/* * hostapd / EAP-pwd (RFC 5931) server * Copyright (c) 2010, Dan Harkins * * This software may be distributed under the terms of the BSD license. * See README for more details. */ #include "includes.h" #include "common.h" #include "crypto/sha256.h" #include "eap_server/eap_i.h" #include "eap_common/eap_pwd_common.h" struct eap_pwd_data { enum { PWD_ID_Req, PWD_Commit_Req, PWD_Confirm_Req, SUCCESS, FAILURE } state; u8 *id_peer; size_t id_peer_len; u8 *id_server; size_t id_server_len; u8 *password; size_t password_len; u32 token; u16 group_num; EAP_PWD_group *grp; struct wpabuf *inbuf; size_t in_frag_pos; struct wpabuf *outbuf; size_t out_frag_pos; size_t mtu; BIGNUM *k; BIGNUM *private_value; BIGNUM *peer_scalar; BIGNUM *my_scalar; EC_POINT *my_element; EC_POINT *peer_element; u8 my_confirm[SHA256_MAC_LEN]; u8 msk[EAP_MSK_LEN]; u8 emsk[EAP_EMSK_LEN]; u8 session_id[1 + SHA256_MAC_LEN]; BN_CTX *bnctx; }; static const char * eap_pwd_state_txt(int state) { switch (state) { case PWD_ID_Req: return "PWD-ID-Req"; case PWD_Commit_Req: return "PWD-Commit-Req"; case PWD_Confirm_Req: return "PWD-Confirm-Req"; case SUCCESS: return "SUCCESS"; case FAILURE: return "FAILURE"; default: return "PWD-Unk"; } } static void eap_pwd_state(struct eap_pwd_data *data, int state) { wpa_printf(MSG_DEBUG, "EAP-pwd: %s -> %s", eap_pwd_state_txt(data->state), eap_pwd_state_txt(state)); data->state = state; } static void * eap_pwd_init(struct eap_sm *sm) { struct eap_pwd_data *data; if (sm->user == NULL || sm->user->password == NULL || sm->user->password_len == 0) { wpa_printf(MSG_INFO, "EAP-PWD (server): Password is not " "configured"); return NULL; } data = os_zalloc(sizeof(*data)); if (data == NULL) return NULL; data->group_num = sm->pwd_group; wpa_printf(MSG_DEBUG, "EAP-pwd: Selected group number %d", data->group_num); data->state = PWD_ID_Req; data->id_server = (u8 *) os_strdup("server"); if (data->id_server) data->id_server_len = os_strlen((char *) data->id_server); data->password = os_malloc(sm->user->password_len); if (data->password == NULL) { wpa_printf(MSG_INFO, "EAP-PWD: Memory allocation password " "fail"); bin_clear_free(data->id_server, data->id_server_len); os_free(data); return NULL; } data->password_len = sm->user->password_len; os_memcpy(data->password, sm->user->password, data->password_len); data->bnctx = BN_CTX_new(); if (data->bnctx == NULL) { wpa_printf(MSG_INFO, "EAP-PWD: bn context allocation fail"); bin_clear_free(data->password, data->password_len); bin_clear_free(data->id_server, data->id_server_len); os_free(data); return NULL; } data->in_frag_pos = data->out_frag_pos = 0; data->inbuf = data->outbuf = NULL; /* use default MTU from RFC 5931 if not configured otherwise */ data->mtu = sm->fragment_size > 0 ? sm->fragment_size : 1020; return data; } static void eap_pwd_reset(struct eap_sm *sm, void *priv) { struct eap_pwd_data *data = priv; BN_clear_free(data->private_value); BN_clear_free(data->peer_scalar); BN_clear_free(data->my_scalar); BN_clear_free(data->k); BN_CTX_free(data->bnctx); EC_POINT_clear_free(data->my_element); EC_POINT_clear_free(data->peer_element); bin_clear_free(data->id_peer, data->id_peer_len); bin_clear_free(data->id_server, data->id_server_len); bin_clear_free(data->password, data->password_len); if (data->grp) { EC_GROUP_free(data->grp->group); EC_POINT_clear_free(data->grp->pwe); BN_clear_free(data->grp->order); BN_clear_free(data->grp->prime); os_free(data->grp); } wpabuf_free(data->inbuf); wpabuf_free(data->outbuf); bin_clear_free(data, sizeof(*data)); } static void eap_pwd_build_id_req(struct eap_sm *sm, struct eap_pwd_data *data, u8 id) { wpa_printf(MSG_DEBUG, "EAP-pwd: ID/Request"); /* * if we're fragmenting then we already have an id request, just return */ if (data->out_frag_pos) return; data->outbuf = wpabuf_alloc(sizeof(struct eap_pwd_id) + data->id_server_len); if (data->outbuf == NULL) { eap_pwd_state(data, FAILURE); return; } /* an lfsr is good enough to generate unpredictable tokens */ data->token = os_random(); wpabuf_put_be16(data->outbuf, data->group_num); wpabuf_put_u8(data->outbuf, EAP_PWD_DEFAULT_RAND_FUNC); wpabuf_put_u8(data->outbuf, EAP_PWD_DEFAULT_PRF); wpabuf_put_data(data->outbuf, &data->token, sizeof(data->token)); wpabuf_put_u8(data->outbuf, EAP_PWD_PREP_NONE); wpabuf_put_data(data->outbuf, data->id_server, data->id_server_len); } static void eap_pwd_build_commit_req(struct eap_sm *sm, struct eap_pwd_data *data, u8 id) { BIGNUM *mask = NULL, *x = NULL, *y = NULL; u8 *scalar = NULL, *element = NULL; u16 offset; wpa_printf(MSG_DEBUG, "EAP-pwd: Commit/Request"); /* * if we're fragmenting then we already have an commit request, just * return */ if (data->out_frag_pos) return; if (((data->private_value = BN_new()) == NULL) || ((data->my_element = EC_POINT_new(data->grp->group)) == NULL) || ((data->my_scalar = BN_new()) == NULL) || ((mask = BN_new()) == NULL)) { wpa_printf(MSG_INFO, "EAP-PWD (server): scalar allocation " "fail"); goto fin; } if (BN_rand_range(data->private_value, data->grp->order) != 1 || BN_rand_range(mask, data->grp->order) != 1 || BN_add(data->my_scalar, data->private_value, mask) != 1 || BN_mod(data->my_scalar, data->my_scalar, data->grp->order, data->bnctx) != 1) { wpa_printf(MSG_INFO, "EAP-pwd (server): unable to get randomness"); goto fin; } if (!EC_POINT_mul(data->grp->group, data->my_element, NULL, data->grp->pwe, mask, data->bnctx)) { wpa_printf(MSG_INFO, "EAP-PWD (server): element allocation " "fail"); eap_pwd_state(data, FAILURE); goto fin; } if (!EC_POINT_invert(data->grp->group, data->my_element, data->bnctx)) { wpa_printf(MSG_INFO, "EAP-PWD (server): element inversion " "fail"); goto fin; } BN_clear_free(mask); if (((x = BN_new()) == NULL) || ((y = BN_new()) == NULL)) { wpa_printf(MSG_INFO, "EAP-PWD (server): point allocation " "fail"); goto fin; } if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group, data->my_element, x, y, data->bnctx)) { wpa_printf(MSG_INFO, "EAP-PWD (server): point assignment " "fail"); goto fin; } if (((scalar = os_malloc(BN_num_bytes(data->grp->order))) == NULL) || ((element = os_malloc(BN_num_bytes(data->grp->prime) * 2)) == NULL)) { wpa_printf(MSG_INFO, "EAP-PWD (server): data allocation fail"); goto fin; } /* * bignums occupy as little memory as possible so one that is * sufficiently smaller than the prime or order might need pre-pending * with zeros. */ os_memset(scalar, 0, BN_num_bytes(data->grp->order)); os_memset(element, 0, BN_num_bytes(data->grp->prime) * 2); offset = BN_num_bytes(data->grp->order) - BN_num_bytes(data->my_scalar); BN_bn2bin(data->my_scalar, scalar + offset); offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(x); BN_bn2bin(x, element + offset); offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(y); BN_bn2bin(y, element + BN_num_bytes(data->grp->prime) + offset); data->outbuf = wpabuf_alloc(2 * BN_num_bytes(data->grp->prime) + BN_num_bytes(data->grp->order)); if (data->outbuf == NULL) goto fin; /* We send the element as (x,y) followed by the scalar */ wpabuf_put_data(data->outbuf, element, 2 * BN_num_bytes(data->grp->prime)); wpabuf_put_data(data->outbuf, scalar, BN_num_bytes(data->grp->order)); fin: os_free(scalar); os_free(element); BN_clear_free(x); BN_clear_free(y); if (data->outbuf == NULL) eap_pwd_state(data, FAILURE); } static void eap_pwd_build_confirm_req(struct eap_sm *sm, struct eap_pwd_data *data, u8 id) { BIGNUM *x = NULL, *y = NULL; struct crypto_hash *hash; u8 conf[SHA256_MAC_LEN], *cruft = NULL, *ptr; u16 grp; int offset; wpa_printf(MSG_DEBUG, "EAP-pwd: Confirm/Request"); /* * if we're fragmenting then we already have an confirm request, just * return */ if (data->out_frag_pos) return; /* Each component of the cruft will be at most as big as the prime */ if (((cruft = os_malloc(BN_num_bytes(data->grp->prime))) == NULL) || ((x = BN_new()) == NULL) || ((y = BN_new()) == NULL)) { wpa_printf(MSG_INFO, "EAP-PWD (server): debug allocation " "fail"); goto fin; } /* * commit is H(k | server_element | server_scalar | peer_element | * peer_scalar | ciphersuite) */ hash = eap_pwd_h_init(); if (hash == NULL) goto fin; /* * Zero the memory each time because this is mod prime math and some * value may start with a few zeros and the previous one did not. * * First is k */ os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(data->k); BN_bn2bin(data->k, cruft + offset); eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime)); /* server element: x, y */ if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group, data->my_element, x, y, data->bnctx)) { wpa_printf(MSG_INFO, "EAP-PWD (server): confirm point " "assignment fail"); goto fin; } os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(x); BN_bn2bin(x, cruft + offset); eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime)); os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(y); BN_bn2bin(y, cruft + offset); eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime)); /* server scalar */ os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); offset = BN_num_bytes(data->grp->order) - BN_num_bytes(data->my_scalar); BN_bn2bin(data->my_scalar, cruft + offset); eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->order)); /* peer element: x, y */ if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group, data->peer_element, x, y, data->bnctx)) { wpa_printf(MSG_INFO, "EAP-PWD (server): confirm point " "assignment fail"); goto fin; } os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(x); BN_bn2bin(x, cruft + offset); eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime)); os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(y); BN_bn2bin(y, cruft + offset); eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime)); /* peer scalar */ os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); offset = BN_num_bytes(data->grp->order) - BN_num_bytes(data->peer_scalar); BN_bn2bin(data->peer_scalar, cruft + offset); eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->order)); /* ciphersuite */ grp = htons(data->group_num); os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); ptr = cruft; os_memcpy(ptr, &grp, sizeof(u16)); ptr += sizeof(u16); *ptr = EAP_PWD_DEFAULT_RAND_FUNC; ptr += sizeof(u8); *ptr = EAP_PWD_DEFAULT_PRF; ptr += sizeof(u8); eap_pwd_h_update(hash, cruft, ptr - cruft); /* all done with the random function */ eap_pwd_h_final(hash, conf); os_memcpy(data->my_confirm, conf, SHA256_MAC_LEN); data->outbuf = wpabuf_alloc(SHA256_MAC_LEN); if (data->outbuf == NULL) goto fin; wpabuf_put_data(data->outbuf, conf, SHA256_MAC_LEN); fin: bin_clear_free(cruft, BN_num_bytes(data->grp->prime)); BN_clear_free(x); BN_clear_free(y); if (data->outbuf == NULL) eap_pwd_state(data, FAILURE); } static struct wpabuf * eap_pwd_build_req(struct eap_sm *sm, void *priv, u8 id) { struct eap_pwd_data *data = priv; struct wpabuf *req; u8 lm_exch; const u8 *buf; u16 totlen = 0; size_t len; /* * if we're buffering response fragments then just ACK */ if (data->in_frag_pos) { wpa_printf(MSG_DEBUG, "EAP-pwd: ACKing a fragment!!"); req = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_PWD, EAP_PWD_HDR_SIZE, EAP_CODE_REQUEST, id); if (req == NULL) { eap_pwd_state(data, FAILURE); return NULL; } switch (data->state) { case PWD_ID_Req: wpabuf_put_u8(req, EAP_PWD_OPCODE_ID_EXCH); break; case PWD_Commit_Req: wpabuf_put_u8(req, EAP_PWD_OPCODE_COMMIT_EXCH); break; case PWD_Confirm_Req: wpabuf_put_u8(req, EAP_PWD_OPCODE_CONFIRM_EXCH); break; default: eap_pwd_state(data, FAILURE); /* just to be sure */ wpabuf_free(req); return NULL; } return req; } /* * build the data portion of a request */ switch (data->state) { case PWD_ID_Req: eap_pwd_build_id_req(sm, data, id); lm_exch = EAP_PWD_OPCODE_ID_EXCH; break; case PWD_Commit_Req: eap_pwd_build_commit_req(sm, data, id); lm_exch = EAP_PWD_OPCODE_COMMIT_EXCH; break; case PWD_Confirm_Req: eap_pwd_build_confirm_req(sm, data, id); lm_exch = EAP_PWD_OPCODE_CONFIRM_EXCH; break; default: wpa_printf(MSG_INFO, "EAP-pwd: Unknown state %d in build_req", data->state); eap_pwd_state(data, FAILURE); lm_exch = 0; /* hush now, sweet compiler */ break; } if (data->state == FAILURE) return NULL; /* * determine whether that data needs to be fragmented */ len = wpabuf_len(data->outbuf) - data->out_frag_pos; if ((len + EAP_PWD_HDR_SIZE) > data->mtu) { len = data->mtu - EAP_PWD_HDR_SIZE; EAP_PWD_SET_MORE_BIT(lm_exch); /* * if this is the first fragment, need to set the M bit * and add the total length to the eap_pwd_hdr */ if (data->out_frag_pos == 0) { EAP_PWD_SET_LENGTH_BIT(lm_exch); totlen = wpabuf_len(data->outbuf) + EAP_PWD_HDR_SIZE + sizeof(u16); len -= sizeof(u16); wpa_printf(MSG_DEBUG, "EAP-pwd: Fragmenting output, " "total length = %d", totlen); } wpa_printf(MSG_DEBUG, "EAP-pwd: Send a %d byte fragment", (int) len); } /* * alloc an eap request and populate it with the data */ req = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_PWD, EAP_PWD_HDR_SIZE + len + (totlen ? sizeof(u16) : 0), EAP_CODE_REQUEST, id); if (req == NULL) { eap_pwd_state(data, FAILURE); return NULL; } wpabuf_put_u8(req, lm_exch); if (EAP_PWD_GET_LENGTH_BIT(lm_exch)) wpabuf_put_be16(req, totlen); buf = wpabuf_head_u8(data->outbuf); wpabuf_put_data(req, buf + data->out_frag_pos, len); data->out_frag_pos += len; /* * either not fragged or last fragment, either way free up the data */ if (data->out_frag_pos >= wpabuf_len(data->outbuf)) { wpabuf_free(data->outbuf); data->outbuf = NULL; data->out_frag_pos = 0; } return req; } static Boolean eap_pwd_check(struct eap_sm *sm, void *priv, struct wpabuf *respData) { struct eap_pwd_data *data = priv; const u8 *pos; size_t len; pos = eap_hdr_validate(EAP_VENDOR_IETF, EAP_TYPE_PWD, respData, &len); if (pos == NULL || len < 1) { wpa_printf(MSG_INFO, "EAP-pwd: Invalid frame"); return TRUE; } wpa_printf(MSG_DEBUG, "EAP-pwd: Received frame: exch = %d, len = %d", EAP_PWD_GET_EXCHANGE(*pos), (int) len); if (data->state == PWD_ID_Req && ((EAP_PWD_GET_EXCHANGE(*pos)) == EAP_PWD_OPCODE_ID_EXCH)) return FALSE; if (data->state == PWD_Commit_Req && ((EAP_PWD_GET_EXCHANGE(*pos)) == EAP_PWD_OPCODE_COMMIT_EXCH)) return FALSE; if (data->state == PWD_Confirm_Req && ((EAP_PWD_GET_EXCHANGE(*pos)) == EAP_PWD_OPCODE_CONFIRM_EXCH)) return FALSE; wpa_printf(MSG_INFO, "EAP-pwd: Unexpected opcode=%d in state=%d", *pos, data->state); return TRUE; } static void eap_pwd_process_id_resp(struct eap_sm *sm, struct eap_pwd_data *data, const u8 *payload, size_t payload_len) { struct eap_pwd_id *id; if (payload_len < sizeof(struct eap_pwd_id)) { wpa_printf(MSG_INFO, "EAP-pwd: Invalid ID response"); return; } id = (struct eap_pwd_id *) payload; if ((data->group_num != be_to_host16(id->group_num)) || (id->random_function != EAP_PWD_DEFAULT_RAND_FUNC) || (os_memcmp(id->token, (u8 *)&data->token, sizeof(data->token))) || (id->prf != EAP_PWD_DEFAULT_PRF)) { wpa_printf(MSG_INFO, "EAP-pwd: peer changed parameters"); eap_pwd_state(data, FAILURE); return; } data->id_peer = os_malloc(payload_len - sizeof(struct eap_pwd_id)); if (data->id_peer == NULL) { wpa_printf(MSG_INFO, "EAP-PWD: memory allocation id fail"); return; } data->id_peer_len = payload_len - sizeof(struct eap_pwd_id); os_memcpy(data->id_peer, id->identity, data->id_peer_len); wpa_hexdump_ascii(MSG_DEBUG, "EAP-PWD (server): peer sent id of", data->id_peer, data->id_peer_len); data->grp = os_zalloc(sizeof(EAP_PWD_group)); if (data->grp == NULL) { wpa_printf(MSG_INFO, "EAP-PWD: failed to allocate memory for " "group"); return; } if (compute_password_element(data->grp, data->group_num, data->password, data->password_len, data->id_server, data->id_server_len, data->id_peer, data->id_peer_len, (u8 *) &data->token)) { wpa_printf(MSG_INFO, "EAP-PWD (server): unable to compute " "PWE"); return; } wpa_printf(MSG_DEBUG, "EAP-PWD (server): computed %d bit PWE...", BN_num_bits(data->grp->prime)); eap_pwd_state(data, PWD_Commit_Req); } static void eap_pwd_process_commit_resp(struct eap_sm *sm, struct eap_pwd_data *data, const u8 *payload, size_t payload_len) { u8 *ptr; BIGNUM *x = NULL, *y = NULL, *cofactor = NULL; EC_POINT *K = NULL, *point = NULL; int res = 0; wpa_printf(MSG_DEBUG, "EAP-pwd: Received commit response"); if (((data->peer_scalar = BN_new()) == NULL) || ((data->k = BN_new()) == NULL) || ((cofactor = BN_new()) == NULL) || ((x = BN_new()) == NULL) || ((y = BN_new()) == NULL) || ((point = EC_POINT_new(data->grp->group)) == NULL) || ((K = EC_POINT_new(data->grp->group)) == NULL) || ((data->peer_element = EC_POINT_new(data->grp->group)) == NULL)) { wpa_printf(MSG_INFO, "EAP-PWD (server): peer data allocation " "fail"); goto fin; } if (!EC_GROUP_get_cofactor(data->grp->group, cofactor, NULL)) { wpa_printf(MSG_INFO, "EAP-PWD (server): unable to get " "cofactor for curve"); goto fin; } /* element, x then y, followed by scalar */ ptr = (u8 *) payload; BN_bin2bn(ptr, BN_num_bytes(data->grp->prime), x); ptr += BN_num_bytes(data->grp->prime); BN_bin2bn(ptr, BN_num_bytes(data->grp->prime), y); ptr += BN_num_bytes(data->grp->prime); BN_bin2bn(ptr, BN_num_bytes(data->grp->order), data->peer_scalar); if (!EC_POINT_set_affine_coordinates_GFp(data->grp->group, data->peer_element, x, y, data->bnctx)) { wpa_printf(MSG_INFO, "EAP-PWD (server): setting peer element " "fail"); goto fin; } /* check to ensure peer's element is not in a small sub-group */ if (BN_cmp(cofactor, BN_value_one())) { if (!EC_POINT_mul(data->grp->group, point, NULL, data->peer_element, cofactor, NULL)) { wpa_printf(MSG_INFO, "EAP-PWD (server): cannot " "multiply peer element by order"); goto fin; } if (EC_POINT_is_at_infinity(data->grp->group, point)) { wpa_printf(MSG_INFO, "EAP-PWD (server): peer element " "is at infinity!\n"); goto fin; } } /* compute the shared key, k */ if ((!EC_POINT_mul(data->grp->group, K, NULL, data->grp->pwe, data->peer_scalar, data->bnctx)) || (!EC_POINT_add(data->grp->group, K, K, data->peer_element, data->bnctx)) || (!EC_POINT_mul(data->grp->group, K, NULL, K, data->private_value, data->bnctx))) { wpa_printf(MSG_INFO, "EAP-PWD (server): computing shared key " "fail"); goto fin; } /* ensure that the shared key isn't in a small sub-group */ if (BN_cmp(cofactor, BN_value_one())) { if (!EC_POINT_mul(data->grp->group, K, NULL, K, cofactor, NULL)) { wpa_printf(MSG_INFO, "EAP-PWD (server): cannot " "multiply shared key point by order!\n"); goto fin; } } /* * This check is strictly speaking just for the case above where * co-factor > 1 but it was suggested that even though this is probably * never going to happen it is a simple and safe check "just to be * sure" so let's be safe. */ if (EC_POINT_is_at_infinity(data->grp->group, K)) { wpa_printf(MSG_INFO, "EAP-PWD (server): shared key point is " "at infinity"); goto fin; } if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group, K, data->k, NULL, data->bnctx)) { wpa_printf(MSG_INFO, "EAP-PWD (server): unable to extract " "shared secret from secret point"); goto fin; } res = 1; fin: EC_POINT_clear_free(K); EC_POINT_clear_free(point); BN_clear_free(cofactor); BN_clear_free(x); BN_clear_free(y); if (res) eap_pwd_state(data, PWD_Confirm_Req); else eap_pwd_state(data, FAILURE); } static void eap_pwd_process_confirm_resp(struct eap_sm *sm, struct eap_pwd_data *data, const u8 *payload, size_t payload_len) { BIGNUM *x = NULL, *y = NULL; struct crypto_hash *hash; u32 cs; u16 grp; u8 conf[SHA256_MAC_LEN], *cruft = NULL, *ptr; int offset; /* build up the ciphersuite: group | random_function | prf */ grp = htons(data->group_num); ptr = (u8 *) &cs; os_memcpy(ptr, &grp, sizeof(u16)); ptr += sizeof(u16); *ptr = EAP_PWD_DEFAULT_RAND_FUNC; ptr += sizeof(u8); *ptr = EAP_PWD_DEFAULT_PRF; /* each component of the cruft will be at most as big as the prime */ if (((cruft = os_malloc(BN_num_bytes(data->grp->prime))) == NULL) || ((x = BN_new()) == NULL) || ((y = BN_new()) == NULL)) { wpa_printf(MSG_INFO, "EAP-PWD (peer): allocation fail"); goto fin; } /* * commit is H(k | peer_element | peer_scalar | server_element | * server_scalar | ciphersuite) */ hash = eap_pwd_h_init(); if (hash == NULL) goto fin; /* k */ os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(data->k); BN_bn2bin(data->k, cruft + offset); eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime)); /* peer element: x, y */ if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group, data->peer_element, x, y, data->bnctx)) { wpa_printf(MSG_INFO, "EAP-PWD (server): confirm point " "assignment fail"); goto fin; } os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(x); BN_bn2bin(x, cruft + offset); eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime)); os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(y); BN_bn2bin(y, cruft + offset); eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime)); /* peer scalar */ os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); offset = BN_num_bytes(data->grp->order) - BN_num_bytes(data->peer_scalar); BN_bn2bin(data->peer_scalar, cruft + offset); eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->order)); /* server element: x, y */ if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group, data->my_element, x, y, data->bnctx)) { wpa_printf(MSG_INFO, "EAP-PWD (server): confirm point " "assignment fail"); goto fin; } os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(x); BN_bn2bin(x, cruft + offset); eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime)); os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(y); BN_bn2bin(y, cruft + offset); eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime)); /* server scalar */ os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); offset = BN_num_bytes(data->grp->order) - BN_num_bytes(data->my_scalar); BN_bn2bin(data->my_scalar, cruft + offset); eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->order)); /* ciphersuite */ os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); eap_pwd_h_update(hash, (u8 *) &cs, sizeof(u32)); /* all done */ eap_pwd_h_final(hash, conf); ptr = (u8 *) payload; if (os_memcmp_const(conf, ptr, SHA256_MAC_LEN)) { wpa_printf(MSG_INFO, "EAP-PWD (server): confirm did not " "verify"); goto fin; } wpa_printf(MSG_DEBUG, "EAP-pwd (server): confirm verified"); if (compute_keys(data->grp, data->bnctx, data->k, data->peer_scalar, data->my_scalar, conf, data->my_confirm, &cs, data->msk, data->emsk, data->session_id) < 0) eap_pwd_state(data, FAILURE); else eap_pwd_state(data, SUCCESS); fin: bin_clear_free(cruft, BN_num_bytes(data->grp->prime)); BN_clear_free(x); BN_clear_free(y); } static void eap_pwd_process(struct eap_sm *sm, void *priv, struct wpabuf *respData) { struct eap_pwd_data *data = priv; const u8 *pos; size_t len; u8 lm_exch; u16 tot_len; pos = eap_hdr_validate(EAP_VENDOR_IETF, EAP_TYPE_PWD, respData, &len); if ((pos == NULL) || (len < 1)) { wpa_printf(MSG_INFO, "Bad EAP header! pos %s and len = %d", (pos == NULL) ? "is NULL" : "is not NULL", (int) len); return; } lm_exch = *pos; pos++; /* skip over the bits and the exch */ len--; /* * if we're fragmenting then this should be an ACK with no data, * just return and continue fragmenting in the "build" section above */ if (data->out_frag_pos) { if (len > 1) wpa_printf(MSG_INFO, "EAP-pwd: Bad response! " "Fragmenting but not an ACK"); else wpa_printf(MSG_DEBUG, "EAP-pwd: received ACK from " "peer"); return; } /* * if we're receiving fragmented packets then we need to buffer... * * the