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
 127   /*   GSS-API request looks like
 128    * +----+------+-----+----------------+
 129    * |VER | MTYP | LEN |     TOKEN      |
 130    * +----+------+----------------------+
 131    * | 1  |  1   |  2  | up to 2^16 - 1 |
 132    * +----+------+-----+----------------+
 133    */
 134
 135   /* prepare service name */
 136   if(strchr(serviceptr, '/')) {
 137     service.value = malloc(strlen(serviceptr));
 138     if(!service.value)
 139       return CURLE_OUT_OF_MEMORY;
 140     service.length = strlen(serviceptr);
 141     memcpy(service.value, serviceptr, service.length);
 142
 143     gss_major_status = gss_import_name(&gss_minor_status, &service,
 144                                        (gss_OID) GSS_C_NULL_OID, &server);
 145   }
 146   else {
 147     service.value = malloc(strlen(serviceptr) +strlen(conn->proxy.name)+2);
 148     if(!service.value)
 149       return CURLE_OUT_OF_MEMORY;
 150     service.length = strlen(serviceptr) +strlen(conn->proxy.name)+1;
 151     snprintf(service.value, service.length+1, "%s@%s",
 152              serviceptr, conn->proxy.name);
 153
 154     gss_major_status = gss_import_name(&gss_minor_status, &service,
 155                                        GSS_C_NT_HOSTBASED_SERVICE, &server);
 156   }
 157
 158   gss_release_buffer(&gss_status, &service); /* clear allocated memory */
 159
 160   if(check_gss_err(data, gss_major_status,
 161                    gss_minor_status, "gss_import_name()")) {
 162     failf(data, "Failed to create service name.");
 163     gss_release_name(&gss_status, &server);
 164     return CURLE_COULDNT_CONNECT;
 165   }
 166
 167   /* As long as we need to keep sending some context info, and there's no  */
 168   /* errors, keep sending it...                                            */
 169   for(;;) {
 170     gss_major_status = Curl_gss_init_sec_context(data,
 171                                                  &gss_minor_status,
 172                                                  &gss_context,
 173                                                  server,
 174                                                  &Curl_krb5_mech_oid,
 175                                                  NULL,
 176                                                  gss_token,
 177                                                  &gss_send_token,
 178                                                  TRUE,
 179                                                  &gss_ret_flags);
 180
 181     if(gss_token != GSS_C_NO_BUFFER)
 182       gss_release_buffer(&gss_status, &gss_recv_token);
 183     if(check_gss_err(data, gss_major_status,
 184                      gss_minor_status, "gss_init_sec_context")) {
 185       gss_release_name(&gss_status, &server);
 186       gss_release_buffer(&gss_status, &gss_recv_token);
 187       gss_release_buffer(&gss_status, &gss_send_token);
 188       gss_delete_sec_context(&gss_status, &gss_context, NULL);
 189       failf(data, "Failed to initial GSS-API token.");
 190       return CURLE_COULDNT_CONNECT;
 191     }
 192
 193     if(gss_send_token.length != 0) {
 194       socksreq[0] = 1;    /* GSS-API subnegotiation version */
 195       socksreq[1] = 1;    /* authentication message type */
 196       us_length = htons((short)gss_send_token.length);
 197       memcpy(socksreq+2, &us_length, sizeof(short));
 198
 199       code = Curl_write_plain(conn, sock, (char *)socksreq, 4, &written);
 200       if(code || (4 != written)) {
 201         failf(data, "Failed to send GSS-API authentication request.");
 202         gss_release_name(&gss_status, &server);
 203         gss_release_buffer(&gss_status, &gss_recv_token);
 204         gss_release_buffer(&gss_status, &gss_send_token);
 205         gss_delete_sec_context(&gss_status, &gss_context, NULL);
 206         return CURLE_COULDNT_CONNECT;
 207       }
 208
 209       code = Curl_write_plain(conn, sock, (char *)gss_send_token.value,
 210                               gss_send_token.length, &written);
 211
 212       if(code || ((ssize_t)gss_send_token.length != written)) {
 213         failf(data, "Failed to send GSS-API authentication token.");
 214         gss_release_name(&gss_status, &server);
 215         gss_release_buffer(&gss_status, &gss_recv_token);
 216         gss_release_buffer(&gss_status, &gss_send_token);
