[PATCH 02/14] AP: Support PASN with SAE key derivation

Signed-off-by: Ilan Peer <[email protected]>
---
 src/ap/ieee802_11.c | 284 ++++++++++++++++++++++++++++++++++++++++----
 src/ap/sta_info.c   |   3 +
 src/ap/sta_info.h   |   5 +
 3 files changed, 267 insertions(+), 25 deletions(-)

diff --git a/src/ap/ieee802_11.c b/src/ap/ieee802_11.c
index 7a16ec66b6..96972677fd 100644
--- a/src/ap/ieee802_11.c
+++ b/src/ap/ieee802_11.c
@@ -463,29 +463,16 @@ static void sae_set_state(struct sta_info *sta, enum sae_state state,
 }
 
 
-static struct wpabuf * auth_build_sae_commit(struct hostapd_data *hapd,
-					     struct sta_info *sta, int update,
-					     int status_code)
+static const char *sae_get_password(struct hostapd_data *hapd,
+				    struct sta_info *sta,
+				    const char *rx_id,
+				    struct sae_password_entry **pw_entry,
+				    struct sae_pt **s_pt)
 {
-	struct wpabuf *buf;
 	const char *password = NULL;
 	struct sae_password_entry *pw;
-	const char *rx_id = NULL;
-	int use_pt = 0;
 	struct sae_pt *pt = NULL;
 
-	if (sta->sae->tmp) {
-		rx_id = sta->sae->tmp->pw_id;
-		use_pt = sta->sae->tmp->h2e;
-	}
-
-	if (rx_id && hapd->conf->sae_pwe != 3)
-		use_pt = 1;
-	else if (status_code == WLAN_STATUS_SUCCESS)
-		use_pt = 0;
-	else if (status_code == WLAN_STATUS_SAE_HASH_TO_ELEMENT)
-		use_pt = 1;
-
 	for (pw = hapd->conf->sae_passwords; pw; pw = pw->next) {
 		if (!is_broadcast_ether_addr(pw->peer_addr) &&
 		    os_memcmp(pw->peer_addr, sta->addr, ETH_ALEN) != 0)
@@ -499,11 +486,44 @@ static struct wpabuf * auth_build_sae_commit(struct hostapd_data *hapd,
 		pt = pw->pt;
 		break;
 	}
+
 	if (!password) {
 		password = hapd->conf->ssid.wpa_passphrase;
 		pt = hapd->conf->ssid.pt;
 	}
-	if (!password || (use_pt && !pt)) {
+
+	if (pw_entry)
+		*pw_entry = pw;
+	if (s_pt)
+		*s_pt = pt;
+
+	return password;
+}
+
+
+static struct wpabuf *auth_build_sae_commit(struct hostapd_data *hapd,
+					    struct sta_info *sta, int update,
+					    int status_code)
+{
+	struct wpabuf *buf;
+	const char *password = NULL;
+	struct sae_password_entry *pw;
+	const char *rx_id = NULL;
+	int use_pt = 0;
+	struct sae_pt *pt = NULL;
+
+	if (sta->sae->tmp) {
+		rx_id = sta->sae->tmp->pw_id;
+		use_pt = sta->sae->tmp->h2e;
+	}
+
+	if (status_code == WLAN_STATUS_SUCCESS)
+		use_pt = 0;
+	else if (status_code == WLAN_STATUS_SAE_HASH_TO_ELEMENT)
+		use_pt = 1;
+
+	password = sae_get_password(hapd, sta, rx_id, &pw, &pt);
+	if (!password ||(use_pt && !pt)) {
 		wpa_printf(MSG_DEBUG, "SAE: No password available");
 		return NULL;
 	}
@@ -2225,6 +2245,181 @@ ieee802_11_set_radius_info(struct hostapd_data *hapd, struct sta_info *sta,
 
