ieee802154: Add support for user disassociation requests

A device may decide at some point to disassociate from a PAN, let's
introduce a netlink command for this purpose.

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Acked-by: Stefan Schmidt <stefan@datenfreihafen.org>
Acked-by: Alexander Aring <aahringo@redhat.com>
Link: https://lore.kernel.org/linux-wpan/20230927181214.129346-6-miquel.raynal@bootlin.com

include/net/cfg802154.h

@@ -81,6 +81,9 @@ struct cfg802154_ops {
 	int	(*associate)(struct wpan_phy *wpan_phy,
 			     struct wpan_dev *wpan_dev,
 			     struct ieee802154_addr *coord);
+	int	(*disassociate)(struct wpan_phy *wpan_phy,
+				struct wpan_dev *wpan_dev,
+				struct ieee802154_addr *target);
 #ifdef CONFIG_IEEE802154_NL802154_EXPERIMENTAL
 	void	(*get_llsec_table)(struct wpan_phy *wpan_phy,
 				   struct wpan_dev *wpan_dev,

include/net/ieee802154_netdev.h

@@ -177,6 +177,11 @@ enum ieee802154_association_status {
 	IEEE802154_FAST_ASSOCIATION_SUCCESSFUL = 0x80,
 };
 
+enum ieee802154_disassociation_reason {
+	IEEE802154_COORD_WISHES_DEVICE_TO_LEAVE = 0x1,
+	IEEE802154_DEVICE_WISHES_TO_LEAVE = 0x2,
+};
+
 struct ieee802154_hdr {
 	struct ieee802154_hdr_fc fc;
 	u8 seq;
@@ -206,6 +211,12 @@ struct ieee802154_association_req_frame {
 	struct ieee802154_assoc_req_pl assoc_req_pl;
 };
 
+struct ieee802154_disassociation_notif_frame {
+	struct ieee802154_hdr mhr;
+	struct ieee802154_mac_cmd_pl mac_pl;
+	u8 disassoc_pl;
+};
+
 /* pushes hdr onto the skb. fields of hdr->fc that can be calculated from
  * the contents of hdr will be, and the actual value of those bits in
  * hdr->fc will be ignored. this includes the INTRA_PAN bit and the frame

include/net/nl802154.h

@@ -79,6 +79,7 @@ enum nl802154_commands {
 	NL802154_CMD_SEND_BEACONS,
 	NL802154_CMD_STOP_BEACONS,
 	NL802154_CMD_ASSOCIATE,
+	NL802154_CMD_DISASSOCIATE,
 
 	/* add new commands above here */
 

net/ieee802154/nl802154.c

@@ -1663,6 +1663,39 @@ static int nl802154_associate(struct sk_buff *skb, struct genl_info *info)
 	return err;
 }
 
