eap_server_aka.c

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/*
 * hostapd / EAP-AKA (RFC 4187) and EAP-AKA' (draft-arkko-eap-aka-kdf)
 * Copyright (c) 2005-2008, 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 "crypto/crypto.h"
#include "eap_common/eap_sim_common.h"
#include "eap_server/eap_i.h"
#include "eap_server/eap_sim_db.h"


struct eap_aka_data {
        u8 mk[EAP_SIM_MK_LEN];
        u8 nonce_s[EAP_SIM_NONCE_S_LEN];
        u8 k_aut[EAP_AKA_PRIME_K_AUT_LEN];
        u8 k_encr[EAP_SIM_K_ENCR_LEN];
        u8 k_re[EAP_AKA_PRIME_K_RE_LEN]; /* EAP-AKA' only */
        u8 msk[EAP_SIM_KEYING_DATA_LEN];
        u8 emsk[EAP_EMSK_LEN];
        u8 rand[EAP_AKA_RAND_LEN];
        u8 autn[EAP_AKA_AUTN_LEN];
        u8 ck[EAP_AKA_CK_LEN];
        u8 ik[EAP_AKA_IK_LEN];
        u8 res[EAP_AKA_RES_MAX_LEN];
        size_t res_len;
        enum {
                IDENTITY, CHALLENGE, REAUTH, NOTIFICATION, SUCCESS, FAILURE
        } state;
        char *next_pseudonym;
        char *next_reauth_id;
        u16 counter;
        struct eap_sim_reauth *reauth;
        int auts_reported; /* whether the current AUTS has been reported to the
                            * eap_sim_db */
        u16 notification;
        int use_result_ind;

        struct wpabuf *id_msgs;
        int pending_id;
        u8 eap_method;
        u8 *network_name;
        size_t network_name_len;
        u16 kdf;
};


static void eap_aka_determine_identity(struct eap_sm *sm,
                                       struct eap_aka_data *data,
                                       int before_identity, int after_reauth);


static const char * eap_aka_state_txt(int state)
{
        switch (state) {
        case IDENTITY:
                return "IDENTITY";
        case CHALLENGE:
                return "CHALLENGE";
        case REAUTH:
                return "REAUTH";
        case SUCCESS:
                return "SUCCESS";
        case FAILURE:
                return "FAILURE";
        case NOTIFICATION:
                return "NOTIFICATION";
        default:
                return "Unknown?!";
        }
}


static void eap_aka_state(struct eap_aka_data *data, int state)
{
        wpa_printf(MSG_DEBUG, "EAP-AKA: %s -> %s",
                   eap_aka_state_txt(data->state),
                   eap_aka_state_txt(state));
        data->state = state;
}


static void * eap_aka_init(struct eap_sm *sm)
{
        struct eap_aka_data *data;

        if (sm->eap_sim_db_priv == NULL) {
                wpa_printf(MSG_WARNING, "EAP-AKA: eap_sim_db not configured");
                return NULL;
        }

        data = os_zalloc(sizeof(*data));
        if (data == NULL)
                return NULL;

        data->eap_method = EAP_TYPE_AKA;

        data->state = IDENTITY;
        eap_aka_determine_identity(sm, data, 1, 0);
        data->pending_id = -1;

        return data;
}


#ifdef EAP_SERVER_AKA_PRIME
static void * eap_aka_prime_init(struct eap_sm *sm)
{
        struct eap_aka_data *data;
        /* TODO: make ANID configurable; see 3GPP TS 24.302 */
        char *network_name = "WLAN";

        if (sm->eap_sim_db_priv == NULL) {
                wpa_printf(MSG_WARNING, "EAP-AKA: eap_sim_db not configured");
                return NULL;
        }

        data = os_zalloc(sizeof(*data));
        if (data == NULL)
                return NULL;

        data->eap_method = EAP_TYPE_AKA_PRIME;
        data->network_name = os_malloc(os_strlen(network_name));
        if (data->network_name == NULL) {
                os_free(data);
                return NULL;
        }

        data->network_name_len = os_strlen(network_name);
        os_memcpy(data->network_name, network_name, data->network_name_len);

        data->state = IDENTITY;
        eap_aka_determine_identity(sm, data, 1, 0);
        data->pending_id = -1;

        return data;
}
#endif /* EAP_SERVER_AKA_PRIME */


static void eap_aka_reset(struct eap_sm *sm, void *priv)
{
        struct eap_aka_data *data = priv;
        os_free(data->next_pseudonym);
        os_free(data->next_reauth_id);
        wpabuf_free(data->id_msgs);
        os_free(data->network_name);
        os_free(data);
}


static int eap_aka_add_id_msg(struct eap_aka_data *data,
                              const struct wpabuf *msg)
{
        if (msg == NULL)
                return -1;

        if (data->id_msgs == NULL) {
                data->id_msgs = wpabuf_dup(msg);
                return data->id_msgs == NULL ? -1 : 0;
        }

        if (wpabuf_resize(&data->id_msgs, wpabuf_len(msg)) < 0)
                return -1;
        wpabuf_put_buf(data->id_msgs, msg);

        return 0;
}


static void eap_aka_add_checkcode(struct eap_aka_data *data,
                                  struct eap_sim_msg *msg)
{
        const u8 *addr;
        size_t len;
        u8 hash[SHA256_MAC_LEN];

        wpa_printf(MSG_DEBUG, "   AT_CHECKCODE");

        if (data->id_msgs == NULL) {
                /*
                 * No EAP-AKA/Identity packets were exchanged - send empty
                 * checkcode.
                 */
                eap_sim_msg_add(msg, EAP_SIM_AT_CHECKCODE, 0, NULL, 0);
                return;
        }

