Merge branch 'dsa-rx-filtering'

Vladimir Oltean says:

====================
RX filtering in DSA

This is my fourth stab (identical to the third one except sent as
non-RFC) at creating a list of unicast and multicast addresses that the
DSA CPU ports must trap. I am reusing a lot of Tobias's work which he
submitted here:
https://patchwork.kernel.org/project/netdevbpf/cover/[email protected]/

My additions to Tobias' work come in the form of taking some care that
additions and removals of host addresses are properly balanced, so that
we can do reference counting on them for cross-chip setups and multiple
bridges spanning the same switch (I am working on an NXP board where
both are real requirements).

During the last attempted submission of multiple CPU ports for DSA:
https://patchwork.kernel.org/project/netdevbpf/cover/[email protected]/

it became clear that the concept of multiple CPU ports would not be
compatible with the idea of address learning on those CPU ports (when
those CPU ports are statically assigned to user ports, not in a LAG)
unless the switch supports complete FDB isolation, which most switches
do not. So DSA needs to manage in software all addresses that are
installed on the CPU port(s), which is what this patch set does.

Compared to all earlier attempts, this series does not fiddle with how
DSA operates the ports in standalone mode at all, just when bridged.
We need to sort that out properly, then any optimization that comes in
standalone mode (i.e. IFF_UNICAST_FLT) can come later.
====================

Signed-off-by: David S. Miller <[email protected]>

Documentation/networking/dsa/configuration.rst

@@ -292,3 +292,71 @@ configuration.
 
     # bring up the bridge devices
     ip link set br0 up
+
+Forwarding database (FDB) management
+------------------------------------
+
+The existing DSA switches do not have the necessary hardware support to keep
+the software FDB of the bridge in sync with the hardware tables, so the two
+tables are managed separately (``bridge fdb show`` queries both, and depending
+on whether the ``self`` or ``master`` flags are being used, a ``bridge fdb
+add`` or ``bridge fdb del`` command acts upon entries from one or both tables).
+
+Up until kernel v4.14, DSA only supported user space management of bridge FDB
+entries using the bridge bypass operations (which do not update the software
+FDB, just the hardware one) using the ``self`` flag (which is optional and can
+be omitted).
+
+  .. code-block:: sh
+
+    bridge fdb add dev swp0 00:01:02:03:04:05 self static
+    # or shorthand
+    bridge fdb add dev swp0 00:01:02:03:04:05 static
+
+Due to a bug, the bridge bypass FDB implementation provided by DSA did not
+distinguish between ``static`` and ``local`` FDB entries (``static`` are meant
+to be forwarded, while ``local`` are meant to be locally terminated, i.e. sent
+to the host port). Instead, all FDB entries with the ``self`` flag (implicit or
+explicit) are treated by DSA as ``static`` even if they are ``local``.
+
+  .. code-block:: sh
+
+    # This command:
+    bridge fdb add dev swp0 00:01:02:03:04:05 static
+    # behaves the same for DSA as this command:
+    bridge fdb add dev swp0 00:01:02:03:04:05 local
+    # or shorthand, because the 'local' flag is implicit if 'static' is not
+    # specified, it also behaves the same as:
+    bridge fdb add dev swp0 00:01:02:03:04:05
+
+The last command is an incorrect way of adding a static bridge FDB entry to a
+DSA switch using the bridge bypass operations, and works by mistake. Other
+drivers will treat an FDB entry added by the same command as ``local`` and as
+such, will not forward it, as opposed to DSA.
+
+Between kernel v4.14 and v5.14, DSA has supported in parallel two modes of
+adding a bridge FDB entry to the switch: the bridge bypass discussed above, as
+well as a new mode using the ``master`` flag which installs FDB entries in the
+software bridge too.
+
+  .. code-block:: sh
+
+    bridge fdb add dev swp0 00:01:02:03:04:05 master static
+
+Since kernel v5.14, DSA has gained stronger integration with the bridge's
+software FDB, and the support for its bridge bypass FDB implementation (using
+the ``self`` flag) has been removed. This results in the following changes:
+
+  .. code-block:: sh
+
+    # This is the only valid way of adding an FDB entry that is supported,
+    # compatible with v4.14 kernels and later:
+    bridge fdb add dev swp0 00:01:02:03:04:05 master static
+    # This command is no longer buggy and the entry is properly treated as
+    # 'local' instead of being forwarded:
+    bridge fdb add dev swp0 00:01:02:03:04:05
+    # This command no longer installs a static FDB entry to hardware:
+    bridge fdb add dev swp0 00:01:02:03:04:05 static
+
+Script writers are therefore encouraged to use the ``master static`` set of
+flags when working with bridge FDB entries on DSA switch interfaces.

include/net/dsa.h

@@ -285,6 +285,12 @@ struct dsa_port {
 	 */
 	const struct dsa_netdevice_ops *netdev_ops;
 
