[PATCH v2 1/4] eapol: implement rekey support for authenticator

[James Prestwood <prestwoj@gmail.com>]

The only changes required was to set the secure bit for message 1,
reset the frame retry counter, and change the 2/4 verifier to use
the rekey flag rather than ptk_complete. This is because we must
set ptk_complete false in order to detect retransmissions of the
4/4 frame.

Initiating a rekey can now be done by simply calling eapol_start().
---
 src/eapol.c | 14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

diff --git a/src/eapol.c b/src/eapol.c
index 22b2d5d1..2048a87d 100644
--- a/src/eapol.c
+++ b/src/eapol.c
@@ -1086,8 +1086,6 @@ static void eapol_send_ptk_1_of_4(struct eapol_sm *sm)
 
 	handshake_state_new_anonce(sm->handshake);
 
-	sm->handshake->ptk_complete = false;
-
 	sm->replay_counter++;
 
 	memset(ek, 0, EAPOL_FRAME_LEN(sm->mic_len));
@@ -1111,6 +1109,12 @@ static void eapol_send_ptk_1_of_4(struct eapol_sm *sm)
 
 	eapol_key_data_append(ek, sm->mic_len, HANDSHAKE_KDE_PMKID, pmkid, 16);
 
+	if (sm->handshake->ptk_complete) {
+		ek->secure = true;
+		sm->rekey = true;
+		sm->handshake->ptk_complete = false;
+	}
+
 	ek->header.packet_len = L_CPU_TO_BE16(EAPOL_FRAME_LEN(sm->mic_len) +
 				EAPOL_KEY_DATA_LEN(ek, sm->mic_len) - 4);
 
@@ -1589,7 +1593,7 @@ static void eapol_handle_ptk_2_of_4(struct eapol_sm *sm,
 
 	l_debug("ifindex=%u", sm->handshake->ifindex);
 
-	if (!eapol_verify_ptk_2_of_4(ek, sm->handshake->ptk_complete))
+	if (!eapol_verify_ptk_2_of_4(ek, sm->rekey))
 		return;
 
 	if (L_BE64_TO_CPU(ek->key_replay_counter) != sm->replay_counter)
@@ -2482,6 +2486,8 @@ static void eapol_eap_complete_cb(enum eap_result result, void *user_data)
 
 		/* sm->mic_len will have been set in eapol_eap_results_cb */
 
+		sm->frame_retry = 0;
+
 		/* Kick off 4-Way Handshake */
 		eapol_ptk_1_of_4_retry(NULL, sm);
 	}
@@ -2873,6 +2879,8 @@ bool eapol_start(struct eapol_sm *sm)
 			if (L_WARN_ON(!sm->handshake->have_pmk))
 				return false;
 
+			sm->frame_retry = 0;
+
 			/* Kick off handshake */
 			eapol_ptk_1_of_4_retry(NULL, sm);
 		}
-- 
2.34.3