subsys/bluetooth/mesh/prov_device.c

/*
 * Copyright (c) 2017 Intel Corporation
 * Copyright (c) 2020 Lingao Meng
 *
 * SPDX-License-Identifier: Apache-2.0
 */

#include <zephyr.h>
#include <errno.h>
#include <sys/atomic.h>
#include <sys/util.h>
#include <sys/byteorder.h>

#include <tinycrypt/constants.h>
#include <tinycrypt/ecc.h>
#include <tinycrypt/ecc_dh.h>

#include <net/buf.h>
#include <bluetooth/bluetooth.h>
#include <bluetooth/conn.h>
#include <bluetooth/mesh.h>
#include <bluetooth/uuid.h>

#define BT_DBG_ENABLED IS_ENABLED(CONFIG_BT_MESH_DEBUG_PROV_DEVICE)
#define LOG_MODULE_NAME bt_mesh_prov_device
#include "common/log.h"

#include "host/ecc.h"
#include "host/testing.h"

#include "crypto.h"
#include "adv.h"
#include "mesh.h"
#include "net.h"
#include "rpl.h"
#include "beacon.h"
#include "access.h"
#include "foundation.h"
#include "proxy.h"
#include "pb_gatt_srv.h"
#include "prov.h"
#include "settings.h"

static void send_pub_key(void);
static void pub_key_ready(const uint8_t *pkey);

static int reset_state(void)
{
	return bt_mesh_prov_reset_state(pub_key_ready);
}

static void prov_send_fail_msg(uint8_t err)
{
	PROV_BUF(buf, PDU_LEN_FAILED);

	BT_DBG("%u", err);

	bt_mesh_prov_link.expect = PROV_NO_PDU;

	bt_mesh_prov_buf_init(&buf, PROV_FAILED);
	net_buf_simple_add_u8(&buf, err);

	if (bt_mesh_prov_send(&buf, NULL)) {
		BT_ERR("Failed to send Provisioning Failed message");
	}
}

static void prov_fail(uint8_t reason)
{
	/* According to Bluetooth Mesh Specification v1.0.1, Section 5.4.4, the
	 * provisioner just closes the link when something fails, while the
	 * provisionee sends the fail message, and waits for the provisioner to
	 * close the link.
	 */
	prov_send_fail_msg(reason);
}

static void prov_invite(const uint8_t *data)
{
	PROV_BUF(buf, PDU_LEN_CAPABILITIES);

	BT_DBG("Attention Duration: %u seconds", data[0]);

	if (data[0]) {
		bt_mesh_attention(NULL, data[0]);
	}

	memcpy(bt_mesh_prov_link.conf_inputs.invite, data, PDU_LEN_INVITE);

	bt_mesh_prov_buf_init(&buf, PROV_CAPABILITIES);

	/* Number of Elements supported */
	net_buf_simple_add_u8(&buf, bt_mesh_elem_count());

	/* Supported algorithms - FIPS P-256 Eliptic Curve */
	net_buf_simple_add_be16(&buf, BIT(PROV_ALG_P256));

	/* Public Key Type */
	net_buf_simple_add_u8(&buf,
			      bt_mesh_prov->public_key_be == NULL ? PUB_KEY_NO_OOB : PUB_KEY_OOB);

	/* Static OOB Type */
	net_buf_simple_add_u8(&buf, bt_mesh_prov->static_val ? BIT(0) : 0x00);

	/* Output OOB Size */
	net_buf_simple_add_u8(&buf, bt_mesh_prov->output_size);

	/* Output OOB Action */
	net_buf_simple_add_be16(&buf, bt_mesh_prov->output_actions);

	/* Input OOB Size */
	net_buf_simple_add_u8(&buf, bt_mesh_prov->input_size);

