diff options
Diffstat (limited to 'src/libcharon/plugins/eap_mschapv2/eap_mschapv2.c')
| -rw-r--r-- | src/libcharon/plugins/eap_mschapv2/eap_mschapv2.c | 1250 |
1 files changed, 1250 insertions, 0 deletions
diff --git a/src/libcharon/plugins/eap_mschapv2/eap_mschapv2.c b/src/libcharon/plugins/eap_mschapv2/eap_mschapv2.c new file mode 100644 index 000000000..c1ccf72eb --- /dev/null +++ b/src/libcharon/plugins/eap_mschapv2/eap_mschapv2.c @@ -0,0 +1,1250 @@ +/* + * Copyright (C) 2009 Tobias Brunner + * Copyright (C) 2010 Martin Willi + * Hochschule fuer Technik Rapperswil + * + * This program is free software; you can redistribute it and/or modify it + * under the terms of the GNU General Public License as published by the + * Free Software Foundation; either version 2 of the License, or (at your + * option) any later version. See <http://www.fsf.org/copyleft/gpl.txt>. + * + * This program 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 General Public License + * for more details. + */ + +#include "eap_mschapv2.h" + +#include <ctype.h> +#include <unistd.h> + +#include <daemon.h> +#include <library.h> +#include <utils/enumerator.h> +#include <crypto/crypters/crypter.h> +#include <crypto/hashers/hasher.h> + +typedef struct private_eap_mschapv2_t private_eap_mschapv2_t; + +/** + * Private data of an eap_mschapv2_t object. + */ +struct private_eap_mschapv2_t +{ + /** + * Public authenticator_t interface. + */ + eap_mschapv2_t public; + + /** + * ID of the server + */ + identification_t *server; + + /** + * ID of the peer + */ + identification_t *peer; + + /** + * challenge sent by the server + */ + chunk_t challenge; + + /** + * generated NT-Response + */ + chunk_t nt_response; + + /** + * generated Authenticator Response + */ + chunk_t auth_response; + + /** + * generated MSK + */ + chunk_t msk; + + /** + * EAP message identifier + */ + u_int8_t identifier; + + /** + * MS-CHAPv2-ID (session ID, increases with each retry) + */ + u_int8_t mschapv2id; + + /** + * Number of retries + */ + int retries; +}; + +/** + * OpCodes + */ +enum mschapv2_opcode_t +{ + MSCHAPV2_CHALLENGE = 1, + MSCHAPV2_RESPONSE = 2, + MSCHAPV2_SUCCESS = 3, + MSCHAPV2_FAILURE = 4, + MSCHAPV2_CHANGE_PASSWORD = 7, +}; + +/** + * Names for OpCodes + */ +ENUM_BEGIN(mschapv2_opcode_names, MSCHAPV2_CHALLENGE, MSCHAPV2_FAILURE, + "CHALLENGE", + "RESPONSE", + "SUCCESS", + "FAILURE"); +ENUM_NEXT(mschapv2_opcode_names, MSCHAPV2_CHANGE_PASSWORD, MSCHAPV2_CHANGE_PASSWORD, MSCHAPV2_FAILURE, + "CHANGE_PASSWORD"); +ENUM_END(mschapv2_opcode_names, MSCHAPV2_CHANGE_PASSWORD); + +/** + * Error codes + */ +enum mschapv2_error_t +{ + ERROR_RESTRICTED_LOGON_HOURS = 646, + ERROR_ACCT_DISABLED = 647, + ERROR_PASSWD_EXPIRED = 648, + ERROR_NO_DIALIN_PERMISSION = 649, + ERROR_AUTHENTICATION_FAILURE = 691, + ERROR_CHANGING_PASSWORD = 709, +}; + +/** + * Names for error codes + */ +ENUM_BEGIN(mschapv2_error_names, ERROR_RESTRICTED_LOGON_HOURS, ERROR_NO_DIALIN_PERMISSION, + "ERROR_RESTRICTED_LOGON_HOURS", + "ERROR_ACCT_DISABLED", + "ERROR_PASSWD_EXPIRED", + "ERROR_NO_DIALIN_PERMISSION"); +ENUM_NEXT(mschapv2_error_names, ERROR_AUTHENTICATION_FAILURE, ERROR_AUTHENTICATION_FAILURE, ERROR_NO_DIALIN_PERMISSION, + "ERROR_AUTHENTICATION_FAILURE"); +ENUM_NEXT(mschapv2_error_names, ERROR_CHANGING_PASSWORD, ERROR_CHANGING_PASSWORD, ERROR_AUTHENTICATION_FAILURE, + "ERROR_CHANGING_PASSWORD"); +ENUM_END(mschapv2_error_names, ERROR_CHANGING_PASSWORD); + +/* Length of the challenge */ +#define CHALLENGE_LEN 16 +/* Length of the response (see eap_mschapv2_response_t) */ +#define RESPONSE_LEN 49 +/* Length of the authenticator response string ("S=<...>") */ +#define AUTH_RESPONSE_LEN 42 +/* Name we send as authenticator */ +#define MSCHAPV2_HOST_NAME "strongSwan" +/* Message sent on success */ +#define SUCCESS_MESSAGE " M=Welcome2strongSwan" +/* Message sent on failure */ +#define FAILURE_MESSAGE "E=691 R=1 C=" +/* Length of the complete failure message */ +#define FAILURE_MESSAGE_LEN (sizeof(FAILURE_MESSAGE) + CHALLENGE_LEN * 2) + +/* Number of seconds to delay retries */ +#define RETRY_DELAY 2 +/* Maximum number of retries */ +#define MAX_RETRIES 2 + +typedef struct eap_mschapv2_header_t eap_mschapv2_header_t; +typedef struct eap_mschapv2_challenge_t eap_mschapv2_challenge_t; +typedef struct eap_mschapv2_response_t