        /* Checkcode is SHA1 hash over all EAP-AKA/Identity packets. */
        addr = wpabuf_head(data->id_msgs);
        len = wpabuf_len(data->id_msgs);
        wpa_hexdump(MSG_MSGDUMP, "EAP-AKA: AT_CHECKCODE data", addr, len);
        if (data->eap_method == EAP_TYPE_AKA_PRIME)
                sha256_vector(1, &addr, &len, hash);
        else
                sha1_vector(1, &addr, &len, hash);

        eap_sim_msg_add(msg, EAP_SIM_AT_CHECKCODE, 0, hash,
                        data->eap_method == EAP_TYPE_AKA_PRIME ?
                        EAP_AKA_PRIME_CHECKCODE_LEN : EAP_AKA_CHECKCODE_LEN);
}


static int eap_aka_verify_checkcode(struct eap_aka_data *data,
                                    const u8 *checkcode, size_t checkcode_len)
{
        const u8 *addr;
        size_t len;
        u8 hash[SHA256_MAC_LEN];
        size_t hash_len;

        if (checkcode == NULL)
                return -1;

        if (data->id_msgs == NULL) {
                if (checkcode_len != 0) {
                        wpa_printf(MSG_DEBUG, "EAP-AKA: Checkcode from peer "
                                   "indicates that AKA/Identity messages were "
                                   "used, but they were not");
                        return -1;
                }
                return 0;
        }

        hash_len = data->eap_method == EAP_TYPE_AKA_PRIME ?
                EAP_AKA_PRIME_CHECKCODE_LEN : EAP_AKA_CHECKCODE_LEN;

        if (checkcode_len != hash_len) {
                wpa_printf(MSG_DEBUG, "EAP-AKA: Checkcode from peer indicates "
                           "that AKA/Identity message were not used, but they "
                           "were");
                return -1;
        }

        /* Checkcode is SHA1 hash over all EAP-AKA/Identity packets. */
        addr = wpabuf_head(data->id_msgs);
        len = wpabuf_len(data->id_msgs);
        if (data->eap_method == EAP_TYPE_AKA_PRIME)
                sha256_vector(1, &addr, &len, hash);
        else
                sha1_vector(1, &addr, &len, hash);

        if (os_memcmp(hash, checkcode, hash_len) != 0) {
                wpa_printf(MSG_DEBUG, "EAP-AKA: Mismatch in AT_CHECKCODE");
                return -1;
        }

        return 0;
}


static struct wpabuf * eap_aka_build_identity(struct eap_sm *sm,
                                              struct eap_aka_data *data, u8 id)
{
        struct eap_sim_msg *msg;
        struct wpabuf *buf;

        wpa_printf(MSG_DEBUG, "EAP-AKA: Generating Identity");
        msg = eap_sim_msg_init(EAP_CODE_REQUEST, id, data->eap_method,
                               EAP_AKA_SUBTYPE_IDENTITY);
        if (eap_sim_db_identity_known(sm->eap_sim_db_priv, sm->identity,
                                      sm->identity_len)) {
                wpa_printf(MSG_DEBUG, "   AT_PERMANENT_ID_REQ");
                eap_sim_msg_add(msg, EAP_SIM_AT_PERMANENT_ID_REQ, 0, NULL, 0);
        } else {
                /*
                 * RFC 4187, Chap. 4.1.4 recommends that identity from EAP is
                 * ignored and the AKA/Identity is used to request the
                 * identity.
                 */
                wpa_printf(MSG_DEBUG, "   AT_ANY_ID_REQ");
                eap_sim_msg_add(msg, EAP_SIM_AT_ANY_ID_REQ, 0, NULL, 0);
        }
        buf = eap_sim_msg_finish(msg, NULL, NULL, 0);
        if (eap_aka_add_id_msg(data, buf) < 0) {
                wpabuf_free(buf);
                return NULL;
        }
        data->pending_id = id;
        return buf;
}


static int eap_aka_build_encr(struct eap_sm *sm, struct eap_aka_data *data,
                              struct eap_sim_msg *msg, u16 counter,
                              const u8 *nonce_s)
{
        os_free(data->next_pseudonym);
        data->next_pseudonym =
                eap_sim_db_get_next_pseudonym(sm->eap_sim_db_priv, 1);
        os_free(data->next_reauth_id);
        if (data->counter <= EAP_AKA_MAX_FAST_REAUTHS) {
                data->next_reauth_id =
                        eap_sim_db_get_next_reauth_id(sm->eap_sim_db_priv, 1);
        } else {
                wpa_printf(MSG_DEBUG, "EAP-AKA: Max fast re-authentication "
                           "count exceeded - force full authentication");
                data->next_reauth_id = NULL;
        }

        if (data->next_pseudonym == NULL && data->next_reauth_id == NULL &&
            counter == 0 && nonce_s == NULL)
                return 0;

        wpa_printf(MSG_DEBUG, "   AT_IV");
        wpa_printf(MSG_DEBUG, "   AT_ENCR_DATA");
        eap_sim_msg_add_encr_start(msg, EAP_SIM_AT_IV, EAP_SIM_AT_ENCR_DATA);

        if (counter > 0) {
                wpa_printf(MSG_DEBUG, "   *AT_COUNTER (%u)", counter);
                eap_sim_msg_add(msg, EAP_SIM_AT_COUNTER, counter, NULL, 0);
        }

        if (nonce_s) {
                wpa_printf(MSG_DEBUG, "   *AT_NONCE_S");
                eap_sim_msg_add(msg, EAP_SIM_AT_NONCE_S, 0, nonce_s,
                                EAP_SIM_NONCE_S_LEN);
        }

        if (data->next_pseudonym) {
                wpa_printf(MSG_DEBUG, "   *AT_NEXT_PSEUDONYM (%s)",
                           data->next_pseudonym);
                eap_sim_msg_add(msg, EAP_SIM_AT_NEXT_PSEUDONYM,
                                os_strlen(data->next_pseudonym),
                                (u8 *) data->next_pseudonym,
                                os_strlen(data->next_pseudonym));
        }

