Subject: Re: [PATCH/RFC net-next] rocker: forward packets to CPU when a port in promiscuous mode

From: Simon Horman <[email-masked]>
Date: Wed, 15 Jul 2015 13:45:23 +0900

Hi Scott,

On Mon, Jul 13, 2015 at 11:37:59PM -0700, Scott Feldman wrote:
> On Wed, Jul 8, 2015 at 9:25 PM, Simon Horman <[email-masked]> wrote:
> > This change allows the CPU to see all packets seen by a port when the
> > netdev associated with the port is in promiscuous mode.
> >
> > This change was previously posted as part of a larger patch and in turn
> > patchset which also aimed to allow rocker interfaces to receive packets
> > when not bridged. That problem has subsequently been addressed in a
> > different way by Scott Feldman.
> >
> > When this change was previously posted Scott indicated that he had some
> > reservations about sending all packets from a switch to the CPU. The
> > purpose of posting this patch is to start discussion of weather this
> > approach is appropriate and if not how else we might move forwards.
> >
> > In my opinion if host doesn't want all packets its shouldn't put a port
> > in promiscuous mode. But perhaps that is an overly naïve view to take.
> >
> > My main motivation for this change at this time is to allow rocker to
> > work with Open vSwitch and it appears that this change is sufficient to
> > reach that goal. Another approach might be to teach
> > rocker_port_master_changed() about Open vSwitch.
> >
> > In the longer term I believe Open vSwitch should be able to program
> > flows into rocker 'hardware' and thus not all packets would reach the CPU.
> 
> Hi Simon,
> 
> I like your alternate approach to teach rocker about Open vSwitch
> using rocker_port_master_change() and only when port is captured by
> OVS would we install the "promisc" filter to pass all traffic up.
> (Maybe call it ROCKER_CTRL_DFLT_OVS rule?).
> 
> Putting a non-bridged, non-ovs port into promisc is kind of weird for
> a switch port.  I think of the port in L3 mode by default, where the
> port is locked down for all but some selective mcasts, and only opened
> up by installing explicit routes.  (Unlike a bridged port where we
> flood everything L2 we don't understand).
> 
> So maybe first pass is to pass up everything when port is captured by
> OVS, and then later refine what's passed up per ovs flows on that
> port.

That sounds reasonable to me. Its pretty clear to me from the responses
from John and yourself that my approach to the promiscuous flag isn't
as clean-cut as I had hoped. And it seems that we have a nice way to
move forwards on supporting Open vSwitch.

How about this?

-- >8 --

From: Simon Horman <[email-masked]>

Subject: rocker: forward packets to CPU when port is joined to openvswitch

Teach rocker to forward packets to CPU when a port is joined to Open vSwitch.
There is scope to later refine what is passed up as per Open vSwitch flows
on a port.

This does not change the behaviour of rocker ports that are
not joined to Open vSwitch.

Signed-off-by: Simon Horman <[email-masked]>
---
 drivers/net/ethernet/rocker/rocker.c | 55 ++++++++++++++++++++++++++++++++----
 1 file changed, 49 insertions(+), 6 deletions(-)

diff --git a/drivers/net/ethernet/rocker/rocker.c b/drivers/net/ethernet/rocker/rocker.c
index c0051673c9fa..8c53d6839260 100644
--- a/drivers/net/ethernet/rocker/rocker.c
+++ b/drivers/net/ethernet/rocker/rocker.c
@@ -202,6 +202,7 @@ enum {
 	ROCKER_CTRL_IPV4_MCAST,
 	ROCKER_CTRL_IPV6_MCAST,
 	ROCKER_CTRL_DFLT_BRIDGING,
+	ROCKER_CTRL_DFLT_OVS,
 	ROCKER_CTRL_MAX,
 };
 
@@ -321,9 +322,21 @@ static u16 rocker_port_vlan_to_vid(const struct rocker_port *rocker_port,
 	return ntohs(vlan_id);
 }
 
