text: /*
   * hostapd / EAP-pwd (RFC 5931) server
   * Copyright (c) 2010, Dan Harkins <dharkins@lounge.org>
   *
   * 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/sha256.h"
  #include "crypto/ms_funcs.h"
  #include "crypto/crypto.h"
  #include "eap_server/eap_i.h"
  #include "eap_common/eap_pwd_common.h"
  
  
  struct eap_pwd_data {
  	enum {
  		PWD_ID_Req, PWD_Commit_Req, PWD_Confirm_Req, SUCCESS, FAILURE
  	} state;
  	u8 *id_peer;
  	size_t id_peer_len;
  	u8 *id_server;
  	size_t id_server_len;
  	u8 *password;
  	size_t password_len;
  	int password_hash;
  	u8 *salt;
  	size_t salt_len;
  	u32 token;
  	u16 group_num;
  	u8 password_prep;
  	EAP_PWD_group *grp;
  
  	struct wpabuf *inbuf;
  	size_t in_frag_pos;
  	struct wpabuf *outbuf;
  	size_t out_frag_pos;
  	size_t mtu;
  
  	struct crypto_bignum *k;
  	struct crypto_bignum *private_value;
  	struct crypto_bignum *peer_scalar;
  	struct crypto_bignum *my_scalar;
  	struct crypto_ec_point *my_element;
  	struct crypto_ec_point *peer_element;
  
  	u8 my_confirm[SHA256_MAC_LEN];
  
  	u8 msk[EAP_MSK_LEN];
  	u8 emsk[EAP_EMSK_LEN];
  	u8 session_id[1 + SHA256_MAC_LEN];
  };
  
  
  static const char * eap_pwd_state_txt(int state)
  {
  	switch (state) {
          case PWD_ID_Req:
  		return "PWD-ID-Req";
          case PWD_Commit_Req:
  		return "PWD-Commit-Req";
          case PWD_Confirm_Req:
  		return "PWD-Confirm-Req";
          case SUCCESS:
  		return "SUCCESS";
          case FAILURE:
  		return "FAILURE";
          default:
  		return "PWD-Unk";
  	}
  }
  
  
  static void eap_pwd_state(struct eap_pwd_data *data, int state)
  {
  	wpa_printf(MSG_DEBUG, "EAP-pwd: %s -> %s",
  		   eap_pwd_state_txt(data->state), eap_pwd_state_txt(state));
  	data->state = state;
  }
  
  
  static void * eap_pwd_init(struct eap_sm *sm)
  {
  	struct eap_pwd_data *data;
  
  	if (sm->user == NULL || sm->user->password == NULL ||
  	    sm->user->password_len == 0) {
  		wpa_printf(MSG_INFO, "EAP-PWD (server): Password is not "
  			   "configured");
  		return NULL;
  	}
  
  	data = os_zalloc(sizeof(*data));
  	if (data == NULL)
  		return NULL;
  
  	data->group_num = sm->pwd_group;
  	wpa_printf(MSG_DEBUG, "EAP-pwd: Selected group number %d",
  		   data->group_num);
  	data->state = PWD_ID_Req;
  
  	data->id_server = (u8 *) os_strdup("server");
  	if (data->id_server)
  		data->id_server_len = os_strlen((char *) data->id_server);
  
  	data->password = os_malloc(sm->user->password_len);
  	if (data->password == NULL) {
  		wpa_printf(MSG_INFO, "EAP-PWD: Memory allocation password "
  			   "fail");
  		bin_clear_free(data->id_server, data->id_server_len);
  		os_free(data);
  		return NULL;
  	}
  	data->password_len = sm->user->password_len;
  	os_memcpy(data->password, sm->user->password, data->password_len);
  	data->password_hash = sm->user->password_hash;
  
  	data->salt_len = sm->user->salt_len;
  	if (data->salt_len) {
  		data->salt = os_memdup(sm->user->salt, sm->user->salt_len);
  		if (!data->salt) {
  			wpa_printf(MSG_INFO,
  				   "EAP-pwd: Memory allocation of salt failed");
  			bin_clear_free(data->id_server, data->id_server_len);
  			bin_clear_free(data->password, data->password_len);
  			os_free(data);
  			return NULL;
  		}
  	}
  
  	data->in_frag_pos = data->out_frag_pos = 0;
  	data->inbuf = data->outbuf = NULL;
  	/* use default MTU from RFC 5931 if not configured otherwise */
  	data->mtu = sm->fragment_size > 0 ? sm->fragment_size : 1020;
  
  	return data;
  }
  
  
  static void eap_pwd_reset(struct eap_sm *sm, void *priv)
  {
  	struct eap_pwd_data *data = priv;
  