+	/* List of MAC addresses that must be forwarded on this port.
+	 * These are only valid on CPU ports and DSA links.
+	 */
+	struct list_head	fdbs;
+	struct list_head	mdbs;
+
 	bool setup;
 };
 
@@ -299,6 +305,13 @@ struct dsa_link {
 	struct list_head list;
 };
 
+struct dsa_mac_addr {
+	unsigned char addr[ETH_ALEN];
+	u16 vid;
+	refcount_t refcount;
+	struct list_head list;
+};
+
 struct dsa_switch {
 	bool setup;
 
@@ -491,6 +504,32 @@ static inline unsigned int dsa_upstream_port(struct dsa_switch *ds, int port)
 	return dsa_towards_port(ds, cpu_dp->ds->index, cpu_dp->index);
 }
 
+/* Return true if this is the local port used to reach the CPU port */
+static inline bool dsa_is_upstream_port(struct dsa_switch *ds, int port)
+{
+	if (dsa_is_unused_port(ds, port))
+		return false;
+
+	return port == dsa_upstream_port(ds, port);
+}
+
+/* Return true if @upstream_ds is an upstream switch of @downstream_ds, meaning
+ * that the routing port from @downstream_ds to @upstream_ds is also the port
+ * which @downstream_ds uses to reach its dedicated CPU.
+ */
+static inline bool dsa_switch_is_upstream_of(struct dsa_switch *upstream_ds,
+					     struct dsa_switch *downstream_ds)
+{
+	int routing_port;
+
+	if (upstream_ds == downstream_ds)
+		return true;
+
+	routing_port = dsa_routing_port(downstream_ds, upstream_ds->index);
+
+	return dsa_is_upstream_port(downstream_ds, routing_port);
+}
+
 static inline bool dsa_port_is_vlan_filtering(const struct dsa_port *dp)
 {
 	const struct dsa_switch *ds = dp->ds;

net/bridge/br_fdb.c

@@ -440,9 +440,14 @@ int br_fdb_test_addr(struct net_device *dev, unsigned char *addr)
 	if (!port)
 		ret = 0;
 	else {
+		const struct net_bridge_port *dst = NULL;
+
 		fdb = br_fdb_find_rcu(port->br, addr, 0);
-		ret = fdb && fdb->dst && fdb->dst->dev != dev &&
-			fdb->dst->state == BR_STATE_FORWARDING;
+		if (fdb)
+			dst = READ_ONCE(fdb->dst);
+
+		ret = dst && dst->dev != dev &&
+		      dst->state == BR_STATE_FORWARDING;
 	}
 	rcu_read_unlock();
 
@@ -509,7 +514,7 @@ static struct net_bridge_fdb_entry *fdb_create(struct net_bridge *br,
 	fdb = kmem_cache_alloc(br_fdb_cache, GFP_ATOMIC);
 	if (fdb) {
 		memcpy(fdb->key.addr.addr, addr, ETH_ALEN);
-		fdb->dst = source;
+		WRITE_ONCE(fdb->dst, source);
 		fdb->key.vlan_id = vid;
 		fdb->flags = flags;
 		fdb->updated = fdb->used = jiffies;
@@ -600,10 +605,10 @@ void br_fdb_update(struct net_bridge *br, struct net_bridge_port *source,
 			}
 
 			/* fastpath: update of existing entry */
-			if (unlikely(source != fdb->dst &&
+			if (unlikely(source != READ_ONCE(fdb->dst) &&
 				     !test_bit(BR_FDB_STICKY, &fdb->flags))) {
-				br_switchdev_fdb_notify(fdb, RTM_DELNEIGH);
-				fdb->dst = source;
+				br_switchdev_fdb_notify(br, fdb, RTM_DELNEIGH);
+				WRITE_ONCE(fdb->dst, source);
 				fdb_modified = true;
 				/* Take over HW learned entry */
 				if (unlikely(test_bit(BR_FDB_ADDED_BY_EXT_LEARN,
@@ -650,6 +655,7 @@ static int fdb_fill_info(struct sk_buff *skb, const struct net_bridge *br,
 			 const struct net_bridge_fdb_entry *fdb,
 			 u32 portid, u32 seq, int type, unsigned int flags)
 {
+	const struct net_bridge_port *dst = READ_ONCE(fdb->dst);
 	unsigned long now = jiffies;
 	struct nda_cacheinfo ci;
 	struct nlmsghdr *nlh;
@@ -665,7 +671,7 @@ static int fdb_fill_info(struct sk_buff *skb, const struct net_bridge *br,
 	ndm->ndm_pad2    = 0;
 	ndm->ndm_flags	 = 0;
 	ndm->ndm_type	 = 0;
-	ndm->ndm_ifindex = fdb->dst ? fdb->dst->dev->ifindex : br->dev->ifindex;
+	ndm->ndm_ifindex = dst ? dst->dev->ifindex : br->dev->ifindex;
 	ndm->ndm_state   = fdb_to_nud(br, fdb);
 
 	if (test_bit(BR_FDB_OFFLOADED, &fdb->flags))
@@ -754,7 +760,10 @@ int br_fdb_replay(const struct net_device *br_dev, const struct net_device *dev,
 	unsigned long action;
 	int err = 0;
 
