eapol: moved AP authenticator into eapol
Includes: - support for handling ptk 2/4 and 4/4. Also sending 1/4 and 3/4. - new API to register an authenticator SM. This automatically sends 1/4 to kick off authentication with an sta.
This commit is contained in:
James Prestwood
Denis Kenzior
parent
b81a9482b4
commit
9d4f1b4ca6
332
src/eapol.c
332
src/eapol.c
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@ -356,6 +356,9 @@ bool eapol_verify_ptk_2_of_4(const struct eapol_key *ek)
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if (ek->wpa_key_id)
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return false;
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if (ek->request)
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return false;
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key_len = L_BE16_TO_CPU(ek->key_length);
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if (key_len != 0)
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return false;
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@ -439,6 +442,9 @@ bool eapol_verify_ptk_4_of_4(const struct eapol_key *ek, bool is_wpa)
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if (ek->wpa_key_id)
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return false;
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if (ek->request)
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return false;
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key_len = L_BE16_TO_CPU(ek->key_length);
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if (key_len != 0)
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return false;
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@ -656,11 +662,14 @@ struct eapol_sm {
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void *user_data;
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struct l_timeout *timeout;
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struct l_timeout *eapol_start_timeout;
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unsigned int frame_retry;
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uint16_t listen_interval;
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bool have_replay:1;
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bool started:1;
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bool use_eapol_start:1;
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bool require_handshake:1;
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bool eap_exchanged:1;
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bool authenticator:1;
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struct eap_state *eap;
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struct eapol_frame *early_frame;
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uint32_t watch_id;
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@ -721,6 +730,11 @@ void eapol_sm_set_protocol_version(struct eapol_sm *sm,
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sm->protocol_version = protocol_version;
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}
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void eapol_sm_set_listen_interval(struct eapol_sm *sm, uint16_t interval)
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{
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sm->listen_interval = interval;
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}
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void eapol_sm_set_user_data(struct eapol_sm *sm, void *user_data)
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{
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sm->user_data = user_data;
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@ -816,6 +830,97 @@ static void send_eapol_start(struct l_timeout *timeout, void *user_data)
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eapol_sm_write(sm, frame, false);
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}
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static void eapol_set_key_timeout(struct eapol_sm *sm,
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l_timeout_notify_cb_t cb)
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{
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/*
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* 802.11-2016 12.7.6.6: "The retransmit timeout value shall be
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* 100 ms for the first timeout, half the listen interval for the
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* second timeout, and the listen interval for subsequent timeouts.
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* If there is no listen interval or the listen interval is zero,
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* then 100 ms shall be used for all timeout values."
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*/
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unsigned int timeout_ms = 100;
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unsigned int beacon_us = 100 * 1024;
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sm->frame_retry++;
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if (sm->frame_retry == 2 &&
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sm->listen_interval != 0)
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timeout_ms = sm->listen_interval * beacon_us / 2000;
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else if (sm->frame_retry > 2 &&
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sm->listen_interval != 0)
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timeout_ms = sm->listen_interval * beacon_us / 1000;
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if (sm->frame_retry > 1)
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l_timeout_modify_ms(sm->timeout, timeout_ms);
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else {
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if (sm->timeout)
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l_timeout_remove(sm->timeout);
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sm->timeout = l_timeout_create_ms(timeout_ms, cb, sm,
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NULL);
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}
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}
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/* 802.11-2016 Section 12.7.6.2 */
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static void eapol_send_ptk_1_of_4(struct eapol_sm *sm)
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{
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uint32_t ifindex = sm->handshake->ifindex;
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const uint8_t *aa = sm->handshake->aa;
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uint8_t frame_buf[512];
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struct eapol_key *ek = (struct eapol_key *) frame_buf;
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enum crypto_cipher cipher = ie_rsn_cipher_suite_to_cipher(
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sm->handshake->pairwise_cipher);
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uint8_t pmkid[16];
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handshake_state_new_anonce(sm->handshake);
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sm->handshake->ptk_complete = false;
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sm->replay_counter++;