 
 #ifdef CONFIG_PASN
+#ifdef CONFIG_SAE
+
+static int pasn_wd_handle_sae_commit(struct hostapd_data *hapd,
+				     struct sta_info *sta,
+				     struct wpabuf *wd)
+{
+	struct pasn_data *pasn = sta->pasn;
+	const char *password = NULL;
+	const u8 *data;
+	size_t buf_len;
+	u16 res, alg, seq, status;
+	int groups[] = { pasn->group, 0 };
+	int ret;
+
+	if (!wd)
+		return -1;
+
+	data = wpabuf_head_u8(wd);
+	buf_len = wpabuf_len(wd);
+
+	if (buf_len < 6) {
+		wpa_printf(MSG_DEBUG, "PASN: SAE buffer too short. len=%lu",
+			   buf_len);
+		return -1;
+	}
+
+	alg = WPA_GET_LE16(data);
+	seq = WPA_GET_LE16(data + 2);
+	status = WPA_GET_LE16(data + 4);
+
+	wpa_printf(MSG_DEBUG, "PASN: SAE: commit: alg=%u, seq=%u, status=%u",
+		   alg, seq, status);
+
+	if (alg != WLAN_AUTH_SAE || seq != 1 || status != WLAN_STATUS_SUCCESS) {
+		wpa_printf(MSG_DEBUG, "PASN: SAE: dropping peer commit");
+		return -1;
+	}
+
+	sae_clear_data(&pasn->sae);
+	pasn->sae.state = SAE_NOTHING;
+
+	ret = sae_set_group(&pasn->sae, pasn->group);
+	if (ret) {
+		wpa_printf(MSG_DEBUG, "PASN: Failed to set SAE group");
+		return -1;
+	}
+
+	password = sae_get_password(hapd, sta, NULL, NULL, NULL);
+	if (!password) {
+		wpa_printf(MSG_DEBUG, "PASN: No SAE password found");
+		return -1;
+	}
+
+	ret = sae_prepare_commit(hapd->own_addr, sta->addr,
+				 (u8 *)password,
+				 os_strlen(password), 0,
+				 &pasn->sae);
+	if (ret) {
+		wpa_printf(MSG_DEBUG, "PASN: Failed to prepare SAE commit");
+		return -1;
+	}
+
+	res = sae_parse_commit(&pasn->sae, data + 6, buf_len - 6, NULL, 0,
+			       groups, 0);
+	if (res != WLAN_STATUS_SUCCESS) {
+		wpa_printf(MSG_DEBUG, "PASN: SAE failed parsing commit");
+		return -1;
+	}
+
+	/* process the commit message and derive the PMK */
+	ret = sae_process_commit(&pasn->sae);
+	if (ret) {
+		wpa_printf(MSG_DEBUG, "SAE: Failed to process peer commit");
+		return -1;
+	}
+
+	pasn->sae.state = SAE_COMMITTED;
+
+	return 0;
+}
+
+
+static int pasn_wd_handle_sae_confirm(struct hostapd_data *hapd,
+				      struct sta_info *sta,
+				      struct wpabuf *wd)
+{
+	struct pasn_data *pasn = sta->pasn;
+	const u8 *data;
+	size_t buf_len;
+	u16 res, alg, seq, status;
+
+	if (!wd)
+		return -1;
+
+	data = wpabuf_head_u8(wd);
+	buf_len = wpabuf_len(wd);
+
+	if (buf_len < 6) {
+		wpa_printf(MSG_DEBUG, "PASN: SAE buffer too short. len=%lu",
+			   buf_len);
+		return -1;
+	}
+
+	alg = WPA_GET_LE16(data);
+	seq = WPA_GET_LE16(data + 2);
+	status = WPA_GET_LE16(data + 4);
+
+	wpa_printf(MSG_DEBUG, "PASN: SAE: commit: alg=%u, seq=%u, status=%u",
+		   alg, seq, status);
+
+	if (alg != WLAN_AUTH_SAE || seq != 2 || status != WLAN_STATUS_SUCCESS) {
+		wpa_printf(MSG_DEBUG, "PASN: SAE: dropping peer commit");
+		return -1;
+	}
+
+	res = sae_check_confirm(&pasn->sae, data + 6, buf_len - 6);
+	if (res != WLAN_STATUS_SUCCESS) {
+		wpa_printf(MSG_DEBUG, "PASN: SAE failed checking confirm");
+		return -1;
+	}
+
+	pasn->sae.state = SAE_ACCEPTED;
+
+	/*
+	 * TODO: Based on on P802.11az_D2.0, the PMKSA derived with PASN/SAE
+	 * should only be allowed with future PASN only. For now do not restrict
+	 * this only for PASN.
+	 */
+	wpa_auth_pmksa_add_sae(hapd->wpa_auth, sta->addr,
+			       pasn->sae.pmk, pasn->sae.pmkid);
+	return 0;
+}
+
+
+static struct wpabuf *pasn_get_sae_wd(struct hostapd_data *hapd,
+				      struct sta_info *sta)
+{
+	struct pasn_data *pasn = sta->pasn;
+	struct wpabuf *buf = NULL;
+	u8 *len_ptr;
+	size_t len;
+
+	/* Need to add the entire authentication frame body */
+	buf = wpabuf_alloc(8 + SAE_COMMIT_MAX_LEN + 8 + SAE_CONFIRM_MAX_LEN);
+	if (!buf) {
+		wpa_printf(MSG_DEBUG, "PASN: Failed to allocate SAE buffer");
+		return NULL;
+	}
+
+	/* Need to add the entire authentication frame body for the commit */
+	len_ptr = wpabuf_put(buf, 2);
+	wpabuf_put_le16(buf, WLAN_AUTH_SAE);
+	wpabuf_put_le16(buf, 1);
+	wpabuf_put_le16(buf, WLAN_STATUS_SUCCESS);
+
+	/* write the actual commit and update the length accordingly */
+	sae_write_commit(&pasn->sae, buf, NULL, 0);
+	len = wpabuf_len(buf);
+	WPA_PUT_LE16(len_ptr, len - 2);
+
+	/* Need to add the entire authentication frame body for the confirm */
+	len_ptr = wpabuf_put(buf, 2);
+	wpabuf_put_le16(buf, WLAN_AUTH_SAE);
+	wpabuf_put_le16(buf, 2);
+	wpabuf_put_le16(buf, WLAN_STATUS_SUCCESS);
+
+	sae_write_confirm(&pasn->sae, buf);
+	WPA_PUT_LE16(len_ptr, wpabuf_len(buf) - len - 2);
+
+	pasn->sae.state = SAE_CONFIRMED;
+
+	return buf;
+}
+
+#endif /* CONFIG_SAE */
 
