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EAP-pwd: Add support for fragmentation

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Signed-hostap: Dan Harkins <dharkins@lounge.org>
This commit is contained in:
Dan Harkins 2012-02-11 12:46:30 +02:00 • committed by Jouni Malinen
parent 27c9d333d4
commit 5ea93947ca
3 changed files with 484 additions and 141 deletions
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301
src/eap_peer/eap_pwd.c
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@ -32,6 +32,12 @@ struct eap_pwd_data {
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 *server_scalar;
@ -69,7 +75,7 @@ static const char * eap_pwd_state_txt(int state)
static void eap_pwd_state(struct eap_pwd_data *data, int state)
{
wpa_printf(MSG_INFO, "EAP-PWD: %s -> %s",
wpa_printf(MSG_DEBUG, "EAP-PWD: %s -> %s",
eap_pwd_state_txt(data->state), eap_pwd_state_txt(state));
data->state = state;
}
@ -124,6 +130,10 @@ static void * eap_pwd_init(struct eap_sm *sm)
os_memcpy(data->password, password, password_len);
data->password_len = password_len;
data->out_frag_pos = data->in_frag_pos = 0;
data->inbuf = data->outbuf = NULL;
data->mtu = 1020; /* default from RFC 5931, make it configurable! */
data->state = PWD_ID_Req;
return data;
@ -174,23 +184,24 @@ static u8 * eap_pwd_getkey(struct eap_sm *sm, void *priv, size_t *len)
}
static struct wpabuf *
static void
eap_pwd_perform_id_exchange(struct eap_sm *sm, struct eap_pwd_data *data,
struct eap_method_ret *ret,
const struct wpabuf *reqData,
const u8 *payload, size_t payload_len)
{
struct eap_pwd_id *id;
struct wpabuf *resp;
if (data->state != PWD_ID_Req) {
ret->ignore = TRUE;
return NULL;
eap_pwd_state(data, FAILURE);
return;
}
if (payload_len < sizeof(struct eap_pwd_id)) {
ret->ignore = TRUE;
return NULL;
eap_pwd_state(data, FAILURE);
return;
}
id = (struct eap_pwd_id *) payload;
@ -198,16 +209,18 @@ eap_pwd_perform_id_exchange(struct eap_sm *sm, struct eap_pwd_data *data,
if ((id->random_function != EAP_PWD_DEFAULT_RAND_FUNC) ||
(id->prf != EAP_PWD_DEFAULT_PRF)) {
ret->ignore = TRUE;
return NULL;
eap_pwd_state(data, FAILURE);
return;
}
wpa_printf(MSG_DEBUG, "EAP-PWD (peer): server said group %d",
wpa_printf(MSG_DEBUG, "EAP-PWD (peer): using group %d",
data->group_num);
data->id_server = os_malloc(payload_len - sizeof(struct eap_pwd_id));
if (data->id_server == NULL) {
wpa_printf(MSG_INFO, "EAP-PWD: memory allocation id fail");
return NULL;
eap_pwd_state(data, FAILURE);
return;
}
data->id_server_len = payload_len - sizeof(struct eap_pwd_id);
os_memcpy(data->id_server, id->identity, data->id_server_len);
@ -218,7 +231,8 @@ eap_pwd_perform_id_exchange(struct eap_sm *sm, struct eap_pwd_data *data,
NULL) {
wpa_printf(MSG_INFO, "EAP-PWD: failed to allocate memory for "
"group");
return NULL;
eap_pwd_state(data, FAILURE);
return;
}
/* compute PWE */
@ -228,39 +242,36 @@ eap_pwd_perform_id_exchange(struct eap_sm *sm, struct eap_pwd_data *data,
data->id_peer, data->id_peer_len,
id->token)) {
wpa_printf(MSG_INFO, "EAP-PWD (peer): unable to compute PWE");
return NULL;
eap_pwd_state(data, FAILURE);
return;
}
wpa_printf(MSG_INFO, "EAP-PWD (peer): computed %d bit PWE...",
