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* WPA Supplicant - RSN pre-authentication
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* Copyright (c) 2003-2007, Jouni Malinen <j@w1.fi>
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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* Alternatively, this software may be distributed under the terms of BSD
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* See README and COPYING for more details.
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#include "drivers/driver.h"
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#include "config_ssid.h"
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#include "l2_packet/l2_packet.h"
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#include "pmksa_cache.h"
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#define PMKID_CANDIDATE_PRIO_SCAN 1000
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struct rsn_pmksa_candidate {
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struct rsn_pmksa_candidate *next;
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* pmksa_candidate_free - Free all entries in PMKSA candidate list
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* @sm: Pointer to WPA state machine data from wpa_sm_init()
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void pmksa_candidate_free(struct wpa_sm *sm)
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struct rsn_pmksa_candidate *entry, *prev;
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entry = sm->pmksa_candidates;
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sm->pmksa_candidates = NULL;
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#if defined(IEEE8021X_EAPOL) && !defined(CONFIG_NO_WPA2)
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static void rsn_preauth_receive(void *ctx, const u8 *src_addr,
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const u8 *buf, size_t len)
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struct wpa_sm *sm = ctx;
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wpa_printf(MSG_DEBUG, "RX pre-auth from " MACSTR, MAC2STR(src_addr));
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wpa_hexdump(MSG_MSGDUMP, "RX pre-auth", buf, len);
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if (sm->preauth_eapol == NULL ||
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os_memcmp(sm->preauth_bssid, "\x00\x00\x00\x00\x00\x00",
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os_memcmp(sm->preauth_bssid, src_addr, ETH_ALEN) != 0) {
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wpa_printf(MSG_WARNING, "RSN pre-auth frame received from "
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"unexpected source " MACSTR " - dropped",
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eapol_sm_rx_eapol(sm->preauth_eapol, src_addr, buf, len);
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static void rsn_preauth_eapol_cb(struct eapol_sm *eapol, int success,
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struct wpa_sm *sm = ctx;
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res = eapol_sm_get_key(eapol, pmk, PMK_LEN);
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* EAP-LEAP is an exception from other EAP methods: it
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* uses only 16-byte PMK.
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res = eapol_sm_get_key(eapol, pmk, 16);
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wpa_hexdump_key(MSG_DEBUG, "RSN: PMK from pre-auth",
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sm->pmk_len = pmk_len;
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pmksa_cache_add(sm->pmksa, pmk, pmk_len,
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sm->preauth_bssid, sm->own_addr,
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wpa_msg(sm->ctx->ctx, MSG_INFO, "RSN: failed to get "
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"master session key from pre-auth EAPOL state "
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wpa_msg(sm->ctx->ctx, MSG_INFO, "RSN: pre-authentication with " MACSTR
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" %s", MAC2STR(sm->preauth_bssid),
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success ? "completed successfully" : "failed");
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rsn_preauth_deinit(sm);
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rsn_preauth_candidate_process(sm);
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static void rsn_preauth_timeout(void *eloop_ctx, void *timeout_ctx)
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struct wpa_sm *sm = eloop_ctx;
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wpa_msg(sm->ctx->ctx, MSG_INFO, "RSN: pre-authentication with " MACSTR
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" timed out", MAC2STR(sm->preauth_bssid));
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rsn_preauth_deinit(sm);
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rsn_preauth_candidate_process(sm);
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static int rsn_preauth_eapol_send(void *ctx, int type, const u8 *buf,
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struct wpa_sm *sm = ctx;
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/* TODO: could add l2_packet_sendmsg that allows fragments to avoid
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if (sm->l2_preauth == NULL)
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msg = wpa_sm_alloc_eapol(sm, type, buf, len, &msglen, NULL);
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wpa_hexdump(MSG_MSGDUMP, "TX EAPOL (preauth)", msg, msglen);
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res = l2_packet_send(sm->l2_preauth, sm->preauth_bssid,
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ETH_P_RSN_PREAUTH, msg, msglen);
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* rsn_preauth_init - Start new RSN pre-authentication
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* @sm: Pointer to WPA state machine data from wpa_sm_init()
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* @dst: Authenticator address (BSSID) with which to preauthenticate
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* @config: Current network configuration
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* Returns: 0 on success, -1 on another pre-authentication is in progress,
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* -2 on layer 2 packet initialization failure, -3 on EAPOL state machine
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* initialization failure, -4 on memory allocation failure
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* This function request an RSN pre-authentication with a given destination
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* address. This is usually called for PMKSA candidates found from scan results
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* or from driver reports. In addition, ctrl_iface PREAUTH command can trigger
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* pre-authentication.
