/*
* 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 "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;
u32 token;
u16 group_num;
EAP_PWD_group *grp;
struct wpabuf *inbuf;
size_t in_frag_pos;
struct wpabuf *outbuf;
size_t out_frag_pos;
size_t mtu;
BIGNUM *k;
BIGNUM *private_value;
BIGNUM *peer_scalar;
BIGNUM *my_scalar;
EC_POINT *my_element;
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];
BN_CTX *bnctx;
};
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->bnctx = BN_CTX_new();
if (data->bnctx == NULL) {
wpa_printf(MSG_INFO, "EAP-PWD: bn context allocation fail");
bin_clear_free(data->password, data->password_len);
bin_clear_free(data->id_server, data->id_server_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;
BN_clear_free(data->private_value);
BN_clear_free(data->peer_scalar);
BN_clear_free(data->my_scalar);
BN_clear_free(data->k);
BN_CTX_free(data->bnctx);
EC_POINT_clear_free(data->my_element);
EC_POINT_clear_free(data->peer_element);
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);
if (data->grp) {
EC_GROUP_free(data->grp->group);
EC_POINT_clear_free(data->grp->pwe);
BN_clear_free(data->grp->order);
BN_clear_free(data->grp->prime);
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;
}
/* an lfsr is good enough to generate unpredictable tokens */
data->token = os_random();
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_hash ? EAP_PWD_PREP_MS :
EAP_PWD_PREP_NONE);
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)
{
BIGNUM *mask = NULL, *x = NULL, *y = NULL;
u8 *scalar = NULL, *element = NULL;
u16 offset;
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;
if (((data->private_value = BN_new()) == NULL) ||
((data->my_element = EC_POINT_new(data->grp->group)) == NULL) ||
((data->my_scalar = BN_new()) == NULL) ||
((mask = BN_new()) == NULL)) {
wpa_printf(MSG_INFO, "EAP-PWD (server): scalar allocation "
"fail");
goto fin;
}
if (BN_rand_range(data->private_value, data->grp->order) != 1 ||
BN_rand_range(mask, data->grp->order) != 1 ||
BN_add(data->my_scalar, data->private_value, mask) != 1 ||
BN_mod(data->my_scalar, data->my_scalar, data->grp->order,
data->bnctx) != 1) {
wpa_printf(MSG_INFO,
"EAP-pwd (server): unable to get randomness");
goto fin;
}
if (!EC_POINT_mul(data->grp->group, data->my_element, NULL,
data->grp->pwe, mask, data->bnctx)) {
wpa_printf(MSG_INFO, "EAP-PWD (server): element allocation "
"fail");
eap_pwd_state(data, FAILURE);
goto fin;
}
if (!EC_POINT_invert(data->grp->group, data->my_element, data->bnctx))
{
wpa_printf(MSG_INFO, "EAP-PWD (server): element inversion "
"fail");
goto fin;
}
BN_clear_free(mask);
if (((x = BN_new()) == NULL) ||
((y = BN_new()) == NULL)) {
wpa_printf(MSG_INFO, "EAP-PWD (server): point allocation "
"fail");
goto fin;
}
if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group,
data->my_element, x, y,
data->bnctx)) {
wpa_printf(MSG_INFO, "EAP-PWD (server): point assignment "
"fail");
goto fin;
}
if (((scalar = os_malloc(BN_num_bytes(data->grp->order))) == NULL) ||
((element = os_malloc(BN_num_bytes(data->grp->prime) * 2)) ==
NULL)) {
wpa_printf(MSG_INFO, "EAP-PWD (server): data allocation fail");
goto fin;
}
/*
* bignums occupy as little memory as possible so one that is
* sufficiently smaller than the prime or order might need pre-pending
* with zeros.
