linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
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>,
	Eugene Syromiatnikov <esyr@redhat.com>
Subject: Re: scope of cred_guard_mutex.
Date: Fri, 7 Apr 2017 15:07:24 -0700	[thread overview]
Message-ID: <CAGXu5jLDQTZm8meX3bkPgjg3GdfXEOA6Z8Boy0HZeM04G7yasQ@mail.gmail.com> (raw)
In-Reply-To: <20170406155540.GC7444@redhat.com>

On Thu, Apr 6, 2017 at 8:55 AM, Oleg Nesterov <oleg@redhat.com> wrote:
> And this makes me think again that we need to restart this discusion with
> more CC's.

I'm a fan of that; I've not been able to follow this thread as it
seems to have gone far from the original deadlock problem. :) I've
seen issues with ptrace, zombies, and now exec. I'm lost. :P

>> Partly I object because your understanding and my understanding of
>> cred_guard_mutex are very different.
>>
>> As I read and understand the code the job of cred_guard_mutex is to keep
>> ptrace (and other threads of the proccess) from interferring in
>> exec and to ensure old resources are accessed with permission checks
>> using our original credentials and that new and modified resources are
>> accessed with permission checks using our new credentials.
>
> Yes, this is clear.

Maybe stupid idea: can we get a patch that just adds this kind of
documentation somewhere in the source? If we can agree on the purpose
of cred_guard_mutex, and get it into the code, that seems like a good
step in discussion...

-Kees

-- 
Kees Cook
Pixel Security

  reply	other threads:[~2017-04-07 22:07 UTC|newest]

Thread overview: 63+ 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 18:59         ` 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
2017-03-04 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  5:14                     ` [RFC][PATCH 1/2] sighand: Count each thread group once in sighand_struct 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
2017-04-02 15:35                       ` Oleg Nesterov
2017-04-02 18:53                         ` Eric W. Biederman
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 22:50                     ` [RFC][PATCH v2 0/5] " 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
2017-04-05 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 22:52                       ` [RFC][PATCH v2 3/5] clone: Disallown CLONE_THREAD with a shared sighand_struct Eric W. Biederman
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
2017-04-05 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
2017-04-05 16:18                         ` Oleg Nesterov
2017-04-05 18:16                           ` Eric W. Biederman
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 21:07                     ` Eric W. Biederman
2017-04-03 18:37                       ` Oleg Nesterov
2017-04-03 22:49                         ` Eric W. Biederman
2017-04-03 22:49                         ` scope of cred_guard_mutex Eric W. Biederman
2017-04-05 16:08                           ` Oleg Nesterov
2017-04-05 16:11                             ` Kees Cook
2017-04-05 17:53                             ` Eric W. Biederman
2017-04-05 18:15                               ` Oleg Nesterov
2017-04-06 15:55                           ` Oleg Nesterov
2017-04-07 22:07                             ` Kees Cook [this message]
2017-09-04  3:19                       ` [RFC][PATCH] exec: Don't wait for ptraced threads to be reaped Robert O'Callahan
2017-03-04 16:54         ` [PATCH 0/2] fix the traced mt-exec deadlock Oleg Nesterov

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=CAGXu5jLDQTZm8meX3bkPgjg3GdfXEOA6Z8Boy0HZeM04G7yasQ@mail.gmail.com \
    --to=keescook@chromium.org \
    --cc=afazekas@redhat.com \
    --cc=akpm@linux-foundation.org \
    --cc=asarai@suse.com \
    --cc=ebiederm@xmission.com \
    --cc=esyr@redhat.com \
    --cc=jann@thejh.net \
    --cc=linux-api@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=luto@amacapital.net \
    --cc=mhocko@kernel.org \
    --cc=oleg@redhat.com \
    --cc=uobergfe@redhat.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).