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int rsn_preauth_init(struct wpa_sm *sm, const u8 *dst, struct wpa_ssid *config)
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struct eapol_config eapol_conf;
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struct eapol_ctx *ctx;
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if (sm->preauth_eapol)
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wpa_msg(sm->ctx->ctx, MSG_DEBUG, "RSN: starting pre-authentication "
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"with " MACSTR, MAC2STR(dst));
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sm->l2_preauth = l2_packet_init(sm->ifname, sm->own_addr,
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rsn_preauth_receive, sm, 0);
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if (sm->l2_preauth == NULL) {
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wpa_printf(MSG_WARNING, "RSN: Failed to initialize L2 packet "
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"processing for pre-authentication");
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if (sm->bridge_ifname) {
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sm->l2_preauth_br = l2_packet_init(sm->bridge_ifname,
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rsn_preauth_receive, sm, 0);
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if (sm->l2_preauth_br == NULL) {
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wpa_printf(MSG_WARNING, "RSN: Failed to initialize L2 "
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"packet processing (bridge) for "
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"pre-authentication");
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ctx = os_zalloc(sizeof(*ctx));
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wpa_printf(MSG_WARNING, "Failed to allocate EAPOL context.");
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ctx->ctx = sm->ctx->ctx;
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ctx->msg_ctx = sm->ctx->ctx;
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ctx->cb = rsn_preauth_eapol_cb;
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ctx->scard_ctx = sm->scard_ctx;
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ctx->eapol_send = rsn_preauth_eapol_send;
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ctx->eapol_send_ctx = sm;
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ctx->set_config_blob = sm->ctx->set_config_blob;
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ctx->get_config_blob = sm->ctx->get_config_blob;
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sm->preauth_eapol = eapol_sm_init(ctx);
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if (sm->preauth_eapol == NULL) {
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wpa_printf(MSG_WARNING, "RSN: Failed to initialize EAPOL "
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"state machines for pre-authentication");
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os_memset(&eapol_conf, 0, sizeof(eapol_conf));
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eapol_conf.accept_802_1x_keys = 0;
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eapol_conf.required_keys = 0;
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eapol_conf.fast_reauth = sm->fast_reauth;
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eapol_conf.workaround = config->eap_workaround;
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eapol_sm_notify_config(sm->preauth_eapol, config, &eapol_conf);
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* Use a shorter startPeriod with preauthentication since the first
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* preauth EAPOL-Start frame may end up being dropped due to race
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* condition in the AP between the data receive and key configuration
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* after the 4-Way Handshake.
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eapol_sm_configure(sm->preauth_eapol, -1, -1, 5, 6);
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os_memcpy(sm->preauth_bssid, dst, ETH_ALEN);
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eapol_sm_notify_portValid(sm->preauth_eapol, TRUE);
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/* 802.1X::portControl = Auto */
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eapol_sm_notify_portEnabled(sm->preauth_eapol, TRUE);
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eloop_register_timeout(sm->dot11RSNAConfigSATimeout, 0,
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rsn_preauth_timeout, sm, NULL);
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* rsn_preauth_deinit - Abort RSN pre-authentication
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* @sm: Pointer to WPA state machine data from wpa_sm_init()
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* This function aborts the current RSN pre-authentication (if one is started)
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* and frees resources allocated for it.