eap_mschapv2_response_t; + +/** + * packed EAP-MS-CHAPv2 header struct + */ +struct eap_mschapv2_header_t +{ + /** EAP code (REQUEST/RESPONSE) */ + u_int8_t code; + /** unique message identifier */ + u_int8_t identifier; + /** length of whole message */ + u_int16_t length; + /** EAP type */ + u_int8_t type; + /** MS-CHAPv2 OpCode */ + u_int8_t opcode; + /** MS-CHAPv2-ID (equals identifier) */ + u_int8_t ms_chapv2_id; + /** MS-Length (defined as length - 5) */ + u_int16_t ms_length; + /** packet data (determined by OpCode) */ + u_int8_t data[]; +}__attribute__((__packed__)); + +/** + * packed data for a MS-CHAPv2 Challenge packet + */ +struct eap_mschapv2_challenge_t +{ + /** Value-Size */ + u_int8_t value_size; + /** Challenge */ + u_int8_t challenge[CHALLENGE_LEN]; + /** Name */ + u_int8_t name[]; +}__attribute__((__packed__)); + +/** + * packed data for a MS-CHAPv2 Response packet + */ +struct eap_mschapv2_response_t +{ + /** Value-Size */ + u_int8_t value_size; + /** Response */ + struct + { + /* Peer-Challenge*/ + u_int8_t peer_challenge[CHALLENGE_LEN]; + /* Reserved (=zero) */ + u_int8_t peer_reserved[8]; + /* NT-Response */ + u_int8_t nt_response[24]; + /* Flags (=zero) */ + u_int8_t flags; + } response; + /** Name */ + u_int8_t name[]; +}__attribute__((__packed__)); + +/** + * Length of the MS-CHAPv2 header + */ +#define HEADER_LEN (sizeof(eap_mschapv2_header_t)) + +/** + * Length of the header for MS-CHAPv2 success/failure packets (does not include + * MS-CHAPv2-ID and MS-Length, i.e. 3 octets) + */ +#define SHORT_HEADER_LEN (HEADER_LEN - 3) + +/** + * The minimum length of an MS-CHAPv2 Challenge packet (the name MUST be + * at least one octet) + */ +#define CHALLENGE_PAYLOAD_LEN (HEADER_LEN + sizeof(eap_mschapv2_challenge_t)) + +/** + * The minimum length of an MS-CHAPv2 Response packet + */ +#define RESPONSE_PAYLOAD_LEN (HEADER_LEN + sizeof(eap_mschapv2_response_t)) + + +/** + * Expand a 56-bit key to a 64-bit DES key by adding parity bits (odd parity) + */ +static chunk_t ExpandDESKey(chunk_t key) +{ + static const u_char bitmask[] = { 0xfe, 0xfc, 0xf8, 0xf0, 0xe0, 0xc0, 0x80 }; + int i; + u_char carry = 0; + chunk_t expanded; + + /* expand the 7 octets to 8 octets */ + expanded = chunk_alloc(8); + for (i = 0; i < 7; i++) + { + expanded.ptr[i] = ((key.ptr[i] & bitmask[i]) >> i) | (carry << (8 - i)); + carry = key.ptr[i] & ~bitmask[i]; + } + expanded.ptr[7] = carry << 1; + + /* add parity bits to each octet */ + for (i = 0; i < 8; i++) + { + u_char val = expanded.ptr[i]; + val = (val ^ (val >> 4)) & 0x0f; + expanded.ptr[i] |= (0x9669 >> val) & 1; + } + return expanded; +} + +/** + * Calculate the NT password hash (i.e. hash the (unicode) password with MD4) + */ +static status_t NtPasswordHash(chunk_t password, chunk_t *password_hash) +{ + hasher_t *hasher; + hasher = lib->crypto->create_hasher(lib->crypto, HASH_MD4); + if (hasher == NULL) + { + DBG1(DBG_IKE, "EAP-MS-CHAPv2 failed, no MD4 hasher available"); + return FAILED; + } + hasher->allocate_hash(hasher, password, password_hash); + hasher->destroy(hasher); + return SUCCESS; +} + +/** + * Calculate the challenge hash (i.e. hash [peer_challenge | server_challenge | + * username (without domain part)] with SHA1) + */ +static status_t ChallengeHash(chunk_t peer_challenge, chunk_t server_challenge, + chunk_t username, chunk_t *challenge_hash) +{ + chunk_t concat; + hasher_t *hasher; + hasher = lib->crypto->create_hasher(lib->crypto, HASH_SHA1); + if (hasher == NULL) + { + DBG1(DBG_IKE, "EAP-MS-CHAPv2 failed, SHA1 not supported"); + return FAILED; + } + concat = chunk_cata("ccc", peer_challenge, server_challenge, username); + hasher->allocate_hash(hasher, concat, challenge_hash); + hasher->destroy(hasher); + /* we need only the first 8 octets */ + challenge_hash->len = 8; + return SUCCESS; +} + +/** + * Calculate the challenge response (i.e. expand password_hash to three DES keys + * and then encrypt the 8-octet challenge_hash with these keys and concatenate + * the results). + */ +static status_t ChallengeResponse(chunk_t challenge_hash, chunk_t password_hash, + chunk_t *response) +{ + int i; + crypter_t *crypter; + chunk_t keys[3], z_password_hash; + crypter = lib->crypto->create_crypter(lib->crypto, ENCR_DES_ECB, 8); + if (crypter == NULL) + { + DBG1(DBG_IKE, "EAP-MS-CHAPv2 