first fragment has a total length */ if (EAP_PWD_GET_LENGTH_BIT(lm_exch)) { tot_len = WPA_GET_BE16(pos); wpa_printf(MSG_DEBUG, "EAP-pwd: Incoming fragments, total " "length = %d", tot_len); if (tot_len > 15000) return; data->inbuf = wpabuf_alloc(tot_len); if (data->inbuf == NULL) { wpa_printf(MSG_INFO, "EAP-pwd: Out of memory to " "buffer fragments!"); return; } pos += sizeof(u16); len -= sizeof(u16); } /* * the first and all intermediate fragments have the M bit set */ if (EAP_PWD_GET_MORE_BIT(lm_exch)) { if ((data->in_frag_pos + len) > wpabuf_size(data->inbuf)) { wpa_printf(MSG_DEBUG, "EAP-pwd: Buffer overflow " "attack detected! (%d+%d > %d)", (int) data->in_frag_pos, (int) len, (int) wpabuf_size(data->inbuf)); eap_pwd_state(data, FAILURE); return; } wpabuf_put_data(data->inbuf, pos, len); data->in_frag_pos += len; wpa_printf(MSG_DEBUG, "EAP-pwd: Got a %d byte fragment", (int) len); return; } /* * last fragment won't have the M bit set (but we're obviously * buffering fragments so that's how we know it's the last) */ if (data->in_frag_pos) { wpabuf_put_data(data->inbuf, pos, len); data->in_frag_pos += len; pos = wpabuf_head_u8(data->inbuf); len = data->in_frag_pos; wpa_printf(MSG_DEBUG, "EAP-pwd: Last fragment, %d bytes", (int) len); } switch (EAP_PWD_GET_EXCHANGE(lm_exch)) { case EAP_PWD_OPCODE_ID_EXCH: eap_pwd_process_id_resp(sm, data, pos, len); break; case EAP_PWD_OPCODE_COMMIT_EXCH: eap_pwd_process_commit_resp(sm, data, pos, len); break; case EAP_PWD_OPCODE_CONFIRM_EXCH: eap_pwd_process_confirm_resp(sm, data, pos, len); break; } /* * if we had been buffering fragments, here's a great place * to clean up */ if (data->in_frag_pos) { wpabuf_free(data->inbuf); data->inbuf = NULL; data->in_frag_pos = 0; } } static u8 * eap_pwd_getkey(struct eap_sm *sm, void *priv, size_t *len) { struct eap_pwd_data *data = priv; u8 *key; if (data->state != SUCCESS) return NULL; key = os_malloc(EAP_MSK_LEN); if (key == NULL) return NULL; os_memcpy(key, data->msk, EAP_MSK_LEN); *len = EAP_MSK_LEN; return key; } static u8 * eap_pwd_get_emsk(struct eap_sm *sm, void *priv, size_t *len) { struct eap_pwd_data *data = priv; u8 *key; if (data->state != SUCCESS) return NULL; key = os_malloc(EAP_EMSK_LEN); if (key == NULL) return NULL; os_memcpy(key, data->emsk, EAP_EMSK_LEN); *len = EAP_EMSK_LEN; return key; } static Boolean eap_pwd_is_success(struct eap_sm *sm, void *priv) { struct eap_pwd_data *data = priv; return data->state == SUCCESS; } static Boolean eap_pwd_is_done(struct eap_sm *sm, void *priv) { struct eap_pwd_data *data = priv; return (data->state == SUCCESS) || (data->state == FAILURE); } int eap_server_pwd_register(void) { struct eap_method *eap; int ret; struct timeval tp; struct timezone tz; u32 sr; sr = 0xdeaddada; (void) gettimeofday(&tp, &tz); sr ^= (tp.tv_sec ^ tp.tv_usec); srandom(sr); eap = eap_server_method_alloc(EAP_SERVER_METHOD_INTERFACE_VERSION, EAP_VENDOR_IETF, EAP_TYPE_PWD, "PWD"); if (eap == NULL) return -1; eap->init = eap_pwd_init; eap->reset = eap_pwd_reset; eap->buildReq = eap_pwd_build_req; eap->check = eap_pwd_check; eap->process = eap_pwd_process; eap->isDone = eap_pwd_is_done; eap->getKey = eap_pwd_getkey; eap->get_emsk = eap_pwd_get_emsk; eap->isSuccess = eap_pwd_is_success; ret = eap_server_method_register(eap); if (ret) eap_server_method_free(eap); return ret; }