text: /*
   * hostapd / EAP-PAX (RFC 4746) server
   * Copyright (c) 2005-2007, Jouni Malinen <j@w1.fi>
   *
   * This software may be distributed under the terms of the BSD license.
   * See README for more details.
   */
  
  #include "includes.h"
  
  #include "common.h"
  #include "crypto/random.h"
  #include "eap_server/eap_i.h"
  #include "eap_common/eap_pax_common.h"
  
  /*
   * Note: only PAX_STD subprotocol is currently supported
   *
   * TODO: Add support with PAX_SEC with the mandatory to implement ciphersuite
   * (HMAC_SHA1_128, IANA DH Group 14 (2048 bits), RSA-PKCS1-V1_5) and
   * recommended ciphersuite (HMAC_SHA256_128, IANA DH Group 15 (3072 bits),
   * RSAES-OAEP).
   */
  
  struct eap_pax_data {
  	enum { PAX_STD_1, PAX_STD_3, SUCCESS, FAILURE } state;
  	u8 mac_id;
  	union {
  		u8 e[2 * EAP_PAX_RAND_LEN];
  		struct {
  			u8 x[EAP_PAX_RAND_LEN]; /* server rand */
  			u8 y[EAP_PAX_RAND_LEN]; /* client rand */
  		} r;
  	} rand;
  	u8 ak[EAP_PAX_AK_LEN];
  	u8 mk[EAP_PAX_MK_LEN];
  	u8 ck[EAP_PAX_CK_LEN];
  	u8 ick[EAP_PAX_ICK_LEN];
  	int keys_set;
  	char *cid;
  	size_t cid_len;
  };
  
  
  static void * eap_pax_init(struct eap_sm *sm)
  {
  	struct eap_pax_data *data;
  
  	data = os_zalloc(sizeof(*data));
  	if (data == NULL)
  		return NULL;
  	data->state = PAX_STD_1;
  	/*
  	 * TODO: make this configurable once EAP_PAX_HMAC_SHA256_128 is
  	 * supported
  	 */
  	data->mac_id = EAP_PAX_MAC_HMAC_SHA1_128;
  
  	return data;
  }
  
  
  static void eap_pax_reset(struct eap_sm *sm, void *priv)
  {
  	struct eap_pax_data *data = priv;
  	os_free(data->cid);
  	os_free(data);
  }
  
  
  static struct wpabuf * eap_pax_build_std_1(struct eap_sm *sm,
  					   struct eap_pax_data *data, u8 id)
  {
  	struct wpabuf *req;
  	struct eap_pax_hdr *pax;
  	u8 *pos;
  
  	wpa_printf(MSG_DEBUG, "EAP-PAX: PAX_STD-1 (sending)");
  
  	if (random_get_bytes(data->rand.r.x, EAP_PAX_RAND_LEN)) {
  		wpa_printf(MSG_ERROR, "EAP-PAX: Failed to get random data");
  		data->state = FAILURE;
  		return NULL;
  	}
  
  	req = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_PAX,
  			    sizeof(*pax) + 2 + EAP_PAX_RAND_LEN +
  			    EAP_PAX_ICV_LEN, EAP_CODE_REQUEST, id);
  	if (req == NULL) {
  		wpa_printf(MSG_ERROR, "EAP-PAX: Failed to allocate memory "
  			   "request");
  		data->state = FAILURE;
  		return NULL;
  	}
  
  	pax = wpabuf_put(req, sizeof(*pax));
  	pax->op_code = EAP_PAX_OP_STD_1;
  	pax->flags = 0;
  	pax->mac_id = data->mac_id;
  	pax->dh_group_id = EAP_PAX_DH_GROUP_NONE;
  	pax->public_key_id = EAP_PAX_PUBLIC_KEY_NONE;
  
  	wpabuf_put_be16(req, EAP_PAX_RAND_LEN);
  	wpabuf_put_data(req, data->rand.r.x, EAP_PAX_RAND_LEN);
  	wpa_hexdump(MSG_MSGDUMP, "EAP-PAX: A = X (server rand)",
  		    data->rand.r.x, EAP_PAX_RAND_LEN);
  
