1126 lines
28 KiB
C
1126 lines
28 KiB
C
/*
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*
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* Wireless daemon for Linux
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*
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* Copyright (C) 2018-2019 Intel Corporation. All rights reserved.
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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*
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*/
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#ifdef HAVE_CONFIG_H
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#include <config.h>
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#endif
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#include <ell/ell.h>
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#include "src/missing.h"
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#include "src/util.h"
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#include "src/ie.h"
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#include "src/handshake.h"
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#include "src/crypto.h"
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#include "src/mpdu.h"
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#include "src/sae.h"
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#include "src/auth-proto.h"
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#define SAE_RETRANSMIT_TIMEOUT 2
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#define SAE_SYNC_MAX 3
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enum sae_state {
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SAE_STATE_NOTHING = 0,
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SAE_STATE_COMMITTED = 1,
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SAE_STATE_CONFIRMED = 2,
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SAE_STATE_ACCEPTED = 3,
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};
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struct sae_sm {
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struct auth_proto ap;
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struct handshake_state *handshake;
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struct l_ecc_point *pwe;
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enum sae_state state;
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const struct l_ecc_curve *curve;
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unsigned int group;
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uint8_t group_retry;
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const unsigned int *ecc_groups;
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struct l_ecc_scalar *rand;
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struct l_ecc_scalar *scalar;
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struct l_ecc_scalar *p_scalar;
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struct l_ecc_point *element;
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struct l_ecc_point *p_element;
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uint16_t send_confirm;
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uint8_t kck[32];
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uint8_t pmk[32];
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uint8_t pmkid[16];
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uint8_t *token;
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size_t token_len;
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/* number of state resyncs that have occurred */
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uint16_t sync;
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/* number of SAE confirm messages that have been sent */
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uint16_t sc;
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/* received value of the send-confirm counter */
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uint16_t rc;
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/* remote peer */
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uint8_t peer[6];
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sae_tx_authenticate_func_t tx_auth;
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sae_tx_associate_func_t tx_assoc;
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void *user_data;
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};
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static bool sae_pwd_seed(const uint8_t *addr1, const uint8_t *addr2,
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uint8_t *base, size_t base_len,
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uint8_t counter, uint8_t *out)
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{
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uint8_t key[12];
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if (memcmp(addr1, addr2, 6) > 0) {
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memcpy(key, addr1, 6);
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memcpy(key + 6, addr2, 6);
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} else {
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memcpy(key, addr2, 6);
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memcpy(key + 6, addr1, 6);
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}
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return hkdf_extract(L_CHECKSUM_SHA256, key, 12, 2, out, base, base_len,
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&counter, (size_t) 1);
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}
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static struct l_ecc_scalar *sae_pwd_value(const struct l_ecc_curve *curve,
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uint8_t *pwd_seed)
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{
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uint8_t pwd_value[L_ECC_SCALAR_MAX_BYTES];
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uint8_t prime[L_ECC_SCALAR_MAX_BYTES];
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ssize_t len;
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struct l_ecc_scalar *p = l_ecc_curve_get_prime(curve);
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len = l_ecc_scalar_get_data(p, prime, sizeof(prime));
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l_ecc_scalar_free(p);
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if (!kdf_sha256(pwd_seed, 32, "SAE Hunting and Pecking",
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strlen("SAE Hunting and Pecking"), prime, len,
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pwd_value, len))
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return NULL;
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return l_ecc_scalar_new(curve, pwd_value, sizeof(pwd_value));
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}
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/* IEEE 802.11-2016 - Section 12.4.2 Assumptions on SAE */
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static bool sae_cn(const uint8_t *kck, uint16_t send_confirm,
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struct l_ecc_scalar *scalar1,
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struct l_ecc_point *element1,
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struct l_ecc_scalar *scalar2,
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struct l_ecc_point *element2,
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uint8_t *confirm)
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{
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uint8_t s1[L_ECC_SCALAR_MAX_BYTES];
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uint8_t s2[L_ECC_SCALAR_MAX_BYTES];
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uint8_t e1[L_ECC_POINT_MAX_BYTES];
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uint8_t e2[L_ECC_POINT_MAX_BYTES];
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struct l_checksum *hmac;
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struct iovec iov[5];
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int ret;
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hmac = l_checksum_new_hmac(L_CHECKSUM_SHA256, kck, 32);
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if (!hmac)
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return false;
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iov[0].iov_base = &send_confirm;
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iov[0].iov_len = 2;
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iov[1].iov_base = (void *) s1;
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iov[1].iov_len = l_ecc_scalar_get_data(scalar1, s1, sizeof(s1));
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iov[2].iov_base = (void *) e1;
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iov[2].iov_len = l_ecc_point_get_data(element1, e1, sizeof(e1));
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iov[3].iov_base = (void *) s2;
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iov[3].iov_len = l_ecc_scalar_get_data(scalar2, s2, sizeof(s2));
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iov[4].iov_base = (void *) e2;
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iov[4].iov_len = l_ecc_point_get_data(element2, e2, sizeof(e2));
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l_checksum_updatev(hmac, iov, 5);
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ret = l_checksum_get_digest(hmac, confirm, 32);
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l_checksum_free(hmac);
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return (ret == 32);
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}
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static void sae_reject_authentication(struct sae_sm *sm, uint16_t reason)
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{
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uint8_t reject[6];
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uint8_t *ptr = reject;
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/* transaction */
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l_put_u16(1, ptr);
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ptr += 2;
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/* status success */
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l_put_u16(reason, ptr);
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ptr += 2;
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if (reason == MMPDU_STATUS_CODE_UNSUPP_FINITE_CYCLIC_GROUP) {
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l_put_u16(sm->group, ptr);
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ptr += 2;
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}
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sm->tx_auth(reject, ptr - reject, sm->user_data);
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}
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static struct l_ecc_scalar *sae_new_residue(const struct l_ecc_curve *curve,
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bool residue)