 217         gss_delete_sec_context(&gss_status, &gss_context, NULL);
 218         return CURLE_COULDNT_CONNECT;
 219       }
 220
 221     }
 222
 223     gss_release_buffer(&gss_status, &gss_send_token);
 224     gss_release_buffer(&gss_status, &gss_recv_token);
 225     if(gss_major_status != GSS_S_CONTINUE_NEEDED) break;
 226
 227     /* analyse response */
 228
 229     /*   GSS-API response looks like
 230      * +----+------+-----+----------------+
 231      * |VER | MTYP | LEN |     TOKEN      |
 232      * +----+------+----------------------+
 233      * | 1  |  1   |  2  | up to 2^16 - 1 |
 234      * +----+------+-----+----------------+
 235      */
 236
 237     result=Curl_blockread_all(conn, sock, (char *)socksreq, 4, &actualread);
 238     if(result || (actualread != 4)) {
 239       failf(data, "Failed to receive GSS-API authentication response.");
 240       gss_release_name(&gss_status, &server);
 241       gss_delete_sec_context(&gss_status, &gss_context, NULL);
 242       return CURLE_COULDNT_CONNECT;
 243     }
 244
 245     /* ignore the first (VER) byte */
 246     if(socksreq[1] == 255) { /* status / message type */
 247       failf(data, "User was rejected by the SOCKS5 server (%d %d).",
 248             socksreq[0], socksreq[1]);
 249       gss_release_name(&gss_status, &server);
 250       gss_delete_sec_context(&gss_status, &gss_context, NULL);
 251       return CURLE_COULDNT_CONNECT;
 252     }
 253
 254     if(socksreq[1] != 1) { /* status / messgae type */
 255       failf(data, "Invalid GSS-API authentication response type (%d %d).",
 256             socksreq[0], socksreq[1]);
 257       gss_release_name(&gss_status, &server);
 258       gss_delete_sec_context(&gss_status, &gss_context, NULL);
 259       return CURLE_COULDNT_CONNECT;
 260     }
 261
 262     memcpy(&us_length, socksreq+2, sizeof(short));
 263     us_length = ntohs(us_length);
 264
 265     gss_recv_token.length=us_length;
 266     gss_recv_token.value=malloc(us_length);
 267     if(!gss_recv_token.value) {
 268       failf(data,
 269             "Could not allocate memory for GSS-API authentication "
 270             "response token.");
 271       gss_release_name(&gss_status, &server);
 272       gss_delete_sec_context(&gss_status, &gss_context, NULL);
 273       return CURLE_OUT_OF_MEMORY;
 274     }
 275
 276     result=Curl_blockread_all(conn, sock, (char *)gss_recv_token.value,
 277                               gss_recv_token.length, &actualread);
 278
 279     if(result || (actualread != us_length)) {
 280       failf(data, "Failed to receive GSS-API authentication token.");
 281       gss_release_name(&gss_status, &server);
 282       gss_release_buffer(&gss_status, &gss_recv_token);
 283       gss_delete_sec_context(&gss_status, &gss_context, NULL);
 284       return CURLE_COULDNT_CONNECT;
 285     }
 286
 287     gss_token = &gss_recv_token;
 288   }
 289
 290   gss_release_name(&gss_status, &server);
 291
 292   /* Everything is good so far, user was authenticated! */
 293   gss_major_status = gss_inquire_context (&gss_minor_status, gss_context,
 294                                           &gss_client_name, NULL, NULL, NULL,
 295                                           NULL, NULL, NULL);
 296   if(check_gss_err(data, gss_major_status,
 297                    gss_minor_status, "gss_inquire_context")) {
 298     gss_delete_sec_context(&gss_status, &gss_context, NULL);
 299     gss_release_name(&gss_status, &gss_client_name);
 300     failf(data, "Failed to determine user name.");
 301     return CURLE_COULDNT_CONNECT;
 302   }
 303   gss_major_status = gss_display_name(&gss_minor_status, gss_client_name,
 304                                       &gss_send_token, NULL);
 305   if(check_gss_err(data, gss_major_status,
 306                    gss_minor_status, "gss_display_name")) {
 307     gss_delete_sec_context(&gss_status, &gss_context, NULL);
 308     gss_release_name(&gss_status, &gss_client_name);
 309     gss_release_buffer(&gss_status, &gss_send_token);
 310     failf(data, "Failed to determine user name.");
 311     return CURLE_COULDNT_CONNECT;
 312   }
 313   user=malloc(gss_send_token.length+1);
 314   if(!user) {
 315     gss_delete_sec_context(&gss_status, &gss_context, NULL);
 316     gss_release_name(&gss_status, &gss_client_name);
