libeap/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 = 0;
  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                                char *label, size_t len)
 111 {
 112         u8 *out;
 113
 114         out = os_malloc(len);
 115         if (out == NULL)
 116                 return NULL;
 117
 118         if (tls_connection_prf(sm->ssl_ctx, data->conn, label, 0, 0,
 119                                out, len)) {
 120                 os_free(out);
 121                 return NULL;
 122         }
 123
 124         return out;
 125 }
 126
 127
 128 /**
 129  * eap_server_tls_derive_session_id - Derive a Session-Id based on TLS data
 130  * @sm: Pointer to EAP state machine allocated with eap_peer_sm_init()
 131  * @data: Data for TLS processing
 132  * @eap_type: EAP method used in Phase 1 (EAP_TYPE_TLS/PEAP/TTLS/FAST)
 133  * @len: Pointer to length of the session ID generated
 134  * Returns: Pointer to allocated Session-Id on success or %NULL on failure
 135  *
 136  * This function derive the Session-Id based on the TLS session data
 137  * (client/server random and method type).
 138  *
 139  * The caller is responsible for freeing the returned buffer.
 140  */
 141 u8 * eap_server_tls_derive_session_id(struct eap_sm *sm,
 142                                       struct eap_ssl_data *data, u8 eap_type,
 143                                       size_t *len)
 144 {
 145         struct tls_random keys;
 146         u8 *out;
 147
 148         if (tls_connection_get_random(sm->ssl_ctx, data->conn, &keys))
 149                 return NULL;
 150
 151         if (keys.client_random == NULL || keys.server_random == NULL)
 152                 return NULL;
 153
 154         *len = 1 + keys.client_random_len + keys.server_random_len;
 155         out = os_malloc(*len);
 156         if (out == NULL)
 157                 return NULL;
 158
 159         /* Session-Id = EAP type || client.random || server.random */
 160         out[0] = eap_type;
 161         os_memcpy(out + 1, keys.client_random, keys.client_random_len);
 162         os_memcpy(out + 1 + keys.client_random_len, keys.server_random,
 163                   keys.server_random_len);
 164
 165         return out;
 166 }
 167
 168
 169 struct wpabuf * eap_server_tls_build_msg(struct eap_ssl_data *data,
 170                                          int eap_type, int version, u8 id)
 171 {
 172         struct wpabuf *req;
 173         u8 flags;
 174         size_t send_len, plen;
 175
 176         wpa_printf(MSG_DEBUG, "SSL: Generating Request");
 177         if (data->tls_out == NULL) {
 178                 wpa_printf(MSG_ERROR, "SSL: tls_out NULL in %s", __func__);
 179                 return NULL;
 180         }
 181
 182         flags = version;
 183         send_len = wpabuf_len(data->tls_out) - data->tls_out_pos;
 184         if (1 + send_len > data->tls_out_limit) {
 185                 send_len = data->tls_out_limit - 1;
 186                 flags |= EAP_TLS_FLAGS_MORE_FRAGMENTS;
 187                 if (data->tls_out_pos == 0) {
 188                         flags |= EAP_TLS_FLAGS_LENGTH_INCLUDED;
 189                         send_len -= 4;
 190                 }
 191         }
 192
 193         plen = 1 + send_len;
 194         if (flags & EAP_TLS_FLAGS_LENGTH_INCLUDED)
 195                 plen += 4;
 196
 197         req = eap_tls_msg_alloc(eap_type, plen, EAP_CODE_REQUEST, id);
 198         if (req == NULL)
 199                 return NULL;
 200
 201         wpabuf_put_u8(req, flags); /* Flags */
 202         if (flags & EAP_TLS_FLAGS_LENGTH_INCLUDED)
 203                 wpabuf_put_be32(req, wpabuf_len(data->tls_out));
 204
 205         wpabuf_put_data(req, wpabuf_head_u8(data->tls_out) + data->tls_out_pos,
 206                         send_len);
 207         data->tls_out_pos += send_len;
 208
 209         if (data->tls_out_pos == wpabuf_len(data->tls_out)) {
 210                 wpa_printf(MSG_DEBUG, "SSL: Sending out %lu bytes "
 211                            "(message sent completely)",
 212                            (unsigned long) send_len);
 213                 wpabuf_free(data->tls_out);
 214                 data->tls_out = NULL;
 215                 data->tls_out_pos = 0;
 216                 data->state = MSG;
 217         } else {
 218                 wpa_printf(MSG_DEBUG, "SSL: Sending out %lu bytes "
 219                            "(%lu more to send)", (unsigned long) send_len,
 220                            (unsigned long) wpabuf_len(data->tls_out) -
 221                            data->tls_out_pos);
 222                 data->state = WAIT_FRAG_ACK;
 223         }
 224
 225         return req;
 226 }
 227
 228
 229 struct wpabuf * eap_server_tls_build_ack(u8 id, int eap_type, int version)
 230 {
 231         struct wpabuf *req;
 232
 233         req = eap_tls_msg_alloc(eap_type, 1, EAP_CODE_REQUEST, id);
 234         if (req == NULL)
 235                 return NULL;
 236         wpa_printf(MSG_DEBUG, "SSL: Building ACK");