        if (data->next_reauth_id) {
                wpa_printf(MSG_DEBUG, "   *AT_NEXT_REAUTH_ID (%s)",
                           data->next_reauth_id);
                eap_sim_msg_add(msg, EAP_SIM_AT_NEXT_REAUTH_ID,
                                os_strlen(data->next_reauth_id),
                                (u8 *) data->next_reauth_id,
                                os_strlen(data->next_reauth_id));
        }

        if (eap_sim_msg_add_encr_end(msg, data->k_encr, EAP_SIM_AT_PADDING)) {
                wpa_printf(MSG_WARNING, "EAP-AKA: Failed to encrypt "
                           "AT_ENCR_DATA");
                return -1;
        }

        return 0;
}


static struct wpabuf * eap_aka_build_challenge(struct eap_sm *sm,
                                               struct eap_aka_data *data,
                                               u8 id)
{
        struct eap_sim_msg *msg;

        wpa_printf(MSG_DEBUG, "EAP-AKA: Generating Challenge");
        msg = eap_sim_msg_init(EAP_CODE_REQUEST, id, data->eap_method,
                               EAP_AKA_SUBTYPE_CHALLENGE);
        wpa_printf(MSG_DEBUG, "   AT_RAND");
        eap_sim_msg_add(msg, EAP_SIM_AT_RAND, 0, data->rand, EAP_AKA_RAND_LEN);
        wpa_printf(MSG_DEBUG, "   AT_AUTN");
        eap_sim_msg_add(msg, EAP_SIM_AT_AUTN, 0, data->autn, EAP_AKA_AUTN_LEN);
        if (data->eap_method == EAP_TYPE_AKA_PRIME) {
                if (data->kdf) {
                        /* Add the selected KDF into the beginning */
                        wpa_printf(MSG_DEBUG, "   AT_KDF");
                        eap_sim_msg_add(msg, EAP_SIM_AT_KDF, data->kdf,
                                        NULL, 0);
                }
                wpa_printf(MSG_DEBUG, "   AT_KDF");
                eap_sim_msg_add(msg, EAP_SIM_AT_KDF, EAP_AKA_PRIME_KDF,
                                NULL, 0);
                wpa_printf(MSG_DEBUG, "   AT_KDF_INPUT");
                eap_sim_msg_add(msg, EAP_SIM_AT_KDF_INPUT,
                                data->network_name_len,
                                data->network_name, data->network_name_len);
        }

        if (eap_aka_build_encr(sm, data, msg, 0, NULL)) {
                eap_sim_msg_free(msg);
                return NULL;
        }

        eap_aka_add_checkcode(data, msg);

        if (sm->eap_sim_aka_result_ind) {
                wpa_printf(MSG_DEBUG, "   AT_RESULT_IND");
                eap_sim_msg_add(msg, EAP_SIM_AT_RESULT_IND, 0, NULL, 0);
        }

#ifdef EAP_SERVER_AKA_PRIME
        if (data->eap_method == EAP_TYPE_AKA) {
                u16 flags = 0;
                int i;
                int aka_prime_preferred = 0;

                i = 0;
                while (sm->user && i < EAP_MAX_METHODS &&
                       (sm->user->methods[i].vendor != EAP_VENDOR_IETF ||
                        sm->user->methods[i].method != EAP_TYPE_NONE)) {
                        if (sm->user->methods[i].vendor == EAP_VENDOR_IETF) {
                                if (sm->user->methods[i].method ==
                                    EAP_TYPE_AKA)
                                        break;
                                if (sm->user->methods[i].method ==
                                    EAP_TYPE_AKA_PRIME) {
                                        aka_prime_preferred = 1;
                                        break;
                                }
                        }
                        i++;
                }

                if (aka_prime_preferred)
                        flags |= EAP_AKA_BIDDING_FLAG_D;
                eap_sim_msg_add(msg, EAP_SIM_AT_BIDDING, flags, NULL, 0);
        }
#endif /* EAP_SERVER_AKA_PRIME */

        wpa_printf(MSG_DEBUG, "   AT_MAC");
        eap_sim_msg_add_mac(msg, EAP_SIM_AT_MAC);
        return eap_sim_msg_finish(msg, data->k_aut, NULL, 0);
}


static struct wpabuf * eap_aka_build_reauth(struct eap_sm *sm,
                                            struct eap_aka_data *data, u8 id)
{
        struct eap_sim_msg *msg;

        wpa_printf(MSG_DEBUG, "EAP-AKA: Generating Re-authentication");

        if (os_get_random(data->nonce_s, EAP_SIM_NONCE_S_LEN))
                return NULL;
        wpa_hexdump_key(MSG_MSGDUMP, "EAP-AKA: NONCE_S",
                        data->nonce_s, EAP_SIM_NONCE_S_LEN);

        if (data->eap_method == EAP_TYPE_AKA_PRIME) {
                eap_aka_prime_derive_keys_reauth(data->k_re, data->counter,
                                                 sm->identity,
                                                 sm->identity_len,
                                                 data->nonce_s,
                                                 data->msk, data->emsk);
        } else {
                eap_sim_derive_keys(data->mk, data->k_encr, data->k_aut,
                                    data->msk, data->emsk);
                eap_sim_derive_keys_reauth(data->counter, sm->identity,
                                           sm->identity_len, data->nonce_s,
                                           data->mk, data->msk, data->emsk);
        }

        msg = eap_sim_msg_init(EAP_CODE_REQUEST, id, data->eap_method,
                               EAP_AKA_SUBTYPE_REAUTHENTICATION);

        if (eap_aka_build_encr(sm, data, msg, data->counter, data->nonce_s)) {
                eap_sim_msg_free(msg);
                return NULL;
        }

        eap_aka_add_checkcode(data, msg);

        if (sm->eap_sim_aka_result_ind) {
                wpa_printf(MSG_DEBUG, "   AT_RESULT_IND");
                eap_sim_msg_add(msg, EAP_SIM_AT_RESULT_IND, 0, NULL, 0);
        }

