text: /*
   * EAP-IKEv2 server (RFC 5106)
   * Copyright (c) 2007, 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 "eap_i.h"
  #include "eap_common/eap_ikev2_common.h"
  #include "ikev2.h"
  
  
  struct eap_ikev2_data {
  	struct ikev2_initiator_data ikev2;
  	enum { MSG, FRAG_ACK, WAIT_FRAG_ACK, DONE, FAIL } state;
  	struct wpabuf *in_buf;
  	struct wpabuf *out_buf;
  	size_t out_used;
  	size_t fragment_size;
  	int keys_ready;
  	u8 keymat[EAP_MSK_LEN + EAP_EMSK_LEN];
  	int keymat_ok;
  };
  
  
  static const u8 * eap_ikev2_get_shared_secret(void *ctx, const u8 *IDr,
  					      size_t IDr_len,
  					      size_t *secret_len)
  {
  	struct eap_sm *sm = ctx;
  
  	if (IDr == NULL) {
  		wpa_printf(MSG_DEBUG, "EAP-IKEV2: No IDr received - default "
  			   "to user identity from EAP-Identity");
  		IDr = sm->identity;
  		IDr_len = sm->identity_len;
  	}
  
  	if (eap_user_get(sm, IDr, IDr_len, 0) < 0 || sm->user == NULL ||
  	    sm->user->password == NULL) {
  		wpa_printf(MSG_DEBUG, "EAP-IKEV2: No user entry found");
  		return NULL;
  	}
  
  	*secret_len = sm->user->password_len;
  	return sm->user->password;
  }
  
  
  static const char * eap_ikev2_state_txt(int state)
  {
  	switch (state) {
  	case MSG:
  		return "MSG";
  	case FRAG_ACK:
  		return "FRAG_ACK";
  	case WAIT_FRAG_ACK:
  		return "WAIT_FRAG_ACK";
  	case DONE:
  		return "DONE";
  	case FAIL:
  		return "FAIL";
  	default:
  		return "?";
  	}
  }
  
  
  static void eap_ikev2_state(struct eap_ikev2_data *data, int state)
  {
  	wpa_printf(MSG_DEBUG, "EAP-IKEV2: %s -> %s",
  		   eap_ikev2_state_txt(data->state),
  		   eap_ikev2_state_txt(state));
  	data->state = state;
  }
  
  
  static void * eap_ikev2_init(struct eap_sm *sm)
  {
  	struct eap_ikev2_data *data;
  
  	data = os_zalloc(sizeof(*data));
  	if (data == NULL)
  		return NULL;
  	data->state = MSG;
  	data->fragment_size = IKEV2_FRAGMENT_SIZE;
  	data->ikev2.state = SA_INIT;
  	data->ikev2.peer_auth = PEER_AUTH_SECRET;
  	data->ikev2.key_pad = (u8 *) os_strdup("Key Pad for EAP-IKEv2");
  	if (data->ikev2.key_pad == NULL)
  		goto failed;
  	data->ikev2.key_pad_len = 21;
  
  	/* TODO: make proposals configurable */
  	data->ikev2.proposal.proposal_num = 1;
  	data->ikev2.proposal.integ = AUTH_HMAC_SHA1_96;
  	data->ikev2.proposal.prf = PRF_HMAC_SHA1;
  	data->ikev2.proposal.encr = ENCR_AES_CBC;
  	data->ikev2.proposal.dh = DH_GROUP2_1024BIT_MODP;
  
  	data->ikev2.IDi = (u8 *) os_strdup("hostapd");
  	data->ikev2.IDi_len = 7;
  
  	data->ikev2.get_shared_secret = eap_ikev2_get_shared_secret;
  	data->ikev2.cb_ctx = sm;
  
  	return data;
  
  failed:
  	ikev2_initiator_deinit(&data->ikev2);
  	os_free(data);
  	return NULL;
  }
  
  
  static void eap_ikev2_reset(struct eap_sm *sm, void *priv)
  {
  	struct eap_ikev2_data *data = priv;
  	wpabuf_free(data->in_buf);
  	wpabuf_free(data->out_buf);
  	ikev2_initiator_deinit(&data->ikev2);
  	os_free(data);
  }
  
  
  static struct wpabuf * eap_ikev2_build_msg(struct eap_ikev2_data *data, u8 id)
  {
  	struct wpabuf *req;
  	u8 flags;
  	size_t send_len, plen, icv_len = 0;
  
  	wpa_printf(MSG_DEBUG, "EAP-IKEV2: Generating Request");
  
  	flags = 0;
  	send_len = wpabuf_len(data->out_buf) - data->out_used;
  	if (1 + send_len > data->fragment_size) {
  		send_len = data->fragment_size - 1;
  		flags |= IKEV2_FLAGS_MORE_FRAGMENTS;
  		if (data->out_used == 0) {
  			flags |= IKEV2_FLAGS_LENGTH_INCLUDED;
  			send_len -= 4;
  		}
  	}
  