 static struct wpabuf *pasn_get_wrapped_data(struct hostapd_data *hapd,
 					    struct sta_info *sta)
@@ -2234,6 +2429,10 @@ static struct wpabuf *pasn_get_wrapped_data(struct hostapd_data *hapd,
 		/* no wrapped data */
 		return NULL;
 	case WPA_KEY_MGMT_SAE:
+#ifdef CONFIG_SAE
+		return pasn_get_sae_wd(hapd, sta);
+#endif /* CONFIG_SAE */
+		/* fall through */
 	case WPA_KEY_MGMT_FILS_SHA256:
 	case WPA_KEY_MGMT_FILS_SHA384:
 	case WPA_KEY_MGMT_FT_PSK:
@@ -2277,11 +2476,22 @@ pasn_derive_keys(struct hostapd_data *hapd, struct sta_info *sta,
 		pmk_len = pmksa->pmk_len;
 		os_memcpy(pmk, pmksa->pmk, pmksa->pmk_len);
 	} else {
-		/* TODO: derive PMK based on wrapped data */
-		wpa_printf(MSG_DEBUG,
-			   "PASN: missing implementation to derive PMK");
-
-		return -1;
+		switch (sta->pasn->akmp) {
+#ifdef CONFIG_SAE
+		case WPA_KEY_MGMT_SAE:
+			if (sta->pasn->sae.state == SAE_COMMITTED) {
+				pmk_len = PMK_LEN;
+				os_memcpy(pmk, sta->pasn->sae.pmk, PMK_LEN);
+				break;
+			}
+#endif /* CONFIG_SAE */
+			/* fall through */
+		default:
+			/* TODO: derive PMK based on wrapped data */
+			wpa_printf(MSG_DEBUG,
+				   "PASN: missing PMK derivation");
+			return -1;
+		}
 	}
 
