kernel: add a bridge feature for filtering BPDU packets on ports

This will be used to ensure that APs don't transmit unnecessary STP packets

Signed-off-by: Felix Fietkau <nbd@nbd.name>

2 files changed, 354 insertions, 0 deletions

diff --git a/target/linux/generic/pending-5.10/710-bridge-add-knob-for-filtering-rx-tx-BPDU-pack.patch b/target/linux/generic/pending-5.10/710-bridge-add-knob-for-filtering-rx-tx-BPDU-pack.patch
new file mode 100644
index 0000000000..f05ff3bc04
--- /dev/null
+++ b/target/linux/generic/pending-5.10/710-bridge-add-knob-for-filtering-rx-tx-BPDU-pack.patch
@@ -0,0 +1,177 @@
+From: Felix Fietkau <nbd@nbd.name>
+Date: Fri, 27 Aug 2021 12:22:32 +0200
+Subject: [PATCH] bridge: add knob for filtering rx/tx BPDU packets on a port
+
+Some devices (e.g. wireless APs) can't have devices behind them be part of
+a bridge topology with redundant links, due to address limitations.
+Additionally, broadcast traffic on these devices is somewhat expensive, due to
+the low data rate and wakeups of clients in powersave mode.
+This knob can be used to ensure that BPDU packets are never sent or forwarded
+to/from these devices
+
+Signed-off-by: Felix Fietkau <nbd@nbd.name>
+---
+
+--- a/include/linux/if_bridge.h
++++ b/include/linux/if_bridge.h
+@@ -56,6 +56,7 @@ struct br_ip_list {
+ #define BR_MRP_AWARE		BIT(17)
+ #define BR_MRP_LOST_CONT	BIT(18)
+ #define BR_MRP_LOST_IN_CONT	BIT(19)
++#define BR_BPDU_FILTER		BIT(20)
+ 
+ #define BR_DEFAULT_AGEING_TIME	(300 * HZ)
+ 
+--- a/net/bridge/br_forward.c
++++ b/net/bridge/br_forward.c
+@@ -191,6 +191,7 @@ out:
+ void br_flood(struct net_bridge *br, struct sk_buff *skb,
+ 	      enum br_pkt_type pkt_type, bool local_rcv, bool local_orig)
+ {
++	const unsigned char *dest = eth_hdr(skb)->h_dest;
+ 	struct net_bridge_port *prev = NULL;
+ 	struct net_bridge_port *p;
+ 
+@@ -206,6 +207,10 @@ void br_flood(struct net_bridge *br, str
+ 		case BR_PKT_MULTICAST:
+ 			if (!(p->flags & BR_MCAST_FLOOD) && skb->dev != br->dev)
+ 				continue;
++			if ((p->flags & BR_BPDU_FILTER) &&
++			    unlikely(is_link_local_ether_addr(dest) &&
++				     dest[5] == 0))
++				continue;
+ 			break;
+ 		case BR_PKT_BROADCAST:
+ 			if (!(p->flags & BR_BCAST_FLOOD) && skb->dev != br->dev)
+--- a/net/bridge/br_input.c
++++ b/net/bridge/br_input.c
+@@ -305,6 +305,8 @@ static rx_handler_result_t br_handle_fra
+ 		fwd_mask |= p->group_fwd_mask;
+ 		switch (dest[5]) {
+ 		case 0x00:	/* Bridge Group Address */
++			if (p->flags & BR_BPDU_FILTER)
++				goto drop;
+ 			/* If STP is turned off,
