mesh: Add mesh robust security network

This implementation provides:

- Mesh SAE authentication mechanism
- Key management (set/get PSK)
- Cryptographic key establishment
- Enhanced protection mechanisms for robust management frames

Signed-off-by: Javier Lopez <jlopex@gmail.com>
Signed-off-by: Javier Cardona <javier@cozybit.com>
Signed-off-by: Jason Mobarak <x@jason.mobarak.name>
Signed-off-by: Thomas Pedersen <thomas@noack.us>

src/ap/sta_info.h

@@ -61,6 +61,11 @@ struct sta_info {
 	u16 my_lid;
 	u16 mpm_close_reason;
 	int mpm_retries;
+	u8 my_nonce[32];
+	u8 peer_nonce[32];
+	u8 aek[32];	/* SHA256 digest length */
+	u8 mtk[16];
+	u8 mgtk[16];
 #endif /* CONFIG_MESH */
 
 	unsigned int nonerp_set:1;

src/ap/wpa_auth.h

@@ -213,6 +213,9 @@ struct wpa_auth_callbacks {
 	int (*add_tspec)(void *ctx, const u8 *sta_addr, u8 *tspec_ie,
 			 size_t tspec_ielen);
 #endif /* CONFIG_IEEE80211R */
+#ifdef CONFIG_MESH
+	int (*start_ampe)(void *ctx, const u8 *sta_addr);
+#endif /* CONFIG_MESH */
 };
 
 struct wpa_authenticator * wpa_init(const u8 *addr,

wpa_supplicant/Android.mk

@@ -203,9 +203,16 @@ endif
 
 ifdef CONFIG_MESH
 NEED_80211_COMMON=y
+NEED_SHA256=y
+NEED_AES_SIV=y
+NEED_AES_OMAC1=y
+NEED_AES_CTR=y
+CONFIG_SAE=y
+CONFIG_AP=y
 L_CFLAGS += -DCONFIG_MESH
 OBJS += mesh.c
 OBJS += mesh_mpm.c
+OBJS += mesh_rsn.c
 endif
 
 ifdef CONFIG_SAE

wpa_supplicant/Makefile

@@ -206,9 +206,16 @@ endif
 
 ifdef CONFIG_MESH
 NEED_80211_COMMON=y
+NEED_SHA256=y
+NEED_AES_SIV=y
+NEED_AES_OMAC1=y
+NEED_AES_CTR=y
+CONFIG_SAE=y
+CONFIG_AP=y
 CFLAGS += -DCONFIG_MESH
 OBJS += mesh.o
 OBJS += mesh_mpm.o
+OBJS += mesh_rsn.o
 endif
 
 ifdef CONFIG_SAE

wpa_supplicant/mesh.c

@@ -22,6 +22,7 @@
 #include "driver_i.h"
 #include "notify.h"
 #include "mesh_mpm.h"
+#include "mesh_rsn.h"
 #include "mesh.h"
 
 
@@ -30,6 +31,8 @@ static void wpa_supplicant_mesh_deinit(struct wpa_supplicant *wpa_s)
 	wpa_supplicant_mesh_iface_deinit(wpa_s, wpa_s->ifmsh);
 	wpa_s->ifmsh = NULL;
 	wpa_s->current_ssid = NULL;
+	os_free(wpa_s->mesh_rsn);
+	wpa_s->mesh_rsn = NULL;
 	/* TODO: leave mesh (stop beacon). This will happen on link down
 	 * anyway, so it's not urgent */
 }
@@ -231,6 +234,10 @@ static int wpa_supplicant_mesh_init(struct wpa_supplicant *wpa_s,
 		len = os_strlen(ssid->passphrase);
 		bss->conf->ssid.wpa_passphrase =
 			dup_binstr(ssid->passphrase, len);
+
+		wpa_s->mesh_rsn = mesh_rsn_auth_init(wpa_s, mconf);
+		if (!wpa_s->mesh_rsn)
+			goto out_free;
 	}
 
 	return 0;

wpa_supplicant/mesh_mpm.c

@@ -17,6 +17,7 @@
 #include "wpa_supplicant_i.h"
 #include "driver_i.h"
 #include "mesh_mpm.h"
+#include "mesh_rsn.h"
 
 /* TODO make configurable */
 #define dot11MeshMaxRetries 10
@@ -212,7 +213,7 @@ static void mesh_mpm_send_plink_action(struct wpa_supplicant *wpa_s,
 	struct hostapd_data *bss = ifmsh->bss[0];
 	struct mesh_conf *conf = ifmsh->mconf;
 	u8 supp_rates[2 + 2 + 32];
-	u8 *pos;
+	u8 *pos, *cat;
 	u8 ie_len, add_plid = 0;
 	int ret;
 	int ampe = conf->security & MESH_CONF_SEC_AMPE;
@@ -234,6 +235,7 @@ static void mesh_mpm_send_plink_action(struct wpa_supplicant *wpa_s,
 	if (!buf)
 		return;
 
