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SAE: Add Rc variable and peer send-confirm validation 

This implements the behavior described in IEEE Std 802.11-2016,
12.4.8.6.6 (Protocol instance behavior - Accepted state) to silently
discard received Confirm message in the Accepted state if the new
message does not use an incremented send-confirm value or if the special
2^16-1 value is used. This avoids unnecessary processing of
retransmitted Confirm messages.

Signed-off-by: Jouni Malinen <j@w1.fi>
This commit is contained in:
Jouni Malinen 2017-12-27 12:14:41 +02:00
parent 9249afc8e1
commit abcbd0604c
2 changed files with 28 additions and 3 deletions
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30
src/ap/ieee802_11.c
View File

@ -963,12 +963,36 @@ static void handle_auth_sae(struct hostapd_data *hapd, struct sta_info *sta,
goto remove_sta;
if (sta->sae->state >= SAE_CONFIRMED ||
!(hapd->conf->mesh & MESH_ENABLED)) {
if (sae_check_confirm(sta->sae, mgmt->u.auth.variable,
((u8 *) mgmt) + len -
mgmt->u.auth.variable) < 0) {
const u8 *var;
size_t var_len;
u16 peer_send_confirm;
var = mgmt->u.auth.variable;
var_len = ((u8 *) mgmt) + len - mgmt->u.auth.variable;
if (var_len < 2) {
resp = WLAN_STATUS_UNSPECIFIED_FAILURE;
goto reply;
}
peer_send_confirm = WPA_GET_LE16(var);
if (sta->sae->state == SAE_ACCEPTED &&
(peer_send_confirm <= sta->sae->rc ||
peer_send_confirm == 0xffff)) {
wpa_printf(MSG_DEBUG,
"SAE: Silently ignore unexpected Confirm from peer "
MACSTR
" (peer-send-confirm=%u Rc=%u)",
MAC2STR(sta->addr),
peer_send_confirm, sta->sae->rc);
return;
}
if (sae_check_confirm(sta->sae, var, var_len) < 0) {
resp = WLAN_STATUS_UNSPECIFIED_FAILURE;
goto reply;
}
sta->sae->rc = peer_send_confirm;
}
resp = sae_sm_step(hapd, sta, mgmt->bssid, auth_transaction);
} else {

1
src/common/sae.h
View File

@ -53,6 +53,7 @@ struct sae_data {
struct crypto_bignum *peer_commit_scalar;
int group;
unsigned int sync; /* protocol instance variable: Sync */
u16 rc; /* protocol instance variable: Rc (received send-confirm) */
struct sae_temporary_data *tmp;
};