  	crypto_bignum_deinit(data->private_value, 1);
  	crypto_bignum_deinit(data->peer_scalar, 1);
  	crypto_bignum_deinit(data->my_scalar, 1);
  	crypto_bignum_deinit(data->k, 1);
  	crypto_ec_point_deinit(data->my_element, 1);
  	crypto_ec_point_deinit(data->peer_element, 1);
  	bin_clear_free(data->id_peer, data->id_peer_len);
  	bin_clear_free(data->id_server, data->id_server_len);
  	bin_clear_free(data->password, data->password_len);
  	bin_clear_free(data->salt, data->salt_len);
  	if (data->grp) {
  		crypto_ec_deinit(data->grp->group);
  		crypto_ec_point_deinit(data->grp->pwe, 1);
  		os_free(data->grp);
  	}
  	wpabuf_free(data->inbuf);
  	wpabuf_free(data->outbuf);
  	bin_clear_free(data, sizeof(*data));
  }
  
  
  static void eap_pwd_build_id_req(struct eap_sm *sm, struct eap_pwd_data *data,
  				 u8 id)
  {
  	wpa_printf(MSG_DEBUG, "EAP-pwd: ID/Request");
  	/*
  	 * if we're fragmenting then we already have an id request, just return
  	 */
  	if (data->out_frag_pos)
  		return;
  
  	data->outbuf = wpabuf_alloc(sizeof(struct eap_pwd_id) +
  				    data->id_server_len);
  	if (data->outbuf == NULL) {
  		eap_pwd_state(data, FAILURE);
  		return;
  	}
  
  	if (os_get_random((u8 *) &data->token, sizeof(data->token)) < 0) {
  		wpabuf_free(data->outbuf);
  		data->outbuf = NULL;
  		eap_pwd_state(data, FAILURE);
  		return;
  	}
  
  	wpa_hexdump_key(MSG_DEBUG, "EAP-pwd (server): password",
  			data->password, data->password_len);
  	if (data->salt_len)
  		wpa_hexdump(MSG_DEBUG, "EAP-pwd (server): salt",
  			    data->salt, data->salt_len);
  
  	/*
  	 * If this is a salted password then figure out how it was hashed
  	 * based on the length.
  	 */
  	if (data->salt_len) {
  		switch (data->password_len) {
  		case 20:
  			data->password_prep = EAP_PWD_PREP_SSHA1;
  			break;
  		case 32:
  			data->password_prep = EAP_PWD_PREP_SSHA256;
  			break;
  		case 64:
  			data->password_prep = EAP_PWD_PREP_SSHA512;
  			break;
  		default:
  			wpa_printf(MSG_INFO,
  				   "EAP-pwd (server): bad size %d for salted password",
  				   (int) data->password_len);
  			eap_pwd_state(data, FAILURE);
  			return;
  		}
  	} else {
  		/* Otherwise, figure out whether it's MS hashed or plain */
  		data->password_prep = data->password_hash ? EAP_PWD_PREP_MS :
  			EAP_PWD_PREP_NONE;
  	}
  
  	wpabuf_put_be16(data->outbuf, data->group_num);
  	wpabuf_put_u8(data->outbuf, EAP_PWD_DEFAULT_RAND_FUNC);
  	wpabuf_put_u8(data->outbuf, EAP_PWD_DEFAULT_PRF);
  	wpabuf_put_data(data->outbuf, &data->token, sizeof(data->token));
  	wpabuf_put_u8(data->outbuf, data->password_prep);
  	wpabuf_put_data(data->outbuf, data->id_server, data->id_server_len);
  }
  
  
  static void eap_pwd_build_commit_req(struct eap_sm *sm,
  				     struct eap_pwd_data *data, u8 id)
  {
  	struct crypto_bignum *mask = NULL;
  	u8 *scalar, *element;
  	size_t prime_len, order_len;
  
  	wpa_printf(MSG_DEBUG, "EAP-pwd: Commit/Request");
  	/*
  	 * if we're fragmenting then we already have an commit request, just
  	 * return
  	 */
  	if (data->out_frag_pos)
  		return;
  
  	prime_len = crypto_ec_prime_len(data->grp->group);
  	order_len = crypto_ec_order_len(data->grp->group);
  
  	data->private_value = crypto_bignum_init();
  	data->my_element = crypto_ec_point_init(data->grp->group);
  	data->my_scalar = crypto_bignum_init();
  	mask = crypto_bignum_init();
  	if (!data->private_value || !data->my_element || !data->my_scalar ||
  	    !mask) {
  		wpa_printf(MSG_INFO, "EAP-PWD (server): scalar allocation "
  			   "fail");
  		goto fin;
  	}
  
  	if (eap_pwd_get_rand_mask(data->grp, data->private_value, mask,
  				  data->my_scalar) < 0)
  		goto fin;
  
  	if (crypto_ec_point_mul(data->grp->group, data->grp->pwe, mask,
  				data->my_element) < 0) {
  		wpa_printf(MSG_INFO, "EAP-PWD (server): element allocation "
  			   "fail");
  		eap_pwd_state(data, FAILURE);
  		goto fin;
  	}
  
  	if (crypto_ec_point_invert(data->grp->group, data->my_element) < 0) {
  		wpa_printf(MSG_INFO, "EAP-PWD (server): element inversion "
  			   "fail");
  		goto fin;
  	}
  
  	data->outbuf = wpabuf_alloc(2 * prime_len + order_len +
  				    (data->salt ? 1 + data->salt_len : 0));
  	if (data->outbuf == NULL)
  		goto fin;
  
