diff options
Diffstat (limited to 'contrib/wpa/src/eap_server/eap_server_pwd.c')
| -rw-r--r-- | contrib/wpa/src/eap_server/eap_server_pwd.c | 1045 |
1 files changed, 1045 insertions, 0 deletions
diff --git a/contrib/wpa/src/eap_server/eap_server_pwd.c b/contrib/wpa/src/eap_server/eap_server_pwd.c new file mode 100644 index 0000000..b61061b --- /dev/null +++ b/contrib/wpa/src/eap_server/eap_server_pwd.c @@ -0,0 +1,1045 @@ +/* + * hostapd / EAP-pwd (RFC 5931) server + * Copyright (c) 2010, Dan Harkins <dharkins@lounge.org> + * + * 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]; + + 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"); + os_free(data->id_server); + 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"); + os_free(data->password); + os_free(data->id_server); + os_free(data); + return NULL; + } + + data->in_frag_pos = data->out_frag_pos = 0; + data->inbuf = data->outbuf = NULL; + data->mtu = 1020; /* default from RFC 5931, make it configurable! */ + + return data; +} + + +static void eap_pwd_reset(struct eap_sm *sm, void *priv) +{ + struct eap_pwd_data *data = priv; + + BN_free(data->private_value); + BN_free(data->peer_scalar); + BN_free(data->my_scalar); + BN_free(data->k); + BN_CTX_free(data->bnctx); + EC_POINT_free(data->my_element); + EC_POINT_free(data->peer_element); + os_free(data->id_peer); + os_free(data->id_server); + os_free(data->password); + if (data->grp) { + EC_GROUP_free(data->grp->group); + EC_POINT_free(data->grp->pwe); + BN_free(data->grp->order); + BN_free(data->grp->prime); + os_free(data->grp); + } + os_free(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; + } + + BN_rand_range(data->private_value, data->grp->order); + BN_rand_range(mask, data->grp->order); + BN_add(data->my_scalar, data->private_value, mask); + BN_mod(data->my_scalar, data->my_scalar, data->grp->order, + data->bnctx); + + 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_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_free(x); + BN_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: + os_free(cruft); + BN_free(x); + BN_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->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); + + if ((data->grp = os_malloc(sizeof(EAP_PWD_group))) == 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_free(K); + EC_POINT_free(point); + BN_free(cofactor); + BN_free(x); + BN_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(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) < 0) + eap_pwd_state(data, FAILURE); + else + eap_pwd_state(data, SUCCESS); + +fin: + os_free(cruft); + BN_free(x); + BN_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); + 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->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; + + EVP_add_digest(EVP_sha256()); + + 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; +} + |