 	ret = pasn_pmk_to_ptk(pmk, pmk_len,
@@ -2519,6 +2729,19 @@ static void handle_auth_pasn_1(struct hostapd_data *hapd, struct sta_info *sta,
 			status = WLAN_STATUS_UNSPECIFIED_FAILURE;
 			goto send_resp;
 		}
+
+#ifdef CONFIG_SAE
+		if (sta->pasn->akmp == WPA_KEY_MGMT_SAE) {
+			ret = pasn_wd_handle_sae_commit(hapd, sta,
+							wrapped_data);
+			if (ret) {
+				wpa_printf(MSG_DEBUG,
+					   "PASN: failed processing SAE commit");
+				status = WLAN_STATUS_UNSPECIFIED_FAILURE;
+				goto send_resp;
+			}
+		}
+#endif /* CONFIG_SAE */
 	}
 
 	sta->pasn->wrapped_data_format = pasn_params.wrapped_data_format;
@@ -2643,7 +2866,18 @@ static void handle_auth_pasn_3(struct hostapd_data *hapd, struct sta_info *sta,
 			goto fail;
 		}
 
-		/* TODO: handle wrapped data */
+#ifdef CONFIG_SAE
+		if (sta->pasn->akmp == WPA_KEY_MGMT_SAE) {
+			ret = pasn_wd_handle_sae_confirm(hapd, sta,
+							 wrapped_data);
+			if (ret) {
+				wpa_printf(MSG_DEBUG,
+					   "PASN: failed processing SAE confirm");
+				wpabuf_free(wrapped_data);
+				goto fail;
+			}
+		}
+#endif /* CONFIG_SAE */
 		wpabuf_free(wrapped_data);
 	}
 
diff --git a/src/ap/sta_info.c b/src/ap/sta_info.c
index bb2566d65b..44d6bbcd73 100644
--- a/src/ap/sta_info.c
+++ b/src/ap/sta_info.c
@@ -165,6 +165,9 @@ void ap_free_sta_pasn(struct hostapd_data *hapd, struct sta_info *sta)
 	if (sta->pasn) {
 		if (sta->pasn->ecdh)
 			crypto_ecdh_deinit(sta->pasn->ecdh);
+#ifdef CONFIG_SAE
+		sae_clear_data(&sta->pasn->sae);
+#endif /* CONFIG_SAE */
 		os_free(sta->pasn);
 		sta->pasn = NULL;
 	}
diff --git a/src/ap/sta_info.h b/src/ap/sta_info.h
index 1957d8ecd4..3da51a59a7 100644
--- a/src/ap/sta_info.h
+++ b/src/ap/sta_info.h
@@ -15,6 +15,7 @@
 #include "common/wpa_common.h"
 #include "common/ieee802_11_defs.h"
 #include "crypto/sha384.h"
+#include "common/sae.h"
 
 /* STA flags */
 #define WLAN_STA_AUTH BIT(0)
@@ -74,6 +75,10 @@ struct pasn_data {
 	u8 hash[SHA384_MAC_LEN];
 	struct wpa_ptk ptk;
 	struct crypto_ecdh *ecdh;
+
+#ifdef CONFIG_SAE
+	struct sae_data sae;
+#endif /* CONFIG_SAE */
 };
 
 struct sta_info {
-- 
2.17.1