fragattacks/src/wps/wps_common.c

/*
 * Wi-Fi Protected Setup - common functionality
 * Copyright (c) 2008, Jouni Malinen <j@w1.fi>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * Alternatively, this software may be distributed under the terms of BSD
 * license.
 *
 * See README and COPYING for more details.
 */

#include "includes.h"

#include "common.h"
#include "dh_group5.h"
#include "sha256.h"
#include "aes_wrap.h"
#include "crypto.h"
#include "wps_i.h"
#include "wps_dev_attr.h"


void wps_kdf(const u8 *key, const u8 *label_prefix, size_t label_prefix_len,
	     const char *label, u8 *res, size_t res_len)
{
	u8 i_buf[4], key_bits[4];
	const u8 *addr[4];
	size_t len[4];
	int i, iter;
	u8 hash[SHA256_MAC_LEN], *opos;
	size_t left;

	WPA_PUT_BE32(key_bits, res_len * 8);

	addr[0] = i_buf;
	len[0] = sizeof(i_buf);
	addr[1] = label_prefix;
	len[1] = label_prefix_len;
	addr[2] = (const u8 *) label;
	len[2] = os_strlen(label);
	addr[3] = key_bits;
	len[3] = sizeof(key_bits);

	iter = (res_len + SHA256_MAC_LEN - 1) / SHA256_MAC_LEN;
	opos = res;
	left = res_len;

	for (i = 1; i <= iter; i++) {
		WPA_PUT_BE32(i_buf, i);
		hmac_sha256_vector(key, SHA256_MAC_LEN, 4, addr, len, hash);
		if (i < iter) {
			os_memcpy(opos, hash, SHA256_MAC_LEN);
			opos += SHA256_MAC_LEN;
			left -= SHA256_MAC_LEN;
		} else
			os_memcpy(opos, hash, left);
	}
}


int wps_derive_keys(struct wps_data *wps)
{
	struct wpabuf *pubkey, *dh_shared;
	u8 dhkey[SHA256_MAC_LEN], kdk[SHA256_MAC_LEN];
	const u8 *addr[3];
	size_t len[3];
	u8 keys[WPS_AUTHKEY_LEN + WPS_KEYWRAPKEY_LEN + WPS_EMSK_LEN];

	if (wps->dh_privkey == NULL) {
		wpa_printf(MSG_DEBUG, "WPS: Own DH private key not available");
		return -1;
	}

	pubkey = wps->registrar ? wps->dh_pubkey_e : wps->dh_pubkey_r;
	if (pubkey == NULL) {
		wpa_printf(MSG_DEBUG, "WPS: Peer DH public key not available");
		return -1;
	}

	dh_shared = dh5_derive_shared(wps->dh_ctx, pubkey, wps->dh_privkey);
	dh5_free(wps->dh_ctx);
	wps->dh_ctx = NULL;
	dh_shared = wpabuf_zeropad(dh_shared, 192);
	if (dh_shared == NULL) {
		wpa_printf(MSG_DEBUG, "WPS: Failed to derive DH shared key");
		return -1;
	}

	/* Own DH private key is not needed anymore */
	wpabuf_free(wps->dh_privkey);
	wps->dh_privkey = NULL;

	wpa_hexdump_buf_key(MSG_DEBUG, "WPS: DH shared key", dh_shared);

	/* DHKey = SHA-256(g^AB mod p) */
	addr[0] = wpabuf_head(dh_shared);
	len[0] = wpabuf_len(dh_shared);
	sha256_vector(1, addr, len, dhkey);
	wpa_hexdump_key(MSG_DEBUG, "WPS: DHKey", dhkey, sizeof(dhkey));
	wpabuf_free(dh_shared);