 237         wpabuf_put_u8(req, version); /* Flags */
 238         return req;
 239 }
 240
 241
 242 static int eap_server_tls_process_cont(struct eap_ssl_data *data,
 243                                        const u8 *buf, size_t len)
 244 {
 245         /* Process continuation of a pending message */
 246         if (len > wpabuf_tailroom(data->tls_in)) {
 247                 wpa_printf(MSG_DEBUG, "SSL: Fragment overflow");
 248                 return -1;
 249         }
 250
 251         wpabuf_put_data(data->tls_in, buf, len);
 252         wpa_printf(MSG_DEBUG, "SSL: Received %lu bytes, waiting for %lu "
 253                    "bytes more", (unsigned long) len,
 254                    (unsigned long) wpabuf_tailroom(data->tls_in));
 255
 256         return 0;
 257 }
 258
 259
 260 static int eap_server_tls_process_fragment(struct eap_ssl_data *data,
 261                                            u8 flags, u32 message_length,
 262                                            const u8 *buf, size_t len)
 263 {
 264         /* Process a fragment that is not the last one of the message */
 265         if (data->tls_in == NULL && !(flags & EAP_TLS_FLAGS_LENGTH_INCLUDED)) {
 266                 wpa_printf(MSG_DEBUG, "SSL: No Message Length field in a "
 267                            "fragmented packet");
 268                 return -1;
 269         }
 270
 271         if (data->tls_in == NULL) {
 272                 /* First fragment of the message */
 273
 274                 /* Limit length to avoid rogue peers from causing large
 275                  * memory allocations. */
 276                 if (message_length > 65536) {
 277                         wpa_printf(MSG_INFO, "SSL: Too long TLS fragment (size"
 278                                    " over 64 kB)");
 279                         return -1;
 280                 }
 281
 282                 if (len > message_length) {
 283                         wpa_printf(MSG_INFO, "SSL: Too much data (%d bytes) in "
 284                                    "first fragment of frame (TLS Message "
 285                                    "Length %d bytes)",
 286                                    (int) len, (int) message_length);
 287                         return -1;
 288                 }
 289
 290                 data->tls_in = wpabuf_alloc(message_length);
 291                 if (data->tls_in == NULL) {
 292                         wpa_printf(MSG_DEBUG, "SSL: No memory for message");
 293                         return -1;
 294                 }
 295                 wpabuf_put_data(data->tls_in, buf, len);
 296                 wpa_printf(MSG_DEBUG, "SSL: Received %lu bytes in first "
 297                            "fragment, waiting for %lu bytes more",
 298                            (unsigned long) len,
 299                            (unsigned long) wpabuf_tailroom(data->tls_in));
 300         }
 301
 302         return 0;
 303 }
 304
 305
 306 int eap_server_tls_phase1(struct eap_sm *sm, struct eap_ssl_data *data)
 307 {
 308         if (data->tls_out) {
 309                 /* This should not happen.. */
 310                 wpa_printf(MSG_INFO, "SSL: pending tls_out data when "
 311                            "processing new message");
 312                 wpabuf_free(data->tls_out);
 313                 WPA_ASSERT(data->tls_out == NULL);
 314         }
 315
 316         data->tls_out = tls_connection_server_handshake(sm->ssl_ctx,
 317                                                         data->conn,
 318                                                         data->tls_in, NULL);
 319         if (data->tls_out == NULL) {
 320                 wpa_printf(MSG_INFO, "SSL: TLS processing failed");
 321                 return -1;
 322         }
 323         if (tls_connection_get_failed(sm->ssl_ctx, data->conn)) {
 324                 /* TLS processing has failed - return error */
 325                 wpa_printf(MSG_DEBUG, "SSL: Failed - tls_out available to "
 326                            "report error");
 327                 return -1;
 328         }
 329
 330         return 0;
 331 }
 332
 333
 334 static int eap_server_tls_reassemble(struct eap_ssl_data *data, u8 flags,
 335                                      const u8 **pos, size_t *left)
 336 {
 337         unsigned int tls_msg_len = 0;
 338         const u8 *end = *pos + *left;
 339
 340         if (flags & EAP_TLS_FLAGS_LENGTH_INCLUDED) {
 341                 if (*left < 4) {
 342                         wpa_printf(MSG_INFO, "SSL: Short frame with TLS "
 343                                    "length");
 344                         return -1;
 345                 }
 346                 tls_msg_len = WPA_GET_BE32(*pos);
 347                 wpa_printf(MSG_DEBUG, "SSL: TLS Message Length: %d",
 348                            tls_msg_len);
 349                 *pos += 4;
 350                 *left -= 4;
 351
 352                 if (*left > tls_msg_len) {
 353                         wpa_printf(MSG_INFO, "SSL: TLS Message Length (%d "
