net: bridge: mst: Support setting and reporting MST port states

Make it possible to change the port state in a given MSTI by extending
the bridge port netlink interface (RTM_SETLINK on PF_BRIDGE).The
proposed iproute2 interface would be:

    bridge mst set dev <PORT> msti <MSTI> state <STATE>

Current states in all applicable MSTIs can also be dumped via a
corresponding RTM_GETLINK. The proposed iproute interface looks like
this:

$ bridge mst
port              msti
vb1               0
		    state forwarding
		  100
		    state disabled
vb2               0
		    state forwarding
		  100
		    state forwarding

The preexisting per-VLAN states are still valid in the MST
mode (although they are read-only), and can be queried as usual if one
is interested in knowing a particular VLAN's state without having to
care about the VID to MSTI mapping (in this example VLAN 20 and 30 are
bound to MSTI 100):

$ bridge -d vlan
port              vlan-id
vb1               10
		    state forwarding mcast_router 1
		  20
		    state disabled mcast_router 1
		  30
		    state disabled mcast_router 1
		  40
		    state forwarding mcast_router 1
vb2               10
		    state forwarding mcast_router 1
		  20
		    state forwarding mcast_router 1
		  30
		    state forwarding mcast_router 1
		  40
		    state forwarding mcast_router 1

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

3 files changed, 192 insertions, 1 deletions

diff --git a/net/bridge/br_mst.c b/net/bridge/br_mst.c
index d7a7b5d7ddb3..5c1831c73fc2 100644
--- a/net/bridge/br_mst.c
+++ b/net/bridge/br_mst.c
@@ -127,3 +127,129 @@ int br_mst_set_enabled(struct net_bridge *br, bool on,
 	br_opt_toggle(br, BROPT_MST_ENABLED, on);
 	return 0;
 }
+
+size_t br_mst_info_size(const struct net_bridge_vlan_group *vg)
+{
+	DECLARE_BITMAP(seen, VLAN_N_VID) = { 0 };
+	const struct net_bridge_vlan *v;
+	size_t sz;
+
+	/* IFLA_BRIDGE_MST */
+	sz = nla_total_size(0);
+
+	list_for_each_entry_rcu(v, &vg->vlan_list, vlist) {
+		if (test_bit(v->brvlan->msti, seen))
+			continue;
+
+		/* IFLA_BRIDGE_MST_ENTRY */
+		sz += nla_total_size(0) +
+			/* IFLA_BRIDGE_MST_ENTRY_MSTI */
+			nla_total_size(sizeof(u16)) +
+			/* IFLA_BRIDGE_MST_ENTRY_STATE */
+			nla_total_size(sizeof(u8));
+
+		__set_bit(v->brvlan->msti, seen);
+	}
+
+	return sz;
+}
+
+int br_mst_fill_info(struct sk_buff *skb,
+		     const struct net_bridge_vlan_group *vg)
+{
+	DECLARE_BITMAP(seen, VLAN_N_VID) = { 0 };
+	const struct net_bridge_vlan *v;
+	struct nlattr *nest;
+	int err = 0;
+
+	list_for_each_entry(v, &vg->vlan_list, vlist) {
+		if (test_bit(v->brvlan->msti, seen))
+			continue;
+
+		nest = nla_nest_start_noflag(skb, IFLA_BRIDGE_MST_ENTRY);
+		if (!nest ||
+		    nla_put_u16(skb, IFLA_BRIDGE_MST_ENTRY_MSTI, v->brvlan->msti) ||
+		    nla_put_u8(skb, IFLA_BRIDGE_MST_ENTRY_STATE, v->state)) {
+			err = -EMSGSIZE;
+			break;
+		}
+		nla_nest_end(skb, nest);
+
+		__set_bit(v->brvlan->msti, seen);
+	}
+
+	return err;
+}
+
+static const struct nla_policy br_mst_nl_policy[IFLA_BRIDGE_MST_ENTRY_MAX + 1] = {
+	[IFLA_BRIDGE_MST_ENTRY_MSTI] = NLA_POLICY_RANGE(NLA_U16,
+						   1, /* 0 reserved for CST */
+						   VLAN_N_VID - 1),
+	[IFLA_BRIDGE_MST_ENTRY_STATE] = NLA_POLICY_RANGE(NLA_U8,
+						    BR_STATE_DISABLED,
+						    BR_STATE_BLOCKING),
+};
+
+static int br_mst_process_one(struct net_bridge_port *p,
+			      const struct nlattr *attr,
+			      struct netlink_ext_ack *extack)
+{
+	struct nlattr *tb[IFLA_BRIDGE_MST_ENTRY_MAX + 1];
+	u16 msti;
+	u8 state;
+	int err;
+
+	err = nla_parse_nested(tb, IFLA_BRIDGE_MST_ENTRY_MAX, attr,
+			       br_mst_nl_policy, extack);
+	if (err)
+		return err;
+
+	if (!tb[IFLA_BRIDGE_MST_ENTRY_MSTI]) {
+		NL_SET_ERR_MSG_MOD(extack, "MSTI not specified");
+		return -EINVAL;
+	}
+
+	if (!tb[IFLA_BRIDGE_MST_ENTRY_STATE]) {
+		NL_SET_ERR_MSG_MOD(extack, "State not specified");
+		return -EINVAL;
+	}
+
+	msti = nla_get_u16(tb[IFLA_BRIDGE_MST_ENTRY_MSTI]);
+	state = nla_get_u8(tb[IFLA_BRIDGE_MST_ENTRY_STATE]);
+
+	return br_mst_set_state(p, msti, state, extack);
+}
+
+int br_mst_process(struct net_bridge_port *p, const struct nlattr *mst_attr,
+		   struct netlink_ext_ack *extack)
+{
+	struct nlattr *attr;
+	int err, msts = 0;
+	int rem;
+
+	if (!br_opt_get(p->br, BROPT_MST_ENABLED)) {
+		NL_SET_ERR_MSG_MOD(extack, "Can't modify MST state when MST is disabled");
+		return -EBUSY;
+	}
+
+	nla_for_each_nested(attr, mst_attr, rem) {
+		switch (nla_type(attr)) {
+		case IFLA_BRIDGE_MST_ENTRY:
+			err = br_mst_process_one(p, attr, extack);
+			break;
+		default:
+			continue;
+		}
+
+		msts++;
+		if (err)
+			break;
+	}
+
+	if (!msts) {
+		NL_SET_ERR_MSG_MOD(extack, "Found no MST entries to process");
+		err = -EINVAL;
+	}
+
+	return err;
+}
diff --git a/net/bridge/br_netlink.c b/net/bridge/br_netlink.c
index 7d4432ca9a20..a8d90fa8621e 100644
--- a/net/bridge/br_netlink.c
+++ b/net/bridge/br_netlink.c
@@ -119,6 +119,9 @@ static size_t br_get_link_af_size_filtered(const struct net_device *dev,
 	/* Each VLAN is returned in bridge_vlan_info along with flags */
 	vinfo_sz += num_vlan_infos * nla_total_size(sizeof(struct bridge_vlan_info));
 
