FILS: Add more complete support for FT-FILS use cases

This extends the original IEEE Std 802.11ai-2016 functionality with the
changes added in REVmd to describe how additional keys are derived to
protect the FT protocol using keys derived through FILS authentication.

This allows key_mgmt=FT-FILS-SHA256 to be used with FT protocol since
the FTE MIC can now be calculated following the changes in REVmd. The
FT-FILS-SHA384 case is still unsupported (it needs support for variable
length MIC field in FTE).

Signed-off-by: Jouni Malinen <jouni@codeaurora.org>

src/ap/wpa_auth_ft.c

@@ -1806,6 +1806,8 @@ u8 * wpa_sm_write_assoc_resp_ies(struct wpa_state_machine *sm, u8 *pos,
 	struct wpa_ft_ies parse;
 	u8 *ric_start;
 	u8 *anonce, *snonce;
+	const u8 *kck;
+	size_t kck_len;
 
 	if (sm == NULL)
 		return pos;
@@ -1898,9 +1900,15 @@ u8 * wpa_sm_write_assoc_resp_ies(struct wpa_state_machine *sm, u8 *pos,
 	if (ric_start == pos)
 		ric_start = NULL;
 
+	if (wpa_key_mgmt_fils(sm->wpa_key_mgmt)) {
+		kck = sm->PTK.kck2;
+		kck_len = sm->PTK.kck2_len;
+	} else {
+		kck = sm->PTK.kck;
+		kck_len = sm->PTK.kck_len;
+	}
 	if (auth_alg == WLAN_AUTH_FT &&
-	    wpa_ft_mic(sm->PTK.kck, sm->PTK.kck_len, sm->addr,
-		       sm->wpa_auth->addr, 6,
+	    wpa_ft_mic(kck, kck_len, sm->addr, sm->wpa_auth->addr, 6,
 		       mdie, mdie_len, ftie, ftie_len,
 		       rsnie, rsnie_len,
 		       ric_start, ric_start ? pos - ric_start : 0,
@@ -2310,6 +2318,8 @@ u16 wpa_ft_validate_reassoc(struct wpa_state_machine *sm, const u8 *ies,
 	u8 mic[WPA_EAPOL_KEY_MIC_MAX_LEN];
 	size_t mic_len = 16;
 	unsigned int count;
+	const u8 *kck;
+	size_t kck_len;
 
 	if (sm == NULL)
 		return WLAN_STATUS_UNSPECIFIED_FAILURE;
@@ -2423,8 +2433,14 @@ u16 wpa_ft_validate_reassoc(struct wpa_state_machine *sm, const u8 *ies,
 		return WLAN_STATUS_UNSPECIFIED_FAILURE;
 	}
 
-	if (wpa_ft_mic(sm->PTK.kck, sm->PTK.kck_len, sm->addr,
-		       sm->wpa_auth->addr, 5,
+	if (wpa_key_mgmt_fils(sm->wpa_key_mgmt)) {
+		kck = sm->PTK.kck2;
+		kck_len = sm->PTK.kck2_len;
+	} else {
+		kck = sm->PTK.kck;
+		kck_len = sm->PTK.kck_len;
+	}
+	if (wpa_ft_mic(kck, kck_len, sm->addr, sm->wpa_auth->addr, 5,
 		       parse.mdie - 2, parse.mdie_len + 2,
 		       parse.ftie - 2, parse.ftie_len + 2,
 		       parse.rsn - 2, parse.rsn_len + 2,

src/common/wpa_common.c

@@ -41,6 +41,21 @@ static unsigned int wpa_kck_len(int akmp, size_t pmk_len)
 }
 
 
+#ifdef CONFIG_IEEE80211R
+static unsigned int wpa_kck2_len(int akmp)
+{
+	switch (akmp) {
+	case WPA_KEY_MGMT_FT_FILS_SHA256:
+		return 16;
+	case WPA_KEY_MGMT_FT_FILS_SHA384:
+		return 24;
+	default:
+		return 0;
+	}
+}
+#endif /* CONFIG_IEEE80211R */
+
+
 static unsigned int wpa_kek_len(int akmp, size_t pmk_len)
 {
 	switch (akmp) {
@@ -61,6 +76,21 @@ static unsigned int wpa_kek_len(int akmp, size_t pmk_len)
 }
 
