Bluetooth: Allow Microsoft extension to indicate curve validation

Some controllers don't support the Simple Pairing Options feature that
can indicate the support for P-192 and P-256 public key validation.
However they might support the Microsoft vendor extension that can
indicate the validiation capability as well.

Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

include/net/bluetooth/hci_core.h

@@ -584,6 +584,7 @@ struct hci_dev {
 #if IS_ENABLED(CONFIG_BT_MSFTEXT)
 	__u16			msft_opcode;
 	void			*msft_data;
+	bool			msft_curve_validity;
 #endif
 
 #if IS_ENABLED(CONFIG_BT_AOSPEXT)

net/bluetooth/mgmt.c

@@ -3730,8 +3730,11 @@ static int read_controller_cap(struct sock *sk, struct hci_dev *hdev,
 
 	/* When the Read Simple Pairing Options command is supported, then
 	 * the remote public key validation is supported.
+	 *
+	 * Alternatively, when Microsoft extensions are available, they can
+	 * indicate support for public key validation as well.
 	 */
-	if (hdev->commands[41] & 0x08)
+	if ((hdev->commands[41] & 0x08) || hdev->msft_curve_validity)
 		flags |= 0x01;	/* Remote public key validation (BR/EDR) */
 
 	flags |= 0x02;		/* Remote public key validation (LE) */

net/bluetooth/msft.c

@@ -142,6 +142,9 @@ static bool read_supported_features(struct hci_dev *hdev,
 	msft->evt_prefix_len = rp->evt_prefix_len;
 	msft->features = __le64_to_cpu(rp->features);
 
+	if (msft->features & MSFT_FEATURE_MASK_CURVE_VALIDITY)
+		hdev->msft_curve_validity = true;
+
 	kfree_skb(skb);
 	return true;