/* * * Wireless daemon for Linux * * Copyright (C) 2013-2014 Intel Corporation. All rights reserved. * * This library is free software; you can redistribute it and/or * modify it under the terms of the GNU Lesser General Public * License as published by the Free Software Foundation; either * version 2.1 of the License, or (at your option) any later version. * * This library is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * Lesser General Public License for more details. * * You should have received a copy of the GNU Lesser General Public * License along with this library; if not, write to the Free Software * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA * */ #ifdef HAVE_CONFIG_H #include #endif #include #include #include #include #include #include #include #include #include #include "sha1.h" #include "crypto.h" #include "eapol.h" #include "ie.h" struct l_queue *state_machines; eapol_tx_packet_func_t tx_packet = NULL; eapol_get_nonce_func_t get_nonce = NULL; enum eapol_protocol_version protocol_version = EAPOL_PROTOCOL_VERSION_2004; #define VERIFY_IS_ZERO(field) \ do { \ unsigned int i; \ for (i = 0; i < sizeof(field); i++) \ if ((field)[i] != 0) \ return false; \ } while (false) \ /* * MIC calculation depends on the selected hash function. The has function * is given in the EAPoL Key Descriptor Version field. * * The MIC length is always 16 bytes for currently known Key Descriptor * Versions. * * The input struct eapol_key *frame should have a zero-d MIC field */ bool eapol_calculate_mic(const uint8_t *kck, const struct eapol_key *frame, uint8_t *mic) { size_t frame_len = sizeof(struct eapol_key); frame_len += L_BE16_TO_CPU(frame->key_data_len); switch (frame->key_descriptor_version) { case EAPOL_KEY_DESCRIPTOR_VERSION_HMAC_MD5_ARC4: return hmac_md5(kck, 16, frame, frame_len, mic, 16); case EAPOL_KEY_DESCRIPTOR_VERSION_HMAC_SHA1_AES: return hmac_sha1(kck, 16, frame, frame_len, mic, 16); case EAPOL_KEY_DESCRIPTOR_VERSION_AES_128_CMAC_AES: return cmac_aes(kck, 16, frame, frame_len, mic, 16); default: return false; } } bool eapol_verify_mic(const uint8_t *kck, const struct eapol_key *frame) { size_t frame_len = sizeof(struct eapol_key); uint8_t mic[16]; struct iovec iov[3]; struct l_checksum *checksum = NULL; iov[0].iov_base = (void *) frame; iov[0].iov_len = offsetof(struct eapol_key, key_mic_data); memset(mic, 0, sizeof(mic)); iov[1].iov_base = mic; iov[1].iov_len = sizeof(mic); iov[2].iov_base = ((void *) frame) + offsetof(struct eapol_key, key_data_len); iov[2].iov_len = frame_len - offsetof(struct eapol_key, key_data_len) + L_BE16_TO_CPU(frame->key_data_len); switch (frame->key_descriptor_version) { case EAPOL_KEY_DESCRIPTOR_VERSION_HMAC_MD5_ARC4: checksum = l_checksum_new_hmac(L_CHECKSUM_MD5, kck, 16); break; case EAPOL_KEY_DESCRIPTOR_VERSION_HMAC_SHA1_AES: checksum = l_checksum_new_hmac(L_CHECKSUM_SHA1, kck, 16); break; case EAPOL_KEY_DESCRIPTOR_VERSION_AES_128_CMAC_AES: checksum = l_checksum_new_cmac_aes(kck, 16); break; default: return false; } if (checksum == NULL) return false; l_checksum_updatev(checksum, iov, 3); l_checksum_get_digest(checksum, mic, 16); l_free(checksum); if (!memcmp(frame->key_mic_data, mic, 16)) return true; return false; } uint8_t *eapol_decrypt_key_data(const uint8_t *kek, const struct eapol_key *frame, size_t *decrypted_size) { size_t key_data_len = L_BE16_TO_CPU(frame->key_data_len); const uint8_t *key_data = frame->key_data; size_t expected_len; uint8_t *buf; switch (frame->key_descriptor_version) { case EAPOL_KEY_DESCRIPTOR_VERSION_HMAC_MD5_ARC4: expected_len = key_data_len; break; case EAPOL_KEY_DESCRIPTOR_VERSION_HMAC_SHA1_AES: case EAPOL_KEY_DESCRIPTOR_VERSION_AES_128_CMAC_AES: expected_len = key_data_len - 8; break; default: return NULL; }; buf = l_new(uint8_t, expected_len); switch (frame->key_descriptor_version) { case EAPOL_KEY_DESCRIPTOR_VERSION_HMAC_MD5_ARC4: { uint8_t key[32]; bool ret; memcpy(key, frame->eapol_key_iv, 16); memcpy(key + 16, kek, 16); ret = arc4_skip(key, 32, 256, key_data, key_data_len, buf); memset(key, 0, sizeof(key)); if (!ret) goto error; break; } case EAPOL_KEY_DESCRIPTOR_VERSION_HMAC_SHA1_AES: case EAPOL_KEY_DESCRIPTOR_VERSION_AES_128_CMAC_AES: if (key_data_len < 8 || key_data_len % 8) goto error; if (!aes_unwrap(kek, key_data, key_data_len, buf)) goto error; break; } if (decrypted_size) *decrypted_size = expected_len; return buf; error: l_free(buf); return NULL; } const struct eapol_key *eapol_key_validate(const uint8_t *frame, size_t len) { const struct eapol_key *ek; uint16_t key_data_len; if (len < sizeof(struct eapol_key)) return NULL; ek = (const struct eapol_key *) frame; if (ek->protocol_version != EAPOL_PROTOCOL_VERSION_2001 && ek->protocol_version != EAPOL_PROTOCOL_VERSION_2004) return NULL; if (ek->packet_type != 3) return NULL; switch (ek->descriptor_type) { case EAPOL_DESCRIPTOR_TYPE_RC4: case EAPOL_DESCRIPTOR_TYPE_80211: case EAPOL_DESCRIPTOR_TYPE_WPA: break; default: return NULL; } switch (ek->key_descriptor_version) { case EAPOL_KEY_DESCRIPTOR_VERSION_HMAC_MD5_ARC4: case EAPOL_KEY_DESCRIPTOR_VERSION_HMAC_SHA1_AES: case EAPOL_KEY_DESCRIPTOR_VERSION_AES_128_CMAC_AES: break; default: return NULL; } key_data_len = L_BE16_TO_CPU(ek->key_data_len); if (len < sizeof(struct eapol_key) + key_data_len) return NULL; return ek; } #define VERIFY_PTK_COMMON(ek) \ if (!ek->key_type) \ return false; \ if (ek->smk_message) \ return false; \ if (ek->request) \ return false; \ if (ek->error) \ return false \ bool eapol_verify_ptk_1_of_4(const struct eapol_key *ek) { /* Verify according to 802.11, Section 11.6.6.2 */ VERIFY_PTK_COMMON(ek); if (ek->install) return false; if (!ek->key_ack) return false; if (ek->key_mic) return false; if (ek->secure) return false; if (ek->encrypted_key_data) return false; VERIFY_IS_ZERO(ek->eapol_key_iv); VERIFY_IS_ZERO(ek->key_rsc); VERIFY_IS_ZERO(ek->reserved); VERIFY_IS_ZERO(ek->key_mic_data); return ek; } bool eapol_verify_ptk_2_of_4(const struct eapol_key *ek) { uint16_t key_len; /* Verify according to 802.11, Section 11.6.6.3 */ VERIFY_PTK_COMMON(ek); if (ek->install) return false; if (ek->key_ack) return false; if (!ek->key_mic) return false; if (ek->secure) return false; if (ek->encrypted_key_data) return false; key_len = L_BE16_TO_CPU(ek->key_length); if (key_len != 0) return false; VERIFY_IS_ZERO(ek->eapol_key_iv); VERIFY_IS_ZERO(ek->key_rsc); VERIFY_IS_ZERO(ek->reserved); return true; } bool eapol_verify_ptk_3_of_4(const