 
+#ifdef CONFIG_IEEE80211R
+static unsigned int wpa_kek2_len(int akmp)
+{
+	switch (akmp) {
+	case WPA_KEY_MGMT_FT_FILS_SHA256:
+		return 16;
+	case WPA_KEY_MGMT_FT_FILS_SHA384:
+		return 32;
+	default:
+		return 0;
+	}
+}
+#endif /* CONFIG_IEEE80211R */
+
+
 unsigned int wpa_mic_len(int akmp, size_t pmk_len)
 {
 	switch (akmp) {
@@ -404,6 +434,9 @@ int wpa_pmk_to_ptk(const u8 *pmk, size_t pmk_len, const char *label,
 	os_memcpy(ptk->tk, tmp + ptk->kck_len + ptk->kek_len, ptk->tk_len);
 	wpa_hexdump_key(MSG_DEBUG, "WPA: TK", ptk->tk, ptk->tk_len);
 
+	ptk->kek2_len = 0;
+	ptk->kck2_len = 0;
+
 	os_memset(tmp, 0, sizeof(tmp));
 	return 0;
 }
@@ -582,6 +615,9 @@ int fils_pmk_to_ptk(const u8 *pmk, size_t pmk_len, const u8 *spa, const u8 *aa,
 				fils_ft, *fils_ft_len);
 	}
 
+	ptk->kek2_len = 0;
+	ptk->kck2_len = 0;
+
 	os_memset(tmp, 0, sizeof(tmp));
 	ret = 0;
 err:
@@ -1470,8 +1506,8 @@ int wpa_pmk_r1_to_ptk(const u8 *pmk_r1, const u8 *snonce, const u8 *anonce,
 	u8 *pos, hash[32];
 	const u8 *addr[6];
 	size_t len[6];
-	u8 tmp[WPA_KCK_MAX_LEN + WPA_KEK_MAX_LEN + WPA_TK_MAX_LEN];
-	size_t ptk_len;
+	u8 tmp[2 * WPA_KCK_MAX_LEN + 2 * WPA_KEK_MAX_LEN + WPA_TK_MAX_LEN];
+	size_t ptk_len, offset;
 
 	/*
 	 * PTK = KDF-PTKLen(PMK-R1, "FT-PTK", SNonce || ANonce ||
@@ -1488,9 +1524,12 @@ int wpa_pmk_r1_to_ptk(const u8 *pmk_r1, const u8 *snonce, const u8 *anonce,
 	pos += ETH_ALEN;
 
 	ptk->kck_len = wpa_kck_len(akmp, PMK_LEN);
+	ptk->kck2_len = wpa_kck2_len(akmp);
 	ptk->kek_len = wpa_kek_len(akmp, PMK_LEN);
+	ptk->kek2_len = wpa_kek2_len(akmp);
 	ptk->tk_len = wpa_cipher_key_len(cipher);
-	ptk_len = ptk->kck_len + ptk->kek_len + ptk->tk_len;
+	ptk_len = ptk->kck_len + ptk->kek_len + ptk->tk_len +
+		ptk->kck2_len + ptk->kek2_len;
 
 	if (sha256_prf(pmk_r1, PMK_LEN, "FT-PTK", buf, pos - buf,
 		       tmp, ptk_len) < 0)
@@ -1518,11 +1557,23 @@ int wpa_pmk_r1_to_ptk(const u8 *pmk_r1, const u8 *snonce, const u8 *anonce,
 	os_memcpy(ptk_name, hash, WPA_PMK_NAME_LEN);
 
 	os_memcpy(ptk->kck, tmp, ptk->kck_len);
-	os_memcpy(ptk->kek, tmp + ptk->kck_len, ptk->kek_len);
-	os_memcpy(ptk->tk, tmp + ptk->kck_len + ptk->kek_len, ptk->tk_len);
+	offset = ptk->kck_len;
+	os_memcpy(ptk->kek, tmp + offset, ptk->kek_len);
+	offset += ptk->kek_len;
+	os_memcpy(ptk->tk, tmp + offset, ptk->tk_len);
+	offset += ptk->tk_len;
+	os_memcpy(ptk->kck2, tmp + offset, ptk->kck2_len);
+	offset = ptk->kck2_len;
+	os_memcpy(ptk->kek2, tmp + offset, ptk->kek2_len);
 
