netdev - Re: [PATCH HID for-next v3 1/5] bpf: do not rely on ALLOW_ERROR_INJECTION for fmod

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Date:   Wed, 7 Dec 2022 15:57:01 +0100
From:   Benjamin Tissoires <benjamin.tissoires@...hat.com>
To:     Alexei Starovoitov <alexei.starovoitov@...il.com>
Cc:     Jiri Kosina <jikos@...nel.org>,
        Florent Revest <revest@...omium.org>,
        Jon Hunter <jonathanh@...dia.com>,
        Daniel Borkmann <daniel@...earbox.net>,
        Andrii Nakryiko <andrii@...nel.org>, bpf <bpf@...r.kernel.org>,
        Network Development <netdev@...r.kernel.org>,
        "open list:HID CORE LAYER" <linux-input@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH HID for-next v3 1/5] bpf: do not rely on
 ALLOW_ERROR_INJECTION for fmod_ret

On Tue, Dec 6, 2022 at 9:48 PM Alexei Starovoitov
<alexei.starovoitov@...il.com> wrote:
>
> On Tue, Dec 6, 2022 at 6:59 AM Benjamin Tissoires
> <benjamin.tissoires@...hat.com> wrote:
> >
> > The current way of expressing that a non-bpf kernel component is willing
> > to accept that bpf programs can be attached to it and that they can change
> > the return value is to abuse ALLOW_ERROR_INJECTION.
> > This is debated in the link below, and the result is that it is not a
> > reasonable thing to do.
> >
> > Reuse the kfunc declaration structure to also tag the kernel functions
> > we want to be fmodret. This way we can control from any subsystem which
> > functions are being modified by bpf without touching the verifier.
> >
> >
> > Link: https://lore.kernel.org/all/20221121104403.1545f9b5@gandalf.local.home/
> > Suggested-by: Alexei Starovoitov <alexei.starovoitov@...il.com>
> > Signed-off-by: Benjamin Tissoires <benjamin.tissoires@...hat.com>
>
> BPF CI couldn't do its job because of a merge conflict.
> CI only tries to apply the whole series.
> But I tested the patch 1 manually.
> Everything is green on x86-64 and the patch looks good.
>
> Acked-by: Alexei Starovoitov <ast@...nel.org>
>
> Please send the set during the merge window.
> If not we can take just this patch,
> since the series from Viktor Malik would need this patch too.
>

Thanks a lot for the quick review/tests Alexei.

I have now taken this patch and the next into the hid tree.

I actually took this patch through a branch attached to our hid.git
master branch so compared to Linus, it only has this one patch. I also
tagged (and signed) that very same branch with "for-alexei-2022120701"
in case you also want to bring this one in through the bpf tree too.

Full path is at
https://git.kernel.org/pub/scm/linux/kernel/git/hid/hid.git/tree/?h=for-alexei-2022120701

Cheers,
Benjamin