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{
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struct l_ecc_scalar *s = l_ecc_scalar_new_random(curve);
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while (l_ecc_scalar_legendre(s) != ((residue) ? -1 : 1)) {
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l_ecc_scalar_free(s);
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s = l_ecc_scalar_new_random(curve);
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}
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return s;
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}
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static bool sae_is_quadradic_residue(const struct l_ecc_curve *curve,
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struct l_ecc_scalar *value,
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struct l_ecc_scalar *qr,
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struct l_ecc_scalar *qnr)
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{
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uint64_t rbuf[L_ECC_MAX_DIGITS];
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struct l_ecc_scalar *y_sqr = l_ecc_scalar_new(curve, NULL, 0);
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struct l_ecc_scalar *r = l_ecc_scalar_new_random(curve);
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struct l_ecc_scalar *num = l_ecc_scalar_new(curve, NULL, 0);
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size_t bytes;
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l_ecc_scalar_sum_x(y_sqr, value);
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l_ecc_scalar_multiply(num, y_sqr, r);
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l_ecc_scalar_multiply(num, num, r);
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l_ecc_scalar_free(y_sqr);
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bytes = l_ecc_scalar_get_data(r, rbuf, sizeof(rbuf));
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l_ecc_scalar_free(r);
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if (bytes <= 0) {
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l_ecc_scalar_free(num);
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return false;
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}
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if (rbuf[bytes / 8 - 1] & 1) {
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l_ecc_scalar_multiply(num, num, qr);
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if (l_ecc_scalar_legendre(num) == -1) {
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l_ecc_scalar_free(num);
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return true;
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}
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} else {
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l_ecc_scalar_multiply(num, num, qnr);
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if (l_ecc_scalar_legendre(num) == 1) {
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l_ecc_scalar_free(num);
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return true;
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}
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}
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l_ecc_scalar_free(num);
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return false;
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}
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/*
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* IEEE 802.11-2016 Section 12.4.4.2.2
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* Generation of the password element with ECC groups
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*/
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static bool sae_compute_pwe(struct sae_sm *sm, char *password,
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const uint8_t *addr1, const uint8_t *addr2)
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{
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bool found = false;
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uint8_t counter;
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uint8_t pwd_seed[32];
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struct l_ecc_scalar *pwd_value;
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uint8_t random[32];
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uint8_t *base = (uint8_t *) password;
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size_t base_len = strlen(password);
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uint8_t save[32] = { 0 };
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struct l_ecc_scalar *qr;
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struct l_ecc_scalar *qnr;
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uint8_t x[L_ECC_SCALAR_MAX_BYTES];
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/* create qr/qnr prior to beginning hunting-and-pecking loop */
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qr = sae_new_residue(sm->curve, true);
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qnr = sae_new_residue(sm->curve, false);
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for (counter = 1; counter <= 20; counter++) {
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/* pwd-seed = H(max(addr1, addr2) || min(addr1, addr2),
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* base || counter)
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* pwd-value = KDF-256(pwd-seed, "SAE Hunting and Pecking", p)
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*/
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sae_pwd_seed(addr1, addr2, base, base_len, counter, pwd_seed);
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pwd_value = sae_pwd_value(sm->curve, pwd_seed);
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if (!pwd_value)
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continue;
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if (sae_is_quadradic_residue(sm->curve, pwd_value, qr, qnr)) {
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if (found == false) {
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l_ecc_scalar_get_data(pwd_value, x, sizeof(x));
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memcpy(save, pwd_seed, 32);
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l_getrandom(random, 32);
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base = random;
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base_len = 32;
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found = true;
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}
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}
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l_ecc_scalar_free(pwd_value);
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}
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l_ecc_scalar_free(qr);
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l_ecc_scalar_free(qnr);
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if (!found) {
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l_error("max PWE iterations reached!");
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return false;
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}
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if (!(save[31] & 1))
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sm->pwe = l_ecc_point_from_data(sm->curve,
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L_ECC_POINT_TYPE_COMPRESSED_BIT1,
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x, sizeof(x));
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else
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sm->pwe = l_ecc_point_from_data(sm->curve,
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L_ECC_POINT_TYPE_COMPRESSED_BIT0,
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x, sizeof(x));
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if (!sm->pwe) {
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l_error("computing y failed, was x quadratic residue?");
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return false;
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}
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return true;
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}
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static bool sae_build_commit(struct sae_sm *sm, const uint8_t *addr1,
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const uint8_t *addr2, uint8_t *commit,
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size_t *len, bool retry)
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{
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struct l_ecc_scalar *mask;
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uint8_t *ptr = commit;
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struct l_ecc_scalar *order;
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if (retry)
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goto old_commit;
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if (!sm->handshake->passphrase) {
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l_error("no handshake passphrase found");
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return false;
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}
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if (!sae_compute_pwe(sm, sm->handshake->passphrase, addr1, addr2)) {
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l_error("could not compute PWE");
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return false;
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}
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sm->scalar = l_ecc_scalar_new(sm->curve, NULL, 0);
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sm->rand = l_ecc_scalar_new_random(sm->curve);
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mask = l_ecc_scalar_new_random(sm->curve);
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order = l_ecc_curve_get_order(sm->curve);
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/* commit-scalar = (rand + mask) mod r */
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l_ecc_scalar_add(sm->scalar, sm->rand, mask, order);
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l_ecc_scalar_free(order);
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/* commit-element = inv(mask * PWE) */
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sm->element = l_ecc_point_new(sm->curve);
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l_ecc_point_multiply(sm->element, mask, sm->pwe);
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l_ecc_point_inverse(sm->element);
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l_ecc_scalar_free(mask);
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/*
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* Several cases require retransmitting the same commit message. The
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* anti-clogging code path requires this as well as the retransmission
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* timeout.