wpa_printf(MSG_DEBUG, "EAP-PWD (peer): computed %d bit PWE...",
BN_num_bits(data->grp->prime));
resp = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_PWD,
1 + sizeof(struct eap_pwd_id) + data->id_peer_len,
EAP_CODE_RESPONSE, eap_get_id(reqData));
if (resp == NULL)
return NULL;
wpabuf_put_u8(resp, EAP_PWD_OPCODE_ID_EXCH);
wpabuf_put_be16(resp, data->group_num);
wpabuf_put_u8(resp, EAP_PWD_DEFAULT_RAND_FUNC);
wpabuf_put_u8(resp, EAP_PWD_DEFAULT_PRF);
wpabuf_put_data(resp, id->token, sizeof(id->token));
wpabuf_put_u8(resp, EAP_PWD_PREP_NONE);
wpabuf_put_data(resp, data->id_peer, data->id_peer_len);
data->outbuf = wpabuf_alloc(sizeof(struct eap_pwd_id) +
data->id_peer_len);
if (data->outbuf == NULL) {
eap_pwd_state(data, FAILURE);
return;
}
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, id->token, sizeof(id->token));
wpabuf_put_u8(data->outbuf, EAP_PWD_PREP_NONE);
wpabuf_put_data(data->outbuf, data->id_peer, data->id_peer_len);
eap_pwd_state(data, PWD_Commit_Req);
return resp;
}
static struct wpabuf *
static void
eap_pwd_perform_commit_exchange(struct eap_sm *sm, struct eap_pwd_data *data,
struct eap_method_ret *ret,
const struct wpabuf *reqData,
const u8 *payload, size_t payload_len)
{
struct wpabuf *resp = NULL;
EC_POINT *K = NULL, *point = NULL;
BIGNUM *mask = NULL, *x = NULL, *y = NULL, *cofactor = NULL;
u16 offset;
@ -422,18 +433,15 @@ eap_pwd_perform_commit_exchange(struct eap_sm *sm, struct eap_pwd_data *data,
offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(y);
BN_bn2bin(y, element + BN_num_bytes(data->grp->prime) + offset);
resp = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_PWD,
1 + BN_num_bytes(data->grp->order) +
(2 * BN_num_bytes(data->grp->prime)),
EAP_CODE_RESPONSE, eap_get_id(reqData));
if (resp == NULL)
data->outbuf = wpabuf_alloc(BN_num_bytes(data->grp->order) +
2 * BN_num_bytes(data->grp->prime));
if (data->outbuf == NULL)
goto fin;
wpabuf_put_u8(resp, EAP_PWD_OPCODE_COMMIT_EXCH);
/* we send the element as (x,y) follwed by the scalar */
wpabuf_put_data(resp, element, (2 * BN_num_bytes(data->grp->prime)));
wpabuf_put_data(resp, scalar, BN_num_bytes(data->grp->order));
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);
@ -443,22 +451,19 @@ fin:
BN_free(cofactor);
EC_POINT_free(K);
EC_POINT_free(point);
if (resp == NULL)
if (data->outbuf == NULL)
eap_pwd_state(data, FAILURE);
else
eap_pwd_state(data, PWD_Confirm_Req);
return resp;
}
static struct wpabuf *
static void
eap_pwd_perform_confirm_exchange(struct eap_sm *sm, struct eap_pwd_data *data,
struct eap_method_ret *ret,
const struct wpabuf *reqData,
const u8 *payload, size_t payload_len)
{
struct wpabuf *resp = NULL;
BIGNUM *x = NULL, *y = NULL;
HMAC_CTX ctx;
u32 cs;
@ -481,7 +486,7 @@ eap_pwd_perform_confirm_exchange(struct eap_sm *sm, struct eap_pwd_data *data,
/* 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 "
wpa_printf(MSG_INFO, "EAP-PWD (server): confirm allocation "
"fail");
goto fin;
}
@ -631,15 +636,6 @@ eap_pwd_perform_confirm_exchange(struct eap_sm *sm, struct eap_pwd_data *data,
/* all done */
H_Final(&ctx, conf);
resp = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_PWD,
