Framework for hardware filter support?

[Daniel Santos <daniel.santos@pobox.com>]

Hello.  I'm doing a project where hardware filters will pretty much be
required unless we change the hardware.  I can just hack up the mcp251x
driver and add some sysfs nodes to modify the filters, but it would be
much nicer to implement using some type of standard framework that I
could submit back upstream.

My current project uses an MCP2515 (with only two rx buffers) connected
via an MCP2210 USB-to-SPI bridge and that introduces a lot of latency
and interrupts may not be serviced for as much as 20-30 ms and w/o
hardware filters, we'll be missing a lot of messages we want to sniff.

I've read some of the arguments against it, such is it being a
multi-user environment.  To me that just means that hardware filters
should be configured at the interface level and not at the socket level.

So is there no such framework already in place?  If not, where would be
the most logical place to add it? netfilter in the kernel and iproute2
in userland?

Thanks,
Daniel