[PATCH wpan-next v3 07/11] mac802154: Handle association requests from peers

[Miquel Raynal <miquel.raynal@bootlin.com>]

Coordinators may have to handle association requests from peers which
want to join the PAN. The logic involves:
- Acknowledging the request (done by hardware)
- If requested, a random short address that is free on this PAN should
  be chosen for the device.
- Sending an association response with the short address allocated for
  the peer and expecting it to be ack'ed.

If anything fails during this procedure, the peer is considered not
associated.

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
---
 include/net/cfg802154.h         |   7 ++
 include/net/ieee802154_netdev.h |   6 ++
 net/ieee802154/core.c           |   7 ++
 net/ieee802154/pan.c            |  30 +++++++
 net/mac802154/ieee802154_i.h    |   2 +
 net/mac802154/rx.c              |   8 ++
 net/mac802154/scan.c            | 145 ++++++++++++++++++++++++++++++++
 7 files changed, 205 insertions(+)

diff --git a/include/net/cfg802154.h b/include/net/cfg802154.h
index ce649ebc3b19..f0d0e0cb4ad8 100644
--- a/include/net/cfg802154.h
+++ b/include/net/cfg802154.h
@@ -582,4 +582,11 @@ struct ieee802154_pan_device *
 cfg802154_device_is_child(struct wpan_dev *wpan_dev,
 			  struct ieee802154_addr *target);
 
+/**
+ * cfg802154_get_free_short_addr - Get a free address among the known devices
+ * @wpan_dev: the wpan device
+ * @return: a random short address expectedly unused on our PAN
+ */
+__le16 cfg802154_get_free_short_addr(struct wpan_dev *wpan_dev);
+
 #endif /* __NET_CFG802154_H */
diff --git a/include/net/ieee802154_netdev.h b/include/net/ieee802154_netdev.h
index 16194356cfe7..4de858f9929e 100644
--- a/include/net/ieee802154_netdev.h
+++ b/include/net/ieee802154_netdev.h
@@ -211,6 +211,12 @@ struct ieee802154_association_req_frame {
 	struct ieee802154_assoc_req_pl assoc_req_pl;
 };
 
+struct ieee802154_association_resp_frame {
+	struct ieee802154_hdr mhr;
+	struct ieee802154_mac_cmd_pl mac_pl;
+	struct ieee802154_assoc_resp_pl assoc_resp_pl;
+};
+
 struct ieee802154_disassociation_notif_frame {
 	struct ieee802154_hdr mhr;
 	struct ieee802154_mac_cmd_pl mac_pl;
diff --git a/net/ieee802154/core.c b/net/ieee802154/core.c
index a08d75dd56ad..1670a71327a7 100644
--- a/net/ieee802154/core.c
+++ b/net/ieee802154/core.c
@@ -200,11 +200,18 @@ EXPORT_SYMBOL(wpan_phy_free);
 
 static void cfg802154_free_peer_structures(struct wpan_dev *wpan_dev)
 {
+	struct ieee802154_pan_device *child, *tmp;
+
 	mutex_lock(&wpan_dev->association_lock);
 
 	kfree(wpan_dev->parent);
 	wpan_dev->parent = NULL;
 
+	list_for_each_entry_safe(child, tmp, &wpan_dev->children, node) {
+		list_del(&child->node);
+		kfree(child);
+	}
+
 	mutex_unlock(&wpan_dev->association_lock);
 }
 
diff --git a/net/ieee802154/pan.c b/net/ieee802154/pan.c
index 78b5099591ae..8a16bb4c52a7 100644
--- a/net/ieee802154/pan.c
+++ b/net/ieee802154/pan.c
@@ -75,3 +75,33 @@ cfg802154_device_is_child(struct wpan_dev *wpan_dev,
 	return NULL;
 }
 EXPORT_SYMBOL_GPL(cfg802154_device_is_child);
+
+__le16 cfg802154_get_free_short_addr(struct wpan_dev *wpan_dev)
+{
+	struct ieee802154_pan_device *child;
+	__le16 addr;
+
+	lockdep_assert_held(&wpan_dev->association_lock);
+
+	do {
+		get_random_bytes(&addr, 2);
+		if (addr == cpu_to_le16(IEEE802154_ADDR_SHORT_BROADCAST) ||
+		    addr == cpu_to_le16(IEEE802154_ADDR_SHORT_UNSPEC))
+			continue;
+
+		if (wpan_dev->short_addr == addr)
+			continue;
+
+		if (wpan_dev->parent && wpan_dev->parent->short_addr == addr)
+			continue;
+
+		list_for_each_entry(child, &wpan_dev->children, node)
+			if (child->short_addr == addr)
+				continue;
+
+		break;
+	} while (1);
+
+	return addr;
+}
+EXPORT_SYMBOL_GPL(cfg802154_get_free_short_addr);
diff --git a/net/mac802154/ieee802154_i.h b/net/mac802154/ieee802154_i.h
index 92252f86c69c..432bfa87249e 100644
--- a/net/mac802154/ieee802154_i.h
+++ b/net/mac802154/ieee802154_i.h
@@ -318,6 +318,8 @@ static inline bool mac802154_is_associating(struct ieee802154_local *local)
 int mac802154_send_disassociation_notif(struct ieee802154_sub_if_data *sdata,
 					struct ieee802154_pan_device *target,
 					u8 reason);
+int mac802154_process_association_req(struct ieee802154_sub_if_data *sdata,
+				      struct sk_buff *skb);
 
