wps_attr_process.c

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/*
 * Wi-Fi Protected Setup - attribute processing
 * 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 "crypto/sha256.h"
#include "wps_i.h"


int wps_process_authenticator(struct wps_data *wps, const u8 *authenticator,
                              const struct wpabuf *msg)
{
        u8 hash[SHA256_MAC_LEN];
        const u8 *addr[2];
        size_t len[2];

        if (authenticator == NULL) {
                wpa_printf(MSG_DEBUG, "WPS: No Authenticator attribute "
                           "included");
                return -1;
        }

        if (wps->last_msg == NULL) {
                wpa_printf(MSG_DEBUG, "WPS: Last message not available for "
                           "validating authenticator");
                return -1;
        }

        /* Authenticator = HMAC-SHA256_AuthKey(M_prev || M_curr*)
         * (M_curr* is M_curr without the Authenticator attribute)
         */
        addr[0] = wpabuf_head(wps->last_msg);
        len[0] = wpabuf_len(wps->last_msg);
        addr[1] = wpabuf_head(msg);
        len[1] = wpabuf_len(msg) - 4 - WPS_AUTHENTICATOR_LEN;
        hmac_sha256_vector(wps->authkey, WPS_AUTHKEY_LEN, 2, addr, len, hash);

        if (os_memcmp(hash, authenticator, WPS_AUTHENTICATOR_LEN) != 0) {
                wpa_printf(MSG_DEBUG, "WPS: Incorrect Authenticator");
                return -1;
        }

        return 0;
}


int wps_process_key_wrap_auth(struct wps_data *wps, struct wpabuf *msg,
                              const u8 *key_wrap_auth)
{
        u8 hash[SHA256_MAC_LEN];
        const u8 *head;
        size_t len;

        if (key_wrap_auth == NULL) {
                wpa_printf(MSG_DEBUG, "WPS: No KWA in decrypted attribute");
                return -1;
        }

        head = wpabuf_head(msg);
        len = wpabuf_len(msg) - 4 - WPS_KWA_LEN;
        if (head + len != key_wrap_auth - 4) {
                wpa_printf(MSG_DEBUG, "WPS: KWA not in the end of the "
                           "decrypted attribute");
                return -1;
        }

        hmac_sha256(wps->authkey, WPS_AUTHKEY_LEN, head, len, hash);
        if (os_memcmp(hash, key_wrap_auth, WPS_KWA_LEN) != 0) {
                wpa_printf(MSG_DEBUG, "WPS: Invalid KWA");
                return -1;
        }

        return 0;
}


static int wps_process_cred_network_idx(struct wps_credential *cred,
                                        const u8 *idx)
{
        if (idx == NULL) {
                wpa_printf(MSG_DEBUG, "WPS: Credential did not include "
                           "Network Index");
                return -1;
        }

        wpa_printf(MSG_DEBUG, "WPS: Network Index: %d", *idx);

        return 0;
}


static int wps_process_cred_ssid(struct wps_credential *cred, const u8 *ssid,
                                 size_t ssid_len)
{
        if (ssid == NULL) {
                wpa_printf(MSG_DEBUG, "WPS: Credential did not include SSID");
                return -1;
        }

        /* Remove zero-padding since some Registrar implementations seem to use
         * hardcoded 32-octet length for this attribute */
        while (ssid_len > 0 && ssid[ssid_len - 1] == 0)
                ssid_len--;

        wpa_hexdump_ascii(MSG_DEBUG, "WPS: SSID", ssid, ssid_len);
        if (ssid_len <= sizeof(cred->ssid)) {
                os_memcpy(cred->ssid, ssid, ssid_len);
                cred->ssid_len = ssid_len;
        }

        return 0;
}


static int wps_process_cred_auth_type(struct wps_credential *cred,
                                      const u8 *auth_type)
{
        if (auth_type == NULL) {
                wpa_printf(MSG_DEBUG, "WPS: Credential did not include "
                           "Authentication Type");
                return -1;
        }

        cred->auth_type = WPA_GET_BE16(auth_type);
        wpa_printf(MSG_DEBUG, "WPS: Authentication Type: 0x%x",
                   cred->auth_type);

        return 0;
}


static int wps_process_cred_encr_type(struct wps_credential *cred,
                                      const u8 *encr_type)
{
        if (encr_type == NULL) {
                wpa_printf(MSG_DEBUG, "WPS: Credential did not include "
                           "Encryption Type");
                return -1;
        }

        cred->encr_type = WPA_GET_BE16(encr_type);
        wpa_printf(MSG_DEBUG, "WPS: Encryption Type: 0x%x",
                   cred->encr_type);

        return 0;
}


static int wps_process_cred_network_key_idx(struct wps_credential *cred,
                                            const u8 *key_idx)
{
        if (key_idx == NULL)
                return 0; /* optional attribute */

        wpa_printf(MSG_DEBUG, "WPS: Network Key Index: %d", *key_idx);
        cred->key_idx = *key_idx;

