Clear WPA group keys from memory before initiating a key exchange

with an access point. Prevents false positive 'reused group key'
warnings in dmesg when re-associating to the same access point.
Problem reported by tb@
ok tb@

3 files changed, 21 insertions, 11 deletions

diff --git a/sys/net80211/ieee80211_crypto.c b/sys/net80211/ieee80211_crypto.c
index c534bf6dc29..db68889c548 100644
--- a/sys/net80211/ieee80211_crypto.c
+++ b/sys/net80211/ieee80211_crypto.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: ieee80211_crypto.c,v 1.70 2017/05/02 17:07:06 mikeb Exp $	*/
+/*	$OpenBSD: ieee80211_crypto.c,v 1.71 2017/08/18 17:30:12 stsp Exp $	*/
 
 /*-
  * Copyright (c) 2008 Damien Bergamini <damien.bergamini@free.fr>
@@ -74,13 +74,11 @@ ieee80211_crypto_attach(struct ifnet *ifp)
 #endif
 }
 
-
 void
 ieee80211_crypto_detach(struct ifnet *ifp)
 {
 	struct ieee80211com *ic = (void *)ifp;
 	struct ieee80211_pmk *pmk;
-	int i;
 
 	/* purge the PMKSA cache */
 	while ((pmk = TAILQ_FIRST(&ic->ic_pmksa)) != NULL) {
@@ -90,12 +88,7 @@ ieee80211_crypto_detach(struct ifnet *ifp)
 	}
 
 	/* clear all group keys from memory */
-	for (i = 0; i < IEEE80211_GROUP_NKID; i++) {
-		struct ieee80211_key *k = &ic->ic_nw_keys[i];
-		if (k->k_cipher != IEEE80211_CIPHER_NONE)
-			(*ic->ic_delete_key)(ic, NULL, k);
-		explicit_bzero(k, sizeof(*k));
-	}
+	ieee80211_crypto_clear_groupkeys(ic);
 
 	/* clear pre-shared key from memory */
 	explicit_bzero(ic->ic_psk, IEEE80211_PMK_LEN);
@@ -105,6 +98,19 @@ ieee80211_crypto_detach(struct ifnet *ifp)
 #endif
 }
 
+void
+ieee80211_crypto_clear_groupkeys(struct ieee80211com *ic)
+{
+	int i;
+
+	for (i = 0; i < IEEE80211_GROUP_NKID; i++) {
+		struct ieee80211_key *k = &ic->ic_nw_keys[i];
+		if (k->k_cipher != IEEE80211_CIPHER_NONE)
+			(*ic->ic_delete_key)(ic, NULL, k);
+		explicit_bzero(k, sizeof(*k));
+	}
+}
+
 /*
  * Return the length in bytes of a cipher suite key (see Table 60).
  */
diff --git a/sys/net80211/ieee80211_crypto.h b/sys/net80211/ieee80211_crypto.h
index 8881b3896e7..348d035c283 100644
--- a/sys/net80211/ieee80211_crypto.h
+++ b/sys/net80211/ieee80211_crypto.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: ieee80211_crypto.h,v 1.24 2016/12/17 18:35:54 stsp Exp $	*/
+/*	$OpenBSD: ieee80211_crypto.h,v 1.25 2017/08/18 17:30:12 stsp Exp $	*/
 
 /*-
  * Copyright (c) 2007,2008 Damien Bergamini <damien.bergamini@free.fr>
@@ -111,6 +111,7 @@ struct	ieee80211_node;
 void	ieee80211_crypto_attach(struct ifnet *);
 void	ieee80211_crypto_detach(struct ifnet *);
 
+void	ieee80211_crypto_clear_groupkeys(struct ieee80211com *);
 struct	ieee80211_key *ieee80211_get_txkey(struct ieee80211com *,
 	    const struct ieee80211_frame *, struct ieee80211_node *);
 struct	ieee80211_key *ieee80211_get_rxkey(struct ieee80211com *,
diff --git a/sys/net80211/ieee80211_proto.c b/sys/net80211/ieee80211_proto.c
index 9eab14598b9..c0978acfc31 100644
--- a/sys/net80211/ieee80211_proto.c
+++ b/sys/net80211/ieee80211_proto.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: ieee80211_proto.c,v 1.79 2017/08/04 16:25:10 stsp Exp $	*/
+/*	$OpenBSD: ieee80211_proto.c,v 1.80 2017/08/18 17:30:12 stsp Exp $	*/
 /*	$NetBSD: ieee80211_proto.c,v 1.8 2004/04/30 23:58:20 dyoung Exp $	*/
 
 /*-
@@ -926,6 +926,7 @@ justcleanup:
 			break;
 		}
 		ni->ni_rsn_supp_state = RSNA_SUPP_INITIALIZE;
+		ieee80211_crypto_clear_groupkeys(ic);
 		break;
 	case IEEE80211_S_SCAN:
 		ic->ic_flags &= ~IEEE80211_F_SIBSS;
@@ -937,6 +938,7 @@ justcleanup:
 		ni->ni_associd = 0;
 		ni->ni_rstamp = 0;
 		ni->ni_rsn_supp_state = RSNA_SUPP_INITIALIZE;
+		ieee80211_crypto_clear_groupkeys(ic);
 		switch (ostate) {
 		case IEEE80211_S_INIT:
 #ifndef IEEE80211_STA_ONLY
@@ -980,6 +982,7 @@ justcleanup:
 		break;
 	case IEEE80211_S_AUTH:
 		ni->ni_rsn_supp_state = RSNA_SUPP_INITIALIZE;
+		ieee80211_crypto_clear_groupkeys(ic);
 		switch (ostate) {
 		case IEEE80211_S_INIT:
 			if (ifp->if_flags & IFF_DEBUG)