+ 			   then must forward to keep loop detection */
+ 			if (p->br->stp_enabled == BR_NO_STP ||
+--- a/net/bridge/br_sysfs_if.c
++++ b/net/bridge/br_sysfs_if.c
+@@ -233,6 +233,7 @@ BRPORT_ATTR_FLAG(multicast_flood, BR_MCA
+ BRPORT_ATTR_FLAG(broadcast_flood, BR_BCAST_FLOOD);
+ BRPORT_ATTR_FLAG(neigh_suppress, BR_NEIGH_SUPPRESS);
+ BRPORT_ATTR_FLAG(isolated, BR_ISOLATED);
++BRPORT_ATTR_FLAG(bpdu_filter, BR_BPDU_FILTER);
+ 
+ #ifdef CONFIG_BRIDGE_IGMP_SNOOPING
+ static ssize_t show_multicast_router(struct net_bridge_port *p, char *buf)
+@@ -285,6 +286,7 @@ static const struct brport_attribute *br
+ 	&brport_attr_group_fwd_mask,
+ 	&brport_attr_neigh_suppress,
+ 	&brport_attr_isolated,
++	&brport_attr_bpdu_filter,
+ 	&brport_attr_backup_port,
+ 	NULL
+ };
+--- a/net/bridge/br_stp_bpdu.c
++++ b/net/bridge/br_stp_bpdu.c
+@@ -80,7 +80,8 @@ void br_send_config_bpdu(struct net_brid
+ {
+ 	unsigned char buf[35];
+ 
+-	if (p->br->stp_enabled != BR_KERNEL_STP)
++	if (p->br->stp_enabled != BR_KERNEL_STP ||
++	    (p->flags & BR_BPDU_FILTER))
+ 		return;
+ 
+ 	buf[0] = 0;
+@@ -127,7 +128,8 @@ void br_send_tcn_bpdu(struct net_bridge_
+ {
+ 	unsigned char buf[4];
+ 
+-	if (p->br->stp_enabled != BR_KERNEL_STP)
++	if (p->br->stp_enabled != BR_KERNEL_STP ||
++	    (p->flags & BR_BPDU_FILTER))
+ 		return;
+ 
+ 	buf[0] = 0;
+@@ -172,6 +174,9 @@ void br_stp_rcv(const struct stp_proto *
+ 	if (!(br->dev->flags & IFF_UP))
+ 		goto out;
+ 
++	if (p->flags & BR_BPDU_FILTER)
++		goto out;
++
+ 	if (p->state == BR_STATE_DISABLED)
+ 		goto out;
+ 
+--- a/include/uapi/linux/if_link.h
++++ b/include/uapi/linux/if_link.h
+@@ -524,6 +524,7 @@ enum {
+ 	IFLA_BRPORT_BACKUP_PORT,
+ 	IFLA_BRPORT_MRP_RING_OPEN,
+ 	IFLA_BRPORT_MRP_IN_OPEN,
++	IFLA_BRPORT_BPDU_FILTER,
+ 	__IFLA_BRPORT_MAX
+ };
+ #define IFLA_BRPORT_MAX (__IFLA_BRPORT_MAX - 1)
+--- a/net/bridge/br_netlink.c
++++ b/net/bridge/br_netlink.c
+@@ -137,6 +137,7 @@ static inline size_t br_port_info_size(v
+ 		+ nla_total_size(1)	/* IFLA_BRPORT_VLAN_TUNNEL */
+ 		+ nla_total_size(1)	/* IFLA_BRPORT_NEIGH_SUPPRESS */
+ 		+ nla_total_size(1)	/* IFLA_BRPORT_ISOLATED */
++		+ nla_total_size(1)	/* IFLA_BRPORT_BPDU_FILTER */
+ 		+ nla_total_size(sizeof(struct ifla_bridge_id))	/* IFLA_BRPORT_ROOT_ID */
+ 		+ nla_total_size(sizeof(struct ifla_bridge_id))	/* IFLA_BRPORT_BRIDGE_ID */
+ 		+ nla_total_size(sizeof(u16))	/* IFLA_BRPORT_DESIGNATED_PORT */
+@@ -220,7 +221,8 @@ static int br_port_fill_attrs(struct sk_
+ 							  BR_MRP_LOST_CONT)) ||
+ 	    nla_put_u8(skb, IFLA_BRPORT_MRP_IN_OPEN,