	/* Input OOB Action */
	net_buf_simple_add_be16(&buf, bt_mesh_prov->input_actions);

	memcpy(bt_mesh_prov_link.conf_inputs.capabilities, &buf.data[1], PDU_LEN_CAPABILITIES);

	if (bt_mesh_prov_send(&buf, NULL)) {
		BT_ERR("Failed to send capabilities");
		return;
	}

	bt_mesh_prov_link.expect = PROV_START;
}

static void prov_start(const uint8_t *data)
{
	BT_DBG("Algorithm:   0x%02x", data[0]);
	BT_DBG("Public Key:  0x%02x", data[1]);
	BT_DBG("Auth Method: 0x%02x", data[2]);
	BT_DBG("Auth Action: 0x%02x", data[3]);
	BT_DBG("Auth Size:   0x%02x", data[4]);

	if (data[0] != PROV_ALG_P256) {
		BT_ERR("Unknown algorithm 0x%02x", data[0]);
		prov_fail(PROV_ERR_NVAL_FMT);
		return;
	}

	if (data[1] > PUB_KEY_OOB ||
	    (data[1] == PUB_KEY_OOB &&
	     (!IS_ENABLED(CONFIG_BT_MESH_PROV_OOB_PUBLIC_KEY) || !bt_mesh_prov->public_key_be))) {
		BT_ERR("Invalid public key type: 0x%02x", data[1]);
		prov_fail(PROV_ERR_NVAL_FMT);
		return;
	}

	atomic_set_bit_to(bt_mesh_prov_link.flags, OOB_PUB_KEY, data[1] == PUB_KEY_OOB);

	memcpy(bt_mesh_prov_link.conf_inputs.start, data, PDU_LEN_START);

	bt_mesh_prov_link.expect = PROV_PUB_KEY;
	bt_mesh_prov_link.oob_method = data[2];
	bt_mesh_prov_link.oob_action = data[3];
	bt_mesh_prov_link.oob_size = data[4];

	if (bt_mesh_prov_auth(false, data[2], data[3], data[4]) < 0) {
		BT_ERR("Invalid authentication method: 0x%02x; "
		       "action: 0x%02x; size: 0x%02x", data[2], data[3],
		       data[4]);
		prov_fail(PROV_ERR_NVAL_FMT);
	}

	if (atomic_test_bit(bt_mesh_prov_link.flags, OOB_STATIC_KEY)) {
		memcpy(bt_mesh_prov_link.auth + 16 - bt_mesh_prov->static_val_len,
		       bt_mesh_prov->static_val, bt_mesh_prov->static_val_len);
		(void)memset(bt_mesh_prov_link.auth, 0,
			     sizeof(bt_mesh_prov_link.auth) - bt_mesh_prov->static_val_len);
	}
}

static void send_confirm(void)
{
	PROV_BUF(cfm, PDU_LEN_CONFIRM);
	uint8_t *inputs = (uint8_t *)&bt_mesh_prov_link.conf_inputs;

	BT_DBG("ConfInputs[0]   %s", bt_hex(inputs, 64));
	BT_DBG("ConfInputs[64]  %s", bt_hex(&inputs[64], 64));
	BT_DBG("ConfInputs[128] %s", bt_hex(&inputs[128], 17));

	if (bt_mesh_prov_conf_salt(inputs, bt_mesh_prov_link.conf_salt)) {
		BT_ERR("Unable to generate confirmation salt");
		prov_fail(PROV_ERR_UNEXP_ERR);
		return;
	}

	BT_DBG("ConfirmationSalt: %s", bt_hex(bt_mesh_prov_link.conf_salt, 16));

	if (bt_mesh_prov_conf_key(bt_mesh_prov_link.dhkey, bt_mesh_prov_link.conf_salt,
				  bt_mesh_prov_link.conf_key)) {
		BT_ERR("Unable to generate confirmation key");
		prov_fail(PROV_ERR_UNEXP_ERR);
		return;
	}

	BT_DBG("ConfirmationKey: %s", bt_hex(bt_mesh_prov_link.conf_key, 16));

	if (bt_rand(bt_mesh_prov_link.rand, 16)) {
		BT_ERR("Unable to generate random number");
		prov_fail(PROV_ERR_UNEXP_ERR);
		return;
	}

