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 program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License version 2 as
   7  * published by the Free Software Foundation.
   8  *
   9  * Alternatively, this software may be distributed under the terms of BSD
  10  * license.
  11  *
  12  * See README and COPYING for more details.
  13  */
  14
  15 #include "includes.h"
  16
  17 #include "common.h"
  18 #include "crypto/sha1.h"
  19 #include "crypto/tls.h"
  20 #include "eap_i.h"
  21 #include "eap_tls_common.h"
  22
  23
  24 static void eap_server_tls_free_in_buf(struct eap_ssl_data *data);
  25
  26
  27 int eap_server_tls_ssl_init(struct eap_sm *sm, struct eap_ssl_data *data,
  28                             int verify_peer)
  29 {
  30         data->eap = sm;
  31         data->phase2 = sm->init_phase2;
  32
  33         data->conn = tls_connection_init(sm->ssl_ctx);
  34         if (data->conn == NULL) {
  35                 wpa_printf(MSG_INFO, "SSL: Failed to initialize new TLS "
  36                            "connection");
  37                 return -1;
  38         }
  39
  40         if (tls_connection_set_verify(sm->ssl_ctx, data->conn, verify_peer)) {
  41                 wpa_printf(MSG_INFO, "SSL: Failed to configure verification "
  42                            "of TLS peer certificate");
  43                 tls_connection_deinit(sm->ssl_ctx, data->conn);
  44                 data->conn = NULL;
  45                 return -1;
  46         }
  47
  48         /* TODO: make this configurable */
  49         data->tls_out_limit = 1398;
  50         if (data->phase2) {
  51                 /* Limit the fragment size in the inner TLS authentication
  52                  * since the outer authentication with EAP-PEAP does not yet
  53                  * support fragmentation */
  54                 if (data->tls_out_limit > 100)
  55                         data->tls_out_limit -= 100;
  56         }
  57         return 0;
  58 }
  59
  60
  61 void eap_server_tls_ssl_deinit(struct eap_sm *sm, struct eap_ssl_data *data)
  62 {
  63         tls_connection_deinit(sm->ssl_ctx, data->conn);
  64         eap_server_tls_free_in_buf(data);
  65         wpabuf_free(data->tls_out);
  66         data->tls_out = NULL;
  67 }
  68
  69
  70 u8 * eap_server_tls_derive_key(struct eap_sm *sm, struct eap_ssl_data *data,
  71                                char *label, size_t len)
  72 {
  73         struct tls_keys keys;
  74         u8 *rnd = NULL, *out;
  75
  76         out = os_malloc(len);
  77         if (out == NULL)
  78                 return NULL;
  79
  80         if (tls_connection_prf(sm->ssl_ctx, data->conn, label, 0, out, len) ==
  81             0)
  82                 return out;
  83
  84         if (tls_connection_get_keys(sm->ssl_ctx, data->conn, &keys))
  85                 goto fail;
  86
  87         if (keys.client_random == NULL || keys.server_random == NULL ||
  88             keys.master_key == NULL)
  89                 goto fail;
  90
  91         rnd = os_malloc(keys.client_random_len + keys.server_random_len);
  92         if (rnd == NULL)
  93                 goto fail;
  94         os_memcpy(rnd, keys.client_random, keys.client_random_len);
  95         os_memcpy(rnd + keys.client_random_len, keys.server_random,
  96                   keys.server_random_len);
  97
  98         if (tls_prf(keys.master_key, keys.master_key_len,
  99                     label, rnd, keys.client_random_len +
 100                     keys.server_random_len, out, len))
 101                 goto fail;
 102
 103         os_free(rnd);
 104         return out;
 105
 106 fail:
 107         os_free(out);
 108         os_free(rnd);
 109         return NULL;
 110 }
 111
 112
 113 struct wpabuf * eap_server_tls_build_msg(struct eap_ssl_data *data,
