Bluetooth: Fix sending write_le_host_supporte for LE-only controllers

The Bluetooth Core Specification (4.0) defines the Write LE Host
Supported HCI command as only available for controllers supporting
BR/EDR. This is further reflected in the Read Local Extended Features
HCI command also not being available for LE-only controllers. In other
words, host-side LE support is implicit for single-mode LE controllers
and doesn't have explicit HCI-level enablement.

This patch ensures that the LE setting is always exposed as enabled
through mgmt and returns a "rejected" response if user space tries to
toggle the setting. The patch also ensures that Write LE Host Supported
is never sent for LE-only controllers.
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Gustavo Padovan <gustavo.padovan@collabora.co.uk>

net/bluetooth/hci_core.c

@@ -377,6 +377,8 @@ static void bredr_setup(struct hci_request *req)
 
 static void le_setup(struct hci_request *req)
 {
+	struct hci_dev *hdev = req->hdev;
+
 	/* Read LE Buffer Size */
 	hci_req_add(req, HCI_OP_LE_READ_BUFFER_SIZE, 0, NULL);
 
@@ -391,6 +393,10 @@ static void le_setup(struct hci_request *req)
 
 	/* Read LE Supported States */
 	hci_req_add(req, HCI_OP_LE_READ_SUPPORTED_STATES, 0, NULL);
+
+	/* LE-only controllers have LE implicitly enabled */
+	if (!lmp_bredr_capable(hdev))
+		set_bit(HCI_LE_ENABLED, &hdev->dev_flags);
 }
 
 static u8 hci_get_inquiry_mode(struct hci_dev *hdev)
@@ -574,6 +580,10 @@ static void hci_set_le_support(struct hci_request *req)
 	struct hci_dev *hdev = req->hdev;
 	struct hci_cp_write_le_host_supported cp;
 
+	/* LE-only devices do not support explicit enablement */
+	if (!lmp_bredr_capable(hdev))
+		return;
+
 	memset(&cp, 0, sizeof(cp));
 
 	if (test_bit(HCI_LE_ENABLED, &hdev->dev_flags)) {

net/bluetooth/mgmt.c

@@ -1351,6 +1351,11 @@ static int set_le(struct sock *sk, struct hci_dev *hdev, void *data, u16 len)
 		return cmd_status(sk, hdev->id, MGMT_OP_SET_LE,
 				  MGMT_STATUS_INVALID_PARAMS);
 
+	/* LE-only devices do not allow toggling LE on/off */
+	if (!lmp_bredr_capable(hdev))
+		return cmd_status(sk, hdev->id, MGMT_OP_SET_LE,
+				  MGMT_STATUS_REJECTED);
+
 	hci_dev_lock(hdev);
 
 	val = !!cp->val;
@@ -3347,7 +3352,8 @@ static int powered_update_hci(struct hci_dev *hdev)
 		hci_req_add(&req, HCI_OP_WRITE_SSP_MODE, 1, &ssp);
 	}
 
-	if (test_bit(HCI_LE_ENABLED, &hdev->dev_flags)) {
+	if (test_bit(HCI_LE_ENABLED, &hdev->dev_flags) &&
+	    lmp_bredr_capable(hdev)) {
 		struct hci_cp_write_le_host_supported cp;
 
 		cp.le = 1;