From: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
To: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Alexei Starovoitov <alexei.starovoitov@gmail.com>,
linux-kernel@vger.kernel.org, David Miller <davem@davemloft.net>,
Greg Kroah-Hartman <greg@kroah.com>,
Kees Cook <keescook@chromium.org>,
Andrew Morton <akpm@linux-foundation.org>,
Alexei Starovoitov <ast@kernel.org>,
Al Viro <viro@zeniv.linux.org.uk>, bpf <bpf@vger.kernel.org>,
linux-fsdevel <linux-fsdevel@vger.kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Jakub Kicinski <kuba@kernel.org>,
Masahiro Yamada <yamada.masahiro@socionext.com>,
Gary Lin <GLin@suse.com>, Bruno Meneguele <bmeneg@redhat.com>,
LSM List <linux-security-module@vger.kernel.org>,
Casey Schaufler <casey@schaufler-ca.com>,
Luis Chamberlain <mcgrof@kernel.org>,
Linus Torvalds <torvalds@linux-foundation.org>
Subject: Re: [PATCH v2 00/15] Make the user mode driver code a better citizen
Date: Thu, 2 Jul 2020 22:40:09 +0900
Message-ID: <757f37f8-5641-91d2-be80-a96ebc74cacb@i-love.sakura.ne.jp> (raw)
In-Reply-To: <87pn9euks9.fsf@x220.int.ebiederm.org>
On 2020/07/02 22:08, Eric W. Biederman wrote:
> Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp> writes:
>
>> On 2020/06/30 21:29, Eric W. Biederman wrote:
>>> Hmm. The wake up happens just of tgid->wait_pidfd happens just before
>>> release_task is called so there is a race. As it is possible to wake
>>> up and then go back to sleep before pid_has_task becomes false.
>>
>> What is the reason we want to wait until pid_has_task() becomes false?
>>
>> - wait_event(tgid->wait_pidfd, !pid_has_task(tgid, PIDTYPE_TGID));
>> + while (!wait_event_timeout(tgid->wait_pidfd, !pid_has_task(tgid, PIDTYPE_TGID), 1));
>
> So that it is safe to call bpfilter_umh_cleanup. The previous code
> performed the wait by having a callback in do_exit.
But bpfilter_umh_cleanup() does only
fput(info->pipe_to_umh);
fput(info->pipe_from_umh);
put_pid(info->tgid);
info->tgid = NULL;
which is (I think) already safe regardless of the usermode process because
bpfilter_umh_cleanup() merely closes one side of two pipes used between
two processes and forgets about the usermode process.
>
> It might be possible to call bpf_umh_cleanup early but I have not done
> that analysis.
>
> To perform the test correctly what I have right now is:
Waiting for the termination of a SIGKILLed usermode process is not
such simple. If a usermode process was killed by the OOM killer, it
might take minutes for the killed process to reach do_exit() due to
invisible memory allocation dependency chain. Since the OOM killer
kicks the OOM reaper, and the OOM reaper forgets about the killed
process after one second if mmap_sem could not be held (in order to
avoid OOM deadlock), the OOM situation will be eventually solved; but
there is no guarantee that the killed process can reach do_exit()
in a short period.
next prev parent reply index
Thread overview: 193+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20200329005528.xeKtdz2A0%akpm@linux-foundation.org>
[not found] ` <13fb3ab7-9ab1-b25f-52f2-40a6ca5655e1@i-love.sakura.ne.jp>
[not found] ` <202006051903.C44988B@keescook>
2020-06-06 19:20 ` [RFC][PATCH] net/bpfilter: Remove this broken and apparently unmantained Eric W. Biederman
2020-06-06 20:19 ` Alexei Starovoitov
2020-06-06 22:33 ` Linus Torvalds
