src/eap_server/eap_server_tls_common.c

   1 /*
   2  * EAP-TLS/PEAP/TTLS/FAST server common functions
   3  * Copyright (c) 2004-2009, Jouni Malinen <j@w1.fi>
   4  *
   5  * This software may be distributed under the terms of the BSD license.
   6  * See README for more details.
   7  */
   8
   9 #include "includes.h"
  10
  11 #include "common.h"
  12 #include "crypto/sha1.h"
  13 #include "crypto/tls.h"
  14 #include "eap_i.h"
  15 #include "eap_tls_common.h"
  16
  17
  18 static void eap_server_tls_free_in_buf(struct eap_ssl_data *data);
  19
  20
  21 struct wpabuf * eap_tls_msg_alloc(EapType type, size_t payload_len,
  22                                   u8 code, u8 identifier)
  23 {
  24         if (type == EAP_UNAUTH_TLS_TYPE)
  25                 return eap_msg_alloc(EAP_VENDOR_UNAUTH_TLS,
  26                                      EAP_VENDOR_TYPE_UNAUTH_TLS, payload_len,
  27                                      code, identifier);
  28         else if (type == EAP_WFA_UNAUTH_TLS_TYPE)
  29                 return eap_msg_alloc(EAP_VENDOR_WFA_NEW,
  30                                      EAP_VENDOR_WFA_UNAUTH_TLS, payload_len,
  31                                      code, identifier);
  32         return eap_msg_alloc(EAP_VENDOR_IETF, type, payload_len, code,
  33                              identifier);
  34 }
  35
  36
  37 #ifdef CONFIG_TLS_INTERNAL
  38 static void eap_server_tls_log_cb(void *ctx, const char *msg)
  39 {
  40         struct eap_sm *sm = ctx;
  41         eap_log_msg(sm, "TLS: %s", msg);
  42 }
  43 #endif /* CONFIG_TLS_INTERNAL */
  44
  45
  46 int eap_server_tls_ssl_init(struct eap_sm *sm, struct eap_ssl_data *data,
  47                             int verify_peer, int eap_type)
  48 {
  49         u8 session_ctx[8];
  50         unsigned int flags = sm->tls_flags;
  51
  52         if (sm->ssl_ctx == NULL) {
  53                 wpa_printf(MSG_ERROR, "TLS context not initialized - cannot use TLS-based EAP method");
  54                 return -1;
  55         }
  56
  57         data->eap = sm;
  58         data->phase2 = sm->init_phase2;
  59
  60         data->conn = tls_connection_init(sm->ssl_ctx);
  61         if (data->conn == NULL) {
  62                 wpa_printf(MSG_INFO, "SSL: Failed to initialize new TLS "
  63                            "connection");
  64                 return -1;
  65         }
  66
  67 #ifdef CONFIG_TLS_INTERNAL
  68         tls_connection_set_log_cb(data->conn, eap_server_tls_log_cb, sm);
  69 #ifdef CONFIG_TESTING_OPTIONS
  70         tls_connection_set_test_flags(data->conn, sm->tls_test_flags);
  71 #endif /* CONFIG_TESTING_OPTIONS */
  72 #endif /* CONFIG_TLS_INTERNAL */
  73
  74         if (eap_type != EAP_TYPE_FAST)
  75                 flags |= TLS_CONN_DISABLE_SESSION_TICKET;
  76         os_memcpy(session_ctx, "hostapd", 7);
  77         session_ctx[7] = (u8) eap_type;
  78         if (tls_connection_set_verify(sm->ssl_ctx, data->conn, verify_peer,
  79                                       flags, session_ctx,
  80                                       sizeof(session_ctx))) {
  81                 wpa_printf(MSG_INFO, "SSL: Failed to configure verification "
  82                            "of TLS peer certificate");
  83                 tls_connection_deinit(sm->ssl_ctx, data->conn);
  84                 data->conn = NULL;
  85                 return -1;
  86         }
  87
  88         data->tls_out_limit = sm->fragment_size > 0 ? sm->fragment_size : 1398;
  89         if (data->phase2) {
  90                 /* Limit the fragment size in the inner TLS authentication
  91                  * since the outer authentication with EAP-PEAP does not yet
  92                  * support fragmentation */
  93                 if (data->tls_out_limit > 100)
  94                         data->tls_out_limit -= 100;
  95         }
  96         return 0;
  97 }
  98
  99
 100 void eap_server_tls_ssl_deinit(struct eap_sm *sm, struct eap_ssl_data *data)
 101 {
 102         tls_connection_deinit(sm->ssl_ctx, data->conn);
 103         eap_server_tls_free_in_buf(data);
 104         wpabuf_free(data->tls_out);
 105         data->tls_out = NULL;