+	cat = wpabuf_mhead_u8(buf);
 	wpabuf_put_u8(buf, WLAN_ACTION_SELF_PROTECTED);
 	wpabuf_put_u8(buf, type);
 
@@ -303,9 +305,18 @@ static void mesh_mpm_send_plink_action(struct wpa_supplicant *wpa_s,
 		wpabuf_put_le16(buf, sta->peer_lid);
 	if (type == PLINK_CLOSE)
 		wpabuf_put_le16(buf, close_reason);
+	if (ampe)
+		mesh_rsn_get_pmkid(wpa_s->mesh_rsn, sta,
+				   wpabuf_put(buf, PMKID_LEN));
 
 	/* TODO HT IEs */
 
+	if (ampe && mesh_rsn_protect_frame(wpa_s->mesh_rsn, sta, cat, buf)) {
+		wpa_msg(wpa_s, MSG_INFO,
+			"Mesh MPM: failed to add AMPE and MIC IE");
+		goto fail;
+	}
+
 	ret = wpa_drv_send_action(wpa_s, wpa_s->assoc_freq, 0,
 				  sta->addr, wpa_s->own_addr, wpa_s->own_addr,
 				  wpabuf_head(buf), wpabuf_len(buf), 0);
@@ -313,6 +324,7 @@ static void mesh_mpm_send_plink_action(struct wpa_supplicant *wpa_s,
 		wpa_msg(wpa_s, MSG_INFO,
 			"Mesh MPM: failed to send peering frame");
 
+fail:
 	wpabuf_free(buf);
 }
 
@@ -462,6 +474,8 @@ void mesh_mpm_auth_peer(struct wpa_supplicant *wpa_s, const u8 *addr)
 	 * the AP code already sets this flag. */
 	sta->flags |= WLAN_STA_AUTH;
 
+	mesh_rsn_init_ampe_sta(wpa_s, sta);
+
 	os_memset(&params, 0, sizeof(params));
 	params.addr = sta->addr;
 	params.flags = WPA_STA_AUTHENTICATED | WPA_STA_AUTHORIZED;
@@ -539,7 +553,10 @@ void wpa_mesh_new_mesh_peer(struct wpa_supplicant *wpa_s, const u8 *addr,
 		return;
 	}
 
+	if (conf->security == MESH_CONF_SEC_NONE)
 		mesh_mpm_plink_open(wpa_s, sta, PLINK_OPEN_SENT);
+	else
+		mesh_rsn_auth_sae_sta(wpa_s, sta);
 }
 
 
@@ -559,10 +576,27 @@ static void mesh_mpm_plink_estab(struct wpa_supplicant *wpa_s,
 				 struct sta_info *sta)
 {
 	struct hostapd_data *hapd = wpa_s->ifmsh->bss[0];
+	struct mesh_conf *conf = wpa_s->ifmsh->mconf;
+	u8 seq[6] = {};
 
 	wpa_msg(wpa_s, MSG_INFO, "mesh plink with " MACSTR " established",
 		MAC2STR(sta->addr));
 
+	if (conf->security & MESH_CONF_SEC_AMPE) {
+		wpa_drv_set_key(wpa_s, WPA_ALG_CCMP, sta->addr, 0, 0,
+				seq, sizeof(seq), sta->mtk, sizeof(sta->mtk));
+		wpa_drv_set_key(wpa_s, WPA_ALG_CCMP, sta->addr, 1, 0,
+				seq, sizeof(seq),
+				sta->mgtk, sizeof(sta->mgtk));
+		wpa_drv_set_key(wpa_s, WPA_ALG_IGTK, sta->addr, 4, 0,
+				seq, sizeof(seq),
+				sta->mgtk, sizeof(sta->mgtk));
+
+		wpa_hexdump_key(MSG_DEBUG, "mtk:", sta->mtk, sizeof(sta->mtk));
+		wpa_hexdump_key(MSG_DEBUG, "mgtk:",
+				sta->mgtk, sizeof(sta->mgtk));
+	}
+
 	wpa_mesh_set_plink_state(wpa_s, sta, PLINK_ESTAB);
 	hapd->num_plinks++;
 