	BT_DBG("LocalRandom: %s", bt_hex(bt_mesh_prov_link.rand, 16));

	bt_mesh_prov_buf_init(&cfm, PROV_CONFIRM);

	if (bt_mesh_prov_conf(bt_mesh_prov_link.conf_key, bt_mesh_prov_link.rand,
			      bt_mesh_prov_link.auth, net_buf_simple_add(&cfm, 16))) {
		BT_ERR("Unable to generate confirmation value");
		prov_fail(PROV_ERR_UNEXP_ERR);
		return;
	}

	if (bt_mesh_prov_send(&cfm, NULL)) {
		BT_ERR("Failed to send Provisioning Confirm");
		return;
	}

	bt_mesh_prov_link.expect = PROV_RANDOM;

}

static void send_input_complete(void)
{
	PROV_BUF(buf, PDU_LEN_INPUT_COMPLETE);

	bt_mesh_prov_buf_init(&buf, PROV_INPUT_COMPLETE);
	if (bt_mesh_prov_send(&buf, NULL)) {
		BT_ERR("Failed to send Provisioning Input Complete");
	}
	bt_mesh_prov_link.expect = PROV_CONFIRM;
}

static void public_key_sent(int err, void *cb_data)
{
	atomic_set_bit(bt_mesh_prov_link.flags, PUB_KEY_SENT);

	if (atomic_test_bit(bt_mesh_prov_link.flags, INPUT_COMPLETE)) {
		send_input_complete();
		return;
	}
}

static void start_auth(void)
{
	if (atomic_test_bit(bt_mesh_prov_link.flags, WAIT_NUMBER) ||
	    atomic_test_bit(bt_mesh_prov_link.flags, WAIT_STRING)) {
		bt_mesh_prov_link.expect = PROV_NO_PDU; /* Wait for input */
	} else {
		bt_mesh_prov_link.expect = PROV_CONFIRM;
	}
}

static void send_pub_key(void)
{
	PROV_BUF(buf, PDU_LEN_PUB_KEY);
	const uint8_t *key;

	key = bt_pub_key_get();
	if (!key) {
		BT_ERR("No public key available");
		prov_fail(PROV_ERR_UNEXP_ERR);
		return;
	}

	bt_mesh_prov_buf_init(&buf, PROV_PUB_KEY);

	/* Swap X and Y halves independently to big-endian */
	sys_memcpy_swap(net_buf_simple_add(&buf, BT_PUB_KEY_COORD_LEN), key, BT_PUB_KEY_COORD_LEN);
	sys_memcpy_swap(net_buf_simple_add(&buf, BT_PUB_KEY_COORD_LEN), &key[BT_PUB_KEY_COORD_LEN],
			BT_PUB_KEY_COORD_LEN);

	BT_DBG("Local Public Key: %s", bt_hex(buf.data + 1, BT_PUB_KEY_LEN));

	/* PublicKeyDevice */
	memcpy(bt_mesh_prov_link.conf_inputs.pub_key_device, &buf.data[1], PDU_LEN_PUB_KEY);

	if (bt_mesh_prov_send(&buf, public_key_sent)) {
		BT_ERR("Failed to send Public Key");
		return;
	}

	start_auth();
}

static void dh_key_gen_complete(void)
{
	BT_DBG("DHkey: %s", bt_hex(bt_mesh_prov_link.dhkey, BT_DH_KEY_LEN));

	if (!atomic_test_and_clear_bit(bt_mesh_prov_link.flags, WAIT_DH_KEY) &&
	    atomic_test_bit(bt_mesh_prov_link.flags, OOB_PUB_KEY)) {
		send_confirm();
	} else if (!atomic_test_bit(bt_mesh_prov_link.flags, OOB_PUB_KEY)) {
		send_pub_key();
	}
}

static void prov_dh_key_cb(const uint8_t dhkey[BT_DH_KEY_LEN])
{
	BT_DBG("%p", dhkey);

	if (!dhkey) {
		BT_ERR("DHKey generation failed");
		prov_fail(PROV_ERR_UNEXP_ERR);
		return;
	}

	sys_memcpy_swap(bt_mesh_prov_link.dhkey, dhkey, BT_DH_KEY_LEN);

	dh_key_gen_complete();
}

static void prov_dh_key_gen(void)
{
	const uint8_t *remote_pk;
	uint8_t remote_pk_le[BT_PUB_KEY_LEN];