struct eapol_key *ek) { uint16_t key_len; /* Verify according to 802.11, Section 11.6.6.4 */ VERIFY_PTK_COMMON(ek); if (!ek->key_ack) return false; if (!ek->key_mic) return false; if (!ek->secure) return false; if (!ek->encrypted_key_data) return false; key_len = L_BE16_TO_CPU(ek->key_length); if (key_len != 16) return false; VERIFY_IS_ZERO(ek->reserved); /* 0 (Version 2) or random (Version 1) */ if (ek->key_descriptor_version == EAPOL_KEY_DESCRIPTOR_VERSION_HMAC_MD5_ARC4) VERIFY_IS_ZERO(ek->eapol_key_iv); return true; } bool eapol_verify_ptk_4_of_4(const struct eapol_key *ek) { uint16_t key_len; /* Verify according to 802.11, Section 11.6.6.5 */ VERIFY_PTK_COMMON(ek); if (ek->key_ack) return false; if (!ek->key_mic) return false; if (!ek->secure) return false; if (ek->encrypted_key_data) return false; key_len = L_BE16_TO_CPU(ek->key_length); if (key_len != 0) return false; VERIFY_IS_ZERO(ek->key_nonce); VERIFY_IS_ZERO(ek->eapol_key_iv); VERIFY_IS_ZERO(ek->key_rsc); VERIFY_IS_ZERO(ek->reserved); return true; } static struct eapol_key *eapol_create_common( enum eapol_protocol_version protocol, enum eapol_key_descriptor_version version, bool secure, uint64_t key_replay_counter, const uint8_t snonce[], size_t extra_len, const uint8_t *extra_data) { size_t to_alloc = sizeof(struct eapol_key); struct eapol_key *out_frame = l_malloc(to_alloc + extra_len); memset(out_frame, 0, to_alloc + extra_len); out_frame->protocol_version = protocol; out_frame->packet_type = 0x3; out_frame->packet_len = L_CPU_TO_BE16(to_alloc + extra_len - 4); out_frame->descriptor_type = EAPOL_DESCRIPTOR_TYPE_80211; out_frame->key_descriptor_version = version; out_frame->key_type = true; out_frame->install = false; out_frame->key_ack = false; out_frame->key_mic = true; out_frame->secure = secure; out_frame->error = false; out_frame->request = false; out_frame->encrypted_key_data = false; out_frame->smk_message = false; out_frame->key_length = 0; out_frame->key_replay_counter = L_CPU_TO_BE64(key_replay_counter); memcpy(out_frame->key_nonce, snonce, sizeof(out_frame->key_nonce)); out_frame->key_data_len = L_CPU_TO_BE16(extra_len); memcpy(out_frame->key_data, extra_data, extra_len); return out_frame; } struct eapol_key *eapol_create_ptk_2_of_4( enum eapol_protocol_version protocol, enum eapol_key_descriptor_version version, uint64_t key_replay_counter, const uint8_t snonce[], size_t extra_len, const uint8_t *extra_data) { return eapol_create_common(protocol, version, false, key_replay_counter, snonce, extra_len, extra_data); } struct eapol_key *eapol_create_ptk_4_of_4( enum eapol_protocol_version protocol, enum eapol_key_descriptor_version version, uint64_t key_replay_counter) { uint8_t snonce[32]; memset(snonce, 0, sizeof(snonce)); return eapol_create_common(protocol, version, true, key_replay_counter, snonce, 0, NULL); } struct eapol_sm { uint32_t ifindex; uint8_t sta_addr[6]; uint8_t aa_addr[6]; uint8_t *ap_rsn; uint8_t *own_rsn; uint8_t pmk[32]; uint64_t replay_counter; uint8_t snonce[32]; uint8_t anonce[32]; uint8_t ptk[64]; bool have_snonce:1; bool have_replay:1; }; static void eapol_sm_destroy(void *value) { struct eapol_sm *sm = value; l_free(sm->ap_rsn); l_free(sm->own_rsn); l_free(sm); } struct