Commit ec7328b5 authored by Tobias Waldekranz's avatar Tobias Waldekranz Committed by Jakub Kicinski
Browse files

net: bridge: mst: Multiple Spanning Tree (MST) mode 



Allow the user to switch from the current per-VLAN STP mode to an MST
mode.

Up to this point, per-VLAN STP states where always isolated from each
other. This is in contrast to the MSTP standard (802.1Q-2018, Clause
13.5), where VLANs are grouped into MST instances (MSTIs), and the
state is managed on a per-MSTI level, rather that at the per-VLAN
level.

Perhaps due to the prevalence of the standard, many switching ASICs
are built after the same model. Therefore, add a corresponding MST
mode to the bridge, which we can later add offloading support for in a
straight-forward way.

For now, all VLANs are fixed to MSTI 0, also called the Common
Spanning Tree (CST). That is, all VLANs will follow the port-global
state.

Upcoming changes will make this actually useful by allowing VLANs to
be mapped to arbitrary MSTIs and allow individual MSTI states to be
changed.

Signed-off-by: default avatarTobias Waldekranz <tobias@waldekranz.com>
Acked-by: default avatarNikolay Aleksandrov <razor@blackwall.org>
Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent 54744510

include/uapi/linux/if_bridge.h

+1 −0
Original line number Diff line number Diff line
@@ -759,6 +759,7 @@ struct br_mcast_stats { 
enum br_boolopt_id {

	BR_BOOLOPT_NO_LL_LEARN,

	BR_BOOLOPT_MCAST_VLAN_SNOOPING,

	BR_BOOLOPT_MST_ENABLE,

	BR_BOOLOPT_MAX

};

net/bridge/Makefile

+1 −1
Original line number Diff line number Diff line
@@ -20,7 +20,7 @@ obj-$(CONFIG_BRIDGE_NETFILTER) += br_netfilter.o 


bridge-$(CONFIG_BRIDGE_IGMP_SNOOPING) += br_multicast.o br_mdb.o br_multicast_eht.o



bridge-$(CONFIG_BRIDGE_VLAN_FILTERING) += br_vlan.o br_vlan_tunnel.o br_vlan_options.o

bridge-$(CONFIG_BRIDGE_VLAN_FILTERING) += br_vlan.o br_vlan_tunnel.o br_vlan_options.o br_mst.o



bridge-$(CONFIG_NET_SWITCHDEV) += br_switchdev.o

net/bridge/br.c

+5 −0
Original line number Diff line number Diff line
@@ -265,6 +265,9 @@ int br_boolopt_toggle(struct net_bridge *br, enum br_boolopt_id opt, bool on, 
	case BR_BOOLOPT_MCAST_VLAN_SNOOPING:

		err = br_multicast_toggle_vlan_snooping(br, on, extack);

		break;

	case BR_BOOLOPT_MST_ENABLE:

		err = br_mst_set_enabled(br, on, extack);

		break;

	default:

		/* shouldn't be called with unsupported options */

		WARN_ON(1);
@@ -281,6 +284,8 @@ int br_boolopt_get(const struct net_bridge *br, enum br_boolopt_id opt) 
		return br_opt_get(br, BROPT_NO_LL_LEARN);

	case BR_BOOLOPT_MCAST_VLAN_SNOOPING:

		return br_opt_get(br, BROPT_MCAST_VLAN_SNOOPING_ENABLED);

	case BR_BOOLOPT_MST_ENABLE:

		return br_opt_get(br, BROPT_MST_ENABLED);

	default:

		/* shouldn't be called with unsupported options */

		WARN_ON(1);

net/bridge/br_input.c

+15 −2
Original line number Diff line number Diff line
@@ -78,13 +78,22 @@ int br_handle_frame_finish(struct net *net, struct sock *sk, struct sk_buff *skb 
	u16 vid = 0;

	u8 state;



	if (!p || p->state == BR_STATE_DISABLED)

	if (!p)

		goto drop;



	br = p->br;



	if (br_mst_is_enabled(br)) {

		state = BR_STATE_FORWARDING;

	} else {

		if (p->state == BR_STATE_DISABLED)

			goto drop;



		state = p->state;

	}



	brmctx = &p->br->multicast_ctx;

	pmctx = &p->multicast_ctx;

	state = p->state;

	if (!br_allowed_ingress(p->br, nbp_vlan_group_rcu(p), skb, &vid,

				&state, &vlan))

		goto out;
@@ -370,9 +379,13 @@ static rx_handler_result_t br_handle_frame(struct sk_buff **pskb) 
		return RX_HANDLER_PASS;



forward:

	if (br_mst_is_enabled(p->br))

		goto defer_stp_filtering;



	switch (p->state) {

	case BR_STATE_FORWARDING:

	case BR_STATE_LEARNING:

defer_stp_filtering:

		if (ether_addr_equal(p->br->dev->dev_addr, dest))

			skb->pkt_type = PACKET_HOST;

net/bridge/br_mst.c

0 → 100644
+87 −0
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0-or-later

/*

 *	Bridge Multiple Spanning Tree Support

 *

 *	Authors:

 *	Tobias Waldekranz		<tobias@waldekranz.com>

 */



#include <linux/kernel.h>



#include "br_private.h"



DEFINE_STATIC_KEY_FALSE(br_mst_used);



static void br_mst_vlan_set_state(struct net_bridge_port *p, struct net_bridge_vlan *v,

				  u8 state)

{

	struct net_bridge_vlan_group *vg = nbp_vlan_group(p);



	if (v->state == state)

		return;



	br_vlan_set_state(v, state);



	if (v->vid == vg->pvid)

		br_vlan_set_pvid_state(vg, state);

}



int br_mst_set_state(struct net_bridge_port *p, u16 msti, u8 state,

		     struct netlink_ext_ack *extack)

{

	struct net_bridge_vlan_group *vg;

	struct net_bridge_vlan *v;



	vg = nbp_vlan_group(p);

	if (!vg)

		return 0;



	list_for_each_entry(v, &vg->vlan_list, vlist) {

		if (v->brvlan->msti != msti)

			continue;



		br_mst_vlan_set_state(p, v, state);

	}



	return 0;

}



void br_mst_vlan_init_state(struct net_bridge_vlan *v)

{

	/* VLANs always start out in MSTI 0 (CST) */

	v->msti = 0;



	if (br_vlan_is_master(v))

		v->state = BR_STATE_FORWARDING;

	else

		v->state = v->port->state;

}



int br_mst_set_enabled(struct net_bridge *br, bool on,

		       struct netlink_ext_ack *extack)

{

	struct net_bridge_vlan_group *vg;

	struct net_bridge_port *p;



	list_for_each_entry(p, &br->port_list, list) {

		vg = nbp_vlan_group(p);



		if (!vg->num_vlans)

			continue;



		NL_SET_ERR_MSG(extack,

			       "MST mode can't be changed while VLANs exist");

		return -EBUSY;

	}



	if (br_opt_get(br, BROPT_MST_ENABLED) == on)

		return 0;



	if (on)

		static_branch_enable(&br_mst_used);

	else

		static_branch_disable(&br_mst_used);



	br_opt_toggle(br, BROPT_MST_ENABLED, on);

	return 0;

}