	remote_pk = bt_mesh_prov_link.conf_inputs.pub_key_provisioner;

	if (IS_ENABLED(CONFIG_BT_MESH_PROV_OOB_PUBLIC_KEY) &&
	    atomic_test_bit(bt_mesh_prov_link.flags, OOB_PUB_KEY)) {
		if (uECC_valid_public_key(remote_pk, &curve_secp256r1)) {
			BT_ERR("Public key is not valid");
		} else if (uECC_shared_secret(remote_pk, bt_mesh_prov->private_key_be,
					      bt_mesh_prov_link.dhkey,
					      &curve_secp256r1) != TC_CRYPTO_SUCCESS) {
			BT_ERR("DHKey generation failed");
		} else {
			dh_key_gen_complete();
			return;
		}

		prov_fail(PROV_ERR_UNEXP_ERR);
		return;
	}

	/* Copy remote key in little-endian for bt_dh_key_gen().
	 * X and Y halves are swapped independently. The bt_dh_key_gen()
	 * will also take care of validating the remote public key.
	 */
	sys_memcpy_swap(remote_pk_le, remote_pk, BT_PUB_KEY_COORD_LEN);
	sys_memcpy_swap(&remote_pk_le[BT_PUB_KEY_COORD_LEN], &remote_pk[BT_PUB_KEY_COORD_LEN],
			BT_PUB_KEY_COORD_LEN);

	if (bt_dh_key_gen(remote_pk_le, prov_dh_key_cb)) {
		BT_ERR("Failed to generate DHKey");
		prov_fail(PROV_ERR_UNEXP_ERR);
	}
}

static void prov_pub_key(const uint8_t *data)
{
	BT_DBG("Remote Public Key: %s", bt_hex(data, BT_PUB_KEY_LEN));

	/* PublicKeyProvisioner */
	memcpy(bt_mesh_prov_link.conf_inputs.pub_key_provisioner, data, PDU_LEN_PUB_KEY);

	if (IS_ENABLED(CONFIG_BT_MESH_PROV_OOB_PUBLIC_KEY) &&
	    atomic_test_bit(bt_mesh_prov_link.flags, OOB_PUB_KEY)) {
		if (!bt_mesh_prov->public_key_be || !bt_mesh_prov->private_key_be) {
			BT_ERR("Public or private key is not ready");
			prov_fail(PROV_ERR_UNEXP_ERR);
			return;
		}

		/* No swap needed since user provides public key in big-endian */
		memcpy(bt_mesh_prov_link.conf_inputs.pub_key_device, bt_mesh_prov->public_key_be,
		       PDU_LEN_PUB_KEY);

		atomic_set_bit(bt_mesh_prov_link.flags, WAIT_DH_KEY);

		start_auth();
	} else if (!bt_pub_key_get()) {
		/* Clear retransmit timer */
		bt_mesh_prov_link.bearer->clear_tx();
		atomic_set_bit(bt_mesh_prov_link.flags, WAIT_PUB_KEY);
		BT_WARN("Waiting for local public key");
		return;
	}

	prov_dh_key_gen();
}

static void pub_key_ready(const uint8_t *pkey)
{
	if (!pkey) {
		BT_WARN("Public key not available");
		return;
	}

	BT_DBG("Local public key ready");

	if (atomic_test_and_clear_bit(bt_mesh_prov_link.flags, WAIT_PUB_KEY)) {
		prov_dh_key_gen();
	}
}

static void notify_input_complete(void)
{
	if (atomic_test_and_clear_bit(bt_mesh_prov_link.flags,
				      NOTIFY_INPUT_COMPLETE) &&
	    bt_mesh_prov->input_complete) {
		bt_mesh_prov->input_complete();
	}
}

static void send_random(void)
{
	PROV_BUF(rnd, PDU_LEN_RANDOM);

	bt_mesh_prov_buf_init(&rnd, PROV_RANDOM);
	net_buf_simple_add_mem(&rnd, bt_mesh_prov_link.rand, 16);

	if (bt_mesh_prov_send(&rnd, NULL)) {
		BT_ERR("Failed to send Provisioning Random");
		return;
	}

	bt_mesh_prov_link.expect = PROV_DATA;
}

static void prov_random(const uint8_t *data)
{
	uint8_t conf_verify[16];