        wpa_printf(MSG_DEBUG, "   AT_MAC");
        eap_sim_msg_add_mac(msg, EAP_SIM_AT_MAC);
        return eap_sim_msg_finish(msg, data->k_aut, NULL, 0);
}


static struct wpabuf * eap_aka_build_notification(struct eap_sm *sm,
                                                  struct eap_aka_data *data,
                                                  u8 id)
{
        struct eap_sim_msg *msg;

        wpa_printf(MSG_DEBUG, "EAP-AKA: Generating Notification");
        msg = eap_sim_msg_init(EAP_CODE_REQUEST, id, data->eap_method,
                               EAP_AKA_SUBTYPE_NOTIFICATION);
        wpa_printf(MSG_DEBUG, "   AT_NOTIFICATION (%d)", data->notification);
        eap_sim_msg_add(msg, EAP_SIM_AT_NOTIFICATION, data->notification,
                        NULL, 0);
        if (data->use_result_ind) {
                if (data->reauth) {
                        wpa_printf(MSG_DEBUG, "   AT_IV");
                        wpa_printf(MSG_DEBUG, "   AT_ENCR_DATA");
                        eap_sim_msg_add_encr_start(msg, EAP_SIM_AT_IV,
                                                   EAP_SIM_AT_ENCR_DATA);
                        wpa_printf(MSG_DEBUG, "   *AT_COUNTER (%u)",
                                   data->counter);
                        eap_sim_msg_add(msg, EAP_SIM_AT_COUNTER, data->counter,
                                        NULL, 0);

                        if (eap_sim_msg_add_encr_end(msg, data->k_encr,
                                                     EAP_SIM_AT_PADDING)) {
                                wpa_printf(MSG_WARNING, "EAP-AKA: Failed to "
                                           "encrypt AT_ENCR_DATA");
                                eap_sim_msg_free(msg);
                                return NULL;
                        }
                }

                wpa_printf(MSG_DEBUG, "   AT_MAC");
                eap_sim_msg_add_mac(msg, EAP_SIM_AT_MAC);
        }
        return eap_sim_msg_finish(msg, data->k_aut, NULL, 0);
}


static struct wpabuf * eap_aka_buildReq(struct eap_sm *sm, void *priv, u8 id)
{
        struct eap_aka_data *data = priv;

        data->auts_reported = 0;
        switch (data->state) {
        case IDENTITY:
                return eap_aka_build_identity(sm, data, id);
        case CHALLENGE:
                return eap_aka_build_challenge(sm, data, id);
        case REAUTH:
                return eap_aka_build_reauth(sm, data, id);
        case NOTIFICATION:
                return eap_aka_build_notification(sm, data, id);
        default:
                wpa_printf(MSG_DEBUG, "EAP-AKA: Unknown state %d in "
                           "buildReq", data->state);
                break;
        }
        return NULL;
}


static Boolean eap_aka_check(struct eap_sm *sm, void *priv,
                             struct wpabuf *respData)
{
        struct eap_aka_data *data = priv;
        const u8 *pos;
        size_t len;

        pos = eap_hdr_validate(EAP_VENDOR_IETF, data->eap_method, respData,
                               &len);
        if (pos == NULL || len < 3) {
                wpa_printf(MSG_INFO, "EAP-AKA: Invalid frame");
                return TRUE;
        }

        return FALSE;
}


static Boolean eap_aka_subtype_ok(struct eap_aka_data *data, u8 subtype)
{
        if (subtype == EAP_AKA_SUBTYPE_CLIENT_ERROR ||
            subtype == EAP_AKA_SUBTYPE_AUTHENTICATION_REJECT)
                return FALSE;

        switch (data->state) {
        case IDENTITY:
                if (subtype != EAP_AKA_SUBTYPE_IDENTITY) {
                        wpa_printf(MSG_INFO, "EAP-AKA: Unexpected response "
                                   "subtype %d", subtype);
                        return TRUE;
                }
                break;
        case CHALLENGE:
                if (subtype != EAP_AKA_SUBTYPE_CHALLENGE &&
                    subtype != EAP_AKA_SUBTYPE_SYNCHRONIZATION_FAILURE) {
                        wpa_printf(MSG_INFO, "EAP-AKA: Unexpected response "
                                   "subtype %d", subtype);
                        return TRUE;
                }
                break;
        case REAUTH:
                if (subtype != EAP_AKA_SUBTYPE_REAUTHENTICATION) {
                        wpa_printf(MSG_INFO, "EAP-AKA: Unexpected response "
                                   "subtype %d", subtype);
                        return TRUE;
                }
                break;
        case NOTIFICATION:
                if (subtype != EAP_AKA_SUBTYPE_NOTIFICATION) {
                        wpa_printf(MSG_INFO, "EAP-AKA: Unexpected response "
                                   "subtype %d", subtype);
                        return TRUE;
                }
                break;
        default:
                wpa_printf(MSG_INFO, "EAP-AKA: Unexpected state (%d) for "
                           "processing a response", data->state);
                return TRUE;
        }

        return FALSE;
}


static void eap_aka_determine_identity(struct eap_sm *sm,
                                       struct eap_aka_data *data,
                                       int before_identity, int after_reauth)
{
        const u8 *identity;
        size_t identity_len;
        int res;

        identity = NULL;
        identity_len = 0;

