freebsd-dev/contrib/wpa_supplicant/eap_psk.c
2005-06-05 20:52:14 +00:00

564 lines
15 KiB
C

/*
* WPA Supplicant / EAP-PSK (draft-bersani-eap-psk-05.txt)
* Copyright (c) 2004-2005, Jouni Malinen <jkmaline@cc.hut.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 <stdlib.h>
#include <stdio.h>
#include <string.h>
#include "common.h"
#include "eap_i.h"
#include "wpa_supplicant.h"
#include "config_ssid.h"
#include "md5.h"
#include "aes_wrap.h"
/* draft-bersani-eap-psk-03.txt mode. This is retained for interop testing and
* will be removed once an AS that supports draft5 becomes available. */
#define EAP_PSK_DRAFT3
#define EAP_PSK_RAND_LEN 16
#define EAP_PSK_MAC_LEN 16
#define EAP_PSK_TEK_LEN 16
#define EAP_PSK_MSK_LEN 64
#define EAP_PSK_R_FLAG_CONT 1
#define EAP_PSK_R_FLAG_DONE_SUCCESS 2
#define EAP_PSK_R_FLAG_DONE_FAILURE 3
/* EAP-PSK First Message (AS -> Supplicant) */
struct eap_psk_hdr_1 {
u8 code;
u8 identifier;
u16 length; /* including code, identifier, and length */
u8 type; /* EAP_TYPE_PSK */
#ifndef EAP_PSK_DRAFT3
u8 flags;
#endif /* EAP_PSK_DRAFT3 */
u8 rand_s[EAP_PSK_RAND_LEN];
#ifndef EAP_PSK_DRAFT3
/* Followed by variable length ID_S */
#endif /* EAP_PSK_DRAFT3 */
} __attribute__ ((packed));
/* EAP-PSK Second Message (Supplicant -> AS) */
struct eap_psk_hdr_2 {
u8 code;
u8 identifier;
u16 length; /* including code, identifier, and length */
u8 type; /* EAP_TYPE_PSK */
#ifndef EAP_PSK_DRAFT3
u8 flags;
u8 rand_s[EAP_PSK_RAND_LEN];
#endif /* EAP_PSK_DRAFT3 */
u8 rand_p[EAP_PSK_RAND_LEN];
u8 mac_p[EAP_PSK_MAC_LEN];
/* Followed by variable length ID_P */
} __attribute__ ((packed));
/* EAP-PSK Third Message (AS -> Supplicant) */
struct eap_psk_hdr_3 {
u8 code;
u8 identifier;
u16 length; /* including code, identifier, and length */
u8 type; /* EAP_TYPE_PSK */
#ifndef EAP_PSK_DRAFT3
u8 flags;
u8 rand_s[EAP_PSK_RAND_LEN];
#endif /* EAP_PSK_DRAFT3 */
u8 mac_s[EAP_PSK_MAC_LEN];
/* Followed by variable length PCHANNEL */
} __attribute__ ((packed));
/* EAP-PSK Fourth Message (Supplicant -> AS) */
struct eap_psk_hdr_4 {
u8 code;
u8 identifier;
u16 length; /* including code, identifier, and length */
u8 type; /* EAP_TYPE_PSK */
#ifndef EAP_PSK_DRAFT3
u8 flags;
u8 rand_s[EAP_PSK_RAND_LEN];
#endif /* EAP_PSK_DRAFT3 */
/* Followed by variable length PCHANNEL */
} __attribute__ ((packed));
struct eap_psk_data {
enum { PSK_INIT, PSK_MAC_SENT, PSK_DONE } state;
u8 rand_s[EAP_PSK_RAND_LEN];
u8 rand_p[EAP_PSK_RAND_LEN];
u8 ak[16], kdk[16], tek[EAP_PSK_TEK_LEN];
u8 *id_s, *id_p;
size_t id_s_len, id_p_len;
u8 key_data[EAP_PSK_MSK_LEN];
};
#define aes_block_size 16
static void eap_psk_key_setup(const u8 *psk, u8 *ak, u8 *kdk)
{
memset(ak, 0, aes_block_size);
aes_128_encrypt_block(psk, ak, ak);
memcpy(kdk, ak, aes_block_size);
ak[aes_block_size - 1] ^= 0x01;
kdk[aes_block_size - 1] ^= 0x02;
aes_128_encrypt_block(psk, ak, ak);
aes_128_encrypt_block(psk, kdk, kdk);
}
