Message-Id: <1257535875.2610.15.camel@ppwaskie-mobl2>
Date:	Fri, 06 Nov 2009 11:31:15 -0800
From:	Peter P Waskiewicz Jr <peter.p.waskiewicz.jr@...el.com>
To:	Caitlin Bestler <caitlin.bestler@...il.com>
Cc:	"netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: Re: RFC: ethtool support for n-tuple filter programming

On Fri, 2009-11-06 at 11:12 -0800, Caitlin Bestler wrote:
> The approach you are proposing assumes what type of packet filters
> that L2 hardware could support.
> 
> Why not simply use existing filtering rules that overshoot the target,
> such as netfilter, and ask the
> device specific tool to indicate what set of these rules it can support?

Are you proposing that netfilter is modified to pass the filters down to
the hardware if it supports it?  netfilter doesn't steer flows though to
queues (or flow ID's in the kernel), plus that's putting HW-specific
capabilities into netfilter.  I'm not sure we want to do that.

Please correct me if I'm wrong with interpreting your suggestion.

Thanks,
-PJ

> 
> 
> On Fri, Nov 6, 2009 at 10:57 AM, Peter P Waskiewicz Jr
> <peter.p.waskiewicz.jr@...el.com> wrote:
> > All,
> >
> > I'm looking to add support to ethtool that would allow programming of
> > full n-tuple filters into underlying devices.  Currently, ixgbe has
> > support for these types of perfect match or mostly match (masked)
> > filters.  I imagine other hardware exists that also has support for
> > this, so I'd like to make this interface usable for everyone.
> >
> > Note that this is similar behavior in the iproute2 tools, but it's
> > different enough, in my opinion, to warrant being in ethtool.  The
> > iproute2 tools (specifically tc) manipulate the qdiscs to add filters in
> > the kernel packet schedulers.  This proposed solution is managing the
> > hardware in the underlying device, which iproute2 tools currently don't
> > touch.  Hopefully this is obvious for those reviewing this proposal.
> >
> > What I currently have as possible inputs to ethtool are:
> >
> > - src/dst IP address: 32-bits each, 128-bits each for IPv6
> > - src/dst port: 16-bits each (TCP/UDP)
> > - VLAN tag: 15-bits
> > - L4 type: 8-bits (TCP/UDP/SCTP currently, can grow later)
> > - User specified field: currently 32-bits, can be anything a driver
> > wants to use
> > - Action: signed 16-bits (-1 indicates drop, any other value is the Rx
> > queue to steer the flow to)
> >
> > Now all of these fields, except action, can also have a mask supplied to
> > them, but it's not mandatory.
> >
> > An example ethtool command with this support could be:
> >
> > # ethtool -F ethX dst-ip 0x0101a8c0 src-ip 0x0001a8c0 0x00ffffff
> > dst-port 0x1600 src-port 0x0000 0x0000 usr 0x8906 act 5
> >
> > This will program a filter that will filter traffic coming from
> > 192.168.1.0/24 to 192.168.1.1, port 22, from any source port, and will
> > place all those matches packets into Rx queue 5.  It also specified a
> > user-defined field of 0x8906, which a driver can use at its own
> > discretion (or omit completely).
> >
> > Then running the ethtool -f ethX command could dump all currently
> > programmed filters.
> >
> > Any comments, thoughts, suggestions, or ideas are welcome.
> >
> > Cheers,
> > -PJ Waskiewicz
> >
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