ieee802154: Add support for user scanning requests

The ieee802154 layer should be able to scan a set of channels in order
to look for beacons advertizing PANs. Supporting this involves adding
two user commands: triggering scans and aborting scans. The user should
also be notified when a new beacon is received and also upon scan
termination.

A scan request structure is created to list the requirements and to be
accessed asynchronously when changing channels or receiving beacons.

Mac layers may now implement the ->trigger_scan() and ->abort_scan()
hooks.

Co-developed-by: David Girault <david.girault@qorvo.com>
Signed-off-by: David Girault <david.girault@qorvo.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Acked-by: Alexander Aring <aahringo@redhat.com>
Link: https://lore.kernel.org/r/20230103165644.432209-2-miquel.raynal@bootlin.com
Signed-off-by: Stefan Schmidt <stefan@datenfreihafen.org>

include/linux/ieee802154.h

@@ -44,6 +44,9 @@
 #define IEEE802154_SHORT_ADDR_LEN	2
 #define IEEE802154_PAN_ID_LEN		2
 
+/* Duration in superframe order */
+#define IEEE802154_MAX_SCAN_DURATION	14
+#define IEEE802154_ACTIVE_SCAN_DURATION	15
 #define IEEE802154_LIFS_PERIOD		40
 #define IEEE802154_SIFS_PERIOD		12
 #define IEEE802154_MAX_SIFS_FRAME_SIZE	18

include/net/cfg802154.h

@@ -18,6 +18,7 @@
 
 struct wpan_phy;
 struct wpan_phy_cca;
+struct cfg802154_scan_request;
 
 #ifdef CONFIG_IEEE802154_NL802154_EXPERIMENTAL
 struct ieee802154_llsec_device_key;
@@ -67,6 +68,10 @@ struct cfg802154_ops {
 				struct wpan_dev *wpan_dev, bool mode);
 	int	(*set_ackreq_default)(struct wpan_phy *wpan_phy,
 				      struct wpan_dev *wpan_dev, bool ackreq);
+	int	(*trigger_scan)(struct wpan_phy *wpan_phy,
+				struct cfg802154_scan_request *request);
+	int	(*abort_scan)(struct wpan_phy *wpan_phy,
+			      struct wpan_dev *wpan_dev);
 #ifdef CONFIG_IEEE802154_NL802154_EXPERIMENTAL
 	void	(*get_llsec_table)(struct wpan_phy *wpan_phy,
 				   struct wpan_dev *wpan_dev,
@@ -278,6 +283,26 @@ struct ieee802154_coord_desc {
 	bool gts_permit;
 };
 
+/**
+ * struct cfg802154_scan_request - Scan request
+ *
+ * @type: type of scan to be performed
+ * @page: page on which to perform the scan
+ * @channels: channels in te %page to be scanned
+ * @duration: time spent on each channel, calculated with:
+ *            aBaseSuperframeDuration * (2 ^ duration + 1)
+ * @wpan_dev: the wpan device on which to perform the scan
+ * @wpan_phy: the wpan phy on which to perform the scan
+ */
+struct cfg802154_scan_request {
+	enum nl802154_scan_types type;
+	u8 page;
+	u32 channels;
+	u8 duration;
+	struct wpan_dev *wpan_dev;
+	struct wpan_phy *wpan_phy;
+};
+
 struct ieee802154_llsec_key_id {
 	u8 mode;
 	u8 id;

include/net/nl802154.h

@@ -73,6 +73,9 @@ enum nl802154_commands {
 	NL802154_CMD_DEL_SEC_LEVEL,
 
 	NL802154_CMD_SCAN_EVENT,
+	NL802154_CMD_TRIGGER_SCAN,
+	NL802154_CMD_ABORT_SCAN,
+	NL802154_CMD_SCAN_DONE,
 
 	/* add new commands above here */
 
@@ -134,6 +137,13 @@ enum nl802154_attrs {
 	NL802154_ATTR_NETNS_FD,
 
 	NL802154_ATTR_COORDINATOR,
+	NL802154_ATTR_SCAN_TYPE,
+	NL802154_ATTR_SCAN_FLAGS,
+	NL802154_ATTR_SCAN_CHANNELS,
+	NL802154_ATTR_SCAN_PREAMBLE_CODES,
+	NL802154_ATTR_SCAN_MEAN_PRF,
+	NL802154_ATTR_SCAN_DURATION,
+	NL802154_ATTR_SCAN_DONE_REASON,
 