+ 		       !!(p->flags & BR_MRP_LOST_IN_CONT)) ||
+-	    nla_put_u8(skb, IFLA_BRPORT_ISOLATED, !!(p->flags & BR_ISOLATED)))
++	    nla_put_u8(skb, IFLA_BRPORT_ISOLATED, !!(p->flags & BR_ISOLATED)) ||
++	    nla_put_u8(skb, IFLA_BRPORT_BPDU_FILTER, !!(p->flags & BR_BPDU_FILTER)))
+ 		return -EMSGSIZE;
+ 
+ 	timerval = br_timer_value(&p->message_age_timer);
+@@ -728,6 +730,7 @@ static const struct nla_policy br_port_p
+ 	[IFLA_BRPORT_NEIGH_SUPPRESS] = { .type = NLA_U8 },
+ 	[IFLA_BRPORT_ISOLATED]	= { .type = NLA_U8 },
+ 	[IFLA_BRPORT_BACKUP_PORT] = { .type = NLA_U32 },
++	[IFLA_BRPORT_BPDU_FILTER] = { .type = NLA_U8 },
+ };
+ 
+ /* Change the state of the port and notify spanning tree */
+@@ -826,6 +829,10 @@ static int br_setport(struct net_bridge_
+ 	if (err)
+ 		return err;
+ 
++	err = br_set_port_flag(p, tb, IFLA_BRPORT_BPDU_FILTER, BR_BPDU_FILTER);
++	if (err)
++		return err;
++
+ 	br_vlan_tunnel_old = (p->flags & BR_VLAN_TUNNEL) ? true : false;
+ 	err = br_set_port_flag(p, tb, IFLA_BRPORT_VLAN_TUNNEL, BR_VLAN_TUNNEL);
+ 	if (err)
+--- a/net/core/rtnetlink.c
++++ b/net/core/rtnetlink.c
+@@ -55,7 +55,7 @@
+ #include <net/net_namespace.h>
+ 
+ #define RTNL_MAX_TYPE		50
+-#define RTNL_SLAVE_MAX_TYPE	36
++#define RTNL_SLAVE_MAX_TYPE	37
+ 
+ struct rtnl_link {
+ 	rtnl_doit_func		doit;
+@@ -4680,7 +4680,9 @@ int ndo_dflt_bridge_getlink(struct sk_bu
+ 	    brport_nla_put_flag(skb, flags, mask,
+ 				IFLA_BRPORT_MCAST_FLOOD, BR_MCAST_FLOOD) ||
+ 	    brport_nla_put_flag(skb, flags, mask,
+-				IFLA_BRPORT_BCAST_FLOOD, BR_BCAST_FLOOD)) {
++				IFLA_BRPORT_BCAST_FLOOD, BR_BCAST_FLOOD) ||
++	    brport_nla_put_flag(skb, flags, mask,
++				IFLA_BRPORT_BPDU_FILTER, BR_BPDU_FILTER)) {
+ 		nla_nest_cancel(skb, protinfo);
+ 		goto nla_put_failure;
+ 	}
diff --git a/target/linux/generic/pending-5.4/710-bridge-add-knob-for-filtering-rx-tx-BPDU-pack.patch b/target/linux/generic/pending-5.4/710-bridge-add-knob-for-filtering-rx-tx-BPDU-pack.patch
new file mode 100644
index 0000000000..90e0d0de83
--- /dev/null
+++ b/target/linux/generic/pending-5.4/710-bridge-add-knob-for-filtering-rx-tx-BPDU-pack.patch
@@ -0,0 +1,177 @@
+From: Felix Fietkau <nbd@nbd.name>
+Date: Fri, 27 Aug 2021 12:22:32 +0200
+Subject: [PATCH] bridge: add knob for filtering rx/tx BPDU packets on a port
+
+Some devices (e.g. wireless APs) can't have devices behind them be part of
+a bridge topology with redundant links, due to address limitations.
+Additionally, broadcast traffic on these devices is somewhat expensive, due to
+the low data rate and wakeups of clients in powersave mode.
