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https://github.com/vanhoefm/fragattacks.git
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FILS: Decrypt Association Request elements and check Key-Auth (AP)
Signed-off-by: Jouni Malinen <jouni@qca.qualcomm.com>
This commit is contained in:
Jouni Malinen
Jouni Malinen
parent
86cd6928e0
commit
78815f3dde
@ -2366,6 +2366,7 @@ static void handle_assoc(struct hostapd_data *hapd,
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const u8 *pos;
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int left, i;
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struct sta_info *sta;
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u8 *tmp = NULL;
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if (len < IEEE80211_HDRLEN + (reassoc ? sizeof(mgmt->u.reassoc_req) :
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sizeof(mgmt->u.assoc_req))) {
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@ -2491,6 +2492,30 @@ static void handle_assoc(struct hostapd_data *hapd,
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*/
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sta->capability = capab_info;
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#ifdef CONFIG_FILS
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if (sta->auth_alg == WLAN_AUTH_FILS_SK ||
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sta->auth_alg == WLAN_AUTH_FILS_SK_PFS ||
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sta->auth_alg == WLAN_AUTH_FILS_PK) {
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/* The end of the payload is encrypted. Need to decrypt it
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* before parsing. */
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tmp = os_malloc(left);
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if (!tmp) {
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resp = WLAN_STATUS_UNSPECIFIED_FAILURE;
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goto fail;
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}
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os_memcpy(tmp, pos, left);
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left = fils_decrypt_assoc(sta->wpa_sm, sta->fils_session, mgmt,
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len, tmp, left);
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if (left < 0) {
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resp = WLAN_STATUS_UNSPECIFIED_FAILURE;
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goto fail;
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}
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pos = tmp;
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}
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#endif /* CONFIG_FILS */
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/* followed by SSID and Supported rates; and HT capabilities if 802.11n
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* is used */
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resp = check_assoc_ies(hapd, sta, pos, left, reassoc);
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@ -2600,6 +2625,7 @@ static void handle_assoc(struct hostapd_data *hapd,
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resp = WLAN_STATUS_AP_UNABLE_TO_HANDLE_NEW_STA;
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reply_res = send_assoc_resp(hapd, sta, resp, reassoc, pos, left);
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os_free(tmp);
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/*
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* Remove the station in case tranmission of a success response fails
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@ -1747,6 +1747,10 @@ int wpa_auth_sm_event(struct wpa_state_machine *sm, enum wpa_event event)
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if (sm->mgmt_frame_prot && event == WPA_AUTH)
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remove_ptk = 0;
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#endif /* CONFIG_IEEE80211W */
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#ifdef CONFIG_FILS
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if (wpa_key_mgmt_fils(sm->wpa_key_mgmt) && event == WPA_AUTH)
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remove_ptk = 0;
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#endif /* CONFIG_FILS */
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if (remove_ptk) {
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sm->PTK_valid = FALSE;
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@ -2057,6 +2061,11 @@ int fils_auth_pmk_to_ptk(struct wpa_state_machine *sm, const u8 *pmk,
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sm->fils_key_auth_ap,
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&sm->fils_key_auth_len);
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os_memset(ick, 0, sizeof(ick));
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/* Store nonces for (Re)Association Request/Response frame processing */
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os_memcpy(sm->SNonce, snonce, FILS_NONCE_LEN);
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os_memcpy(sm->ANonce, anonce, FILS_NONCE_LEN);
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return res;
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}
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@ -2114,6 +2123,138 @@ static int wpa_aead_decrypt(struct wpa_state_machine *sm, struct wpa_ptk *ptk,
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*_key_data_len = key_data_len;
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return 0;
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}
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int fils_decrypt_assoc(struct wpa_state_machine *sm, const u8 *fils_session,
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const struct ieee80211_mgmt *mgmt, size_t frame_len,
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u8 *pos, size_t left)
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{
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u16 fc, stype;
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const u8 *end, *ie_start, *ie, *session, *crypt;
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struct ieee802_11_elems elems;
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const u8 *aad[5];
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size_t aad_len[5];
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if (!sm || !sm->PTK_valid) {
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wpa_printf(MSG_DEBUG,
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"FILS: No KEK to decrypt Assocication Request frame");
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return -1;
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}
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if (!wpa_key_mgmt_fils(sm->wpa_key_mgmt)) {
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wpa_printf(MSG_DEBUG,
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"FILS: Not a FILS AKM - reject association");
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return -1;
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}
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end = ((const u8 *) mgmt) + frame_len;
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fc = le_to_host16(mgmt->frame_control);
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stype = WLAN_FC_GET_STYPE(fc);
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if (stype == WLAN_FC_STYPE_REASSOC_REQ)
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ie_start = mgmt->u.reassoc_req.variable;
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else
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ie_start = mgmt->u.assoc_req.variable;
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ie = ie_start;
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/*
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* Find FILS Session element which is the last unencrypted element in
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* the frame.
