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OWE: Reuse own DH private key in AP if STA tries OWE association again

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This is a workaround for mac80211 behavior of retransmitting the
Association Request frames multiple times if the link layer retries
(i.e., seq# remains same) fail. The mac80211 initiated retransmission
will use a different seq# and as such, will go through duplicate
detection. If we were to change our DH key for that attempt, there would
be two different DH shared secrets and the STA would likely select the
wrong one.

Signed-off-by: Jouni Malinen <j@w1.fi>
This commit is contained in:
Jouni Malinen 2022-04-02 17:15:41 +03:00
parent 6ff8bda992
commit 65a3a273cd
1 changed files with 15 additions and 2 deletions
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17
src/ap/ieee802_11.c
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@ -4186,8 +4186,21 @@ static u16 owe_process_assoc_req(struct hostapd_data *hapd,
else
return WLAN_STATUS_FINITE_CYCLIC_GROUP_NOT_SUPPORTED;
crypto_ecdh_deinit(sta->owe_ecdh);
sta->owe_ecdh = crypto_ecdh_init(group);
if (sta->owe_group == group && sta->owe_ecdh) {
/* This is a workaround for mac80211 behavior of retransmitting
* the Association Request frames multiple times if the link
* layer retries (i.e., seq# remains same) fail. The mac80211
* initiated retransmission will use a different seq# and as
* such, will go through duplicate detection. If we were to
* change our DH key for that attempt, there would be two
* different DH shared secrets and the STA would likely select
* the wrong one. */
wpa_printf(MSG_DEBUG,
"OWE: Try to reuse own previous DH key since the STA tried to go through OWE association again");
} else {
crypto_ecdh_deinit(sta->owe_ecdh);
sta->owe_ecdh = crypto_ecdh_init(group);
}
if (!sta->owe_ecdh)
return WLAN_STATUS_FINITE_CYCLIC_GROUP_NOT_SUPPORTED;
sta->owe_group = group;