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void rsn_preauth_deinit(struct wpa_sm *sm)
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if (sm == NULL || !sm->preauth_eapol)
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eloop_cancel_timeout(rsn_preauth_timeout, sm, NULL);
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eapol_sm_deinit(sm->preauth_eapol);
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sm->preauth_eapol = NULL;
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os_memset(sm->preauth_bssid, 0, ETH_ALEN);
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l2_packet_deinit(sm->l2_preauth);
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sm->l2_preauth = NULL;
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if (sm->l2_preauth_br) {
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l2_packet_deinit(sm->l2_preauth_br);
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sm->l2_preauth_br = NULL;
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* rsn_preauth_candidate_process - Process PMKSA candidates
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* @sm: Pointer to WPA state machine data from wpa_sm_init()
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* Go through the PMKSA candidates and start pre-authentication if a candidate
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* without an existing PMKSA cache entry is found. Processed candidates will be
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* removed from the list.
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void rsn_preauth_candidate_process(struct wpa_sm *sm)
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struct rsn_pmksa_candidate *candidate;
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if (sm->pmksa_candidates == NULL)
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/* TODO: drop priority for old candidate entries */
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wpa_msg(sm->ctx->ctx, MSG_DEBUG, "RSN: processing PMKSA candidate "
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if (sm->preauth_eapol ||
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sm->proto != WPA_PROTO_RSN ||
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wpa_sm_get_state(sm) != WPA_COMPLETED ||
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sm->key_mgmt != WPA_KEY_MGMT_IEEE8021X) {
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wpa_msg(sm->ctx->ctx, MSG_DEBUG, "RSN: not in suitable state "
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"for new pre-authentication");
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return; /* invalid state for new pre-auth */
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while (sm->pmksa_candidates) {
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struct rsn_pmksa_cache_entry *p = NULL;
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candidate = sm->pmksa_candidates;
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p = pmksa_cache_get(sm->pmksa, candidate->bssid, NULL);
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if (os_memcmp(sm->bssid, candidate->bssid, ETH_ALEN) != 0 &&
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(p == NULL || p->opportunistic)) {
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wpa_msg(sm->ctx->ctx, MSG_DEBUG, "RSN: PMKSA "
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" selected for pre-authentication",
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MAC2STR(candidate->bssid));
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sm->pmksa_candidates = candidate->next;
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rsn_preauth_init(sm, candidate->bssid, sm->cur_ssid);
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wpa_msg(sm->ctx->ctx, MSG_DEBUG, "RSN: PMKSA candidate "
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MACSTR " does not need pre-authentication anymore",
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MAC2STR(candidate->bssid));
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/* Some drivers (e.g., NDIS) expect to get notified about the
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* PMKIDs again, so report the existing data now. */
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wpa_sm_add_pmkid(sm, candidate->bssid, p->pmkid);
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sm->pmksa_candidates = candidate->next;
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wpa_msg(sm->ctx->ctx, MSG_DEBUG, "RSN: no more pending PMKSA "
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* pmksa_candidate_add - Add a new PMKSA candidate
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* @sm: Pointer to WPA state machine data from wpa_sm_init()
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* @bssid: BSSID (authenticator address) of the candidate
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* @prio: Priority (the smaller number, the higher priority)
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* @preauth: Whether the candidate AP advertises support for pre-authentication
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* This function is used to add PMKSA candidates for RSN pre-authentication. It
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* is called from scan result processing and from driver events for PMKSA
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* candidates, i.e., EVENT_PMKID_CANDIDATE events to wpa_supplicant_event().