  	pos = wpabuf_put(req, EAP_PAX_MAC_LEN);
  	eap_pax_mac(data->mac_id, (u8 *) "", 0,
  		    wpabuf_mhead(req), wpabuf_len(req) - EAP_PAX_ICV_LEN,
  		    NULL, 0, NULL, 0, pos);
  	wpa_hexdump(MSG_MSGDUMP, "EAP-PAX: ICV", pos, EAP_PAX_ICV_LEN);
  
  	return req;
  }
  
  
  static struct wpabuf * eap_pax_build_std_3(struct eap_sm *sm,
  					   struct eap_pax_data *data, u8 id)
  {
  	struct wpabuf *req;
  	struct eap_pax_hdr *pax;
  	u8 *pos;
  
  	wpa_printf(MSG_DEBUG, "EAP-PAX: PAX_STD-3 (sending)");
  
  	req = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_PAX,
  			    sizeof(*pax) + 2 + EAP_PAX_MAC_LEN +
  			    EAP_PAX_ICV_LEN, EAP_CODE_REQUEST, id);
  	if (req == NULL) {
  		wpa_printf(MSG_ERROR, "EAP-PAX: Failed to allocate memory "
  			   "request");
  		data->state = FAILURE;
  		return NULL;
  	}
  
  	pax = wpabuf_put(req, sizeof(*pax));
  	pax->op_code = EAP_PAX_OP_STD_3;
  	pax->flags = 0;
  	pax->mac_id = data->mac_id;
  	pax->dh_group_id = EAP_PAX_DH_GROUP_NONE;
  	pax->public_key_id = EAP_PAX_PUBLIC_KEY_NONE;
  
  	wpabuf_put_be16(req, EAP_PAX_MAC_LEN);
  	pos = wpabuf_put(req, EAP_PAX_MAC_LEN);
  	eap_pax_mac(data->mac_id, data->ck, EAP_PAX_CK_LEN,
  		    data->rand.r.y, EAP_PAX_RAND_LEN,
  		    (u8 *) data->cid, data->cid_len, NULL, 0, pos);
  	wpa_hexdump(MSG_MSGDUMP, "EAP-PAX: MAC_CK(B, CID)",
  		    pos, EAP_PAX_MAC_LEN);
  	pos += EAP_PAX_MAC_LEN;
  
  	/* Optional ADE could be added here, if needed */
  
  	pos = wpabuf_put(req, EAP_PAX_MAC_LEN);
  	eap_pax_mac(data->mac_id, data->ick, EAP_PAX_ICK_LEN,
  		    wpabuf_mhead(req), wpabuf_len(req) - EAP_PAX_ICV_LEN,
  		    NULL, 0, NULL, 0, pos);
  	wpa_hexdump(MSG_MSGDUMP, "EAP-PAX: ICV", pos, EAP_PAX_ICV_LEN);
  
  	return req;
  }
  
  
  static struct wpabuf * eap_pax_buildReq(struct eap_sm *sm, void *priv, u8 id)
  {
  	struct eap_pax_data *data = priv;
  
  	switch (data->state) {
  	case PAX_STD_1:
  		return eap_pax_build_std_1(sm, data, id);
  	case PAX_STD_3:
  		return eap_pax_build_std_3(sm, data, id);
  	default:
  		wpa_printf(MSG_DEBUG, "EAP-PAX: Unknown state %d in buildReq",
  			   data->state);
  		break;
  	}
  	return NULL;
  }
  
  
  static Boolean eap_pax_check(struct eap_sm *sm, void *priv,
  			     struct wpabuf *respData)
  {
  	struct eap_pax_data *data = priv;
  	struct eap_pax_hdr *resp;
  	const u8 *pos;
  	size_t len, mlen;
  	u8 icvbuf[EAP_PAX_ICV_LEN], *icv;
  
