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
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From: Kees Cook <keescook-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org> To: Oleg Nesterov <oleg-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org> Cc: "Eric W. Biederman" <ebiederm-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org>, Andrew Morton <akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org>, Aleksa Sarai <asarai-IBi9RG/b67k@public.gmane.org>, Andy Lutomirski <luto-kltTT9wpgjJwATOyAt5JVQ@public.gmane.org>, Attila Fazekas <afazekas-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>, Jann Horn <jann-XZ1E9jl8jIdeoWH0uzbU5w@public.gmane.org>, Michal Hocko <mhocko-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>, Ulrich Obergfell <uobergfe-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>, LKML <linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>, Linux API <linux-api-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>, Eugene Syromiatnikov <esyr-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org> 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-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org> On Thu, Apr 6, 2017 at 8:55 AM, Oleg Nesterov <oleg-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org> 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
next prev parent reply other threads:[~2017-04-07 22:07 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 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 [this message] 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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