Re: [PATCH v2 0/4] Firmware LSM hook

Jason Gunthorpe
2026-04-13T16:42:22Z

On Sun, Apr 12, 2026 at 09:38:35PM -0400, Paul Moore wrote:
> > We are not limited to LSM solution, the goal is to intercept commands
> > which are submitted to the FW and "security" bucket sounded right to us.
>
> Yes, it does sound "security relevant", but without a well defined
> interface/format it is going to be difficult to write a generic LSM to
> have any level of granularity beyond a basic "load firmware"
> permission.

I think to step back a bit, what this is trying to achieve is very
similar to the iptables fwmark/secmark scheme.

secmark allows the user to specify programmable rules via iptables
which results in each packet being tagged with a SELinux context and
then the userspace policy can consume that and make security decision
based on that.

Google is showing me examples of this to permit only certain processes
to use certain network addresses.

So this is exactly the same high level idea. The transport of the
packet is different (firwmare cmd vs network) but otherwise it is all
the same basic problem. We need a user programmable classifier like
iptables. Once classified we want this to work with more than SELinux
only, we have a particular interest in the eBPF LSM. In any case the
userspace should be able to specify the security policy that applies
to the kernel classified data.

Following the fwmark example, if there was some programmable in-kernel
function to convert the cmd into a SELinux label would we be able to
enable SELinux following the SECMARK design?

Would there be an objection if that in-kernel function was using a
system-wide eBPF uploaded with some fwctl uAPI?

Finally, would there be an objection to enabling the same function in
eBPF by feeding it the entire command and have it classify and make a
security decision in a single eBPF program? Is there some other way to
enable eBPF? I see eBPF doesn't interwork with SECMARK today so there
isn't a ready example?

Jason