 /* interface handling */
 int ieee802154_iface_init(void);
diff --git a/net/mac802154/rx.c b/net/mac802154/rx.c
index d0e08613a36b..96040b63a4fc 100644
--- a/net/mac802154/rx.c
+++ b/net/mac802154/rx.c
@@ -102,6 +102,14 @@ void mac802154_rx_mac_cmd_worker(struct work_struct *work)
 		mac802154_process_association_resp(mac_pkt->sdata, mac_pkt->skb);
 		break;
 
+	case IEEE802154_CMD_ASSOCIATION_REQ:
+		dev_dbg(&mac_pkt->sdata->dev->dev, "processing ASSOC REQ\n");
+		if (mac_pkt->sdata->wpan_dev.iftype != NL802154_IFTYPE_COORD)
+			break;
+
+		mac802154_process_association_req(mac_pkt->sdata, mac_pkt->skb);
+		break;
+
 	default:
 		break;
 	}
diff --git a/net/mac802154/scan.c b/net/mac802154/scan.c
index e2f2e1235ec6..76f04550aabb 100644
--- a/net/mac802154/scan.c
+++ b/net/mac802154/scan.c
@@ -697,3 +697,148 @@ int mac802154_send_disassociation_notif(struct ieee802154_sub_if_data *sdata,
 	dev_dbg(&sdata->dev->dev, "DISASSOC ACK received from %8phC\n", &teaddr);
 	return 0;
 }
+
+static int
+mac802154_send_association_resp_locked(struct ieee802154_sub_if_data *sdata,
+				       struct ieee802154_pan_device *target,
+				       struct ieee802154_assoc_resp_pl *assoc_resp_pl)
+{
+	u64 teaddr = swab64((__force u64)target->extended_addr);
+	struct ieee802154_association_resp_frame frame = {};
+	struct ieee802154_local *local = sdata->local;
+	struct wpan_dev *wpan_dev = &sdata->wpan_dev;
+	struct sk_buff *skb;
+	int ret;
+
+	frame.mhr.fc.type = IEEE802154_FC_TYPE_MAC_CMD;
+	frame.mhr.fc.security_enabled = 0;
+	frame.mhr.fc.frame_pending = 0;
+	frame.mhr.fc.ack_request = 1; /* We always expect an ack here */
+	frame.mhr.fc.intra_pan = 1;
+	frame.mhr.fc.dest_addr_mode = IEEE802154_EXTENDED_ADDRESSING;
+	frame.mhr.fc.version = IEEE802154_2003_STD;
+	frame.mhr.fc.source_addr_mode = IEEE802154_EXTENDED_ADDRESSING;
+	frame.mhr.source.mode = IEEE802154_ADDR_LONG;
+	frame.mhr.source.extended_addr = wpan_dev->extended_addr;
+	frame.mhr.dest.mode = IEEE802154_ADDR_LONG;
+	frame.mhr.dest.pan_id = wpan_dev->pan_id;
+	frame.mhr.dest.extended_addr = target->extended_addr;
+	frame.mhr.seq = atomic_inc_return(&wpan_dev->dsn) & 0xFF;
+	frame.mac_pl.cmd_id = IEEE802154_CMD_ASSOCIATION_RESP;
+
+	skb = alloc_skb(IEEE802154_MAC_CMD_SKB_SZ + sizeof(*assoc_resp_pl),
+			GFP_KERNEL);
+	if (!skb)
+		return -ENOBUFS;
+
+	skb->dev = sdata->dev;
+
+	ret = ieee802154_mac_cmd_push(skb, &frame, assoc_resp_pl,
+				      sizeof(*assoc_resp_pl));
+	if (ret) {
+		kfree_skb(skb);
+		return ret;
+	}
+
+	ret = ieee802154_mlme_tx_locked(local, sdata, skb);
+	if (ret) {
+		dev_warn(&sdata->dev->dev,
+			 "No ASSOC RESP ACK received from %8phC\n", &teaddr);
+		if (ret > 0)
+			ret = (ret == IEEE802154_NO_ACK) ? -EREMOTEIO : -EIO;
+		return ret;
+	}
+
+	return 0;
+}
+