-	if (!netif_is_bridge_master(br_dev) || !netif_is_bridge_port(dev))
+	if (!netif_is_bridge_master(br_dev))
+		return -EINVAL;
+
+	if (!netif_is_bridge_port(dev) && !netif_is_bridge_master(dev))
 		return -EINVAL;
 
 	br = netdev_priv(br_dev);
@@ -794,7 +803,7 @@ static void fdb_notify(struct net_bridge *br,
 	int err = -ENOBUFS;
 
 	if (swdev_notify)
-		br_switchdev_fdb_notify(fdb, type);
+		br_switchdev_fdb_notify(br, fdb, type);
 
 	skb = nlmsg_new(fdb_nlmsg_size(), GFP_ATOMIC);
 	if (skb == NULL)
@@ -964,8 +973,8 @@ static int fdb_add_entry(struct net_bridge *br, struct net_bridge_port *source,
 		if (flags & NLM_F_EXCL)
 			return -EEXIST;
 
-		if (fdb->dst != source) {
-			fdb->dst = source;
+		if (READ_ONCE(fdb->dst) != source) {
+			WRITE_ONCE(fdb->dst, source);
 			modified = true;
 		}
 	}
@@ -1132,7 +1141,7 @@ static int fdb_delete_by_addr_and_port(struct net_bridge *br,
 	struct net_bridge_fdb_entry *fdb;
 
 	fdb = br_fdb_find(br, addr, vlan);
-	if (!fdb || fdb->dst != p)
+	if (!fdb || READ_ONCE(fdb->dst) != p)
 		return -ENOENT;
 
 	fdb_delete(br, fdb, true);
@@ -1281,8 +1290,8 @@ int br_fdb_external_learn_add(struct net_bridge *br, struct net_bridge_port *p,
 	} else {
 		fdb->updated = jiffies;
 
-		if (fdb->dst != p) {
-			fdb->dst = p;
+		if (READ_ONCE(fdb->dst) != p) {
+			WRITE_ONCE(fdb->dst, p);
 			modified = true;
 		}
 

net/bridge/br_private.h

@@ -1654,8 +1654,8 @@ int br_switchdev_set_port_flag(struct net_bridge_port *p,
 			       unsigned long flags,
 			       unsigned long mask,
 			       struct netlink_ext_ack *extack);
-void br_switchdev_fdb_notify(const struct net_bridge_fdb_entry *fdb,
-			     int type);
+void br_switchdev_fdb_notify(struct net_bridge *br,
+			     const struct net_bridge_fdb_entry *fdb, int type);
 int br_switchdev_port_vlan_add(struct net_device *dev, u16 vid, u16 flags,
 			       struct netlink_ext_ack *extack);
 int br_switchdev_port_vlan_del(struct net_device *dev, u16 vid);
@@ -1702,7 +1702,8 @@ static inline int br_switchdev_port_vlan_del(struct net_device *dev, u16 vid)
 }
 
 static inline void
-br_switchdev_fdb_notify(const struct net_bridge_fdb_entry *fdb, int type)
+br_switchdev_fdb_notify(struct net_bridge *br,
+			const struct net_bridge_fdb_entry *fdb, int type)
 {
 }
 

net/bridge/br_switchdev.c

@@ -108,8 +108,11 @@ int br_switchdev_set_port_flag(struct net_bridge_port *p,
 }
 
 void
-br_switchdev_fdb_notify(const struct net_bridge_fdb_entry *fdb, int type)
+br_switchdev_fdb_notify(struct net_bridge *br,
+			const struct net_bridge_fdb_entry *fdb, int type)
 {
+	const struct net_bridge_port *dst = READ_ONCE(fdb->dst);
+	struct net_device *dev = dst ? dst->dev : br->dev;
 	struct switchdev_notifier_fdb_info info = {
 		.addr = fdb->key.addr.addr,
 		.vid = fdb->key.vlan_id,
@@ -118,17 +121,14 @@ br_switchdev_fdb_notify(const struct net_bridge_fdb_entry *fdb, int type)
 		.offloaded = test_bit(BR_FDB_OFFLOADED, &fdb->flags),
 	};
 