 	wpa_hexdump_key(MSG_DEBUG, "FT: KCK", ptk->kck, ptk->kck_len);
 	wpa_hexdump_key(MSG_DEBUG, "FT: KEK", ptk->kek, ptk->kek_len);
+	if (ptk->kck2_len)
+		wpa_hexdump_key(MSG_DEBUG, "FT: KCK2",
+				ptk->kck2, ptk->kck2_len);
+	if (ptk->kek2_len)
+		wpa_hexdump_key(MSG_DEBUG, "FT: KEK2",
+				ptk->kek2, ptk->kek2_len);
 	wpa_hexdump_key(MSG_DEBUG, "FT: TK", ptk->tk, ptk->tk_len);
 	wpa_hexdump(MSG_DEBUG, "FT: PTKName", ptk_name, WPA_PMK_NAME_LEN);
 

src/common/wpa_common.h

@@ -210,9 +210,13 @@ struct wpa_ptk {
 	u8 kck[WPA_KCK_MAX_LEN]; /* EAPOL-Key Key Confirmation Key (KCK) */
 	u8 kek[WPA_KEK_MAX_LEN]; /* EAPOL-Key Key Encryption Key (KEK) */
 	u8 tk[WPA_TK_MAX_LEN]; /* Temporal Key (TK) */
+	u8 kck2[WPA_KCK_MAX_LEN]; /* FT reasoc Key Confirmation Key (KCK2) */
+	u8 kek2[WPA_KEK_MAX_LEN]; /* FT reassoc Key Encryption Key (KEK2) */
 	size_t kck_len;
 	size_t kek_len;
 	size_t tk_len;
+	size_t kck2_len;
+	size_t kek2_len;
 	int installed; /* 1 if key has already been installed to driver */
 };
 

src/rsn_supp/wpa_ft.c

@@ -385,6 +385,8 @@ int wpa_ft_process_response(struct wpa_sm *sm, const u8 *ies, size_t ies_len,
 	u8 ptk_name[WPA_PMK_NAME_LEN];
 	int ret;
 	const u8 *bssid;
+	const u8 *kck;
+	size_t kck_len;
 
 	wpa_hexdump(MSG_DEBUG, "FT: Response IEs", ies, ies_len);
 	wpa_hexdump(MSG_DEBUG, "FT: RIC IEs", ric_ies, ric_ies_len);
@@ -485,9 +487,16 @@ int wpa_ft_process_response(struct wpa_sm *sm, const u8 *ies, size_t ies_len,
 			      ptk_name, sm->key_mgmt, sm->pairwise_cipher) < 0)
 		return -1;
 
+	if (wpa_key_mgmt_fils(sm->key_mgmt)) {
+		kck = sm->ptk.kck2;
+		kck_len = sm->ptk.kck2_len;
+	} else {
+		kck = sm->ptk.kck;
+		kck_len = sm->ptk.kck_len;
+	}
 	ft_ies = wpa_ft_gen_req_ies(sm, &ft_ies_len, ftie->anonce,
 				    sm->pmk_r1_name,
-				    sm->ptk.kck, sm->ptk.kck_len, bssid,
+				    kck, kck_len, bssid,
 				    ric_ies, ric_ies_len,
 				    parse.mdie ? parse.mdie - 2 : NULL);
 	if (ft_ies) {
@@ -679,6 +688,8 @@ int wpa_ft_validate_reassoc_resp(struct wpa_sm *sm, const u8 *ies,
 	struct rsn_ftie *ftie;
 	unsigned int count;
 	u8 mic[WPA_EAPOL_KEY_MIC_MAX_LEN];
+	const u8 *kck;
+	size_t kck_len;
 
 	wpa_hexdump(MSG_DEBUG, "FT: Response IEs", ies, ies_len);
 
@@ -776,7 +787,15 @@ int wpa_ft_validate_reassoc_resp(struct wpa_sm *sm, const u8 *ies,
 		return -1;
 	}
 
-	if (wpa_ft_mic(sm->ptk.kck, sm->ptk.kck_len, sm->own_addr, src_addr, 6,
+	if (wpa_key_mgmt_fils(sm->key_mgmt)) {
+		kck = sm->ptk.kck2;
+		kck_len = sm->ptk.kck2_len;
+	} else {
+		kck = sm->ptk.kck;
+		kck_len = sm->ptk.kck_len;
+	}
+
+	if (wpa_ft_mic(kck, kck_len, sm->own_addr, src_addr, 6,
 		       parse.mdie - 2, parse.mdie_len + 2,
 		       parse.ftie - 2, parse.ftie_len + 2,
 		       parse.rsn - 2, parse.rsn_len + 2,