 317     gss_release_buffer(&gss_status, &gss_send_token);
 318     return CURLE_OUT_OF_MEMORY;
 319   }
 320
 321   memcpy(user, gss_send_token.value, gss_send_token.length);
 322   user[gss_send_token.length] = '\0';
 323   gss_release_name(&gss_status, &gss_client_name);
 324   gss_release_buffer(&gss_status, &gss_send_token);
 325   infof(data, "SOCKS5 server authencticated user %s with GSS-API.\n",user);
 326   free(user);
 327   user=NULL;
 328
 329   /* Do encryption */
 330   socksreq[0] = 1;    /* GSS-API subnegotiation version */
 331   socksreq[1] = 2;    /* encryption message type */
 332
 333   gss_enc = 0; /* no data protection */
 334   /* do confidentiality protection if supported */
 335   if(gss_ret_flags & GSS_C_CONF_FLAG)
 336     gss_enc = 2;
 337   /* else do integrity protection */
 338   else if(gss_ret_flags & GSS_C_INTEG_FLAG)
 339     gss_enc = 1;
 340
 341   infof(data, "SOCKS5 server supports GSS-API %s data protection.\n",
 342         (gss_enc==0)?"no":((gss_enc==1)?"integrity":"confidentiality"));
 343   /* force for the moment to no data protection */
 344   gss_enc = 0;
 345   /*
 346    * Sending the encryption type in clear seems wrong. It should be
 347    * protected with gss_seal()/gss_wrap(). See RFC1961 extract below
 348    * The NEC reference implementations on which this is based is
 349    * therefore at fault
 350    *
 351    *  +------+------+------+.......................+
 352    *  + ver  | mtyp | len  |   token               |
 353    *  +------+------+------+.......................+
 354    *  + 0x01 | 0x02 | 0x02 | up to 2^16 - 1 octets |
 355    *  +------+------+------+.......................+
 356    *
 357    *   Where:
 358    *
 359    *  - "ver" is the protocol version number, here 1 to represent the
 360    *    first version of the SOCKS/GSS-API protocol
 361    *
 362    *  - "mtyp" is the message type, here 2 to represent a protection
 363    *    -level negotiation message
 364    *
 365    *  - "len" is the length of the "token" field in octets
 366    *
 367    *  - "token" is the GSS-API encapsulated protection level
 368    *
 369    * The token is produced by encapsulating an octet containing the
 370    * required protection level using gss_seal()/gss_wrap() with conf_req
 371    * set to FALSE.  The token is verified using gss_unseal()/
 372    * gss_unwrap().
 373    *
 374    */
 375   if(data->set.socks5_gssapi_nec) {
 376     us_length = htons((short)1);
 377     memcpy(socksreq+2, &us_length, sizeof(short));
 378   }
 379   else {
 380     gss_send_token.length = 1;
 381     gss_send_token.value = malloc(1);
 382     if(!gss_send_token.value) {
 383       gss_delete_sec_context(&gss_status, &gss_context, NULL);
 384       return CURLE_OUT_OF_MEMORY;
 385     }
 386     memcpy(gss_send_token.value, &gss_enc, 1);
 387
 388     gss_major_status = gss_wrap(&gss_minor_status, gss_context, 0,
 389                                 GSS_C_QOP_DEFAULT, &gss_send_token,
 390                                 &gss_conf_state, &gss_w_token);
 391
 392     if(check_gss_err(data, gss_major_status, gss_minor_status, "gss_wrap")) {
 393       gss_release_buffer(&gss_status, &gss_send_token);
 394       gss_release_buffer(&gss_status, &gss_w_token);
 395       gss_delete_sec_context(&gss_status, &gss_context, NULL);
 396       failf(data, "Failed to wrap GSS-API encryption value into token.");
 397       return CURLE_COULDNT_CONNECT;
 398     }
 399     gss_release_buffer(&gss_status, &gss_send_token);
 400
 401     us_length = htons((short)gss_w_token.length);
 402     memcpy(socksreq+2, &us_length, sizeof(short));
 403   }
 404
 405   code = Curl_write_plain(conn, sock, (char *)socksreq, 4, &written);
 406   if(code  || (4 != written)) {
 407     failf(data, "Failed to send GSS-API encryption request.");
 408     gss_release_buffer(&gss_status, &gss_w_token);
 409     gss_delete_sec_context(&gss_status, &gss_context, NULL);
 410     return CURLE_COULDNT_CONNECT;
 411   }
 412
 413   if(data->set.socks5_gssapi_nec) {
 414     memcpy(socksreq, &gss_enc, 1);
 415     code = Curl_write_plain(conn, sock, socksreq, 1, &written);
 416     if(code || ( 1 != written)) {
 417       failf(data, "Failed to send GSS-API encryption type.");
 418       gss_delete_sec_context(&gss_status, &gss_context, NULL);
 419       return CURLE_COULDNT_CONNECT;
 420     }
 421   }
