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Subject: Re: [PATCH v2] signal: add procfd_signal() syscall
To:     Andy Lutomirski <luto@kernel.org>
CC:     Arnd Bergmann <arnd@arndb.de>,
        Daniel Colascione <dancol@google.com>,
        Andrew Lutomirski <luto@kernel.org>,
        "Eric W. Biederman" <ebiederm@xmission.com>,
        Florian Weimer <fweimer@redhat.com>,
        LKML <linux-kernel@vger.kernel.org>,
        "Serge E. Hallyn" <serge@hallyn.com>, Jann Horn <jannh@google.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Oleg Nesterov <oleg@redhat.com>,
        Aleksa Sarai <cyphar@cyphar.com>,
        Al Viro <viro@zeniv.linux.org.uk>,
        Linux FS Devel <linux-fsdevel@vger.kernel.org>,
        Linux API <linux-api@vger.kernel.org>,
        Tim Murray <timmurray@google.com>,
        linux-man <linux-man@vger.kernel.org>,
        Kees Cook <keescook@chromium.org>
From:   Christian Brauner <christian@brauner.io>
Message-ID: <F9EBD99D-0339-4AD6-B89B-84F164454336@brauner.io>
Sender: linux-kernel-owner@vger.kernel.org
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On December 1, 2018 12:46:22 PM GMT+13:00, Andy Lutomirski <luto@kernel=2Eo=
rg> wrote:
>On Fri, Nov 30, 2018 at 3:40 PM Christian Brauner
><christian@brauner=2Eio> wrote:
>>
>> On December 1, 2018 12:12:53 PM GMT+13:00, Arnd Bergmann
><arnd@arndb=2Ede> wrote:
>> >On Sat, Dec 1, 2018 at 12:05 AM Daniel Colascione
><dancol@google=2Ecom>
>> >wrote:
>> >> On Fri, Nov 30, 2018 at 2:26 PM Christian Brauner
>> ><christian@brauner=2Eio> wrote:
>> >> > On December 1, 2018 11:09:58 AM GMT+13:00, Arnd Bergmann
>> ><arnd@arndb=2Ede> wrote:
>> >> >
>> >> > One humble point I would like to make is that what I care about
>> >most is a sensible way forward without having to redo essential
>parts
>> >of how syscalls work=2E
>> >> > I don't want to introduce a sane, small syscall that ends up
>> >breaking all over the place because we decided to fix past mistakes
>> >that technically have nothing to do with the patch itself=2E
>> >> > However, I do sympathize and understand these concerns=2E
>> >>
>> >> IMHO, it's fine to just replicate all the splits we have for the
>> >> existing signal system calls=2E It's ugly, but once it's done, it'll
>be
>> >> done for a long time=2E I can't see a need to add even more signal
>> >> system calls after this one=2E
>> >
>> >We definitely need waitid_time64() and rt_sigtimedwait_time64()
>> >in the very near future=2E
>>
>> Right, I remember you pointing this out in a prior mail=2E
>> Thanks for working on this for such a long time now, Arnd!
>> Can we agree to move on with the procfd syscall given the current
>constraints?
>> I just don't want to see the syscall being
>> blocked by a generic problem whose
>> ultimate solution is to get rid of weird
>> architectural constraints=2E
>
>Creating and using a copy_siginfo_from_user64() function would work
>for everyone, no?

Meaning, no compat syscalls, introduce=20
new struct siginfo64_t and the copy=20
function you named above?