wps_common.c

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#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;
}


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;
}


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;
}


unsigned int wps_pin_valid(unsigned int pin)
{
        return wps_pin_checksum(pin / 10) == (pin % 10);
}


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);
}


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

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


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

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


#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 */