 106 }
 107
 108
 109 u8 * eap_server_tls_derive_key(struct eap_sm *sm, struct eap_ssl_data *data,
 110                                const char *label, const u8 *context,
 111                                size_t context_len, size_t len)
 112 {
 113         u8 *out;
 114
 115         out = os_malloc(len);
 116         if (out == NULL)
 117                 return NULL;
 118
 119         if (tls_connection_export_key(sm->ssl_ctx, data->conn, label,
 120                                       context, context_len, out, len)) {
 121                 os_free(out);
 122                 return NULL;
 123         }
 124
 125         return out;
 126 }
 127
 128
 129 /**
 130  * eap_server_tls_derive_session_id - Derive a Session-Id based on TLS data
 131  * @sm: Pointer to EAP state machine allocated with eap_peer_sm_init()
 132  * @data: Data for TLS processing
 133  * @eap_type: EAP method used in Phase 1 (EAP_TYPE_TLS/PEAP/TTLS/FAST)
 134  * @len: Pointer to length of the session ID generated
 135  * Returns: Pointer to allocated Session-Id on success or %NULL on failure
 136  *
 137  * This function derive the Session-Id based on the TLS session data
 138  * (client/server random and method type).
 139  *
 140  * The caller is responsible for freeing the returned buffer.
 141  */
 142 u8 * eap_server_tls_derive_session_id(struct eap_sm *sm,
 143                                       struct eap_ssl_data *data, u8 eap_type,
 144                                       size_t *len)
 145 {
 146         struct tls_random keys;
 147         u8 *out;
 148
 149         if (eap_type == EAP_TYPE_TLS && data->tls_v13) {
 150                 u8 *id, *method_id;
 151
 152                 /* Session-Id = <EAP-Type> || Method-Id
 153                  * Method-Id = TLS-Exporter("EXPORTER_EAP_TLS_Method-Id",
 154                  *                          "", 64)
 155                  */
 156                 *len = 1 + 64;
 157                 id = os_malloc(*len);
 158                 if (!id)
 159                         return NULL;
 160                 method_id = eap_server_tls_derive_key(
 161                         sm, data, "EXPORTER_EAP_TLS_Method-Id", NULL, 0, 64);
 162                 if (!method_id) {
 163                         os_free(id);
 164                         return NULL;
 165                 }
 166                 id[0] = eap_type;
 167                 os_memcpy(id + 1, method_id, 64);
 168                 os_free(method_id);
 169                 return id;
 170         }
 171
 172         if (tls_connection_get_random(sm->ssl_ctx, data->conn, &keys))
 173                 return NULL;
 174
 175         if (keys.client_random == NULL || keys.server_random == NULL)
 176                 return NULL;
 177
 178         *len = 1 + keys.client_random_len + keys.server_random_len;
 179         out = os_malloc(*len);
 180         if (out == NULL)
 181                 return NULL;
 182
 183         /* Session-Id = EAP type || client.random || server.random */
 184         out[0] = eap_type;
 185         os_memcpy(out + 1, keys.client_random, keys.client_random_len);
 186         os_memcpy(out + 1 + keys.client_random_len, keys.server_random,
 187                   keys.server_random_len);
 188
 189         return out;
 190 }
 191
 192
 193 struct wpabuf * eap_server_tls_build_msg(struct eap_ssl_data *data,
 194                                          int eap_type, int version, u8 id)
 195 {
 196         struct wpabuf *req;
 197         u8 flags;
 198         size_t send_len, plen;
 199
 200         wpa_printf(MSG_DEBUG, "SSL: Generating Request");
 201         if (data->tls_out == NULL) {
 202                 wpa_printf(MSG_ERROR, "SSL: tls_out NULL in %s", __func__);
 203                 return NULL;
 204         }
 205
 206         flags = version;
 207         send_len = wpabuf_len(data->tls_out) - data->tls_out_pos;
 208         if (1 + send_len > data->tls_out_limit) {
 209                 send_len = data->tls_out_limit - 1;
 210                 flags |= EAP_TLS_FLAGS_MORE_FRAGMENTS;
 211                 if (data->tls_out_pos == 0) {
 212                         flags |= EAP_TLS_FLAGS_LENGTH_INCLUDED;