failed, DES-ECB not supported"); + return FAILED; + } + /* prepare keys: first pad password_hash to 21 octets, these get then split + * into 7-octet chunks, which then get expanded into 8-octet DES keys */ + z_password_hash = chunk_alloca(21); + memset(z_password_hash.ptr, 0, z_password_hash.len); + memcpy(z_password_hash.ptr, password_hash.ptr, password_hash.len); + chunk_split(z_password_hash, "mmm", 7, &keys[0], 7, &keys[1], 7, &keys[2]); + + *response = chunk_alloc(24); + for (i = 0; i < 3; i++) + { + chunk_t expanded, encrypted; + expanded = ExpandDESKey(keys[i]); + crypter->set_key(crypter, expanded); + crypter->encrypt(crypter, challenge_hash, chunk_empty, &encrypted); + memcpy(&response->ptr[i * 8], encrypted.ptr, encrypted.len); + chunk_clear(&encrypted); + chunk_clear(&expanded); + } + crypter->destroy(crypter); + return SUCCESS; +} + +/** + * Computes the authenticator response + */ +static status_t AuthenticatorResponse(chunk_t password_hash_hash, + chunk_t challenge_hash, chunk_t nt_response, chunk_t *response) +{ + chunk_t magic1 = chunk_from_chars( + 0x4D, 0x61, 0x67, 0x69, 0x63, 0x20, 0x73, 0x65, 0x72, 0x76, + 0x65, 0x72, 0x20, 0x74, 0x6F, 0x20, 0x63, 0x6C, 0x69, 0x65, + 0x6E, 0x74, 0x20, 0x73, 0x69, 0x67, 0x6E, 0x69, 0x6E, 0x67, + 0x20, 0x63, 0x6F, 0x6E, 0x73, 0x74, 0x61, 0x6E, 0x74); + chunk_t magic2 = chunk_from_chars( + 0x50, 0x61, 0x64, 0x20, 0x74, 0x6F, 0x20, 0x6D, 0x61, 0x6B, + 0x65, 0x20, 0x69, 0x74, 0x20, 0x64, 0x6F, 0x20, 0x6D, 0x6F, + 0x72, 0x65, 0x20, 0x74, 0x68, 0x61, 0x6E, 0x20, 0x6F, 0x6E, + 0x65, 0x20, 0x69, 0x74, 0x65, 0x72, 0x61, 0x74, 0x69, 0x6F, + 0x6E); + chunk_t digest = chunk_empty, concat; + hasher_t *hasher; + + hasher = lib->crypto->create_hasher(lib->crypto, HASH_SHA1); + if (hasher == NULL) + { + DBG1(DBG_IKE, "EAP-MS-CHAPv2 failed, SHA1 not supported"); + return FAILED; + } + + concat = chunk_cata("ccc", password_hash_hash, nt_response, magic1); + hasher->allocate_hash(hasher, concat, &digest); + concat = chunk_cata("ccc", digest, challenge_hash, magic2); + hasher->allocate_hash(hasher, concat, response); + + hasher->destroy(hasher); + chunk_free(&digest); + return SUCCESS; +} + +/** + * Generate the master session key according to RFC3079 + */ +static status_t GenerateMSK(chunk_t password_hash_hash, + chunk_t nt_response, chunk_t *msk) +{ + chunk_t magic1 = chunk_from_chars( + 0x54, 0x68, 0x69, 0x73, 0x20, 0x69, 0x73, 0x20, 0x74, + 0x68, 0x65, 0x20, 0x4d, 0x50, 0x50, 0x45, 0x20, 0x4d, + 0x61, 0x73, 0x74, 0x65, 0x72, 0x20, 0x4b, 0x65, 0x79); + chunk_t magic2 = chunk_from_chars( + 0x4f, 0x6e, 0x20, 0x74, 0x68, 0x65, 0x20, 0x63, 0x6c, 0x69, + 0x65, 0x6e, 0x74, 0x20, 0x73, 0x69, 0x64, 0x65, 0x2c, 0x20, + 0x74, 0x68, 0x69, 0x73, 0x20, 0x69, 0x73, 0x20, 0x74, 0x68, + 0x65, 0x20, 0x73, 0x65, 0x6e, 0x64, 0x20, 0x6b, 0x65, 0x79, + 0x3b, 0x20, 0x6f, 0x6e, 0x20, 0x74, 0x68, 0x65, 0x20, 0x73, + 0x65, 0x72, 0x76, 0x65, 0x72, 0x20, 0x73, 0x69, 0x64, 0x65, + 0x2c, 0x20, 0x69, 0x74, 0x20, 0x69, 0x73, 0x20, 0x74, 0x68, + 0x65, 0x20, 0x72, 0x65, 0x63, 0x65, 0x69, 0x76, 0x65, 0x20, + 0x6b, 0x65, 0x79, 0x2e); + chunk_t magic3 = chunk_from_chars( + 0x4f, 0x6e, 0x20, 0x74, 0x68, 0x65, 0x20, 0x63, 0x6c, 0x69, + 0x65, 0x6e, 0x74, 0x20, 0x73, 0x69, 0x64, 0x65, 0x2c, 0x20, + 0x74, 0x68, 0x69, 0x73, 0x20, 0x69, 0x73, 0x20, 0x74, 0x68, + 0x65, 0x20, 0x72, 0x65, 0x63, 0x65, 0x69, 0x76, 0x65, 0x20, + 0x6b, 0x65, 0x79, 0x3b, 0x20, 0x6f, 0x6e, 0x20, 0x74, 0x68, + 0x65, 0x20, 0x73, 0x65, 0x72, 0x76, 0x65, 0x72, 0x20, 0x73, + 0x69, 0x64, 0x65, 0x2c, 0x20, 0x69, 0x74, 0x20, 0x69, 0x73, + 0x20, 0x74, 0x68, 0x65, 0x20, 0x73, 0x65, 0x6e, 0x64, 0x20, + 0x6b, 0x65, 0x79, 0x2e); + chunk_t shapad1 = chunk_from_chars( + 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, + 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, + 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, + 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00); + chunk_t shapad2 = chunk_from_chars( + 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, + 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, + 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, + 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2); + chunk_t keypad = chunk_from_chars( + 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, + 0x00, 0x00, 0x00, 0x00, 0x00, 0x00); + chunk_t