lib/socks_gssapi.c

   1 /***************************************************************************
   2  *                                  _   _ ____  _
   3  *  Project                     ___| | | |  _ \| |
   4  *                             / __| | | | |_) | |
   5  *                            | (__| |_| |  _ <| |___
   6  *                             \___|\___/|_| \_\_____|
   7  *
   8  * Copyright (C) 2009, Markus Moeller, <markus_moeller@compuserve.com>
   9  * Copyright (C) 2012 - 2017, Daniel Stenberg, <daniel@haxx.se>, et al.
  10  *
  11  * This software is licensed as described in the file COPYING, which
  12  * you should have received as part of this distribution. The terms
  13  * are also available at https://curl.haxx.se/docs/copyright.html.
  14  *
  15  * You may opt to use, copy, modify, merge, publish, distribute and/or sell
  16  * copies of the Software, and permit persons to whom the Software is
  17  * furnished to do so, under the terms of the COPYING file.
  18  *
  19  * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
  20  * KIND, either express or implied.
  21  *
  22  ***************************************************************************/
  23
  24 #include "curl_setup.h"
  25
  26 #if defined(HAVE_GSSAPI) && !defined(CURL_DISABLE_PROXY)
  27
  28 #include "curl_gssapi.h"
  29 #include "urldata.h"
  30 #include "sendf.h"
  31 #include "connect.h"
  32 #include "timeval.h"
  33 #include "socks.h"
  34 #include "warnless.h"
  35
  36 /* The last 3 #include files should be in this order */
  37 #include "curl_printf.h"
  38 #include "curl_memory.h"
  39 #include "memdebug.h"
  40
  41 static gss_ctx_id_t gss_context = GSS_C_NO_CONTEXT;
  42
  43 /*
  44  * Helper GSS-API error functions.
  45  */
  46 static int check_gss_err(struct Curl_easy *data,
  47                          OM_uint32 major_status,
  48                          OM_uint32 minor_status,
  49                          const char *function)
  50 {
  51   if(GSS_ERROR(major_status)) {
  52     OM_uint32 maj_stat, min_stat;
  53     OM_uint32 msg_ctx = 0;
  54     gss_buffer_desc status_string;
  55     char buf[1024];
  56     size_t len;
  57
  58     len = 0;
  59     msg_ctx = 0;
  60     while(!msg_ctx) {
  61       /* convert major status code (GSS-API error) to text */
  62       maj_stat = gss_display_status(&min_stat, major_status,
  63                                     GSS_C_GSS_CODE,
  64                                     GSS_C_NULL_OID,
  65                                     &msg_ctx, &status_string);
  66       if(maj_stat == GSS_S_COMPLETE) {
  67         if(sizeof(buf) > len + status_string.length + 1) {
  68           strcpy(buf + len, (char *) status_string.value);
  69           len += status_string.length;
  70         }
  71         gss_release_buffer(&min_stat, &status_string);
  72         break;
  73       }
  74       gss_release_buffer(&min_stat, &status_string);
  75     }
  76     if(sizeof(buf) > len + 3) {
  77       strcpy(buf + len, ".\n");
  78       len += 2;
  79     }
  80     msg_ctx = 0;
  81     while(!msg_ctx) {
  82       /* convert minor status code (underlying routine error) to text */
  83       maj_stat = gss_display_status(&min_stat, minor_status,
  84                                     GSS_C_MECH_CODE,
  85                                     GSS_C_NULL_OID,
  86                                     &msg_ctx, &status_string);
  87       if(maj_stat == GSS_S_COMPLETE) {
  88         if(sizeof(buf) > len + status_string.length)
  89           strcpy(buf + len, (char *) status_string.value);
  90         gss_release_buffer(&min_stat, &status_string);
  91         break;
  92       }
  93       gss_release_buffer(&min_stat, &status_string);
  94     }
  95     failf(data, "GSS-API error: %s failed:\n%s", function, buf);
  96     return 1;
  97   }
  98
  99   return 0;
 100 }
 101
 102 CURLcode Curl_SOCKS5_gssapi_negotiate(int sockindex,
 103                                       struct connectdata *conn)
 104 {
 105   struct Curl_easy *data = conn->data;