  	pos = eap_hdr_validate(EAP_VENDOR_IETF, EAP_TYPE_PAX, respData, &len);
  	if (pos == NULL || len < sizeof(*resp)) {
  		wpa_printf(MSG_INFO, "EAP-PAX: Invalid frame");
  		return TRUE;
  	}
  
  	mlen = sizeof(struct eap_hdr) + 1 + len;
  	resp = (struct eap_pax_hdr *) pos;
  
  	wpa_printf(MSG_DEBUG, "EAP-PAX: received frame: op_code 0x%x "
  		   "flags 0x%x mac_id 0x%x dh_group_id 0x%x "
  		   "public_key_id 0x%x",
  		   resp->op_code, resp->flags, resp->mac_id, resp->dh_group_id,
  		   resp->public_key_id);
  	wpa_hexdump(MSG_MSGDUMP, "EAP-PAX: received payload",
  		    (u8 *) (resp + 1), len - sizeof(*resp) - EAP_PAX_ICV_LEN);
  
  	if (data->state == PAX_STD_1 &&
  	    resp->op_code != EAP_PAX_OP_STD_2) {
  		wpa_printf(MSG_DEBUG, "EAP-PAX: Expected PAX_STD-2 - "
  			   "ignore op %d", resp->op_code);
  		return TRUE;
  	}
  
  	if (data->state == PAX_STD_3 &&
  	    resp->op_code != EAP_PAX_OP_ACK) {
  		wpa_printf(MSG_DEBUG, "EAP-PAX: Expected PAX-ACK - "
  			   "ignore op %d", resp->op_code);
  		return TRUE;
  	}
  
  	if (resp->op_code != EAP_PAX_OP_STD_2 &&
  	    resp->op_code != EAP_PAX_OP_ACK) {
  		wpa_printf(MSG_DEBUG, "EAP-PAX: Unknown op_code 0x%x",
  			   resp->op_code);
  	}
  
  	if (data->mac_id != resp->mac_id) {
  		wpa_printf(MSG_DEBUG, "EAP-PAX: Expected MAC ID 0x%x, "
  			   "received 0x%x", data->mac_id, resp->mac_id);
  		return TRUE;
  	}
  
  	if (resp->dh_group_id != EAP_PAX_DH_GROUP_NONE) {
  		wpa_printf(MSG_INFO, "EAP-PAX: Expected DH Group ID 0x%x, "
  			   "received 0x%x", EAP_PAX_DH_GROUP_NONE,
  			   resp->dh_group_id);
  		return TRUE;
  	}
  
  	if (resp->public_key_id != EAP_PAX_PUBLIC_KEY_NONE) {
  		wpa_printf(MSG_INFO, "EAP-PAX: Expected Public Key ID 0x%x, "
  			   "received 0x%x", EAP_PAX_PUBLIC_KEY_NONE,
  			   resp->public_key_id);
  		return TRUE;
  	}
  
  	if (resp->flags & EAP_PAX_FLAGS_MF) {
  		/* TODO: add support for reassembling fragments */
  		wpa_printf(MSG_INFO, "EAP-PAX: fragmentation not supported");
  		return TRUE;
  	}
  
  	if (resp->flags & EAP_PAX_FLAGS_CE) {
  		wpa_printf(MSG_INFO, "EAP-PAX: Unexpected CE flag");
  		return TRUE;
  	}
  
  	if (data->keys_set) {
  		if (len - sizeof(*resp) < EAP_PAX_ICV_LEN) {
  			wpa_printf(MSG_INFO, "EAP-PAX: No ICV in the packet");
  			return TRUE;
  		}
  		icv = wpabuf_mhead_u8(respData) + mlen - EAP_PAX_ICV_LEN;
  		wpa_hexdump(MSG_MSGDUMP, "EAP-PAX: ICV", icv, EAP_PAX_ICV_LEN);
  		eap_pax_mac(data->mac_id, data->ick, EAP_PAX_ICK_LEN,
  			    wpabuf_mhead(respData),
  			    wpabuf_len(respData) - EAP_PAX_ICV_LEN,
  			    NULL, 0, NULL, 0, icvbuf);
  		if (os_memcmp(icvbuf, icv, EAP_PAX_ICV_LEN) != 0) {
  			wpa_printf(MSG_INFO, "EAP-PAX: Invalid ICV");
  			wpa_hexdump(MSG_MSGDUMP, "EAP-PAX: Expected ICV",
  				    icvbuf, EAP_PAX_ICV_LEN);
  			return TRUE;
  		}
  	}
  