2020-06-07 1:49 ` Alexei Starovoitov
2020-06-07 2:19 ` Linus Torvalds
2020-06-07 16:09 ` Eric W. Biederman
2020-06-08 16:20 ` Alexei Starovoitov
2020-06-08 16:40 ` Greg KH
2020-06-08 18:35 ` Kees Cook
2020-06-09 1:26 ` Alexei Starovoitov
2020-06-09 15:37 ` Kees Cook
2020-06-09 19:51 ` Eric W. Biederman
2020-06-07 2:31 ` Tetsuo Handa
2020-06-08 16:23 ` Alexei Starovoitov
2020-06-08 23:22 ` Tetsuo Handa
2020-06-09 1:28 ` Alexei Starovoitov
2020-06-09 5:29 ` Tetsuo Handa
2020-06-09 22:32 ` Alexei Starovoitov
2020-06-09 23:30 ` Tetsuo Handa
2020-06-10 0:05 ` Alexei Starovoitov
2020-06-10 3:08 ` Tetsuo Handa
2020-06-10 3:32 ` Alexei Starovoitov
2020-06-10 7:30 ` Tetsuo Handa
2020-06-10 16:24 ` Casey Schaufler
2020-06-09 20:02 ` Eric W. Biederman
2020-06-09 23:56 ` Alexei Starovoitov
2020-06-10 21:12 ` Eric W. Biederman
2020-06-11 23:31 ` Alexei Starovoitov
2020-06-12 0:57 ` Tetsuo Handa
2020-06-13 3:38 ` Alexei Starovoitov
2020-06-13 4:22 ` Tetsuo Handa
2020-06-13 14:08 ` Eric W. Biederman
2020-06-13 15:33 ` Alexei Starovoitov
2020-06-13 16:14 ` Alexei Starovoitov
2020-06-14 14:51 ` Eric W. Biederman
2020-06-16 1:55 ` Alexei Starovoitov
2020-06-16 16:21 ` Alexei Starovoitov
2020-06-23 18:04 ` Eric W. Biederman
2020-06-23 18:35 ` Alexei Starovoitov
2020-06-23 18:53 ` Eric W. Biederman
2020-06-23 19:40 ` Alexei Starovoitov
2020-06-24 1:51 ` Tetsuo Handa
2020-06-24 4:00 ` Alexei Starovoitov
2020-06-24 4:58 ` Tetsuo Handa
2020-06-24 6:39 ` Alexei Starovoitov
2020-06-24 7:05 ` Tetsuo Handa
2020-06-24 15:41 ` Casey Schaufler
2020-06-24 17:54 ` Alexei Starovoitov
2020-06-24 19:48 ` Casey Schaufler
2020-06-24 6:05 ` Alexei Starovoitov
2020-06-24 14:18 ` Alexei Starovoitov
2020-06-24 12:13 ` Eric W. Biederman
2020-06-24 14:26 ` Alexei Starovoitov
2020-06-24 23:14 ` Tetsuo Handa
2020-06-25 1:35 ` Alexei Starovoitov
2020-06-25 6:38 ` Tetsuo Handa
2020-06-25 9:57 ` Greg KH
2020-06-25 11:03 ` Tetsuo Handa
2020-06-25 12:07 ` Greg KH
2020-06-25 14:21 ` Tetsuo Handa
2020-06-25 19:34 ` David Miller
2020-06-26 1:36 ` Linus Torvalds
2020-06-26 1:51 ` Alexei Starovoitov
2020-06-26 4:58 ` Tetsuo Handa
2020-06-26 5:41 ` Alexei Starovoitov
2020-06-26 6:20 ` Tetsuo Handa
2020-06-26 6:39 ` Alexei Starovoitov
2020-06-26 12:51 ` [PATCH 00/14] Make the user mode driver code a better citizen Eric W. Biederman
2020-06-26 12:53 ` [PATCH 01/14] umh: Capture the pid in umh_pipe_setup Eric W. Biederman
2020-06-26 12:53 ` [PATCH 02/14] umh: Move setting PF_UMH into umh_pipe_setup Eric W. Biederman
2020-06-26 12:54 ` [PATCH 03/14] umh: Rename the user mode driver helpers for clarity Eric W. Biederman
2020-06-26 12:54 ` [PATCH 04/14] umh: Remove call_usermodehelper_setup_file Eric W. Biederman
2020-06-26 12:55 ` [PATCH 05/14] umh: Separate the user mode driver and the user mode helper support Eric W. Biederman
2020-06-26 16:22 ` Tetsuo Handa
2020-06-26 16:45 ` Eric W. Biederman
2020-06-27 1:26 ` Tetsuo Handa
2020-06-27 4:21 ` Eric W. Biederman
2020-06-27 4:36 ` Tetsuo Handa
2020-06-26 12:55 ` [PATCH 06/14] umd: For clarity rename umh_info umd_info Eric W. Biederman
2020-06-26 15:37 ` Kees Cook
2020-06-26 16:31 ` Eric W. Biederman
2020-06-26 12:56 ` [PATCH 07/14] umd: Rename umd_info.cmdline umd_info.driver_name Eric W. Biederman
2020-06-26 12:56 ` [PATCH 08/14] umd: Transform fork_usermode_blob into fork_usermode_driver Eric W. Biederman