 114                                          int eap_type, int version, u8 id)
 115 {
 116         struct wpabuf *req;
 117         u8 flags;
 118         size_t send_len, plen;
 119
 120         wpa_printf(MSG_DEBUG, "SSL: Generating Request");
 121         if (data->tls_out == NULL) {
 122                 wpa_printf(MSG_ERROR, "SSL: tls_out NULL in %s", __func__);
 123                 return NULL;
 124         }
 125
 126         flags = version;
 127         send_len = wpabuf_len(data->tls_out) - data->tls_out_pos;
 128         if (1 + send_len > data->tls_out_limit) {
 129                 send_len = data->tls_out_limit - 1;
 130                 flags |= EAP_TLS_FLAGS_MORE_FRAGMENTS;
 131                 if (data->tls_out_pos == 0) {
 132                         flags |= EAP_TLS_FLAGS_LENGTH_INCLUDED;
 133                         send_len -= 4;
 134                 }
 135         }
 136
 137         plen = 1 + send_len;
 138         if (flags & EAP_TLS_FLAGS_LENGTH_INCLUDED)
 139                 plen += 4;
 140
 141         req = eap_msg_alloc(EAP_VENDOR_IETF, eap_type, plen,
 142                             EAP_CODE_REQUEST, id);
 143         if (req == NULL)
 144                 return NULL;
 145
 146         wpabuf_put_u8(req, flags); /* Flags */
 147         if (flags & EAP_TLS_FLAGS_LENGTH_INCLUDED)
 148                 wpabuf_put_be32(req, wpabuf_len(data->tls_out));
 149
 150         wpabuf_put_data(req, wpabuf_head_u8(data->tls_out) + data->tls_out_pos,
 151                         send_len);
 152         data->tls_out_pos += send_len;
 153
 154         if (data->tls_out_pos == wpabuf_len(data->tls_out)) {
 155                 wpa_printf(MSG_DEBUG, "SSL: Sending out %lu bytes "
 156                            "(message sent completely)",
 157                            (unsigned long) send_len);
 158                 wpabuf_free(data->tls_out);
 159                 data->tls_out = NULL;
 160                 data->tls_out_pos = 0;
 161                 data->state = MSG;
 162         } else {
 163                 wpa_printf(MSG_DEBUG, "SSL: Sending out %lu bytes "
 164                            "(%lu more to send)", (unsigned long) send_len,
 165                            (unsigned long) wpabuf_len(data->tls_out) -
 166                            data->tls_out_pos);
 167                 data->state = WAIT_FRAG_ACK;
 168         }
 169
 170         return req;
 171 }
 172
 173
 174 struct wpabuf * eap_server_tls_build_ack(u8 id, int eap_type, int version)
 175 {
 176         struct wpabuf *req;
 177
 178         req = eap_msg_alloc(EAP_VENDOR_IETF, eap_type, 1, EAP_CODE_REQUEST,
 179                             id);
 180         if (req == NULL)
 181                 return NULL;
 182         wpa_printf(MSG_DEBUG, "SSL: Building ACK");
 183         wpabuf_put_u8(req, version); /* Flags */
 184         return req;
 185 }
 186
 187
 188 static int eap_server_tls_process_cont(struct eap_ssl_data *data,
 189                                        const u8 *buf, size_t len)
 190 {
 191         /* Process continuation of a pending message */
 192         if (len > wpabuf_tailroom(data->tls_in)) {
 193                 wpa_printf(MSG_DEBUG, "SSL: Fragment overflow");
 194                 return -1;
 195         }
 196
 197         wpabuf_put_data(data->tls_in, buf, len);
 198         wpa_printf(MSG_DEBUG, "SSL: Received %lu bytes, waiting for %lu "
 199                    "bytes more", (unsigned long) len,
 200                    (unsigned long) wpabuf_tailroom(data->tls_in));
 201
 202         return 0;
 203 }
 204
 205
 206 static int eap_server_tls_process_fragment(struct eap_ssl_data *data,
 207                                            u8 flags, u32 message_length,
 208                                            const u8 *buf, size_t len)
 209 {