  	/* If we're doing salted password prep, add the salt */
  	if (data->salt_len) {
  		wpabuf_put_u8(data->outbuf, data->salt_len);
  		wpabuf_put_data(data->outbuf, data->salt, data->salt_len);
  	}
  
  	/* We send the element as (x,y) followed by the scalar */
  	element = wpabuf_put(data->outbuf, 2 * prime_len);
  	scalar = wpabuf_put(data->outbuf, order_len);
  	crypto_bignum_to_bin(data->my_scalar, scalar, order_len, order_len);
  	if (crypto_ec_point_to_bin(data->grp->group, data->my_element, element,
  				   element + prime_len) < 0) {
  		wpa_printf(MSG_INFO, "EAP-PWD (server): point assignment "
  			   "fail");
  		goto fin;
  	}
  
  fin:
  	crypto_bignum_deinit(mask, 1);
  	if (data->outbuf == NULL)
  		eap_pwd_state(data, FAILURE);
  }
  
  
  static void eap_pwd_build_confirm_req(struct eap_sm *sm,
  				      struct eap_pwd_data *data, u8 id)
  {
  	struct crypto_hash *hash = NULL;
  	u8 conf[SHA256_MAC_LEN], *cruft = NULL, *ptr;
  	u16 grp;
  	size_t prime_len, order_len;
  
  	wpa_printf(MSG_DEBUG, "EAP-pwd: Confirm/Request");
  	/*
  	 * if we're fragmenting then we already have an confirm request, just
  	 * return
  	 */
  	if (data->out_frag_pos)
  		return;
  
  	prime_len = crypto_ec_prime_len(data->grp->group);
  	order_len = crypto_ec_order_len(data->grp->group);
  
  	/* Each component of the cruft will be at most as big as the prime */
  	cruft = os_malloc(prime_len * 2);
  	if (!cruft) {
  		wpa_printf(MSG_INFO, "EAP-PWD (server): debug allocation "
  			   "fail");
  		goto fin;
  	}
  
  	/*
  	 * commit is H(k | server_element | server_scalar | peer_element |
  	 *	       peer_scalar | ciphersuite)
  	 */
  	hash = eap_pwd_h_init();
  	if (hash == NULL)
  		goto fin;
  
  	/*
  	 * Zero the memory each time because this is mod prime math and some
  	 * value may start with a few zeros and the previous one did not.
  	 *
  	 * First is k
  	 */
  	crypto_bignum_to_bin(data->k, cruft, prime_len, prime_len);
  	eap_pwd_h_update(hash, cruft, prime_len);
  
  	/* server element: x, y */
  	if (crypto_ec_point_to_bin(data->grp->group, data->my_element, cruft,
  				   cruft + prime_len) < 0) {
  		wpa_printf(MSG_INFO, "EAP-PWD (server): confirm point "
  			   "assignment fail");
  		goto fin;
  	}
  	eap_pwd_h_update(hash, cruft, prime_len * 2);
  
  	/* server scalar */
  	crypto_bignum_to_bin(data->my_scalar, cruft, order_len, order_len);
  	eap_pwd_h_update(hash, cruft, order_len);
  
  	/* peer element: x, y */
  	if (crypto_ec_point_to_bin(data->grp->group, data->peer_element, cruft,
  				   cruft + prime_len) < 0) {
  		wpa_printf(MSG_INFO, "EAP-PWD (server): confirm point "
  			   "assignment fail");
  		goto fin;
  	}
  	eap_pwd_h_update(hash, cruft, prime_len * 2);
  
  	/* peer scalar */
  	crypto_bignum_to_bin(data->peer_scalar, cruft, order_len, order_len);
  	eap_pwd_h_update(hash, cruft, order_len);
  
  	/* ciphersuite */
  	grp = htons(data->group_num);
  	os_memset(cruft, 0, prime_len);
  	ptr = cruft;
  	os_memcpy(ptr, &grp, sizeof(u16));
  	ptr += sizeof(u16);
  	*ptr = EAP_PWD_DEFAULT_RAND_FUNC;
  	ptr += sizeof(u8);
  	*ptr = EAP_PWD_DEFAULT_PRF;
  	ptr += sizeof(u8);
  	eap_pwd_h_update(hash, cruft, ptr - cruft);
  
  	/* all done with the random function */
  	eap_pwd_h_final(hash, conf);
  	hash = NULL;
  	os_memcpy(data->my_confirm, conf, SHA256_MAC_LEN);
  
  	data->outbuf = wpabuf_alloc(SHA256_MAC_LEN);
  	if (data->outbuf == NULL)
  		goto fin;
  
  	wpabuf_put_data(data->outbuf, conf, SHA256_MAC_LEN);
  
  fin:
  	bin_clear_free(cruft, prime_len * 2);
  	if (data->outbuf == NULL)
  		eap_pwd_state(data, FAILURE);
  	eap_pwd_h_final(hash, NULL);
  }
  
  
  static struct wpabuf *
  eap_pwd_build_req(struct eap_sm *sm, void *priv, u8 id)
  {
  	struct eap_pwd_data *data = priv;
  	struct wpabuf *req;
  	u8 lm_exch;
  	const u8 *buf;
  	u16 totlen = 0;
  	size_t len;
  