concat, master_key, master_receive_key, master_send_key; + hasher_t *hasher; + + hasher = lib->crypto->create_hasher(lib->crypto, HASH_SHA1); + if (hasher == NULL) + { + DBG1(DBG_IKE, "EAP-MS-CHAPv2 failed, SHA1 not supported"); + return FAILED; + } + + concat = chunk_cata("ccc", password_hash_hash, nt_response, magic1); + hasher->allocate_hash(hasher, concat, &master_key); + master_key.len = 16; + + concat = chunk_cata("cccc", master_key, shapad1, magic2, shapad2); + hasher->allocate_hash(hasher, concat, &master_receive_key); + master_receive_key.len = 16; + + concat = chunk_cata("cccc", master_key, shapad1, magic3, shapad2); + hasher->allocate_hash(hasher, concat, &master_send_key); + master_send_key.len = 16; + + *msk = chunk_cat("cccc", master_receive_key, master_send_key, keypad, keypad); + + hasher->destroy(hasher); + chunk_free(&master_key); + chunk_free(&master_receive_key); + chunk_free(&master_send_key); + return SUCCESS; +} + +static status_t GenerateStuff(private_eap_mschapv2_t *this, + chunk_t server_challenge, chunk_t peer_challenge, + chunk_t username, chunk_t nt_hash) +{ + status_t status = FAILED; + chunk_t nt_hash_hash = chunk_empty, challenge_hash = chunk_empty; + + if (NtPasswordHash(nt_hash, &nt_hash_hash) != SUCCESS) + { + goto error; + } + if (ChallengeHash(peer_challenge, server_challenge, username, + &challenge_hash) != SUCCESS) + { + goto error; + } + if (ChallengeResponse(challenge_hash, nt_hash, + &this->nt_response) != SUCCESS) + { + goto error; + } + if (AuthenticatorResponse(nt_hash_hash, challenge_hash, + this->nt_response, &this->auth_response) != SUCCESS) + { + goto error; + } + if (GenerateMSK(nt_hash_hash, this->nt_response, &this->msk) != SUCCESS) + { + goto error; + } + + status = SUCCESS; + +error: + chunk_free(&nt_hash_hash); + chunk_free(&challenge_hash); + return status; +} + +/** + * Converts an ASCII string into a UTF-16 (little-endian) string + */ +static chunk_t ascii_to_unicode(chunk_t ascii) +{ + int i; + chunk_t unicode = chunk_alloc(ascii.len * 2); + for (i = 0; i < ascii.len; i++) + { + unicode.ptr[i * 2] = ascii.ptr[i]; + unicode.ptr[i * 2 + 1] = 0; + } + return unicode; +} + +/** + * sanitize a string for printing + */ +static char* sanitize(char *str) +{ + char *pos = str; + + while (pos && *pos) + { + if (!isprint(*pos)) + { + *pos = '?'; + } + pos++; + } + return str; +} + +/** + * Returns a chunk of just the username part of the given user identity. + * Note: the chunk points to internal data of the identification. + */ +static chunk_t extract_username(identification_t* identification) +{ + char *has_domain; + chunk_t id; + id = identification->get_encoding(identification); + has_domain = (char*)memchr(id.ptr, '\\', id.len); + if (has_domain) + { + int len; + has_domain++; /* skip the backslash */ + len = id.len - ((u_char*)has_domain - id.ptr); + return len > 0 ? chunk_create(has_domain, len) : chunk_empty; + } + return id; +} + +/** + * Set the ms_length field using aligned write + */ +static void set_ms_length(eap_mschapv2_header_t *eap, u_int16_t len) +{ + len = htons(len - 5); + memcpy(&eap->ms_length, &len, sizeof(u_int16_t)); +} + +/** + * Implementation of eap_method_t.initiate for the peer + */ +static status_t initiate_peer(private_eap_mschapv2_t *this, eap_payload_t **out) +{ + /* peer never initiates */ + return FAILED; +} + +/** + * Implementation of eap_method_t.initiate for the server + */ +static status_t initiate_server(private_eap_mschapv2_t *this, eap_payload_t **out) +{ + rng_t *rng; + eap_mschapv2_header_t *eap; + eap_mschapv2_challenge_t *cha; + const char *name = MSCHAPV2_HOST_NAME; + u_int16_t len = CHALLENGE_PAYLOAD_LEN + sizeof(MSCHAPV2_HOST_NAME) - 1; + + rng = lib->crypto->create_rng(lib->crypto, RNG_WEAK); + if (!rng) + { + DBG1(DBG_IKE, "EAP-MS-CHAPv2 failed, no RNG"); + return FAILED; + } + rng->allocate_bytes(rng, CHALLENGE_LEN, &this->challenge); + rng->destroy(rng); + + eap = alloca(len); + eap->code = EAP_REQUEST; + eap->identifier = this->identifier; + eap->length = htons(len); + eap->type = EAP_MSCHAPV2; + eap->opcode = MSCHAPV2_CHALLENGE; + eap->ms_chapv2_id = this->mschapv2id; + set_ms_length(eap, len); + + cha = (eap_mschapv2_challenge_t*)eap->data; + cha->value_size = CHALLENGE_LEN; + memcpy(cha->challenge, this->challenge.ptr, this->challenge.len); + memcpy(cha->name, name, sizeof(MSCHAPV2_HOST_NAME) - 