 106   curl_socket_t sock = conn->sock[sockindex];
 107   CURLcode code;
 108   ssize_t actualread;
 109   ssize_t written;
 110   int result;
 111   OM_uint32 gss_major_status, gss_minor_status, gss_status;
 112   OM_uint32 gss_ret_flags;
 113   int gss_conf_state, gss_enc;
 114   gss_buffer_desc  service = GSS_C_EMPTY_BUFFER;
 115   gss_buffer_desc  gss_send_token = GSS_C_EMPTY_BUFFER;
 116   gss_buffer_desc  gss_recv_token = GSS_C_EMPTY_BUFFER;
 117   gss_buffer_desc  gss_w_token = GSS_C_EMPTY_BUFFER;
 118   gss_buffer_desc* gss_token = GSS_C_NO_BUFFER;
 119   gss_name_t       server = GSS_C_NO_NAME;
 120   gss_name_t       gss_client_name = GSS_C_NO_NAME;
 121   unsigned short   us_length;
 122   char             *user = NULL;
 123   unsigned char socksreq[4]; /* room for GSS-API exchange header only */
 124   const char *serviceptr = data->set.str[STRING_PROXY_SERVICE_NAME] ?
 125                            data->set.str[STRING_PROXY_SERVICE_NAME] : "rcmd";
 126   const size_t serviceptr_length = strlen(serviceptr);
 127
 128   /*   GSS-API request looks like
 129    * +----+------+-----+----------------+
 130    * |VER | MTYP | LEN |     TOKEN      |
 131    * +----+------+----------------------+
 132    * | 1  |  1   |  2  | up to 2^16 - 1 |
 133    * +----+------+-----+----------------+
 134    */
 135
 136   /* prepare service name */
 137   if(strchr(serviceptr, '/')) {
 138     service.length = serviceptr_length;
 139     service.value = malloc(service.length);
 140     if(!service.value)
 141       return CURLE_OUT_OF_MEMORY;
 142     memcpy(service.value, serviceptr, service.length);
 143
 144     gss_major_status = gss_import_name(&gss_minor_status, &service,
 145                                        (gss_OID) GSS_C_NULL_OID, &server);
 146   }
 147   else {
 148     service.value = malloc(serviceptr_length +
 149                            strlen(conn->socks_proxy.host.name) + 2);
 150     if(!service.value)
 151       return CURLE_OUT_OF_MEMORY;
 152     service.length = serviceptr_length +
 153       strlen(conn->socks_proxy.host.name) + 1;
 154     snprintf(service.value, service.length + 1, "%s@%s",
 155              serviceptr, conn->socks_proxy.host.name);
 156
 157     gss_major_status = gss_import_name(&gss_minor_status, &service,
 158                                        GSS_C_NT_HOSTBASED_SERVICE, &server);
 159   }
 160
 161   gss_release_buffer(&gss_status, &service); /* clear allocated memory */
 162
 163   if(check_gss_err(data, gss_major_status,
 164                    gss_minor_status, "gss_import_name()")) {
 165     failf(data, "Failed to create service name.");
 166     gss_release_name(&gss_status, &server);
 167     return CURLE_COULDNT_CONNECT;
 168   }
 169
 170   /* As long as we need to keep sending some context info, and there's no  */
 171   /* errors, keep sending it...                                            */
 172   for(;;) {
 173     gss_major_status = Curl_gss_init_sec_context(data,
 174                                                  &gss_minor_status,
 175                                                  &gss_context,
 176                                                  server,
 177                                                  &Curl_krb5_mech_oid,
 178                                                  NULL,
 179                                                  gss_token,
 180                                                  &gss_send_token,
 181                                                  TRUE,
 182                                                  &gss_ret_flags);
 183
 184     if(gss_token != GSS_C_NO_BUFFER)
 185       gss_release_buffer(&gss_status, &gss_recv_token);
 186     if(check_gss_err(data, gss_major_status,
 187                      gss_minor_status, "gss_init_sec_context")) {
 188       gss_release_name(&gss_status, &server);
 189       gss_release_buffer(&gss_status, &gss_recv_token);
 190       gss_release_buffer(&gss_status, &gss_send_token);
 191       gss_delete_sec_context(&gss_status, &gss_context, NULL);
