linux-kernel - Re: [RFC PATCH bpf-next 2/4] bpf: add BPF_F_DESTRUCTIVE flag for BPF_PROG

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Message-ID: <YswOIzI7urHs4XBi@samus.usersys.redhat.com>
Date:   Mon, 11 Jul 2022 13:48:51 +0200
From:   Artem Savkov <asavkov@...hat.com>
To:     Jiri Olsa <olsajiri@...il.com>
Cc:     Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Andrii Nakryiko <andrii@...nel.org>, bpf@...r.kernel.org,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        Andrea Arcangeli <aarcange@...hat.com>
Subject: Re: [RFC PATCH bpf-next 2/4] bpf: add BPF_F_DESTRUCTIVE flag for
 BPF_PROG_LOAD

On Mon, Jul 11, 2022 at 12:56:28PM +0200, Jiri Olsa wrote:
> On Mon, Jul 11, 2022 at 10:32:18AM +0200, Artem Savkov wrote:
> > Add a BPF_F_DESTRUCTIVE will be required to be supplied to
> > BPF_PROG_LOAD for programs to utilize destructive helpers such as
> > bpf_panic().
> 
> I'd think that having kernel.destructive_bpf_enabled sysctl knob enabled
> would be enough to enable that helper from any program, not sure having
> extra load flag adds more security

I agree it doesn't add more security. The idea was to have a way for a
developer to explicitly state he understand this will be dangerous. This
flag can also translate well into something like a --destructive option
for bpftrace without needing to keep a list of destructive helpers on
their side.

-- 
 Artem