From: Kees Cook <keescook@chromium.org>
To: Paul Moore <paul@paul-moore.com>
Cc: KP Singh <kpsingh@kernel.org>,
linux-security-module@vger.kernel.org, bpf@vger.kernel.org,
ast@kernel.org, daniel@iogearbox.net, jackmanb@google.com,
renauld@google.com, casey@schaufler-ca.com, song@kernel.org,
revest@chromium.org
Subject: Re: [PATCH bpf-next 0/4] Reduce overhead of LSMs with static calls
Date: Thu, 9 Feb 2023 08:56:07 -0800 [thread overview]
Message-ID: <63e525a8.170a0220.e8217.2fdb@mx.google.com> (raw)
In-Reply-To: <CAHC9VhRpsXME9Wht_RuSACuU97k359dihye4hW15nWwSQpxtng@mail.gmail.com>
On Fri, Jan 27, 2023 at 03:16:38PM -0500, Paul Moore wrote:
> On Thu, Jan 19, 2023 at 6:10 PM KP Singh <kpsingh@kernel.org> wrote:
> >
> > # Background
> >
> > LSM hooks (callbacks) are currently invoked as indirect function calls. These
> > callbacks are registered into a linked list at boot time as the order of the
> > LSMs can be configured on the kernel command line with the "lsm=" command line
> > parameter.
>
> Thanks for sending this KP. I had hoped to make a proper pass through
> this patchset this week but I ended up getting stuck trying to wrap my
> head around some network segmentation offload issues and didn't quite
> make it here. Rest assured it is still in my review queue.
>
> However, I did manage to take a quick look at the patches and one of
> the first things that jumped out at me is it *looks* like this
> patchset is attempting two things: fix a problem where one LSM could
> trample another (especially problematic with the BPF LSM due to its
> nature), and reduce the overhead of making LSM calls. I realize that
> in this patchset the fix and the optimization are heavily
> intermingled, but I wonder what it would take to develop a standalone
> fix using the existing indirect call approach? I'm guessing that is
> going to potentially be a pretty significant patch, but if we could
> add a little standardization to the LSM hooks without adding too much
> in the way of code complexity or execution overhead I think that might
> be a win independent of any changes to how we call the hooks.
>
> Of course this could be crazy too, but I'm the guy who has to ask
> these questions :)
Hm, I am expecting this patch series to _not_ change any semantics of
the LSM "stack". I would agree: nothing should change in this series, as
it should be strictly a mechanical change from "iterate a list of
indirect calls" to "make a series of direct calls". Perhaps I missed
a logical change?
--
Kees Cook
next prev parent reply other threads:[~2023-02-09 16:56 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-01-19 23:10 [PATCH bpf-next 0/4] Reduce overhead of LSMs with static calls KP Singh
2023-01-19 23:10 ` [PATCH bpf-next 1/4] kernel: Add helper macros for loop unrolling KP Singh
2023-01-19 23:10 ` [PATCH bpf-next 2/4] security: Generate a header with the count of enabled LSMs KP Singh
2023-01-20 1:32 ` Casey Schaufler
2023-01-20 2:15 ` KP Singh
2023-01-20 18:35 ` Kui-Feng Lee
2023-01-20 19:40 ` Kees Cook
2023-01-19 23:10 ` [PATCH bpf-next 3/4] security: Replace indirect LSM hook calls with static calls KP Singh
2023-01-20 1:43 ` Casey Schaufler
2023-01-20 2:13 ` KP Singh
2023-01-19 23:10 ` [PATCH bpf-next 4/4] bpf: Only enable BPF LSM hooks when an LSM program is attached KP Singh
2023-01-20 1:13 ` [PATCH bpf-next 0/4] Reduce overhead of LSMs with static calls Casey Schaufler
2023-01-20 2:17 ` KP Singh
2023-01-20 18:40 ` Casey Schaufler
2023-01-27 19:22 ` Song Liu
2023-01-27 20:16 ` Paul Moore
2023-02-09 16:56 ` Kees Cook [this message]
2023-02-10 20:03 ` Paul Moore
2023-02-11 2:32 ` Casey Schaufler
2023-02-12 22:00 ` Paul Moore
2023-02-13 18:04 ` Casey Schaufler
2023-02-13 18:29 ` Casey Schaufler
2023-06-13 22:02 ` KP Singh
2023-06-20 23:40 ` Paul Moore
2023-07-26 11:07 ` Paolo Abeni
2023-09-16 0:57 ` KP Singh
2023-09-16 8:06 ` Paolo Abeni
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