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Message-ID: <CAADnVQ+Twio22VSi21RR5TY1Zm-1xRTGmREcXLSs5Jv-KWGTiw@mail.gmail.com>
Date: Tue, 25 Jun 2019 16:02:57 -0700
From: Alexei Starovoitov <alexei.starovoitov@...il.com>
To: Mickaël Salaün <mic@...ikod.net>
Cc: LKML <linux-kernel@...r.kernel.org>,
Aleksa Sarai <cyphar@...har.com>,
Alexander Viro <viro@...iv.linux.org.uk>,
Alexei Starovoitov <ast@...nel.org>,
Andrew Morton <akpm@...ux-foundation.org>,
Andy Lutomirski <luto@...capital.net>,
Arnaldo Carvalho de Melo <acme@...nel.org>,
Casey Schaufler <casey@...aufler-ca.com>,
Daniel Borkmann <daniel@...earbox.net>,
David Drysdale <drysdale@...gle.com>,
"David S . Miller" <davem@...emloft.net>,
"Eric W . Biederman" <ebiederm@...ssion.com>,
James Morris <jmorris@...ei.org>, Jann Horn <jann@...jh.net>,
John Johansen <john.johansen@...onical.com>,
Jonathan Corbet <corbet@....net>,
Kees Cook <keescook@...omium.org>,
Michael Kerrisk <mtk.manpages@...il.com>,
Mickaël Salaün <mickael.salaun@....gouv.fr>,
Paul Moore <paul@...l-moore.com>,
Sargun Dhillon <sargun@...gun.me>,
"Serge E . Hallyn" <serge@...lyn.com>,
Shuah Khan <shuah@...nel.org>,
Stephen Smalley <sds@...ho.nsa.gov>, Tejun Heo <tj@...nel.org>,
Tetsuo Handa <penguin-kernel@...ove.sakura.ne.jp>,
Thomas Graf <tgraf@...g.ch>, Tycho Andersen <tycho@...ho.ws>,
Will Drewry <wad@...omium.org>,
Kernel Hardening <kernel-hardening@...ts.openwall.com>,
Linux API <linux-api@...r.kernel.org>,
Linux-Fsdevel <linux-fsdevel@...r.kernel.org>,
LSM List <linux-security-module@...r.kernel.org>,
Network Development <netdev@...r.kernel.org>
Subject: Re: [PATCH bpf-next v9 02/10] bpf: Add eBPF program subtype and
is_valid_subtype() verifier
On Tue, Jun 25, 2019 at 3:04 PM Mickaël Salaün <mic@...ikod.net> wrote:
>
> The goal of the program subtype is to be able to have different static
> fine-grained verifications for a unique program type.
>
> The struct bpf_verifier_ops gets a new optional function:
> is_valid_subtype(). This new verifier is called at the beginning of the
> eBPF program verification to check if the (optional) program subtype is
> valid.
>
> The new helper bpf_load_program_xattr() enables to verify a program with
> subtypes.
>
> For now, only Landlock eBPF programs are using a program subtype (see
> next commits) but this could be used by other program types in the
> future.
>
> Signed-off-by: Mickaël Salaün <mic@...ikod.net>
> Cc: Alexei Starovoitov <ast@...nel.org>
> Cc: Daniel Borkmann <daniel@...earbox.net>
> Cc: David S. Miller <davem@...emloft.net>
> Link: https://lkml.kernel.org/r/20160827205559.GA43880@ast-mbp.thefacebook.com
> ---
>
> Changes since v8:
> * use bpf_load_program_xattr() instead of bpf_load_program() and add
> bpf_verify_program_xattr() to deal with subtypes
> * remove put_extra() since there is no more "previous" field (for now)
>
> Changes since v7:
> * rename LANDLOCK_SUBTYPE_* to LANDLOCK_*
> * move subtype in bpf_prog_aux and use only one bit for has_subtype
> (suggested by Alexei Starovoitov)
sorry to say, but I don't think the landlock will ever land,
since posting huge patches once a year is missing a lot of development
that is happening during that time.
This 2/10 patch is an example.
subtype concept was useful 2 years ago when v6 was posted.
Since then bpf developers faced very similar problem in other parts
and it was solved with 'expected_attach_type' field.
See commit 5e43f899b03a ("bpf: Check attach type at prog load time")
dated March 2018.
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