 422   else {
 423     code = Curl_write_plain(conn, sock, (char *)gss_w_token.value,
 424                             gss_w_token.length, &written);
 425     if(code || ((ssize_t)gss_w_token.length != written)) {
 426       failf(data, "Failed to send GSS-API encryption type.");
 427       gss_release_buffer(&gss_status, &gss_w_token);
 428       gss_delete_sec_context(&gss_status, &gss_context, NULL);
 429       return CURLE_COULDNT_CONNECT;
 430     }
 431     gss_release_buffer(&gss_status, &gss_w_token);
 432   }
 433
 434   result=Curl_blockread_all(conn, sock, (char *)socksreq, 4, &actualread);
 435   if(result || (actualread != 4)) {
 436     failf(data, "Failed to receive GSS-API encryption response.");
 437     gss_delete_sec_context(&gss_status, &gss_context, NULL);
 438     return CURLE_COULDNT_CONNECT;
 439   }
 440
 441   /* ignore the first (VER) byte */
 442   if(socksreq[1] == 255) { /* status / message type */
 443     failf(data, "User was rejected by the SOCKS5 server (%d %d).",
 444           socksreq[0], socksreq[1]);
 445     gss_delete_sec_context(&gss_status, &gss_context, NULL);
 446     return CURLE_COULDNT_CONNECT;
 447   }
 448
 449   if(socksreq[1] != 2) { /* status / messgae type */
 450     failf(data, "Invalid GSS-API encryption response type (%d %d).",
 451           socksreq[0], socksreq[1]);
 452     gss_delete_sec_context(&gss_status, &gss_context, NULL);
 453     return CURLE_COULDNT_CONNECT;
 454   }
 455
 456   memcpy(&us_length, socksreq+2, sizeof(short));
 457   us_length = ntohs(us_length);
 458
 459   gss_recv_token.length= us_length;
 460   gss_recv_token.value=malloc(gss_recv_token.length);
 461   if(!gss_recv_token.value) {
 462     gss_delete_sec_context(&gss_status, &gss_context, NULL);
 463     return CURLE_OUT_OF_MEMORY;
 464   }
 465   result=Curl_blockread_all(conn, sock, (char *)gss_recv_token.value,
 466                             gss_recv_token.length, &actualread);
 467
 468   if(result || (actualread != us_length)) {
 469     failf(data, "Failed to receive GSS-API encryptrion type.");
 470     gss_release_buffer(&gss_status, &gss_recv_token);
 471     gss_delete_sec_context(&gss_status, &gss_context, NULL);
 472     return CURLE_COULDNT_CONNECT;
 473   }
 474
 475   if(!data->set.socks5_gssapi_nec) {
 476     gss_major_status = gss_unwrap(&gss_minor_status, gss_context,
 477                                   &gss_recv_token, &gss_w_token,
 478                                   0, GSS_C_QOP_DEFAULT);
 479
 480     if(check_gss_err(data, gss_major_status, gss_minor_status, "gss_unwrap")) {
 481       gss_release_buffer(&gss_status, &gss_recv_token);
 482       gss_release_buffer(&gss_status, &gss_w_token);
 483       gss_delete_sec_context(&gss_status, &gss_context, NULL);
 484       failf(data, "Failed to unwrap GSS-API encryption value into token.");
 485       return CURLE_COULDNT_CONNECT;
 486     }
 487     gss_release_buffer(&gss_status, &gss_recv_token);
 488
 489     if(gss_w_token.length != 1) {
 490       failf(data, "Invalid GSS-API encryption response length (%d).",
 491             gss_w_token.length);
 492       gss_release_buffer(&gss_status, &gss_w_token);
 493       gss_delete_sec_context(&gss_status, &gss_context, NULL);
 494       return CURLE_COULDNT_CONNECT;
 495     }
 496
 497     memcpy(socksreq, gss_w_token.value, gss_w_token.length);
 498     gss_release_buffer(&gss_status, &gss_w_token);
 499   }
 500   else {
 501     if(gss_recv_token.length != 1) {
 502       failf(data, "Invalid GSS-API encryption response length (%d).",
 503             gss_recv_token.length);
 504       gss_release_buffer(&gss_status, &gss_recv_token);
 505       gss_delete_sec_context(&gss_status, &gss_context, NULL);
 506       return CURLE_COULDNT_CONNECT;
 507     }
 508
 509     memcpy(socksreq, gss_recv_token.value, gss_recv_token.length);
 510     gss_release_buffer(&gss_status, &gss_recv_token);
 511   }
 512
 513   infof(data, "SOCKS5 access with%s protection granted.\n",
 514         (socksreq[0]==0)?"out GSS-API data":
 515         ((socksreq[0]==1)?" GSS-API integrity":" GSS-API confidentiality"));
 516
 517   conn->socks5_gssapi_enctype = socksreq[0];
 518   if(socksreq[0] == 0)
 519     gss_delete_sec_context(&gss_status, &gss_context, NULL);
 520
 521   return CURLE_OK;
 522 }
 523
 524 #endif /* HAVE_GSSAPI && !CURL_DISABLE_PROXY */