lib/socks_gssapi.c

   1 /***************************************************************************
   2  *                                  _   _ ____  _
   3  *  Project                     ___| | | |  _ \| |
   4  *                             / __| | | | |_) | |
   5  *                            | (__| |_| |  _ <| |___
   6  *                             \___|\___/|_| \_\_____|
   7  *
   8  * Copyright (C) 2009, 2011, Markus Moeller, <markus_moeller@compuserve.com>
   9  * Copyright (C) 2012 - 2016, 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 + strlen(conn->socks_proxy.host.name)+1;
 153     snprintf(service.value, service.length+1, "%s@%s",
 154              serviceptr, conn->socks_proxy.host.name);
 155
 156     gss_major_status = gss_import_name(&gss_minor_status, &service,
 157                                        GSS_C_NT_HOSTBASED_SERVICE, &server);
 158   }
 159
 160   gss_release_buffer(&gss_status, &service); /* clear allocated memory */
 161
 162   if(check_gss_err(data, gss_major_status,
 163                    gss_minor_status, "gss_import_name()")) {
 164     failf(data, "Failed to create service name.");
 165     gss_release_name(&gss_status, &server);
 166     return CURLE_COULDNT_CONNECT;
 167   }
 168
 169   /* As long as we need to keep sending some context info, and there's no  */
 170   /* errors, keep sending it...                                            */
 171   for(;;) {
 172     gss_major_status = Curl_gss_init_sec_context(data,
 173                                                  &gss_minor_status,
 174                                                  &gss_context,
 175                                                  server,
 176                                                  &Curl_krb5_mech_oid,
 177                                                  NULL,
 178                                                  gss_token,
 179                                                  &gss_send_token,
 180                                                  TRUE,
 181                                                  &gss_ret_flags);
 182
 183     if(gss_token != GSS_C_NO_BUFFER)
 184       gss_release_buffer(&gss_status, &gss_recv_token);
 185     if(check_gss_err(data, gss_major_status,
 186                      gss_minor_status, "gss_init_sec_context")) {
 187       gss_release_name(&gss_status, &server);
 188       gss_release_buffer(&gss_status, &gss_recv_token);
 189       gss_release_buffer(&gss_status, &gss_send_token);
 190       gss_delete_sec_context(&gss_status, &gss_context, NULL);
 191       failf(data, "Failed to initial GSS-API token.");
 192       return CURLE_COULDNT_CONNECT;
 193     }
 194
 195     if(gss_send_token.length != 0) {
 196       socksreq[0] = 1;    /* GSS-API subnegotiation version */
 197       socksreq[1] = 1;    /* authentication message type */
 198       us_length = htons((short)gss_send_token.length);
 199       memcpy(socksreq+2, &us_length, sizeof(short));
 200
 201       code = Curl_write_plain(conn, sock, (char *)socksreq, 4, &written);
 202       if(code || (4 != written)) {
 203         failf(data, "Failed to send GSS-API authentication request.");
 204         gss_release_name(&gss_status, &server);
 205         gss_release_buffer(&gss_status, &gss_recv_token);
 206         gss_release_buffer(&gss_status, &gss_send_token);
 207         gss_delete_sec_context(&gss_status, &gss_context, NULL);
 208         return CURLE_COULDNT_CONNECT;
 209       }
 210
 211       code = Curl_write_plain(conn, sock, (char *)gss_send_token.value,
 212                               gss_send_token.length, &written);
 213
 214       if(code || ((ssize_t)gss_send_token.length != written)) {
 215         failf(data, "Failed to send GSS-API authentication token.");
 216         gss_release_name(&gss_status, &server);
 217         gss_release_buffer(&gss_status, &gss_recv_token);
 218         gss_release_buffer(&gss_status, &gss_send_token);
 219         gss_delete_sec_context(&gss_status, &gss_context, NULL);
 220         return CURLE_COULDNT_CONNECT;
 221       }
 222
 223     }
 224
 225     gss_release_buffer(&gss_status, &gss_send_token);
 226     gss_release_buffer(&gss_status, &gss_recv_token);
 227     if(gss_major_status != GSS_S_CONTINUE_NEEDED) break;