1 + SHA256_DIGEST_LENGTH,
EAP_CODE_RESPONSE, eap_get_id(reqData));
if (resp == NULL)
goto fin;
wpabuf_put_u8(resp, EAP_PWD_OPCODE_CONFIRM_EXCH);
wpabuf_put_data(resp, conf, SHA256_DIGEST_LENGTH);
if (compute_keys(data->grp, data->bnctx, data->k,
data->my_scalar, data->server_scalar, conf, ptr,
&cs, data->msk, data->emsk) < 0) {
@ -648,20 +644,24 @@ eap_pwd_perform_confirm_exchange(struct eap_sm *sm, struct eap_pwd_data *data,
goto fin;
}
data->outbuf = wpabuf_alloc(SHA256_DIGEST_LENGTH);
if (data->outbuf == NULL)
goto fin;
wpabuf_put_data(data->outbuf, conf, SHA256_DIGEST_LENGTH);
fin:
os_free(cruft);
BN_free(x);
BN_free(y);
ret->methodState = METHOD_DONE;
if (resp == NULL) {
if (data->outbuf == NULL) {
ret->decision = DECISION_FAIL;
eap_pwd_state(data, FAILURE);
} else {
ret->decision = DECISION_UNCOND_SUCC;
eap_pwd_state(data, SUCCESS);
}
return resp;
}
@ -671,42 +671,199 @@ eap_pwd_process(struct eap_sm *sm, void *priv, struct eap_method_ret *ret,
{
struct eap_pwd_data *data = priv;
struct wpabuf *resp = NULL;
const u8 *pos;
const u8 *pos, *buf;
size_t len;
u8 exch;
u16 tot_len = 0;
u8 lm_exch;
pos = eap_hdr_validate(EAP_VENDOR_IETF, EAP_TYPE_PWD, reqData, &len);
if ((pos == NULL) || (len < 1)) {
wpa_printf(MSG_DEBUG, "EAP-pwd: Got a frame but pos is %s and "
"len is %d",
pos == NULL ? "NULL" : "not NULL", (int) len);
ret->ignore = TRUE;
return NULL;
}
wpa_printf(MSG_INFO, "EAP-pwd: Received frame: opcode %d", *pos);
ret->ignore = FALSE;
ret->methodState = METHOD_MAY_CONT;
ret->decision = DECISION_FAIL;
ret->allowNotifications = FALSE;
exch = *pos & 0x3f;
switch (exch) {
case EAP_PWD_OPCODE_ID_EXCH:
resp = eap_pwd_perform_id_exchange(sm, data, ret, reqData,
pos + 1, len - 1);
lm_exch = *pos;
pos++; /* skip over the bits and the exch */
len--;
/*
* we're fragmenting so send out the next fragment
*/
if (data->out_frag_pos) {
/*
* this should be an ACK
*/
if (len)
wpa_printf(MSG_INFO, "Bad Response! Fragmenting but "
"not an ACK");
wpa_printf(MSG_DEBUG, "EAP-pwd: Got an ACK for a fragment");
/*
* check if there are going to be more fragments
*/
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);
}
resp = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_PWD,
EAP_PWD_HDR_SIZE + len,
EAP_CODE_RESPONSE, eap_get_id(reqData));
if (resp == NULL) {
wpa_printf(MSG_INFO, "Unable to allocate memory for "
"next fragment!");
return NULL;
}
wpabuf_put_u8(resp, lm_exch);
buf = wpabuf_head_u8(data->outbuf);
wpabuf_put_data(resp, buf + data->out_frag_pos, len);
data->out_frag_pos += len;
/*
* this is the last fragment so get rid of the out buffer
*/
if (data->out_frag_pos >= wpabuf_len(data->outbuf)) {
wpabuf_free(data->outbuf);
data->out_frag_pos = 0;
}
wpa_printf(MSG_DEBUG, "EAP-pwd: Send %s fragment of %d bytes",
data->out_frag_pos == 0 ? "last" : "next",
(int) len);
return resp;
}
/*
* see if this is a fragment that needs buffering
*
* if it's the first fragment there'll be a length field
*/
if (EAP_PWD_GET_LENGTH_BIT(lm_exch)) {
tot_len = WPA_GET_BE16(pos);
wpa_printf(MSG_DEBUG, "EAP-pwd: Incoming fragments whose "
"total length = %d", tot_len);
data->inbuf = wpabuf_alloc(tot_len);
if (data->inbuf == NULL) {