        if (after_reauth && data->reauth) {
                identity = data->reauth->identity;
                identity_len = data->reauth->identity_len;
        } else if (sm->identity && sm->identity_len > 0 &&
                   sm->identity[0] == EAP_AKA_PERMANENT_PREFIX) {
                identity = sm->identity;
                identity_len = sm->identity_len;
        } else {
                identity = eap_sim_db_get_permanent(sm->eap_sim_db_priv,
                                                    sm->identity,
                                                    sm->identity_len,
                                                    &identity_len);
                if (identity == NULL) {
                        data->reauth = eap_sim_db_get_reauth_entry(
                                sm->eap_sim_db_priv, sm->identity,
                                sm->identity_len);
                        if (data->reauth &&
                            data->reauth->aka_prime !=
                            (data->eap_method == EAP_TYPE_AKA_PRIME)) {
                                wpa_printf(MSG_DEBUG, "EAP-AKA: Reauth data "
                                           "was for different AKA version");
                                data->reauth = NULL;
                        }
                        if (data->reauth) {
                                wpa_printf(MSG_DEBUG, "EAP-AKA: Using fast "
                                           "re-authentication");
                                identity = data->reauth->identity;
                                identity_len = data->reauth->identity_len;
                                data->counter = data->reauth->counter;
                                if (data->eap_method == EAP_TYPE_AKA_PRIME) {
                                        os_memcpy(data->k_encr,
                                                  data->reauth->k_encr,
                                                  EAP_SIM_K_ENCR_LEN);
                                        os_memcpy(data->k_aut,
                                                  data->reauth->k_aut,
                                                  EAP_AKA_PRIME_K_AUT_LEN);
                                        os_memcpy(data->k_re,
                                                  data->reauth->k_re,
                                                  EAP_AKA_PRIME_K_RE_LEN);
                                } else {
                                        os_memcpy(data->mk, data->reauth->mk,
                                                  EAP_SIM_MK_LEN);
                                }
                        }
                }
        }

        if (identity == NULL ||
            eap_sim_db_identity_known(sm->eap_sim_db_priv, sm->identity,
                                      sm->identity_len) < 0) {
                if (before_identity) {
                        wpa_printf(MSG_DEBUG, "EAP-AKA: Permanent user name "
                                   "not known - send AKA-Identity request");
                        eap_aka_state(data, IDENTITY);
                        return;
                } else {
                        wpa_printf(MSG_DEBUG, "EAP-AKA: Unknown whether the "
                                   "permanent user name is known; try to use "
                                   "it");
                        /* eap_sim_db_get_aka_auth() will report failure, if
                         * this identity is not known. */
                }
        }

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

        if (!after_reauth && data->reauth) {
                eap_aka_state(data, REAUTH);
                return;
        }

        res = eap_sim_db_get_aka_auth(sm->eap_sim_db_priv, identity,
                                      identity_len, data->rand, data->autn,
                                      data->ik, data->ck, data->res,
                                      &data->res_len, sm);
        if (res == EAP_SIM_DB_PENDING) {
                wpa_printf(MSG_DEBUG, "EAP-AKA: AKA authentication data "
                           "not yet available - pending request");
                sm->method_pending = METHOD_PENDING_WAIT;
                return;
        }

#ifdef EAP_SERVER_AKA_PRIME
        if (data->eap_method == EAP_TYPE_AKA_PRIME) {
                /* Note: AUTN = (SQN ^ AK) || AMF || MAC which gives us the
                 * needed 6-octet SQN ^AK for CK',IK' derivation */
                eap_aka_prime_derive_ck_ik_prime(data->ck, data->ik,
                                                 data->autn,
                                                 data->network_name,
                                                 data->network_name_len);
        }
#endif /* EAP_SERVER_AKA_PRIME */

        data->reauth = NULL;
        data->counter = 0; /* reset re-auth counter since this is full auth */

        if (res != 0) {
                wpa_printf(MSG_INFO, "EAP-AKA: Failed to get AKA "
                           "authentication data for the peer");
                data->notification = EAP_SIM_GENERAL_FAILURE_BEFORE_AUTH;
                eap_aka_state(data, NOTIFICATION);
                return;
        }
        if (sm->method_pending == METHOD_PENDING_WAIT) {
                wpa_printf(MSG_DEBUG, "EAP-AKA: AKA authentication data "
                           "available - abort pending wait");
                sm->method_pending = METHOD_PENDING_NONE;
        }

        identity_len = sm->identity_len;
        while (identity_len > 0 && sm->identity[identity_len - 1] == '\0') {
                wpa_printf(MSG_DEBUG, "EAP-AKA: Workaround - drop last null "
                           "character from identity");
                identity_len--;
        }
        wpa_hexdump_ascii(MSG_DEBUG, "EAP-AKA: Identity for MK derivation",
                          sm->identity, identity_len);

        if (data->eap_method == EAP_TYPE_AKA_PRIME) {
                eap_aka_prime_derive_keys(identity, identity_len, data->ik,
                                          data->ck, data->k_encr, data->k_aut,
                                          data->k_re, data->msk, data->emsk);
        } else {
                eap_aka_derive_mk(sm->identity, identity_len, data->ik,
                                  data->ck, data->mk);
                eap_sim_derive_keys(data->mk, data->k_encr, data->k_aut,
                                    data->msk, data->emsk);
        }

        eap_aka_state(data, CHALLENGE);
}


static void eap_aka_process_identity(struct eap_sm *sm,
                                     struct eap_aka_data *data,
                                     struct wpabuf *respData,
                                     struct eap_sim_attrs *attr)
{
        wpa_printf(MSG_DEBUG, "EAP-AKA: Processing Identity");

        if (attr->mac || attr->iv || attr->encr_data) {
                wpa_printf(MSG_WARNING, "EAP-AKA: Unexpected attribute "
                           "received in EAP-Response/AKA-Identity");
                data->notification = EAP_SIM_GENERAL_FAILURE_BEFORE_AUTH;
                eap_aka_state(data, NOTIFICATION);
                return;
        }

        if (attr->identity) {
                os_free(sm->identity);
                sm->identity = os_malloc(attr->identity_len);
                if (sm->identity) {
                        os_memcpy(sm->identity, attr->identity,
                                  attr->identity_len);
                        sm->identity_len = attr->identity_len;
                }
        }

        eap_aka_determine_identity(sm, data, 0, 0);
        if (eap_get_id(respData) == data->pending_id) {
                data->pending_id = -1;
                eap_aka_add_id_msg(data, respData);
        }
}


static int eap_aka_verify_mac(struct eap_aka_data *data,
                              const struct wpabuf *req,
                              const u8 *mac, const u8 *extra,
                              size_t extra_len)
{
        if (data->eap_method == EAP_TYPE_AKA_PRIME)
                return eap_sim_verify_mac_sha256(data->k_aut, req, mac, extra,
                                                 extra_len);
        return eap_sim_verify_mac(data->k_aut, req, mac, extra, extra_len);
}


static void eap_aka_process_challenge(struct eap_sm *sm,
                                      struct eap_aka_data *data,
                                      struct wpabuf *respData,
                                      struct eap_sim_attrs *attr)
{
        const u8 *identity;
        size_t identity_len;

        wpa_printf(MSG_DEBUG, "EAP-AKA: Processing Challenge");