+	if (filter_mask & RTEXT_FILTER_MST)
+		vinfo_sz += br_mst_info_size(vg);
+
 	if (!(filter_mask & RTEXT_FILTER_CFM_STATUS))
 		return vinfo_sz;
 
@@ -485,7 +488,8 @@ static int br_fill_ifinfo(struct sk_buff *skb,
 			   RTEXT_FILTER_BRVLAN_COMPRESSED |
 			   RTEXT_FILTER_MRP |
 			   RTEXT_FILTER_CFM_CONFIG |
-			   RTEXT_FILTER_CFM_STATUS)) {
+			   RTEXT_FILTER_CFM_STATUS |
+			   RTEXT_FILTER_MST)) {
 		af = nla_nest_start_noflag(skb, IFLA_AF_SPEC);
 		if (!af)
 			goto nla_put_failure;
@@ -564,7 +568,28 @@ static int br_fill_ifinfo(struct sk_buff *skb,
 		nla_nest_end(skb, cfm_nest);
 	}
 
+	if ((filter_mask & RTEXT_FILTER_MST) &&
+	    br_opt_get(br, BROPT_MST_ENABLED) && port) {
+		const struct net_bridge_vlan_group *vg = nbp_vlan_group(port);
+		struct nlattr *mst_nest;
+		int err;
+
+		if (!vg || !vg->num_vlans)
+			goto done;
+
+		mst_nest = nla_nest_start(skb, IFLA_BRIDGE_MST);
+		if (!mst_nest)
+			goto nla_put_failure;
+
+		err = br_mst_fill_info(skb, vg);
+		if (err)
+			goto nla_put_failure;
+
+		nla_nest_end(skb, mst_nest);
+	}
+
 done:
+
 	if (af)
 		nla_nest_end(skb, af);
 	nlmsg_end(skb, nlh);
@@ -803,6 +828,23 @@ static int br_afspec(struct net_bridge *br,
 			if (err)
 				return err;
 			break;
+		case IFLA_BRIDGE_MST:
+			if (!p) {
+				NL_SET_ERR_MSG(extack,
+					       "MST states can only be set on bridge ports");
+				return -EINVAL;
+			}
+
+			if (cmd != RTM_SETLINK) {
+				NL_SET_ERR_MSG(extack,
+					       "MST states can only be set through RTM_SETLINK");
+				return -EINVAL;
+			}
+
+			err = br_mst_process(p, attr, extack);
+			if (err)
+				return err;
+			break;
 		}
 	}
 
diff --git a/net/bridge/br_private.h b/net/bridge/br_private.h
index 3978e1d9ffb5..18ccc3d5d296 100644
--- a/net/bridge/br_private.h
+++ b/net/bridge/br_private.h
@@ -1784,6 +1784,11 @@ int br_mst_vlan_set_msti(struct net_bridge_vlan *v, u16 msti);
 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);
+size_t br_mst_info_size(const struct net_bridge_vlan_group *vg);
+int br_mst_fill_info(struct sk_buff *skb,
+		     const struct net_bridge_vlan_group *vg);
+int br_mst_process(struct net_bridge_port *p, const struct nlattr *mst_attr,
+		   struct netlink_ext_ack *extack);
 #else
 static inline bool br_mst_is_enabled(struct net_bridge *br)
 {
@@ -1801,6 +1806,24 @@ static inline int br_mst_set_enabled(struct net_bridge *br, bool on,
 {
 	return -EOPNOTSUPP;
 }
+
+static inline size_t br_mst_info_size(const struct net_bridge_vlan_group *vg)
+{
+	return 0;
+}
+
+static inline int br_mst_fill_info(struct sk_buff *skb,
+				   const struct net_bridge_vlan_group *vg)
+{
+	return -EOPNOTSUPP;
+}
+
+static inline int br_mst_process(struct net_bridge_port *p,
+				 const struct nlattr *mst_attr,
+				 struct netlink_ext_ack *extack)
+{
+	return -EOPNOTSUPP;
+}
 #endif
 
 struct nf_br_ops {