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: Tobias Waldekranz <tobias@waldekranz.com>
Acked-by: Nikolay Aleksandrov <razor@blackwall.org>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/include/uapi/linux/if_bridge.h b/include/uapi/linux/if_bridge.h
index 2711c35..30a2421 100644 (file)
--- a/include/uapi/linux/if_bridge.h
+++ b/include/uapi/linux/if_bridge.h
@@ -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
 };
 

diff --git a/net/bridge/Makefile b/net/bridge/Makefile
index 7fb9a02..24bd1c0 100644 (file)
--- a/net/bridge/Makefile
+++ b/net/bridge/Makefile
@@ -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
 

diff --git a/net/bridge/br.c b/net/bridge/br.c
index b1dea3f..96e91d6 100644 (file)
--- a/net/bridge/br.c
+++ b/net/bridge/br.c
@@ -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);

diff --git a/net/bridge/br_input.c b/net/bridge/br_input.c
index e0c13fc..1964178 100644 (file)
--- a/net/bridge/br_input.c
+++ b/net/bridge/br_input.c
@@ -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;
 

diff --git a/net/bridge/br_mst.c b/net/bridge/br_mst.c
new file mode 100644 (file)
index 0000000..0f9f596
--- /dev/null
+++ b/net/bridge/br_mst.c
@@ -0,0 +1,87 @@
+// 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;
+}

diff --git a/net/bridge/br_private.h b/net/bridge/br_private.h
index 48bc61e..c2190c8 100644 (file)
--- a/net/bridge/br_private.h
+++ b/net/bridge/br_private.h
@@ -178,6 +178,7 @@ enum {
  * @br_mcast_ctx: if MASTER flag set, this is the global vlan multicast context
  * @port_mcast_ctx: if MASTER flag unset, this is the per-port/vlan multicast
  *                  context
+ * @msti: if MASTER flag set, this holds the VLANs MST instance
  * @vlist: sorted list of VLAN entries
  * @rcu: used for entry destruction
  *
@@ -210,6 +211,8 @@ struct net_bridge_vlan {
                struct net_bridge_mcast_port    port_mcast_ctx;
        };
 
+       u16                             msti;
+
        struct list_head                vlist;
 
        struct rcu_head                 rcu;
@@ -445,6 +448,7 @@ enum net_bridge_opts {
        BROPT_NO_LL_LEARN,
        BROPT_VLAN_BRIDGE_BINDING,
        BROPT_MCAST_VLAN_SNOOPING_ENABLED,
+       BROPT_MST_ENABLED,
 };
 
 struct net_bridge {
@@ -1765,6 +1769,39 @@ static inline bool br_vlan_state_allowed(u8 state, bool learn_allow)
 }
 #endif
 
+/* br_mst.c */
+#ifdef CONFIG_BRIDGE_VLAN_FILTERING
+DECLARE_STATIC_KEY_FALSE(br_mst_used);
+static inline bool br_mst_is_enabled(struct net_bridge *br)
+{
+       return static_branch_unlikely(&br_mst_used) &&
+               br_opt_get(br, BROPT_MST_ENABLED);
+}
+
+int br_mst_set_state(struct net_bridge_port *p, u16 msti, u8 state,
+                    struct netlink_ext_ack *extack);
+void br_mst_vlan_init_state(struct net_bridge_vlan *v);
+int br_mst_set_enabled(struct net_bridge *br, bool on,
+                      struct netlink_ext_ack *extack);
+#else
+static inline bool br_mst_is_enabled(struct net_bridge *br)
+{
+       return false;
+}
+
+static inline int br_mst_set_state(struct net_bridge_port *p, u16 msti,
+                                  u8 state, struct netlink_ext_ack *extack)
+{
+       return -EOPNOTSUPP;
+}
+
+static inline int br_mst_set_enabled(struct net_bridge *br, bool on,
+                                    struct netlink_ext_ack *extack)
+{
+       return -EOPNOTSUPP;
+}
+#endif
+
 struct nf_br_ops {
        int (*br_dev_xmit_hook)(struct sk_buff *skb);
 };

diff --git a/net/bridge/br_stp.c b/net/bridge/br_stp.c
index 1d80f34..7d27b2e 100644 (file)
--- a/net/bridge/br_stp.c
+++ b/net/bridge/br_stp.c
@@ -43,6 +43,12 @@ void br_set_state(struct net_bridge_port *p, unsigned int state)
                return;
 
        p->state = state;
+       if (br_opt_get(p->br, BROPT_MST_ENABLED)) {
+               err = br_mst_set_state(p, 0, state, NULL);
+               if (err)
+                       br_warn(p->br, "error setting MST state on port %u(%s)\n",
+                               p->port_no, netdev_name(p->dev));
+       }
        err = switchdev_port_attr_set(p->dev, &attr, NULL);
        if (err && err != -EOPNOTSUPP)
                br_warn(p->br, "error setting offload STP state on port %u(%s)\n",

diff --git a/net/bridge/br_vlan.c b/net/bridge/br_vlan.c
index 7557e90..0f5e75c 100644 (file)
--- a/net/bridge/br_vlan.c
+++ b/net/bridge/br_vlan.c
@@ -226,6 +226,24 @@ static void nbp_vlan_rcu_free(struct rcu_head *rcu)
        kfree(v);
 }
 
+static void br_vlan_init_state(struct net_bridge_vlan *v)
+{
+       struct net_bridge *br;
+
+       if (br_vlan_is_master(v))
+               br = v->br;
+       else
+               br = v->port->br;
+
+       if (br_opt_get(br, BROPT_MST_ENABLED)) {
+               br_mst_vlan_init_state(v);
+               return;
+       }
+
+       v->state = BR_STATE_FORWARDING;
+       v->msti = 0;
+}
+
 /* This is the shared VLAN add function which works for both ports and bridge
  * devices. There are four possible calls to this function in terms of the
  * vlan entry type:
@@ -322,7 +340,7 @@ static int __vlan_add(struct net_bridge_vlan *v, u16 flags,
        }
 
        /* set the state before publishing */
-       v->state = BR_STATE_FORWARDING;
+       br_vlan_init_state(v);
 
        err = rhashtable_lookup_insert_fast(&vg->vlan_hash, &v->vnode,
                                            br_vlan_rht_params);

diff --git a/net/bridge/br_vlan_options.c b/net/bridge/br_vlan_options.c
index a638297..09112b5 100644 (file)
--- a/net/bridge/br_vlan_options.c
+++ b/net/bridge/br_vlan_options.c
@@ -99,6 +99,11 @@ static int br_vlan_modify_state(struct net_bridge_vlan_group *vg,
                return -EBUSY;
        }
 
+       if (br_opt_get(br, BROPT_MST_ENABLED)) {
+               NL_SET_ERR_MSG_MOD(extack, "Can't modify vlan state directly when MST is enabled");
+               return -EBUSY;
+       }
+
        if (v->state == state)
                return 0;