[PATCH v2 18/18] ap: propogate IGTK and RSC to handshake

[John Brandt <brandtwjohn@gmail.com>]

When a client is connecting, remember whether it supports MFP, and if
so, propogate the IGTK to the handshake. Also get the current Receive
Sequence Counter (RSC) of the IGTK and propogate it to the handshake.
---
 src/ap.c | 61 +++++++++++++++++++++++++++++++++++++++++++++++---------
 1 file changed, 52 insertions(+), 9 deletions(-)

diff --git a/src/ap.c b/src/ap.c
index f598c173..c7ca49e8 100644
--- a/src/ap.c
+++ b/src/ap.c
@@ -144,6 +144,7 @@ struct sta_state {
 	struct eapol_sm *sm;
 	struct handshake_state *hs;
 	uint32_t gtk_query_cmd_id;
+	uint8_t prev_igtk_rsc[6];
 	struct l_idle *stop_handshake_work;
 	struct l_settings *wsc_settings;
 	uint8_t wsc_uuid_e[16];
@@ -154,6 +155,7 @@ struct sta_state {
 
 	bool ht_support : 1;
 	bool ht_greenfield : 1;
+	bool mfp : 1;
 };
 
 struct ap_wsc_pbc_probe_record {
@@ -1379,7 +1381,7 @@ static uint32_t ap_send_mgmt_frame(struct ap_state *ap,
 	}))
 
 static void ap_start_handshake(struct sta_state *sta, bool use_eapol_start,
-				const uint8_t *gtk_rsc)
+				const uint8_t *gtk_rsc, const uint8_t *igtk_rsc)
 {
 	struct ap_state *ap = sta->ap;
 	const uint8_t *own_addr = netdev_get_address(ap->netdev);
@@ -1401,6 +1403,9 @@ static void ap_start_handshake(struct sta_state *sta, bool use_eapol_start,
 	if (gtk_rsc)
 		handshake_state_set_gtk(sta->hs, sta->ap->gtk,
 					sta->ap->gtk_index, gtk_rsc);
+	if (sta->mfp && igtk_rsc)
+		handshake_state_set_igtk(sta->hs, sta->ap->igtk,
+					 sta->ap->igtk_index, igtk_rsc);
 
 	if (ap->netconfig_dhcp)
 		sta->hs->support_ip_allocation = true;
@@ -1506,7 +1511,8 @@ static void ap_handshake_event(struct handshake_state *hs,
 	va_end(args);
 }
 
-static void ap_start_rsna(struct sta_state *sta, const uint8_t *gtk_rsc)
+static void ap_start_rsna(struct sta_state *sta, const uint8_t *gtk_rsc,
+			  const uint8_t *igtk_rsc)
 {
 	/* this handshake setup assumes SAE or PSK network */
 	if (sta->hs && sta->akm_suite == IE_RSN_AKM_SUITE_SAE_SHA256) {
@@ -1521,7 +1527,7 @@ static void ap_start_rsna(struct sta_state *sta, const uint8_t *gtk_rsc)
 	handshake_state_set_event_func(sta->hs, ap_handshake_event, sta);
 	handshake_state_set_supplicant_ie(sta->hs, sta->assoc_rsne);
 
-	ap_start_handshake(sta, false, gtk_rsc);
+	ap_start_handshake(sta, false, gtk_rsc, igtk_rsc);
 }
 
 static void ap_gtk_query_cb(struct l_genl_msg *msg, void *user_data)
@@ -1546,13 +1552,48 @@ zero_rsc:
 		gtk_rsc = zero_gtk_rsc;
 	}
 
-	ap_start_rsna(sta, gtk_rsc);
+	ap_start_rsna(sta, gtk_rsc, sta->prev_igtk_rsc);
 	return;
 
 error:
 	ap_del_station(sta, MMPDU_REASON_CODE_UNSPECIFIED, true);
 }
 
+static void ap_igtk_query_cb(struct l_genl_msg *msg, void *user_data)
+{
+	struct sta_state *sta = user_data;
+	struct ap_state *ap = sta->ap;
+
+	const void *igtk_rsc;
+	uint8_t zero_igtk_rsc[6];
+	int err;
+
+	sta->gtk_query_cmd_id = 0;
+
+	err = l_genl_msg_get_error(msg);
+	if (err == -ENOTSUP)
+		goto zero_rsc;
+	else if (err < 0)
+		return;
+
+	igtk_rsc = nl80211_parse_get_key_seq(msg);
+	if (!igtk_rsc) {
+zero_rsc:
+		memset(zero_igtk_rsc, 0, 6);
+		igtk_rsc = zero_igtk_rsc;
+	}
+
+	memcpy(sta->prev_igtk_rsc, igtk_rsc, 6);
+
+	msg = nl80211_build_get_key(netdev_get_ifindex(ap->netdev),
+				    ap->gtk_index);
+	sta->gtk_query_cmd_id = l_genl_family_send(ap->nl80211, msg, ap_gtk_query_cb, sta, NULL);
+	if (!sta->gtk_query_cmd_id) {
+		l_genl_msg_unref(msg);
+		l_error("Issuing GET_KEY failed");
+	}
+}
+
 static void ap_stop_handshake_schedule(struct sta_state *sta)
 {
 	if (sta->stop_handshake_work)
@@ -1656,7 +1697,7 @@ static void ap_start_eap_wsc(struct sta_state *sta)
 	handshake_state_set_event_func(sta->hs, ap_wsc_handshake_event, sta);
 	handshake_state_set_8021x_config(sta->hs, sta->wsc_settings);
 
-	ap_start_handshake(sta, wait_for_eapol_start, NULL);
+	ap_start_handshake(sta, wait_for_eapol_start, NULL, NULL);
 }
 
 static struct l_genl_msg *ap_build_cmd_del_key(struct ap_state *ap, uint8_t index)
@@ -1834,13 +1875,13 @@ static void ap_associate_sta_cb(struct l_genl_msg *msg, void *user_data)
 	}
 
 	if (ap->group_cipher == IE_RSN_CIPHER_SUITE_NO_GROUP_TRAFFIC)
-		ap_start_rsna(sta, NULL);
+		ap_start_rsna(sta, NULL, NULL);
 	else {
 		msg = nl80211_build_get_key(netdev_get_ifindex(ap->netdev),
-					ap->gtk_index);
+					    sta->mfp ? ap->igtk_index : ap->gtk_index);
 		sta->gtk_query_cmd_id = l_genl_family_send(ap->nl80211, msg,
-								ap_gtk_query_cb,
-								sta, NULL);
+							   sta->mfp ? ap_igtk_query_cb : ap_gtk_query_cb,
+							   sta, NULL);
 		if (!sta->gtk_query_cmd_id) {
 			l_genl_msg_unref(msg);
 			l_error("Issuing GET_KEY failed");
@@ -2315,6 +2356,8 @@ static void ap_assoc_reassoc(struct sta_state *sta, bool reassoc,
 			err = MMPDU_REASON_CODE_INVALID_GROUP_CIPHER;
 			goto unsupported;
 		}
+
+		sta->mfp = rsn_info.mfpc && ap->mfpc;
 	}
 
 	/* 802.11-2016 11.3.5.3 j) */
-- 
2.45.0