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*/
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old_commit:
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/* transaction */
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l_put_le16(1, ptr);
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ptr += 2;
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/* status success */
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l_put_le16(0, ptr);
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ptr += 2;
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/* group */
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l_put_le16(sm->group, ptr);
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ptr += 2;
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if (sm->token) {
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memcpy(ptr, sm->token, sm->token_len);
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ptr += sm->token_len;
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}
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ptr += l_ecc_scalar_get_data(sm->scalar, ptr, L_ECC_SCALAR_MAX_BYTES);
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ptr += l_ecc_point_get_data(sm->element, ptr, L_ECC_POINT_MAX_BYTES);
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*len = ptr - commit;
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return true;
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}
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static void sae_send_confirm(struct sae_sm *sm)
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{
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uint8_t confirm[32];
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uint8_t body[38];
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uint8_t *ptr = body;
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/*
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* confirm = CN(KCK, send-confirm, commit-scalar, COMMIT-ELEMENT,
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* peer-commit-scalar, PEER-COMMIT-ELEMENT)
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*/
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sae_cn(sm->kck, sm->sc, sm->scalar, sm->element, sm->p_scalar,
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sm->p_element, confirm);
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l_put_le16(2, ptr);
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ptr += 2;
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l_put_le16(0, ptr);
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ptr += 2;
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l_put_le16(sm->sc, ptr);
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ptr += 2;
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memcpy(ptr, confirm, 32);
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ptr += 32;
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sm->state = SAE_STATE_CONFIRMED;
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sm->tx_auth(body, 38, sm->user_data);
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}
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|
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static int sae_process_commit(struct sae_sm *sm, const uint8_t *from,
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const uint8_t *frame, size_t len)
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{
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uint8_t *ptr = (uint8_t *) frame;
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uint8_t k[L_ECC_SCALAR_MAX_BYTES];
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struct l_ecc_point *k_point;
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uint8_t zero_key[32] = { 0 };
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uint8_t keyseed[32];
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uint8_t kck_and_pmk[2][32];
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uint8_t tmp[L_ECC_SCALAR_MAX_BYTES];
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struct l_ecc_scalar *tmp_scalar;
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uint16_t group;
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uint16_t reason = MMPDU_REASON_CODE_UNSPECIFIED;
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ssize_t klen;
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struct l_ecc_scalar *order;
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unsigned int nbytes = l_ecc_curve_get_scalar_bytes(sm->curve);
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|
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if (sm->state != SAE_STATE_COMMITTED) {
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l_error("bad state %u", sm->state);
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goto reject;
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}
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|
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/* Scalar + Point + group */
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if (len < nbytes + nbytes * 2 + 2) {
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l_error("bad packet length");
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goto reject;
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}
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|
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group = l_get_le16(ptr);
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ptr += 2;
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|
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if (group != sm->group) {
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sae_reject_authentication(sm,
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MMPDU_STATUS_CODE_UNSUPP_FINITE_CYCLIC_GROUP);
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return 0;
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}
|
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|
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sm->p_scalar = l_ecc_scalar_new(sm->curve, ptr, nbytes);
|
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if (!sm->p_scalar) {
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l_error("Server sent invalid P_Scalar during commit");
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reason = MMPDU_REASON_CODE_UNSPECIFIED;
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goto reject;
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}
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|
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ptr += nbytes;
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|
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sm->p_element = l_ecc_point_from_data(sm->curve, L_ECC_POINT_TYPE_FULL,
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ptr, nbytes * 2);
|
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if (!sm->p_element) {
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l_error("Server sent invalid P_Element during commit");
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reason = MMPDU_REASON_CODE_UNSPECIFIED;
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goto reject;
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}
|
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|
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if (l_ecc_scalars_are_equal(sm->p_scalar, sm->scalar) ||
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l_ecc_points_are_equal(sm->p_element, sm->element)) {
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/* possible reflection attack, silently discard message */
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l_warn("peer scalar or element matched own, discarding frame");
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|
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return 0;
|
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}
|
|
|
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sm->sc++;
|
|
|
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/*
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* K = scalar-op(rand, (element-op(scalar-op(peer-commit-scalar, PWE),
|
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* PEER-COMMIT-ELEMENT)))
|
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*/
|
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k_point = l_ecc_point_new(sm->curve);
|
|
|
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/* k_point = scalar-op(peer-commit-scalar, PWE) */
|
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l_ecc_point_multiply(k_point, sm->p_scalar, sm->pwe);
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|
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/* k_point = element-op(k_point, PEER-COMMIT-ELEMENT) */
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l_ecc_point_add(k_point, k_point, sm->p_element);
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|
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/* k_point = scalar-op(rand, k_point) */
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l_ecc_point_multiply(k_point, sm->rand, k_point);
|
|
|
|
/*
|
|
* IEEE 802.11-2016 - Section 12.4.4.2.1 ECC group definition
|
|
* ECC groups make use of a mapping function, F, that maps a
|
|
* point (x, y) that satisfies the curve equation to its x-coordinate—
|
|
* i.e., if P = (x, y) then F(P) = x.
