleg Nesterov
2017-03-03  1:05   ` Eric W. Biederman
2017-03-03 17:33     ` Oleg Nesterov
2017-03-03 18:23       ` Eric W. Biederman
2017-03-03 18:23         ` Eric W. Biederman
2017-03-03 18:59         ` Eric W. Biederman
2017-03-03 18:59           ` Eric W. Biederman
2017-03-03 20:06           ` Eric W. Biederman
2017-03-03 20:06             ` Eric W. Biederman
2017-03-03 20:11             ` [RFC][PATCH] exec: Don't wait for ptraced threads to be reaped Eric W. Biederman
2017-03-03 20:11               ` Eric W. Biederman
2017-03-04 17:03               ` Oleg Nesterov
2017-03-30  8:07                 ` Eric W. Biederman
2017-04-01  5:11                   ` [RFC][PATCH 0/2] exec: Fixing ptrace'd mulit-threaded hang Eric W. Biederman
2017-04-01  5:11                     ` Eric W. Biederman
2017-04-01  5:14                     ` [RFC][PATCH 1/2] sighand: Count each thread group once in sighand_struct Eric W. Biederman
2017-04-01  5:14                       ` Eric W. Biederman
2017-04-01  5:16                     ` [RFC][PATCH 2/2] exec: If possible don't wait for ptraced threads to be reaped Eric W. Biederman
2017-04-01  5:16                       ` Eric W. Biederman
2017-04-02 15:35                       ` Oleg Nesterov
2017-04-02 15:35                         ` Oleg Nesterov
2017-04-02 18:53                         ` Eric W. Biederman
2017-04-02 18:53                           ` Eric W. Biederman
2017-04-03 18:12                           ` Oleg Nesterov
2017-04-03 18:12                             ` Oleg Nesterov
2017-04-03 21:04                             ` Eric W. Biederman
2017-04-05 16:44                               ` Oleg Nesterov
2017-04-02 15:38                     ` [RFC][PATCH 0/2] exec: Fixing ptrace'd mulit-threaded hang Oleg Nesterov
2017-04-02 15:38                       ` Oleg Nesterov
2017-04-02 22:50                     ` [RFC][PATCH v2 0/5] " Eric W. Biederman
2017-04-02 22:50                       ` Eric W. Biederman
2017-04-02 22:51                       ` [RFC][PATCH v2 1/5] ptrace: Don't wait in PTRACE_O_TRACEEXIT for exec or coredump Eric W. Biederman
2017-04-02 22:51                         ` Eric W. Biederman
2017-04-05 16:19                         ` Oleg Nesterov
2017-04-02 22:51                       ` [RFC][PATCH v2 2/5] sighand: Count each thread group once in sighand_struct Eric W. Biederman
2017-04-02 22:51                         ` Eric W. Biederman
2017-04-02 22:52                       ` [RFC][PATCH v2 3/5] clone: Disallown CLONE_THREAD with a shared sighand_struct Eric W. Biederman
2017-04-02 22:52                         ` Eric W. Biederman
2017-04-05 16:24                         ` Oleg Nesterov
2017-04-05 16:24                           ` Oleg Nesterov
2017-04-05 17:34                           ` Eric W. Biederman
2017-04-05 18:11                             ` Oleg Nesterov
2017-04-02 22:53                       ` [RFC][PATCH v2 4/5] exec: If possible don't wait for ptraced threads to be reaped Eric W. Biederman
2017-04-02 22:53                         ` Eric W. Biederman
2017-04-05 16:15                         ` Oleg Nesterov
2017-04-02 22:57                       ` [RFC][PATCH v2 5/5] signal: Don't allow accessing signal_struct by old threads after exec Eric W. Biederman
2017-04-02 22:57                         ` Eric W. Biederman
2017-04-05 16:18                         ` Oleg Nesterov
2017-04-05 16:18                           ` Oleg Nesterov
2017-04-05 18:16                           ` Eric W. Biederman
2017-04-05 18:16                             ` Eric W. Biederman
2017-04-06 15:48                             ` Oleg Nesterov
2017-04-06 15:48                               ` Oleg Nesterov
2017-04-02 16:15                   ` [RFC][PATCH] exec: Don't wait for ptraced threads to be reaped Oleg Nesterov
2017-04-02 16:15                     ` Oleg Nesterov
2017-04-02 21:07                     ` Eric W. Biederman
2017-04-02 21:07                       ` Eric W. Biederman
2017-04-03 18:37                       ` Oleg Nesterov
2017-04-03 18:37                         ` Oleg Nesterov
2017-04-03 22:49                         ` Eric W. Biederman
2017-04-03 22:49                           ` Eric W. Biederman
2017-04-03 22:49                         ` scope of cred_guard_mutex Eric W. Biederman
2017-04-03 22:49                           ` Eric W. Biederman
2017-04-05 16:08                           ` Oleg Nesterov
2017-04-05 16:11                             ` Kees Cook [this message]
2017-04-05 17:53                             ` Eric W. Biederman
2017-04-05 18:15                               ` Oleg Nesterov
2017-04-06 15:55                           ` Oleg Nesterov
2017-04-06 15:55                             ` Oleg Nesterov
2017-04-07 22:07                             ` Kees Cook
2017-04-07 22:07                               ` Kees Cook
2017-09-04  3:19                       ` [RFC][PATCH] exec: Don't wait for ptraced threads to be reaped Robert O'Callahan
2017-09-04  3:19                         ` Robert O'Callahan
2017-03-04 16:54         ` [PATCH 0/2] fix the traced mt-exec deadlock Oleg Nesterov
2017-03-04 16:54           ` Oleg Nesterov

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