 	/* add attributes here, update the policy in nl802154.c */
 
@@ -259,6 +269,54 @@ enum nl802154_coord {
 	NL802154_COORD_MAX,
 };
 
+/**
+ * enum nl802154_scan_types - Scan types
+ *
+ * @__NL802154_SCAN_INVALID: scan type number 0 is reserved
+ * @NL802154_SCAN_ED: An ED scan allows a device to obtain a measure of the peak
+ *	energy in each requested channel
+ * @NL802154_SCAN_ACTIVE: Locate any coordinator transmitting Beacon frames using
+ *	a Beacon Request command
+ * @NL802154_SCAN_PASSIVE: Locate any coordinator transmitting Beacon frames
+ * @NL802154_SCAN_ORPHAN: Relocate coordinator following a loss of synchronisation
+ * @NL802154_SCAN_ENHANCED_ACTIVE: Same as Active using Enhanced Beacon Request
+ *	command instead of Beacon Request command
+ * @NL802154_SCAN_RIT_PASSIVE: Passive scan for RIT Data Request command frames
+ *	instead of Beacon frames
+ * @NL802154_SCAN_ATTR_MAX: Maximum SCAN attribute number
+ */
+enum nl802154_scan_types {
+	__NL802154_SCAN_INVALID,
+	NL802154_SCAN_ED,
+	NL802154_SCAN_ACTIVE,
+	NL802154_SCAN_PASSIVE,
+	NL802154_SCAN_ORPHAN,
+	NL802154_SCAN_ENHANCED_ACTIVE,
+	NL802154_SCAN_RIT_PASSIVE,
+
+	/* keep last */
+	NL802154_SCAN_ATTR_MAX,
+};
+
+/**
+ * enum nl802154_scan_done_reasons - End of scan reasons
+ *
+ * @__NL802154_SCAN_DONE_REASON_INVALID: scan done reason number 0 is reserved.
+ * @NL802154_SCAN_DONE_REASON_FINISHED: The scan just finished naturally after
+ *	going through all the requested and possible (complex) channels.
+ * @NL802154_SCAN_DONE_REASON_ABORTED: The scan was aborted upon user request.
+ *	a Beacon Request command
+ * @NL802154_SCAN_DONE_REASON_MAX: Maximum scan done reason attribute number.
+ */
+enum nl802154_scan_done_reasons {
+	__NL802154_SCAN_DONE_REASON_INVALID,
+	NL802154_SCAN_DONE_REASON_FINISHED,
+	NL802154_SCAN_DONE_REASON_ABORTED,
+
+	/* keep last */
+	NL802154_SCAN_DONE_REASON_MAX,
+};
+
 /**
  * enum nl802154_cca_modes - cca modes
  *

net/ieee802154/nl802154.c

@@ -221,6 +221,13 @@ static const struct nla_policy nl802154_policy[NL802154_ATTR_MAX+1] = {
 
 	[NL802154_ATTR_COORDINATOR] = { .type = NLA_NESTED },
 
+	[NL802154_ATTR_SCAN_TYPE] = { .type = NLA_U8 },
+	[NL802154_ATTR_SCAN_CHANNELS] = { .type = NLA_U32 },
+	[NL802154_ATTR_SCAN_PREAMBLE_CODES] = { .type = NLA_U64 },
+	[NL802154_ATTR_SCAN_MEAN_PRF] = { .type = NLA_U8 },
+	[NL802154_ATTR_SCAN_DURATION] = { .type = NLA_U8 },
+	[NL802154_ATTR_SCAN_DONE_REASON] = { .type = NLA_U8 },
+
 #ifdef CONFIG_IEEE802154_NL802154_EXPERIMENTAL
 	[NL802154_ATTR_SEC_ENABLED] = { .type = NLA_U8, },
 	[NL802154_ATTR_SEC_OUT_LEVEL] = { .type = NLA_U32, },
@@ -1384,6 +1391,203 @@ int nl802154_scan_event(struct wpan_phy *wpan_phy, struct wpan_dev *wpan_dev,
 }
 EXPORT_SYMBOL_GPL(nl802154_scan_event);
 
