fragattacks/src/eap_peer/eap_tlv.c

/*
 * EAP peer method: EAP-TLV (draft-josefsson-pppext-eap-tls-eap-07.txt)
 * Copyright (c) 2004-2008, 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 "eap_i.h"
#include "eap_tlv.h"


/**
 * eap_tlv_build_nak - Build EAP-TLV NAK message
 * @id: EAP identifier for the header
 * @nak_type: TLV type (EAP_TLV_*)
 * Returns: Buffer to the allocated EAP-TLV NAK message or %NULL on failure
 *
 * This funtion builds an EAP-TLV NAK message. The caller is responsible for
 * freeing the returned buffer.
 */
struct wpabuf * eap_tlv_build_nak(int id, u16 nak_type)
{
	struct wpabuf *msg;

	msg = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_TLV, 10,
			    EAP_CODE_RESPONSE, id);
	if (msg == NULL)
		return NULL;

	wpabuf_put_u8(msg, 0x80); /* Mandatory */
	wpabuf_put_u8(msg, EAP_TLV_NAK_TLV);
	wpabuf_put_be16(msg, 6); /* Length */
	wpabuf_put_be32(msg, 0); /* Vendor-Id */
	wpabuf_put_be16(msg, nak_type); /* NAK-Type */

	return msg;
}


/**
 * eap_tlv_build_result - Build EAP-TLV Result message
 * @id: EAP identifier for the header
 * @status: Status (EAP_TLV_RESULT_SUCCESS or EAP_TLV_RESULT_FAILURE)
 * Returns: Buffer to the allocated EAP-TLV Result message or %NULL on failure
 *
 * This funtion builds an EAP-TLV Result message. The caller is responsible for
 * freeing the returned buffer.
 */
struct wpabuf * eap_tlv_build_result(int id, u16 status)
{
	struct wpabuf *msg;

	msg = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_TLV, 6,
			    EAP_CODE_RESPONSE, id);
	if (msg == NULL)
		return NULL;

	wpabuf_put_u8(msg, 0x80); /* Mandatory */
	wpabuf_put_u8(msg, EAP_TLV_RESULT_TLV);
	wpabuf_put_be16(msg, 2); /* Length */
	wpabuf_put_be16(msg, status); /* Status */

	return msg;
}


/**
 * eap_tlv_process - Process a received EAP-TLV message and generate a response
 * @sm: Pointer to EAP state machine allocated with eap_peer_sm_init()
 * @ret: Return values from EAP request validation and processing
 * @req: EAP-TLV request to be processed. The caller must have validated that
 * the buffer is large enough to contain full request (hdr->length bytes) and
 * that the EAP type is EAP_TYPE_TLV.
 * @resp: Buffer to return a pointer to the allocated response message. This
 * field should be initialized to %NULL before the call. The value will be
 * updated if a response message is generated. The caller is responsible for
 * freeing the allocated message.
 * @force_failure: Force negotiation to fail
 * Returns: 0 on success, -1 on failure
 */
int eap_tlv_process(struct eap_sm *sm, struct eap_method_ret *ret,
		    const struct wpabuf *req, struct wpabuf **resp,
		    int force_failure)
{
	size_t left, tlv_len;
	const u8 *pos;
	const u8 *result_tlv = NULL;
	size_t result_tlv_len = 0;
	int tlv_type, mandatory;

	/* Parse TLVs */
	pos = eap_hdr_validate(EAP_VENDOR_IETF, EAP_TYPE_TLV, req, &left);
	if (pos == NULL)
		return -1;
	wpa_hexdump(MSG_DEBUG, "EAP-TLV: Received TLVs", pos, left);
	while (left >= 4) {
		mandatory = !!(pos[0] & 0x80);
		tlv_type = WPA_GET_BE16(pos) & 0x3fff;
		pos += 2;
		tlv_len = WPA_GET_BE16(pos);
		pos += 2;
		left -= 4;
		if (tlv_len > left) {
			wpa_printf(MSG_DEBUG, "EAP-TLV: TLV underrun "
				   "(tlv_len=%lu left=%lu)",
				   (unsigned long) tlv_len,
				   (unsigned long) left);
			return -1;
		}
		switch (tlv_type) {
		case EAP_TLV_RESULT_TLV:
			result_tlv = pos;
			result_tlv_len = tlv_len;
			break;
		default:
			wpa_printf(MSG_DEBUG, "EAP-TLV: Unsupported TLV Type "
				   "%d%s", tlv_type,
				   mandatory ? " (mandatory)" : "");
			if (mandatory) {
				/* NAK TLV and ignore all TLVs in this packet.
				 */
				*resp = eap_tlv_build_nak(eap_get_id(req),
							  tlv_type);
				return *resp == NULL ? -1 : 0;
			}
			/* Ignore this TLV, but process other TLVs */
			break;
		}

		pos += tlv_len;
		left -= tlv_len;
	}
	if (left) {
		wpa_printf(MSG_DEBUG, "EAP-TLV: Last TLV too short in "
			   "Request (left=%lu)", (unsigned long) left);
		return -1;
	}

	/* Process supported TLVs */
	if (result_tlv) {
		int status, resp_status;
		wpa_hexdump(MSG_DEBUG, "EAP-TLV: Result TLV",
			    result_tlv, result_tlv_len);
		if (result_tlv_len < 2) {
			wpa_printf(MSG_INFO, "EAP-TLV: Too short Result TLV "
				   "(len=%lu)",
				   (unsigned long) result_tlv_len);
			return -1;
		}
		status = WPA_GET_BE16(result_tlv);
		if (status == EAP_TLV_RESULT_SUCCESS) {
			wpa_printf(MSG_INFO, "EAP-TLV: TLV Result - Success "
				   "- EAP-TLV/Phase2 Completed");
			if (force_failure) {
				wpa_printf(MSG_INFO, "EAP-TLV: Earlier failure"
					   " - force failed Phase 2");
				resp_status = EAP_TLV_RESULT_FAILURE;
				ret->decision = DECISION_FAIL;
			} else {
				resp_status = EAP_TLV_RESULT_SUCCESS;
				ret->decision = DECISION_UNCOND_SUCC;
			}
		} else if (status == EAP_TLV_RESULT_FAILURE) {
			wpa_printf(MSG_INFO, "EAP-TLV: TLV Result - Failure");
			resp_status = EAP_TLV_RESULT_FAILURE;
			ret->decision = DECISION_FAIL;
		} else {
			wpa_printf(MSG_INFO, "EAP-TLV: Unknown TLV Result "
				   "Status %d", status);
			resp_status = EAP_TLV_RESULT_FAILURE;
			ret->decision = DECISION_FAIL;
		}
		ret->methodState = METHOD_DONE;

		*resp = eap_tlv_build_result(eap_get_id(req), resp_status);
	}

	return 0;
}