@@ -580,6 +614,7 @@ static void mesh_mpm_fsm(struct wpa_supplicant *wpa_s, struct sta_info *sta,
 			 enum plink_event event)
 {
 	struct hostapd_data *hapd = wpa_s->ifmsh->bss[0];
+	struct mesh_conf *conf = wpa_s->ifmsh->mconf;
 	u16 reason = 0;
 
 	wpa_msg(wpa_s, MSG_DEBUG, "MPM " MACSTR " state %s event %s",
@@ -652,6 +687,8 @@ static void mesh_mpm_fsm(struct wpa_supplicant *wpa_s, struct sta_info *sta,
 						   PLINK_CONFIRM, 0);
 			break;
 		case CNF_ACPT:
+			if (conf->security & MESH_CONF_SEC_AMPE)
+				mesh_rsn_derive_mtk(wpa_s, sta);
 			mesh_mpm_plink_estab(wpa_s, sta);
 			break;
 		default:
@@ -745,6 +782,7 @@ void mesh_mpm_action_rx(struct wpa_supplicant *wpa_s,
 {
 	u8 action_field;
 	struct hostapd_data *hapd = wpa_s->ifmsh->bss[0];
+	struct mesh_conf *mconf = wpa_s->ifmsh->mconf;
 	struct sta_info *sta;
 	u16 plid = 0, llid = 0;
 	enum plink_event event;
@@ -804,9 +842,21 @@ void mesh_mpm_action_rx(struct wpa_supplicant *wpa_s,
 	if (!sta)
 		return;
 
+#ifdef CONFIG_SAE
+	/* peer is in sae_accepted? */
+	if (sta->sae && sta->sae->state != SAE_ACCEPTED)
+		return;
+#endif /* CONFIG_SAE */
+
 	if (!sta->my_lid)
 		mesh_mpm_init_link(wpa_s, sta);
 
+	if (mconf->security & MESH_CONF_SEC_AMPE)
+		if (mesh_rsn_process_ampe(wpa_s, sta, &elems,
+					  &mgmt->u.action.category,
+					  ies, ie_len))
+			return;
+
 	if (sta->plink_state == PLINK_BLOCKED)
 		return;
 