  	plen = 1 + send_len;
  	if (flags & IKEV2_FLAGS_LENGTH_INCLUDED)
  		plen += 4;
  	if (data->keys_ready) {
  		const struct ikev2_integ_alg *integ;
  		wpa_printf(MSG_DEBUG, "EAP-IKEV2: Add Integrity Checksum "
  			   "Data");
  		flags |= IKEV2_FLAGS_ICV_INCLUDED;
  		integ = ikev2_get_integ(data->ikev2.proposal.integ);
  		if (integ == NULL) {
  			wpa_printf(MSG_DEBUG, "EAP-IKEV2: Unknown INTEG "
  				   "transform / cannot generate ICV");
  			return NULL;
  		}
  		icv_len = integ->hash_len;
  
  		plen += icv_len;
  	}
  	req = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_IKEV2, plen,
  			    EAP_CODE_REQUEST, id);
  	if (req == NULL)
  		return NULL;
  
  	wpabuf_put_u8(req, flags); /* Flags */
  	if (flags & IKEV2_FLAGS_LENGTH_INCLUDED)
  		wpabuf_put_be32(req, wpabuf_len(data->out_buf));
  
  	wpabuf_put_data(req, wpabuf_head_u8(data->out_buf) + data->out_used,
  			send_len);
  	data->out_used += send_len;
  
  	if (flags & IKEV2_FLAGS_ICV_INCLUDED) {
  		const u8 *msg = wpabuf_head(req);
  		size_t len = wpabuf_len(req);
  		ikev2_integ_hash(data->ikev2.proposal.integ,
  				 data->ikev2.keys.SK_ai,
  				 data->ikev2.keys.SK_integ_len,
  				 msg, len, wpabuf_put(req, icv_len));
  	}
  
  	if (data->out_used == wpabuf_len(data->out_buf)) {
  		wpa_printf(MSG_DEBUG, "EAP-IKEV2: Sending out %lu bytes "
  			   "(message sent completely)",
  			   (unsigned long) send_len);
  		wpabuf_free(data->out_buf);
  		data->out_buf = NULL;
  		data->out_used = 0;
  	} else {
  		wpa_printf(MSG_DEBUG, "EAP-IKEV2: Sending out %lu bytes "
  			   "(%lu more to send)", (unsigned long) send_len,
  			   (unsigned long) wpabuf_len(data->out_buf) -
  			   data->out_used);
  		eap_ikev2_state(data, WAIT_FRAG_ACK);
  	}
  
  	return req;
  }
  
  
  static struct wpabuf * eap_ikev2_buildReq(struct eap_sm *sm, void *priv, u8 id)
  {
  	struct eap_ikev2_data *data = priv;
  
  	switch (data->state) {
  	case MSG:
  		if (data->out_buf == NULL) {
  			data->out_buf = ikev2_initiator_build(&data->ikev2);
  			if (data->out_buf == NULL) {
  				wpa_printf(MSG_DEBUG, "EAP-IKEV2: Failed to "
  					   "generate IKEv2 message");
  				return NULL;
  			}
  			data->out_used = 0;
  		}
  		/* pass through */
  	case WAIT_FRAG_ACK:
  		return eap_ikev2_build_msg(data, id);
  	case FRAG_ACK:
  		return eap_ikev2_build_frag_ack(id, EAP_CODE_REQUEST);
  	default:
  		wpa_printf(MSG_DEBUG, "EAP-IKEV2: Unexpected state %d in "
  			   "buildReq", data->state);
  		return NULL;
  	}
  }
  
  
  static Boolean eap_ikev2_check(struct eap_sm *sm, void *priv,
  			       struct wpabuf *respData)
  {
  	const u8 *pos;
  	size_t len;
  
  	pos = eap_hdr_validate(EAP_VENDOR_IETF, EAP_TYPE_IKEV2, respData,
  			       &len);
  	if (pos == NULL) {
  		wpa_printf(MSG_INFO, "EAP-IKEV2: Invalid frame");
  		return TRUE;
  	}
  
  	return FALSE;
  }
  
  
  static int eap_ikev2_process_icv(struct eap_ikev2_data *data,
  				 const struct wpabuf *respData,
  				 u8 flags, const u8 *pos, const u8 **end)
  {
  	if (flags & IKEV2_FLAGS_ICV_INCLUDED) {
  		int icv_len = eap_ikev2_validate_icv(
  			data->ikev2.proposal.integ, &data->ikev2.keys, 0,
  			respData, pos, *end);
  		if (icv_len < 0)
  			return -1;
  		/* Hide Integrity Checksum Data from further processing */
  		*end -= icv_len;
  	} else if (data->keys_ready) {
  		wpa_printf(MSG_INFO, "EAP-IKEV2: The message should have "
  			   "included integrity checksum");
  		return -1;
  	}
  