  	return FALSE;
  }
  
  
  static void eap_pax_process_std_2(struct eap_sm *sm,
  				  struct eap_pax_data *data,
  				  struct wpabuf *respData)
  {
  	struct eap_pax_hdr *resp;
  	u8 mac[EAP_PAX_MAC_LEN], icvbuf[EAP_PAX_ICV_LEN];
  	const u8 *pos;
  	size_t len, left;
  	int i;
  
  	if (data->state != PAX_STD_1)
  		return;
  
  	wpa_printf(MSG_DEBUG, "EAP-PAX: Received PAX_STD-2");
  
  	pos = eap_hdr_validate(EAP_VENDOR_IETF, EAP_TYPE_PAX, respData, &len);
  	if (pos == NULL || len < sizeof(*resp) + EAP_PAX_ICV_LEN)
  		return;
  
  	resp = (struct eap_pax_hdr *) pos;
  	pos = (u8 *) (resp + 1);
  	left = len - sizeof(*resp);
  
  	if (left < 2 + EAP_PAX_RAND_LEN ||
  	    WPA_GET_BE16(pos) != EAP_PAX_RAND_LEN) {
  		wpa_printf(MSG_INFO, "EAP-PAX: Too short PAX_STD-2 (B)");
  		return;
  	}
  	pos += 2;
  	left -= 2;
  	os_memcpy(data->rand.r.y, pos, EAP_PAX_RAND_LEN);
  	wpa_hexdump(MSG_MSGDUMP, "EAP-PAX: Y (client rand)",
  		    data->rand.r.y, EAP_PAX_RAND_LEN);
  	pos += EAP_PAX_RAND_LEN;
  	left -= EAP_PAX_RAND_LEN;
  
  	if (left < 2 || (size_t) 2 + WPA_GET_BE16(pos) > left) {
  		wpa_printf(MSG_INFO, "EAP-PAX: Too short PAX_STD-2 (CID)");
  		return;
  	}
  	data->cid_len = WPA_GET_BE16(pos);
  	os_free(data->cid);
  	data->cid = os_malloc(data->cid_len);
  	if (data->cid == NULL) {
  		wpa_printf(MSG_INFO, "EAP-PAX: Failed to allocate memory for "
  			   "CID");
  		return;
  	}
  	os_memcpy(data->cid, pos + 2, data->cid_len);
  	pos += 2 + data->cid_len;
  	left -= 2 + data->cid_len;
  	wpa_hexdump_ascii(MSG_MSGDUMP, "EAP-PAX: CID",
  			  (u8 *) data->cid, data->cid_len);
  
  	if (left < 2 + EAP_PAX_MAC_LEN ||
  	    WPA_GET_BE16(pos) != EAP_PAX_MAC_LEN) {
  		wpa_printf(MSG_INFO, "EAP-PAX: Too short PAX_STD-2 (MAC_CK)");
  		return;
  	}
  	pos += 2;
  	left -= 2;
  	wpa_hexdump(MSG_MSGDUMP, "EAP-PAX: MAC_CK(A, B, CID)",
  		    pos, EAP_PAX_MAC_LEN);
  
  	if (eap_user_get(sm, (u8 *) data->cid, data->cid_len, 0) < 0) {
  		wpa_hexdump_ascii(MSG_DEBUG, "EAP-PAX: unknown CID",
  				  (u8 *) data->cid, data->cid_len);
  		data->state = FAILURE;
  		return;
  	}
  