 192       failf(data, "Failed to initial GSS-API token.");
 193       return CURLE_COULDNT_CONNECT;
 194     }
 195
 196     if(gss_send_token.length != 0) {
 197       socksreq[0] = 1;    /* GSS-API subnegotiation version */
 198       socksreq[1] = 1;    /* authentication message type */
 199       us_length = htons((short)gss_send_token.length);
 200       memcpy(socksreq + 2, &us_length, sizeof(short));
 201
 202       code = Curl_write_plain(conn, sock, (char *)socksreq, 4, &written);
 203       if(code || (4 != written)) {
 204         failf(data, "Failed to send GSS-API authentication request.");
 205         gss_release_name(&gss_status, &server);
 206         gss_release_buffer(&gss_status, &gss_recv_token);
 207         gss_release_buffer(&gss_status, &gss_send_token);
 208         gss_delete_sec_context(&gss_status, &gss_context, NULL);
 209         return CURLE_COULDNT_CONNECT;
 210       }
 211
 212       code = Curl_write_plain(conn, sock, (char *)gss_send_token.value,
 213                               gss_send_token.length, &written);
 214
 215       if(code || ((ssize_t)gss_send_token.length != written)) {
 216         failf(data, "Failed to send GSS-API authentication token.");
 217         gss_release_name(&gss_status, &server);
 218         gss_release_buffer(&gss_status, &gss_recv_token);
 219         gss_release_buffer(&gss_status, &gss_send_token);
 220         gss_delete_sec_context(&gss_status, &gss_context, NULL);
 221         return CURLE_COULDNT_CONNECT;
 222       }
 223
 224     }
 225
 226     gss_release_buffer(&gss_status, &gss_send_token);
 227     gss_release_buffer(&gss_status, &gss_recv_token);
 228     if(gss_major_status != GSS_S_CONTINUE_NEEDED) break;
 229
 230     /* analyse response */
 231
 232     /*   GSS-API response looks like
 233      * +----+------+-----+----------------+
 234      * |VER | MTYP | LEN |     TOKEN      |
 235      * +----+------+----------------------+
 236      * | 1  |  1   |  2  | up to 2^16 - 1 |
 237      * +----+------+-----+----------------+
 238      */
 239
 240     result = Curl_blockread_all(conn, sock, (char *)socksreq, 4, &actualread);
 241     if(result || (actualread != 4)) {
 242       failf(data, "Failed to receive GSS-API authentication response.");
 243       gss_release_name(&gss_status, &server);
 244       gss_delete_sec_context(&gss_status, &gss_context, NULL);
 245       return CURLE_COULDNT_CONNECT;
 246     }
 247
 248     /* ignore the first (VER) byte */
 249     if(socksreq[1] == 255) { /* status / message type */
 250       failf(data, "User was rejected by the SOCKS5 server (%d %d).",
 251             socksreq[0], socksreq[1]);
 252       gss_release_name(&gss_status, &server);
 253       gss_delete_sec_context(&gss_status, &gss_context, NULL);
 254       return CURLE_COULDNT_CONNECT;
 255     }
 256
 257     if(socksreq[1] != 1) { /* status / messgae type */
 258       failf(data, "Invalid GSS-API authentication response type (%d %d).",
 259             socksreq[0], socksreq[1]);
 260       gss_release_name(&gss_status, &server);
 261       gss_delete_sec_context(&gss_status, &gss_context, NULL);
 262       return CURLE_COULDNT_CONNECT;
 263     }
 264
 265     memcpy(&us_length, socksreq + 2, sizeof(short));
 266     us_length = ntohs(us_length);
 267
 268     gss_recv_token.length = us_length;
 269     gss_recv_token.value = malloc(us_length);
 270     if(!gss_recv_token.value) {
 271       failf(data,
 272             "Could not allocate memory for GSS-API authentication "
 273             "response token.");
 274       gss_release_name(&gss_status, &server);
 275       gss_delete_sec_context(&gss_status, &gss_context, NULL);
 276       return CURLE_OUT_OF_MEMORY;
 277     }
 278
 279     result = Curl_blockread_all(conn, sock, (char *)gss_recv_token.value,
 280                                 gss_recv_token.length, &actualread);
 281
 282     if(result || (actualread != us_length)) {
 283       failf(data, "Failed to receive GSS-API authentication token.");