 213                         send_len -= 4;
 214                 }
 215         }
 216
 217         plen = 1 + send_len;
 218         if (flags & EAP_TLS_FLAGS_LENGTH_INCLUDED)
 219                 plen += 4;
 220
 221         req = eap_tls_msg_alloc(eap_type, plen, EAP_CODE_REQUEST, id);
 222         if (req == NULL)
 223                 return NULL;
 224
 225         wpabuf_put_u8(req, flags); /* Flags */
 226         if (flags & EAP_TLS_FLAGS_LENGTH_INCLUDED)
 227                 wpabuf_put_be32(req, wpabuf_len(data->tls_out));
 228
 229         wpabuf_put_data(req, wpabuf_head_u8(data->tls_out) + data->tls_out_pos,
 230                         send_len);
 231         data->tls_out_pos += send_len;
 232
 233         if (data->tls_out_pos == wpabuf_len(data->tls_out)) {
 234                 wpa_printf(MSG_DEBUG, "SSL: Sending out %lu bytes "
 235                            "(message sent completely)",
 236                            (unsigned long) send_len);
 237                 wpabuf_free(data->tls_out);
 238                 data->tls_out = NULL;
 239                 data->tls_out_pos = 0;
 240                 data->state = MSG;
 241         } else {
 242                 wpa_printf(MSG_DEBUG, "SSL: Sending out %lu bytes "
 243                            "(%lu more to send)", (unsigned long) send_len,
 244                            (unsigned long) wpabuf_len(data->tls_out) -
 245                            data->tls_out_pos);
 246                 data->state = WAIT_FRAG_ACK;
 247         }
 248
 249         return req;
 250 }
 251
 252
 253 struct wpabuf * eap_server_tls_build_ack(u8 id, int eap_type, int version)
 254 {
 255         struct wpabuf *req;
 256
 257         req = eap_tls_msg_alloc(eap_type, 1, EAP_CODE_REQUEST, id);
 258         if (req == NULL)
 259                 return NULL;
 260         wpa_printf(MSG_DEBUG, "SSL: Building ACK");
 261         wpabuf_put_u8(req, version); /* Flags */
 262         return req;
 263 }
 264
 265
 266 static int eap_server_tls_process_cont(struct eap_ssl_data *data,
 267                                        const u8 *buf, size_t len)
 268 {
 269         /* Process continuation of a pending message */
 270         if (len > wpabuf_tailroom(data->tls_in)) {
 271                 wpa_printf(MSG_DEBUG, "SSL: Fragment overflow");
 272                 return -1;
 273         }
 274
 275         wpabuf_put_data(data->tls_in, buf, len);
 276         wpa_printf(MSG_DEBUG, "SSL: Received %lu bytes, waiting for %lu "
 277                    "bytes more", (unsigned long) len,
 278                    (unsigned long) wpabuf_tailroom(data->tls_in));
 279
 280         return 0;
 281 }
 282
 283
 284 static int eap_server_tls_process_fragment(struct eap_ssl_data *data,
 285                                            u8 flags, u32 message_length,
 286                                            const u8 *buf, size_t len)
 287 {
 288         /* Process a fragment that is not the last one of the message */
 289         if (data->tls_in == NULL && !(flags & EAP_TLS_FLAGS_LENGTH_INCLUDED)) {
 290                 wpa_printf(MSG_DEBUG, "SSL: No Message Length field in a "
 291                            "fragmented packet");
 292                 return -1;
 293         }
 294
 295         if (data->tls_in == NULL) {
 296                 /* First fragment of the message */
 297
 298                 /* Limit length to avoid rogue peers from causing large
 299                  * memory allocations. */
 300                 if (message_length > 65536) {
 301                         wpa_printf(MSG_INFO, "SSL: Too long TLS fragment (size"
 302                                    " over 64 kB)");
 303                         return -1;
 304                 }
 305
 306                 if (len > message_length) {
 307                         wpa_printf(MSG_INFO, "SSL: Too much data (%d bytes) in "
 308                                    "first fragment of frame (TLS Message "
 309                                    "Length %d bytes)",
 310                                    (int) len, (int) message_length);
 311                         return -1;
 312                 }
 313
