Bluetooth: Add support for Read Local Simple Pairing Options

With the Read Local Simple Pairing Options command it is possible to
retrieve the support for max encryption key size supported by the
controller and also if the controller correctly verifies the ECDH public
key during pairing.
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
Reviewed-by: Alain Michaud <alainm@chromium.org>
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>

include/net/bluetooth/hci.h

@@ -1275,6 +1275,13 @@ struct hci_rp_read_data_block_size {
 
 #define HCI_OP_READ_LOCAL_CODECS	0x100b
 
+#define HCI_OP_READ_LOCAL_PAIRING_OPTS	0x100c
+struct hci_rp_read_local_pairing_opts {
+	__u8     status;
+	__u8     pairing_opts;
+	__u8     max_key_size;
+} __packed;
+
 #define HCI_OP_READ_PAGE_SCAN_ACTIVITY	0x0c1b
 struct hci_rp_read_page_scan_activity {
 	__u8     status;

include/net/bluetooth/hci_core.h

@@ -312,6 +312,8 @@ struct hci_dev {
 	__u16		conn_info_max_age;
 	__u16		auth_payload_timeout;
 	__u8		min_enc_key_size;
+	__u8		max_enc_key_size;
+	__u8		pairing_opts;
 	__u8		ssp_debug_mode;
 	__u8		hw_error_code;
 	__u32		clock;

net/bluetooth/hci_core.c

@@ -827,6 +827,10 @@ static int hci_init4_req(struct hci_request *req, unsigned long opt)
 	if (hdev->commands[29] & 0x20)
 		hci_req_add(req, HCI_OP_READ_LOCAL_CODECS, 0, NULL);
 
+	/* Read local pairing options if the HCI command is supported */
+	if (hdev->commands[41] & 0x08)
+		hci_req_add(req, HCI_OP_READ_LOCAL_PAIRING_OPTS, 0, NULL);
+
 	/* Get MWS transport configuration if the HCI command is supported */
 	if (hdev->commands[30] & 0x08)
 		hci_req_add(req, HCI_OP_GET_MWS_TRANSPORT_CONFIG, 0, NULL);

net/bluetooth/hci_event.c

@@ -747,6 +747,23 @@ static void hci_cc_read_bd_addr(struct hci_dev *hdev, struct sk_buff *skb)
 		bacpy(&hdev->setup_addr, &rp->bdaddr);
 }
 
+static void hci_cc_read_local_pairing_opts(struct hci_dev *hdev,
+					   struct sk_buff *skb)
+{
+	struct hci_rp_read_local_pairing_opts *rp = (void *) skb->data;
+
+	BT_DBG("%s status 0x%2.2x", hdev->name, rp->status);
+
+	if (rp->status)
+		return;
+
+	if (hci_dev_test_flag(hdev, HCI_SETUP) ||
+	    hci_dev_test_flag(hdev, HCI_CONFIG)) {
+		hdev->pairing_opts = rp->pairing_opts;
+		hdev->max_enc_key_size = rp->max_key_size;
+	}
+}
+
 static void hci_cc_read_page_scan_activity(struct hci_dev *hdev,
 					   struct sk_buff *skb)
 {
@@ -3343,6 +3360,10 @@ static void hci_cmd_complete_evt(struct hci_dev *hdev, struct sk_buff *skb,
 		hci_cc_read_bd_addr(hdev, skb);
 		break;
 
+	case HCI_OP_READ_LOCAL_PAIRING_OPTS:
+		hci_cc_read_local_pairing_opts(hdev, skb);
+		break;
+
 	case HCI_OP_READ_PAGE_SCAN_ACTIVITY:
 		hci_cc_read_page_scan_activity(hdev, skb);
 		break;