975b7a02cb
This is helpful in being able to get the functionality needed for SAE into a separate library (libpasn.so) without needing all of the ieee802_11.c functionality. Signed-off-by: Jouni Malinen <quic_jouni@quicinc.com>
139 lines
3.4 KiB
C
139 lines
3.4 KiB
C
/*
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* hostapd / Comeback token mechanism for SAE
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* Copyright (c) 2002-2017, Jouni Malinen <j@w1.fi>
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*
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* This software may be distributed under the terms of the BSD license.
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* See README for more details.
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*/
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#include "utils/includes.h"
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#include "utils/common.h"
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#include "hostapd.h"
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#include "crypto/sha256.h"
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#include "crypto/random.h"
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#include "common/ieee802_11_defs.h"
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#include "comeback_token.h"
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#if defined(CONFIG_SAE) || defined(CONFIG_PASN)
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static int comeback_token_hash(const u8 *comeback_key, const u8 *addr, u8 *idx)
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{
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u8 hash[SHA256_MAC_LEN];
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if (hmac_sha256(comeback_key, COMEBACK_KEY_SIZE,
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addr, ETH_ALEN, hash) < 0)
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return -1;
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*idx = hash[0];
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return 0;
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}
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int check_comeback_token(const u8 *comeback_key,
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u16 *comeback_pending_idx, const u8 *addr,
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const u8 *token, size_t token_len)
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{
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u8 mac[SHA256_MAC_LEN];
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const u8 *addrs[2];
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size_t len[2];
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u16 token_idx;
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u8 idx;
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if (token_len != SHA256_MAC_LEN ||
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comeback_token_hash(comeback_key, addr, &idx) < 0)
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return -1;
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token_idx = comeback_pending_idx[idx];
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if (token_idx == 0 || token_idx != WPA_GET_BE16(token)) {
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wpa_printf(MSG_DEBUG,
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"Comeback: Invalid anti-clogging token from "
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MACSTR " - token_idx 0x%04x, expected 0x%04x",
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MAC2STR(addr), WPA_GET_BE16(token), token_idx);
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return -1;
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}
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addrs[0] = addr;
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len[0] = ETH_ALEN;
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addrs[1] = token;
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len[1] = 2;
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if (hmac_sha256_vector(comeback_key, COMEBACK_KEY_SIZE,
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2, addrs, len, mac) < 0 ||
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os_memcmp_const(token + 2, &mac[2], SHA256_MAC_LEN - 2) != 0)
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return -1;
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comeback_pending_idx[idx] = 0; /* invalidate used token */
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return 0;
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}
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struct wpabuf *
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auth_build_token_req(struct os_reltime *last_comeback_key_update,
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u8 *comeback_key, u16 comeback_idx,
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u16 *comeback_pending_idx, size_t idx_len,
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int group, const u8 *addr, int h2e)
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{
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struct wpabuf *buf;
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u8 *token;
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struct os_reltime now;
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u8 idx[2];
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const u8 *addrs[2];
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size_t len[2];
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u8 p_idx;
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u16 token_idx;
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os_get_reltime(&now);
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if (!os_reltime_initialized(last_comeback_key_update) ||
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os_reltime_expired(&now, last_comeback_key_update, 60) ||
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comeback_idx == 0xffff) {
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if (random_get_bytes(comeback_key, COMEBACK_KEY_SIZE) < 0)
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return NULL;
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wpa_hexdump(MSG_DEBUG, "Comeback: Updated token key",
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comeback_key, COMEBACK_KEY_SIZE);
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*last_comeback_key_update = now;
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comeback_idx = 0;
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os_memset(comeback_pending_idx, 0, idx_len);
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}
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buf = wpabuf_alloc(sizeof(le16) + 3 + SHA256_MAC_LEN);
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if (buf == NULL)
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return NULL;
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if (group)
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wpabuf_put_le16(buf, group); /* Finite Cyclic Group */
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if (h2e) {
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/* Encapsulate Anti-clogging Token field in a container IE */
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wpabuf_put_u8(buf, WLAN_EID_EXTENSION);
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wpabuf_put_u8(buf, 1 + SHA256_MAC_LEN);
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wpabuf_put_u8(buf, WLAN_EID_EXT_ANTI_CLOGGING_TOKEN);
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}
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if (comeback_token_hash(comeback_key, addr, &p_idx) < 0) {
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wpabuf_free(buf);
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return NULL;
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}
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token_idx = comeback_pending_idx[p_idx];
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if (!token_idx) {
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comeback_idx++;
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token_idx = comeback_idx;
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comeback_pending_idx[p_idx] = token_idx;
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}
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WPA_PUT_BE16(idx, token_idx);
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token = wpabuf_put(buf, SHA256_MAC_LEN);
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addrs[0] = addr;
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len[0] = ETH_ALEN;
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addrs[1] = idx;
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len[1] = sizeof(idx);
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if (hmac_sha256_vector(comeback_key, COMEBACK_KEY_SIZE,
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2, addrs, len, token) < 0) {
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wpabuf_free(buf);
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return NULL;
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}
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WPA_PUT_BE16(token, token_idx);
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return buf;
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}
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#endif /* defined(CONFIG_SAE) || defined(CONFIG_PASN) */
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