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Re: scope of cred_guard_mutex.

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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

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Re: [RFC][PATCH] exec: Don't wait for ptraced threads to be reaped. ebiederm@xmission.com (Eric W. Biederman) - 2017-03-30 10:20 +0200
  [RFC][PATCH 0/2] exec: Fixing ptrace'd mulit-threaded hang ebiederm@xmission.com (Eric W. Biederman) - 2017-04-01 07:20 +0200
    [RFC][PATCH 1/2] sighand: Count each thread group once in sighand_struct ebiederm@xmission.com (Eric W. Biederman) - 2017-04-01 07:20 +0200
    [RFC][PATCH 2/2] exec: If possible don't wait for ptraced threads to be reaped ebiederm@xmission.com (Eric W. Biederman) - 2017-04-01 07:30 +0200
      Re: [RFC][PATCH 2/2] exec: If possible don't wait for ptraced  threads to be reaped Oleg Nesterov <oleg@redhat.com> - 2017-04-02 17:40 +0200
        Re: [RFC][PATCH 2/2] exec: If possible don't wait for ptraced threads to be reaped ebiederm@xmission.com (Eric W. Biederman) - 2017-04-02 21:00 +0200
          Re: [RFC][PATCH 2/2] exec: If possible don't wait for ptraced  threads to be reaped Oleg Nesterov <oleg@redhat.com> - 2017-04-03 20:20 +0200
            Re: [RFC][PATCH 2/2] exec: If possible don't wait for ptraced threads to be reaped ebiederm@xmission.com (Eric W. Biederman) - 2017-04-03 23:20 +0200
              Re: [RFC][PATCH 2/2] exec: If possible don't wait for ptraced         threads to be reaped Oleg Nesterov <oleg@redhat.com> - 2017-04-05 18:50 +0200
    Re: [RFC][PATCH 0/2] exec: Fixing ptrace'd mulit-threaded hang Oleg Nesterov <oleg@redhat.com> - 2017-04-02 17:40 +0200
    [RFC][PATCH v2 4/5] exec: If possible don't wait for ptraced threads to be reaped ebiederm@xmission.com (Eric W. Biederman) - 2017-04-03 01:00 +0200
      Re: [RFC][PATCH v2 4/5] exec: If possible don't wait for ptraced         threads to be reaped Oleg Nesterov <oleg@redhat.com> - 2017-04-05 18:20 +0200
    [RFC][PATCH v2 1/5] ptrace: Don't wait in PTRACE_O_TRACEEXIT for exec or coredump ebiederm@xmission.com (Eric W. Biederman) - 2017-04-03 01:00 +0200
      Re: [RFC][PATCH v2 1/5] ptrace: Don't wait in PTRACE_O_TRACEEXIT         for exec or coredump Oleg Nesterov <oleg@redhat.com> - 2017-04-05 18:30 +0200
    [RFC][PATCH v2 0/5] exec: Fixing ptrace'd mulit-threaded hang ebiederm@xmission.com (Eric W. Biederman) - 2017-04-03 01:00 +0200
      [RFC][PATCH v2 3/5] clone: Disallown CLONE_THREAD with a shared sighand_struct ebiederm@xmission.com (Eric W. Biederman) - 2017-04-03 01:00 +0200
        Re: [RFC][PATCH v2 3/5] clone: Disallown CLONE_THREAD with a         shared sighand_struct Oleg Nesterov <oleg@redhat.com> - 2017-04-05 18:30 +0200
          Re: [RFC][PATCH v2 3/5] clone: Disallown CLONE_THREAD with a shared sighand_struct ebiederm@xmission.com (Eric W. Biederman) - 2017-04-05 19:50 +0200
            Re: [RFC][PATCH v2 3/5] clone: Disallown CLONE_THREAD with a         shared sighand_struct Oleg Nesterov <oleg@redhat.com> - 2017-04-05 20:20 +0200
      [RFC][PATCH v2 2/5] sighand: Count each thread group once in sighand_struct ebiederm@xmission.com (Eric W. Biederman) - 2017-04-03 01:00 +0200
      [RFC][PATCH v2 5/5] signal: Don't allow accessing signal_struct by old threads after exec ebiederm@xmission.com (Eric W. Biederman) - 2017-04-03 01:10 +0200
        Re: [RFC][PATCH v2 5/5] signal: Don't allow accessing         signal_struct by old threads after exec Oleg Nesterov <oleg@redhat.com> - 2017-04-05 18:20 +0200
          Re: [RFC][PATCH v2 5/5] signal: Don't allow accessing signal_struct by old threads after exec ebiederm@xmission.com (Eric W. Biederman) - 2017-04-05 20:30 +0200
            Re: [RFC][PATCH v2 5/5] signal: Don't allow accessing signal_struct  by old threads after exec Oleg Nesterov <oleg@redhat.com> - 2017-04-06 18:00 +0200
  Re: [RFC][PATCH] exec: Don't wait for ptraced threads to be reaped. Oleg Nesterov <oleg@redhat.com> - 2017-04-02 18:20 +0200
    Re: [RFC][PATCH] exec: Don't wait for ptraced threads to be reaped. ebiederm@xmission.com (Eric W. Biederman) - 2017-04-02 23:20 +0200
      Re: [RFC][PATCH] exec: Don't wait for ptraced threads to be reaped. Oleg Nesterov <oleg@redhat.com> - 2017-04-03 20:40 +0200
        scope of cred_guard_mutex. ebiederm@xmission.com (Eric W. Biederman) - 2017-04-04 01:00 +0200
          Re: scope of cred_guard_mutex. Oleg Nesterov <oleg@redhat.com> - 2017-04-05 18:10 +0200
            Re: scope of cred_guard_mutex. Kees Cook <keescook@chromium.org> - 2017-04-05 18:20 +0200
            Re: scope of cred_guard_mutex. ebiederm@xmission.com (Eric W. Biederman) - 2017-04-05 20:10 +0200
              Re: scope of cred_guard_mutex. Oleg Nesterov <oleg@redhat.com> - 2017-04-05 20:20 +0200
          Re: scope of cred_guard_mutex. Oleg Nesterov <oleg@redhat.com> - 2017-04-06 18:00 +0200
            Re: scope of cred_guard_mutex. Kees Cook <keescook@chromium.org> - 2017-04-08 00:10 +0200
        Re: [RFC][PATCH] exec: Don't wait for ptraced threads to be reaped. ebiederm@xmission.com (Eric W. Biederman) - 2017-04-04 01:00 +0200

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