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*/
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session = NULL;
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while (ie + 1 < end) {
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if (ie + 2 + ie[1] > end)
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break;
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if (ie[0] == WLAN_EID_EXTENSION &&
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ie[1] >= 1 + FILS_SESSION_LEN &&
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ie[2] == WLAN_EID_EXT_FILS_SESSION) {
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session = ie;
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break;
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}
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ie += 2 + ie[1];
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}
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if (!session) {
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wpa_printf(MSG_DEBUG,
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"FILS: Could not find FILS Session element in Association Request frame - reject");
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return -1;
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}
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if (os_memcmp(fils_session, session + 3, FILS_SESSION_LEN) != 0) {
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wpa_printf(MSG_DEBUG, "FILS: Session mismatch");
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wpa_hexdump(MSG_DEBUG, "FILS: Expected FILS Session",
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fils_session, FILS_SESSION_LEN);
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wpa_hexdump(MSG_DEBUG, "FILS: Received FILS Session",
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session + 3, FILS_SESSION_LEN);
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return -1;
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}
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crypt = session + 2 + session[1];
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if (end - crypt < AES_BLOCK_SIZE) {
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wpa_printf(MSG_DEBUG,
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"FILS: Too short frame to include AES-SIV data");
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return -1;
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}
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/* AES-SIV AAD vectors */
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/* The STA's MAC address */
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aad[0] = mgmt->sa;
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aad_len[0] = ETH_ALEN;
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/* The AP's BSSID */
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aad[1] = mgmt->da;
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aad_len[1] = ETH_ALEN;
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/* The STA's nonce */
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aad[2] = sm->SNonce;
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aad_len[2] = FILS_NONCE_LEN;
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/* The AP's nonce */
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aad[3] = sm->ANonce;
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aad_len[3] = FILS_NONCE_LEN;
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/*
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* The (Re)Association Request frame from the Capability Information
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* field to the FILS Session element (both inclusive).
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*/
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aad[4] = (const u8 *) &mgmt->u.assoc_req.capab_info;
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aad_len[4] = crypt - aad[0];
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if (aes_siv_decrypt(sm->PTK.kek, sm->PTK.kek_len, crypt, end - crypt,
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1, aad, aad_len, pos + (crypt - ie_start)) < 0) {
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wpa_printf(MSG_DEBUG,
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"FILS: Invalid AES-SIV data in the frame");
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return -1;
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}
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wpa_hexdump(MSG_DEBUG, "FILS: Decrypted Association Request elements",
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pos, left - AES_BLOCK_SIZE);
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if (ieee802_11_parse_elems(pos, left - AES_BLOCK_SIZE, &elems, 1) ==
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ParseFailed) {
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wpa_printf(MSG_DEBUG,
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"FILS: Failed to parse decrypted elements");
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return -1;
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}
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if (!elems.fils_key_confirm) {
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wpa_printf(MSG_DEBUG, "FILS: No FILS Key Confirm element");
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return -1;
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}
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if (elems.fils_key_confirm_len != sm->fils_key_auth_len) {
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wpa_printf(MSG_DEBUG,
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"FILS: Unexpected Key-Auth length %d (expected %d)",
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elems.fils_key_confirm_len,
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(int) sm->fils_key_auth_len);
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return -1;
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}
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if (os_memcmp(elems.fils_key_confirm, sm->fils_key_auth_sta,
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sm->fils_key_auth_len) != 0) {
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wpa_printf(MSG_DEBUG, "FILS: Key-Auth mismatch");
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wpa_hexdump(MSG_DEBUG, "FILS: Received Key-Auth",
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elems.fils_key_confirm,
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elems.fils_key_confirm_len);
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wpa_hexdump(MSG_DEBUG, "FILS: Expected Key-Auth",
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sm->fils_key_auth_sta, sm->fils_key_auth_len);
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return -1;
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}
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return left - AES_BLOCK_SIZE;
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}
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#endif /* CONFIG_FILS */
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@ -350,5 +350,8 @@ int wpa_auth_ensure_group(struct wpa_authenticator *wpa_auth, int vlan_id);
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int wpa_auth_release_group(struct wpa_authenticator *wpa_auth, int vlan_id);
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int fils_auth_pmk_to_ptk(struct wpa_state_machine *sm, const u8 *pmk,
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size_t pmk_len, const u8 *snonce, const u8 *anonce);
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int fils_decrypt_assoc(struct wpa_state_machine *sm, const u8 *fils_session,
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const struct ieee80211_mgmt *mgmt, size_t frame_len,
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u8 *pos, size_t left);
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#endif /* WPA_AUTH_H */
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