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iwd/src/eapolutil.h
James Prestwood 374b367ba4 eapol: allow 16, 24 and 32 byte MIC lengths
The MIC length was hard coded to 16 bytes everywhere, and since several
AKMs require larger MIC's (24/32) this needed to change. The main issue
was that the MIC was hard coded to 16 bytes inside eapol_key. Instead
of doing this, the MIC, key_data_length, and key_data elements were all
bundled into key_data[0]. In order to retrieve the MIC, key_data_len,
or key_data several macros were introduced which account for the MIC
length provided.

A consequence of this is that all the verify functions inside eapol now
require the MIC length as a parameter because without it they cannot
determine the byte offset of key_data or key_data_length.

The MIC length for a given handshake is set inside the SM when starting
EAPoL. This length is determined by the AKM for the handshake.
2019-01-17 15:20:28 -06:00

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C

/*
*
* Wireless daemon for Linux
*
* Copyright (C) 2013-2014 Intel Corporation. All rights reserved.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*
*/
#include <stdint.h>
#include <stdbool.h>
#include <asm/byteorder.h>
#include <linux/types.h>
enum eapol_protocol_version {
EAPOL_PROTOCOL_VERSION_2001 = 1,
EAPOL_PROTOCOL_VERSION_2004 = 2,
};
/*
* 802.1X-2010: Table 11-5—Descriptor Type value assignments
* The WPA key type of 254 comes from somewhere else. Seems it is a legacy
* value that might still be used by older implementations
*/
enum eapol_descriptor_type {
EAPOL_DESCRIPTOR_TYPE_RC4 = 1,
EAPOL_DESCRIPTOR_TYPE_80211 = 2,
EAPOL_DESCRIPTOR_TYPE_WPA = 254,
};
enum eapol_key_descriptor_version {
EAPOL_KEY_DESCRIPTOR_VERSION_AKM_DEFINED = 0,
EAPOL_KEY_DESCRIPTOR_VERSION_HMAC_MD5_ARC4 = 1,
EAPOL_KEY_DESCRIPTOR_VERSION_HMAC_SHA1_AES = 2,
EAPOL_KEY_DESCRIPTOR_VERSION_AES_128_CMAC_AES = 3,
};
struct eapol_header {
uint8_t protocol_version;
uint8_t packet_type;
__be16 packet_len;
} __attribute__ ((packed));
struct eapol_frame {
struct eapol_header header;
uint8_t data[0];
} __attribute__ ((packed));
/* gets pointer to MIC */
#define EAPOL_KEY_MIC(ek) ((ek)->key_data)
/* get key data length */
#define EAPOL_KEY_DATA_LEN(ek, mic_len) l_get_be16((ek)->key_data + (mic_len))
/* gets pointer to key data */
#define EAPOL_KEY_DATA(ek, mic_len) ((ek)->key_data + (mic_len) + 2)
/* gets frame length (not including key data) */
#define EAPOL_FRAME_LEN(mic_len) sizeof(struct eapol_key) + (mic_len) + 2
struct eapol_key {
struct eapol_header header;
uint8_t descriptor_type;
#if defined(__LITTLE_ENDIAN_BITFIELD)
bool key_mic:1;
bool secure:1;
bool error:1;
bool request:1;
bool encrypted_key_data:1;
bool smk_message:1;
uint8_t reserved2:2;
uint8_t key_descriptor_version:3;
bool key_type:1;
uint8_t wpa_key_id:2; /* Bits 4-5 reserved in RSN, Key ID in WPA */
bool install:1;
bool key_ack:1;
#elif defined (__BIG_ENDIAN_BITFIELD)
uint8_t reserved2:2;
bool smk_message:1;
bool encrypted_key_data:1;
bool request:1;
bool error:1;
bool secure:1;
bool key_mic:1;
bool key_ack:1;
bool install:1;
uint8_t wpa_key_id:2; /* Bits 4-5 reserved in RSN, Key ID in WPA */
bool key_type:1;
uint8_t key_descriptor_version:3;
#else
#error "Please fix <asm/byteorder.h>"
#endif
__be16 key_length;
__be64 key_replay_counter;
uint8_t key_nonce[32];
uint8_t eapol_key_iv[16];
uint8_t key_rsc[8];
uint8_t reserved[8];
uint8_t key_data[0];
} __attribute__ ((packed));
const struct eapol_key *eapol_key_validate(const uint8_t *frame, size_t len,
size_t mic_len);