static void eap_psk_derive_keys(const u8 *kdk, const u8 *rb, u8 *tek, u8 *msk)
{
u8 hash[aes_block_size];
u8 counter = 1;
int i;
aes_128_encrypt_block(kdk, rb, hash);
hash[aes_block_size - 1] ^= counter;
aes_128_encrypt_block(kdk, hash, tek);
hash[aes_block_size - 1] ^= counter;
counter++;
for (i = 0; i < EAP_PSK_MSK_LEN / aes_block_size; i++) {
hash[aes_block_size - 1] ^= counter;
aes_128_encrypt_block(kdk, hash, &msk[i * aes_block_size]);
hash[aes_block_size - 1] ^= counter;
counter++;
}
}
static void * eap_psk_init(struct eap_sm *sm)
{
struct wpa_ssid *config = eap_get_config(sm);
struct eap_psk_data *data;
if (config == NULL || !config->eappsk) {
wpa_printf(MSG_INFO, "EAP-PSK: pre-shared key not configured");
return NULL;
}
data = malloc(sizeof(*data));
if (data == NULL)
return NULL;
memset(data, 0, sizeof(*data));
eap_psk_key_setup(config->eappsk, data->ak, data->kdk);
wpa_hexdump_key(MSG_DEBUG, "EAP-PSK: AK", data->ak, 16);
wpa_hexdump_key(MSG_DEBUG, "EAP-PSK: KDK", data->kdk, 16);
data->state = PSK_INIT;
if (config->nai) {
data->id_p = malloc(config->nai_len);
if (data->id_p)
memcpy(data->id_p, config->nai, config->nai_len);
data->id_p_len = config->nai_len;
}
if (data->id_p == NULL) {
wpa_printf(MSG_INFO, "EAP-PSK: could not get own identity");
free(data);
return NULL;
}
#ifdef EAP_PSK_DRAFT3
if (config->server_nai) {
data->id_s = malloc(config->server_nai_len);
if (data->id_s)
memcpy(data->id_s, config->server_nai,
config->server_nai_len);
data->id_s_len = config->server_nai_len;
}
if (data->id_s == NULL) {
wpa_printf(MSG_INFO, "EAP-PSK: could not get server identity");
free(data->id_p);
free(data);
return NULL;
}
#endif /* EAP_PSK_DRAFT3 */
return data;
}
static void eap_psk_deinit(struct eap_sm *sm, void *priv)
{
struct eap_psk_data *data = priv;
free(data->id_s);
free(data->id_p);
free(data);
}
static u8 * eap_psk_process_1(struct eap_sm *sm, struct eap_psk_data *data,
struct eap_method_ret *ret,
u8 *reqData, size_t reqDataLen,
size_t *respDataLen)
{
struct eap_psk_hdr_1 *hdr1;
struct eap_psk_hdr_2 *hdr2;
u8 *resp, *buf, *pos;
size_t buflen;
wpa_printf(MSG_DEBUG, "EAP-PSK: in INIT state");
hdr1 = (struct eap_psk_hdr_1 *) reqData;
if (reqDataLen < sizeof(*hdr1) ||
be_to_host16(hdr1->length) < sizeof(*hdr1) ||
be_to_host16(hdr1->length) > reqDataLen) {
wpa_printf(MSG_INFO, "EAP-PSK: Invalid first message "
"length (%lu %d; expected %lu or more)",
(unsigned long) reqDataLen,
be_to_host16(hdr1->length),
(unsigned long) sizeof(*hdr1));
ret->ignore = TRUE;
return NULL;
}
#ifndef EAP_PSK_DRAFT3
wpa_printf(MSG_DEBUG, "EAP-PSK: Flags=0x%x", hdr1->flags);
if ((hdr1->flags & 0x03) != 0) {
wpa_printf(MSG_INFO, "EAP-PSK: Unexpected T=%d (expected 0)",
hdr1->flags & 0x03);
ret->methodState = METHOD_DONE;
ret->decision = DECISION_FAIL;
return NULL;
}
#endif /* EAP_PSK_DRAFT3 */
wpa_hexdump(MSG_DEBUG, "EAP-PSK: RAND_S", hdr1->rand_s,
EAP_PSK_RAND_LEN);