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void pmksa_candidate_add(struct wpa_sm *sm, const u8 *bssid,
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int prio, int preauth)
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struct rsn_pmksa_candidate *cand, *prev, *pos;
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if (sm->cur_ssid && sm->cur_ssid->proactive_key_caching)
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pmksa_cache_get_opportunistic(sm->pmksa, sm->cur_ssid, bssid);
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wpa_printf(MSG_DEBUG, "RSN: Ignored PMKID candidate without "
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/* If BSSID already on candidate list, update the priority of the old
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* entry. Do not override priority based on normal scan results. */
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cand = sm->pmksa_candidates;
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if (os_memcmp(cand->bssid, bssid, ETH_ALEN) == 0) {
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prev->next = cand->next;
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sm->pmksa_candidates = cand->next;
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if (prio < PMKID_CANDIDATE_PRIO_SCAN)
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cand->priority = prio;
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cand = os_zalloc(sizeof(*cand));
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os_memcpy(cand->bssid, bssid, ETH_ALEN);
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cand->priority = prio;
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/* Add candidate to the list; order by increasing priority value. i.e.,
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* highest priority (smallest value) first. */
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pos = sm->pmksa_candidates;
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if (cand->priority <= pos->priority)
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sm->pmksa_candidates = cand;
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wpa_msg(sm->ctx->ctx, MSG_DEBUG, "RSN: added PMKSA cache "
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"candidate " MACSTR " prio %d", MAC2STR(bssid), prio);
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rsn_preauth_candidate_process(sm);
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/* TODO: schedule periodic scans if current AP supports preauth */
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* rsn_preauth_scan_results - Process scan results to find PMKSA candidates
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* @sm: Pointer to WPA state machine data from wpa_sm_init()
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* @results: Scan results
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* @count: Number of BSSes in scan results
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* This functions goes through the scan results and adds all suitable APs
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* (Authenticators) into PMKSA candidate list.
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void rsn_preauth_scan_results(struct wpa_sm *sm,
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struct wpa_scan_result *results, int count)
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struct wpa_scan_result *r;
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struct wpa_ie_data ie;
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struct rsn_pmksa_cache_entry *pmksa;
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if (sm->cur_ssid == NULL)
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* TODO: is it ok to free all candidates? What about the entries
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* received from EVENT_PMKID_CANDIDATE?
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pmksa_candidate_free(sm);
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for (i = count - 1; i >= 0; i--) {
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if (r->ssid_len != sm->cur_ssid->ssid_len ||
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os_memcmp(r->ssid, sm->cur_ssid->ssid,
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if (os_memcmp(r->bssid, sm->bssid, ETH_ALEN) == 0)
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if (r->rsn_ie_len == 0 ||
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wpa_parse_wpa_ie(r->rsn_ie, r->rsn_ie_len, &ie))
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pmksa = pmksa_cache_get(sm->pmksa, r->bssid, NULL);
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(!pmksa->opportunistic ||
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!(ie.capabilities & WPA_CAPABILITY_PREAUTH)))
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* Give less priority to candidates found from normal
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pmksa_candidate_add(sm, r->bssid,
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PMKID_CANDIDATE_PRIO_SCAN,
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ie.capabilities & WPA_CAPABILITY_PREAUTH);
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#ifdef CONFIG_CTRL_IFACE
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* rsn_preauth_get_status - Get pre-authentication status
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* @sm: Pointer to WPA state machine data from wpa_sm_init()
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* @buf: Buffer for status information
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* @buflen: Maximum buffer length
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* @verbose: Whether to include verbose status information
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* Returns: Number of bytes written to buf.
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* Query WPA2 pre-authentication for status information. This function fills in
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* a text area with current status information. If the buffer (buf) is not
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* large enough, status information will be truncated to fit the buffer.
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int rsn_preauth_get_status(struct wpa_sm *sm, char *buf, size_t buflen,
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char *pos = buf, *end = buf + buflen;
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if (sm->preauth_eapol) {
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ret = os_snprintf(pos, end - pos, "Pre-authentication "
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"EAPOL state machines:\n");
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if (ret < 0 || ret >= end - pos)
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res = eapol_sm_get_status(sm->preauth_eapol,
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pos, end - pos, verbose);
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#endif /* CONFIG_CTRL_IFACE */
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* rsn_preauth_in_progress - Verify whether pre-authentication is in progress
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* @sm: Pointer to WPA state machine data from wpa_sm_init()
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int rsn_preauth_in_progress(struct wpa_sm *sm)
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return sm->preauth_eapol != NULL;
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#endif /* IEEE8021X_EAPOL and !CONFIG_NO_WPA2 */
added
removed
src/rsn_supp/preauth.c