	/* KDK = HMAC-SHA-256_DHKey(N1 || EnrolleeMAC || N2) */
	addr[0] = wps->nonce_e;
	len[0] = WPS_NONCE_LEN;
	addr[1] = wps->mac_addr_e;
	len[1] = ETH_ALEN;
	addr[2] = wps->nonce_r;
	len[2] = WPS_NONCE_LEN;
	hmac_sha256_vector(dhkey, sizeof(dhkey), 3, addr, len, kdk);
	wpa_hexdump_key(MSG_DEBUG, "WPS: KDK", kdk, sizeof(kdk));

	wps_kdf(kdk, NULL, 0, "Wi-Fi Easy and Secure Key Derivation",
		keys, sizeof(keys));
	os_memcpy(wps->authkey, keys, WPS_AUTHKEY_LEN);
	os_memcpy(wps->keywrapkey, keys + WPS_AUTHKEY_LEN, WPS_KEYWRAPKEY_LEN);
	os_memcpy(wps->emsk, keys + WPS_AUTHKEY_LEN + WPS_KEYWRAPKEY_LEN,
		  WPS_EMSK_LEN);

	wpa_hexdump_key(MSG_DEBUG, "WPS: AuthKey",
			wps->authkey, WPS_AUTHKEY_LEN);
	wpa_hexdump_key(MSG_DEBUG, "WPS: KeyWrapKey",
			wps->keywrapkey, WPS_KEYWRAPKEY_LEN);
	wpa_hexdump_key(MSG_DEBUG, "WPS: EMSK", wps->emsk, WPS_EMSK_LEN);

	return 0;
}


int wps_derive_mgmt_keys(struct wps_data *wps)
{
	u8 nonces[2 * WPS_NONCE_LEN];
	u8 keys[WPS_MGMTAUTHKEY_LEN + WPS_MGMTENCKEY_LEN];
	u8 hash[SHA256_MAC_LEN];
	const u8 *addr[2];
	size_t len[2];
	const char *auth_label = "WFA-WLAN-Management-MgmtAuthKey";
	const char *enc_label = "WFA-WLAN-Management-MgmtEncKey";

	/* MgmtAuthKey || MgmtEncKey =
	 * kdf(EMSK, N1 || N2 || "WFA-WLAN-Management-Keys", 384) */
	os_memcpy(nonces, wps->nonce_e, WPS_NONCE_LEN);
	os_memcpy(nonces + WPS_NONCE_LEN, wps->nonce_r, WPS_NONCE_LEN);
	wps_kdf(wps->emsk, nonces, sizeof(nonces), "WFA-WLAN-Management-Keys",
		keys, sizeof(keys));
	os_memcpy(wps->mgmt_auth_key, keys, WPS_MGMTAUTHKEY_LEN);
	os_memcpy(wps->mgmt_enc_key, keys + WPS_MGMTAUTHKEY_LEN,
		  WPS_MGMTENCKEY_LEN);

	addr[0] = nonces;
	len[0] = sizeof(nonces);

	/* MgmtEncKeyID = first 128 bits of
	 * SHA-256(N1 || N2 || "WFA-WLAN-Management-MgmtAuthKey") */
	addr[1] = (const u8 *) auth_label;
	len[1] = os_strlen(auth_label);
	sha256_vector(2, addr, len, hash);
	os_memcpy(wps->mgmt_auth_key_id, hash, WPS_MGMT_KEY_ID_LEN);

	/* MgmtEncKeyID = first 128 bits of
	 * SHA-256(N1 || N2 || "WFA-WLAN-Management-MgmtEncKey") */
	addr[1] = (const u8 *) enc_label;
	len[1] = os_strlen(enc_label);
	sha256_vector(2, addr, len, hash);
	os_memcpy(wps->mgmt_enc_key_id, hash, WPS_MGMT_KEY_ID_LEN);

	wpa_hexdump_key(MSG_DEBUG, "WPS: MgmtAuthKey",
			wps->mgmt_auth_key, WPS_MGMTAUTHKEY_LEN);
	wpa_hexdump(MSG_DEBUG, "WPS: MgmtAuthKeyID",
		    wps->mgmt_auth_key_id, WPS_MGMT_KEY_ID_LEN);
	wpa_hexdump_key(MSG_DEBUG, "WPS: MgmtEncKey",
			wps->mgmt_enc_key, WPS_MGMTENCKEY_LEN);
	wpa_hexdump(MSG_DEBUG, "WPS: MgmtEncKeyID",
		    wps->mgmt_enc_key_id, WPS_MGMT_KEY_ID_LEN);

	return 0;
}


void wps_derive_psk(struct wps_data *wps, const u8 *dev_passwd,
		    size_t dev_passwd_len)
{
	u8 hash[SHA256_MAC_LEN];

