Bluetooth: Add Kconfig option to disable HCI ECDH support

This adds Kconfig option to disable HCI ECDH support.
It will compile out ECDH related code, especially HCI event handlers.

Signed-off-by: Mariusz Skamra <mariusz.skamra@codecoup.pl>

subsys/bluetooth/host/Kconfig

@@ -273,6 +273,7 @@ config BT_SMP
 	select TINYCRYPT_AES
 	select TINYCRYPT_AES_CMAC
 	select BT_RPA
+	select BT_ECC
 	help
 	  This option enables support for the Security Manager Protocol
 	  (SMP), making it possible to pair devices over LE.
@@ -488,12 +489,17 @@ config BT_ID_MAX
 
 endif # BT_HCI_HOST
 
+config BT_ECC
+	bool "Enable ECDH key generation support"
+	help
+	  This option adds support for ECDH HCI commands.
+
 config BT_TINYCRYPT_ECC
 	bool "Use TinyCrypt library for ECDH"
 	select TINYCRYPT
 	select TINYCRYPT_ECC_DH
-	depends on BT_HCI_RAW || BT_HCI_HOST
+	depends on BT_ECC && (BT_HCI_RAW || BT_HCI_HOST)
-	default y if BT_CTLR && (BT_SMP || BT_MESH_PROV)
+	default y if BT_CTLR
 	help
 	  If this option is set TinyCrypt library is used for emulating the
 	  ECDH HCI commands and events needed by e.g. LE Secure Connections.

subsys/bluetooth/host/hci_core.c

@@ -83,9 +83,11 @@ static bt_ready_cb_t ready_cb;
 
 static bt_le_scan_cb_t *scan_dev_found_cb;
 
+#if defined(CONFIG_BT_ECC)
 static u8_t pub_key[64];
 static struct bt_pub_key_cb *pub_key_cb;
 static bt_dh_key_cb_t dh_key_cb;
+#endif /* CONFIG_BT_ECC */
 
 #if defined(CONFIG_BT_BREDR)
 static bt_br_discovery_cb_t *discovery_cb;
@@ -2958,6 +2960,7 @@ done:
 }
 #endif /* CONFIG_BT_SMP */
 
+#if defined(CONFIG_BT_ECC)
 static void le_pkey_complete(struct net_buf *buf)
 {
 	struct bt_hci_evt_le_p256_public_key_complete *evt = (void *)buf->data;
@@ -2988,6 +2991,7 @@ static void le_dhkey_complete(struct net_buf *buf)
 		dh_key_cb = NULL;
 	}
 }
+#endif /* CONFIG_BT_ECC */
 
 static void hci_reset_complete(struct net_buf *buf)
 {
@@ -3324,12 +3328,14 @@ static void hci_le_meta_event(struct net_buf *buf)
 		le_ltk_request(buf);
 		break;
 #endif /* CONFIG_BT_SMP */
+#if defined(CONFIG_BT_ECC)
 	case BT_HCI_EVT_LE_P256_PUBLIC_KEY_COMPLETE:
 		le_pkey_complete(buf);
 		break;
 	case BT_HCI_EVT_LE_GENERATE_DHKEY_COMPLETE:
 		le_dhkey_complete(buf);
 		break;
+#endif /* CONFIG_BT_SMP */
 #if defined(CONFIG_BT_OBSERVER)
 	case BT_HCI_EVT_LE_ADVERTISING_REPORT:
 		le_adv_report(buf);
@@ -5740,6 +5746,7 @@ u16_t bt_hci_get_cmd_opcode(struct net_buf *buf)
 	return cmd(buf)->opcode;
 }
 
+#if defined(CONFIG_BT_ECC)
 int bt_pub_key_gen(struct bt_pub_key_cb *new_cb)
 {
 	struct bt_pub_key_cb *cb;
@@ -5825,6 +5832,7 @@ int bt_dh_key_gen(const u8_t remote_pk[64], bt_dh_key_cb_t cb)
 
 	return 0;
 }
+#endif /* CONFIG_BT_ECC */
 
 #if defined(CONFIG_BT_BREDR)
 int bt_br_oob_get_local(struct bt_br_oob *oob)

subsys/bluetooth/host/mesh/Kconfig

@@ -22,6 +22,7 @@ if BT_MESH
 # Virtual option enabled whenever Generic Provisioning layer is needed
 config BT_MESH_PROV
 	bool
+	select BT_ECC
 
 config BT_MESH_PB_ADV
 	bool "Provisioning support using the advertising bearer (PB-ADV)"