jeltz/hostap
1
0
Fork 0
Code Issues Pull requests Projects Releases Wiki Activity

wpa_auth: Fix race in rejecting 4-way handshake for entropy

Browse source 
When there is not enough entropy and there are two station associating
at the same time, one of the stations will be rejected, but during
that rejection, the "reject_4way_hs_for_entropy" flag gets cleared. This
may allow the second station to avoid rejection and complete a 4-Way
Handshake with a GTK that will be cleared as soon as more entropy is
available and another station connects.

This reworks the logic to ban all 4-way handshakes until enough entropy
is available.

Signed-hostap: Nicolas Cavallari <cavallar@lri.fr>
This commit is contained in:
Nicolas Cavallari 2012-01-29 18:11:43 +02:00 committed by Jouni Malinen
parent 1193dc8fd7
commit 40d00d2bfe
1 changed files with 9 additions and 8 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

15
src/ap/wpa_auth.c
View file

@ -966,9 +966,7 @@ continue_processing:
wpa_printf(MSG_DEBUG, "WPA: Reject 4-way handshake to " wpa_printf(MSG_DEBUG, "WPA: Reject 4-way handshake to "
"collect more entropy for random number " "collect more entropy for random number "
"generation"); "generation");
sm->group->reject_4way_hs_for_entropy = FALSE;
random_mark_pool_ready(); random_mark_pool_ready();
sm->group->first_sta_seen = FALSE;
wpa_sta_disconnect(wpa_auth, sm->addr); wpa_sta_disconnect(wpa_auth, sm->addr);
return; return;
} }
@ -1614,9 +1612,11 @@ SM_STATE(WPA_PTK, AUTHENTICATION)
} }
static void wpa_group_first_station(struct wpa_authenticator *wpa_auth, static void wpa_group_ensure_init(struct wpa_authenticator *wpa_auth,
struct wpa_group *group) struct wpa_group *group)
{ {
if (group->first_sta_seen)
return;
/* /*
* System has run bit further than at the time hostapd was started * System has run bit further than at the time hostapd was started
* potentially very early during boot up. This provides better chances * potentially very early during boot up. This provides better chances
@ -1630,7 +1630,11 @@ static void wpa_group_first_station(struct wpa_authenticator *wpa_auth,
wpa_printf(MSG_INFO, "WPA: Not enough entropy in random pool " wpa_printf(MSG_INFO, "WPA: Not enough entropy in random pool "
"to proceed - reject first 4-way handshake"); "to proceed - reject first 4-way handshake");
group->reject_4way_hs_for_entropy = TRUE; group->reject_4way_hs_for_entropy = TRUE;
} else {
group->first_sta_seen = TRUE;
group->reject_4way_hs_for_entropy = FALSE;
} }
wpa_group_init_gmk_and_counter(wpa_auth, group); wpa_group_init_gmk_and_counter(wpa_auth, group);
wpa_gtk_update(wpa_auth, group); wpa_gtk_update(wpa_auth, group);
wpa_group_config_group_keys(wpa_auth, group); wpa_group_config_group_keys(wpa_auth, group);
@ -1641,10 +1645,7 @@ SM_STATE(WPA_PTK, AUTHENTICATION2)
{ {
SM_ENTRY_MA(WPA_PTK, AUTHENTICATION2, wpa_ptk); SM_ENTRY_MA(WPA_PTK, AUTHENTICATION2, wpa_ptk);
if (!sm->group->first_sta_seen) { wpa_group_ensure_init(sm->wpa_auth, sm->group);
wpa_group_first_station(sm->wpa_auth, sm->group);
sm->group->first_sta_seen = TRUE;
}
os_memcpy(sm->ANonce, sm->group->Counter, WPA_NONCE_LEN); os_memcpy(sm->ANonce, sm->group->Counter, WPA_NONCE_LEN);
wpa_hexdump(MSG_DEBUG, "WPA: Assign ANonce", sm->ANonce, wpa_hexdump(MSG_DEBUG, "WPA: Assign ANonce", sm->ANonce,