2020-06-26 12:57 ` [PATCH 09/14] umh: Stop calling do_execve_file Eric W. Biederman
2020-06-26 12:57 ` [PATCH 10/14] exec: Remove do_execve_file Eric W. Biederman
2020-06-26 12:58 ` [PATCH 11/14] bpfilter: Move bpfilter_umh back into init data Eric W. Biederman
2020-06-26 12:58 ` [PATCH 12/14] umd: Track user space drivers with struct pid Eric W. Biederman
2020-06-26 12:59 ` [PATCH 13/14] bpfilter: Take advantage of the facilities of " Eric W. Biederman
2020-06-26 12:59 ` [PATCH 14/14] umd: Remove exit_umh Eric W. Biederman
2020-06-26 13:48 ` [PATCH 00/14] Make the user mode driver code a better citizen Eric W. Biederman
2020-06-29 19:55 ` [PATCH v2 00/15] " Eric W. Biederman
2020-06-29 19:56 ` [PATCH v2 01/15] umh: Capture the pid in umh_pipe_setup Eric W. Biederman
2020-06-29 19:57 ` [PATCH v2 02/15] umh: Move setting PF_UMH into umh_pipe_setup Eric W. Biederman
2020-06-29 19:57 ` [PATCH v2 03/15] umh: Rename the user mode driver helpers for clarity Eric W. Biederman
2020-06-29 19:59 ` [PATCH v2 04/15] umh: Remove call_usermodehelper_setup_file Eric W. Biederman
2020-06-29 20:00 ` [PATCH v2 05/15] umh: Separate the user mode driver and the user mode helper support Eric W. Biederman
2020-06-30 16:58 ` Linus Torvalds
2020-07-01 17:18 ` Eric W. Biederman
2020-07-01 17:42 ` Alexei Starovoitov
2020-06-29 20:01 ` [PATCH v2 06/15] umd: For clarity rename umh_info umd_info Eric W. Biederman
2020-06-29 20:02 ` [PATCH v2 07/15] umd: Rename umd_info.cmdline umd_info.driver_name Eric W. Biederman
2020-06-29 20:03 ` [PATCH v2 08/15] umd: Transform fork_usermode_blob into fork_usermode_driver Eric W. Biederman
2020-06-29 20:03 ` [PATCH v2 09/15] umh: Stop calling do_execve_file Eric W. Biederman
2020-06-29 20:04 ` [PATCH v2 10/15] exec: Remove do_execve_file Eric W. Biederman
2020-06-30 5:43 ` Christoph Hellwig
2020-06-30 12:14 ` Eric W. Biederman
2020-06-30 13:38 ` Christoph Hellwig
2020-06-30 14:28 ` Eric W. Biederman
2020-06-30 16:55 ` Alexei Starovoitov
2020-06-29 20:05 ` [PATCH v2 11/15] bpfilter: Move bpfilter_umh back into init data Eric W. Biederman
2020-06-29 20:06 ` [PATCH v2 12/15] umd: Track user space drivers with struct pid Eric W. Biederman
2020-06-29 20:06 ` [PATCH v2 13/15] bpfilter: Take advantage of the facilities of " Eric W. Biederman
2020-06-29 20:07 ` [PATCH v2 14/15] umd: Remove exit_umh Eric W. Biederman
2020-06-29 20:08 ` [PATCH v2 15/15] umd: Stop using split_argv Eric W. Biederman
2020-06-29 22:12 ` [PATCH v2 00/15] Make the user mode driver code a better citizen Alexei Starovoitov
2020-06-30 1:13 ` Eric W. Biederman
2020-06-30 6:16 ` Tetsuo Handa
2020-06-30 12:29 ` Eric W. Biederman
2020-06-30 13:21 ` Tetsuo Handa
2020-07-02 13:08 ` Eric W. Biederman
2020-07-02 13:40 ` Tetsuo Handa [this message]
2020-07-02 16:02 ` Eric W. Biederman
2020-07-03 13:19 ` Tetsuo Handa
2020-07-03 22:25 ` Eric W. Biederman
2020-07-04 6:57 ` Tetsuo Handa
2020-07-08 4:46 ` Eric W. Biederman
2020-06-30 16:52 ` Alexei Starovoitov
2020-07-01 17:12 ` Eric W. Biederman
2020-07-02 16:40 ` [PATCH v3 00/16] " Eric W. Biederman
2020-07-02 16:41 ` [PATCH v3 01/16] umh: Capture the pid in umh_pipe_setup Eric W. Biederman
2020-07-02 16:41 ` [PATCH v3 02/16] umh: Move setting PF_UMH into umh_pipe_setup Eric W. Biederman