 284       gss_release_name(&gss_status, &server);
 285       gss_release_buffer(&gss_status, &gss_recv_token);
 286       gss_delete_sec_context(&gss_status, &gss_context, NULL);
 287       return CURLE_COULDNT_CONNECT;
 288     }
 289
 290     gss_token = &gss_recv_token;
 291   }
 292
 293   gss_release_name(&gss_status, &server);
 294
 295   /* Everything is good so far, user was authenticated! */
 296   gss_major_status = gss_inquire_context(&gss_minor_status, gss_context,
 297                                          &gss_client_name, NULL, NULL, NULL,
 298                                          NULL, NULL, NULL);
 299   if(check_gss_err(data, gss_major_status,
 300                    gss_minor_status, "gss_inquire_context")) {
 301     gss_delete_sec_context(&gss_status, &gss_context, NULL);
 302     gss_release_name(&gss_status, &gss_client_name);
 303     failf(data, "Failed to determine user name.");
 304     return CURLE_COULDNT_CONNECT;
 305   }
 306   gss_major_status = gss_display_name(&gss_minor_status, gss_client_name,
 307                                       &gss_send_token, NULL);
 308   if(check_gss_err(data, gss_major_status,
 309                    gss_minor_status, "gss_display_name")) {
 310     gss_delete_sec_context(&gss_status, &gss_context, NULL);
 311     gss_release_name(&gss_status, &gss_client_name);
 312     gss_release_buffer(&gss_status, &gss_send_token);
 313     failf(data, "Failed to determine user name.");
 314     return CURLE_COULDNT_CONNECT;
 315   }
 316   user = malloc(gss_send_token.length + 1);
 317   if(!user) {
 318     gss_delete_sec_context(&gss_status, &gss_context, NULL);
 319     gss_release_name(&gss_status, &gss_client_name);
 320     gss_release_buffer(&gss_status, &gss_send_token);
 321     return CURLE_OUT_OF_MEMORY;
 322   }
 323
 324   memcpy(user, gss_send_token.value, gss_send_token.length);
 325   user[gss_send_token.length] = '\0';
 326   gss_release_name(&gss_status, &gss_client_name);
 327   gss_release_buffer(&gss_status, &gss_send_token);
 328   infof(data, "SOCKS5 server authencticated user %s with GSS-API.\n",user);
 329   free(user);
 330   user = NULL;
 331
 332   /* Do encryption */
 333   socksreq[0] = 1;    /* GSS-API subnegotiation version */
 334   socksreq[1] = 2;    /* encryption message type */
 335
 336   gss_enc = 0; /* no data protection */
 337   /* do confidentiality protection if supported */
 338   if(gss_ret_flags & GSS_C_CONF_FLAG)
 339     gss_enc = 2;
 340   /* else do integrity protection */
 341   else if(gss_ret_flags & GSS_C_INTEG_FLAG)
 342     gss_enc = 1;
 343
 344   infof(data, "SOCKS5 server supports GSS-API %s data protection.\n",
 345         (gss_enc == 0)?"no":((gss_enc==1)?"integrity":"confidentiality"));
 346   /* force for the moment to no data protection */
 347   gss_enc = 0;
 348   /*
 349    * Sending the encryption type in clear seems wrong. It should be
 350    * protected with gss_seal()/gss_wrap(). See RFC1961 extract below
 351    * The NEC reference implementations on which this is based is
 352    * therefore at fault
 353    *
 354    *  +------+------+------+.......................+
 355    *  + ver  | mtyp | len  |   token               |
 356    *  +------+------+------+.......................+
 357    *  + 0x01 | 0x02 | 0x02 | up to 2^16 - 1 octets |
 358    *  +------+------+------+.......................+
 359    *
 360    *   Where:
 361    *
 362    *  - "ver" is the protocol version number, here 1 to represent the
 363    *    first version of the SOCKS/GSS-API protocol
 364    *
 365    *  - "mtyp" is the message type, here 2 to represent a protection
 366    *    -level negotiation message
 367    *
 368    *  - "len" is the length of the "token" field in octets
 369    *
 370    *  - "token" is the GSS-API encapsulated protection level
 371    *
 372    * The token is produced by encapsulating an octet containing the
 373    * required protection level using gss_seal()/gss_wrap() with conf_req
 374    * set to FALSE.  The token is verified using gss_unseal()/
 375    * gss_unwrap().