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memset(ek, 0, sizeof(struct eapol_key));
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ek->header.protocol_version = sm->protocol_version;
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ek->header.packet_type = 0x3;
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ek->descriptor_type = EAPOL_DESCRIPTOR_TYPE_80211;
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/* Must be HMAC-SHA1-128 + AES when using CCMP with PSK or 8021X */
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ek->key_descriptor_version = EAPOL_KEY_DESCRIPTOR_VERSION_HMAC_SHA1_AES;
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ek->key_type = true;
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ek->key_ack = true;
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ek->key_length = L_CPU_TO_BE16(crypto_cipher_key_len(cipher));
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ek->key_replay_counter = L_CPU_TO_BE64(sm->replay_counter);
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memcpy(ek->key_nonce, sm->handshake->anonce, sizeof(ek->key_nonce));
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/* Write the PMKID KDE into Key Data field unencrypted */
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crypto_derive_pmkid(sm->handshake->pmk, sm->handshake->spa, aa,
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pmkid, false);
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eapol_key_data_append(ek, HANDSHAKE_KDE_PMKID, pmkid, 16);
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ek->header.packet_len = L_CPU_TO_BE16(sizeof(struct eapol_key) +
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L_BE16_TO_CPU(ek->key_data_len) - 4);
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l_debug("STA: "MAC" retries=%u", MAC_STR(sm->handshake->spa),
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sm->frame_retry);
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__eapol_tx_packet(ifindex, sm->handshake->spa, ETH_P_PAE,
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(struct eapol_frame *) ek, false);
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}
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static void eapol_ptk_1_of_4_retry(struct l_timeout *timeout, void *user_data)
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{
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struct eapol_sm *sm = user_data;
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if (sm->frame_retry >= 3) {
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handshake_failed(sm, MMPDU_REASON_CODE_4WAY_HANDSHAKE_TIMEOUT);
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return;
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}
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eapol_send_ptk_1_of_4(sm);
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eapol_set_key_timeout(sm, eapol_ptk_1_of_4_retry);
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}
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static void eapol_handle_ptk_1_of_4(struct eapol_sm *sm,
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const struct eapol_key *ek)
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{
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@ -828,6 +933,8 @@ static void eapol_handle_ptk_1_of_4(struct eapol_sm *sm,
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const uint8_t *pmkid;
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struct ie_rsn_info rsn_info;
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l_debug("ifindex=%u", sm->handshake->ifindex);
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if (!eapol_verify_ptk_1_of_4(ek))
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goto error_unspecified;
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@ -953,6 +1060,144 @@ error_unspecified:
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handshake_failed(sm, MMPDU_REASON_CODE_UNSPECIFIED);
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}
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#define EAPOL_PAIRWISE_UPDATE_COUNT 3
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/* 802.11-2016 Section 12.7.6.4 */
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static void eapol_send_ptk_3_of_4(struct eapol_sm *sm)
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{
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uint32_t ifindex = sm->handshake->ifindex;
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uint8_t frame_buf[512];
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uint8_t key_data_buf[128];
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struct eapol_key *ek = (struct eapol_key *) frame_buf;
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size_t key_data_len;
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enum crypto_cipher cipher = ie_rsn_cipher_suite_to_cipher(
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sm->handshake->pairwise_cipher);
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const struct crypto_ptk *ptk = (struct crypto_ptk *) sm->handshake->ptk;
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struct ie_rsn_info rsn;
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sm->replay_counter++;
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memset(ek, 0, sizeof(struct eapol_key));
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ek->header.protocol_version = sm->protocol_version;
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ek->header.packet_type = 0x3;
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ek->descriptor_type = EAPOL_DESCRIPTOR_TYPE_80211;
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/* Must be HMAC-SHA1-128 + AES when using CCMP with PSK or 8021X */
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ek->key_descriptor_version = EAPOL_KEY_DESCRIPTOR_VERSION_HMAC_SHA1_AES;
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ek->key_type = true;
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ek->install = true;
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ek->key_ack = true;
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ek->key_mic = true;
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ek->secure = true;
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ek->encrypted_key_data = true;
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ek->key_length = L_CPU_TO_BE16(crypto_cipher_key_len(cipher));
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ek->key_replay_counter = L_CPU_TO_BE64(sm->replay_counter);
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memcpy(ek->key_nonce, sm->handshake->anonce, sizeof(ek->key_nonce));
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/*
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* We don't currently handle group traffic, to support that we'd need
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* to provide the NL80211_ATTR_KEY_SEQ value from NL80211_CMD_GET_KEY
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* here.
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*/
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l_put_be64(1, ek->key_rsc);
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/*
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* Just one RSNE in Key Data as we only set one cipher in ap->ciphers
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* currently.