2020-07-02 16:41 ` [PATCH v3 03/16] umh: Rename the user mode driver helpers for clarity Eric W. Biederman
2020-07-02 16:41 ` [PATCH v3 04/16] umh: Remove call_usermodehelper_setup_file Eric W. Biederman
2020-07-02 16:41 ` [PATCH v3 05/16] umh: Separate the user mode driver and the user mode helper support Eric W. Biederman
2020-07-02 16:41 ` [PATCH v3 06/16] umd: For clarity rename umh_info umd_info Eric W. Biederman
2020-07-02 16:41 ` [PATCH v3 07/16] umd: Rename umd_info.cmdline umd_info.driver_name Eric W. Biederman
2020-07-02 16:41 ` [PATCH v3 08/16] umd: Transform fork_usermode_blob into fork_usermode_driver Eric W. Biederman
2020-07-02 16:41 ` [PATCH v3 09/16] umh: Stop calling do_execve_file Eric W. Biederman
2020-07-02 16:41 ` [PATCH v3 10/16] exec: Remove do_execve_file Eric W. Biederman
2020-07-08 6:35 ` Luis Chamberlain
2020-07-08 12:41 ` Luis Chamberlain
2020-07-08 13:08 ` Eric W. Biederman
2020-07-08 13:32 ` Luis Chamberlain
2020-07-12 21:02 ` Pavel Machek
2020-07-02 16:41 ` [PATCH v3 11/16] bpfilter: Move bpfilter_umh back into init data Eric W. Biederman
2020-07-02 16:41 ` [PATCH v3 12/16] umd: Track user space drivers with struct pid Eric W. Biederman
2020-07-02 16:41 ` [PATCH v3 13/16] exit: Factor thread_group_exited out of pidfd_poll Eric W. Biederman
2020-07-03 20:30 ` Alexei Starovoitov
2020-07-03 21:37 ` Eric W. Biederman
2020-07-04 0:03 ` Alexei Starovoitov
2020-07-04 15:50 ` Christian Brauner
2020-07-07 17:09 ` Eric W. Biederman
2020-07-08 0:05 ` Daniel Borkmann
2020-07-08 3:50 ` Eric W. Biederman
2020-07-04 16:00 ` Christian Brauner
2020-07-02 16:41 ` [PATCH v3 14/16] bpfilter: Take advantage of the facilities of struct pid Eric W. Biederman
2020-07-02 16:41 ` [PATCH v3 15/16] umd: Remove exit_umh Eric W. Biederman
2020-07-02 16:41 ` [PATCH v3 16/16] umd: Stop using split_argv Eric W. Biederman
2020-07-02 23:51 ` [PATCH v3 00/16] Make the user mode driver code a better citizen Tetsuo Handa
2020-07-09 22:05 ` [merged][PATCH " Eric W. Biederman
2020-07-14 19:42 ` Alexei Starovoitov
2020-07-08 5:20 ` [PATCH v2 00/15] " Luis Chamberlain
2020-06-26 14:10 ` [PATCH 00/14] " Greg Kroah-Hartman
2020-06-26 16:40 ` Alexei Starovoitov
2020-06-26 17:17 ` Eric W. Biederman
2020-06-26 18:22 ` Alexei Starovoitov
2020-06-27 11:38 ` Tetsuo Handa
2020-06-27 12:59 ` Eric W. Biederman
2020-06-27 13:57 ` Tetsuo Handa
2020-06-28 19:44 ` Alexei Starovoitov
2020-06-29 2:20 ` Tetsuo Handa
2020-06-29 20:19 ` Eric W. Biederman
2020-06-30 6:28 ` Tetsuo Handa
2020-06-30 12:32 ` Eric W. Biederman
2020-06-30 16:48 ` Alexei Starovoitov
2020-06-30 21:54 ` Tetsuo Handa
2020-06-30 21:57 ` Alexei Starovoitov
2020-06-30 22:58 ` Tetsuo Handa
2020-06-25 12:56 ` [RFC][PATCH] net/bpfilter: Remove this broken and apparently unmantained Stephen Smalley
2020-06-25 13:25 ` Greg Kroah-Hartman
2020-06-25 14:26 ` Stephen Smalley
2020-06-25 14:36 ` Stephen Smalley
2020-06-25 15:21 ` Tetsuo Handa
2020-06-25 16:03 ` Stephen Smalley
2020-06-25 16:06 ` Casey Schaufler
2020-06-26 11:30 ` Eric W. Biederman
2020-06-07 5:58 ` Eric W. Biederman
2020-06-07 11:56 ` Eric W. Biederman
2020-06-08 16:35 ` Alexei Starovoitov
2020-06-08 16:33 ` Alexei Starovoitov
2020-06-06 20:43 ` Matthew Wilcox
2020-06-07 15:51 ` Eric W. Biederman
2020-06-07 1:13 ` Tetsuo Handa
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