linux-kernel - Re: [PATCH v4] signal: add taskfd_send

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <87pnue6bp2.fsf@oldenburg2.str.redhat.com>
Date:   Thu, 06 Dec 2018 14:12:41 +0100
From:   Florian Weimer <fweimer@...hat.com>
To:     Jürg Billeter <j@...ron.ch>
Cc:     Christian Brauner <christian@...uner.io>,
        linux-kernel@...r.kernel.org, linux-api@...r.kernel.org,
        luto@...nel.org, arnd@...db.de, ebiederm@...ssion.com,
        serge@...lyn.com, jannh@...gle.com, akpm@...ux-foundation.org,
        oleg@...hat.com, cyphar@...har.com, viro@...iv.linux.org.uk,
        linux-fsdevel@...r.kernel.org, dancol@...gle.com,
        timmurray@...gle.com, linux-man@...r.kernel.org,
        keescook@...omium.org, tglx@...utronix.de, x86@...nel.org
Subject: Re: [PATCH v4] signal: add taskfd_send_signal() syscall

* Jürg Billeter:

> On Thu, 2018-12-06 at 13:30 +0100, Florian Weimer wrote:
>> * Christian Brauner:
>> 
>> > /* zombies */
>> > Zombies can be signaled just as any other process. No special error will be
>> > reported since a zombie state is an unreliable state (cf. [3]).
>> 
>> I still disagree with this analysis.  If I know that the target process
>> is still alive, and it is not, this is a persistent error condition
>> which can be reliably reported.  Given that someone might send SIGKILL
>> to the process behind my back, detecting this error condition could be
>> useful.
>
> As I understand it, kill() behaves the same way. I think it's good that
> this new syscall keeps the behavior as close as possible to kill().

No, kill does not behave in this way because the PID can be reused.
The error condition is not stable there.

Thanks,
Florian