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*/
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memset(&rsn, 0, sizeof(rsn));
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rsn.akm_suites = IE_RSN_AKM_SUITE_PSK;
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rsn.pairwise_ciphers = sm->handshake->pairwise_cipher;
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rsn.group_cipher = IE_RSN_CIPHER_SUITE_NO_GROUP_TRAFFIC;
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if (!ie_build_rsne(&rsn, key_data_buf))
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return;
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if (!eapol_encrypt_key_data(ptk->kek, key_data_buf,
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2 + key_data_buf[1], ek))
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return;
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key_data_len = L_BE16_TO_CPU(ek->key_data_len);
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ek->header.packet_len = L_CPU_TO_BE16(sizeof(struct eapol_key) +
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key_data_len - 4);
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if (!eapol_calculate_mic(ptk->kck, ek, ek->key_mic_data))
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return;
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l_debug("STA: "MAC" retries=%u", MAC_STR(sm->handshake->spa),
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sm->frame_retry);
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__eapol_tx_packet(ifindex, sm->handshake->spa, ETH_P_PAE,
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(struct eapol_frame *) ek, false);
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}
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static void eapol_ptk_3_of_4_retry(struct l_timeout *timeout,
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void *user_data)
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{
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struct eapol_sm *sm = user_data;
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if (sm->frame_retry >= EAPOL_PAIRWISE_UPDATE_COUNT) {
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handshake_failed(sm, MMPDU_REASON_CODE_4WAY_HANDSHAKE_TIMEOUT);
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return;
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}
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eapol_send_ptk_3_of_4(sm);
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eapol_set_key_timeout(sm, eapol_ptk_3_of_4_retry);
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l_debug("attempt %i", sm->frame_retry);
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}
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/* 802.11-2016 Section 12.7.6.3 */
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static void eapol_handle_ptk_2_of_4(struct eapol_sm *sm,
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const struct eapol_key *ek)
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{
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const uint8_t *rsne;
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enum crypto_cipher cipher;
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size_t ptk_size;
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uint8_t ptk_buf[64];
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struct crypto_ptk *ptk = (struct crypto_ptk *) ptk_buf;
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const uint8_t *aa = sm->handshake->aa;
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l_debug("ifindex=%u", sm->handshake->ifindex);
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if (!eapol_verify_ptk_2_of_4(ek))
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return;
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if (L_BE64_TO_CPU(ek->key_replay_counter) != sm->replay_counter)
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return;
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cipher = ie_rsn_cipher_suite_to_cipher(sm->handshake->pairwise_cipher);
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ptk_size = sizeof(struct crypto_ptk) + crypto_cipher_key_len(cipher);
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if (!crypto_derive_pairwise_ptk(sm->handshake->pmk, sm->handshake->spa,
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aa, sm->handshake->anonce,
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ek->key_nonce, ptk, ptk_size, false))
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return;
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if (!eapol_verify_mic(ptk->kck, ek))
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return;
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/* Bitwise identical RSNE required */
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rsne = eapol_find_rsne(ek->key_data,
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L_BE16_TO_CPU(ek->key_data_len), NULL);
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if (!rsne || rsne[1] != sm->handshake->own_ie[1] ||
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memcmp(rsne + 2, sm->handshake->own_ie + 2, rsne[1])) {
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handshake_failed(sm, MMPDU_REASON_CODE_IE_DIFFERENT);
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return;
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}
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memcpy(sm->handshake->ptk, ptk_buf, ptk_size);
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memcpy(sm->handshake->snonce, ek->key_nonce,
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sizeof(sm->handshake->snonce));
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sm->handshake->have_snonce = true;
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sm->handshake->ptk_complete = true;
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sm->frame_retry = 0;
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eapol_ptk_3_of_4_retry(NULL, sm);
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}
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const uint8_t *eapol_find_rsne(const uint8_t *data, size_t data_len,
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const uint8_t **optional)
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{
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@ -1014,6 +1259,8 @@ static void eapol_handle_ptk_3_of_4(struct eapol_sm *sm,
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uint8_t gtk_key_index;
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uint8_t igtk_key_index;
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l_debug("ifindex=%u", sm->handshake->ifindex);
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if (!eapol_verify_ptk_3_of_4(ek, sm->handshake->wpa_ie)) {
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handshake_failed(sm, MMPDU_REASON_CODE_UNSPECIFIED);
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return;
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@ -1236,6 +1483,29 @@ error_ie_different:
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handshake_failed(sm, MMPDU_REASON_CODE_IE_DIFFERENT);
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}
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/* 802.11-2016 Section 12.7.6.5 */