memcpy(data->rand_s, hdr1->rand_s, EAP_PSK_RAND_LEN);
#ifndef EAP_PSK_DRAFT3
free(data->id_s);
data->id_s_len = be_to_host16(hdr1->length) - sizeof(*hdr1);
data->id_s = malloc(data->id_s_len);
if (data->id_s == NULL) {
wpa_printf(MSG_ERROR, "EAP-PSK: Failed to allocate memory for "
"ID_S (len=%d)", data->id_s_len);
ret->ignore = TRUE;
return NULL;
}
memcpy(data->id_s, (u8 *) (hdr1 + 1), data->id_s_len);
wpa_hexdump_ascii(MSG_DEBUG, "EAP-PSK: ID_S",
data->id_s, data->id_s_len);
#endif /* EAP_PSK_DRAFT3 */
if (hostapd_get_rand(data->rand_p, EAP_PSK_RAND_LEN)) {
wpa_printf(MSG_ERROR, "EAP-PSK: Failed to get random data");
ret->ignore = TRUE;
return NULL;
}
*respDataLen = sizeof(*hdr2) + data->id_p_len;
resp = malloc(*respDataLen);
if (resp == NULL)
return NULL;
hdr2 = (struct eap_psk_hdr_2 *) resp;
hdr2->code = EAP_CODE_RESPONSE;
hdr2->identifier = hdr1->identifier;
hdr2->length = host_to_be16(*respDataLen);
hdr2->type = EAP_TYPE_PSK;
#ifndef EAP_PSK_DRAFT3
hdr2->flags = 1; /* T=1 */
memcpy(hdr2->rand_s, hdr1->rand_s, EAP_PSK_RAND_LEN);
#endif /* EAP_PSK_DRAFT3 */
memcpy(hdr2->rand_p, data->rand_p, EAP_PSK_RAND_LEN);
memcpy((u8 *) (hdr2 + 1), data->id_p, data->id_p_len);
/* MAC_P = OMAC1-AES-128(AK, ID_P||ID_S||RAND_S||RAND_P) */
buflen = data->id_p_len + data->id_s_len + 2 * EAP_PSK_RAND_LEN;
buf = malloc(buflen);
if (buf == NULL) {
free(resp);
return NULL;
}
memcpy(buf, data->id_p, data->id_p_len);
pos = buf + data->id_p_len;
memcpy(pos, data->id_s, data->id_s_len);
pos += data->id_s_len;
memcpy(pos, data->rand_s, EAP_PSK_RAND_LEN);
pos += EAP_PSK_RAND_LEN;
memcpy(pos, data->rand_p, EAP_PSK_RAND_LEN);
omac1_aes_128(data->ak, buf, buflen, hdr2->mac_p);
free(buf);
wpa_hexdump(MSG_DEBUG, "EAP-PSK: RAND_P", hdr2->rand_p,
EAP_PSK_RAND_LEN);
wpa_hexdump(MSG_DEBUG, "EAP-PSK: MAC_P", hdr2->mac_p, EAP_PSK_MAC_LEN);
wpa_hexdump_ascii(MSG_DEBUG, "EAP-PSK: ID_P",
(u8 *) (hdr2 + 1), data->id_p_len);
data->state = PSK_MAC_SENT;
return resp;
}
static u8 * eap_psk_process_3(struct eap_sm *sm, struct eap_psk_data *data,
struct eap_method_ret *ret,
u8 *reqData, size_t reqDataLen,
size_t *respDataLen)
{
struct eap_psk_hdr_3 *hdr3;
struct eap_psk_hdr_4 *hdr4;
u8 *resp, *buf, *pchannel, *tag, *msg, nonce[16];
u8 mac[EAP_PSK_MAC_LEN];
size_t buflen, left;
int failed = 0;
wpa_printf(MSG_DEBUG, "EAP-PSK: in MAC_SENT state");
hdr3 = (struct eap_psk_hdr_3 *) reqData;
left = be_to_host16(hdr3->length);
if (left < sizeof(*hdr3) || reqDataLen < left) {
wpa_printf(MSG_INFO, "EAP-PSK: Invalid third message "
"length (%lu %d; expected %lu)",
(unsigned long) reqDataLen,
be_to_host16(hdr3->length),
(unsigned long) sizeof(*hdr3));
ret->ignore = TRUE;
return NULL;
}
left -= sizeof(*hdr3);
pchannel = (u8 *) (hdr3 + 1);
#ifndef EAP_PSK_DRAFT3
wpa_printf(MSG_DEBUG, "EAP-PSK: Flags=0x%x", hdr3->flags);
if ((hdr3->flags & 0x03) != 2) {
wpa_printf(MSG_INFO, "EAP-PSK: Unexpected T=%d (expected 2)",