 228
 229     /* analyse response */
 230
 231     /*   GSS-API response looks like
 232      * +----+------+-----+----------------+
 233      * |VER | MTYP | LEN |     TOKEN      |
 234      * +----+------+----------------------+
 235      * | 1  |  1   |  2  | up to 2^16 - 1 |
 236      * +----+------+-----+----------------+
 237      */
 238
 239     result=Curl_blockread_all(conn, sock, (char *)socksreq, 4, &actualread);
 240     if(result || (actualread != 4)) {
 241       failf(data, "Failed to receive GSS-API authentication response.");
 242       gss_release_name(&gss_status, &server);
 243       gss_delete_sec_context(&gss_status, &gss_context, NULL);
 244       return CURLE_COULDNT_CONNECT;
 245     }
 246
 247     /* ignore the first (VER) byte */
 248     if(socksreq[1] == 255) { /* status / message type */
 249       failf(data, "User was rejected by the SOCKS5 server (%d %d).",
 250             socksreq[0], socksreq[1]);
 251       gss_release_name(&gss_status, &server);
 252       gss_delete_sec_context(&gss_status, &gss_context, NULL);
 253       return CURLE_COULDNT_CONNECT;
 254     }
 255
 256     if(socksreq[1] != 1) { /* status / messgae type */
 257       failf(data, "Invalid GSS-API authentication response type (%d %d).",
 258             socksreq[0], socksreq[1]);
 259       gss_release_name(&gss_status, &server);
 260       gss_delete_sec_context(&gss_status, &gss_context, NULL);
 261       return CURLE_COULDNT_CONNECT;
 262     }
 263
 264     memcpy(&us_length, socksreq+2, sizeof(short));
 265     us_length = ntohs(us_length);
 266
 267     gss_recv_token.length=us_length;
 268     gss_recv_token.value=malloc(us_length);
 269     if(!gss_recv_token.value) {
 270       failf(data,
 271             "Could not allocate memory for GSS-API authentication "
 272             "response token.");
 273       gss_release_name(&gss_status, &server);
 274       gss_delete_sec_context(&gss_status, &gss_context, NULL);
 275       return CURLE_OUT_OF_MEMORY;
 276     }
 277
 278     result=Curl_blockread_all(conn, sock, (char *)gss_recv_token.value,
 279                               gss_recv_token.length, &actualread);
 280
 281     if(result || (actualread != us_length)) {
 282       failf(data, "Failed to receive GSS-API authentication token.");
 283       gss_release_name(&gss_status, &server);
 284       gss_release_buffer(&gss_status, &gss_recv_token);
 285       gss_delete_sec_context(&gss_status, &gss_context, NULL);
 286       return CURLE_COULDNT_CONNECT;
 287     }
 288
 289     gss_token = &gss_recv_token;
 290   }
 291
 292   gss_release_name(&gss_status, &server);
 293
 294   /* Everything is good so far, user was authenticated! */
 295   gss_major_status = gss_inquire_context(&gss_minor_status, gss_context,
 296                                          &gss_client_name, NULL, NULL, NULL,
 297                                          NULL, NULL, NULL);
 298   if(check_gss_err(data, gss_major_status,
 299                    gss_minor_status, "gss_inquire_context")) {
 300     gss_delete_sec_context(&gss_status, &gss_context, NULL);
 301     gss_release_name(&gss_status, &gss_client_name);
 302     failf(data, "Failed to determine user name.");
 303     return CURLE_COULDNT_CONNECT;
 304   }
 305   gss_major_status = gss_display_name(&gss_minor_status, gss_client_name,
 306                                       &gss_send_token, NULL);
 307   if(check_gss_err(data, gss_major_status,
 308                    gss_minor_status, "gss_display_name")) {
 309     gss_delete_sec_context(&gss_status, &gss_context, NULL);
 310     gss_release_name(&gss_status, &gss_client_name);
 311     gss_release_buffer(&gss_status, &gss_send_token);
 312     failf(data, "Failed to determine user name.");
 313     return CURLE_COULDNT_CONNECT;
 314   }
 315   user=malloc(gss_send_token.length+1);
 316   if(!user) {
 317     gss_delete_sec_context(&gss_status, &gss_context, NULL);
 318     gss_release_name(&gss_status, &gss_client_name);
 319     gss_release_buffer(&gss_status, &gss_send_token);
 320     return CURLE_OUT_OF_MEMORY;
 321   }
 322
 323   memcpy(user, gss_send_token.value, gss_send_token.length);
 324   user[gss_send_token.length] = '\0';