*/
os_memset(scalar, 0, BN_num_bytes(data->grp->order));
os_memset(element, 0, BN_num_bytes(data->grp->prime) * 2);
offset = BN_num_bytes(data->grp->order) -
BN_num_bytes(data->my_scalar);
BN_bn2bin(data->my_scalar, scalar + offset);
offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(x);
BN_bn2bin(x, element + offset);
offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(y);
BN_bn2bin(y, element + BN_num_bytes(data->grp->prime) + offset);
data->outbuf = wpabuf_alloc(2 * BN_num_bytes(data->grp->prime) +
BN_num_bytes(data->grp->order));
if (data->outbuf == NULL)
goto fin;
/* We send the element as (x,y) followed by the scalar */
wpabuf_put_data(data->outbuf, element,
2 * BN_num_bytes(data->grp->prime));
wpabuf_put_data(data->outbuf, scalar, BN_num_bytes(data->grp->order));
fin:
os_free(scalar);
os_free(element);
BN_clear_free(x);
BN_clear_free(y);
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)
{
BIGNUM *x = NULL, *y = NULL;
struct crypto_hash *hash;
u8 conf[SHA256_MAC_LEN], *cruft = NULL, *ptr;
u16 grp;
int offset;
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;
/* Each component of the cruft will be at most as big as the prime */
if (((cruft = os_malloc(BN_num_bytes(data->grp->prime))) == NULL) ||
((x = BN_new()) == NULL) || ((y = BN_new()) == NULL)) {
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
*/
os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(data->k);
BN_bn2bin(data->k, cruft + offset);
eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime));
/* server element: x, y */
if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group,
data->my_element, x, y,
data->bnctx)) {
wpa_printf(MSG_INFO, "EAP-PWD (server): confirm point "
"assignment fail");
goto fin;
}
os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(x);
BN_bn2bin(x, cruft + offset);
eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime));
os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(y);
BN_bn2bin(y, cruft + offset);
eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime));
/* server scalar */
os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
offset = BN_num_bytes(data->grp->order) -
BN_num_bytes(data->my_scalar);
BN_bn2bin(data->my_scalar, cruft + offset);
eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->order));
/* peer element: x, y */
if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group,
data->peer_element, x, y,
data->bnctx)) {
wpa_printf(MSG_INFO, "EAP-PWD (server): confirm point "
"assignment fail");
goto fin;
}
os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(x);
BN_bn2bin(x, cruft + offset);
eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime));
os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(y);
BN_bn2bin(y, cruft + offset);
eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime));
/* peer scalar */
os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
offset = BN_num_bytes(data->grp->order) -
BN_num_bytes(data->peer_scalar);
BN_bn2bin(data->peer_scalar, cruft + offset);
eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->order));
/* ciphersuite */
grp = htons(data->group_num);
os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
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);
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, BN_num_bytes(data->grp->prime));
BN_clear_free(x);
BN_clear_free(y);
if (data->outbuf == NULL)
eap_pwd_state(data, FAILURE);
}
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)) {
wpa_printf(MSG_INFO, "EAP-pwd: peer changed parameters");
eap_pwd_state(data, FAILURE);
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 = os_zalloc(sizeof(EAP_PWD_group));
if (data->grp == NULL) {
wpa_printf(MSG_INFO, "EAP-PWD: failed to allocate memory for "
"group");
return;
}
if (data->password_hash) {
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);
os_memset(pwhashhash, 0, 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...",
BN_num_bits(data->grp->prime));
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)
{
u8 *ptr;
BIGNUM *x = NULL, *y = NULL, *cofactor = NULL;
EC_POINT *K = NULL, *point = NULL;
int res = 0;
size_t prime_len, order_len;
wpa_printf(MSG_DEBUG, "EAP-pwd: Received commit response");
prime_len = BN_num_bytes(data->grp->prime);
order_len = BN_num_bytes(data->grp->order);
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;
}
if (((data->peer_scalar = BN_new()) == NULL) ||
((data->k = BN_new()) == NULL) ||
((cofactor = BN_new()) == NULL) ||
((x = BN_new()) == NULL) ||
((y = BN_new()) == NULL) ||
((point = EC_POINT_new(data->grp->group)) == NULL) ||
((K = EC_POINT_new(data->grp->group)) == NULL) ||
((data->peer_element = EC_POINT_new(data->grp->group)) == NULL)) {
wpa_printf(MSG_INFO, "EAP-PWD (server): peer data allocation "
"fail");
goto fin;
}
if (!EC_GROUP_get_cofactor(data->grp->group, cofactor, NULL)) {
wpa_printf(MSG_INFO, "EAP-PWD (server): unable to get "
"cofactor for curve");
goto fin;
}
/* element, x then y, followed by scalar */
ptr = (u8 *) payload;
BN_bin2bn(ptr, BN_num_bytes(data->grp->prime), x);
ptr += BN_num_bytes(data->grp->prime);
BN_bin2bn(ptr, BN_num_bytes(data->grp->prime), y);
ptr += BN_num_bytes(data->grp->prime);
BN_bin2bn(ptr, BN_num_bytes(data->grp->order), data->peer_scalar);
if (!EC_POINT_set_affine_coordinates_GFp(data->grp->group,
