From: Alexander Popov <alex.popov@linux.com>
To: Kees Cook <keescook@chromium.org>,
Dave Hansen <dave.hansen@intel.com>,
Peter Zijlstra <peterz@infradead.org>
Cc: Jonathan Corbet <corbet@lwn.net>,
Paul McKenney <paulmck@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Thomas Gleixner <tglx@linutronix.de>,
Joerg Roedel <jroedel@suse.de>,
Maciej Rozycki <macro@orcam.me.uk>,
Muchun Song <songmuchun@bytedance.com>,
Viresh Kumar <viresh.kumar@linaro.org>,
Robin Murphy <robin.murphy@arm.com>,
Randy Dunlap <rdunlap@infradead.org>,
Lu Baolu <baolu.lu@linux.intel.com>,
Petr Mladek <pmladek@suse.com>,
Luis Chamberlain <mcgrof@kernel.org>, Wei Liu <wl@xen.org>,
John Ogness <john.ogness@linutronix.de>,
Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
Alexey Kardashevskiy <aik@ozlabs.ru>,
Christophe Leroy <christophe.leroy@csgroup.eu>,
Jann Horn <jannh@google.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Mark Rutland <mark.rutland@arm.com>,
Andy Lutomirski <luto@kernel.org>,
Dave Hansen <dave.hansen@linux.intel.com>,
Steven Rostedt <rostedt@goodmis.org>,
Will Deacon <will.deacon@arm.com>,
David S Miller <davem@davemloft.net>,
Borislav Petkov <bp@alien8.de>,
kernel-hardening@lists.openwall.com,
linux-hardening@vger.kernel.org, linux-doc@vger.kernel.org,
linux-kernel@vger.kernel.org, notify@kernel.org
Subject: Re: [PATCH] Introduce the pkill_on_warn boot parameter
Date: Thu, 30 Sep 2021 16:55:37 +0300 [thread overview]
Message-ID: <cf6ada34-9854-b7ad-f671-52186da5abd0@linux.com> (raw)
In-Reply-To: <202109291229.C64A1D9D@keescook>
On 29.09.2021 23:06, Kees Cook wrote:
> On Wed, Sep 29, 2021 at 12:03:36PM -0700, Dave Hansen wrote:
>> On 9/29/21 11:58 AM, Alexander Popov wrote:
>>> --- a/kernel/panic.c
>>> +++ b/kernel/panic.c
>>> @@ -53,6 +53,7 @@ static int pause_on_oops_flag;
>>> static DEFINE_SPINLOCK(pause_on_oops_lock);
>>> bool crash_kexec_post_notifiers;
>>> int panic_on_warn __read_mostly;
>>> +int pkill_on_warn __read_mostly;
>
> I like this idea. I can't tell if Linus would tolerate it, though. But I
> really have wanted a middle ground like BUG(). Having only WARN() and
> panic() is not very friendly. :(
Ok, let's see.
Kees, could you also share your thoughts on the good questions by Petr Mladek in
this thread?
>>> unsigned long panic_on_taint;
>>> bool panic_on_taint_nousertaint = false;
>>>
>>> @@ -610,6 +611,9 @@ void __warn(const char *file, int line, void *caller, unsigned taint,
>>>
>>> print_oops_end_marker();
>>>
>>> + if (pkill_on_warn && system_state >= SYSTEM_RUNNING)
>>> + do_group_exit(SIGKILL);
>>> +
>>> /* Just a warning, don't kill lockdep. */
>>> add_taint(taint, LOCKDEP_STILL_OK);
>>> }
>>
>> Doesn't this tie into the warning *printing* code? That's better than
>> nothing, for sure. But, if we're doing this for hardening, I think we
>> would want to kill anyone provoking a warning, not just the first one
>> that triggered *printing* the warning.
>
> Right, this needs to be moved into the callers of __warn() (i.e.
> report_bug(), and warn_slowpath_fmt()), likely with some small
> refactoring in report_bug().
Yes, I see now. Thanks, Dave, Peter and Kees.
The kernel can hit warning and omit calling __warn() that prints the message.
But pkill_on_warn action should be taken each time.
As I can understand now, include/asm-generic/bug.h defines three warning
implementations:
1. CONFIG_BUG=y and the arch provides __WARN_FLAGS. In that case pkill_on_warn
should be checked in report_bug() that you mention.
2. CONFIG_BUG=y and the arch doesn't have __WARN_FLAGS. In that case
pkill_on_warn should be checked in warn_slowpath_fmt().
3. CONFIG_BUG is not set. In that case pkill_on_warn should not be considered.
Please, correct me if needed.
Best regards,
Alexander
next prev parent reply other threads:[~2021-09-30 13:55 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-29 18:58 [PATCH] Introduce the pkill_on_warn boot parameter Alexander Popov
2021-09-29 19:01 ` Alexander Popov
2021-09-29 19:49 ` Paul E. McKenney
2021-09-30 9:15 ` Petr Mladek
2021-09-30 15:05 ` Alexander Popov
2021-10-01 12:23 ` Petr Mladek
2021-09-30 16:59 ` Steven Rostedt
2021-10-01 12:09 ` Petr Mladek
2021-09-30 18:28 ` Kees Cook
2021-10-01 19:59 ` Linus Torvalds
2021-10-02 11:41 ` Alexander Popov
2021-10-02 12:13 ` Steven Rostedt
2021-10-02 16:33 ` Alexander Popov
2021-10-02 16:52 ` Linus Torvalds
2021-10-02 21:05 ` Alexander Popov
2021-10-05 19:48 ` Eric W. Biederman
2021-10-06 14:56 ` Alexander Popov
2021-10-22 17:30 ` Alexander Popov
2022-07-27 16:17 ` Alexey Khoroshilov
2022-07-27 16:30 ` Jann Horn
2022-07-27 16:43 ` Alexey Khoroshilov
2022-07-27 16:42 ` Linus Torvalds
2022-07-27 17:47 ` Alexey Khoroshilov
2021-09-29 23:31 ` Andrew Morton
2021-09-30 18:27 ` Alexander Popov
2021-09-30 18:36 ` Kees Cook
2021-09-29 19:03 ` Dave Hansen
2021-09-29 19:47 ` Peter Zijlstra
2021-09-29 20:06 ` Kees Cook
2021-09-30 13:55 ` Alexander Popov [this message]
2021-09-30 18:20 ` Kees Cook
2021-10-02 18:04 ` Al Viro
2021-10-02 18:31 ` Steven Rostedt
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