linux-kernel - Re: [PATCH 0/3] ptrace: Stop supporting SIGKILL for PTRACE_EVENT

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Date:   Tue, 12 Jul 2022 15:03:04 -0500
From:   "Eric W. Biederman" <ebiederm@...ssion.com>
To:     Keno Fischer <keno@...iacomputing.com>
Cc:     Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        mingo@...nel.org,
        Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
        Peter Zijlstra <peterz@...radead.org>,
        Jann Horn <jannh@...gle.com>,
        Kees Cook <keescook@...omium.org>,
        Alexander Gordeev <agordeev@...ux.ibm.com>,
        "Robert O'Callahan" <roc@...nos.co>, Kyle Huey <khuey@...nos.co>,
        Oleg Nesterov <oleg@...hat.com>
Subject: Re: [PATCH 0/3] ptrace: Stop supporting SIGKILL for PTRACE_EVENT_EXIT

Keno Fischer <keno@...iacomputing.com> writes:

> Hi Eric,
>
> On Fri, Jul 8, 2022 at 6:25 PM Eric W. Biederman <ebiederm@...ssion.com> wrote:
>> > Recently I had a conversation where it was pointed out to me that
>> > SIGKILL sent to a tracee stropped in PTRACE_EVENT_EXIT is quite
>> > difficult for a tracer to handle.
>> >
>>
>> RR folks any comments?
>>
>> Did I properly understand what Keno Fischer was asking for when we
>> talked in person?
>
> Yes, this is indeed what I had in mind. I have not yet had the opportunity
> to try out your patch series (sorry), but from visual inspection, it does indeed
> do what I wanted, which is to make sure that a tracee stays in
> PTRACE_EVENT_EXIT for the tracer to inspect, even if there is another
> SIGKILL incoming simultaneously (since otherwise it may be impossible
> for the tracer to observe the PTRACE_EVENT_EXIT if two SIGKILLs
> come in rapid succession). I will try to take this series for a proper spin
> shortly.

Thanks,

I haven't yet figured out how to get the rr test suite to run
successfully.  Something about my test machine and lack of perf counters
seems to be causing problems.  So if you can perform the testing on your
side that would be fantastic.

Eric