	hmac_sha256(wps->authkey, WPS_AUTHKEY_LEN, dev_passwd,
		    (dev_passwd_len + 1) / 2, hash);
	os_memcpy(wps->psk1, hash, WPS_PSK_LEN);
	hmac_sha256(wps->authkey, WPS_AUTHKEY_LEN,
		    dev_passwd + (dev_passwd_len + 1) / 2,
		    dev_passwd_len / 2, hash);
	os_memcpy(wps->psk2, hash, WPS_PSK_LEN);

	wpa_hexdump_ascii_key(MSG_DEBUG, "WPS: Device Password",
			      dev_passwd, dev_passwd_len);
	wpa_hexdump_key(MSG_DEBUG, "WPS: PSK1", wps->psk1, WPS_PSK_LEN);
	wpa_hexdump_key(MSG_DEBUG, "WPS: PSK2", wps->psk2, WPS_PSK_LEN);
}


struct wpabuf * wps_decrypt_encr_settings(struct wps_data *wps, const u8 *encr,
					  size_t encr_len)
{
	struct wpabuf *decrypted;
	const size_t block_size = 16;
	size_t i;
	u8 pad;
	const u8 *pos;

	/* AES-128-CBC */
	if (encr == NULL || encr_len < 2 * block_size || encr_len % block_size)
	{
		wpa_printf(MSG_DEBUG, "WPS: No Encrypted Settings received");
		return NULL;
	}

	decrypted = wpabuf_alloc(encr_len - block_size);
	if (decrypted == NULL)
		return NULL;

	wpa_hexdump(MSG_MSGDUMP, "WPS: Encrypted Settings", encr, encr_len);
	wpabuf_put_data(decrypted, encr + block_size, encr_len - block_size);
	if (aes_128_cbc_decrypt(wps->keywrapkey, encr, wpabuf_mhead(decrypted),
				wpabuf_len(decrypted))) {
		wpabuf_free(decrypted);
		return NULL;
	}

	wpa_hexdump_buf_key(MSG_MSGDUMP, "WPS: Decrypted Encrypted Settings",
			    decrypted);

	pos = wpabuf_head_u8(decrypted) + wpabuf_len(decrypted) - 1;
	pad = *pos;
	if (pad > wpabuf_len(decrypted)) {
		wpa_printf(MSG_DEBUG, "WPS: Invalid PKCS#5 v2.0 pad value");
		wpabuf_free(decrypted);
		return NULL;
	}
	for (i = 0; i < pad; i++) {
		if (*pos-- != pad) {
			wpa_printf(MSG_DEBUG, "WPS: Invalid PKCS#5 v2.0 pad "
				   "string");
			wpabuf_free(decrypted);
			return NULL;
		}
	}
	decrypted->used -= pad;

	return decrypted;
}


/**
 * wps_pin_checksum - Compute PIN checksum
 * @pin: Seven digit PIN (i.e., eight digit PIN without the checksum digit)
 * Returns: Checksum digit
 */
unsigned int wps_pin_checksum(unsigned int pin)
{
	unsigned int accum = 0;
	while (pin) {
		accum += 3 * (pin % 10);
		pin /= 10;
		accum += pin % 10;
		pin /= 10;
	}

	return (10 - accum % 10) % 10;
}


/**
 * wps_pin_valid - Check whether a PIN has a valid checksum
 * @pin: Eight digit PIN (i.e., including the checksum digit)
 * Returns: 1 if checksum digit is valid, or 0 if not
 */
unsigned int wps_pin_valid(unsigned int pin)
{
	return wps_pin_checksum(pin / 10) == (pin % 10);
}


/**
 * wps_generate_pin - Generate a random PIN
 * Returns: Eight digit PIN (i.e., including the checksum digit)
 */
unsigned int wps_generate_pin(void)
{
	unsigned int val;

	/* Generate seven random digits for the PIN */
	if (os_get_random((unsigned char *) &val, sizeof(val)) < 0) {
		struct os_time now;
		os_get_time(&now);
		val = os_random() ^ now.sec ^ now.usec;
	}
	val %= 10000000;