|
|
*/
|
|
klen = l_ecc_point_get_x(k_point, k, sizeof(k));
|
|
|
|
l_ecc_point_free(k_point);
|
|
|
|
if (klen < 0)
|
|
goto reject;
|
|
|
|
/* keyseed = H(<0>32, k) */
|
|
hmac_sha256(zero_key, 32, k, klen, keyseed, 32);
|
|
|
|
/*
|
|
* kck_and_pmk = KDF-Hash-512(keyseed, "SAE KCK and PMK",
|
|
(commit-scalar + peer-commit-scalar) mod r)
|
|
*/
|
|
tmp_scalar = l_ecc_scalar_new(sm->curve, NULL, 0);
|
|
order = l_ecc_curve_get_order(sm->curve);
|
|
|
|
l_ecc_scalar_add(tmp_scalar, sm->p_scalar, sm->scalar, order);
|
|
l_ecc_scalar_get_data(tmp_scalar, tmp, sizeof(tmp));
|
|
|
|
kdf_sha256(keyseed, 32, "SAE KCK and PMK", strlen("SAE KCK and PMK"),
|
|
tmp, nbytes, kck_and_pmk, 64);
|
|
|
|
memcpy(sm->kck, kck_and_pmk[0], 32);
|
|
memcpy(sm->pmk, kck_and_pmk[1], 32);
|
|
|
|
/*
|
|
* PMKID = L((commit-scalar + peer-commit-scalar) mod r, 0, 128)
|
|
*/
|
|
l_ecc_scalar_add(tmp_scalar, sm->scalar, sm->p_scalar, order);
|
|
l_ecc_scalar_get_data(tmp_scalar, tmp, sizeof(tmp));
|
|
|
|
l_ecc_scalar_free(order);
|
|
|
|
l_ecc_scalar_free(tmp_scalar);
|
|
/* don't set the handshakes pmkid until confirm is verified */
|
|
memcpy(sm->pmkid, tmp, 16);
|
|
|
|
sae_send_confirm(sm);
|
|
|
|
return 0;
|
|
|
|
reject:
|
|
sae_reject_authentication(sm, reason);
|
|
return -EBADMSG;
|
|
}
|
|
|
|
static bool sae_verify_confirm(struct sae_sm *sm, const uint8_t *frame)
|
|
{
|
|
uint8_t check[32];
|
|
uint16_t rc = l_get_le16(frame);
|
|
|
|
sae_cn(sm->kck, rc, sm->p_scalar, sm->p_element, sm->scalar,
|
|
sm->element, check);
|
|
|
|
if (memcmp(frame + 2, check, 32)) {
|
|
l_error("confirm did not match");
|
|
return false;
|
|
}
|
|
|
|
sm->rc = rc;
|
|
|
|
return true;
|
|
}
|
|
|
|
static int sae_process_confirm(struct sae_sm *sm, const uint8_t *from,
|
|
const uint8_t *frame, size_t len)
|
|
{
|
|
const uint8_t *ptr = frame;
|
|
|
|
if (sm->state != SAE_STATE_CONFIRMED) {
|
|
l_error("bad state %u", sm->state);
|
|
goto reject;
|
|
}
|
|
|
|
if (len < 34) {
|
|
l_error("bad length");
|
|
goto reject;
|
|
}
|
|
|
|
if (!sae_verify_confirm(sm, ptr))
|
|
goto reject;
|
|
|
|
/* Sc shall be set to the value 2^16 - 1 */
|
|
sm->sc = 0xffff;
|
|
|
|
handshake_state_set_pmkid(sm->handshake, sm->pmkid);
|
|
handshake_state_set_pmk(sm->handshake, sm->pmk, 32);
|
|
|
|
sm->state = SAE_STATE_ACCEPTED;
|
|
|
|
sm->tx_assoc(sm->user_data);
|
|
|
|
return 0;
|
|
|
|
reject:
|
|
sae_reject_authentication(sm, MMPDU_REASON_CODE_UNSPECIFIED);
|
|
return -EBADMSG;
|
|
}
|
|
|
|
static bool sae_send_commit(struct sae_sm *sm, bool retry)
|
|
{
|
|
struct handshake_state *hs = sm->handshake;
|
|
/* regular commit + possible 256 byte token + 6 bytes header */
|
|
uint8_t commit[L_ECC_SCALAR_MAX_BYTES + L_ECC_POINT_MAX_BYTES + 262];
|
|
size_t len;
|
|
|
|
if (!sae_build_commit(sm, hs->spa, hs->aa, commit, &len, retry))
|
|
return false;
|
|
|
|
sm->state = SAE_STATE_COMMITTED;
|
|
|
|
sm->tx_auth(commit, len, sm->user_data);
|
|
|
|
return true;
|
|
}
|
|
|
|
static bool sae_timeout(struct auth_proto *ap)
|
|
{
|
|
struct sae_sm *sm = l_container_of(ap, struct sae_sm, ap);
|
|
|
|
/* regardless of state, reject if sync exceeds max */
|
|
if (sm->sync > SAE_SYNC_MAX) {
|
|