eapol_sm *eapol_sm_new() { struct eapol_sm *sm; sm = l_new(struct eapol_sm, 1); return sm; } void eapol_sm_free(struct eapol_sm *sm) { eapol_sm_destroy(sm); } void eapol_sm_set_sta_address(struct eapol_sm *sm, const uint8_t *sta_addr) { memcpy(sm->sta_addr, sta_addr, sizeof(sm->sta_addr)); } void eapol_sm_set_aa_address(struct eapol_sm *sm, const uint8_t *aa_addr) { memcpy(sm->aa_addr, aa_addr, sizeof(sm->aa_addr)); } void eapol_sm_set_pmk(struct eapol_sm *sm, const uint8_t *pmk) { memcpy(sm->pmk, pmk, sizeof(sm->pmk)); } void eapol_sm_set_ap_rsn(struct eapol_sm *sm, const uint8_t *rsn_ie, size_t len) { if (rsn_ie[1] + 2u != len) return; l_free(sm->ap_rsn); sm->ap_rsn = l_memdup(rsn_ie, len); } void eapol_sm_set_own_rsn(struct eapol_sm *sm, const uint8_t *rsn_ie, size_t len) { if (rsn_ie[1] + 2u != len) return; l_free(sm->own_rsn); sm->own_rsn = l_memdup(rsn_ie, len); } void eapol_start(uint32_t ifindex, struct eapol_sm *sm) { sm->ifindex = ifindex; l_queue_push_head(state_machines, sm); } static void eapol_handle_ptk_1_of_4(uint32_t ifindex, struct eapol_sm *sm, const struct eapol_key *ek) { struct crypto_ptk *ptk = (struct crypto_ptk *) sm->ptk; struct eapol_key *step2; uint8_t mic[16]; if (!eapol_verify_ptk_1_of_4(ek)) return; if (!sm->have_snonce) { if (!get_nonce(sm->snonce)) return; sm->have_snonce = true; } memcpy(sm->anonce, ek->key_nonce, sizeof(ek->key_nonce)); crypto_derive_pairwise_ptk(sm->pmk, sm->sta_addr, sm->aa_addr, sm->anonce, sm->snonce, ptk, sizeof(sm->ptk)); step2 = eapol_create_ptk_2_of_4(protocol_version, ek->key_descriptor_version, sm->replay_counter, sm->snonce, sm->own_rsn[1] + 2, sm->own_rsn); if (!eapol_calculate_mic(ptk->kck, step2, mic)) goto fail; memcpy(step2->key_mic_data, mic, sizeof(mic)); tx_packet(ifindex, sm->aa_addr, sm->sta_addr, step2); fail: l_free(step2); } static const uint8_t *eapol_find_gtk_kde(const uint8_t *data, size_t data_len, size_t *out_gtk_len) { static const unsigned char gtk_oui[] = { 0x00, 0x0f, 0xac, 0x01 }; struct ie_tlv_iter iter; const uint8_t *gtk; unsigned int len; ie_tlv_iter_init(&iter, data, data_len); while (ie_tlv_iter_next(&iter)) { if (ie_tlv_iter_get_tag(&iter) != IE_TYPE_VENDOR_SPECIFIC) continue; len = ie_tlv_iter_get_length(&iter); if (len < 4) /* Take care of padding */ return NULL; /* Check OUI */ gtk = ie_tlv_iter_get_data(&iter); if (memcmp(gtk, gtk_oui, 4)) continue; if (out_gtk_len) *out_gtk_len = len - 4; return gtk + 4; } return NULL; } static const uint8_t *eapol_find_rsne(const uint8_t *data, size_t data_len) { struct ie_tlv_iter iter; ie_tlv_iter_init(&iter, data, data_len); while (ie_tlv_iter_next(&iter)) { if (ie_tlv_iter_get_tag(&iter) != IE_TYPE_RSN) continue; return ie_tlv_iter_get_data(&iter) - 2; } return NULL; } /* * This function performs a match of the RSN IE obtained from the scan * results vs the RSN IE obtained as part of the 4-way handshake. If they * don't match, the EAPoL packet must be silently discarded. */ static bool eapol_ap_rsne_matches(const uint8_t *eapol_rsne, const uint8_t *scan_rsne) { struct ie_rsn_info eapol_info; struct ie_rsn_info scan_info; /* * First check that the sizes match, if they do, run a bitwise * comparison. */ if (eapol_rsne[1] == scan_rsne[1] && !memcmp(eapol_rsne + 2, scan_rsne + 2, eapol_rsne[1])) return true; /* * Otherwise we have to parse the RSN IEs and compare the individual * fields */ if (ie_parse_rsne_from_data(eapol_rsne, eapol_rsne[1] + 2, &eapol_info) < 0) return false; if (ie_parse_rsne_from_data(scan_rsne, scan_rsne[1] + 2, &scan_info) < 0) return false; if (eapol_info.group_cipher != scan_info.group_cipher) return false; if (eapol_info.pairwise_ciphers != scan_info.pairwise_ciphers) return false; if (eapol_info.akm_suites != scan_info.akm_suites) return false; if (eapol_info.preauthentication != scan_info.preauthentication) return false; if (eapol_info.no_pairwise != scan_info.no_pairwise) return false; if (eapol_info.ptksa_replay_counter != scan_info.ptksa_replay_counter) return false; if (eapol_info.gtksa_replay_counter != scan_info.gtksa_replay_counter) return false; if (eapol_info.mfpr != scan_info.mfpr) return false; if (eapol_info.mfpc != scan_info.mfpc) return false; if (eapol_info.peerkey_enabled != scan_info.peerkey_enabled) return false; if (eapol_info.spp_a_msdu_capable != scan_info.spp_a_msdu_capable) return false; if (eapol_info.spp_a_msdu_required != scan_info.spp_a_msdu_required) return false; if (eapol_info.pbac != scan_info.pbac) return false; if (eapol_info.extended_key_id != scan_info.extended_key_id) return false; /* We don't check the PMKIDs since these might actually be different */ if (eapol_info.group_management_cipher != scan_info.group_management_cipher) return false; return true; } static void eapol_handle_ptk_3_of_4(uint32_t ifindex, struct eapol_sm *sm, const struct eapol_key *ek, const uint8_t *decrypted_key_data, size_t decrypted_key_data_size) { struct crypto_ptk *ptk = (struct crypto_ptk *) sm->ptk; struct eapol_key *step4; uint8_t mic[16]; const uint8_t *gtk; size_t gtk_len; const uint8_t *rsne; if (!eapol_verify_ptk_3_of_4(ek)) return; /* * 11.6.6.4: "On reception of Message 3, the Supplicant silently * discards the message if ... or if the ANonce value in Message 3 * differs from the ANonce value in Message 1" */ if (memcmp(sm->anonce, ek->key_nonce, sizeof(ek->key_nonce))) return; /* * 11.6.6.4: "Verifies the RSNE. If it is part of a Fast BSS Transition * Initial Mobility Domain Association, see 12.4.2. Otherwise, if it is * not identical to that the STA received in the Beacon or Probe * Response frame, the STA shall disassociate. */ rsne = eapol_find_rsne(decrypted_key_data, decrypted_key_data_size); if (!rsne) return; if (!eapol_ap_rsne_matches(rsne, sm->ap_rsn)) return; /* * TODO: Parse second RSNE * 11.6.6.4: "If a second RSNE is provided in the message, the * Supplicant uses the pairwise cipher suite specified in the second * RSNE or deauthenticates." */ /* * TODO: If group_cipher was negotiated, find the GTK and install it */ gtk = eapol_find_gtk_kde(decrypted_key_data, decrypted_key_data_size, >k_len); if (!gtk) return; step4 = eapol_create_ptk_4_of_4(protocol_version, ek->key_descriptor_version, sm->replay_counter); if (!eapol_calculate_mic(ptk->kck, step4, mic)) goto fail; memcpy(step4->key_mic_data, mic, sizeof(mic)); tx_packet(ifindex, sm->aa_addr, sm->sta_addr, step4); fail: l_free(step4); } static struct eapol_sm *eapol_find_sm(uint32_t