1); + + *out = eap_payload_create_data(chunk_create((void*) eap, len)); + return NEED_MORE; +} + +static bool get_nt_hash(private_eap_mschapv2_t *this, identification_t *me, + identification_t *other, chunk_t *nt_hash) +{ + shared_key_t *shared; + chunk_t password; + + /* try to find a stored NT_HASH first */ + shared = charon->credentials->get_shared(charon->credentials, + SHARED_NT_HASH, me, other); + if (shared ) + { + *nt_hash = chunk_clone(shared->get_key(shared)); + shared->destroy(shared); + return TRUE; + } + + /* fallback to plaintext password */ + shared = charon->credentials->get_shared(charon->credentials, + SHARED_EAP, me, other); + if (shared) + { + password = ascii_to_unicode(shared->get_key(shared)); + shared->destroy(shared); + + if (NtPasswordHash(password, nt_hash) == SUCCESS) + { + chunk_clear(&password); + return TRUE; + } + chunk_clear(&password); + } + return FALSE; +} + +/** + * Process MS-CHAPv2 Challenge Requests + */ +static status_t process_peer_challenge(private_eap_mschapv2_t *this, + eap_payload_t *in, eap_payload_t **out) +{ + rng_t *rng; + eap_mschapv2_header_t *eap; + eap_mschapv2_challenge_t *cha; + eap_mschapv2_response_t *res; + chunk_t data, peer_challenge, username, nt_hash; + u_int16_t len = RESPONSE_PAYLOAD_LEN; + + data = in->get_data(in); + eap = (eap_mschapv2_header_t*)data.ptr; + + /* the name MUST be at least one octet long */ + if (data.len < CHALLENGE_PAYLOAD_LEN + 1) + { + DBG1(DBG_IKE, "received invalid EAP-MS-CHAPv2 message: too short"); + return FAILED; + } + + cha = (eap_mschapv2_challenge_t*)eap->data; + + if (cha->value_size != CHALLENGE_LEN) + { + DBG1(DBG_IKE, "received invalid EAP-MS-CHAPv2 message: " + "invalid challenge size"); + return FAILED; + } + + this->mschapv2id = eap->ms_chapv2_id; + this->challenge = chunk_clone(chunk_create(cha->challenge, CHALLENGE_LEN)); + + rng = lib->crypto->create_rng(lib->crypto, RNG_WEAK); + if (!rng) + { + DBG1(DBG_IKE, "EAP-MS-CHAPv2 failed, no RNG"); + return FAILED; + } + peer_challenge = chunk_alloca(CHALLENGE_LEN); + rng->get_bytes(rng, CHALLENGE_LEN, peer_challenge.ptr); + rng->destroy(rng); + + if (!get_nt_hash(this, this->peer, this->server, &nt_hash)) + { + DBG1(DBG_IKE, "no EAP key found for hosts '%Y' - '%Y'", + this->server, this->peer); + return NOT_FOUND; + } + + username = extract_username(this->peer); + len += username.len; + + if (GenerateStuff(this, this->challenge, peer_challenge, + username, nt_hash) != SUCCESS) + { + DBG1(DBG_IKE, "EAP-MS-CHAPv2 generating NT-Response failed"); + chunk_clear(&nt_hash); + return FAILED; + } + chunk_clear(&nt_hash); + + eap = alloca(len); + eap->code = EAP_RESPONSE; + eap->identifier = this->identifier; + eap->length = htons(len); + eap->type = EAP_MSCHAPV2; + eap->opcode = MSCHAPV2_RESPONSE; + eap->ms_chapv2_id = this->mschapv2id; + set_ms_length(eap, len); + + res = (eap_mschapv2_response_t*)eap->data; + res->value_size = RESPONSE_LEN; + memset(&res->response, 0, RESPONSE_LEN); + memcpy(res->response.peer_challenge, peer_challenge.ptr, peer_challenge.len); + memcpy(res->response.nt_response, this->nt_response.ptr, this->nt_response.len); + + username = this->peer->get_encoding(this->peer); + memcpy(res->name, username.ptr, username.len); + + *out = eap_payload_create_data(chunk_create((void*) eap, len)); + return NEED_MORE; +} + +/** + * Process MS-CHAPv2 Success Requests + */ +static status_t process_peer_success(private_eap_mschapv2_t *this, + eap_payload_t *in, eap_payload_t **out) +{ + status_t status = FAILED; + enumerator_t *enumerator; + eap_mschapv2_header_t *eap; + chunk_t data, auth_string = chunk_empty; + char *message, *token, *msg = NULL; + int message_len; + u_int16_t len = SHORT_HEADER_LEN; + + data = in->get_data(in); + eap = (eap_mschapv2_header_t*)data.ptr; + + if (data.len < AUTH_RESPONSE_LEN) + { + DBG1(DBG_IKE, "received invalid EAP-MS-CHAPv2 message: too short"); + return FAILED; + } + + message_len = data.len - HEADER_LEN; + message = malloc(message_len + 1); + memcpy(message, eap->data, message_len); + message[message_len] = '\0'; + + /* S=<auth_string> M=<msg> */ + enumerator = enumerator_create_token(message, " ", " "); + while (enumerator->enumerate(enumerator, &token)) + { + if (strneq(token, "S=", 