wpa_supplicant/mesh_rsn.c

@@ -0,0 +1,573 @@
+/*
+ * WPA Supplicant - Mesh RSN routines
+ * Copyright (c) 2013-2014, cozybit, Inc.  All rights reserved.
+ *
+ * This software may be distributed under the terms of the BSD license.
+ * See README for more details.
+ */
+
+#include "utils/includes.h"
+
+#include "utils/common.h"
+#include "crypto/sha256.h"
+#include "crypto/random.h"
+#include "crypto/aes.h"
+#include "crypto/aes_siv.h"
+#include "rsn_supp/wpa.h"
+#include "ap/hostapd.h"
+#include "ap/wpa_auth.h"
+#include "ap/sta_info.h"
+#include "wpa_supplicant_i.h"
+#include "driver_i.h"
+#include "wpas_glue.h"
+#include "mesh_mpm.h"
+#include "mesh_rsn.h"
+
+
+static void auth_logger(void *ctx, const u8 *addr, logger_level level,
+			const char *txt)
+{
+	if (addr)
+		wpa_printf(MSG_DEBUG, "AUTH: " MACSTR " - %s",
+			   MAC2STR(addr), txt);
+	else
+		wpa_printf(MSG_DEBUG, "AUTH: %s", txt);
+}
+
+
+static const u8 *auth_get_psk(void *ctx, const u8 *addr,
+			      const u8 *p2p_dev_addr, const u8 *prev_psk)
+{
+	struct mesh_rsn *mesh_rsn = ctx;
+	struct hostapd_data *hapd = mesh_rsn->wpa_s->ifmsh->bss[0];
+	struct sta_info *sta = ap_get_sta(hapd, addr);
+
+	wpa_printf(MSG_DEBUG, "AUTH: %s (addr=" MACSTR " prev_psk=%p)",
+		   __func__, MAC2STR(addr), prev_psk);
+
+	if (sta && sta->auth_alg == WLAN_AUTH_SAE) {
+		if (!sta->sae || prev_psk)
+			return NULL;
+		return sta->sae->pmk;
+	}
+
+	return NULL;
+}
+
+
+static int auth_set_key(void *ctx, int vlan_id, enum wpa_alg alg,
+			const u8 *addr, int idx, u8 *key, size_t key_len)
+{
+	struct mesh_rsn *mesh_rsn = ctx;
+	u8 seq[6];
+
+	os_memset(seq, 0, sizeof(seq));
+
+	if (addr) {
+		wpa_printf(MSG_DEBUG, "AUTH: %s(alg=%d addr=" MACSTR
+			   " key_idx=%d)",
+			   __func__, alg, MAC2STR(addr), idx);
+	} else {
+		wpa_printf(MSG_DEBUG, "AUTH: %s(alg=%d key_idx=%d)",
+			   __func__, alg, idx);
+	}
+	wpa_hexdump_key(MSG_DEBUG, "AUTH: set_key - key", key, key_len);
+
+	return wpa_drv_set_key(mesh_rsn->wpa_s, alg, addr, idx,
+			       1, seq, 6, key, key_len);
+}
+
+
+static int auth_start_ampe(void *ctx, const u8 *addr)
+{
+	struct mesh_rsn *mesh_rsn = ctx;
+
+	if (mesh_rsn->wpa_s->current_ssid->mode != WPAS_MODE_MESH)
+		return -1;
+
+	mesh_mpm_auth_peer(mesh_rsn->wpa_s, addr);
+	return 0;
+}
+
+
+static int __mesh_rsn_auth_init(struct mesh_rsn *rsn, const u8 *addr)
+{
+	struct wpa_auth_config conf;
+	struct wpa_auth_callbacks cb;
+	u8 seq[6] = {};
+
+	wpa_printf(MSG_DEBUG, "AUTH: Initializing group state machine");
+
+	os_memset(&conf, 0, sizeof(conf));
+	conf.wpa = 2;
+	conf.wpa_key_mgmt = WPA_KEY_MGMT_SAE;
+	conf.wpa_pairwise = WPA_CIPHER_CCMP;
+	conf.rsn_pairwise = WPA_CIPHER_CCMP;
+	conf.wpa_group = WPA_CIPHER_CCMP;
+	conf.eapol_version = 0;
+	conf.wpa_group_rekey = -1;
+
+	os_memset(&cb, 0, sizeof(cb));
+	cb.ctx = rsn;
+	cb.logger = auth_logger;
+	cb.get_psk = auth_get_psk;
+	cb.set_key = auth_set_key;
+	cb.start_ampe = auth_start_ampe;
+
+	rsn->auth = wpa_init(addr, &conf, &cb);
+	if (rsn->auth == NULL) {
+		wpa_printf(MSG_DEBUG, "AUTH: wpa_init() failed");
+		return -1;
+	}
+
+	/* TODO: support rekeying */
+	if (random_get_bytes(rsn->mgtk, 16) < 0) {
+		wpa_deinit(rsn->auth);
+		return -1;
+	}
+
+	/* group mgmt */
+	wpa_drv_set_key(rsn->wpa_s, WPA_ALG_IGTK, NULL, 4, 1,
+			seq, sizeof(seq), rsn->mgtk, sizeof(rsn->mgtk));
+
+	/* group privacy / data frames */
+	wpa_drv_set_key(rsn->wpa_s, WPA_ALG_CCMP, NULL, 1, 1,
+			seq, sizeof(seq), rsn->mgtk, sizeof(rsn->mgtk));
+
+	return 0;
+}
+
+
+static void mesh_rsn_deinit(struct mesh_rsn *rsn)
+{
+	os_memset(rsn->mgtk, 0, sizeof(rsn->mgtk));
+	wpa_deinit(rsn->auth);
+}
+
+
+struct mesh_rsn *mesh_rsn_auth_init(struct wpa_supplicant *wpa_s,