  	/*
  	 * if we're buffering response fragments then just ACK
  	 */
  	if (data->in_frag_pos) {
  		wpa_printf(MSG_DEBUG, "EAP-pwd: ACKing a fragment!!");
  		req = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_PWD,
  				    EAP_PWD_HDR_SIZE, EAP_CODE_REQUEST, id);
  		if (req == NULL) {
  			eap_pwd_state(data, FAILURE);
  			return NULL;
  		}
  		switch (data->state) {
  		case PWD_ID_Req:
  			wpabuf_put_u8(req, EAP_PWD_OPCODE_ID_EXCH);
  			break;
  		case PWD_Commit_Req:
  			wpabuf_put_u8(req, EAP_PWD_OPCODE_COMMIT_EXCH);
  			break;
  		case PWD_Confirm_Req:
  			wpabuf_put_u8(req, EAP_PWD_OPCODE_CONFIRM_EXCH);
  			break;
  		default:
  			eap_pwd_state(data, FAILURE);   /* just to be sure */
  			wpabuf_free(req);
  			return NULL;
  		}
  		return req;
  	}
  
  	/*
  	 * build the data portion of a request
  	 */
  	switch (data->state) {
  	case PWD_ID_Req:
  		eap_pwd_build_id_req(sm, data, id);
  		lm_exch = EAP_PWD_OPCODE_ID_EXCH;
  		break;
  	case PWD_Commit_Req:
  		eap_pwd_build_commit_req(sm, data, id);
  		lm_exch = EAP_PWD_OPCODE_COMMIT_EXCH;
  		break;
  	case PWD_Confirm_Req:
  		eap_pwd_build_confirm_req(sm, data, id);
  		lm_exch = EAP_PWD_OPCODE_CONFIRM_EXCH;
  		break;
  	default:
  		wpa_printf(MSG_INFO, "EAP-pwd: Unknown state %d in build_req",
  			   data->state);
  		eap_pwd_state(data, FAILURE);
  		lm_exch = 0;    /* hush now, sweet compiler */
  		break;
  	}
  
  	if (data->state == FAILURE)
  		return NULL;
  
  	/*
  	 * determine whether that data needs to be fragmented
  	 */
  	len = wpabuf_len(data->outbuf) - data->out_frag_pos;
  	if ((len + EAP_PWD_HDR_SIZE) > data->mtu) {
  		len = data->mtu - EAP_PWD_HDR_SIZE;
  		EAP_PWD_SET_MORE_BIT(lm_exch);
  		/*
  		 * if this is the first fragment, need to set the M bit
  		 * and add the total length to the eap_pwd_hdr
  		 */
  		if (data->out_frag_pos == 0) {
  			EAP_PWD_SET_LENGTH_BIT(lm_exch);
  			totlen = wpabuf_len(data->outbuf) +
  				EAP_PWD_HDR_SIZE + sizeof(u16);
  			len -= sizeof(u16);
  			wpa_printf(MSG_DEBUG, "EAP-pwd: Fragmenting output, "
  				   "total length = %d", totlen);
  		}
  		wpa_printf(MSG_DEBUG, "EAP-pwd: Send a %d byte fragment",
  			   (int) len);
  	}
  
  	/*
  	 * alloc an eap request and populate it with the data
  	 */
  	req = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_PWD,
  			    EAP_PWD_HDR_SIZE + len +
  			    (totlen ? sizeof(u16) : 0),
  			    EAP_CODE_REQUEST, id);
  	if (req == NULL) {
  		eap_pwd_state(data, FAILURE);
  		return NULL;
  	}
  
  	wpabuf_put_u8(req, lm_exch);
  	if (EAP_PWD_GET_LENGTH_BIT(lm_exch))
  		wpabuf_put_be16(req, totlen);
  
  	buf = wpabuf_head_u8(data->outbuf);
  	wpabuf_put_data(req, buf + data->out_frag_pos, len);
  	data->out_frag_pos += len;
  	/*
  	 * either not fragged or last fragment, either way free up the data
  	 */
  	if (data->out_frag_pos >= wpabuf_len(data->outbuf)) {
  		wpabuf_free(data->outbuf);
  		data->outbuf = NULL;
  		data->out_frag_pos = 0;
  	}
  
  	return req;
  }
  
  
  static Boolean eap_pwd_check(struct eap_sm *sm, void *priv,
  			     struct wpabuf *respData)
  {
  	struct eap_pwd_data *data = priv;
  	const u8 *pos;
  	size_t len;
  