+int mac802154_process_association_req(struct ieee802154_sub_if_data *sdata,
+				      struct sk_buff *skb)
+{
+	struct wpan_dev *wpan_dev = &sdata->wpan_dev;
+	struct ieee802154_addr *src = &mac_cb(skb)->source;
+	struct ieee802154_addr *dest = &mac_cb(skb)->dest;
+	struct ieee802154_assoc_resp_pl assoc_resp_pl = {};
+	struct ieee802154_assoc_req_pl assoc_req_pl;
+	struct ieee802154_pan_device *child, *exchild;
+	struct ieee802154_addr tmp = {};
+	u64 ceaddr;
+	int ret;
+
+	if (skb->len != sizeof(assoc_req_pl))
+		return -EINVAL;
+
+	if (unlikely(src->mode != IEEE802154_EXTENDED_ADDRESSING))
+		return -EINVAL;
+
+	if (unlikely(dest->pan_id != wpan_dev->pan_id))
+		return -ENODEV;
+
+	if (dest->mode == IEEE802154_EXTENDED_ADDRESSING &&
+	    unlikely(dest->extended_addr != wpan_dev->extended_addr))
+		return -ENODEV;
+	else if (dest->mode == IEEE802154_SHORT_ADDRESSING &&
+		 unlikely(dest->short_addr != wpan_dev->short_addr))
+		return -ENODEV;
+
+	mutex_lock(&wpan_dev->association_lock);
+
+	memcpy(&assoc_req_pl, skb->data, sizeof(assoc_req_pl));
+	if (assoc_req_pl.assoc_type) {
+		dev_err(&skb->dev->dev, "Fast associations not supported yet\n");
+		ret = -EOPNOTSUPP;
+		goto unlock;
+	}
+
+	child = kzalloc(sizeof(*child), GFP_KERNEL);
+	if (!child) {
+		ret = -ENOMEM;
+		goto unlock;
+	}
+
+	child->extended_addr = src->extended_addr;
+	child->mode = IEEE802154_EXTENDED_ADDRESSING;
+	ceaddr = swab64((__force u64)child->extended_addr);
+
+	assoc_resp_pl.status = IEEE802154_ASSOCIATION_SUCCESSFUL;
+	if (assoc_req_pl.alloc_addr) {
+		assoc_resp_pl.short_addr = cfg802154_get_free_short_addr(wpan_dev);
+		child->mode = IEEE802154_SHORT_ADDRESSING;
+	} else {
+		assoc_resp_pl.short_addr = cpu_to_le16(IEEE802154_ADDR_SHORT_UNSPEC);
+	}
+	child->short_addr = assoc_resp_pl.short_addr;
+	dev_dbg(&sdata->dev->dev,
+		"Accepting ASSOC REQ from child %8phC, providing short address 0x%04x\n",
+		&ceaddr, le16_to_cpu(child->short_addr));
+
+	ret = mac802154_send_association_resp_locked(sdata, child, &assoc_resp_pl);
+	if (ret) {
+		kfree(child);
+		goto unlock;
+	}
+
+	dev_dbg(&sdata->dev->dev,
+		"Successful association with new child %8phC\n", &ceaddr);
+
+	/* Ensure this child is not already associated (might happen due to
+	 * retransmissions), in this case drop the ex structure.
+	 */
+	tmp.mode = child->mode;
+	if (tmp.mode == IEEE802154_SHORT_ADDRESSING)
+		tmp.short_addr = child->short_addr;
+	else
+		tmp.extended_addr = child->extended_addr;
+	exchild = cfg802154_device_is_child(wpan_dev, &tmp);
+	if (exchild) {
+		dev_dbg(&sdata->dev->dev,
+			"Child %8phC was already known\n", &ceaddr);
+		list_del(&exchild->node);
+	}
+
+	list_add(&child->node, &wpan_dev->children);
+
+unlock:
+	mutex_unlock(&wpan_dev->association_lock);
+	return ret;
+}
-- 
2.34.1