2)) + { + chunk_t hex; + token += 2; + if (strlen(token) != AUTH_RESPONSE_LEN - 2) + { + DBG1(DBG_IKE, "received invalid EAP-MS-CHAPv2 message: " + "invalid auth string"); + goto error; + } + hex = chunk_create(token, AUTH_RESPONSE_LEN - 2); + auth_string = chunk_from_hex(hex, NULL); + } + else if (strneq(token, "M=", 2)) + { + token += 2; + msg = strdup(token); + } + } + enumerator->destroy(enumerator); + + if (auth_string.ptr == NULL) + { + DBG1(DBG_IKE, "received invalid EAP-MS-CHAPv2 message: " + "auth string missing"); + goto error; + } + + if (!chunk_equals(this->auth_response, auth_string)) + { + DBG1(DBG_IKE, "EAP-MS-CHAPv2 verification failed"); + goto error; + } + + DBG1(DBG_IKE, "EAP-MS-CHAPv2 succeeded: '%s'", sanitize(msg)); + + eap = alloca(len); + eap->code = EAP_RESPONSE; + eap->identifier = this->identifier; + eap->length = htons(len); + eap->type = EAP_MSCHAPV2; + eap->opcode = MSCHAPV2_SUCCESS; + + *out = eap_payload_create_data(chunk_create((void*) eap, len)); + status = NEED_MORE; + +error: + chunk_free(&auth_string); + free(message); + free(msg); + return status; +} + +static status_t process_peer_failure(private_eap_mschapv2_t *this, + eap_payload_t *in, eap_payload_t **out) +{ + status_t status = FAILED; + enumerator_t *enumerator; + eap_mschapv2_header_t *eap; + chunk_t data; + char *message, *token, *msg = NULL; + int message_len, error, retryable; + chunk_t challenge = chunk_empty; + + data = in->get_data(in); + eap = (eap_mschapv2_header_t*)data.ptr; + + if (data.len < 3) /* we want at least an error code: E=e */ + { + DBG1(DBG_IKE, "received invalid EAP-MS-CHAPv2 message: too short"); + return FAILED; + } + + message_len = data.len - HEADER_LEN; + message = malloc(message_len + 1); + memcpy(message, eap->data, message_len); + message[message_len] = '\0'; + + /* E=eeeeeeeeee R=r C=cccccccccccccccccccccccccccccccc V=vvvvvvvvvv M=<msg> */ + enumerator = enumerator_create_token(message, " ", " "); + while (enumerator->enumerate(enumerator, &token)) + { + if (strneq(token, "E=", 2)) + { + token += 2; + error = atoi(token); + } + else if (strneq(token, "R=", 2)) + { + token += 2; + retryable = atoi(token); + } + else if (strneq(token, "C=", 2)) + { + chunk_t hex; + token += 2; + if (strlen(token) != 2 * CHALLENGE_LEN) + { + DBG1(DBG_IKE, "received invalid EAP-MS-CHAPv2 message:" + "invalid challenge"); + goto error; + } + hex = chunk_create(token, 2 * CHALLENGE_LEN); + challenge = chunk_from_hex(hex, NULL); + } + else if (strneq(token, "V=", 2)) + { + int version; + token += 2; + version = atoi(token); + } + else if (strneq(token, "M=", 2)) + { + token += 2; + msg = strdup(token); + } + } + enumerator->destroy(enumerator); + + DBG1(DBG_IKE, "EAP-MS-CHAPv2 failed with error %N: '%s'", + mschapv2_error_names, error, sanitize(msg)); + + /** + * at this point, if the error is retryable, we MAY retry the authentication + * or MAY send a Change Password packet. + * + * if the error is not retryable (or if we do neither of the above), we + * SHOULD send a Failure Response packet. + * windows clients don't do that, and since windows server 2008 r2 behaves + * pretty odd if we do send a Failure Response, we just don't send one + * either. windows 7 actually sends a delete notify (which, according to the + * logs, results in an error on windows server 2008 r2). + * + * btw, windows server 2008 r2 does not send non-retryable errors for e.g. + * a disabled account but returns the windows error code in a notify payload + * of type 12345. + */ + + status = FAILED; + +error: + chunk_free(&challenge); + free(message); + free(msg); + return status; +} + +/** + * Implementation of eap_method_t.process for the peer + */ +static status_t process_peer(private_eap_mschapv2_t *this, eap_payload_t *in, + eap_payload_t **out) +{ + chunk_t data; + eap_mschapv2_header_t *eap; + + this->identifier = in->get_identifier(in); + data = in->get_data(in); + if (data.len < SHORT_HEADER_LEN) + { + DBG1(DBG_IKE, "received invalid EAP-MS-CHAPv2 message"); + return FAILED; + } + + eap = (eap_mschapv2_header_t*)data.ptr; + + switch (eap->opcode) + { + case MSCHAPV2_CHALLENGE: + { + return process_peer_challenge(this, in, out); + } + case MSCHAPV2_SUCCESS: + { + return process_peer_success(this, in, out); + } + case MSCHAPV2_FAILURE: + { + return