linux-kernel - Re: [PATCH bpf-next 1/4] bpf: add BPF_F_DESTRUCTIVE flag for BPF_PROG

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Message-ID: <CAADnVQ+mt1iEsXUGBeL-dgXRoRwPxoz+G=aRcZTkhx2AA10R-A@mail.gmail.com>
Date:   Thu, 21 Jul 2022 07:02:07 -0700
From:   Alexei Starovoitov <alexei.starovoitov@...il.com>
To:     Artem Savkov <asavkov@...hat.com>
Cc:     Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Andrii Nakryiko <andrii@...nel.org>, bpf <bpf@...r.kernel.org>,
        Network Development <netdev@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Andrea Arcangeli <aarcange@...hat.com>,
        Daniel Vacek <dvacek@...hat.com>,
        Jiri Olsa <olsajiri@...il.com>, Song Liu <song@...nel.org>
Subject: Re: [PATCH bpf-next 1/4] bpf: add BPF_F_DESTRUCTIVE flag for BPF_PROG_LOAD

On Wed, Jul 20, 2022 at 4:47 AM Artem Savkov <asavkov@...hat.com> wrote:
>
> +/* If BPF_F_DESTRUCTIVE is used in BPF_PROG_LOAD command, the loaded program
> + * will be able to perform destructive operations such as calling bpf_panic()
> + * helper.
> + */
> +#define BPF_F_DESTRUCTIVE      (1U << 6)

I don't understand what value this flag provides.

bpf prog won't be using kexec accidentally.
Requiring user space to also pass this flag seems pointless.