	BT_DBG("Remote Random: %s", bt_hex(data, 16));
	if (!memcmp(data, bt_mesh_prov_link.rand, 16)) {
		BT_ERR("Random value is identical to ours, rejecting.");
		prov_fail(PROV_ERR_CFM_FAILED);
		return;
	}

	if (bt_mesh_prov_conf(bt_mesh_prov_link.conf_key, data,
			      bt_mesh_prov_link.auth, conf_verify)) {
		BT_ERR("Unable to calculate confirmation verification");
		prov_fail(PROV_ERR_UNEXP_ERR);
		return;
	}

	if (memcmp(conf_verify, bt_mesh_prov_link.conf, 16)) {
		BT_ERR("Invalid confirmation value");
		BT_DBG("Received:   %s", bt_hex(bt_mesh_prov_link.conf, 16));
		BT_DBG("Calculated: %s",  bt_hex(conf_verify, 16));
		prov_fail(PROV_ERR_CFM_FAILED);
		return;
	}

	if (bt_mesh_prov_salt(bt_mesh_prov_link.conf_salt, data,
			      bt_mesh_prov_link.rand, bt_mesh_prov_link.prov_salt)) {
		BT_ERR("Failed to generate provisioning salt");
		prov_fail(PROV_ERR_UNEXP_ERR);
		return;
	}

	BT_DBG("ProvisioningSalt: %s", bt_hex(bt_mesh_prov_link.prov_salt, 16));

	send_random();
}

static void prov_confirm(const uint8_t *data)
{
	BT_DBG("Remote Confirm: %s", bt_hex(data, 16));

	memcpy(bt_mesh_prov_link.conf, data, 16);

	notify_input_complete();

	if (!atomic_test_and_clear_bit(bt_mesh_prov_link.flags, WAIT_DH_KEY)) {
		send_confirm();
	}
}

static inline bool is_pb_gatt(void)
{
	return bt_mesh_prov_link.bearer &&
	       bt_mesh_prov_link.bearer->type == BT_MESH_PROV_GATT;
}

static void prov_data(const uint8_t *data)
{
	PROV_BUF(msg, PDU_LEN_COMPLETE);
	uint8_t session_key[16];
	uint8_t nonce[13];
	uint8_t dev_key[16];
	uint8_t pdu[25];
	uint8_t flags;
	uint32_t iv_index;
	uint16_t addr;
	uint16_t net_idx;
	int err;
	bool identity_enable;

	BT_DBG("");

	err = bt_mesh_session_key(bt_mesh_prov_link.dhkey,
				  bt_mesh_prov_link.prov_salt, session_key);
	if (err) {
		BT_ERR("Unable to generate session key");
		prov_fail(PROV_ERR_UNEXP_ERR);
		return;
	}

	BT_DBG("SessionKey: %s", bt_hex(session_key, 16));

	err = bt_mesh_prov_nonce(bt_mesh_prov_link.dhkey,
				 bt_mesh_prov_link.prov_salt, nonce);
	if (err) {
		BT_ERR("Unable to generate session nonce");
		prov_fail(PROV_ERR_UNEXP_ERR);
		return;
	}

	BT_DBG("Nonce: %s", bt_hex(nonce, 13));

	err = bt_mesh_prov_decrypt(session_key, nonce, data, pdu);
	if (err) {
		BT_ERR("Unable to decrypt provisioning data");
		prov_fail(PROV_ERR_DECRYPT);
		return;
	}

	err = bt_mesh_dev_key(bt_mesh_prov_link.dhkey,
			      bt_mesh_prov_link.prov_salt, dev_key);
	if (err) {
		BT_ERR("Unable to generate device key");
		prov_fail(PROV_ERR_UNEXP_ERR);
		return;
	}

	BT_DBG("DevKey: %s", bt_hex(dev_key, 16));

	net_idx = sys_get_be16(&pdu[16]);
	flags = pdu[18];
	iv_index = sys_get_be32(&pdu[19]);
	addr = sys_get_be16(&pdu[23]);