	/* Append checksum digit */
	return val * 10 + wps_pin_checksum(val);
}


void wps_fail_event(struct wps_context *wps, enum wps_msg_type msg)
{
	union wps_event_data data;

	if (wps->event_cb == NULL)
		return;

	os_memset(&data, 0, sizeof(data));
	data.fail.msg = msg;
	wps->event_cb(wps->cb_ctx, WPS_EV_FAIL, &data);
}


void wps_success_event(struct wps_context *wps)
{
	if (wps->event_cb == NULL)
		return;

	wps->event_cb(wps->cb_ctx, WPS_EV_SUCCESS, NULL);
}


void wps_pwd_auth_fail_event(struct wps_context *wps, int enrollee, int part)
{
	union wps_event_data data;

	if (wps->event_cb == NULL)
		return;

	os_memset(&data, 0, sizeof(data));
	data.pwd_auth_fail.enrollee = enrollee;
	data.pwd_auth_fail.part = part;
	wps->event_cb(wps->cb_ctx, WPS_EV_PWD_AUTH_FAIL, &data);
}


#ifdef CONFIG_WPS_OOB

static struct wpabuf * wps_get_oob_cred(struct wps_context *wps)
{
	struct wps_data data;
	struct wpabuf *plain;

	plain = wpabuf_alloc(500);
	if (plain == NULL) {
		wpa_printf(MSG_ERROR, "WPS: Failed to allocate memory for OOB "
			   "credential");
		return NULL;
	}

	os_memset(&data, 0, sizeof(data));
	data.wps = wps;
	data.auth_type = wps->auth_types;
	data.encr_type = wps->encr_types;
	if (wps_build_version(plain) || wps_build_cred(&data, plain)) {
		wpabuf_free(plain);
		return NULL;
	}

	return plain;
}


static struct wpabuf * wps_get_oob_dev_pwd(struct wps_context *wps)
{
	struct wpabuf *data;

	data = wpabuf_alloc(9 + WPS_OOB_DEVICE_PASSWORD_ATTR_LEN);
	if (data == NULL) {
		wpa_printf(MSG_ERROR, "WPS: Failed to allocate memory for OOB "
			   "device password attribute");
		return NULL;
	}

	wpabuf_free(wps->oob_conf.dev_password);
	wps->oob_conf.dev_password =
		wpabuf_alloc(WPS_OOB_DEVICE_PASSWORD_LEN * 2 + 1);
	if (wps->oob_conf.dev_password == NULL) {
		wpa_printf(MSG_ERROR, "WPS: Failed to allocate memory for OOB "
			   "device password");
		wpabuf_free(data);
		return NULL;
	}

	if (wps_build_version(data) ||
	    wps_build_oob_dev_password(data, wps)) {
		wpa_printf(MSG_ERROR, "WPS: Build OOB device password "
			   "attribute error");
		wpabuf_free(data);
		return NULL;
	}

	return data;
}


static int wps_parse_oob_dev_pwd(struct wps_context *wps,
				 struct wpabuf *data)
{
	struct oob_conf_data *oob_conf = &wps->oob_conf;
	struct wps_parse_attr attr;
	const u8 *pos;

	if (wps_parse_msg(data, &attr) < 0 ||
	    attr.oob_dev_password == NULL) {
		wpa_printf(MSG_ERROR, "WPS: OOB device password not found");
		return -1;
	}

	pos = attr.oob_dev_password;

	oob_conf->pubkey_hash =
		wpabuf_alloc_copy(pos, WPS_OOB_PUBKEY_HASH_LEN);
	if (oob_conf->pubkey_hash == NULL) {
		wpa_printf(MSG_ERROR, "WPS: Failed to allocate memory for OOB "
			   "public key hash");
		return -1;
	}
	pos += WPS_OOB_PUBKEY_HASH_LEN;

	wps->oob_dev_pw_id = WPA_GET_BE16(pos);
	pos += sizeof(wps->oob_dev_pw_id);