sae_reject_authentication(sm, MMPDU_REASON_CODE_UNSPECIFIED);
|
|
return false;
|
|
}
|
|
|
|
sm->sync++;
|
|
|
|
switch (sm->state) {
|
|
case SAE_STATE_COMMITTED:
|
|
sae_send_commit(sm, true);
|
|
break;
|
|
case SAE_STATE_CONFIRMED:
|
|
sm->sc++;
|
|
sae_send_confirm(sm);
|
|
break;
|
|
default:
|
|
/* should never happen */
|
|
l_error("SAE timeout in bad state %u", sm->state);
|
|
return false;
|
|
}
|
|
|
|
return true;
|
|
}
|
|
|
|
/*
|
|
* 802.11-2016 - Section 12.4.8.6.4
|
|
* If the Status code is ANTI_CLOGGING_TOKEN_REQUIRED, a new SAE Commit message
|
|
* shall be constructed with the Anti-Clogging Token from the received
|
|
* Authentication frame, and the commit-scalar and COMMIT-ELEMENT previously
|
|
* sent. The new SAE Commit message shall be transmitted to the peer, Sync shall
|
|
* be zeroed, and the t0 (retransmission) timer shall be set.
|
|
*/
|
|
static void sae_process_anti_clogging(struct sae_sm *sm, const uint8_t *ptr,
|
|
size_t len)
|
|
{
|
|
/*
|
|
* IEEE 802.11-2016 - Section 12.4.6 Anti-clogging tokens
|
|
*
|
|
* "It is suggested that an Anti-Clogging Token not exceed 256 octets"
|
|
*
|
|
* Also ensure the token is at least 1 byte. The packet passed in will
|
|
* contain the group number, meaning the anti-clogging token length is
|
|
* going to be 2 bytes less than the passed in length. This is why we
|
|
* are checking 3 > len > 258.
|
|
*/
|
|
if (len < 3 || len > 258) {
|
|
l_error("anti-clogging token size invalid %zu", len);
|
|
return;
|
|
}
|
|
|
|
sm->token = l_memdup(ptr + 2, len - 2);
|
|
sm->token_len = len - 2;
|
|
sm->sync = 0;
|
|
|
|
sae_send_commit(sm, true);
|
|
}
|
|
|
|
/*
|
|
* 802.11-2016 - 12.4.8.6.3 Protocol instance behavior - Nothing state
|
|
*/
|
|
static int sae_verify_nothing(struct sae_sm *sm, uint16_t transaction,
|
|
uint16_t status, const uint8_t *frame,
|
|
size_t len)
|
|
{
|
|
/*
|
|
* TODO: This does not handle the transition from NOTHING -> CONFIRMED
|
|
* as this is only relevant to the AP or in Mesh mode which is not
|
|
* yet supported.
|
|
*/
|
|
if (transaction != SAE_STATE_COMMITTED)
|
|
return -EBADMSG;
|
|
|
|
/* frame shall be silently discarded and Del event sent */
|
|
if (status != 0)
|
|
return -EBADMSG;
|
|
|
|
if (len < 2)
|
|
return -EBADMSG;
|
|
|
|
/* reject with unsupported group */
|
|
if (l_get_le16(frame) != sm->group) {
|
|
sae_reject_authentication(sm,
|
|
MMPDU_STATUS_CODE_UNSUPP_FINITE_CYCLIC_GROUP);
|
|
return -EBADMSG;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
static void sae_reset_state(struct sae_sm *sm)
|
|
{
|
|
l_free(sm->token);
|
|
sm->token = NULL;
|
|
|
|
l_ecc_scalar_free(sm->scalar);
|
|
sm->scalar = NULL;
|
|
l_ecc_scalar_free(sm->p_scalar);
|
|
sm->p_scalar = NULL;
|
|
l_ecc_scalar_free(sm->rand);
|
|
sm->rand = NULL;
|
|
l_ecc_point_free(sm->element);
|
|
sm->element = NULL;
|
|
l_ecc_point_free(sm->p_element);
|
|
sm->p_element = NULL;
|
|
l_ecc_point_free(sm->pwe);
|
|
sm->pwe = NULL;
|
|
}
|
|
|
|
/*
|
|
* 802.11-2016 - 12.4.8.6.4 Protocol instance behavior - Committed state
|
|
*/
|
|
static int sae_verify_committed(struct sae_sm *sm, uint16_t transaction,
|
|
uint16_t status, const uint8_t *frame,
|
|
size_t len)
|
|
{
|
|
/*
|
|
* Upon receipt of a Con event...