  	for (i = 0;
  	     i < EAP_MAX_METHODS &&
  		     (sm->user->methods[i].vendor != EAP_VENDOR_IETF ||
  		      sm->user->methods[i].method != EAP_TYPE_NONE);
  	     i++) {
  		if (sm->user->methods[i].vendor == EAP_VENDOR_IETF &&
  		    sm->user->methods[i].method == EAP_TYPE_PAX)
  			break;
  	}
  
  	if (i >= EAP_MAX_METHODS ||
  	    sm->user->methods[i].vendor != EAP_VENDOR_IETF ||
  	    sm->user->methods[i].method != EAP_TYPE_PAX) {
  		wpa_hexdump_ascii(MSG_DEBUG,
  				  "EAP-PAX: EAP-PAX not enabled for CID",
  				  (u8 *) data->cid, data->cid_len);
  		data->state = FAILURE;
  		return;
  	}
  
  	if (sm->user->password == NULL ||
  	    sm->user->password_len != EAP_PAX_AK_LEN) {
  		wpa_hexdump_ascii(MSG_DEBUG, "EAP-PAX: invalid password in "
  				  "user database for CID",
  				  (u8 *) data->cid, data->cid_len);
  		data->state = FAILURE;
  		return;
  	}
  	os_memcpy(data->ak, sm->user->password, EAP_PAX_AK_LEN);
  
  	if (eap_pax_initial_key_derivation(data->mac_id, data->ak,
  					   data->rand.e, data->mk, data->ck,
  					   data->ick) < 0) {
  		wpa_printf(MSG_INFO, "EAP-PAX: Failed to complete initial "
  			   "key derivation");
  		data->state = FAILURE;
  		return;
  	}
  	data->keys_set = 1;
  
  	eap_pax_mac(data->mac_id, data->ck, EAP_PAX_CK_LEN,
  		    data->rand.r.x, EAP_PAX_RAND_LEN,
  		    data->rand.r.y, EAP_PAX_RAND_LEN,
  		    (u8 *) data->cid, data->cid_len, mac);
  	if (os_memcmp(mac, pos, EAP_PAX_MAC_LEN) != 0) {
  		wpa_printf(MSG_INFO, "EAP-PAX: Invalid MAC_CK(A, B, CID) in "
  			   "PAX_STD-2");
  		wpa_hexdump(MSG_MSGDUMP, "EAP-PAX: Expected MAC_CK(A, B, CID)",
  			    mac, EAP_PAX_MAC_LEN);
  		data->state = FAILURE;
  		return;
  	}
  
  	pos += EAP_PAX_MAC_LEN;
  	left -= EAP_PAX_MAC_LEN;
  
  	if (left < EAP_PAX_ICV_LEN) {
  		wpa_printf(MSG_INFO, "EAP-PAX: Too short ICV (%lu) in "
  			   "PAX_STD-2", (unsigned long) left);
  		return;
  	}
  	wpa_hexdump(MSG_MSGDUMP, "EAP-PAX: ICV", pos, EAP_PAX_ICV_LEN);
  	eap_pax_mac(data->mac_id, data->ick, EAP_PAX_ICK_LEN,
  		    wpabuf_head(respData),
  		    wpabuf_len(respData) - EAP_PAX_ICV_LEN, NULL, 0, NULL, 0,
  		    icvbuf);
  	if (os_memcmp(icvbuf, pos, EAP_PAX_ICV_LEN) != 0) {
  		wpa_printf(MSG_INFO, "EAP-PAX: Invalid ICV in PAX_STD-2");
  		wpa_hexdump(MSG_MSGDUMP, "EAP-PAX: Expected ICV",
  			    icvbuf, EAP_PAX_ICV_LEN);
  		return;
  	}
  	pos += EAP_PAX_ICV_LEN;
  	left -= EAP_PAX_ICV_LEN;
  
  	if (left > 0) {
  		wpa_hexdump(MSG_MSGDUMP, "EAP-PAX: ignored extra payload",
  			    pos, left);
  	}
  
  	data->state = PAX_STD_3;
  }
  
  
  static void eap_pax_process_ack(struct eap_sm *sm,
  				struct eap_pax_data *data,
  				struct wpabuf *respData)
  {
  	if (data->state != PAX_STD_3)
  		return;
  