+static int nl802154_disassociate(struct sk_buff *skb, struct genl_info *info)
+{
+	struct cfg802154_registered_device *rdev = info->user_ptr[0];
+	struct net_device *dev = info->user_ptr[1];
+	struct wpan_dev *wpan_dev = dev->ieee802154_ptr;
+	struct wpan_phy *wpan_phy = &rdev->wpan_phy;
+	struct ieee802154_addr target;
+
+	if (wpan_phy->flags & WPAN_PHY_FLAG_DATAGRAMS_ONLY) {
+		NL_SET_ERR_MSG(info->extack, "PHY only supports datagrams");
+		return -EOPNOTSUPP;
+	}
+
+	target.pan_id = wpan_dev->pan_id;
+
+	if (info->attrs[NL802154_ATTR_EXTENDED_ADDR]) {
+		target.mode = IEEE802154_ADDR_LONG;
+		target.extended_addr = nla_get_le64(info->attrs[NL802154_ATTR_EXTENDED_ADDR]);
+	} else if (info->attrs[NL802154_ATTR_SHORT_ADDR]) {
+		target.mode = IEEE802154_ADDR_SHORT;
+		target.short_addr = nla_get_le16(info->attrs[NL802154_ATTR_SHORT_ADDR]);
+	} else {
+		NL_SET_ERR_MSG(info->extack, "Device address is missing");
+		return -EINVAL;
+	}
+
+	mutex_lock(&wpan_dev->association_lock);
+	rdev_disassociate(rdev, wpan_dev, &target);
+	mutex_unlock(&wpan_dev->association_lock);
+
+	return 0;
+}
+
 #ifdef CONFIG_IEEE802154_NL802154_EXPERIMENTAL
 static const struct nla_policy nl802154_dev_addr_policy[NL802154_DEV_ADDR_ATTR_MAX + 1] = {
 	[NL802154_DEV_ADDR_ATTR_PAN_ID] = { .type = NLA_U16 },
@@ -2792,6 +2825,14 @@ static const struct genl_ops nl802154_ops[] = {
 				  NL802154_FLAG_CHECK_NETDEV_UP |
 				  NL802154_FLAG_NEED_RTNL,
 	},
+	{
+		.cmd = NL802154_CMD_DISASSOCIATE,
+		.doit = nl802154_disassociate,
+		.flags = GENL_ADMIN_PERM,
+		.internal_flags = NL802154_FLAG_NEED_NETDEV |
+				  NL802154_FLAG_CHECK_NETDEV_UP |
+				  NL802154_FLAG_NEED_RTNL,
+	},
 #ifdef CONFIG_IEEE802154_NL802154_EXPERIMENTAL
 	{
 		.cmd = NL802154_CMD_SET_SEC_PARAMS,

net/ieee802154/rdev-ops.h

@@ -280,6 +280,21 @@ static inline int rdev_associate(struct cfg802154_registered_device *rdev,
 	return ret;
 }
 
+static inline int rdev_disassociate(struct cfg802154_registered_device *rdev,
+				    struct wpan_dev *wpan_dev,
+				    struct ieee802154_addr *target)
+{
+	int ret;
+
+	if (!rdev->ops->disassociate)
+		return -EOPNOTSUPP;
+
+	trace_802154_rdev_disassociate(&rdev->wpan_phy, wpan_dev, target);
+	ret = rdev->ops->disassociate(&rdev->wpan_phy, wpan_dev, target);
+	trace_802154_rdev_return_int(&rdev->wpan_phy, ret);
+	return ret;
+}
+
 #ifdef CONFIG_IEEE802154_NL802154_EXPERIMENTAL
 /* TODO this is already a nl802154, so move into ieee802154 */
 static inline void

net/ieee802154/trace.h

@@ -375,6 +375,25 @@ TRACE_EVENT(802154_rdev_associate,
 		  WPAN_PHY_PR_ARG, WPAN_DEV_PR_ARG, __entry->addr)
 );
 
+TRACE_EVENT(802154_rdev_disassociate,
+	TP_PROTO(struct wpan_phy *wpan_phy,
+		 struct wpan_dev *wpan_dev,
+		 struct ieee802154_addr *target),
+	TP_ARGS(wpan_phy, wpan_dev, target),
+	TP_STRUCT__entry(
+		WPAN_PHY_ENTRY
+		WPAN_DEV_ENTRY
+		__field(__le64, addr)
+	),
+	TP_fast_assign(
+		WPAN_PHY_ASSIGN;
+		WPAN_DEV_ASSIGN;
+		__entry->addr = target->extended_addr;
+	),
+	TP_printk(WPAN_PHY_PR_FMT ", " WPAN_DEV_PR_FMT ", disassociating with: 0x%llx",
+		  WPAN_PHY_PR_ARG, WPAN_DEV_PR_ARG, __entry->addr)
+);
+
 TRACE_EVENT(802154_rdev_return_int,
 	TP_PROTO(struct wpan_phy *wpan_phy, int ret),
 	TP_ARGS(wpan_phy, ret),