	oob_conf->dev_password =
		wpabuf_alloc(WPS_OOB_DEVICE_PASSWORD_LEN * 2 + 1);
	if (oob_conf->dev_password == NULL) {
		wpa_printf(MSG_ERROR, "WPS: Failed to allocate memory for OOB "
			   "device password");
		return -1;
	}
	wpa_snprintf_hex_uppercase(wpabuf_put(oob_conf->dev_password,
				   wpabuf_size(oob_conf->dev_password)),
				   wpabuf_size(oob_conf->dev_password), pos,
				   WPS_OOB_DEVICE_PASSWORD_LEN);

	return 0;
}


static int wps_parse_oob_cred(struct wps_context *wps, struct wpabuf *data)
{
	struct wpabuf msg;
	struct wps_parse_attr attr;
	size_t i;

	if (wps_parse_msg(data, &attr) < 0 || attr.num_cred <= 0) {
		wpa_printf(MSG_ERROR, "WPS: OOB credential not found");
		return -1;
	}

	for (i = 0; i < attr.num_cred; i++) {
		struct wps_credential local_cred;
		struct wps_parse_attr cattr;

		os_memset(&local_cred, 0, sizeof(local_cred));
		wpabuf_set(&msg, attr.cred[i], attr.cred_len[i]);
		if (wps_parse_msg(&msg, &cattr) < 0 ||
		    wps_process_cred(&cattr, &local_cred)) {
			wpa_printf(MSG_ERROR, "WPS: Failed to parse OOB "
				   "credential");
			return -1;
		}
		wps->cred_cb(wps->cb_ctx, &local_cred);
	}

	return 0;
}


int wps_process_oob(struct wps_context *wps, struct oob_device_data *oob_dev,
		    int registrar)
{
	struct wpabuf *data;
	int ret, write_f, oob_method = wps->oob_conf.oob_method;
	void *oob_priv;

	write_f = oob_method == OOB_METHOD_DEV_PWD_E ? !registrar : registrar;

	oob_priv = oob_dev->init_func(wps, oob_dev, registrar);
	if (oob_priv == NULL) {
		wpa_printf(MSG_ERROR, "WPS: Failed to initialize OOB device");
		return -1;
	}

	if (write_f) {
		if (oob_method == OOB_METHOD_CRED)
			data = wps_get_oob_cred(wps);
		else
			data = wps_get_oob_dev_pwd(wps);

		ret = 0;
		if (data == NULL || oob_dev->write_func(oob_priv, data) < 0)
			ret = -1;
	} else {
		data = oob_dev->read_func(oob_priv);
		if (data == NULL)
			ret = -1;
		else {
			if (oob_method == OOB_METHOD_CRED)
				ret = wps_parse_oob_cred(wps, data);
			else
				ret = wps_parse_oob_dev_pwd(wps, data);
		}
	}
	wpabuf_free(data);
	oob_dev->deinit_func(oob_priv);

	if (ret < 0) {
		wpa_printf(MSG_ERROR, "WPS: Failed to process OOB data");
		return -1;
	}

	return 0;
}


struct oob_device_data * wps_get_oob_device(char *device_type)
{
#ifdef CONFIG_WPS_UFD
	if (os_strstr(device_type, "ufd") != NULL)
		return &oob_ufd_device_data;
#endif /* CONFIG_WPS_UFD */
#ifdef CONFIG_WPS_NFC
	if (os_strstr(device_type, "nfc") != NULL)
		return &oob_nfc_device_data;
#endif /* CONFIG_WPS_NFC */

	return NULL;
}


#ifdef CONFIG_WPS_NFC
struct oob_nfc_device_data * wps_get_oob_nfc_device(char *device_name)
{
	if (device_name == NULL)
		return NULL;
#ifdef CONFIG_WPS_NFC_PN531
	if (os_strstr(device_name, "pn531") != NULL)
		return &oob_nfc_pn531_device_data;
#endif /* CONFIG_WPS_NFC_PN531 */

	return NULL;
}
#endif /* CONFIG_WPS_NFC */


int wps_get_oob_method(char *method)
{
	if (os_strstr(method, "pin-e") != NULL)
		return OOB_METHOD_DEV_PWD_E;
	if (os_strstr(method, "pin-r") != NULL)
		return OOB_METHOD_DEV_PWD_R;
	if (os_strstr(method, "cred") != NULL)
		return OOB_METHOD_CRED;
	return OOB_METHOD_UNKNOWN;
}

#endif /* CONFIG_WPS_OOB */