-	if (!fdb->dst)
-		return;
-
 	switch (type) {
 	case RTM_DELNEIGH:
 		call_switchdev_notifiers(SWITCHDEV_FDB_DEL_TO_DEVICE,
-					 fdb->dst->dev, &info.info, NULL);
+					 dev, &info.info, NULL);
 		break;
 	case RTM_NEWNEIGH:
 		call_switchdev_notifiers(SWITCHDEV_FDB_ADD_TO_DEVICE,
-					 fdb->dst->dev, &info.info, NULL);
+					 dev, &info.info, NULL);
 		break;
 	}
 }

net/dsa/dsa2.c

@@ -348,6 +348,9 @@ static int dsa_port_setup(struct dsa_port *dp)
 	if (dp->setup)
 		return 0;
 
+	INIT_LIST_HEAD(&dp->fdbs);
+	INIT_LIST_HEAD(&dp->mdbs);
+
 	switch (dp->type) {
 	case DSA_PORT_TYPE_UNUSED:
 		dsa_port_disable(dp);
@@ -443,6 +446,7 @@ static int dsa_port_devlink_setup(struct dsa_port *dp)
 static void dsa_port_teardown(struct dsa_port *dp)
 {
 	struct devlink_port *dlp = &dp->devlink_port;
+	struct dsa_mac_addr *a, *tmp;
 
 	if (!dp->setup)
 		return;
@@ -468,6 +472,16 @@ static void dsa_port_teardown(struct dsa_port *dp)
 		break;
 	}
 
+	list_for_each_entry_safe(a, tmp, &dp->fdbs, list) {
+		list_del(&a->list);
+		kfree(a);
+	}
+
+	list_for_each_entry_safe(a, tmp, &dp->mdbs, list) {
+		list_del(&a->list);
+		kfree(a);
+	}
+
 	dp->setup = false;
 }
 

net/dsa/dsa_priv.h

@@ -20,13 +20,17 @@ enum {
 	DSA_NOTIFIER_BRIDGE_LEAVE,
 	DSA_NOTIFIER_FDB_ADD,
 	DSA_NOTIFIER_FDB_DEL,
+	DSA_NOTIFIER_HOST_FDB_ADD,
+	DSA_NOTIFIER_HOST_FDB_DEL,
 	DSA_NOTIFIER_HSR_JOIN,
 	DSA_NOTIFIER_HSR_LEAVE,
 	DSA_NOTIFIER_LAG_CHANGE,
 	DSA_NOTIFIER_LAG_JOIN,
 	DSA_NOTIFIER_LAG_LEAVE,
 	DSA_NOTIFIER_MDB_ADD,
 	DSA_NOTIFIER_MDB_DEL,
+	DSA_NOTIFIER_HOST_MDB_ADD,
+	DSA_NOTIFIER_HOST_MDB_DEL,
 	DSA_NOTIFIER_VLAN_ADD,
 	DSA_NOTIFIER_VLAN_DEL,
 	DSA_NOTIFIER_MTU,
@@ -112,13 +116,15 @@ struct dsa_notifier_mrp_ring_role_info {
 struct dsa_switchdev_event_work {
 	struct dsa_switch *ds;
 	int port;
+	struct net_device *dev;
 	struct work_struct work;
 	unsigned long event;
 	/* Specific for SWITCHDEV_FDB_ADD_TO_DEVICE and
 	 * SWITCHDEV_FDB_DEL_TO_DEVICE
 	 */
 	unsigned char addr[ETH_ALEN];
 	u16 vid;
+	bool host_addr;
 };
 
 /* DSA_NOTIFIER_HSR_* */
@@ -209,11 +215,19 @@ int dsa_port_fdb_add(struct dsa_port *dp, const unsigned char *addr,
 		     u16 vid);
 int dsa_port_fdb_del(struct dsa_port *dp, const unsigned char *addr,
 		     u16 vid);
+int dsa_port_host_fdb_add(struct dsa_port *dp, const unsigned char *addr,
+			  u16 vid);
+int dsa_port_host_fdb_del(struct dsa_port *dp, const unsigned char *addr,
+			  u16 vid);
 int dsa_port_fdb_dump(struct dsa_port *dp, dsa_fdb_dump_cb_t *cb, void *data);
 int dsa_port_mdb_add(const struct dsa_port *dp,
 		     const struct switchdev_obj_port_mdb *mdb);
 int dsa_port_mdb_del(const struct dsa_port *dp,
 		     const struct switchdev_obj_port_mdb *mdb);
+int dsa_port_host_mdb_add(const struct dsa_port *dp,
+			  const struct switchdev_obj_port_mdb *mdb);
+int dsa_port_host_mdb_del(const struct dsa_port *dp,
+			  const struct switchdev_obj_port_mdb *mdb);
 int dsa_port_pre_bridge_flags(const struct dsa_port *dp,
 			      struct switchdev_brport_flags flags,
 			      struct netlink_ext_ack *extack);