  	wpa_printf(MSG_DEBUG, "EAP-PAX: Received PAX-ACK - authentication "
  		   "completed successfully");
  	data->state = SUCCESS;
  }
  
  
  static void eap_pax_process(struct eap_sm *sm, void *priv,
  			    struct wpabuf *respData)
  {
  	struct eap_pax_data *data = priv;
  	struct eap_pax_hdr *resp;
  	const u8 *pos;
  	size_t len;
  
  	if (sm->user == NULL || sm->user->password == NULL) {
  		wpa_printf(MSG_INFO, "EAP-PAX: Plaintext password not "
  			   "configured");
  		data->state = FAILURE;
  		return;
  	}
  
  	pos = eap_hdr_validate(EAP_VENDOR_IETF, EAP_TYPE_PAX, respData, &len);
  	if (pos == NULL || len < sizeof(*resp))
  		return;
  
  	resp = (struct eap_pax_hdr *) pos;
  
  	switch (resp->op_code) {
  	case EAP_PAX_OP_STD_2:
  		eap_pax_process_std_2(sm, data, respData);
  		break;
  	case EAP_PAX_OP_ACK:
  		eap_pax_process_ack(sm, data, respData);
  		break;
  	}
  }
  
  
  static Boolean eap_pax_isDone(struct eap_sm *sm, void *priv)
  {
  	struct eap_pax_data *data = priv;
  	return data->state == SUCCESS || data->state == FAILURE;
  }
  
  
  static u8 * eap_pax_getKey(struct eap_sm *sm, void *priv, size_t *len)
  {
  	struct eap_pax_data *data = priv;
  	u8 *key;
  
  	if (data->state != SUCCESS)
  		return NULL;
  
  	key = os_malloc(EAP_MSK_LEN);
  	if (key == NULL)
  		return NULL;
  
  	*len = EAP_MSK_LEN;
  	eap_pax_kdf(data->mac_id, data->mk, EAP_PAX_MK_LEN,
  		    "Master Session Key", data->rand.e, 2 * EAP_PAX_RAND_LEN,
  		    EAP_MSK_LEN, key);
  
  	return key;
  }
  
  
  static u8 * eap_pax_get_emsk(struct eap_sm *sm, void *priv, size_t *len)
  {
  	struct eap_pax_data *data = priv;
  	u8 *key;
  
  	if (data->state != SUCCESS)
  		return NULL;
  
  	key = os_malloc(EAP_EMSK_LEN);
  	if (key == NULL)
  		return NULL;
  
  	*len = EAP_EMSK_LEN;
  	eap_pax_kdf(data->mac_id, data->mk, EAP_PAX_MK_LEN,
  		    "Extended Master Session Key",
  		    data->rand.e, 2 * EAP_PAX_RAND_LEN,
  		    EAP_EMSK_LEN, key);
  
  	return key;
  }
  
  
  static Boolean eap_pax_isSuccess(struct eap_sm *sm, void *priv)
  {
  	struct eap_pax_data *data = priv;
  	return data->state == SUCCESS;
  }
  
  
  int eap_server_pax_register(void)
  {
  	struct eap_method *eap;
  	int ret;
  
  	eap = eap_server_method_alloc(EAP_SERVER_METHOD_INTERFACE_VERSION,
  				      EAP_VENDOR_IETF, EAP_TYPE_PAX, "PAX");
  	if (eap == NULL)
  		return -1;
  
  	eap->init = eap_pax_init;
  	eap->reset = eap_pax_reset;
  	eap->buildReq = eap_pax_buildReq;
  	eap->check = eap_pax_check;
  	eap->process = eap_pax_process;
  	eap->isDone = eap_pax_isDone;
  	eap->getKey = eap_pax_getKey;
  	eap->isSuccess = eap_pax_isSuccess;
  	eap->get_emsk = eap_pax_get_emsk;
  
  	ret = eap_server_method_register(eap);
  	if (ret)
  		eap_server_method_free(eap);
  	return ret;
  }
  