Re: [PATCH bpf-next 2/2] selftests/bpf: Add tests for bpf_get_dentry_xattr

[Paul Moore <paul@paul-moore.com>]

On Tue, Aug 20, 2024 at 1:43 PM Song Liu <songliubraving@meta.com> wrote:
> > On Aug 20, 2024, at 5:45 AM, Mickaël Salaün <mic@digikod.net> wrote:

...

> > What about adding BPF hooks to Landlock?  User space could create
> > Landlock sandboxes that would delegate the denials to a BPF program,
> > which could then also allow such access, but without directly handling
> > nor reimplementing filesystem path walks.  The Landlock user space ABI
> > changes would mainly be a new landlock_ruleset_attr field to explicitly
> > ask for a (system-wide) BPF program to handle access requests if no
> > Landlock rule allow them.  We could also tie a BPF data (i.e. blob) to
> > Landlock domains for consistent sandbox management.  One of the
> > advantage of this approach is to only run related BPF programs if the
> > sandbox policy would deny the request.  Another advantage would be to
> > leverage the Landlock user space interface to let any program partially
> > define and extend their security policy.
>
> Given there is BPF LSM, I have never thought about adding BPF hooks to
> Landlock or other LSMs. I personally would prefer to have a common API
> to walk the path, maybe something like vma_iterator. But I need to read
> more code to understand whether this makes sense?

Just so there isn't any confusion, I want to make sure that everyone
is clear that "adding BPF hooks to Landlock" should mean "add a new
Landlock specific BPF hook inside Landlock" and not "reuse existing
BPF LSM hooks inside Landlock".

-- 
paul-moore.com