 376    *
 377    */
 378   if(data->set.socks5_gssapi_nec) {
 379     us_length = htons((short)1);
 380     memcpy(socksreq + 2, &us_length, sizeof(short));
 381   }
 382   else {
 383     gss_send_token.length = 1;
 384     gss_send_token.value = malloc(1);
 385     if(!gss_send_token.value) {
 386       gss_delete_sec_context(&gss_status, &gss_context, NULL);
 387       return CURLE_OUT_OF_MEMORY;
 388     }
 389     memcpy(gss_send_token.value, &gss_enc, 1);
 390
 391     gss_major_status = gss_wrap(&gss_minor_status, gss_context, 0,
 392                                 GSS_C_QOP_DEFAULT, &gss_send_token,
 393                                 &gss_conf_state, &gss_w_token);
 394
 395     if(check_gss_err(data, gss_major_status, gss_minor_status, "gss_wrap")) {
 396       gss_release_buffer(&gss_status, &gss_send_token);
 397       gss_release_buffer(&gss_status, &gss_w_token);
 398       gss_delete_sec_context(&gss_status, &gss_context, NULL);
 399       failf(data, "Failed to wrap GSS-API encryption value into token.");
 400       return CURLE_COULDNT_CONNECT;
 401     }
 402     gss_release_buffer(&gss_status, &gss_send_token);
 403
 404     us_length = htons((short)gss_w_token.length);
 405     memcpy(socksreq + 2, &us_length, sizeof(short));
 406   }
 407
 408   code = Curl_write_plain(conn, sock, (char *)socksreq, 4, &written);
 409   if(code  || (4 != written)) {
 410     failf(data, "Failed to send GSS-API encryption request.");
 411     gss_release_buffer(&gss_status, &gss_w_token);
 412     gss_delete_sec_context(&gss_status, &gss_context, NULL);
 413     return CURLE_COULDNT_CONNECT;
 414   }
 415
 416   if(data->set.socks5_gssapi_nec) {
 417     memcpy(socksreq, &gss_enc, 1);
 418     code = Curl_write_plain(conn, sock, socksreq, 1, &written);
 419     if(code || ( 1 != written)) {
 420       failf(data, "Failed to send GSS-API encryption type.");
 421       gss_delete_sec_context(&gss_status, &gss_context, NULL);
 422       return CURLE_COULDNT_CONNECT;
 423     }
 424   }
 425   else {
 426     code = Curl_write_plain(conn, sock, (char *)gss_w_token.value,
 427                             gss_w_token.length, &written);
 428     if(code || ((ssize_t)gss_w_token.length != written)) {
 429       failf(data, "Failed to send GSS-API encryption type.");
 430       gss_release_buffer(&gss_status, &gss_w_token);
 431       gss_delete_sec_context(&gss_status, &gss_context, NULL);
 432       return CURLE_COULDNT_CONNECT;
 433     }
 434     gss_release_buffer(&gss_status, &gss_w_token);
 435   }
 436
 437   result = Curl_blockread_all(conn, sock, (char *)socksreq, 4, &actualread);
 438   if(result || (actualread != 4)) {
 439     failf(data, "Failed to receive GSS-API encryption response.");
 440     gss_delete_sec_context(&gss_status, &gss_context, NULL);
 441     return CURLE_COULDNT_CONNECT;
 442   }
 443
 444   /* ignore the first (VER) byte */
 445   if(socksreq[1] == 255) { /* status / message type */
 446     failf(data, "User was rejected by the SOCKS5 server (%d %d).",
 447           socksreq[0], socksreq[1]);
 448     gss_delete_sec_context(&gss_status, &gss_context, NULL);
 449     return CURLE_COULDNT_CONNECT;
 450   }
 451