process_peer_failure(this, in, out); + } + default: + { + DBG1(DBG_IKE, "EAP-MS-CHAPv2 received packet with unsupported " + "OpCode (%N)!", mschapv2_opcode_names, eap->opcode); + break; + } + } + return FAILED; +} + +/** + * Handles retries on the server + */ +static status_t process_server_retry(private_eap_mschapv2_t *this, + eap_payload_t **out) +{ + eap_mschapv2_header_t *eap; + rng_t *rng; + chunk_t hex; + char msg[FAILURE_MESSAGE_LEN]; + u_int16_t len = HEADER_LEN + FAILURE_MESSAGE_LEN - 1; /* no null byte */ + + if (++this->retries > MAX_RETRIES) + { + /* we MAY send a Failure Request with R=0, but windows 7 does not + * really like that and does not respond with a Failure Response. + * so, to clean up our state we just fail with an EAP-Failure. + * this gives an unknown error on the windows side, but is also fine + * with the standard. */ + DBG1(DBG_IKE, "EAP-MS-CHAPv2 verification failed: " + "maximum number of retries reached"); + return FAILED; + } + + DBG1(DBG_IKE, "EAP-MS-CHAPv2 verification failed, retry (%d)", this->retries); + + rng = lib->crypto->create_rng(lib->crypto, RNG_WEAK); + if (!rng) + { + DBG1(DBG_IKE, "EAP-MS-CHAPv2 failed, no RNG"); + return FAILED; + } + rng->get_bytes(rng, CHALLENGE_LEN, this->challenge.ptr); + rng->destroy(rng); + + chunk_free(&this->nt_response); + chunk_free(&this->auth_response); + chunk_free(&this->msk); + + eap = alloca(len); + eap->code = EAP_REQUEST; + eap->identifier = ++this->identifier; + eap->length = htons(len); + eap->type = EAP_MSCHAPV2; + eap->opcode = MSCHAPV2_FAILURE; + eap->ms_chapv2_id = this->mschapv2id++; /* increase for each retry */ + set_ms_length(eap, len); + + hex = chunk_to_hex(this->challenge, NULL, TRUE); + snprintf(msg, FAILURE_MESSAGE_LEN, "%s%s", FAILURE_MESSAGE, hex.ptr); + chunk_free(&hex); + memcpy(eap->data, msg, FAILURE_MESSAGE_LEN - 1); /* no null byte */ + *out = eap_payload_create_data(chunk_create((void*) eap, len)); + + /* delay the response for some time to make brute-force attacks harder */ + sleep(RETRY_DELAY); + + return NEED_MORE; +} + +/** + * Process MS-CHAPv2 Response response packets + */ +static status_t process_server_response(private_eap_mschapv2_t *this, + eap_payload_t *in, eap_payload_t **out) +{ + eap_mschapv2_header_t *eap; + eap_mschapv2_response_t *res; + chunk_t data, peer_challenge, username, nt_hash; + identification_t *userid; + int name_len; + char buf[256]; + + data = in->get_data(in); + eap = (eap_mschapv2_header_t*)data.ptr; + + if (data.len < RESPONSE_PAYLOAD_LEN) + { + DBG1(DBG_IKE, "received invalid EAP-MS-CHAPv2 message: too short"); + return FAILED; + } + + res = (eap_mschapv2_response_t*)eap->data; + peer_challenge = chunk_create(res->response.peer_challenge, CHALLENGE_LEN); + + name_len = min(data.len - RESPONSE_PAYLOAD_LEN, 255); + snprintf(buf, sizeof(buf), "%.*s", name_len, res->name); + userid = identification_create_from_string(buf); + DBG2(DBG_IKE, "EAP-MS-CHAPv2 username: '%Y'", userid); + username = extract_username(userid); + + if (!get_nt_hash(this, this->server, userid, &nt_hash)) + { + DBG1(DBG_IKE, "no EAP key found for hosts '%Y' - '%Y'", + this->server, userid); + /* FIXME: windows 7 always sends the username that is first entered in + * the username box, even, if the user changes it during retries (probably + * to keep consistent with the EAP-Identity). + * thus, we could actually fail here, because retries do not make much + * sense. on the other hand, an attacker could guess usernames, if the + * error messages were different. */ + userid->destroy(userid); + return process_server_retry(this, out); + } + + if (GenerateStuff(this, this->challenge, peer_challenge, + username, nt_hash) != SUCCESS) + { + DBG1(DBG_IKE, "EAP-MS-CHAPv2 verification failed"); + userid->destroy(userid); + chunk_clear(&nt_hash); + return FAILED; + } + userid->destroy(userid); + chunk_clear(&nt_hash); + + if (memeq(res->response.nt_response, this->nt_response.ptr, + this->nt_response.len)) + { + chunk_t hex; + char msg[AUTH_RESPONSE_LEN + sizeof(SUCCESS_MESSAGE)]; + u_int16_t len = HEADER_LEN + AUTH_RESPONSE_LEN + sizeof(SUCCESS_MESSAGE); + + eap = alloca(len); + eap->code = EAP_REQUEST; + eap->identifier = ++this->identifier; + eap->length = htons(len); + eap->type = EAP_MSCHAPV2; + eap->opcode = MSCHAPV2_SUCCESS; + eap->ms_chapv2_id = this->mschapv2id; + set_ms_length(eap, len); + + hex = chunk_to_hex(this->auth_response, NULL, TRUE); + snprintf(msg, AUTH_RESPONSE_LEN + sizeof(SUCCESS_MESSAGE), + "S=%s%s", hex.ptr, SUCCESS_MESSAGE); + chunk_free(&hex); + memcpy(eap->data, msg, AUTH_RESPONSE_LEN + sizeof(SUCCESS_MESSAGE)); + *out = eap_payload_create_data(chunk_create((void*) eap, len)); + return NEED_MORE; + } + + return process_server_retry(this, out); +} + +/** + * Implementation of eap_method_t.process for the server + */ +static status_t process_server(private_eap_mschapv2_t *this, eap_payload_t *in, + eap_payload_t **out) +{ + eap_mschapv2_header_t *eap; + chunk_t data; + + if (this->identifier != in->get_identifier(in)) + { + DBG1(DBG_IKE, "received invalid EAP-MS-CHAPv2 message: " + "unexpected identifier"); + return FAILED; + } + + data = in->get_data(in); + if (data.len < SHORT_HEADER_LEN) + { + DBG1(DBG_IKE, "received invalid EAP-MS-CHAPv2 message: too short"); + return FAILED; + } + + eap = (eap_mschapv2_header_t*)data.ptr; + + switch (eap->opcode) + { + case MSCHAPV2_RESPONSE: + { + return process_server_response(this, in, out); + } + case MSCHAPV2_SUCCESS: + { + return SUCCESS; + } + case MSCHAPV2_FAILURE: + { + return FAILED; + } + default: + { + DBG1(DBG_IKE, "EAP-MS-CHAPv2 received packet with unsupported " + "OpCode (%N)!", mschapv2_opcode_names, eap->opcode); + break; + } + } + return FAILED; +} + +/** + * Implementation of eap_method_t.get_type. + */ +static eap_type_t get_type(private_eap_mschapv2_t *this, u_int32_t *vendor) +{ + *vendor = 0; + return EAP_MSCHAPV2; +} + +/** + * Implementation of eap_method_t.get_msk. + */ +static status_t get_msk(private_eap_mschapv2_t *this, chunk_t *msk) +{ + if (this->msk.ptr) + { + *msk = this->msk; + return SUCCESS; + } + return FAILED; +} + +/** + * Implementation of eap_method_t.is_mutual. + */ +static bool is_mutual(private_eap_mschapv2_t *this) +{ + return FALSE; +} + +/** + * Implementation of eap_method_t.destroy. + */ +static void destroy(private_eap_mschapv2_t *this) +{ + this->peer->destroy(this->peer); + this->server->destroy(this->server); + chunk_free(&this->challenge); + chunk_free(&this->nt_response); + chunk_free(&this->auth_response); + chunk_free(&this->msk); + free(this); +} + +/** + * Generic constructor + */ +static private_eap_mschapv2_t *eap_mschapv2_create_generic(identification_t *server, identification_t *peer) +{ + private_eap_mschapv2_t *this = malloc_thing(private_eap_mschapv2_t); + + this->public.eap_method_interface.initiate = NULL; + this->public.eap_method_interface.process = NULL; + this->public.eap_method_interface.get_type = (eap_type_t(*)(eap_method_t*,u_int32_t*))get_type; + this->public.eap_method_interface.is_mutual = (bool(*)(eap_method_t*))is_mutual; + this->public.eap_method_interface.get_msk = (status_t(*)(eap_method_t*,chunk_t*))get_msk; + this->public.eap_method_interface.destroy = (void(*)(eap_method_t*))destroy; + + /* private data */ + this->peer = peer->clone(peer); + this->server = server->clone(server); + this->challenge = chunk_empty; + this->nt_response = chunk_empty; + this->auth_response = chunk_empty; + this->msk = chunk_empty; + this->identifier = 0; + this->mschapv2id = 0; + this->retries = 0; + + return this; +} + +/* + * see header + */ +eap_mschapv2_t *eap_mschapv2_create_server(identification_t *server, identification_t *peer) +{ + private_eap_mschapv2_t *this = eap_mschapv2_create_generic(server, peer); + + this->public.eap_method_interface.initiate = (status_t(*)(eap_method_t*,eap_payload_t**))initiate_server; + this->public.eap_method_interface.process = (status_t(*)(eap_method_t*,eap_payload_t*, eap_payload_t**))process_server; + + /* generate a non-zero identifier */ + do + { + this->identifier = random(); + } while (!this->identifier); + + this->mschapv2id = this->identifier; + + return &this->public; +} + +/* + * see header + */ +eap_mschapv2_t *eap_mschapv2_create_peer(identification_t *server, identification_t *peer) +{ + private_eap_mschapv2_t *this = eap_mschapv2_create_generic(server, peer); + + this->public.eap_method_interface.initiate = (status_t(*)(eap_method_t*,eap_payload_t**))initiate_peer; + this->public.eap_method_interface.process = (status_t(*)(eap_method_t*,eap_payload_t*, eap_payload_t**))process_peer; + + return &this->public; +} + |