  	return 0;
  }
  
  
  static int eap_ikev2_process_cont(struct eap_ikev2_data *data,
  				  const u8 *buf, size_t len)
  {
  	/* Process continuation of a pending message */
  	if (len > wpabuf_tailroom(data->in_buf)) {
  		wpa_printf(MSG_DEBUG, "EAP-IKEV2: Fragment overflow");
  		eap_ikev2_state(data, FAIL);
  		return -1;
  	}
  
  	wpabuf_put_data(data->in_buf, buf, len);
  	wpa_printf(MSG_DEBUG, "EAP-IKEV2: Received %lu bytes, waiting for %lu "
  		   "bytes more", (unsigned long) len,
  		   (unsigned long) wpabuf_tailroom(data->in_buf));
  
  	return 0;
  }
  
  
  static int eap_ikev2_process_fragment(struct eap_ikev2_data *data,
  				      u8 flags, u32 message_length,
  				      const u8 *buf, size_t len)
  {
  	/* Process a fragment that is not the last one of the message */
  	if (data->in_buf == NULL && !(flags & IKEV2_FLAGS_LENGTH_INCLUDED)) {
  		wpa_printf(MSG_DEBUG, "EAP-IKEV2: No Message Length field in "
  			   "a fragmented packet");
  		return -1;
  	}
  
  	if (data->in_buf == NULL) {
  		/* First fragment of the message */
  		data->in_buf = wpabuf_alloc(message_length);
  		if (data->in_buf == NULL) {
  			wpa_printf(MSG_DEBUG, "EAP-IKEV2: No memory for "
  				   "message");
  			return -1;
  		}
  		wpabuf_put_data(data->in_buf, buf, len);
  		wpa_printf(MSG_DEBUG, "EAP-IKEV2: Received %lu bytes in first "
  			   "fragment, waiting for %lu bytes more",
  			   (unsigned long) len,
  			   (unsigned long) wpabuf_tailroom(data->in_buf));
  	}
  
  	return 0;
  }
  
  
  static int eap_ikev2_server_keymat(struct eap_ikev2_data *data)
  {
  	if (eap_ikev2_derive_keymat(
  		    data->ikev2.proposal.prf, &data->ikev2.keys,
  		    data->ikev2.i_nonce, data->ikev2.i_nonce_len,
  		    data->ikev2.r_nonce, data->ikev2.r_nonce_len,
  		    data->keymat) < 0) {
  		wpa_printf(MSG_DEBUG, "EAP-IKEV2: Failed to derive "
  			   "key material");
  		return -1;
  	}
  	data->keymat_ok = 1;
  	return 0;
  }
  
  
  static void eap_ikev2_process(struct eap_sm *sm, void *priv,
  			      struct wpabuf *respData)
  {
  	struct eap_ikev2_data *data = priv;
  	const u8 *start, *pos, *end;
  	size_t len;
  	u8 flags;
  	u32 message_length = 0;
  	struct wpabuf tmpbuf;
  
  	pos = eap_hdr_validate(EAP_VENDOR_IETF, EAP_TYPE_IKEV2, respData,
  			       &len);
  	if (pos == NULL)
  		return; /* Should not happen; message already verified */
  
  	start = pos;
  	end = start + len;
  
  	if (len == 0) {
  		/* fragment ack */
  		flags = 0;
  	} else
  		flags = *pos++;
  
  	if (eap_ikev2_process_icv(data, respData, flags, pos, &end) < 0) {
  		eap_ikev2_state(data, FAIL);
  		return;
  	}
  
  	if (flags & IKEV2_FLAGS_LENGTH_INCLUDED) {
  		if (end - pos < 4) {
  			wpa_printf(MSG_DEBUG, "EAP-IKEV2: Message underflow");
  			eap_ikev2_state(data, FAIL);
  			return;
  		}
  		message_length = WPA_GET_BE32(pos);
  		pos += 4;
  
  		if (message_length < (u32) (end - pos)) {
  			wpa_printf(MSG_DEBUG, "EAP-IKEV2: Invalid Message "
  				   "Length (%d; %ld remaining in this msg)",
  				   message_length, (long) (end - pos));
  			eap_ikev2_state(data, FAIL);
  			return;
  		}
  	}
  	wpa_printf(MSG_DEBUG, "EAP-IKEV2: Received packet: Flags 0x%x "
  		   "Message Length %u", flags, message_length);
  