#ifdef EAP_SERVER_AKA_PRIME
#if 0
        /* KDF negotiation; to be enabled only after more than one KDF is
         * supported */
        if (data->eap_method == EAP_TYPE_AKA_PRIME &&
            attr->kdf_count == 1 && attr->mac == NULL) {
                if (attr->kdf[0] != EAP_AKA_PRIME_KDF) {
                        wpa_printf(MSG_WARNING, "EAP-AKA': Peer selected "
                                   "unknown KDF");
                        data->notification =
                                EAP_SIM_GENERAL_FAILURE_BEFORE_AUTH;
                        eap_aka_state(data, NOTIFICATION);
                        return;
                }

                data->kdf = attr->kdf[0];

                /* Allow negotiation to continue with the selected KDF by
                 * sending another Challenge message */
                wpa_printf(MSG_DEBUG, "EAP-AKA': KDF %d selected", data->kdf);
                return;
        }
#endif
#endif /* EAP_SERVER_AKA_PRIME */

        if (attr->checkcode &&
            eap_aka_verify_checkcode(data, attr->checkcode,
                                     attr->checkcode_len)) {
                wpa_printf(MSG_WARNING, "EAP-AKA: Invalid AT_CHECKCODE in the "
                           "message");
                data->notification = EAP_SIM_GENERAL_FAILURE_BEFORE_AUTH;
                eap_aka_state(data, NOTIFICATION);
                return;
        }
        if (attr->mac == NULL ||
            eap_aka_verify_mac(data, respData, attr->mac, NULL, 0)) {
                wpa_printf(MSG_WARNING, "EAP-AKA: Challenge message "
                           "did not include valid AT_MAC");
                data->notification = EAP_SIM_GENERAL_FAILURE_BEFORE_AUTH;
                eap_aka_state(data, NOTIFICATION);
                return;
        }

        /*
         * AT_RES is padded, so verify that there is enough room for RES and
         * that the RES length in bits matches with the expected RES.
         */
        if (attr->res == NULL || attr->res_len < data->res_len ||
            attr->res_len_bits != data->res_len * 8 ||
            os_memcmp(attr->res, data->res, data->res_len) != 0) {
                wpa_printf(MSG_WARNING, "EAP-AKA: Challenge message did not "
                           "include valid AT_RES (attr len=%lu, res len=%lu "
                           "bits, expected %lu bits)",
                           (unsigned long) attr->res_len,
                           (unsigned long) attr->res_len_bits,
                           (unsigned long) data->res_len * 8);
                data->notification = EAP_SIM_GENERAL_FAILURE_BEFORE_AUTH;
                eap_aka_state(data, NOTIFICATION);
                return;
        }

        wpa_printf(MSG_DEBUG, "EAP-AKA: Challenge response includes the "
                   "correct AT_MAC");
        if (sm->eap_sim_aka_result_ind && attr->result_ind) {
                data->use_result_ind = 1;
                data->notification = EAP_SIM_SUCCESS;
                eap_aka_state(data, NOTIFICATION);
        } else
                eap_aka_state(data, SUCCESS);

        identity = eap_sim_db_get_permanent(sm->eap_sim_db_priv, sm->identity,
                                            sm->identity_len, &identity_len);
        if (identity == NULL) {
                identity = sm->identity;
                identity_len = sm->identity_len;
        }

        if (data->next_pseudonym) {
                eap_sim_db_add_pseudonym(sm->eap_sim_db_priv, identity,
                                         identity_len,
                                         data->next_pseudonym);
                data->next_pseudonym = NULL;
        }
        if (data->next_reauth_id) {
                if (data->eap_method == EAP_TYPE_AKA_PRIME) {
#ifdef EAP_SERVER_AKA_PRIME
                        eap_sim_db_add_reauth_prime(sm->eap_sim_db_priv,
                                                    identity,
                                                    identity_len,
                                                    data->next_reauth_id,
                                                    data->counter + 1,
                                                    data->k_encr, data->k_aut,
                                                    data->k_re);
#endif /* EAP_SERVER_AKA_PRIME */
                } else {
                        eap_sim_db_add_reauth(sm->eap_sim_db_priv, identity,
                                              identity_len,
                                              data->next_reauth_id,
                                              data->counter + 1,
                                              data->mk);
                }
                data->next_reauth_id = NULL;
        }
}


static void eap_aka_process_sync_failure(struct eap_sm *sm,
                                         struct eap_aka_data *data,
                                         struct wpabuf *respData,
                                         struct eap_sim_attrs *attr)
{
        wpa_printf(MSG_DEBUG, "EAP-AKA: Processing Synchronization-Failure");

        if (attr->auts == NULL) {
                wpa_printf(MSG_WARNING, "EAP-AKA: Synchronization-Failure "
                           "message did not include valid AT_AUTS");
                data->notification = EAP_SIM_GENERAL_FAILURE_BEFORE_AUTH;
                eap_aka_state(data, NOTIFICATION);
                return;
        }