+				    struct mesh_conf *conf)
+{
+	struct mesh_rsn *mesh_rsn;
+	struct hostapd_data *bss = wpa_s->ifmsh->bss[0];
+	const u8 *ie;
+	size_t ie_len;
+
+	mesh_rsn = os_zalloc(sizeof(*mesh_rsn));
+	if (mesh_rsn == NULL)
+		return NULL;
+	mesh_rsn->wpa_s = wpa_s;
+
+	if (__mesh_rsn_auth_init(mesh_rsn, wpa_s->own_addr) < 0) {
+		mesh_rsn_deinit(mesh_rsn);
+		return NULL;
+	}
+
+	bss->wpa_auth = mesh_rsn->auth;
+
+	ie = wpa_auth_get_wpa_ie(mesh_rsn->auth, &ie_len);
+	conf->ies = (u8 *) ie;
+	conf->ie_len = ie_len;
+
+	wpa_supplicant_rsn_supp_set_config(wpa_s, wpa_s->current_ssid);
+
+	return mesh_rsn;
+}
+
+
+static int index_within_array(const int *array, int idx)
+{
+	int i;
+
+	for (i = 0; i < idx; i++) {
+		if (array[i] == -1)
+			return 0;
+	}
+
+	return 1;
+}
+
+
+static int mesh_rsn_sae_group(struct wpa_supplicant *wpa_s,
+			      struct sae_data *sae)
+{
+	int *groups = wpa_s->ifmsh->bss[0]->conf->sae_groups;
+
+	/* Configuration may have changed, so validate current index */
+	if (!index_within_array(groups, wpa_s->mesh_rsn->sae_group_index))
+		return -1;
+
+	for (;;) {
+		int group = groups[wpa_s->mesh_rsn->sae_group_index];
+
+		if (group <= 0)
+			break;
+		if (sae_set_group(sae, group) == 0) {
+			wpa_dbg(wpa_s, MSG_DEBUG, "SME: Selected SAE group %d",
+				sae->group);
+			return 0;
+		}
+		wpa_s->mesh_rsn->sae_group_index++;
+	}
+
+	return -1;
+}
+
+
+struct wpabuf *
+mesh_rsn_build_sae_commit(struct wpa_supplicant *wpa_s,
+			  struct wpa_ssid *ssid, struct sta_info *sta)
+{
+	struct wpabuf *buf;
+	int len;
+
+	if (ssid->passphrase == NULL) {
+		wpa_msg(wpa_s, MSG_DEBUG, "SAE: No password available");
+		return NULL;
+	}
+
+	if (mesh_rsn_sae_group(wpa_s, sta->sae) < 0) {
+		wpa_msg(wpa_s, MSG_DEBUG, "SAE: Failed to select group");
+		return NULL;
+	}
+
+	if (sae_prepare_commit(wpa_s->own_addr, sta->addr,
+			       (u8 *) ssid->passphrase,
+			       os_strlen(ssid->passphrase), sta->sae) < 0) {
+		wpa_msg(wpa_s, MSG_DEBUG, "SAE: Could not pick PWE");
+		return NULL;
+	}
+
+	len = wpa_s->mesh_rsn->sae_token ?
+		wpabuf_len(wpa_s->mesh_rsn->sae_token) : 0;
+	buf = wpabuf_alloc(4 + SAE_COMMIT_MAX_LEN + len);
+	if (buf == NULL)
+		return NULL;
+
+	sae_write_commit(sta->sae, buf, wpa_s->mesh_rsn->sae_token);
+
+	return buf;
+}
+
+
+static void mesh_rsn_send_auth(struct wpa_supplicant *wpa_s,
+			       const u8 *dst, const u8 *src,
+			       u16 auth_transaction, u16 resp,
+			       struct wpabuf *data)
+{
+	struct ieee80211_mgmt *auth;
+	u8 *buf;
+	size_t len, ielen = 0;
+
+	if (data)
+		ielen = wpabuf_len(data);
+	len = IEEE80211_HDRLEN + sizeof(auth->u.auth) + ielen;
+	buf = os_zalloc(len);
+	if (buf == NULL)
+		return;
+
+	auth = (struct ieee80211_mgmt *) buf;
+	auth->frame_control = IEEE80211_FC(WLAN_FC_TYPE_MGMT,
+					   WLAN_FC_STYPE_AUTH);
+	os_memcpy(auth->da, dst, ETH_ALEN);
+	os_memcpy(auth->sa, src, ETH_ALEN);
+	os_memcpy(auth->bssid, src, ETH_ALEN);
+
+	auth->u.auth.auth_alg = host_to_le16(WLAN_AUTH_SAE);
+	auth->u.auth.auth_transaction = host_to_le16(auth_transaction);
+	auth->u.auth.status_code = host_to_le16(resp);
+
+	if (data)
+		os_memcpy(auth->u.auth.variable, wpabuf_head(data), ielen);
+
+	wpa_msg(wpa_s, MSG_DEBUG, "authentication frame: STA=" MACSTR
+		" auth_transaction=%d resp=%d (IE len=%lu)",
+		MAC2STR(dst), auth_transaction, resp, (unsigned long) ielen);
+	if (wpa_drv_send_mlme(wpa_s, buf, len, 0) < 0)
+		perror("send_auth_reply: send");
+
+	os_free(buf);
+}
+
+
+/* initiate new SAE authentication with sta */
+int mesh_rsn_auth_sae_sta(struct wpa_supplicant *wpa_s,
+			  struct sta_info *sta)
+{
+	struct wpa_ssid *ssid = wpa_s->current_ssid;
+	struct wpabuf *buf;
+
+	if (!sta->sae) {