data->peer_element, x, y,
data->bnctx)) {
wpa_printf(MSG_INFO, "EAP-PWD (server): setting peer element "
"fail");
goto fin;
}
/* check to ensure peer's element is not in a small sub-group */
if (BN_cmp(cofactor, BN_value_one())) {
if (!EC_POINT_mul(data->grp->group, point, NULL,
data->peer_element, cofactor, NULL)) {
wpa_printf(MSG_INFO, "EAP-PWD (server): cannot "
"multiply peer element by order");
goto fin;
}
if (EC_POINT_is_at_infinity(data->grp->group, point)) {
wpa_printf(MSG_INFO, "EAP-PWD (server): peer element "
"is at infinity!\n");
goto fin;
}
}
/* compute the shared key, k */
if ((!EC_POINT_mul(data->grp->group, K, NULL, data->grp->pwe,
data->peer_scalar, data->bnctx)) ||
(!EC_POINT_add(data->grp->group, K, K, data->peer_element,
data->bnctx)) ||
(!EC_POINT_mul(data->grp->group, K, NULL, K, data->private_value,
data->bnctx))) {
wpa_printf(MSG_INFO, "EAP-PWD (server): computing shared key "
"fail");
goto fin;
}
/* ensure that the shared key isn't in a small sub-group */
if (BN_cmp(cofactor, BN_value_one())) {
if (!EC_POINT_mul(data->grp->group, K, NULL, K, cofactor,
NULL)) {
wpa_printf(MSG_INFO, "EAP-PWD (server): cannot "
"multiply shared key point by order!\n");
goto fin;
}
}
/*
* This check is strictly speaking just for the case above 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 (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 (!EC_POINT_get_affine_coordinates_GFp(data->grp->group, K, data->k,
NULL, data->bnctx)) {
wpa_printf(MSG_INFO, "EAP-PWD (server): unable to extract "
"shared secret from secret point");
goto fin;
}
res = 1;
fin:
EC_POINT_clear_free(K);
EC_POINT_clear_free(point);
BN_clear_free(cofactor);
BN_clear_free(x);
BN_clear_free(y);
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)
{
BIGNUM *x = NULL, *y = NULL;
struct crypto_hash *hash;
u32 cs;
u16 grp;
u8 conf[SHA256_MAC_LEN], *cruft = NULL, *ptr;
int offset;
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 */
if (((cruft = os_malloc(BN_num_bytes(data->grp->prime))) == NULL) ||
((x = BN_new()) == NULL) || ((y = BN_new()) == NULL)) {
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 */
os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(data->k);
BN_bn2bin(data->k, cruft + offset);
eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime));
/* peer element: x, y */
if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group,
data->peer_element, x, y,
data->bnctx)) {
wpa_printf(MSG_INFO, "EAP-PWD (server): confirm point "
"assignment fail");
goto fin;
}
os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(x);
BN_bn2bin(x, cruft + offset);
eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime));
os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(y);
BN_bn2bin(y, cruft + offset);
eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime));
/* peer scalar */
os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
offset = BN_num_bytes(data->grp->order) -
BN_num_bytes(data->peer_scalar);
BN_bn2bin(data->peer_scalar, cruft + offset);
eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->order));
/* server element: x, y */
if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group,
data->my_element, x, y,
data->bnctx)) {
wpa_printf(MSG_INFO, "EAP-PWD (server): confirm point "
"assignment fail");
goto fin;
}
os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(x);
BN_bn2bin(x, cruft + offset);
eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime));
os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(y);
BN_bn2bin(y, cruft + offset);
eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime));
/* server scalar */
os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
offset = BN_num_bytes(data->grp->order) -
BN_num_bytes(data->my_scalar);
BN_bn2bin(data->my_scalar, cruft + offset);
eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->order));
/* ciphersuite */
os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
eap_pwd_h_update(hash, (u8 *) &cs, sizeof(u32));
/* all done */
eap_pwd_h_final(hash, conf);
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->bnctx, 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, BN_num_bytes(data->grp->prime));
BN_clear_free(x);
BN_clear_free(y);
}
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)) {
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;
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) {
wpabuf_put_data(data->inbuf, pos, len);
data->in_frag_pos += len;
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_malloc(EAP_MSK_LEN);
if (key == NULL)
return NULL;
os_memcpy(key, data->msk, EAP_MSK_LEN);
*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_malloc(EAP_EMSK_LEN);
if (key == NULL)
return NULL;
os_memcpy(key, data->emsk, EAP_EMSK_LEN);
*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_malloc(1 + SHA256_MAC_LEN);
if (id == NULL)
return NULL;
os_memcpy(id, data->session_id, 1 + SHA256_MAC_LEN);
*len = 1 + SHA256_MAC_LEN;
return id;
}
int eap_server_pwd_register(void)
{
struct eap_method *eap;
int ret;
struct timeval tp;
struct timezone tz;
u32 sr;
sr = 0xdeaddada;
(void) gettimeofday(&tp, &tz);
sr ^= (tp.tv_sec ^ tp.tv_usec);
srandom(sr);
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;
ret = eap_server_method_register(eap);
if (ret)
eap_server_method_free(eap);
return ret;
}