hdr3->flags & 0x03);
ret->methodState = METHOD_DONE;
ret->decision = DECISION_FAIL;
return NULL;
}
wpa_hexdump(MSG_DEBUG, "EAP-PSK: RAND_S", hdr3->rand_s,
EAP_PSK_RAND_LEN);
/* TODO: would not need to store RAND_S since it is available in this
* message. For now, since we store this anyway, verify that it matches
* with whatever the server is sending. */
if (memcmp(hdr3->rand_s, data->rand_s, EAP_PSK_RAND_LEN) != 0) {
wpa_printf(MSG_ERROR, "EAP-PSK: RAND_S did not match");
ret->methodState = METHOD_DONE;
ret->decision = DECISION_FAIL;
return NULL;
}
#endif /* EAP_PSK_DRAFT3 */
wpa_hexdump(MSG_DEBUG, "EAP-PSK: MAC_S", hdr3->mac_s, EAP_PSK_MAC_LEN);
wpa_hexdump(MSG_DEBUG, "EAP-PSK: PCHANNEL", pchannel, left);
if (left < 4 + 16 + 1) {
wpa_printf(MSG_INFO, "EAP-PSK: Too short PCHANNEL data in "
"third message (len=%lu, expected 21)",
(unsigned long) left);
ret->ignore = TRUE;
return NULL;
}
/* MAC_S = OMAC1-AES-128(AK, ID_S||RAND_P) */
buflen = data->id_s_len + EAP_PSK_RAND_LEN;
buf = malloc(buflen);
if (buf == NULL)
return NULL;
memcpy(buf, data->id_s, data->id_s_len);
memcpy(buf + data->id_s_len, data->rand_p, EAP_PSK_RAND_LEN);
omac1_aes_128(data->ak, buf, buflen, mac);
free(buf);
if (memcmp(mac, hdr3->mac_s, EAP_PSK_MAC_LEN) != 0) {
wpa_printf(MSG_WARNING, "EAP-PSK: Invalid MAC_S in third "
"message");
ret->methodState = METHOD_DONE;
ret->decision = DECISION_FAIL;
return NULL;
}
wpa_printf(MSG_DEBUG, "EAP-PSK: MAC_S verified successfully");
eap_psk_derive_keys(data->kdk, data->rand_p, data->tek,
data->key_data);
wpa_hexdump_key(MSG_DEBUG, "EAP-PSK: TEK", data->tek, EAP_PSK_TEK_LEN);
wpa_hexdump_key(MSG_DEBUG, "EAP-PSK: MSK", data->key_data,
EAP_PSK_MSK_LEN);
memset(nonce, 0, 12);
memcpy(nonce + 12, pchannel, 4);
pchannel += 4;
left -= 4;
tag = pchannel;
pchannel += 16;
left -= 16;
msg = pchannel;
wpa_hexdump(MSG_MSGDUMP, "EAP-PSK: PCHANNEL - nonce",
nonce, sizeof(nonce));
wpa_hexdump(MSG_MSGDUMP, "EAP-PSK: PCHANNEL - hdr", reqData, 5);
wpa_hexdump(MSG_MSGDUMP, "EAP-PSK: PCHANNEL - cipher msg", msg, left);
#ifdef EAP_PSK_DRAFT3
if (aes_128_eax_decrypt(data->tek, nonce, sizeof(nonce),
reqData, 5, msg, left, tag))
#else /* EAP_PSK_DRAFT3 */
if (aes_128_eax_decrypt(data->tek, nonce, sizeof(nonce),
reqData, 22, msg, left, tag))
#endif /* EAP_PSK_DRAFT3 */
{
wpa_printf(MSG_WARNING, "EAP-PSK: PCHANNEL decryption failed");
return NULL;
}
wpa_hexdump(MSG_DEBUG, "EAP-PSK: Decrypted PCHANNEL message",
msg, left);
/* Verify R flag */
switch (msg[0] >> 6) {
case EAP_PSK_R_FLAG_CONT:
wpa_printf(MSG_DEBUG, "EAP-PSK: R flag - CONT - unsupported");
return NULL;
case EAP_PSK_R_FLAG_DONE_SUCCESS:
wpa_printf(MSG_DEBUG, "EAP-PSK: R flag - DONE_SUCCESS");
break;
case EAP_PSK_R_FLAG_DONE_FAILURE:
wpa_printf(MSG_DEBUG, "EAP-PSK: R flag - DONE_FAILURE");
wpa_printf(MSG_INFO, "EAP-PSK: Authentication server rejected "
"authentication");
failed = 1;
break;
}
*respDataLen = sizeof(*hdr4) + 4 + 16 + 1;