 354                                    "bytes) smaller than this fragment (%d "
 355                                    "bytes)", (int) tls_msg_len, (int) *left);
 356                         return -1;
 357                 }
 358         }
 359
 360         wpa_printf(MSG_DEBUG, "SSL: Received packet: Flags 0x%x "
 361                    "Message Length %u", flags, tls_msg_len);
 362
 363         if (data->state == WAIT_FRAG_ACK) {
 364                 if (*left != 0) {
 365                         wpa_printf(MSG_DEBUG, "SSL: Unexpected payload in "
 366                                    "WAIT_FRAG_ACK state");
 367                         return -1;
 368                 }
 369                 wpa_printf(MSG_DEBUG, "SSL: Fragment acknowledged");
 370                 return 1;
 371         }
 372
 373         if (data->tls_in &&
 374             eap_server_tls_process_cont(data, *pos, end - *pos) < 0)
 375                 return -1;
 376
 377         if (flags & EAP_TLS_FLAGS_MORE_FRAGMENTS) {
 378                 if (eap_server_tls_process_fragment(data, flags, tls_msg_len,
 379                                                     *pos, end - *pos) < 0)
 380                         return -1;
 381
 382                 data->state = FRAG_ACK;
 383                 return 1;
 384         }
 385
 386         if (data->state == FRAG_ACK) {
 387                 wpa_printf(MSG_DEBUG, "SSL: All fragments received");
 388                 data->state = MSG;
 389         }
 390
 391         if (data->tls_in == NULL) {
 392                 /* Wrap unfragmented messages as wpabuf without extra copy */
 393                 wpabuf_set(&data->tmpbuf, *pos, end - *pos);
 394                 data->tls_in = &data->tmpbuf;
 395         }
 396
 397         return 0;
 398 }
 399
 400
 401 static void eap_server_tls_free_in_buf(struct eap_ssl_data *data)
 402 {
 403         if (data->tls_in != &data->tmpbuf)
 404                 wpabuf_free(data->tls_in);
 405         data->tls_in = NULL;
 406 }
 407
 408
 409 struct wpabuf * eap_server_tls_encrypt(struct eap_sm *sm,
 410                                        struct eap_ssl_data *data,
 411                                        const struct wpabuf *plain)
 412 {
 413         struct wpabuf *buf;
 414
 415         buf = tls_connection_encrypt(sm->ssl_ctx, data->conn,
 416                                      plain);
 417         if (buf == NULL) {
 418                 wpa_printf(MSG_INFO, "SSL: Failed to encrypt Phase 2 data");
 419                 return NULL;
 420         }
 421
 422         return buf;
 423 }
 424
 425
 426 int eap_server_tls_process(struct eap_sm *sm, struct eap_ssl_data *data,
 427                            struct wpabuf *respData, void *priv, int eap_type,
 428                            int (*proc_version)(struct eap_sm *sm, void *priv,
 429                                                int peer_version),
 430                            void (*proc_msg)(struct eap_sm *sm, void *priv,
 431                                             const struct wpabuf *respData))
 432 {
 433         const u8 *pos;
 434         u8 flags;
 435         size_t left;
 436         int ret, res = 0;
 437
 438         if (eap_type == EAP_UNAUTH_TLS_TYPE)
 439                 pos = eap_hdr_validate(EAP_VENDOR_UNAUTH_TLS,
 440                                        EAP_VENDOR_TYPE_UNAUTH_TLS, respData,
 441                                        &left);
 442         else if (eap_type == EAP_WFA_UNAUTH_TLS_TYPE)
 443                 pos = eap_hdr_validate(EAP_VENDOR_WFA_NEW,
 444                                        EAP_VENDOR_WFA_UNAUTH_TLS, respData,
 445                                        &left);
 446         else
 447                 pos = eap_hdr_validate(EAP_VENDOR_IETF, eap_type, respData,
 448                                        &left);
 449         if (pos == NULL || left < 1)
 450                 return 0; /* Should not happen - frame already validated */
 451         flags = *pos++;
 452         left--;
 453         wpa_printf(MSG_DEBUG, "SSL: Received packet(len=%lu) - Flags 0x%02x",
 454                    (unsigned long) wpabuf_len(respData), flags);
 455
 456         if (proc_version &&
 457             proc_version(sm, priv, flags & EAP_TLS_VERSION_MASK) < 0)
 458                 return -1;
 459
 460         ret = eap_server_tls_reassemble(data, flags, &pos, &left);
 461         if (ret < 0) {
 462                 res = -1;
 463                 goto done;
 464         } else if (ret == 1)
 465                 return 0;
 466
 467         if (proc_msg)
 468                 proc_msg(sm, priv, respData);
 469
 470         if (tls_connection_get_write_alerts(sm->ssl_ctx, data->conn) > 1) {
 471                 wpa_printf(MSG_INFO, "SSL: Locally detected fatal error in "
 472                            "TLS processing");
 473                 res = -1;
 474         }
 475
 476 done:
 477         eap_server_tls_free_in_buf(data);
 478
 479         return res;
 480 }