|
|
* Then the protocol instance checks the value of Sync. If it
|
|
* is greater than dot11RSNASAESync, the protocol instance shall send a
|
|
* Del event to the parent process and transition back to Nothing state.
|
|
* If Sync is not greater than dot11RSNASAESync, the protocol instance
|
|
* shall increment Sync, transmit the last SAE Commit message sent to
|
|
* the peer...
|
|
*/
|
|
if (transaction == SAE_STATE_CONFIRMED) {
|
|
if (sm->sync > SAE_SYNC_MAX)
|
|
return -EBADMSG;
|
|
|
|
sm->sync++;
|
|
|
|
sae_send_commit(sm, true);
|
|
|
|
return -EAGAIN;
|
|
}
|
|
|
|
switch (status) {
|
|
case MMPDU_STATUS_CODE_ANTI_CLOGGING_TOKEN_REQ:
|
|
sae_process_anti_clogging(sm, frame, len);
|
|
return -EAGAIN;
|
|
case MMPDU_STATUS_CODE_UNSUPP_FINITE_CYCLIC_GROUP:
|
|
/*
|
|
* TODO: hostapd in its current state does not include the
|
|
* group number as it should. This is a violation of the spec,
|
|
* but there isn't much we can do about it. We simply treat this
|
|
* response as if its rejecting our last commit message (which
|
|
* it most likely is). If/When this is fixed we should be
|
|
* checking that the group matches here, e.g.
|
|
*
|
|
* if (l_get_le16(frame) != sm->group)
|
|
* return false;
|
|
*
|
|
* According to 802.11 Section 12.4.8.6.4:
|
|
*
|
|
* "If the rejected group does not match the last offered group
|
|
* the protocol instance shall silently discard the message and
|
|
* set the t0 (retransmission) timer"
|
|
*/
|
|
if (len == 0)
|
|
l_warn("AP did not include group number in response!");
|
|
else if (len >= 2 && (l_get_le16(frame) != sm->group))
|
|
return -EBADMSG;
|
|
|
|
sm->group_retry++;
|
|
|
|
if (sm->ecc_groups[sm->group_retry] == 0) {
|
|
/*
|
|
* "If there are no other groups to choose, the protocol
|
|
* instance shall send a Del event to the parent process
|
|
* and transitions back to Nothing state"
|
|
*/
|
|
sm->state = SAE_STATE_NOTHING;
|
|
goto reject_unsupp_group;
|
|
}
|
|
|
|
/*
|
|
* "If the rejected group matches the last offered group, the
|
|
* protocol instance shall choose a different group and generate
|
|
* the PWE and the secret values according to 12.4.5.2; it then
|
|
* generates and transmits a new SAE Commit message to the peer,
|
|
* zeros Sync, sets the t0 (retransmission) timer, and remains
|
|
* in Committed state"
|
|
*/
|
|
|
|
sae_reset_state(sm);
|
|
|
|
sm->group = sm->ecc_groups[sm->group_retry];
|
|
sm->curve = l_ecc_curve_get_ike_group(sm->group);
|
|
|
|
sm->sync = 0;
|
|
|
|
sae_send_commit(sm, false);
|
|
|
|
return -EAGAIN;
|
|
case 0:
|
|
if (len < 2)
|
|
return -EBADMSG;
|
|
|
|
if (l_get_le16(frame) == sm->group)
|
|
return 0;
|
|
|
|
if (!l_ecc_curve_get_ike_group(l_get_le16(frame))) {
|
|
if (sm->sync > SAE_SYNC_MAX)
|
|
return -EBADMSG;
|
|
|
|
sm->sync++;
|
|
|
|
goto reject_unsupp_group;
|
|
}
|
|
|
|
/*
|
|
* If we get here we know that the groups do not match, but the
|
|
* group provided in the frame is supported. From section
|
|
* 12.4.8.6.4 we see:
|
|
*
|
|
* "If the group is supported but does not match that used when
|
|
* the protocol instance constructed its SAE Commit message,
|
|
* DiffGrp shall be set and the local identity and peer identity
|
|
* shall be checked"
|
|
*/
|
|
|
|
if (memcmp(sm->handshake->spa, sm->handshake->aa, 6) > 0) {
|
|
/*
|
|
* "The mesh STA, with the numerically greater of the two
|
|
* MAC addresses, drops the received SAE Commit message,
|
|
* retransmits its last SAE Commit message, and shall
|
|
* set the t0 (retransmission) timer and remain in
|
|
* Committed state"
|
|
*/
|
|
sae_send_commit(sm, true);
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* "The mesh STA, with the numerically lesser of the two
|
|
* MAC addresses, zeros Sync, shall increment Sc, choose
|
|
* the group from the received SAE Commit message,
|
|
* generate new PWE and new secret values according to
|
|
* 12.4.5.2, process the received SAE Commit message
|
|
* according to 12.4.5.4, generate a new SAE Commit
|
|
* message and SAE Confirm message, and shall transmit
|
|
* the new Commit and Confirm to the peer. It shall then
|
|
* transition to Confirmed state."