 325   gss_release_name(&gss_status, &gss_client_name);
 326   gss_release_buffer(&gss_status, &gss_send_token);
 327   infof(data, "SOCKS5 server authencticated user %s with GSS-API.\n",user);
 328   free(user);
 329   user=NULL;
 330
 331   /* Do encryption */
 332   socksreq[0] = 1;    /* GSS-API subnegotiation version */
 333   socksreq[1] = 2;    /* encryption message type */
 334
 335   gss_enc = 0; /* no data protection */
 336   /* do confidentiality protection if supported */
 337   if(gss_ret_flags & GSS_C_CONF_FLAG)
 338     gss_enc = 2;
 339   /* else do integrity protection */
 340   else if(gss_ret_flags & GSS_C_INTEG_FLAG)
 341     gss_enc = 1;
 342
 343   infof(data, "SOCKS5 server supports GSS-API %s data protection.\n",
 344         (gss_enc==0)?"no":((gss_enc==1)?"integrity":"confidentiality"));
 345   /* force for the moment to no data protection */
 346   gss_enc = 0;
 347   /*
 348    * Sending the encryption type in clear seems wrong. It should be
 349    * protected with gss_seal()/gss_wrap(). See RFC1961 extract below
 350    * The NEC reference implementations on which this is based is
 351    * therefore at fault
 352    *
 353    *  +------+------+------+.......................+
 354    *  + ver  | mtyp | len  |   token               |
 355    *  +------+------+------+.......................+
 356    *  + 0x01 | 0x02 | 0x02 | up to 2^16 - 1 octets |
 357    *  +------+------+------+.......................+
 358    *
 359    *   Where:
 360    *
 361    *  - "ver" is the protocol version number, here 1 to represent the
 362    *    first version of the SOCKS/GSS-API protocol
 363    *
 364    *  - "mtyp" is the message type, here 2 to represent a protection
 365    *    -level negotiation message
 366    *
 367    *  - "len" is the length of the "token" field in octets
 368    *
 369    *  - "token" is the GSS-API encapsulated protection level
 370    *
 371    * The token is produced by encapsulating an octet containing the
 372    * required protection level using gss_seal()/gss_wrap() with conf_req
 373    * set to FALSE.  The token is verified using gss_unseal()/
 374    * gss_unwrap().
 375    *
 376    */
 377   if(data->set.socks5_gssapi_nec) {
 378     us_length = htons((short)1);
 379     memcpy(socksreq+2, &us_length, sizeof(short));
 380   }
 381   else {
 382     gss_send_token.length = 1;
 383     gss_send_token.value = malloc(1);
 384     if(!gss_send_token.value) {
 385       gss_delete_sec_context(&gss_status, &gss_context, NULL);
 386       return CURLE_OUT_OF_MEMORY;
 387     }
 388     memcpy(gss_send_token.value, &gss_enc, 1);
 389
 390     gss_major_status = gss_wrap(&gss_minor_status, gss_context, 0,
 391                                 GSS_C_QOP_DEFAULT, &gss_send_token,
 392                                 &gss_conf_state, &gss_w_token);
 393
 394     if(check_gss_err(data, gss_major_status, gss_minor_status, "gss_wrap")) {
 395       gss_release_buffer(&gss_status, &gss_send_token);
 396       gss_release_buffer(&gss_status, &gss_w_token);
 397       gss_delete_sec_context(&gss_status, &gss_context, NULL);
 398       failf(data, "Failed to wrap GSS-API encryption value into token.");
 399       return CURLE_COULDNT_CONNECT;
 400     }
 401     gss_release_buffer(&gss_status, &gss_send_token);
 402
 403     us_length = htons((short)gss_w_token.length);
 404     memcpy(socksreq+2, &us_length, sizeof(short));
 405   }
 406
 407   code = Curl_write_plain(conn, sock, (char *)socksreq, 4, &written);
 408   if(code  || (4 != written)) {
 409     failf(data, "Failed to send GSS-API encryption request.");
 410     gss_release_buffer(&gss_status, &gss_w_token);
 411     gss_delete_sec_context(&gss_status, &gss_context, NULL);
 412     return CURLE_COULDNT_CONNECT;
 413   }
 414
 415   if(data->set.socks5_gssapi_nec) {
 416     memcpy(socksreq, &gss_enc, 1);
 417     code = Curl_write_plain(conn, sock, socksreq, 1, &written);
 418     if(code || ( 1 != written)) {
 419       failf(data, "Failed to send GSS-API encryption type.");
 420       gss_delete_sec_context(&gss_status, &gss_context, NULL);
 421       return CURLE_COULDNT_CONNECT;
 422     }
 423   }
 424   else {
 425     code = Curl_write_plain(conn, sock, (char *)gss_w_token.value,
