net: bridge: vlan options: add support for tunnel mapping set/del

This patch adds support for manipulating vlan/tunnel mappings. The
tunnel ids are globally unique and are one per-vlan. There were two
trickier issues - first in order to support vlan ranges we have to
compute the current tunnel id in the following way:
 - base tunnel id (attr) + current vlan id - starting vlan id
This is in line how the old API does vlan/tunnel mapping with ranges. We
already have the vlan range present, so it's redundant to add another
attribute for the tunnel range end. It's simply base tunnel id + vlan
range. And second to support removing mappings we need an out-of-band way
to tell the option manipulating function because there are no
special/reserved tunnel id values, so we use a vlan flag to denote the
operation is tunnel mapping removal.

Signed-off-by: Nikolay Aleksandrov <nikolay@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/uapi/linux/if_bridge.h

@@ -131,6 +131,7 @@ enum {
 #define BRIDGE_VLAN_INFO_RANGE_END	(1<<4) /* VLAN is end of vlan range */
 #define BRIDGE_VLAN_INFO_BRENTRY	(1<<5) /* Global bridge VLAN entry */
 #define BRIDGE_VLAN_INFO_ONLY_OPTS	(1<<6) /* Skip create/delete/flags */
+#define BRIDGE_VLAN_INFO_REMOVE_TUN	(1<<7) /* Remove tunnel mapping */
 
 struct bridge_vlan_info {
 	__u16 flags;

net/bridge/br_netlink_tunnel.c

@@ -193,8 +193,8 @@ static const struct nla_policy vlan_tunnel_policy[IFLA_BRIDGE_VLAN_TUNNEL_MAX +
 	[IFLA_BRIDGE_VLAN_TUNNEL_FLAGS] = { .type = NLA_U16 },
 };
 
-static int br_vlan_tunnel_info(const struct net_bridge_port *p, int cmd,
-			       u16 vid, u32 tun_id, bool *changed)
+int br_vlan_tunnel_info(const struct net_bridge_port *p, int cmd,
+			u16 vid, u32 tun_id, bool *changed)
 {
 	int err = 0;
 

net/bridge/br_private_tunnel.h

@@ -45,6 +45,8 @@ int br_handle_egress_vlan_tunnel(struct sk_buff *skb,
 				 struct net_bridge_vlan *vlan);
 bool vlan_tunid_inrange(const struct net_bridge_vlan *v_curr,
 			const struct net_bridge_vlan *v_last);
+int br_vlan_tunnel_info(const struct net_bridge_port *p, int cmd,
+			u16 vid, u32 tun_id, bool *changed);
 #else
 static inline int vlan_tunnel_init(struct net_bridge_vlan_group *vg)
 {

net/bridge/br_vlan.c

@@ -1839,6 +1839,7 @@ static const struct nla_policy br_vlan_db_policy[BRIDGE_VLANDB_ENTRY_MAX + 1] =
 					    .len = sizeof(struct bridge_vlan_info) },
 	[BRIDGE_VLANDB_ENTRY_RANGE]	= { .type = NLA_U16 },
 	[BRIDGE_VLANDB_ENTRY_STATE]	= { .type = NLA_U8 },
+	[BRIDGE_VLANDB_ENTRY_TUNNEL_ID] = { .type = NLA_U32 },
 };
 
 static int br_vlan_rtm_process_one(struct net_device *dev,

net/bridge/br_vlan_options.c

@@ -85,6 +85,40 @@ static int br_vlan_modify_state(struct net_bridge_vlan_group *vg,
 	return 0;
 }
 
+static int br_vlan_modify_tunnel(const struct net_bridge_port *p,
+				 struct net_bridge_vlan *v,
+				 struct nlattr **tb,
+				 bool *changed,
+				 struct netlink_ext_ack *extack)
+{
+	struct bridge_vlan_info *vinfo;
+	int cmdmap;
+	u32 tun_id;
+
+	if (!p) {
+		NL_SET_ERR_MSG_MOD(extack, "Can't modify tunnel mapping of non-port vlans");
+		return -EINVAL;
+	}
+	if (!(p->flags & BR_VLAN_TUNNEL)) {
+		NL_SET_ERR_MSG_MOD(extack, "Port doesn't have tunnel flag set");
+		return -EINVAL;
+	}
+
+	/* vlan info attribute is guaranteed by br_vlan_rtm_process_one */
+	vinfo = nla_data(tb[BRIDGE_VLANDB_ENTRY_INFO]);
+	cmdmap = vinfo->flags & BRIDGE_VLAN_INFO_REMOVE_TUN ? RTM_DELLINK :
+							      RTM_SETLINK;
+	/* when working on vlan ranges this represents the starting tunnel id */
+	tun_id = nla_get_u32(tb[BRIDGE_VLANDB_ENTRY_TUNNEL_ID]);
+	/* tunnel ids are mapped to each vlan in increasing order,
+	 * the starting vlan is in BRIDGE_VLANDB_ENTRY_INFO and v is the
+	 * current vlan, so we compute: tun_id + v - vinfo->vid
+	 */
+	tun_id += v->vid - vinfo->vid;
+
+	return br_vlan_tunnel_info(p, cmdmap, v->vid, tun_id, changed);
+}
+
 static int br_vlan_process_one_opts(const struct net_bridge *br,
 				    const struct net_bridge_port *p,
 				    struct net_bridge_vlan_group *vg,
@@ -103,6 +137,11 @@ static int br_vlan_process_one_opts(const struct net_bridge *br,
 		if (err)
 			return err;
 	}
+	if (tb[BRIDGE_VLANDB_ENTRY_TUNNEL_ID]) {
+		err = br_vlan_modify_tunnel(p, v, tb, changed, extack);
+		if (err)
+			return err;
+	}
 
 	return 0;
 }