  	pos = eap_hdr_validate(EAP_VENDOR_IETF, EAP_TYPE_PWD, respData, &len);
  	if (pos == NULL || len < 1) {
  		wpa_printf(MSG_INFO, "EAP-pwd: Invalid frame");
  		return TRUE;
  	}
  
  	wpa_printf(MSG_DEBUG, "EAP-pwd: Received frame: exch = %d, len = %d",
  		   EAP_PWD_GET_EXCHANGE(*pos), (int) len);
  
  	if (data->state == PWD_ID_Req &&
  	    ((EAP_PWD_GET_EXCHANGE(*pos)) == EAP_PWD_OPCODE_ID_EXCH))
  		return FALSE;
  
  	if (data->state == PWD_Commit_Req &&
  	    ((EAP_PWD_GET_EXCHANGE(*pos)) == EAP_PWD_OPCODE_COMMIT_EXCH))
  		return FALSE;
  
  	if (data->state == PWD_Confirm_Req &&
  	    ((EAP_PWD_GET_EXCHANGE(*pos)) == EAP_PWD_OPCODE_CONFIRM_EXCH))
  		return FALSE;
  
  	wpa_printf(MSG_INFO, "EAP-pwd: Unexpected opcode=%d in state=%d",
  		   *pos, data->state);
  
  	return TRUE;
  }
  
  
  static void eap_pwd_process_id_resp(struct eap_sm *sm,
  				    struct eap_pwd_data *data,
  				    const u8 *payload, size_t payload_len)
  {
  	struct eap_pwd_id *id;
  	const u8 *password;
  	size_t password_len;
  	u8 pwhashhash[16];
  	int res;
  
  	if (payload_len < sizeof(struct eap_pwd_id)) {
  		wpa_printf(MSG_INFO, "EAP-pwd: Invalid ID response");
  		return;
  	}
  
  	id = (struct eap_pwd_id *) payload;
  	if ((data->group_num != be_to_host16(id->group_num)) ||
  	    (id->random_function != EAP_PWD_DEFAULT_RAND_FUNC) ||
  	    (os_memcmp(id->token, (u8 *)&data->token, sizeof(data->token))) ||
  	    (id->prf != EAP_PWD_DEFAULT_PRF) ||
  	    (id->prep != data->password_prep)) {
  		wpa_printf(MSG_INFO, "EAP-pwd: peer changed parameters");
  		eap_pwd_state(data, FAILURE);
  		return;
  	}
  	if (data->id_peer || data->grp) {
  		wpa_printf(MSG_INFO, "EAP-pwd: data was already allocated");
  		return;
  	}
  	data->id_peer = os_malloc(payload_len - sizeof(struct eap_pwd_id));
  	if (data->id_peer == NULL) {
  		wpa_printf(MSG_INFO, "EAP-PWD: memory allocation id fail");
  		return;
  	}
  	data->id_peer_len = payload_len - sizeof(struct eap_pwd_id);
  	os_memcpy(data->id_peer, id->identity, data->id_peer_len);
  	wpa_hexdump_ascii(MSG_DEBUG, "EAP-PWD (server): peer sent id of",
  			  data->id_peer, data->id_peer_len);
  
  	data->grp = get_eap_pwd_group(data->group_num);
  	if (data->grp == NULL) {
  		wpa_printf(MSG_INFO, "EAP-PWD: failed to allocate memory for "
  			   "group");
  		return;
  	}
  
  	/*
  	 * If it's PREP_MS then hash the password again, otherwise regardless
  	 * of the prep the client is doing, the password we have is the one to
  	 * use to generate the password element.
  	 */
  	if (data->password_prep == EAP_PWD_PREP_MS) {
  		res = hash_nt_password_hash(data->password, pwhashhash);
  		if (res)
  			return;
  		password = pwhashhash;
  		password_len = sizeof(pwhashhash);
  	} else {
  		password = data->password;
  		password_len = data->password_len;
  	}
  
  	res = compute_password_element(data->grp, data->group_num,
  				       password, password_len,
  				       data->id_server, data->id_server_len,
  				       data->id_peer, data->id_peer_len,
  				       (u8 *) &data->token);
  	forced_memzero(pwhashhash, sizeof(pwhashhash));
  	if (res) {
  		wpa_printf(MSG_INFO, "EAP-PWD (server): unable to compute "
  			   "PWE");
  		return;
  	}
  	wpa_printf(MSG_DEBUG, "EAP-PWD (server): computed %d bit PWE...",
  		   (int) crypto_ec_prime_len_bits(data->grp->group));
  
  	eap_pwd_state(data, PWD_Commit_Req);
  }
  
  
  static void
  eap_pwd_process_commit_resp(struct eap_sm *sm, struct eap_pwd_data *data,
  			    const u8 *payload, size_t payload_len)
  {
  	const u8 *ptr;
  	struct crypto_ec_point *K = NULL;
  	int res = 0;
  	size_t prime_len, order_len;
  
  	wpa_printf(MSG_DEBUG, "EAP-pwd: Received commit response");
  
  	prime_len = crypto_ec_prime_len(data->grp->group);
  	order_len = crypto_ec_order_len(data->grp->group);
  
  	if (payload_len != 2 * prime_len + order_len) {
  		wpa_printf(MSG_INFO,
  			   "EAP-pwd: Unexpected Commit payload length %u (expected %u)",
  			   (unsigned int) payload_len,
  			   (unsigned int) (2 * prime_len + order_len));
  		goto fin;
  	}
  
  	data->k = crypto_bignum_init();
  	K = crypto_ec_point_init(data->grp->group);
  	if (!data->k || !K) {
  		wpa_printf(MSG_INFO, "EAP-PWD (server): peer data allocation "
  			   "fail");
  		goto fin;
  	}
  