+This knob can be used to ensure that BPDU packets are never sentor forwarded
+to/from these devices
+
+Signed-off-by: Felix Fietkau <nbd@nbd.name>
+---
+
+--- a/include/linux/if_bridge.h
++++ b/include/linux/if_bridge.h
+@@ -47,6 +47,7 @@ struct br_ip_list {
+ #define BR_BCAST_FLOOD		BIT(14)
+ #define BR_NEIGH_SUPPRESS	BIT(15)
+ #define BR_ISOLATED		BIT(16)
++#define BR_BPDU_FILTER		BIT(17)
+ 
+ #define BR_DEFAULT_AGEING_TIME	(300 * HZ)
+ 
+--- a/net/bridge/br_forward.c
++++ b/net/bridge/br_forward.c
+@@ -191,6 +191,7 @@ out:
+ void br_flood(struct net_bridge *br, struct sk_buff *skb,
+ 	      enum br_pkt_type pkt_type, bool local_rcv, bool local_orig)
+ {
++	const unsigned char *dest = eth_hdr(skb)->h_dest;
+ 	struct net_bridge_port *prev = NULL;
+ 	struct net_bridge_port *p;
+ 
+@@ -206,6 +207,10 @@ void br_flood(struct net_bridge *br, str
+ 		case BR_PKT_MULTICAST:
+ 			if (!(p->flags & BR_MCAST_FLOOD) && skb->dev != br->dev)
+ 				continue;
++			if ((p->flags & BR_BPDU_FILTER) &&
++			    unlikely(is_link_local_ether_addr(dest) &&
++				     dest[5] == 0))
++				continue;
+ 			break;
+ 		case BR_PKT_BROADCAST:
+ 			if (!(p->flags & BR_BCAST_FLOOD) && skb->dev != br->dev)
+--- a/net/bridge/br_input.c
++++ b/net/bridge/br_input.c
+@@ -300,6 +300,8 @@ rx_handler_result_t br_handle_frame(stru
+ 		fwd_mask |= p->group_fwd_mask;
+ 		switch (dest[5]) {
+ 		case 0x00:	/* Bridge Group Address */
++			if (p->flags & BR_BPDU_FILTER)
++				goto drop;
+ 			/* If STP is turned off,
+ 			   then must forward to keep loop detection */
+ 			if (p->br->stp_enabled == BR_NO_STP ||
+--- a/net/bridge/br_sysfs_if.c
++++ b/net/bridge/br_sysfs_if.c
+@@ -233,6 +233,7 @@ BRPORT_ATTR_FLAG(multicast_flood, BR_MCA
+ BRPORT_ATTR_FLAG(broadcast_flood, BR_BCAST_FLOOD);
+ BRPORT_ATTR_FLAG(neigh_suppress, BR_NEIGH_SUPPRESS);
+ BRPORT_ATTR_FLAG(isolated, BR_ISOLATED);
++BRPORT_ATTR_FLAG(bpdu_filter, BR_BPDU_FILTER);
+ 
+ #ifdef CONFIG_BRIDGE_IGMP_SNOOPING
+ static ssize_t show_multicast_router(struct net_bridge_port *p, char *buf)
+@@ -285,6 +286,7 @@ static const struct brport_attribute *br
+ 	&brport_attr_group_fwd_mask,
+ 	&brport_attr_neigh_suppress,
+ 	&brport_attr_isolated,
++	&brport_attr_bpdu_filter,
+ 	&brport_attr_backup_port,
+ 	NULL
+ };
+--- a/net/bridge/br_stp_bpdu.c
++++ b/net/bridge/br_stp_bpdu.c
+@@ -80,7 +80,8 @@ void br_send_config_bpdu(struct net_brid
+ {
+ 	unsigned char buf[35];
+ 
+-	if (p->br->stp_enabled != BR_KERNEL_STP)
++	if (p->br->stp_enabled != BR_KERNEL_STP ||
++	    (p->flags & BR_BPDU_FILTER))
+ 		return;
+ 
+ 	buf[0] = 0;
+@@ -125,7 +126,8 @@ void br_send_tcn_bpdu(struct net_bridge_
+ {
+ 	unsigned char buf[4];
+ 
+-	if (p->br->stp_enabled != BR_KERNEL_STP)
++	if (p->br->stp_enabled != BR_KERNEL_STP ||
++	    (p->flags & BR_BPDU_FILTER))
+ 		return;
+ 
+ 	buf[0] = 0;
+@@ -168,6 +170,9 @@ void br_stp_rcv(const struct stp_proto *
+ 	if (!(br->dev->flags & IFF_UP))