|
|
*/
|
|
sm->sync = 0;
|
|
sm->sc++;
|
|
sm->group = l_get_le16(frame);
|
|
sm->curve = l_ecc_curve_get_ike_group(sm->group);
|
|
|
|
sae_send_commit(sm, false);
|
|
|
|
sm->state = SAE_STATE_CONFIRMED;
|
|
|
|
/*
|
|
* The processing and sending of the confirm message
|
|
* will happen after we return. Since we have set the
|
|
* state to CONFIRMED, our confirm handler will get
|
|
* called.
|
|
*/
|
|
|
|
return 0;
|
|
default:
|
|
/*
|
|
* If the Status is some other nonzero value, the frame shall
|
|
* be silently discarded...
|
|
*/
|
|
return 0;
|
|
}
|
|
|
|
reject_unsupp_group:
|
|
sae_reject_authentication(sm,
|
|
MMPDU_STATUS_CODE_UNSUPP_FINITE_CYCLIC_GROUP);
|
|
return MMPDU_STATUS_CODE_UNSUPP_FINITE_CYCLIC_GROUP;
|
|
}
|
|
|
|
/*
|
|
* 802.11-2016 - 12.4.8.6.5 Protocol instance behavior - Confirmed state
|
|
*/
|
|
static int sae_verify_confirmed(struct sae_sm *sm, uint16_t trans,
|
|
uint16_t status, const uint8_t *frame,
|
|
size_t len)
|
|
{
|
|
if (trans == SAE_STATE_CONFIRMED)
|
|
return 0;
|
|
|
|
/*
|
|
* If the Status is nonzero, the frame shall be silently discarded...
|
|
*/
|
|
if (status != 0)
|
|
return 0;
|
|
|
|
/*
|
|
* If Sync is greater than dot11RSNASAESync, the protocol instance
|
|
* shall send the parent process a Del event and transitions back to
|
|
* Nothing state.
|
|
*/
|
|
if (sm->sync > SAE_SYNC_MAX)
|
|
return -EBADMSG;
|
|
|
|
if (len < 2)
|
|
return -EBADMSG;
|
|
|
|
/* frame shall be silently discarded */
|
|
if (l_get_le16(frame) != sm->group)
|
|
return 0;
|
|
|
|
/*
|
|
* the protocol instance shall increment Sync, increment Sc, and
|
|
* transmit its Commit and Confirm (with the new Sc value) messages.
|
|
*/
|
|
sm->sync++;
|
|
sm->sc++;
|
|
|
|
sae_send_commit(sm, true);
|
|
sae_send_confirm(sm);
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* 802.11-2016 - 12.4.8.6.6 Protocol instance behavior - Accepted state
|
|
*/
|
|
static int sae_verify_accepted(struct sae_sm *sm, uint16_t trans,
|
|
uint16_t status, const uint8_t *frame,
|
|
size_t len)
|
|
{
|
|
uint16_t sc;
|
|
|
|
/* spec does not specify what to do here, so print and discard */
|
|
if (trans != SAE_STATE_CONFIRMED) {
|
|
l_error("received transaction %u in accepted state", trans);
|
|
return -EBADMSG;
|
|
}
|
|
|
|
if (sm->sync > SAE_SYNC_MAX)
|
|
return -EBADMSG;
|
|
|
|
if (len < 2)
|
|
return -EBADMSG;
|
|
|
|
sc = l_get_le16(frame);
|
|
|
|
/*
|
|
* ... the value of send-confirm shall be checked. If the value is not
|
|
* greater than Rc or is equal to 2^16 - 1, the received frame shall be
|
|
* silently discarded.
|
|
*/
|
|
if (sc <= sm->rc || sc == 0xffff)
|
|
return -EBADMSG;
|
|
|
|
/*
|
|
* If the verification fails, the received frame shall be silently
|
|
* discarded.
|
|
*/
|
|
if (!sae_verify_confirm(sm, frame))
|
|
return -EBADMSG;
|
|
|
|
/*
|
|
* If the verification succeeds, the Rc variable shall be set to the
|
|
* send-confirm portion of the frame, the Sync shall be incremented and
|
|
* a new SAE Confirm message shall be constructed (with Sc set to
|
|
* 2^16 - 1) and sent to the peer.