ifindex, const uint8_t *sta_addr, const uint8_t *aa_addr) { const struct l_queue_entry *entry; struct eapol_sm *sm; for (entry = l_queue_get_entries(state_machines); entry; entry = entry->next) { sm = entry->data; if (sm->ifindex != ifindex) continue; if (memcmp(sm->sta_addr, sta_addr, 6)) continue; if (memcmp(sm->aa_addr, aa_addr, 6)) continue; return sm; } return NULL; } void __eapol_rx_packet(uint32_t ifindex, const uint8_t *sta_addr, const uint8_t *aa_addr, const uint8_t *frame, size_t len) { const struct eapol_key *ek; struct eapol_sm *sm; struct crypto_ptk *ptk; uint8_t *decrypted_key_data = NULL; size_t decrypted_key_data_len; uint64_t replay_counter; ek = eapol_key_validate(frame, len); if (!ek) return; sm = eapol_find_sm(ifindex, sta_addr, aa_addr); /* Wrong direction */ if (!ek->key_ack) return; replay_counter = L_BE64_TO_CPU(ek->key_replay_counter); /* * 11.6.6.2: "If the Key Replay Counter field value is less than or * equal to the current local value, the Supplicant discards the * message. * * 11.6.6.4: "On reception of Message 3, the Supplicant silently * discards the message if the Key Replay Counter field value has * already been used... */ if (sm->have_replay && sm->replay_counter >= replay_counter) return; sm->replay_counter = replay_counter; sm->have_replay = true; ptk = (struct crypto_ptk *) sm->ptk; if (ek->key_mic) { /* Haven't received step 1 yet, so no ptk */ if (!sm->have_snonce) return; if (!eapol_verify_mic(ptk->kck, ek)) return; } if (ek->encrypted_key_data) { /* Haven't received step 1 yet, so no ptk */ if (!sm->have_snonce) return; decrypted_key_data = eapol_decrypt_key_data(ptk->kek, ek, &decrypted_key_data_len); if (!decrypted_key_data) return; } /* TODO: Handle Group Key Handshake */ if (ek->key_type == 0) goto done; /* If no MIC, then assume packet 1, otherwise packet 3 */ if (!ek->key_mic) eapol_handle_ptk_1_of_4(ifindex, sm, ek); else eapol_handle_ptk_3_of_4(ifindex, sm, ek, decrypted_key_data, decrypted_key_data_len); done: l_free(decrypted_key_data); } void __eapol_set_tx_packet_func(eapol_tx_packet_func_t func) { tx_packet = func; } void __eapol_set_get_nonce_func(eapol_get_nonce_func_t func) { get_nonce = func; } void __eapol_set_protocol_version(enum eapol_protocol_version version) { protocol_version = version; } struct l_io *eapol_open_pae(uint32_t index) { struct l_io *io; struct sockaddr_ll sll; int fd; fd = socket(PF_PACKET, SOCK_RAW | SOCK_CLOEXEC, 0); if (fd < 0) { l_error("Failed to create PAE socket %s (%d)", strerror(errno), errno); return NULL; } memset(&sll, 0, sizeof(sll)); sll.sll_family = AF_PACKET; sll.sll_protocol = htons(ETH_P_PAE); sll.sll_ifindex = index; if (bind(fd, (struct sockaddr *) &sll, sizeof(sll)) < 0) { l_error("Failed to bind PAE socket %s (%d)", strerror(errno), errno); close(fd); return NULL; } io = l_io_new(fd); if (!io) { l_error("Failed to create IO handling for PAE socket "); close(fd); return NULL; } l_io_set_close_on_destroy(io, true); return io; } bool eapol_init() { state_machines = l_queue_new(); protocol_version = EAPOL_PROTOCOL_VERSION_2004; return true; } bool eapol_exit() { l_queue_destroy(state_machines, eapol_sm_destroy); get_nonce = NULL; tx_packet = NULL; return true; }