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static void eapol_handle_ptk_4_of_4(struct eapol_sm *sm,
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const struct eapol_key *ek)
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{
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const struct crypto_ptk *ptk = (struct crypto_ptk *) sm->handshake->ptk;
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l_debug("ifindex=%u", sm->handshake->ifindex);
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if (!eapol_verify_ptk_4_of_4(ek, false))
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return;
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if (L_BE64_TO_CPU(ek->key_replay_counter) != sm->replay_counter)
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return;
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if (!eapol_verify_mic(ptk->kck, ek))
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return;
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l_timeout_remove(sm->timeout);
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sm->timeout = NULL;
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handshake_state_install_ptk(sm->handshake);
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}
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static void eapol_handle_gtk_1_of_2(struct eapol_sm *sm,
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const struct eapol_key *ek,
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const uint8_t *decrypted_key_data,
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@ -1579,6 +1849,54 @@ void eapol_sm_set_require_handshake(struct eapol_sm *sm, bool enabled)
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sm->use_eapol_start = false;
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}
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static void eapol_auth_key_handle(struct eapol_sm *sm,
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const struct eapol_frame *frame)
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{
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size_t frame_len = 4 + L_BE16_TO_CPU(frame->header.packet_len);
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const struct eapol_key *ek = eapol_key_validate((const void *) frame,
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frame_len);
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if (!ek)
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return;
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/* Wrong direction */
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if (ek->key_ack)
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return;
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if (ek->request)
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return; /* Not supported */
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if (!sm->handshake->have_anonce)
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return; /* Not expecting an EAPoL-Key yet */
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if (!sm->handshake->ptk_complete)
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eapol_handle_ptk_2_of_4(sm, ek);
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else
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eapol_handle_ptk_4_of_4(sm, ek);
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}
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static void eapol_rx_auth_packet(uint16_t proto, const uint8_t *from,
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const struct eapol_frame *frame,
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void *user_data)
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{
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struct eapol_sm *sm = user_data;
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if (!sm->protocol_version)
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sm->protocol_version = frame->header.protocol_version;
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switch (frame->header.packet_type) {
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case 3: /* EAPOL-Key */
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eapol_auth_key_handle(sm, frame);
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break;
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default:
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l_error("Authenticator received unknown packet type %i from %s",
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frame->header.packet_type,
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util_address_to_string(from));
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return;
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}
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}
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static void eapol_rx_packet(uint16_t proto, const uint8_t *from,
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const struct eapol_frame *frame,
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void *user_data)
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@ -1700,6 +2018,20 @@ void eapol_register(struct eapol_sm *sm)
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eapol_rx_packet, sm);
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}
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void eapol_register_authenticator(struct eapol_sm *sm)
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{
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l_queue_push_head(state_machines, sm);
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sm->watch_id = eapol_frame_watch_add(sm->handshake->ifindex,
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eapol_rx_auth_packet, sm);
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sm->started = true;
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sm->authenticator = true;
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/* kick off handshake */
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eapol_ptk_1_of_4_retry(NULL, sm);
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}
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bool eapol_start(struct eapol_sm *sm)
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{
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if (sm->handshake->settings_8021x) {
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@ -197,10 +197,12 @@ void eapol_sm_set_protocol_version(struct eapol_sm *sm,
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void eapol_sm_set_use_eapol_start(struct eapol_sm *sm, bool enabled);
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void eapol_sm_set_require_handshake(struct eapol_sm *sm, bool enabled);
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void eapol_sm_set_listen_interval(struct eapol_sm *sm, uint16_t interval);
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void eapol_sm_set_user_data(struct eapol_sm *sm, void *user_data);
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||||
void eapol_sm_set_event_func(struct eapol_sm *sm, eapol_sm_event_func_t func);
|
||||
|
||||
void eapol_register(struct eapol_sm *sm);
|
||||
void eapol_register_authenticator(struct eapol_sm *sm);
|
||||
bool eapol_start(struct eapol_sm *sm);
|
||||
|
||||
uint32_t eapol_frame_watch_add(uint32_t ifindex,
|
||||
|
|
|
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Loading…
Reference in New Issue