[Bluetooth] Use ACL config stage to retrieve remote features

The Bluetooth technology introduces new features on a regular basis
and for some of them it is important that the hardware on both sides
support them. For features like Simple Pairing it is important that
the host stacks on both sides have switched this feature on. To make
valid decisions, a config stage during ACL link establishment has been
introduced that retrieves remote features and if needed also the remote
extended features (known as remote host features) before signalling
this link as connected.

This change introduces full reference counting of incoming and outgoing
ACL links and the Bluetooth core will disconnect both if no owner of it
is present. To better handle interoperability during the pairing phase
the disconnect timeout for incoming connections has been increased to
10 seconds. This is five times more than for outgoing connections.
Signed-off-by: NMarcel Holtmann <marcel@holtmann.org>

include/net/bluetooth/hci.h

@@ -180,6 +180,8 @@ enum {
 
 #define LMP_SNIFF_SUBR	0x02
 
+#define LMP_SIMPLE_PAIR	0x08
+
 /* Connection modes */
 #define HCI_CM_ACTIVE	0x0000
 #define HCI_CM_HOLD	0x0001

include/net/bluetooth/hci_core.h

@@ -348,7 +348,7 @@ static inline void hci_conn_put(struct hci_conn *conn)
 			if (conn->state == BT_CONNECTED) {
 				timeo = msecs_to_jiffies(HCI_DISCONN_TIMEOUT);
 				if (!conn->out)
-					timeo *= 2;
+					timeo *= 5;
 			} else
 				timeo = msecs_to_jiffies(10);
 		} else
@@ -463,6 +463,7 @@ void hci_conn_del_sysfs(struct hci_conn *conn);
 #define lmp_sniff_capable(dev)     ((dev)->features[0] & LMP_SNIFF)
 #define lmp_sniffsubr_capable(dev) ((dev)->features[5] & LMP_SNIFF_SUBR)
 #define lmp_esco_capable(dev)      ((dev)->features[3] & LMP_ESCO)
+#define lmp_ssp_capable(dev)       ((dev)->features[6] & LMP_SIMPLE_PAIR)
 
 /* ----- HCI protocols ----- */
 struct hci_proto {

net/bluetooth/hci_conn.c

@@ -170,11 +170,13 @@ static void hci_conn_timeout(unsigned long arg)
 
 	switch (conn->state) {
 	case BT_CONNECT:
+	case BT_CONNECT2:
 		if (conn->type == ACL_LINK)
 			hci_acl_connect_cancel(conn);
 		else
 			hci_acl_disconn(conn, 0x13);
 		break;
+	case BT_CONFIG:
 	case BT_CONNECTED:
 		hci_acl_disconn(conn, 0x13);
 		break;

net/bluetooth/hci_core.c

@@ -1283,9 +1283,12 @@ static inline struct hci_conn *hci_low_sent(struct hci_dev *hdev, __u8 type, int
 		struct hci_conn *c;
 		c = list_entry(p, struct hci_conn, list);
 
-		if (c->type != type || c->state != BT_CONNECTED
-				|| skb_queue_empty(&c->data_q))
+		if (c->type != type || skb_queue_empty(&c->data_q))
 			continue;
+
+		if (c->state != BT_CONNECTED && c->state != BT_CONFIG)
+			continue;
+
 		num++;
 
 		if (c->sent < min) {

net/bluetooth/hci_event.c

@@ -624,6 +624,62 @@ static void hci_cs_remote_name_req(struct hci_dev *hdev, __u8 status)
 	BT_DBG("%s status 0x%x", hdev->name, status);
 }
 
+static void hci_cs_read_remote_features(struct hci_dev *hdev, __u8 status)
+{
+	struct hci_cp_read_remote_features *cp;
+	struct hci_conn *conn;
+
+	BT_DBG("%s status 0x%x", hdev->name, status);
+
+	if (!status)
+		return;
+
+	cp = hci_sent_cmd_data(hdev, HCI_OP_READ_REMOTE_FEATURES);
+	if (!cp)
+		return;
+
+	hci_dev_lock(hdev);
+
+	conn = hci_conn_hash_lookup_handle(hdev, __le16_to_cpu(cp->handle));
+	if (conn) {
+		if (conn->state == BT_CONFIG) {
+			conn->state = BT_CONNECTED;
+			hci_proto_connect_cfm(conn, status);
+			hci_conn_put(conn);
+		}
+	}
+
+	hci_dev_unlock(hdev);
+}
+
+static void hci_cs_read_remote_ext_features(struct hci_dev *hdev, __u8 status)
+{
+	struct hci_cp_read_remote_ext_features *cp;
+	struct hci_conn *conn;
+
+	BT_DBG("%s status 0x%x", hdev->name, status);
+
+	if (!status)
+		return;
+
+	cp = hci_sent_cmd_data(hdev, HCI_OP_READ_REMOTE_EXT_FEATURES);
+	if (!cp)
+		return;
+
+	hci_dev_lock(hdev);
+
+	conn = hci_conn_hash_lookup_handle(hdev, __le16_to_cpu(cp->handle));
+	if (conn) {
+		if (conn->state == BT_CONFIG) {
+			conn->state = BT_CONNECTED;
+			hci_proto_connect_cfm(conn, status);
+			hci_conn_put(conn);
+		}
+	}
+
+	hci_dev_unlock(hdev);
+}
+
 static void hci_cs_setup_sync_conn(struct hci_dev *hdev, __u8 status)
 {
 	struct hci_cp_setup_sync_conn *cp;
@@ -759,7 +815,12 @@ static inline void hci_conn_complete_evt(struct hci_dev *hdev, struct sk_buff *s
 