  	/* element, x then y, followed by scalar */
  	ptr = payload;
  	data->peer_element = eap_pwd_get_element(data->grp, ptr);
  	if (!data->peer_element) {
  		wpa_printf(MSG_INFO, "EAP-PWD (server): setting peer element "
  			   "fail");
  		goto fin;
  	}
  	ptr += prime_len * 2;
  	data->peer_scalar = eap_pwd_get_scalar(data->grp, ptr);
  	if (!data->peer_scalar) {
  		wpa_printf(MSG_INFO, "EAP-PWD (server): peer data allocation "
  			   "fail");
  		goto fin;
  	}
  
  	/* detect reflection attacks */
  	if (crypto_bignum_cmp(data->my_scalar, data->peer_scalar) == 0 ||
  	    crypto_ec_point_cmp(data->grp->group, data->my_element,
  				data->peer_element) == 0) {
  		wpa_printf(MSG_INFO,
  			   "EAP-PWD (server): detected reflection attack!");
  		goto fin;
  	}
  
  	/* compute the shared key, k */
  	if ((crypto_ec_point_mul(data->grp->group, data->grp->pwe,
  				 data->peer_scalar, K) < 0) ||
  	    (crypto_ec_point_add(data->grp->group, K, data->peer_element,
  				 K) < 0) ||
  	    (crypto_ec_point_mul(data->grp->group, K, data->private_value,
  				 K) < 0)) {
  		wpa_printf(MSG_INFO, "EAP-PWD (server): computing shared key "
  			   "fail");
  		goto fin;
  	}
  
  	/*
  	 * This check is strictly speaking just for the case where
  	 * co-factor > 1 but it was suggested that even though this is probably
  	 * never going to happen it is a simple and safe check "just to be
  	 * sure" so let's be safe.
  	 */
  	if (crypto_ec_point_is_at_infinity(data->grp->group, K)) {
  		wpa_printf(MSG_INFO, "EAP-PWD (server): shared key point is "
  			   "at infinity");
  		goto fin;
  	}
  	if (crypto_ec_point_x(data->grp->group, K, data->k)) {
  		wpa_printf(MSG_INFO, "EAP-PWD (server): unable to extract "
  			   "shared secret from secret point");
  		goto fin;
  	}
  	res = 1;
  
  fin:
  	crypto_ec_point_deinit(K, 1);
  
  	if (res)
  		eap_pwd_state(data, PWD_Confirm_Req);
  	else
  		eap_pwd_state(data, FAILURE);
  }
  
  
  static void
  eap_pwd_process_confirm_resp(struct eap_sm *sm, struct eap_pwd_data *data,
  			     const u8 *payload, size_t payload_len)
  {
  	struct crypto_hash *hash = NULL;
  	u32 cs;
  	u16 grp;
  	u8 conf[SHA256_MAC_LEN], *cruft = NULL, *ptr;
  	size_t prime_len, order_len;
  
  	prime_len = crypto_ec_prime_len(data->grp->group);
  	order_len = crypto_ec_order_len(data->grp->group);
  
  	if (payload_len != SHA256_MAC_LEN) {
  		wpa_printf(MSG_INFO,
  			   "EAP-pwd: Unexpected Confirm payload length %u (expected %u)",
  			   (unsigned int) payload_len, SHA256_MAC_LEN);
  		goto fin;
  	}
  
  	/* build up the ciphersuite: group | random_function | prf */
  	grp = htons(data->group_num);
  	ptr = (u8 *) &cs;
  	os_memcpy(ptr, &grp, sizeof(u16));
  	ptr += sizeof(u16);
  	*ptr = EAP_PWD_DEFAULT_RAND_FUNC;
  	ptr += sizeof(u8);
  	*ptr = EAP_PWD_DEFAULT_PRF;
  
  	/* each component of the cruft will be at most as big as the prime */
  	cruft = os_malloc(prime_len * 2);
  	if (!cruft) {
  		wpa_printf(MSG_INFO, "EAP-PWD (peer): allocation fail");
  		goto fin;
  	}
  
  	/*
  	 * commit is H(k | peer_element | peer_scalar | server_element |
  	 *	       server_scalar | ciphersuite)
  	 */
  	hash = eap_pwd_h_init();
  	if (hash == NULL)
  		goto fin;
  