 452   if(socksreq[1] != 2) { /* status / messgae type */
 453     failf(data, "Invalid GSS-API encryption response type (%d %d).",
 454           socksreq[0], socksreq[1]);
 455     gss_delete_sec_context(&gss_status, &gss_context, NULL);
 456     return CURLE_COULDNT_CONNECT;
 457   }
 458
 459   memcpy(&us_length, socksreq + 2, sizeof(short));
 460   us_length = ntohs(us_length);
 461
 462   gss_recv_token.length = us_length;
 463   gss_recv_token.value = malloc(gss_recv_token.length);
 464   if(!gss_recv_token.value) {
 465     gss_delete_sec_context(&gss_status, &gss_context, NULL);
 466     return CURLE_OUT_OF_MEMORY;
 467   }
 468   result = Curl_blockread_all(conn, sock, (char *)gss_recv_token.value,
 469                               gss_recv_token.length, &actualread);
 470
 471   if(result || (actualread != us_length)) {
 472     failf(data, "Failed to receive GSS-API encryptrion type.");
 473     gss_release_buffer(&gss_status, &gss_recv_token);
 474     gss_delete_sec_context(&gss_status, &gss_context, NULL);
 475     return CURLE_COULDNT_CONNECT;
 476   }
 477
 478   if(!data->set.socks5_gssapi_nec) {
 479     gss_major_status = gss_unwrap(&gss_minor_status, gss_context,
 480                                   &gss_recv_token, &gss_w_token,
 481                                   0, GSS_C_QOP_DEFAULT);
 482
 483     if(check_gss_err(data, gss_major_status, gss_minor_status, "gss_unwrap")) {
 484       gss_release_buffer(&gss_status, &gss_recv_token);
 485       gss_release_buffer(&gss_status, &gss_w_token);
 486       gss_delete_sec_context(&gss_status, &gss_context, NULL);
 487       failf(data, "Failed to unwrap GSS-API encryption value into token.");
 488       return CURLE_COULDNT_CONNECT;
 489     }
 490     gss_release_buffer(&gss_status, &gss_recv_token);
 491
 492     if(gss_w_token.length != 1) {
 493       failf(data, "Invalid GSS-API encryption response length (%d).",
 494             gss_w_token.length);
 495       gss_release_buffer(&gss_status, &gss_w_token);
 496       gss_delete_sec_context(&gss_status, &gss_context, NULL);
 497       return CURLE_COULDNT_CONNECT;
 498     }
 499
 500     memcpy(socksreq, gss_w_token.value, gss_w_token.length);
 501     gss_release_buffer(&gss_status, &gss_w_token);
 502   }
 503   else {
 504     if(gss_recv_token.length != 1) {
 505       failf(data, "Invalid GSS-API encryption response length (%d).",
 506             gss_recv_token.length);
 507       gss_release_buffer(&gss_status, &gss_recv_token);
 508       gss_delete_sec_context(&gss_status, &gss_context, NULL);
 509       return CURLE_COULDNT_CONNECT;
 510     }
 511
 512     memcpy(socksreq, gss_recv_token.value, gss_recv_token.length);
 513     gss_release_buffer(&gss_status, &gss_recv_token);
 514   }
 515
 516   infof(data, "SOCKS5 access with%s protection granted.\n",
 517         (socksreq[0] == 0)?"out GSS-API data":
 518         ((socksreq[0] == 1)?" GSS-API integrity":" GSS-API confidentiality"));
 519
 520   conn->socks5_gssapi_enctype = socksreq[0];
 521   if(socksreq[0] == 0)
 522     gss_delete_sec_context(&gss_status, &gss_context, NULL);
 523
 524   return CURLE_OK;
 525 }
 526
 527 #endif /* HAVE_GSSAPI && !CURL_DISABLE_PROXY */