+static int nl802154_trigger_scan(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 cfg802154_scan_request *request;
+	u8 type;
+	int err;
+
+	/* Monitors are not allowed to perform scans */
+	if (wpan_dev->iftype == NL802154_IFTYPE_MONITOR)
+		return -EPERM;
+
+	request = kzalloc(sizeof(*request), GFP_KERNEL);
+	if (!request)
+		return -ENOMEM;
+
+	request->wpan_dev = wpan_dev;
+	request->wpan_phy = wpan_phy;
+
+	type = nla_get_u8(info->attrs[NL802154_ATTR_SCAN_TYPE]);
+	switch (type) {
+	case NL802154_SCAN_PASSIVE:
+		request->type = type;
+		break;
+	default:
+		pr_err("Unsupported scan type: %d\n", type);
+		err = -EINVAL;
+		goto free_request;
+	}
+
+	if (info->attrs[NL802154_ATTR_PAGE]) {
+		request->page = nla_get_u8(info->attrs[NL802154_ATTR_PAGE]);
+		if (request->page > IEEE802154_MAX_PAGE) {
+			pr_err("Invalid page %d > %d\n",
+			       request->page, IEEE802154_MAX_PAGE);
+			err = -EINVAL;
+			goto free_request;
+		}
+	} else {
+		/* Use current page by default */
+		request->page = wpan_phy->current_page;
+	}
+
+	if (info->attrs[NL802154_ATTR_SCAN_CHANNELS]) {
+		request->channels = nla_get_u32(info->attrs[NL802154_ATTR_SCAN_CHANNELS]);
+		if (request->channels >= BIT(IEEE802154_MAX_CHANNEL + 1)) {
+			pr_err("Invalid channels bitfield %x ≥ %lx\n",
+			       request->channels,
+			       BIT(IEEE802154_MAX_CHANNEL + 1));
+			err = -EINVAL;
+			goto free_request;
+		}
+	} else {
+		/* Scan all supported channels by default */
+		request->channels = wpan_phy->supported.channels[request->page];
+	}
+
+	if (info->attrs[NL802154_ATTR_SCAN_PREAMBLE_CODES] ||
+	    info->attrs[NL802154_ATTR_SCAN_MEAN_PRF]) {
+		pr_err("Preamble codes and mean PRF not supported yet\n");
+		err = -EINVAL;
+		goto free_request;
+	}
+
+	if (info->attrs[NL802154_ATTR_SCAN_DURATION]) {
+		request->duration = nla_get_u8(info->attrs[NL802154_ATTR_SCAN_DURATION]);
+		if (request->duration > IEEE802154_MAX_SCAN_DURATION) {
+			pr_err("Duration is out of range\n");
+			err = -EINVAL;
+			goto free_request;
+		}
+	} else {
+		/* Use maximum duration order by default */
+		request->duration = IEEE802154_MAX_SCAN_DURATION;
+	}
+
+	if (wpan_dev->netdev)
+		dev_hold(wpan_dev->netdev);
+
+	err = rdev_trigger_scan(rdev, request);
+	if (err) {
+		pr_err("Failure starting scanning (%d)\n", err);
+		goto free_device;
+	}
+
+	return 0;
+
+free_device:
+	if (wpan_dev->netdev)
+		dev_put(wpan_dev->netdev);
+free_request:
+	kfree(request);
+
+	return err;
+}
+
+static int nl802154_prep_scan_msg(struct sk_buff *msg,
+				  struct cfg802154_registered_device *rdev,
+				  struct wpan_dev *wpan_dev, u32 portid,
+				  u32 seq, int flags, u8 cmd, u8 arg)
+{
+	void *hdr;
+
+	hdr = nl802154hdr_put(msg, portid, seq, flags, cmd);
+	if (!hdr)
+		return -ENOBUFS;
+
+	if (nla_put_u32(msg, NL802154_ATTR_WPAN_PHY, rdev->wpan_phy_idx))
+		goto nla_put_failure;
+
+	if (wpan_dev->netdev &&
+	    nla_put_u32(msg, NL802154_ATTR_IFINDEX, wpan_dev->netdev->ifindex))
+		goto nla_put_failure;
+