 314                 data->tls_in = wpabuf_alloc(message_length);
 315                 if (data->tls_in == NULL) {
 316                         wpa_printf(MSG_DEBUG, "SSL: No memory for message");
 317                         return -1;
 318                 }
 319                 wpabuf_put_data(data->tls_in, buf, len);
 320                 wpa_printf(MSG_DEBUG, "SSL: Received %lu bytes in first "
 321                            "fragment, waiting for %lu bytes more",
 322                            (unsigned long) len,
 323                            (unsigned long) wpabuf_tailroom(data->tls_in));
 324         }
 325
 326         return 0;
 327 }
 328
 329
 330 int eap_server_tls_phase1(struct eap_sm *sm, struct eap_ssl_data *data)
 331 {
 332         char buf[20];
 333
 334         if (data->tls_out) {
 335                 /* This should not happen.. */
 336                 wpa_printf(MSG_INFO, "SSL: pending tls_out data when "
 337                            "processing new message");
 338                 wpabuf_free(data->tls_out);
 339                 WPA_ASSERT(data->tls_out == NULL);
 340         }
 341
 342         data->tls_out = tls_connection_server_handshake(sm->ssl_ctx,
 343                                                         data->conn,
 344                                                         data->tls_in, NULL);
 345         if (data->tls_out == NULL) {
 346                 wpa_printf(MSG_INFO, "SSL: TLS processing failed");
 347                 return -1;
 348         }
 349         if (tls_connection_get_failed(sm->ssl_ctx, data->conn)) {
 350                 /* TLS processing has failed - return error */
 351                 wpa_printf(MSG_DEBUG, "SSL: Failed - tls_out available to "
 352                            "report error");
 353                 return -1;
 354         }
 355
 356         if (tls_get_version(sm->ssl_ctx, data->conn, buf, sizeof(buf)) == 0) {
 357                 wpa_printf(MSG_DEBUG, "SSL: Using TLS version %s", buf);
 358                 data->tls_v13 = os_strcmp(buf, "TLSv1.3") == 0;
 359         }
 360
 361         if (!sm->serial_num &&
 362             tls_connection_established(sm->ssl_ctx, data->conn))
 363                 sm->serial_num = tls_connection_peer_serial_num(sm->ssl_ctx,
 364                                                                 data->conn);
 365
 366         return 0;
 367 }
 368
 369
 370 static int eap_server_tls_reassemble(struct eap_ssl_data *data, u8 flags,
 371                                      const u8 **pos, size_t *left)
 372 {
 373         unsigned int tls_msg_len = 0;
 374         const u8 *end = *pos + *left;
 375
 376         wpa_hexdump(MSG_MSGDUMP, "SSL: Received data", *pos, *left);
 377
 378         if (flags & EAP_TLS_FLAGS_LENGTH_INCLUDED) {
 379                 if (*left < 4) {
 380                         wpa_printf(MSG_INFO, "SSL: Short frame with TLS "
 381                                    "length");
 382                         return -1;
 383                 }
 384                 tls_msg_len = WPA_GET_BE32(*pos);
 385                 wpa_printf(MSG_DEBUG, "SSL: TLS Message Length: %d",
 386                            tls_msg_len);
 387                 *pos += 4;
 388                 *left -= 4;
 389
 390                 if (*left > tls_msg_len) {
 391                         wpa_printf(MSG_INFO, "SSL: TLS Message Length (%d "
 392                                    "bytes) smaller than this fragment (%d "
 393                                    "bytes)", (int) tls_msg_len, (int) *left);
 394                         return -1;
 395                 }
 396         }
 397
 398         wpa_printf(MSG_DEBUG, "SSL: Received packet: Flags 0x%x "
 399                    "Message Length %u", flags, tls_msg_len);
 400
 401         if (data->state == WAIT_FRAG_ACK) {
 402                 if (*left != 0) {
 403                         wpa_printf(MSG_DEBUG, "SSL: Unexpected payload in "
 404                                    "WAIT_FRAG_ACK state");
 405                         return -1;
 406                 }
 407                 wpa_printf(MSG_DEBUG, "SSL: Fragment acknowledged");
 408                 return 1;
 409         }
 410