 426                             gss_w_token.length, &written);
 427     if(code || ((ssize_t)gss_w_token.length != written)) {
 428       failf(data, "Failed to send GSS-API encryption type.");
 429       gss_release_buffer(&gss_status, &gss_w_token);
 430       gss_delete_sec_context(&gss_status, &gss_context, NULL);
 431       return CURLE_COULDNT_CONNECT;
 432     }
 433     gss_release_buffer(&gss_status, &gss_w_token);
 434   }
 435
 436   result=Curl_blockread_all(conn, sock, (char *)socksreq, 4, &actualread);
 437   if(result || (actualread != 4)) {
 438     failf(data, "Failed to receive GSS-API encryption response.");
 439     gss_delete_sec_context(&gss_status, &gss_context, NULL);
 440     return CURLE_COULDNT_CONNECT;
 441   }
 442
 443   /* ignore the first (VER) byte */
 444   if(socksreq[1] == 255) { /* status / message type */
 445     failf(data, "User was rejected by the SOCKS5 server (%d %d).",
 446           socksreq[0], socksreq[1]);
 447     gss_delete_sec_context(&gss_status, &gss_context, NULL);
 448     return CURLE_COULDNT_CONNECT;
 449   }
 450
 451   if(socksreq[1] != 2) { /* status / messgae type */
 452     failf(data, "Invalid GSS-API encryption response type (%d %d).",
 453           socksreq[0], socksreq[1]);
 454     gss_delete_sec_context(&gss_status, &gss_context, NULL);
 455     return CURLE_COULDNT_CONNECT;
 456   }
 457
 458   memcpy(&us_length, socksreq+2, sizeof(short));
 459   us_length = ntohs(us_length);
 460
 461   gss_recv_token.length= us_length;
 462   gss_recv_token.value=malloc(gss_recv_token.length);
 463   if(!gss_recv_token.value) {
 464     gss_delete_sec_context(&gss_status, &gss_context, NULL);
 465     return CURLE_OUT_OF_MEMORY;
 466   }
 467   result=Curl_blockread_all(conn, sock, (char *)gss_recv_token.value,
 468                             gss_recv_token.length, &actualread);
 469
 470   if(result || (actualread != us_length)) {
 471     failf(data, "Failed to receive GSS-API encryptrion type.");
 472     gss_release_buffer(&gss_status, &gss_recv_token);
 473     gss_delete_sec_context(&gss_status, &gss_context, NULL);
 474     return CURLE_COULDNT_CONNECT;
 475   }
 476
 477   if(!data->set.socks5_gssapi_nec) {
 478     gss_major_status = gss_unwrap(&gss_minor_status, gss_context,
 479                                   &gss_recv_token, &gss_w_token,
 480                                   0, GSS_C_QOP_DEFAULT);
 481
 482     if(check_gss_err(data, gss_major_status, gss_minor_status, "gss_unwrap")) {
 483       gss_release_buffer(&gss_status, &gss_recv_token);
 484       gss_release_buffer(&gss_status, &gss_w_token);
 485       gss_delete_sec_context(&gss_status, &gss_context, NULL);
 486       failf(data, "Failed to unwrap GSS-API encryption value into token.");
 487       return CURLE_COULDNT_CONNECT;
 488     }
 489     gss_release_buffer(&gss_status, &gss_recv_token);
 490
 491     if(gss_w_token.length != 1) {
 492       failf(data, "Invalid GSS-API encryption response length (%d).",
 493             gss_w_token.length);
 494       gss_release_buffer(&gss_status, &gss_w_token);
 495       gss_delete_sec_context(&gss_status, &gss_context, NULL);
 496       return CURLE_COULDNT_CONNECT;
 497     }
 498
 499     memcpy(socksreq, gss_w_token.value, gss_w_token.length);
 500     gss_release_buffer(&gss_status, &gss_w_token);
 501   }
 502   else {
 503     if(gss_recv_token.length != 1) {
 504       failf(data, "Invalid GSS-API encryption response length (%d).",
 505             gss_recv_token.length);
 506       gss_release_buffer(&gss_status, &gss_recv_token);
 507       gss_delete_sec_context(&gss_status, &gss_context, NULL);
 508       return CURLE_COULDNT_CONNECT;
 509     }
 510
 511     memcpy(socksreq, gss_recv_token.value, gss_recv_token.length);
 512     gss_release_buffer(&gss_status, &gss_recv_token);
 513   }
 514
 515   infof(data, "SOCKS5 access with%s protection granted.\n",
 516         (socksreq[0]==0)?"out GSS-API data":
 517         ((socksreq[0]==1)?" GSS-API integrity":" GSS-API confidentiality"));
 518
 519   conn->socks5_gssapi_enctype = socksreq[0];
 520   if(socksreq[0] == 0)
 521     gss_delete_sec_context(&gss_status, &gss_context, NULL);
 522
 523   return CURLE_OK;
 524 }
 525
 526 #endif /* HAVE_GSSAPI && !CURL_DISABLE_PROXY */