resp = malloc(*respDataLen);
if (resp == NULL)
return NULL;
hdr4 = (struct eap_psk_hdr_4 *) resp;
hdr4->code = EAP_CODE_RESPONSE;
hdr4->identifier = hdr3->identifier;
hdr4->length = host_to_be16(*respDataLen);
hdr4->type = EAP_TYPE_PSK;
#ifndef EAP_PSK_DRAFT3
hdr4->flags = 3; /* T=3 */
memcpy(hdr4->rand_s, hdr3->rand_s, EAP_PSK_RAND_LEN);
#endif /* EAP_PSK_DRAFT3 */
pchannel = (u8 *) (hdr4 + 1);
/* nonce++ */
inc_byte_array(nonce, sizeof(nonce));
memcpy(pchannel, nonce + 12, 4);
pchannel[4 + 16] = EAP_PSK_R_FLAG_DONE_SUCCESS << 6;
wpa_hexdump(MSG_DEBUG, "EAP-PSK: reply message (plaintext)",
pchannel + 4 + 16, 1);
#ifdef EAP_PSK_DRAFT3
aes_128_eax_encrypt(data->tek, nonce, sizeof(nonce), resp, 5,
pchannel + 4 + 16, 1, pchannel + 4);
#else /* EAP_PSK_DRAFT3 */
aes_128_eax_encrypt(data->tek, nonce, sizeof(nonce), resp, 22,
pchannel + 4 + 16, 1, pchannel + 4);
#endif /* EAP_PSK_DRAFT3 */
wpa_hexdump(MSG_DEBUG, "EAP-PSK: reply message (PCHANNEL)",
pchannel, 4 + 16 + 1);
wpa_printf(MSG_DEBUG, "EAP-PSK: Completed %ssuccessfully",
failed ? "un" : "");
data->state = PSK_DONE;
ret->methodState = METHOD_DONE;
ret->decision = failed ? DECISION_FAIL : DECISION_UNCOND_SUCC;
return resp;
}
static u8 * eap_psk_process(struct eap_sm *sm, void *priv,
struct eap_method_ret *ret,
u8 *reqData, size_t reqDataLen,
size_t *respDataLen)
{
struct eap_psk_data *data = priv;
struct eap_hdr *req;
u8 *pos, *resp = NULL;
size_t len;
req = (struct eap_hdr *) reqData;
pos = (u8 *) (req + 1);
if (reqDataLen < sizeof(*req) + 1 || *pos != EAP_TYPE_PSK ||
(len = be_to_host16(req->length)) > reqDataLen) {
wpa_printf(MSG_INFO, "EAP-PSK: Invalid frame");
ret->ignore = TRUE;
return NULL;
}
ret->ignore = FALSE;
ret->methodState = METHOD_CONT;
ret->decision = DECISION_FAIL;
ret->allowNotifications = TRUE;
switch (data->state) {
case PSK_INIT:
resp = eap_psk_process_1(sm, data, ret, reqData, len,
respDataLen);
break;
case PSK_MAC_SENT:
resp = eap_psk_process_3(sm, data, ret, reqData, len,
respDataLen);
break;
case PSK_DONE:
wpa_printf(MSG_DEBUG, "EAP-PSK: in DONE state - ignore "
"unexpected message");
ret->ignore = TRUE;
return NULL;
}
if (ret->methodState == METHOD_DONE) {
ret->allowNotifications = FALSE;
}
return resp;
}
static Boolean eap_psk_isKeyAvailable(struct eap_sm *sm, void *priv)
{
struct eap_psk_data *data = priv;
return data->state == PSK_DONE;
}
static u8 * eap_psk_getKey(struct eap_sm *sm, void *priv, size_t *len)
{
struct eap_psk_data *data = priv;
u8 *key;
if (data->state != PSK_DONE)
return NULL;
key = malloc(EAP_PSK_MSK_LEN);
if (key == NULL)
return NULL;
*len = EAP_PSK_MSK_LEN;
memcpy(key, data->key_data, EAP_PSK_MSK_LEN);
return key;
}
const struct eap_method eap_method_psk =
{
.method = EAP_TYPE_PSK,
.name = "PSK",
.init = eap_psk_init,
.deinit = eap_psk_deinit,
.process = eap_psk_process,
.isKeyAvailable = eap_psk_isKeyAvailable,
.getKey = eap_psk_getKey,
};