+		sta->sae = os_zalloc(sizeof(*sta->sae));
+		if (sta->sae == NULL)
+			return -1;
+	}
+
+	buf = mesh_rsn_build_sae_commit(wpa_s, ssid, sta);
+	if (!buf)
+		return -1;
+
+	wpa_msg(wpa_s, MSG_DEBUG,
+		"AUTH: started authentication with SAE peer: " MACSTR,
+		MAC2STR(sta->addr));
+
+	sta->sae->state = SAE_COMMITTED;
+	wpa_supplicant_set_state(wpa_s, WPA_AUTHENTICATING);
+
+	mesh_rsn_send_auth(wpa_s, sta->addr, wpa_s->own_addr,
+			   1, WLAN_STATUS_SUCCESS, buf);
+
+	wpabuf_free(buf);
+
+	return 0;
+}
+
+
+void mesh_rsn_get_pmkid(struct mesh_rsn *rsn, struct sta_info *sta, u8 *pmkid)
+{
+	/* don't expect wpa auth to cache the pmkid for now */
+	rsn_pmkid(sta->sae->pmk, PMK_LEN, rsn->wpa_s->own_addr,
+		  sta->addr, pmkid,
+		  wpa_key_mgmt_sha256(wpa_auth_sta_key_mgmt(sta->wpa_sm)));
+}
+
+
+static void
+mesh_rsn_derive_aek(struct mesh_rsn *rsn, struct sta_info *sta)
+{
+	u8 *myaddr = rsn->wpa_s->own_addr;
+	u8 *peer = sta->addr;
+	u8 *addr1 = peer, *addr2 = myaddr;
+	u8 context[AES_BLOCK_SIZE];
+
+	/* SAE */
+	RSN_SELECTOR_PUT(context, wpa_cipher_to_suite(0, WPA_CIPHER_GCMP));
+
+	if (os_memcmp(myaddr, peer, ETH_ALEN) < 0) {
+		addr1 = myaddr;
+		addr2 = peer;
+	}
+	os_memcpy(context + 4, addr1, ETH_ALEN);
+	os_memcpy(context + 10, addr2, ETH_ALEN);
+
+	sha256_prf(sta->sae->pmk, sizeof(sta->sae->pmk), "AEK Derivation",
+		   context, sizeof(context), sta->aek, sizeof(sta->aek));
+}
+
+
+/* derive mesh temporal key from pmk */
+int mesh_rsn_derive_mtk(struct wpa_supplicant *wpa_s, struct sta_info *sta)
+{
+	u8 *ptr;
+	u8 *min, *max;
+	u16 min_lid, max_lid;
+	size_t nonce_len = sizeof(sta->my_nonce);
+	size_t lid_len = sizeof(sta->my_lid);
+	u8 *myaddr = wpa_s->own_addr;
+	u8 *peer = sta->addr;
+	/* 2 nonces, 2 linkids, akm suite, 2 mac addrs */
+	u8 context[64 + 4 + 4 + 12];
+
+	ptr = context;
+	if (os_memcmp(sta->my_nonce, sta->peer_nonce, nonce_len) < 0) {
+		min = sta->my_nonce;
+		max = sta->peer_nonce;
+	} else {
+		min = sta->peer_nonce;
+		max = sta->my_nonce;
+	}
+	os_memcpy(ptr, min, nonce_len);
+	os_memcpy(ptr + nonce_len, max, nonce_len);
+	ptr += 2 * nonce_len;
+
+	if (sta->my_lid < sta->peer_lid) {
+		min_lid = host_to_le16(sta->my_lid);
+		max_lid = host_to_le16(sta->peer_lid);
+	} else {
+		min_lid = host_to_le16(sta->peer_lid);
+		max_lid = host_to_le16(sta->my_lid);
+	}
+	os_memcpy(ptr, &min_lid, lid_len);
+	os_memcpy(ptr + lid_len, &max_lid, lid_len);
+	ptr += 2 * lid_len;
+
+	/* SAE */
+	RSN_SELECTOR_PUT(ptr, wpa_cipher_to_suite(0, WPA_CIPHER_GCMP));
+	ptr += 4;
+
+	if (os_memcmp(myaddr, peer, ETH_ALEN) < 0) {
+		min = myaddr;
+		max = peer;
+	} else {
+		min = peer;
+		max = myaddr;
+	}
+	os_memcpy(ptr, min, ETH_ALEN);
+	os_memcpy(ptr + ETH_ALEN, max, ETH_ALEN);
+
+	sha256_prf(sta->sae->pmk, sizeof(sta->sae->pmk),
+		   "Temporal Key Derivation", context, sizeof(context),
+		   sta->mtk, sizeof(sta->mtk));
+	return 0;
+}
+
+
+void mesh_rsn_init_ampe_sta(struct wpa_supplicant *wpa_s, struct sta_info *sta)
+{
+	if (random_get_bytes(sta->my_nonce, 32) < 0) {
+		wpa_printf(MSG_INFO, "mesh: Failed to derive random nonce");
+		/* TODO: How to handle this more cleanly? */
+	}
+	os_memset(sta->peer_nonce, 0, 32);
+	mesh_rsn_derive_aek(wpa_s->mesh_rsn, sta);
+}
+
+
+/* insert AMPE and encrypted MIC at @ie.
+ * @mesh_rsn: mesh RSN context
+ * @sta: STA we're sending to
+ * @cat: pointer to category code in frame header.
+ * @buf: wpabuf to add encrypted AMPE and MIC to.
+ * */
+int mesh_rsn_protect_frame(struct mesh_rsn *rsn, struct sta_info *sta,
+			   const u8 *cat, struct wpabuf *buf)
+{
+	struct ieee80211_ampe_ie *ampe;
+	u8 const *ie = wpabuf_head_u8(buf) + wpabuf_len(buf);
+	u8 *ampe_ie = NULL, *mic_ie = NULL, *mic_payload;