 411         if (data->tls_in &&
 412             eap_server_tls_process_cont(data, *pos, end - *pos) < 0)
 413                 return -1;
 414
 415         if (flags & EAP_TLS_FLAGS_MORE_FRAGMENTS) {
 416                 if (eap_server_tls_process_fragment(data, flags, tls_msg_len,
 417                                                     *pos, end - *pos) < 0)
 418                         return -1;
 419
 420                 data->state = FRAG_ACK;
 421                 return 1;
 422         }
 423
 424         if (data->state == FRAG_ACK) {
 425                 wpa_printf(MSG_DEBUG, "SSL: All fragments received");
 426                 data->state = MSG;
 427         }
 428
 429         if (data->tls_in == NULL) {
 430                 /* Wrap unfragmented messages as wpabuf without extra copy */
 431                 wpabuf_set(&data->tmpbuf, *pos, end - *pos);
 432                 data->tls_in = &data->tmpbuf;
 433         }
 434
 435         return 0;
 436 }
 437
 438
 439 static void eap_server_tls_free_in_buf(struct eap_ssl_data *data)
 440 {
 441         if (data->tls_in != &data->tmpbuf)
 442                 wpabuf_free(data->tls_in);
 443         data->tls_in = NULL;
 444 }
 445
 446
 447 struct wpabuf * eap_server_tls_encrypt(struct eap_sm *sm,
 448                                        struct eap_ssl_data *data,
 449                                        const struct wpabuf *plain)
 450 {
 451         struct wpabuf *buf;
 452
 453         buf = tls_connection_encrypt(sm->ssl_ctx, data->conn,
 454                                      plain);
 455         if (buf == NULL) {
 456                 wpa_printf(MSG_INFO, "SSL: Failed to encrypt Phase 2 data");
 457                 return NULL;
 458         }
 459
 460         return buf;
 461 }
 462
 463
 464 int eap_server_tls_process(struct eap_sm *sm, struct eap_ssl_data *data,
 465                            struct wpabuf *respData, void *priv, int eap_type,
 466                            int (*proc_version)(struct eap_sm *sm, void *priv,
 467                                                int peer_version),
 468                            void (*proc_msg)(struct eap_sm *sm, void *priv,
 469                                             const struct wpabuf *respData))
 470 {
 471         const u8 *pos;
 472         u8 flags;
 473         size_t left;
 474         int ret, res = 0;
 475
 476         if (eap_type == EAP_UNAUTH_TLS_TYPE)
 477                 pos = eap_hdr_validate(EAP_VENDOR_UNAUTH_TLS,
 478                                        EAP_VENDOR_TYPE_UNAUTH_TLS, respData,
 479                                        &left);
 480         else if (eap_type == EAP_WFA_UNAUTH_TLS_TYPE)
 481                 pos = eap_hdr_validate(EAP_VENDOR_WFA_NEW,
 482                                        EAP_VENDOR_WFA_UNAUTH_TLS, respData,
 483                                        &left);
 484         else
 485                 pos = eap_hdr_validate(EAP_VENDOR_IETF, eap_type, respData,
 486                                        &left);
 487         if (pos == NULL || left < 1)
 488                 return 0; /* Should not happen - frame already validated */
 489         flags = *pos++;
 490         left--;
 491         wpa_printf(MSG_DEBUG, "SSL: Received packet(len=%lu) - Flags 0x%02x",
 492                    (unsigned long) wpabuf_len(respData), flags);
 493
 494         if (proc_version &&
 495             proc_version(sm, priv, flags & EAP_TLS_VERSION_MASK) < 0)
 496                 return -1;
 497
 498         ret = eap_server_tls_reassemble(data, flags, &pos, &left);
 499         if (ret < 0) {
 500                 res = -1;
 501                 goto done;
 502         } else if (ret == 1)
 503                 return 0;
 504
 505         if (proc_msg)
 506                 proc_msg(sm, priv, respData);
 507
 508         if (tls_connection_get_write_alerts(sm->ssl_ctx, data->conn) > 1) {
 509                 wpa_printf(MSG_INFO, "SSL: Locally detected fatal error in "
 510                            "TLS processing");
 511                 res = -1;
 512         }
 513
 514 done:
 515         eap_server_tls_free_in_buf(data);
 516
 517         return res;
 518 }