  	/* k */
  	crypto_bignum_to_bin(data->k, cruft, prime_len, prime_len);
  	eap_pwd_h_update(hash, cruft, prime_len);
  
  	/* peer element: x, y */
  	if (crypto_ec_point_to_bin(data->grp->group, data->peer_element, cruft,
  				   cruft + prime_len) < 0) {
  		wpa_printf(MSG_INFO, "EAP-PWD (server): confirm point "
  			   "assignment fail");
  		goto fin;
  	}
  	eap_pwd_h_update(hash, cruft, prime_len * 2);
  
  	/* peer scalar */
  	crypto_bignum_to_bin(data->peer_scalar, cruft, order_len, order_len);
  	eap_pwd_h_update(hash, cruft, order_len);
  
  	/* server element: x, y */
  	if (crypto_ec_point_to_bin(data->grp->group, data->my_element, cruft,
  				   cruft + prime_len) < 0) {
  		wpa_printf(MSG_INFO, "EAP-PWD (server): confirm point "
  			   "assignment fail");
  		goto fin;
  	}
  	eap_pwd_h_update(hash, cruft, prime_len * 2);
  
  	/* server scalar */
  	crypto_bignum_to_bin(data->my_scalar, cruft, order_len, order_len);
  	eap_pwd_h_update(hash, cruft, order_len);
  
  	/* ciphersuite */
  	eap_pwd_h_update(hash, (u8 *) &cs, sizeof(u32));
  
  	/* all done */
  	eap_pwd_h_final(hash, conf);
  	hash = NULL;
  
  	ptr = (u8 *) payload;
  	if (os_memcmp_const(conf, ptr, SHA256_MAC_LEN)) {
  		wpa_printf(MSG_INFO, "EAP-PWD (server): confirm did not "
  			   "verify");
  		goto fin;
  	}
  
  	wpa_printf(MSG_DEBUG, "EAP-pwd (server): confirm verified");
  	if (compute_keys(data->grp, data->k,
  			 data->peer_scalar, data->my_scalar, conf,
  			 data->my_confirm, &cs, data->msk, data->emsk,
  			 data->session_id) < 0)
  		eap_pwd_state(data, FAILURE);
  	else
  		eap_pwd_state(data, SUCCESS);
  
  fin:
  	bin_clear_free(cruft, prime_len * 2);
  	eap_pwd_h_final(hash, NULL);
  }
  
  
  static void eap_pwd_process(struct eap_sm *sm, void *priv,
  			    struct wpabuf *respData)
  {
  	struct eap_pwd_data *data = priv;
  	const u8 *pos;
  	size_t len;
  	u8 lm_exch;
  	u16 tot_len;
  
  	pos = eap_hdr_validate(EAP_VENDOR_IETF, EAP_TYPE_PWD, respData, &len);
  	if ((pos == NULL) || (len < 1)) {
  		wpa_printf(MSG_INFO, "Bad EAP header! pos %s and len = %d",
  			   (pos == NULL) ? "is NULL" : "is not NULL",
  			   (int) len);
  		return;
  	}
  
  	lm_exch = *pos;
  	pos++;            /* skip over the bits and the exch */
  	len--;
  