        return 0;
}


static int wps_process_cred_network_key(struct wps_credential *cred,
                                        const u8 *key, size_t key_len)
{
        if (key == NULL) {
                wpa_printf(MSG_DEBUG, "WPS: Credential did not include "
                           "Network Key");
                return -1;
        }

        wpa_hexdump_key(MSG_DEBUG, "WPS: Network Key", key, key_len);
        if (key_len <= sizeof(cred->key)) {
                os_memcpy(cred->key, key, key_len);
                cred->key_len = key_len;
        }

        return 0;
}


static int wps_process_cred_mac_addr(struct wps_credential *cred,
                                     const u8 *mac_addr)
{
        if (mac_addr == NULL) {
                wpa_printf(MSG_DEBUG, "WPS: Credential did not include "
                           "MAC Address");
                return -1;
        }

        wpa_printf(MSG_DEBUG, "WPS: MAC Address " MACSTR, MAC2STR(mac_addr));
        os_memcpy(cred->mac_addr, mac_addr, ETH_ALEN);

        return 0;
}


static int wps_process_cred_eap_type(struct wps_credential *cred,
                                     const u8 *eap_type, size_t eap_type_len)
{
        if (eap_type == NULL)
                return 0; /* optional attribute */

        wpa_hexdump(MSG_DEBUG, "WPS: EAP Type", eap_type, eap_type_len);

        return 0;
}


static int wps_process_cred_eap_identity(struct wps_credential *cred,
                                         const u8 *identity,
                                         size_t identity_len)
{
        if (identity == NULL)
                return 0; /* optional attribute */

        wpa_hexdump_ascii(MSG_DEBUG, "WPS: EAP Identity",
                          identity, identity_len);

        return 0;
}


static int wps_process_cred_key_prov_auto(struct wps_credential *cred,
                                          const u8 *key_prov_auto)
{
        if (key_prov_auto == NULL)
                return 0; /* optional attribute */

        wpa_printf(MSG_DEBUG, "WPS: Key Provided Automatically: %d",
                   *key_prov_auto);

        return 0;
}


static int wps_process_cred_802_1x_enabled(struct wps_credential *cred,
                                           const u8 *dot1x_enabled)
{
        if (dot1x_enabled == NULL)
                return 0; /* optional attribute */

        wpa_printf(MSG_DEBUG, "WPS: 802.1X Enabled: %d", *dot1x_enabled);

        return 0;
}


static void wps_workaround_cred_key(struct wps_credential *cred)
{
        if (cred->auth_type & (WPS_AUTH_WPAPSK | WPS_AUTH_WPA2PSK) &&
            cred->key_len > 8 && cred->key_len < 64 &&
            cred->key[cred->key_len - 1] == 0) {
                /*
                 * A deployed external registrar is known to encode ASCII
                 * passphrases incorrectly. Remove the extra NULL termination
                 * to fix the encoding.
                 */
                wpa_printf(MSG_DEBUG, "WPS: Workaround - remove NULL "
                           "termination from ASCII passphrase");
                cred->key_len--;
        }
}


int wps_process_cred(struct wps_parse_attr *attr,
                     struct wps_credential *cred)
{
        wpa_printf(MSG_DEBUG, "WPS: Process Credential");

        /* TODO: support multiple Network Keys */
        if (wps_process_cred_network_idx(cred, attr->network_idx) ||
            wps_process_cred_ssid(cred, attr->ssid, attr->ssid_len) ||
            wps_process_cred_auth_type(cred, attr->auth_type) ||
            wps_process_cred_encr_type(cred, attr->encr_type) ||
            wps_process_cred_network_key_idx(cred, attr->network_key_idx) ||
            wps_process_cred_network_key(cred, attr->network_key,
                                         attr->network_key_len) ||
            wps_process_cred_mac_addr(cred, attr->mac_addr) ||
            wps_process_cred_eap_type(cred, attr->eap_type,
                                      attr->eap_type_len) ||
            wps_process_cred_eap_identity(cred, attr->eap_identity,
                                          attr->eap_identity_len) ||
            wps_process_cred_key_prov_auto(cred, attr->key_prov_auto) ||
            wps_process_cred_802_1x_enabled(cred, attr->dot1x_enabled))
                return -1;

        wps_workaround_cred_key(cred);

        return 0;
}


int wps_process_ap_settings(struct wps_parse_attr *attr,
                            struct wps_credential *cred)
{
        wpa_printf(MSG_DEBUG, "WPS: Processing AP Settings");
        os_memset(cred, 0, sizeof(*cred));
        /* TODO: optional attributes New Password and Device Password ID */
        if (wps_process_cred_ssid(cred, attr->ssid, attr->ssid_len) ||
            wps_process_cred_auth_type(cred, attr->auth_type) ||
            wps_process_cred_encr_type(cred, attr->encr_type) ||
            wps_process_cred_network_key_idx(cred, attr->network_key_idx) ||
            wps_process_cred_network_key(cred, attr->network_key,
                                         attr->network_key_len) ||
            wps_process_cred_mac_addr(cred, attr->mac_addr))
                return -1;

        wps_workaround_cred_key(cred);

        return 0;
}