 210         /* Process a fragment that is not the last one of the message */
 211         if (data->tls_in == NULL && !(flags & EAP_TLS_FLAGS_LENGTH_INCLUDED)) {
 212                 wpa_printf(MSG_DEBUG, "SSL: No Message Length field in a "
 213                            "fragmented packet");
 214                 return -1;
 215         }
 216
 217         if (data->tls_in == NULL) {
 218                 /* First fragment of the message */
 219
 220                 /* Limit length to avoid rogue peers from causing large
 221                  * memory allocations. */
 222                 if (message_length > 65536) {
 223                         wpa_printf(MSG_INFO, "SSL: Too long TLS fragment (size"
 224                                    " over 64 kB)");
 225                         return -1;
 226                 }
 227
 228                 data->tls_in = wpabuf_alloc(message_length);
 229                 if (data->tls_in == NULL) {
 230                         wpa_printf(MSG_DEBUG, "SSL: No memory for message");
 231                         return -1;
 232                 }
 233                 wpabuf_put_data(data->tls_in, buf, len);
 234                 wpa_printf(MSG_DEBUG, "SSL: Received %lu bytes in first "
 235                            "fragment, waiting for %lu bytes more",
 236                            (unsigned long) len,
 237                            (unsigned long) wpabuf_tailroom(data->tls_in));
 238         }
 239
 240         return 0;
 241 }
 242
 243
 244 int eap_server_tls_phase1(struct eap_sm *sm, struct eap_ssl_data *data)
 245 {
 246         if (data->tls_out) {
 247                 /* This should not happen.. */
 248                 wpa_printf(MSG_INFO, "SSL: pending tls_out data when "
 249                            "processing new message");
 250                 wpabuf_free(data->tls_out);
 251                 WPA_ASSERT(data->tls_out == NULL);
 252         }
 253
 254         data->tls_out = tls_connection_server_handshake(sm->ssl_ctx,
 255                                                         data->conn,
 256                                                         data->tls_in, NULL);
 257         if (data->tls_out == NULL) {
 258                 wpa_printf(MSG_INFO, "SSL: TLS processing failed");
 259                 return -1;
 260         }
 261         if (tls_connection_get_failed(sm->ssl_ctx, data->conn)) {
 262                 /* TLS processing has failed - return error */
 263                 wpa_printf(MSG_DEBUG, "SSL: Failed - tls_out available to "
 264                            "report error");
 265                 return -1;
 266         }
 267
 268         return 0;
 269 }
 270
 271
 272 static int eap_server_tls_reassemble(struct eap_ssl_data *data, u8 flags,
 273                                      const u8 **pos, size_t *left)
 274 {
 275         unsigned int tls_msg_len = 0;
 276         const u8 *end = *pos + *left;
 277
 278         if (flags & EAP_TLS_FLAGS_LENGTH_INCLUDED) {
 279                 if (*left < 4) {
 280                         wpa_printf(MSG_INFO, "SSL: Short frame with TLS "
 281                                    "length");
 282                         return -1;
 283                 }
 284                 tls_msg_len = WPA_GET_BE32(*pos);
 285                 wpa_printf(MSG_DEBUG, "SSL: TLS Message Length: %d",
 286                            tls_msg_len);
 287                 *pos += 4;
 288                 *left -= 4;
 289         }
 290
 291         wpa_printf(MSG_DEBUG, "SSL: Received packet: Flags 0x%x "
 292                    "Message Length %u", flags, tls_msg_len);
 293
 294         if (data->state == WAIT_FRAG_ACK) {
 295                 if (*left != 0) {
 296                         wpa_printf(MSG_DEBUG, "SSL: Unexpected payload in "
 297                                    "WAIT_FRAG_ACK state");