  	/*
  	 * if we're fragmenting then this should be an ACK with no data,
  	 * just return and continue fragmenting in the "build" section above
  	 */
  	if (data->out_frag_pos) {
  		if (len > 1)
  			wpa_printf(MSG_INFO, "EAP-pwd: Bad response! "
  				   "Fragmenting but not an ACK");
  		else
  			wpa_printf(MSG_DEBUG, "EAP-pwd: received ACK from "
  				   "peer");
  		return;
  	}
  	/*
  	 * if we're receiving fragmented packets then we need to buffer...
  	 *
  	 * the first fragment has a total length
  	 */
  	if (EAP_PWD_GET_LENGTH_BIT(lm_exch)) {
  		if (len < 2) {
  			wpa_printf(MSG_DEBUG,
  				   "EAP-pwd: Frame too short to contain Total-Length field");
  			return;
  		}
  		tot_len = WPA_GET_BE16(pos);
  		wpa_printf(MSG_DEBUG, "EAP-pwd: Incoming fragments, total "
  			   "length = %d", tot_len);
  		if (tot_len > 15000)
  			return;
  		if (data->inbuf) {
  			wpa_printf(MSG_DEBUG,
  				   "EAP-pwd: Unexpected new fragment start when previous fragment is still in use");
  			return;
  		}
  		data->inbuf = wpabuf_alloc(tot_len);
  		if (data->inbuf == NULL) {
  			wpa_printf(MSG_INFO, "EAP-pwd: Out of memory to "
  				   "buffer fragments!");
  			return;
  		}
  		data->in_frag_pos = 0;
  		pos += sizeof(u16);
  		len -= sizeof(u16);
  	}
  	/*
  	 * the first and all intermediate fragments have the M bit set
  	 */
  	if (EAP_PWD_GET_MORE_BIT(lm_exch) || data->in_frag_pos) {
  		if (!data->inbuf) {
  			wpa_printf(MSG_DEBUG,
  				   "EAP-pwd: No buffer for reassembly");
  			eap_pwd_state(data, FAILURE);
  			return;
  		}
  		if ((data->in_frag_pos + len) > wpabuf_size(data->inbuf)) {
  			wpa_printf(MSG_DEBUG, "EAP-pwd: Buffer overflow "
  				   "attack detected! (%d+%d > %d)",
  				   (int) data->in_frag_pos, (int) len,
  				   (int) wpabuf_size(data->inbuf));
  			eap_pwd_state(data, FAILURE);
  			return;
  		}
  		wpabuf_put_data(data->inbuf, pos, len);
  		data->in_frag_pos += len;
  	}
  	if (EAP_PWD_GET_MORE_BIT(lm_exch)) {
  		wpa_printf(MSG_DEBUG, "EAP-pwd: Got a %d byte fragment",
  			   (int) len);
  		return;
  	}
  	/*
  	 * last fragment won't have the M bit set (but we're obviously
  	 * buffering fragments so that's how we know it's the last)
  	 */
  	if (data->in_frag_pos && data->inbuf) {
  		pos = wpabuf_head_u8(data->inbuf);
  		len = data->in_frag_pos;
  		wpa_printf(MSG_DEBUG, "EAP-pwd: Last fragment, %d bytes",
  			   (int) len);
  	}
  	switch (EAP_PWD_GET_EXCHANGE(lm_exch)) {
  	case EAP_PWD_OPCODE_ID_EXCH:
  		eap_pwd_process_id_resp(sm, data, pos, len);
  		break;
  	case EAP_PWD_OPCODE_COMMIT_EXCH:
  		eap_pwd_process_commit_resp(sm, data, pos, len);
  		break;
  	case EAP_PWD_OPCODE_CONFIRM_EXCH:
  		eap_pwd_process_confirm_resp(sm, data, pos, len);
  		break;
  	}
  	/*
  	 * if we had been buffering fragments, here's a great place
  	 * to clean up
  	 */
  	if (data->in_frag_pos) {
  		wpabuf_free(data->inbuf);
  		data->inbuf = NULL;
  		data->in_frag_pos = 0;
  	}
  }
  
  
  static u8 * eap_pwd_getkey(struct eap_sm *sm, void *priv, size_t *len)
  {
  	struct eap_pwd_data *data = priv;
  	u8 *key;
  
  	if (data->state != SUCCESS)
  		return NULL;
  
  	key = os_memdup(data->msk, EAP_MSK_LEN);
  	if (key == NULL)
  		return NULL;
  
  	*len = EAP_MSK_LEN;
  
  	return key;
  }
  
  
  static u8 * eap_pwd_get_emsk(struct eap_sm *sm, void *priv, size_t *len)
  {
  	struct eap_pwd_data *data = priv;
  	u8 *key;
  
  	if (data->state != SUCCESS)
  		return NULL;
  
  	key = os_memdup(data->emsk, EAP_EMSK_LEN);
  	if (key == NULL)
  		return NULL;
  
  	*len = EAP_EMSK_LEN;
  
  	return key;
  }
  
  
  static Boolean eap_pwd_is_success(struct eap_sm *sm, void *priv)
  {
  	struct eap_pwd_data *data = priv;
  	return data->state == SUCCESS;
  }
  
  
  static Boolean eap_pwd_is_done(struct eap_sm *sm, void *priv)
  {
  	struct eap_pwd_data *data = priv;
  	return (data->state == SUCCESS) || (data->state == FAILURE);
  }
  
  
  static u8 * eap_pwd_get_session_id(struct eap_sm *sm, void *priv, size_t *len)
  {
  	struct eap_pwd_data *data = priv;
  	u8 *id;
  
  	if (data->state != SUCCESS)
  		return NULL;
  
  	id = os_memdup(data->session_id, 1 + SHA256_MAC_LEN);
  	if (id == NULL)
  		return NULL;
  
  	*len = 1 + SHA256_MAC_LEN;
  
  	return id;
  }
  
  
  int eap_server_pwd_register(void)
  {
  	struct eap_method *eap;
  
  	eap = eap_server_method_alloc(EAP_SERVER_METHOD_INTERFACE_VERSION,
  				      EAP_VENDOR_IETF, EAP_TYPE_PWD,
  				      "PWD");
  	if (eap == NULL)
  		return -1;
  
  	eap->init = eap_pwd_init;
  	eap->reset = eap_pwd_reset;
  	eap->buildReq = eap_pwd_build_req;
  	eap->check = eap_pwd_check;
  	eap->process = eap_pwd_process;
  	eap->isDone = eap_pwd_is_done;
  	eap->getKey = eap_pwd_getkey;
  	eap->get_emsk = eap_pwd_get_emsk;
  	eap->isSuccess = eap_pwd_is_success;
  	eap->getSessionId = eap_pwd_get_session_id;
  
  	return eap_server_method_register(eap);
  }
  