+	const u8 *aad[] = { rsn->wpa_s->own_addr, sta->addr, cat };
+	const size_t aad_len[] = { ETH_ALEN, ETH_ALEN, ie - cat };
+	int ret = 0;
+
+	if (AES_BLOCK_SIZE + 2 + sizeof(*ampe) + 2 > wpabuf_tailroom(buf)) {
+		wpa_printf(MSG_ERROR, "protect frame: buffer too small");
+		return -EINVAL;
+	}
+
+	ampe_ie = os_zalloc(2 + sizeof(*ampe));
+	if (!ampe_ie) {
+		wpa_printf(MSG_ERROR, "protect frame: out of memory");
+		return -ENOMEM;
+	}
+
+	mic_ie = os_zalloc(2 + AES_BLOCK_SIZE);
+	if (!mic_ie) {
+		wpa_printf(MSG_ERROR, "protect frame: out of memory");
+		ret = -ENOMEM;
+		goto free;
+	}
+
+	/*  IE: AMPE */
+	ampe_ie[0] = WLAN_EID_AMPE;
+	ampe_ie[1] = sizeof(*ampe);
+	ampe = (struct ieee80211_ampe_ie *) (ampe_ie + 2);
+
+	RSN_SELECTOR_PUT(ampe->selected_pairwise_suite,
+		     wpa_cipher_to_suite(WPA_PROTO_RSN, WPA_CIPHER_CCMP));
+	os_memcpy(ampe->local_nonce, sta->my_nonce, 32);
+	os_memcpy(ampe->peer_nonce, sta->peer_nonce, 32);
+	/* incomplete: see 13.5.4 */
+	/* TODO: static mgtk for now since we don't support rekeying! */
+	os_memcpy(ampe->mgtk, rsn->mgtk, 16);
+	/*  TODO: Populate Key RSC */
+	/*  expire in 13 decades or so */
+	os_memset(ampe->key_expiration, 0xff, 4);
+
+	/* IE: MIC */
+	mic_ie[0] = WLAN_EID_MIC;
+	mic_ie[1] = AES_BLOCK_SIZE;
+	wpabuf_put_data(buf, mic_ie, 2);
+	/* MIC field is output ciphertext */
+
+	/* encrypt after MIC */
+	mic_payload = (u8 *) wpabuf_put(buf, 2 + sizeof(*ampe) +
+					AES_BLOCK_SIZE);
+
+	if (aes_siv_encrypt(sta->aek, ampe_ie, 2 + sizeof(*ampe), 3,
+			    aad, aad_len, mic_payload)) {
+		wpa_printf(MSG_ERROR, "protect frame: failed to encrypt");
+		ret = -ENOMEM;
+		goto free;
+	}
+
+free:
+	os_free(ampe_ie);
+	os_free(mic_ie);
+
+	return ret;
+}
+
+
+int mesh_rsn_process_ampe(struct wpa_supplicant *wpa_s, struct sta_info *sta,
+			  struct ieee802_11_elems *elems, const u8 *cat,
+			  const u8 *start, size_t elems_len)
+{
+	int ret = 0;
+	struct ieee80211_ampe_ie *ampe;
+	u8 null_nonce[32] = {};
+	u8 ampe_eid;
+	u8 ampe_ie_len;
+	u8 *ampe_buf, *crypt = NULL;
+	size_t crypt_len;
+	const u8 *aad[] = { sta->addr, wpa_s->own_addr, cat };
+	const size_t aad_len[] = { ETH_ALEN, ETH_ALEN,
+				   (elems->mic - 2) - cat };
+
+	if (!elems->mic || elems->mic_len < AES_BLOCK_SIZE) {
+		wpa_msg(wpa_s, MSG_DEBUG, "Mesh RSN: missing mic ie");
+		return -1;
+	}
+
+	ampe_buf = (u8 *) elems->mic + elems->mic_len;
+	if ((int) elems_len < ampe_buf - start)
+		return -1;
+
+	crypt_len = elems_len - (elems->mic - start);
+	if (crypt_len < 2) {
+		wpa_msg(wpa_s, MSG_DEBUG, "Mesh RSN: missing ampe ie");
+		return -1;
+	}
+
+	/* crypt is modified by siv_decrypt */
+	crypt = os_zalloc(crypt_len);
+	if (!crypt) {
+		wpa_printf(MSG_ERROR, "Mesh RSN: out of memory");
+		ret = -ENOMEM;
+		goto free;
+	}
+
+	os_memcpy(crypt, elems->mic, crypt_len);
+
+	if (aes_siv_decrypt(sta->aek, crypt, crypt_len, 3,
+			    aad, aad_len, ampe_buf)) {
+		wpa_printf(MSG_ERROR, "Mesh RSN: frame verification failed!");
+		ret = -1;
+		goto free;
+	}
+
+	ampe_eid = *ampe_buf++;
+	ampe_ie_len = *ampe_buf++;
+
+	if (ampe_eid != WLAN_EID_AMPE ||
+	    ampe_ie_len < sizeof(struct ieee80211_ampe_ie)) {
+		wpa_msg(wpa_s, MSG_DEBUG, "Mesh RSN: invalid ampe ie");
+		ret = -1;
+		goto free;
+	}
+
+	ampe = (struct ieee80211_ampe_ie *) ampe_buf;
+	if (os_memcmp(ampe->peer_nonce, null_nonce, 32) != 0 &&
+	    os_memcmp(ampe->peer_nonce, sta->my_nonce, 32) != 0) {
+		wpa_msg(wpa_s, MSG_DEBUG, "Mesh RSN: invalid peer nonce");
+		ret = -1;
+		goto free;
+	}
+	os_memcpy(sta->peer_nonce, ampe->local_nonce,
+		  sizeof(ampe->local_nonce));
+	os_memcpy(sta->mgtk, ampe->mgtk, sizeof(ampe->mgtk));
+
+	/* todo parse mgtk expiration */
+free:
+	os_free(crypt);
+	return ret;
+}