+	if (nla_put_u64_64bit(msg, NL802154_ATTR_WPAN_DEV,
+			      wpan_dev_id(wpan_dev), NL802154_ATTR_PAD))
+		goto nla_put_failure;
+
+	if (cmd == NL802154_CMD_SCAN_DONE &&
+	    nla_put_u8(msg, NL802154_ATTR_SCAN_DONE_REASON, arg))
+		goto nla_put_failure;
+
+	genlmsg_end(msg, hdr);
+
+	return 0;
+
+nla_put_failure:
+	genlmsg_cancel(msg, hdr);
+
+	return -EMSGSIZE;
+}
+
+static int nl802154_send_scan_msg(struct cfg802154_registered_device *rdev,
+				  struct wpan_dev *wpan_dev, u8 cmd, u8 arg)
+{
+	struct sk_buff *msg;
+	int ret;
+
+	msg = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
+	if (!msg)
+		return -ENOMEM;
+
+	ret = nl802154_prep_scan_msg(msg, rdev, wpan_dev, 0, 0, 0, cmd, arg);
+	if (ret < 0) {
+		nlmsg_free(msg);
+		return ret;
+	}
+
+	return genlmsg_multicast_netns(&nl802154_fam,
+				       wpan_phy_net(&rdev->wpan_phy), msg, 0,
+				       NL802154_MCGRP_SCAN, GFP_KERNEL);
+}
+
+int nl802154_scan_started(struct wpan_phy *wpan_phy, struct wpan_dev *wpan_dev)
+{
+	struct cfg802154_registered_device *rdev = wpan_phy_to_rdev(wpan_phy);
+	int err;
+
+	/* Ignore errors when there are no listeners */
+	err = nl802154_send_scan_msg(rdev, wpan_dev, NL802154_CMD_TRIGGER_SCAN, 0);
+	if (err == -ESRCH)
+		err = 0;
+
+	return err;
+}
+EXPORT_SYMBOL_GPL(nl802154_scan_started);
+
+int nl802154_scan_done(struct wpan_phy *wpan_phy, struct wpan_dev *wpan_dev,
+		       enum nl802154_scan_done_reasons reason)
+{
+	struct cfg802154_registered_device *rdev = wpan_phy_to_rdev(wpan_phy);
+	int err;
+
+	/* Ignore errors when there are no listeners */
+	err = nl802154_send_scan_msg(rdev, wpan_dev, NL802154_CMD_SCAN_DONE, reason);
+	if (err == -ESRCH)
+		err = 0;
+
+	if (wpan_dev->netdev)
+		dev_put(wpan_dev->netdev);
+
+	return err;
+}
+EXPORT_SYMBOL_GPL(nl802154_scan_done);
+
+static int nl802154_abort_scan(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;
+
+	/* Resources are released in the notification helper above */
+	return rdev_abort_scan(rdev, wpan_dev);
+}
+
 #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 },
@@ -2474,6 +2678,22 @@ static const struct genl_ops nl802154_ops[] = {
 		.internal_flags = NL802154_FLAG_NEED_NETDEV |
 				  NL802154_FLAG_NEED_RTNL,
 	},
+	{
+		.cmd = NL802154_CMD_TRIGGER_SCAN,
+		.doit = nl802154_trigger_scan,
+		.flags = GENL_ADMIN_PERM,
+		.internal_flags = NL802154_FLAG_NEED_NETDEV |
+				  NL802154_FLAG_CHECK_NETDEV_UP |
+				  NL802154_FLAG_NEED_RTNL,
+	},
+	{
+		.cmd = NL802154_CMD_ABORT_SCAN,
+		.doit = nl802154_abort_scan,
+		.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/nl802154.h

@@ -6,5 +6,8 @@ int nl802154_init(void);
 void nl802154_exit(void);
 int nl802154_scan_event(struct wpan_phy *wpan_phy, struct wpan_dev *wpan_dev,
 			struct ieee802154_coord_desc *desc);
+int nl802154_scan_started(struct wpan_phy *wpan_phy, struct wpan_dev *wpan_dev);
+int nl802154_scan_done(struct wpan_phy *wpan_phy, struct wpan_dev *wpan_dev,
+		       enum nl802154_scan_done_reasons reason);
 
 #endif /* __IEEE802154_NL802154_H */