+static bool rocker_port_is_bridged__(const struct rocker_port *rocker_port,
+				     const char *kind)
+{
+	return rocker_port->bridge_dev &&
+		!strcmp(rocker_port->bridge_dev->rtnl_link_ops->kind, kind);
+}
+
 static bool rocker_port_is_bridged(const struct rocker_port *rocker_port)
 {
-	return !!rocker_port->bridge_dev;
+	return rocker_port_is_bridged__(rocker_port, "bridge");
+}
+
+static bool rocker_port_is_ovs(const struct rocker_port *rocker_port)
+{
+	return rocker_port_is_bridged__(rocker_port, "openvswitch");
 }
 
 #define ROCKER_OP_FLAG_REMOVE		BIT(0)
@@ -3275,6 +3288,12 @@ static struct rocker_ctrl {
 		.bridge = true,
 		.copy_to_cpu = true,
 	},
+	[ROCKER_CTRL_DFLT_OVS] = {
+		/* pass all pkts up to CPU */
+		.eth_dst = zero_mac,
+		.eth_dst_mask = zero_mac,
+		.acl = true,
+	},
 };
 
 static int rocker_port_ctrl_vlan_acl(struct rocker_port *rocker_port,
@@ -3787,11 +3806,14 @@ static int rocker_port_stp_update(struct rocker_port *rocker_port,
 		break;
 	case BR_STATE_LEARNING:
 	case BR_STATE_FORWARDING:
-		want[ROCKER_CTRL_LINK_LOCAL_MCAST] = true;
+		if (!rocker_port_is_ovs(rocker_port))
+			want[ROCKER_CTRL_LINK_LOCAL_MCAST] = true;
 		want[ROCKER_CTRL_IPV4_MCAST] = true;
 		want[ROCKER_CTRL_IPV6_MCAST] = true;
 		if (rocker_port_is_bridged(rocker_port))
 			want[ROCKER_CTRL_DFLT_BRIDGING] = true;
+		else if (rocker_port_is_ovs(rocker_port))
+			want[ROCKER_CTRL_DFLT_OVS] = true;
 		else
 			want[ROCKER_CTRL_LOCAL_ARP] = true;
 		break;
@@ -5251,6 +5273,22 @@ static int rocker_port_bridge_leave(struct rocker_port *rocker_port)
 	return err;
 }
 
+
+static int rocker_port_ovs_changed(struct rocker_port *rocker_port,
+				   struct net_device *master)
+{
+	int err;
+
+	rocker_port->bridge_dev = master;
+
+	err = rocker_port_fwd_disable(rocker_port, SWITCHDEV_TRANS_NONE, 0);
+	if (err)
+		return err;
+	err = rocker_port_fwd_enable(rocker_port, SWITCHDEV_TRANS_NONE, 0);
+
+	return err;
+}
+
 static int rocker_port_master_changed(struct net_device *dev)
 {
 	struct rocker_port *rocker_port = netdev_priv(dev);
@@ -5263,11 +5301,16 @@ static int rocker_port_master_changed(struct net_device *dev)
 	 * 3. Other, e.g. being added to or removed from a bond or openvswitch,
 	 *    in which case nothing is done
 	 */
-	if (master && master->rtnl_link_ops &&
-	    !strcmp(master->rtnl_link_ops->kind, "bridge"))
-		err = rocker_port_bridge_join(rocker_port, master);
-	else if (rocker_port_is_bridged(rocker_port))
+	if (master && master->rtnl_link_ops) {
+		if (!strcmp(master->rtnl_link_ops->kind, "bridge"))
+			err = rocker_port_bridge_join(rocker_port, master);
+		else if (!strcmp(master->rtnl_link_ops->kind, "openvswitch"))
+			err = rocker_port_ovs_changed(rocker_port, master);
+	} else if (rocker_port_is_bridged(rocker_port)) {
 		err = rocker_port_bridge_leave(rocker_port);
+	} else if (rocker_port_is_ovs(rocker_port)) {
+		err = rocker_port_ovs_changed(rocker_port, NULL);
+	}
 
 	return err;
 }
-- 
2.1.4