  	if (data->state == WAIT_FRAG_ACK) {
  		if (len != 0) {
  			wpa_printf(MSG_DEBUG, "EAP-IKEV2: Unexpected payload "
  				   "in WAIT_FRAG_ACK state");
  			eap_ikev2_state(data, FAIL);
  			return;
  		}
  		wpa_printf(MSG_DEBUG, "EAP-IKEV2: Fragment acknowledged");
  		eap_ikev2_state(data, MSG);
  		return;
  	}
  
  	if (data->in_buf && eap_ikev2_process_cont(data, pos, end - pos) < 0) {
  		eap_ikev2_state(data, FAIL);
  		return;
  	}
  		
  	if (flags & IKEV2_FLAGS_MORE_FRAGMENTS) {
  		if (eap_ikev2_process_fragment(data, flags, message_length,
  					       pos, end - pos) < 0)
  			eap_ikev2_state(data, FAIL);
  		else
  			eap_ikev2_state(data, FRAG_ACK);
  		return;
  	} else if (data->state == FRAG_ACK) {
  		wpa_printf(MSG_DEBUG, "EAP-TNC: All fragments received");
  		data->state = MSG;
  	}
  
  	if (data->in_buf == NULL) {
  		/* Wrap unfragmented messages as wpabuf without extra copy */
  		wpabuf_set(&tmpbuf, pos, end - pos);
  		data->in_buf = &tmpbuf;
  	}
  
  	if (ikev2_initiator_process(&data->ikev2, data->in_buf) < 0) {
  		if (data->in_buf == &tmpbuf)
  			data->in_buf = NULL;
  		eap_ikev2_state(data, FAIL);
  		return;
  	}
  
  	switch (data->ikev2.state) {
  	case SA_AUTH:
  		/* SA_INIT was sent out, so message have to be
  		 * integrity protected from now on. */
  		data->keys_ready = 1;
  		break;
  	case IKEV2_DONE:
  		if (data->state == FAIL)
  			break;
  		wpa_printf(MSG_DEBUG, "EAP-IKEV2: Authentication completed "
  			   "successfully");
  		if (eap_ikev2_server_keymat(data))
  			break;
  		eap_ikev2_state(data, DONE);
  		break;
  	default:
  		break;
  	}
  
  	if (data->in_buf != &tmpbuf)
  		wpabuf_free(data->in_buf);
  	data->in_buf = NULL;
  }
  
  
  static Boolean eap_ikev2_isDone(struct eap_sm *sm, void *priv)
  {
  	struct eap_ikev2_data *data = priv;
  	return data->state == DONE || data->state == FAIL;
  }
  
  
  static Boolean eap_ikev2_isSuccess(struct eap_sm *sm, void *priv)
  {
  	struct eap_ikev2_data *data = priv;
  	return data->state == DONE && data->ikev2.state == IKEV2_DONE &&
  		data->keymat_ok;
  }
  
  
  static u8 * eap_ikev2_getKey(struct eap_sm *sm, void *priv, size_t *len)
  {
  	struct eap_ikev2_data *data = priv;
  	u8 *key;
  
  	if (data->state != DONE || !data->keymat_ok)
  		return NULL;
  
  	key = os_malloc(EAP_MSK_LEN);
  	if (key) {
  		os_memcpy(key, data->keymat, EAP_MSK_LEN);
  		*len = EAP_MSK_LEN;
  	}
  
  	return key;
  }
  
  
  static u8 * eap_ikev2_get_emsk(struct eap_sm *sm, void *priv, size_t *len)
  {
  	struct eap_ikev2_data *data = priv;
  	u8 *key;
  
  	if (data->state != DONE || !data->keymat_ok)
  		return NULL;
  
  	key = os_malloc(EAP_EMSK_LEN);
  	if (key) {
  		os_memcpy(key, data->keymat + EAP_MSK_LEN, EAP_EMSK_LEN);
  		*len = EAP_EMSK_LEN;
  	}
  
  	return key;
  }
  
  
  int eap_server_ikev2_register(void)
  {
  	struct eap_method *eap;
  	int ret;
  
  	eap = eap_server_method_alloc(EAP_SERVER_METHOD_INTERFACE_VERSION,
  				      EAP_VENDOR_IETF, EAP_TYPE_IKEV2,
  				      "IKEV2");
  	if (eap == NULL)
  		return -1;
  
  	eap->init = eap_ikev2_init;
  	eap->reset = eap_ikev2_reset;
  	eap->buildReq = eap_ikev2_buildReq;
  	eap->check = eap_ikev2_check;
  	eap->process = eap_ikev2_process;
  	eap->isDone = eap_ikev2_isDone;
  	eap->getKey = eap_ikev2_getKey;
  	eap->isSuccess = eap_ikev2_isSuccess;
  	eap->get_emsk = eap_ikev2_get_emsk;
  
  	ret = eap_server_method_register(eap);
  	if (ret)
  		eap_server_method_free(eap);
  	return ret;
  }
  