        /* Avoid re-reporting AUTS when processing pending EAP packet by
         * maintaining a local flag stating whether this AUTS has already been
         * reported. */
        if (!data->auts_reported &&
            eap_sim_db_resynchronize(sm->eap_sim_db_priv, sm->identity,
                                     sm->identity_len, attr->auts,
                                     data->rand)) {
                wpa_printf(MSG_WARNING, "EAP-AKA: Resynchronization failed");
                data->notification = EAP_SIM_GENERAL_FAILURE_BEFORE_AUTH;
                eap_aka_state(data, NOTIFICATION);
                return;
        }
        data->auts_reported = 1;

        /* Try again after resynchronization */
        eap_aka_determine_identity(sm, data, 0, 0);
}


static void eap_aka_process_reauth(struct eap_sm *sm,
                                   struct eap_aka_data *data,
                                   struct wpabuf *respData,
                                   struct eap_sim_attrs *attr)
{
        struct eap_sim_attrs eattr;
        u8 *decrypted = NULL;
        const u8 *identity, *id2;
        size_t identity_len, id2_len;

        wpa_printf(MSG_DEBUG, "EAP-AKA: Processing Reauthentication");

        if (attr->mac == NULL ||
            eap_aka_verify_mac(data, respData, attr->mac, data->nonce_s,
                               EAP_SIM_NONCE_S_LEN)) {
                wpa_printf(MSG_WARNING, "EAP-AKA: Re-authentication message "
                           "did not include valid AT_MAC");
                goto fail;
        }

        if (attr->encr_data == NULL || attr->iv == NULL) {
                wpa_printf(MSG_WARNING, "EAP-AKA: Reauthentication "
                           "message did not include encrypted data");
                goto fail;
        }

        decrypted = eap_sim_parse_encr(data->k_encr, attr->encr_data,
                                       attr->encr_data_len, attr->iv, &eattr,
                                       0);
        if (decrypted == NULL) {
                wpa_printf(MSG_WARNING, "EAP-AKA: Failed to parse encrypted "
                           "data from reauthentication message");
                goto fail;
        }

        if (eattr.counter != data->counter) {
                wpa_printf(MSG_WARNING, "EAP-AKA: Re-authentication message "
                           "used incorrect counter %u, expected %u",
                           eattr.counter, data->counter);
                goto fail;
        }
        os_free(decrypted);
        decrypted = NULL;

        wpa_printf(MSG_DEBUG, "EAP-AKA: Re-authentication response includes "
                   "the correct AT_MAC");

        if (eattr.counter_too_small) {
                wpa_printf(MSG_DEBUG, "EAP-AKA: Re-authentication response "
                           "included AT_COUNTER_TOO_SMALL - starting full "
                           "authentication");
                eap_aka_determine_identity(sm, data, 0, 1);
                return;
        }

        if (sm->eap_sim_aka_result_ind && attr->result_ind) {
                data->use_result_ind = 1;
                data->notification = EAP_SIM_SUCCESS;
                eap_aka_state(data, NOTIFICATION);
        } else
                eap_aka_state(data, SUCCESS);

        if (data->reauth) {
                identity = data->reauth->identity;
                identity_len = data->reauth->identity_len;
        } else {
                identity = sm->identity;
                identity_len = sm->identity_len;
        }

        id2 = eap_sim_db_get_permanent(sm->eap_sim_db_priv, identity,
                                       identity_len, &id2_len);
        if (id2) {
                identity = id2;
                identity_len = id2_len;
        }

        if (data->next_pseudonym) {
                eap_sim_db_add_pseudonym(sm->eap_sim_db_priv, identity,
                                         identity_len, data->next_pseudonym);
                data->next_pseudonym = NULL;
        }
        if (data->next_reauth_id) {
                if (data->eap_method == EAP_TYPE_AKA_PRIME) {
#ifdef EAP_SERVER_AKA_PRIME
                        eap_sim_db_add_reauth_prime(sm->eap_sim_db_priv,
                                                    identity,
                                                    identity_len,
                                                    data->next_reauth_id,
                                                    data->counter + 1,
                                                    data->k_encr, data->k_aut,
                                                    data->k_re);
#endif /* EAP_SERVER_AKA_PRIME */
                } else {
                        eap_sim_db_add_reauth(sm->eap_sim_db_priv, identity,
                                              identity_len,
                                              data->next_reauth_id,
                                              data->counter + 1,
                                              data->mk);
                }
                data->next_reauth_id = NULL;
        } else {
                eap_sim_db_remove_reauth(sm->eap_sim_db_priv, data->reauth);
                data->reauth = NULL;
        }

        return;

fail:
        data->notification = EAP_SIM_GENERAL_FAILURE_BEFORE_AUTH;
        eap_aka_state(data, NOTIFICATION);
        eap_sim_db_remove_reauth(sm->eap_sim_db_priv, data->reauth);
        data->reauth = NULL;
        os_free(decrypted);
}


static void eap_aka_process_client_error(struct eap_sm *sm,
                                         struct eap_aka_data *data,
                                         struct wpabuf *respData,
                                         struct eap_sim_attrs *attr)
{
        wpa_printf(MSG_DEBUG, "EAP-AKA: Client reported error %d",
                   attr->client_error_code);
        if (data->notification == EAP_SIM_SUCCESS && data->use_result_ind)
                eap_aka_state(data, SUCCESS);
        else
                eap_aka_state(data, FAILURE);
}


static void eap_aka_process_authentication_reject(
        struct eap_sm *sm, struct eap_aka_data *data,
        struct wpabuf *respData, struct eap_sim_attrs *attr)
{
        wpa_printf(MSG_DEBUG, "EAP-AKA: Client rejected authentication");
        eap_aka_state(data, FAILURE);
}


static void eap_aka_process_notification(struct eap_sm *sm,
                                         struct eap_aka_data *data,
                                         struct wpabuf *respData,
                                         struct eap_sim_attrs *attr)
{
        wpa_printf(MSG_DEBUG, "EAP-AKA: Client replied to notification");
        if (data->notification == EAP_SIM_SUCCESS && data->use_result_ind)
                eap_aka_state(data, SUCCESS);
        else
                eap_aka_state(data, FAILURE);
}