 298                         return -1;
 299                 }
 300                 wpa_printf(MSG_DEBUG, "SSL: Fragment acknowledged");
 301                 return 1;
 302         }
 303
 304         if (data->tls_in &&
 305             eap_server_tls_process_cont(data, *pos, end - *pos) < 0)
 306                 return -1;
 307
 308         if (flags & EAP_TLS_FLAGS_MORE_FRAGMENTS) {
 309                 if (eap_server_tls_process_fragment(data, flags, tls_msg_len,
 310                                                     *pos, end - *pos) < 0)
 311                         return -1;
 312
 313                 data->state = FRAG_ACK;
 314                 return 1;
 315         }
 316
 317         if (data->state == FRAG_ACK) {
 318                 wpa_printf(MSG_DEBUG, "SSL: All fragments received");
 319                 data->state = MSG;
 320         }
 321
 322         if (data->tls_in == NULL) {
 323                 /* Wrap unfragmented messages as wpabuf without extra copy */
 324                 wpabuf_set(&data->tmpbuf, *pos, end - *pos);
 325                 data->tls_in = &data->tmpbuf;
 326         }
 327
 328         return 0;
 329 }
 330
 331
 332 static void eap_server_tls_free_in_buf(struct eap_ssl_data *data)
 333 {
 334         if (data->tls_in != &data->tmpbuf)
 335                 wpabuf_free(data->tls_in);
 336         data->tls_in = NULL;
 337 }
 338
 339
 340 struct wpabuf * eap_server_tls_encrypt(struct eap_sm *sm,
 341                                        struct eap_ssl_data *data,
 342                                        const struct wpabuf *plain)
 343 {
 344         struct wpabuf *buf;
 345
 346         buf = tls_connection_encrypt(sm->ssl_ctx, data->conn,
 347                                      plain);
 348         if (buf == NULL) {
 349                 wpa_printf(MSG_INFO, "SSL: Failed to encrypt Phase 2 data");
 350                 return NULL;
 351         }
 352
 353         return buf;
 354 }
 355
 356
 357 int eap_server_tls_process(struct eap_sm *sm, struct eap_ssl_data *data,
 358                            struct wpabuf *respData, void *priv, int eap_type,
 359                            int (*proc_version)(struct eap_sm *sm, void *priv,
 360                                                int peer_version),
 361                            void (*proc_msg)(struct eap_sm *sm, void *priv,
 362                                             const struct wpabuf *respData))
 363 {
 364         const u8 *pos;
 365         u8 flags;
 366         size_t left;
 367         int ret, res = 0;
 368
 369         pos = eap_hdr_validate(EAP_VENDOR_IETF, eap_type, respData, &left);
 370         if (pos == NULL || left < 1)
 371                 return 0; /* Should not happen - frame already validated */
 372         flags = *pos++;
 373         left--;
 374         wpa_printf(MSG_DEBUG, "SSL: Received packet(len=%lu) - Flags 0x%02x",
 375                    (unsigned long) wpabuf_len(respData), flags);
 376
 377         if (proc_version &&
 378             proc_version(sm, priv, flags & EAP_TLS_VERSION_MASK) < 0)
 379                 return -1;
 380
 381         ret = eap_server_tls_reassemble(data, flags, &pos, &left);
 382         if (ret < 0) {
 383                 res = -1;
 384                 goto done;
 385         } else if (ret == 1)
 386                 return 0;
 387
 388         if (proc_msg)
 389                 proc_msg(sm, priv, respData);
 390
 391         if (tls_connection_get_write_alerts(sm->ssl_ctx, data->conn) > 1) {
 392                 wpa_printf(MSG_INFO, "SSL: Locally detected fatal error in "
 393                            "TLS processing");
 394                 res = -1;
 395         }
 396
 397 done:
 398         eap_server_tls_free_in_buf(data);
 399
 400         return res;
 401 }