|
|
*/
|
|
sm->sync++;
|
|
sm->sc = 0xffff;
|
|
|
|
sae_send_confirm(sm);
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int sae_verify_packet(struct sae_sm *sm, uint16_t trans,
|
|
uint16_t status, const uint8_t *frame,
|
|
size_t len)
|
|
{
|
|
if (trans != SAE_STATE_COMMITTED && trans != SAE_STATE_CONFIRMED)
|
|
return -EBADMSG;
|
|
|
|
switch (sm->state) {
|
|
case SAE_STATE_NOTHING:
|
|
return sae_verify_nothing(sm, trans, status, frame, len);
|
|
case SAE_STATE_COMMITTED:
|
|
return sae_verify_committed(sm, trans, status, frame, len);
|
|
case SAE_STATE_CONFIRMED:
|
|
return sae_verify_confirmed(sm, trans, status, frame, len);
|
|
case SAE_STATE_ACCEPTED:
|
|
return sae_verify_accepted(sm, trans, status, frame, len);
|
|
}
|
|
|
|
/* should never get here */
|
|
return -1;
|
|
}
|
|
|
|
static int sae_rx_authenticate(struct auth_proto *ap,
|
|
const uint8_t *frame, size_t len)
|
|
{
|
|
struct sae_sm *sm = l_container_of(ap, struct sae_sm, ap);
|
|
const struct mmpdu_header *hdr = mpdu_validate(frame, len);
|
|
const struct mmpdu_authentication *auth;
|
|
int ret;
|
|
|
|
if (!hdr) {
|
|
l_debug("Auth frame header did not validate");
|
|
goto reject;
|
|
}
|
|
|
|
auth = mmpdu_body(hdr);
|
|
|
|
len -= mmpdu_header_len(hdr);
|
|
|
|
ret = sae_verify_packet(sm, L_LE16_TO_CPU(auth->transaction_sequence),
|
|
L_LE16_TO_CPU(auth->status),
|
|
auth->ies, len - 6);
|
|
if (ret != 0)
|
|
return ret;
|
|
|
|
switch (L_LE16_TO_CPU(auth->transaction_sequence)) {
|
|
case SAE_STATE_COMMITTED:
|
|
return sae_process_commit(sm, hdr->address_2, auth->ies,
|
|
len - 6);
|
|
case SAE_STATE_CONFIRMED:
|
|
return sae_process_confirm(sm, hdr->address_2, auth->ies,
|
|
len - 6);
|
|
default:
|
|
l_error("invalid transaction sequence %u",
|
|
L_LE16_TO_CPU(auth->transaction_sequence));
|
|
}
|
|
|
|
reject:
|
|
sae_reject_authentication(sm, MMPDU_REASON_CODE_UNSPECIFIED);
|
|
|
|
return -EBADMSG;
|
|
}
|
|
|
|
static int sae_rx_associate(struct auth_proto *ap, const uint8_t *frame,
|
|
size_t len)
|
|
{
|
|
const struct mmpdu_header *mpdu = NULL;
|
|
const struct mmpdu_association_response *body;
|
|
|
|
mpdu = mpdu_validate(frame, len);
|
|
if (!mpdu) {
|
|
l_error("could not process frame");
|
|
return -EBADMSG;
|
|
}
|
|
|
|
body = mmpdu_body(mpdu);
|
|
|
|
if (body->status_code != 0)
|
|
return L_LE16_TO_CPU(body->status_code);
|
|
|
|
return 0;
|
|
}
|
|
|
|
static bool sae_start(struct auth_proto *ap)
|
|
{
|
|
struct sae_sm *sm = l_container_of(ap, struct sae_sm, ap);
|
|
|
|
if (sm->handshake->authenticator)
|
|
memcpy(sm->peer, sm->handshake->spa, 6);
|
|
else
|
|
memcpy(sm->peer, sm->handshake->aa, 6);
|
|
|
|
return sae_send_commit(sm, false);
|
|
}
|
|
|
|
static void sae_free(struct auth_proto *ap)
|
|
{
|
|
struct sae_sm *sm = l_container_of(ap, struct sae_sm, ap);
|
|
|
|
sae_reset_state(sm);
|
|
|
|
/* zero out whole structure, including keys */
|
|
explicit_bzero(sm, sizeof(struct sae_sm));
|
|
|
|
l_free(sm);
|
|
}
|
|
|
|
struct auth_proto *sae_sm_new(struct handshake_state *hs,
|
|
sae_tx_authenticate_func_t tx_auth,
|
|
sae_tx_associate_func_t tx_assoc,
|
|
void *user_data)
|
|
{
|
|
struct sae_sm *sm;
|
|
|
|
sm = l_new(struct sae_sm, 1);
|
|
|
|
if (!sm)
|
|
return NULL;
|
|
|
|
sm->tx_auth = tx_auth;
|
|
sm->tx_assoc = tx_assoc;
|
|
sm->user_data = user_data;
|
|
sm->handshake = hs;
|
|
sm->state = SAE_STATE_NOTHING;
|
|
sm->ecc_groups = l_ecc_curve_get_supported_ike_groups();
|
|
sm->group = sm->ecc_groups[sm->group_retry];
|
|
sm->curve = l_ecc_curve_get_ike_group(sm->group);
|
|
|
|
sm->ap.start = sae_start;
|
|
sm->ap.free = sae_free;
|
|
sm->ap.rx_authenticate = sae_rx_authenticate;
|
|
sm->ap.rx_associate = sae_rx_associate;
|
|
sm->ap.auth_timeout = sae_timeout;
|
|
|
|
return &sm->ap;
|
|
}
|