static void eap_aka_process(struct eap_sm *sm, void *priv,
                            struct wpabuf *respData)
{
        struct eap_aka_data *data = priv;
        const u8 *pos, *end;
        u8 subtype;
        size_t len;
        struct eap_sim_attrs attr;

        pos = eap_hdr_validate(EAP_VENDOR_IETF, data->eap_method, respData,
                               &len);
        if (pos == NULL || len < 3)
                return;

        end = pos + len;
        subtype = *pos;
        pos += 3;

        if (eap_aka_subtype_ok(data, subtype)) {
                wpa_printf(MSG_DEBUG, "EAP-AKA: Unrecognized or unexpected "
                           "EAP-AKA Subtype in EAP Response");
                data->notification = EAP_SIM_GENERAL_FAILURE_BEFORE_AUTH;
                eap_aka_state(data, NOTIFICATION);
                return;
        }

        if (eap_sim_parse_attr(pos, end, &attr,
                               data->eap_method == EAP_TYPE_AKA_PRIME ? 2 : 1,
                               0)) {
                wpa_printf(MSG_DEBUG, "EAP-AKA: Failed to parse attributes");
                data->notification = EAP_SIM_GENERAL_FAILURE_BEFORE_AUTH;
                eap_aka_state(data, NOTIFICATION);
                return;
        }

        if (subtype == EAP_AKA_SUBTYPE_CLIENT_ERROR) {
                eap_aka_process_client_error(sm, data, respData, &attr);
                return;
        }

        if (subtype == EAP_AKA_SUBTYPE_AUTHENTICATION_REJECT) {
                eap_aka_process_authentication_reject(sm, data, respData,
                                                      &attr);
                return;
        }

        switch (data->state) {
        case IDENTITY:
                eap_aka_process_identity(sm, data, respData, &attr);
                break;
        case CHALLENGE:
                if (subtype == EAP_AKA_SUBTYPE_SYNCHRONIZATION_FAILURE) {
                        eap_aka_process_sync_failure(sm, data, respData,
                                                     &attr);
                } else {
                        eap_aka_process_challenge(sm, data, respData, &attr);
                }
                break;
        case REAUTH:
                eap_aka_process_reauth(sm, data, respData, &attr);
                break;
        case NOTIFICATION:
                eap_aka_process_notification(sm, data, respData, &attr);
                break;
        default:
                wpa_printf(MSG_DEBUG, "EAP-AKA: Unknown state %d in "
                           "process", data->state);
                break;
        }
}


static Boolean eap_aka_isDone(struct eap_sm *sm, void *priv)
{
        struct eap_aka_data *data = priv;
        return data->state == SUCCESS || data->state == FAILURE;
}


static u8 * eap_aka_getKey(struct eap_sm *sm, void *priv, size_t *len)
{
        struct eap_aka_data *data = priv;
        u8 *key;

        if (data->state != SUCCESS)
                return NULL;

        key = os_malloc(EAP_SIM_KEYING_DATA_LEN);
        if (key == NULL)
                return NULL;
        os_memcpy(key, data->msk, EAP_SIM_KEYING_DATA_LEN);
        *len = EAP_SIM_KEYING_DATA_LEN;
        return key;
}


static u8 * eap_aka_get_emsk(struct eap_sm *sm, void *priv, size_t *len)
{
        struct eap_aka_data *data = priv;
        u8 *key;

        if (data->state != SUCCESS)
                return NULL;

        key = os_malloc(EAP_EMSK_LEN);
        if (key == NULL)
                return NULL;
        os_memcpy(key, data->emsk, EAP_EMSK_LEN);
        *len = EAP_EMSK_LEN;
        return key;
}


static Boolean eap_aka_isSuccess(struct eap_sm *sm, void *priv)
{
        struct eap_aka_data *data = priv;
        return data->state == SUCCESS;
}


int eap_server_aka_register(void)
{
        struct eap_method *eap;
        int ret;

        eap = eap_server_method_alloc(EAP_SERVER_METHOD_INTERFACE_VERSION,
                                      EAP_VENDOR_IETF, EAP_TYPE_AKA, "AKA");
        if (eap == NULL)
                return -1;

        eap->init = eap_aka_init;
        eap->reset = eap_aka_reset;
        eap->buildReq = eap_aka_buildReq;
        eap->check = eap_aka_check;
        eap->process = eap_aka_process;
        eap->isDone = eap_aka_isDone;
        eap->getKey = eap_aka_getKey;
        eap->isSuccess = eap_aka_isSuccess;
        eap->get_emsk = eap_aka_get_emsk;

        ret = eap_server_method_register(eap);
        if (ret)
                eap_server_method_free(eap);
        return ret;
}


#ifdef EAP_SERVER_AKA_PRIME
int eap_server_aka_prime_register(void)
{
        struct eap_method *eap;
        int ret;

        eap = eap_server_method_alloc(EAP_SERVER_METHOD_INTERFACE_VERSION,
                                      EAP_VENDOR_IETF, EAP_TYPE_AKA_PRIME,
                                      "AKA'");
        if (eap == NULL)
                return -1;

        eap->init = eap_aka_prime_init;
        eap->reset = eap_aka_reset;
        eap->buildReq = eap_aka_buildReq;
        eap->check = eap_aka_check;
        eap->process = eap_aka_process;
        eap->isDone = eap_aka_isDone;
        eap->getKey = eap_aka_getKey;
        eap->isSuccess = eap_aka_isSuccess;
        eap->get_emsk = eap_aka_get_emsk;

        ret = eap_server_method_register(eap);
        if (ret)
                eap_server_method_free(eap);

        return ret;
}
#endif /* EAP_SERVER_AKA_PRIME */