 	if (!ev->status) {
 		conn->handle = __le16_to_cpu(ev->handle);
-		conn->state  = BT_CONNECTED;
+
+		if (conn->type == ACL_LINK) {
+			conn->state = BT_CONFIG;
+			hci_conn_hold(conn);
+		} else
+			conn->state = BT_CONNECTED;
 
 		if (test_bit(HCI_AUTH, &hdev->flags))
 			conn->link_mode |= HCI_LM_AUTH;
@@ -771,7 +832,8 @@ static inline void hci_conn_complete_evt(struct hci_dev *hdev, struct sk_buff *s
 		if (conn->type == ACL_LINK) {
 			struct hci_cp_read_remote_features cp;
 			cp.handle = ev->handle;
-			hci_send_cmd(hdev, HCI_OP_READ_REMOTE_FEATURES, sizeof(cp), &cp);
+			hci_send_cmd(hdev, HCI_OP_READ_REMOTE_FEATURES,
+							sizeof(cp), &cp);
 		}
 
 		/* Set packet type for incoming connection */
@@ -781,10 +843,6 @@ static inline void hci_conn_complete_evt(struct hci_dev *hdev, struct sk_buff *s
 			cp.pkt_type = cpu_to_le16(conn->pkt_type);
 			hci_send_cmd(hdev, HCI_OP_CHANGE_CONN_PTYPE,
 							sizeof(cp), &cp);
-		} else {
-			/* Update disconnect timer */
-			hci_conn_hold(conn);
-			hci_conn_put(conn);
 		}
 	} else
 		conn->state = BT_CLOSED;
@@ -804,9 +862,10 @@ static inline void hci_conn_complete_evt(struct hci_dev *hdev, struct sk_buff *s
 		}
 	}
 
-	hci_proto_connect_cfm(conn, ev->status);
-	if (ev->status)
+	if (ev->status) {
+		hci_proto_connect_cfm(conn, ev->status);
 		hci_conn_del(conn);
+	}
 
 unlock:
 	hci_dev_unlock(hdev);
@@ -1006,14 +1065,29 @@ static inline void hci_remote_features_evt(struct hci_dev *hdev, struct sk_buff
 
 	BT_DBG("%s status %d", hdev->name, ev->status);
 
-	if (ev->status)
-		return;
-
 	hci_dev_lock(hdev);
 
 	conn = hci_conn_hash_lookup_handle(hdev, __le16_to_cpu(ev->handle));
-	if (conn)
-		memcpy(conn->features, ev->features, 8);
+	if (conn) {
+		if (!ev->status)
+			memcpy(conn->features, ev->features, 8);
+
+		if (conn->state == BT_CONFIG) {
+			if (!ev->status && lmp_ssp_capable(hdev) &&
+						lmp_ssp_capable(conn)) {
+				struct hci_cp_read_remote_ext_features cp;
+				cp.handle = ev->handle;
+				cp.page = 0x01;
+				hci_send_cmd(hdev,
+					HCI_OP_READ_REMOTE_EXT_FEATURES,
+							sizeof(cp), &cp);
+			} else {
+				conn->state = BT_CONNECTED;
+				hci_proto_connect_cfm(conn, ev->status);
+				hci_conn_put(conn);
+			}
+		}
+	}
 
 	hci_dev_unlock(hdev);
 }
@@ -1180,6 +1254,14 @@ static inline void hci_cmd_status_evt(struct hci_dev *hdev, struct sk_buff *skb)
 		hci_cs_remote_name_req(hdev, ev->status);
 		break;
 
+	case HCI_OP_READ_REMOTE_FEATURES:
+		hci_cs_read_remote_features(hdev, ev->status);
+		break;
+
+	case HCI_OP_READ_REMOTE_EXT_FEATURES:
+		hci_cs_read_remote_ext_features(hdev, ev->status);
+		break;
+
 	case HCI_OP_SETUP_SYNC_CONN:
 		hci_cs_setup_sync_conn(hdev, ev->status);
 		break;
@@ -1422,19 +1504,24 @@ static inline void hci_remote_ext_features_evt(struct hci_dev *hdev, struct sk_b
 
 	BT_DBG("%s", hdev->name);
 
-	if (ev->status || ev->page != 0x01)
-		return;
-
 	hci_dev_lock(hdev);
 
 	conn = hci_conn_hash_lookup_handle(hdev, __le16_to_cpu(ev->handle));
 	if (conn) {
-		struct inquiry_entry *ie;
+		if (!ev->status && ev->page == 0x01) {
+			struct inquiry_entry *ie;
 
-		if ((ie = hci_inquiry_cache_lookup(hdev, &conn->dst)))
-			ie->data.ssp_mode = (ev->features[0] & 0x01);
+			if ((ie = hci_inquiry_cache_lookup(hdev, &conn->dst)))
+				ie->data.ssp_mode = (ev->features[0] & 0x01);
 
-		conn->ssp_mode = (ev->features[0] & 0x01);
+			conn->ssp_mode = (ev->features[0] & 0x01);
+		}
+
+		if (conn->state == BT_CONFIG) {
+			conn->state = BT_CONNECTED;
+			hci_proto_connect_cfm(conn, ev->status);
+			hci_conn_put(conn);
+		}
 	}
 
 	hci_dev_unlock(hdev);