wpa_printf(MSG_INFO, "Out of memory to buffer "
"fragments!");
return NULL;
}
pos += sizeof(u16);
len -= sizeof(u16);
}
/*
* buffer and ACK the fragment
*/
if (EAP_PWD_GET_MORE_BIT(lm_exch)) {
data->in_frag_pos += len;
if (data->in_frag_pos > wpabuf_size(data->inbuf)) {
wpa_printf(MSG_INFO, "EAP-pwd: Buffer overflow attack "
"detected (%d vs. %d)!",
(int) data->in_frag_pos,
(int) wpabuf_len(data->inbuf));
wpabuf_free(data->inbuf);
data->in_frag_pos = 0;
return NULL;
}
wpabuf_put_data(data->inbuf, pos, len);
resp = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_PWD,
EAP_PWD_HDR_SIZE,
EAP_CODE_RESPONSE, eap_get_id(reqData));
if (resp != NULL)
wpabuf_put_u8(resp, (EAP_PWD_GET_EXCHANGE(lm_exch)));
wpa_printf(MSG_DEBUG, "EAP-pwd: ACKing a %d byte fragment",
(int) len);
return resp;
}
/*
* we're buffering and this is the last fragment
*/
if (data->in_frag_pos) {
wpabuf_put_data(data->inbuf, pos, len);
wpa_printf(MSG_DEBUG, "EAP-pwd: Last fragment, %d bytes",
(int) len);
data->in_frag_pos += len;
pos = wpabuf_head_u8(data->inbuf);
len = data->in_frag_pos;
}
wpa_printf(MSG_DEBUG, "EAP-pwd: processing frame: exch %d, len %d",
EAP_PWD_GET_EXCHANGE(lm_exch), (int) len);
switch (EAP_PWD_GET_EXCHANGE(lm_exch)) {
case EAP_PWD_OPCODE_ID_EXCH:
eap_pwd_perform_id_exchange(sm, data, ret, reqData,
pos, len);
break;
case EAP_PWD_OPCODE_COMMIT_EXCH:
resp = eap_pwd_perform_commit_exchange(sm, data, ret, reqData,
pos + 1, len - 1);
case EAP_PWD_OPCODE_COMMIT_EXCH:
eap_pwd_perform_commit_exchange(sm, data, ret, reqData,
pos, len);
break;
case EAP_PWD_OPCODE_CONFIRM_EXCH:
resp = eap_pwd_perform_confirm_exchange(sm, data, ret, reqData,
pos + 1, len - 1);
case EAP_PWD_OPCODE_CONFIRM_EXCH:
eap_pwd_perform_confirm_exchange(sm, data, ret, reqData,
pos, len);
break;
default:
default:
wpa_printf(MSG_INFO, "EAP-pwd: Ignoring message with unknown "
"opcode %d", exch);
"opcode %d", lm_exch);
break;
}
/*
* if we buffered the just processed input now's the time to free it
*/
if (data->in_frag_pos) {
wpabuf_free(data->inbuf);
data->in_frag_pos = 0;
}
if (data->outbuf == NULL)
return NULL; /* generic failure */
/*
* we have output! Do we need to fragment it?
*/
len = wpabuf_len(data->outbuf);
if ((len + EAP_PWD_HDR_SIZE) > data->mtu) {
resp = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_PWD, data->mtu,
EAP_CODE_RESPONSE, eap_get_id(reqData));
/*
* if so it's the first so include a length field
*/
EAP_PWD_SET_LENGTH_BIT(lm_exch);
EAP_PWD_SET_MORE_BIT(lm_exch);
tot_len = len;
/*
* keep the packet at the MTU
*/
len = data->mtu - EAP_PWD_HDR_SIZE - sizeof(u16);
wpa_printf(MSG_DEBUG, "EAP-pwd: Fragmenting output, total "
"length = %d", tot_len);
} else {
resp = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_PWD,
EAP_PWD_HDR_SIZE + len,
EAP_CODE_RESPONSE, eap_get_id(reqData));
}
if (resp == NULL)
return NULL;
wpabuf_put_u8(resp, lm_exch);
if (EAP_PWD_GET_LENGTH_BIT(lm_exch)) {
wpabuf_put_be16(resp, tot_len);
data->out_frag_pos += len;
}
buf = wpabuf_head_u8(data->outbuf);
wpabuf_put_data(resp, buf, len);
/*
* if we're not fragmenting then there's no need to carry this around
*/
if (data->out_frag_pos == 0)
wpabuf_free(data->outbuf);
return resp;
}