wpa_supplicant/mesh_rsn.h

@@ -0,0 +1,35 @@
+/*
+ * WPA Supplicant - Mesh RSN routines
+ * Copyright (c) 2013-2014, cozybit, Inc.  All rights reserved.
+ *
+ * This software may be distributed under the terms of the BSD license.
+ * See README for more details.
+ */
+
+#ifndef MESH_RSN_H
+#define MESH_RSN_H
+
+struct mesh_rsn {
+	struct wpa_supplicant *wpa_s;
+	struct wpa_authenticator *auth;
+	u8 mgtk[16];
+#ifdef CONFIG_SAE
+	struct wpabuf *sae_token;
+	int sae_group_index;
+#endif /* CONFIG_SAE */
+};
+
+struct mesh_rsn * mesh_rsn_auth_init(struct wpa_supplicant *wpa_s,
+				     struct mesh_conf *conf);
+int mesh_rsn_auth_sae_sta(struct wpa_supplicant *wpa_s, struct sta_info *sta);
+int mesh_rsn_derive_mtk(struct wpa_supplicant *wpa_s, struct sta_info *sta);
+void mesh_rsn_get_pmkid(struct mesh_rsn *rsn, struct sta_info *sta, u8 *pmkid);
+void mesh_rsn_init_ampe_sta(struct wpa_supplicant *wpa_s,
+			    struct sta_info *sta);
+int mesh_rsn_protect_frame(struct mesh_rsn *rsn, struct sta_info *sta,
+			   const u8 *cat, struct wpabuf *buf);
+int mesh_rsn_process_ampe(struct wpa_supplicant *wpa_s, struct sta_info *sta,
+			  struct ieee802_11_elems *elems, const u8 *cat,
+			  const u8 *start, size_t elems_len);
+
+#endif /* MESH_RSN_H */

wpa_supplicant/wpa_supplicant_i.h

@@ -668,6 +668,9 @@ struct wpa_supplicant {
 #endif /* CONFIG_AP */
 
 	struct hostapd_iface *ifmsh;
+#ifdef CONFIG_MESH
+	struct mesh_rsn *mesh_rsn;
+#endif /* CONFIG_MESH */
 
 	unsigned int off_channel_freq;
 	struct wpabuf *pending_action_tx;