linux-kernel - Re: [RFC][PATCH 4/4] security: Enforce limitations on return values from LSMs

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Message-ID: <CAHC9VhRzzGt3N+AMxp93Zzq+1tWjd63hNv8AzZx4kppu2J535w@mail.gmail.com>
Date:   Wed, 16 Nov 2022 17:06:22 -0500
From:   Paul Moore <paul@...l-moore.com>
To:     Roberto Sassu <roberto.sassu@...weicloud.com>
Cc:     ast@...nel.org, daniel@...earbox.net, andrii@...nel.org,
        martin.lau@...ux.dev, song@...nel.org, yhs@...com,
        john.fastabend@...il.com, kpsingh@...nel.org, sdf@...gle.com,
        haoluo@...gle.com, jolsa@...nel.org, revest@...omium.org,
        jackmanb@...omium.org, jmorris@...ei.org, serge@...lyn.com,
        bpf@...r.kernel.org, linux-security-module@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Roberto Sassu <roberto.sassu@...wei.com>
Subject: Re: [RFC][PATCH 4/4] security: Enforce limitations on return values
 from LSMs

On Wed, Nov 16, 2022 at 9:37 AM Roberto Sassu
<roberto.sassu@...weicloud.com> wrote:
> On Tue, 2022-11-15 at 21:35 -0500, Paul Moore wrote:
> > If you want to somehow instrument the LSM hook definitions (what I
> > believe to be the motivation behind patch 3/4) to indicate valid
> > return values for use by the BPF verifier, I think we could entertain
> > that, or at least discuss it further, but I'm not inclined to support
> > any runtime overhead at the LSM layer for a specific LSM.
>
> Ok, yes. Patches 1-3 would help to keep in sync the LSM infrastructure
> and eBPF, but it is not strictly needed. I could propose an eBPF-only
> alternative to declare sets of functions per interval.
>
> More or less, I developed an eBPF-based alternative also for patch 4.
> It is just a proof of concept. Will propose it, to validate the idea.

Thanks, I think that might be the best approach.  Also, please
resubmit patches 1/4 and 2/4 with those small changes; those are nice
improvements that just need a couple of small tweaks to be acceptable
:)

-- 
paul-moore.com