linux-kernel - Re: [PATCH bpf-next 4/4] bpf: export bpf_jit

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]

Date:   Tue, 28 Sep 2021 10:02:32 +0100
From:   Lorenz Bauer <lmb@...udflare.com>
To:     Jakub Sitnicki <jakub@...udflare.com>
Cc:     Daniel Borkmann <daniel@...earbox.net>,
        Alexei Starovoitov <ast@...nel.org>,
        Andrii Nakryiko <andrii@...nel.org>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        kernel-team <kernel-team@...udflare.com>,
        Networking <netdev@...r.kernel.org>, bpf <bpf@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH bpf-next 4/4] bpf: export bpf_jit_current

On Mon, 27 Sept 2021 at 15:01, Jakub Sitnicki <jakub@...udflare.com> wrote:
>
> I find exposing stats via system configuration variables a bit
> unexpected. Not sure if there is any example today that we're following.
>
> Maybe an entry under /sys/kernel/debug would be a better fit?
>
> That way we don't have to commit to a sysctl that might go away if we
> start charging JIT allocs against memory cgroup quota.

I had a look around, there are no other obvious places in debugfs or
proc where we already have bpf info exposed. It currently all goes via
sysctl.

There are examples of readonly sysctls:
$ sudo find /proc/sys -perm 0444 | wc -l
90

There are no examples of sysctls with mode 0400 however:
$ sudo find /proc/sys -perm 0400 | wc -l
0

I find it kind of weird that the bpf sysctls are so tightly locked
down (CAP_SYS_ADMIN && root) even for reading. Maybe something I can
change?

-- 
Lorenz Bauer  |  Systems Engineer
6th Floor, County Hall/The Riverside Building, SE1 7PB, UK

www.cloudflare.com