+ 		goto out;
+ 
++	if (p->flags & BR_BPDU_FILTER)
++		goto out;
++
+ 	if (p->state == BR_STATE_DISABLED)
+ 		goto out;
+ 
+--- a/include/uapi/linux/if_link.h
++++ b/include/uapi/linux/if_link.h
+@@ -340,6 +340,7 @@ enum {
+ 	IFLA_BRPORT_NEIGH_SUPPRESS,
+ 	IFLA_BRPORT_ISOLATED,
+ 	IFLA_BRPORT_BACKUP_PORT,
++	IFLA_BRPORT_BPDU_FILTER,
+ 	__IFLA_BRPORT_MAX
+ };
+ #define IFLA_BRPORT_MAX (__IFLA_BRPORT_MAX - 1)
+--- a/net/bridge/br_netlink.c
++++ b/net/bridge/br_netlink.c
+@@ -137,6 +137,7 @@ static inline size_t br_port_info_size(v
+ 		+ nla_total_size(1)	/* IFLA_BRPORT_VLAN_TUNNEL */
+ 		+ nla_total_size(1)	/* IFLA_BRPORT_NEIGH_SUPPRESS */
+ 		+ nla_total_size(1)	/* IFLA_BRPORT_ISOLATED */
++		+ nla_total_size(1)	/* IFLA_BRPORT_BPDU_FILTER */
+ 		+ nla_total_size(sizeof(struct ifla_bridge_id))	/* IFLA_BRPORT_ROOT_ID */
+ 		+ nla_total_size(sizeof(struct ifla_bridge_id))	/* IFLA_BRPORT_BRIDGE_ID */
+ 		+ nla_total_size(sizeof(u16))	/* IFLA_BRPORT_DESIGNATED_PORT */
+@@ -214,7 +215,8 @@ static int br_port_fill_attrs(struct sk_
+ 	    nla_put_u16(skb, IFLA_BRPORT_GROUP_FWD_MASK, p->group_fwd_mask) ||
+ 	    nla_put_u8(skb, IFLA_BRPORT_NEIGH_SUPPRESS,
+ 		       !!(p->flags & BR_NEIGH_SUPPRESS)) ||
+-	    nla_put_u8(skb, IFLA_BRPORT_ISOLATED, !!(p->flags & BR_ISOLATED)))
++	    nla_put_u8(skb, IFLA_BRPORT_ISOLATED, !!(p->flags & BR_ISOLATED)) ||
++	    nla_put_u8(skb, IFLA_BRPORT_BPDU_FILTER, !!(p->flags & BR_BPDU_FILTER)))
+ 		return -EMSGSIZE;
+ 
+ 	timerval = br_timer_value(&p->message_age_timer);
+@@ -676,6 +678,7 @@ static const struct nla_policy br_port_p
+ 	[IFLA_BRPORT_NEIGH_SUPPRESS] = { .type = NLA_U8 },
+ 	[IFLA_BRPORT_ISOLATED]	= { .type = NLA_U8 },
+ 	[IFLA_BRPORT_BACKUP_PORT] = { .type = NLA_U32 },
++	[IFLA_BRPORT_BPDU_FILTER] = { .type = NLA_U8 },
+ };
+ 
+ /* Change the state of the port and notify spanning tree */
+@@ -774,6 +777,10 @@ static int br_setport(struct net_bridge_
+ 	if (err)
+ 		return err;
+ 
++	err = br_set_port_flag(p, tb, IFLA_BRPORT_BPDU_FILTER, BR_BPDU_FILTER);
++	if (err)
++		return err;
++
+ 	br_vlan_tunnel_old = (p->flags & BR_VLAN_TUNNEL) ? true : false;
+ 	err = br_set_port_flag(p, tb, IFLA_BRPORT_VLAN_TUNNEL, BR_VLAN_TUNNEL);
+ 	if (err)
+--- a/net/core/rtnetlink.c
++++ b/net/core/rtnetlink.c
+@@ -55,7 +55,7 @@
+ #include <net/net_namespace.h>
+ 
+ #define RTNL_MAX_TYPE		50
+-#define RTNL_SLAVE_MAX_TYPE	36
++#define RTNL_SLAVE_MAX_TYPE	37
+ 
+ struct rtnl_link {
+ 	rtnl_doit_func		doit;
+@@ -4373,7 +4373,9 @@ int ndo_dflt_bridge_getlink(struct sk_bu
+ 	    brport_nla_put_flag(skb, flags, mask,
+ 				IFLA_BRPORT_UNICAST_FLOOD, BR_FLOOD) ||
+ 	    brport_nla_put_flag(skb, flags, mask,
+-				IFLA_BRPORT_PROXYARP, BR_PROXYARP)) {
++				IFLA_BRPORT_PROXYARP, BR_PROXYARP) ||
++	    brport_nla_put_flag(skb, flags, mask,
++				IFLA_BRPORT_BPDU_FILTER, BR_BPDU_FILTER)) {
+ 		nla_nest_cancel(skb, protinfo);
+ 		goto nla_put_failure;
+ 	}