	BT_DBG("net_idx %u iv_index 0x%08x, addr 0x%04x",
	       net_idx, iv_index, addr);

	bt_mesh_prov_buf_init(&msg, PROV_COMPLETE);
	if (bt_mesh_prov_send(&msg, NULL)) {
		BT_ERR("Failed to send Provisioning Complete");
		return;
	}

	/* Ignore any further PDUs on this link */
	bt_mesh_prov_link.expect = PROV_NO_PDU;

	/* Store info, since bt_mesh_provision() will end up clearing it */
	if (IS_ENABLED(CONFIG_BT_MESH_GATT_PROXY)) {
		identity_enable = is_pb_gatt();
	} else {
		identity_enable = false;
	}

	err = bt_mesh_provision(pdu, net_idx, flags, iv_index, addr, dev_key);
	if (err) {
		BT_ERR("Failed to provision (err %d)", err);
		return;
	}

	/* After PB-GATT provisioning we should start advertising
	 * using Node Identity.
	 */
	if (IS_ENABLED(CONFIG_BT_MESH_GATT_PROXY) && identity_enable) {
		bt_mesh_proxy_identity_enable();
	}
}

static void local_input_complete(void)
{
	if (atomic_test_bit(bt_mesh_prov_link.flags, PUB_KEY_SENT) ||
	    atomic_test_bit(bt_mesh_prov_link.flags, OOB_PUB_KEY)) {
		send_input_complete();
	} else {
		atomic_set_bit(bt_mesh_prov_link.flags, INPUT_COMPLETE);
	}
}

static void prov_link_closed(void)
{
	reset_state();
}

static void prov_link_opened(void)
{
	bt_mesh_prov_link.expect = PROV_INVITE;
}

static const struct bt_mesh_prov_role role_device = {
	.input_complete = local_input_complete,
	.link_opened = prov_link_opened,
	.link_closed = prov_link_closed,
	.error = prov_fail,
	.op = {
		[PROV_INVITE] = prov_invite,
		[PROV_START] = prov_start,
		[PROV_PUB_KEY] = prov_pub_key,
		[PROV_CONFIRM] = prov_confirm,
		[PROV_RANDOM] = prov_random,
		[PROV_DATA] = prov_data,
	},
};

int bt_mesh_prov_enable(bt_mesh_prov_bearer_t bearers)
{
	if (bt_mesh_is_provisioned()) {
		return -EALREADY;
	}

	if (IS_ENABLED(CONFIG_BT_DEBUG)) {
		struct bt_uuid_128 uuid = { .uuid = { BT_UUID_TYPE_128 } };

		memcpy(uuid.val, bt_mesh_prov->uuid, 16);
		BT_INFO("Device UUID: %s", bt_uuid_str(&uuid.uuid));
	}

	if (IS_ENABLED(CONFIG_BT_MESH_PB_ADV) &&
	    (bearers & BT_MESH_PROV_ADV)) {
		pb_adv.link_accept(bt_mesh_prov_bearer_cb_get(), NULL);
	}

	if (IS_ENABLED(CONFIG_BT_MESH_PB_GATT) &&
	    (bearers & BT_MESH_PROV_GATT)) {
		pb_gatt.link_accept(bt_mesh_prov_bearer_cb_get(), NULL);
	}

	bt_mesh_prov_link.role = &role_device;

	return 0;
}

int bt_mesh_prov_disable(bt_mesh_prov_bearer_t bearers)
{
	if (bt_mesh_is_provisioned()) {
		return -EALREADY;
	}

	if (bt_mesh_prov_active()) {
		return -EBUSY;
	}

	if (IS_ENABLED(CONFIG_BT_MESH_PB_ADV) &&
	    (bearers & BT_MESH_PROV_ADV)) {
		bt_mesh_beacon_disable();
		bt_mesh_scan_disable();
	}

	if (IS_ENABLED(CONFIG_BT_MESH_PB_GATT) &&
	    (bearers & BT_MESH_PROV_GATT)) {
		(void)bt_mesh_pb_gatt_disable();
	}

	return 0;
}