Utilities/cmcurl/lib/socks_gssapi.c

   1 /***************************************************************************
   2  *                                  _   _ ____  _
   3  *  Project                     ___| | | |  _ \| |
   4  *                             / __| | | | |_) | |
   5  *                            | (__| |_| |  _ <| |___
   6  *                             \___|\___/|_| \_\_____|
   7  *
   8  * Copyright (C) 2012 - 2021, Daniel Stenberg, <daniel@haxx.se>, et al.
   9  * Copyright (C) 2009, Markus Moeller, <markus_moeller@compuserve.com>
  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.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: %s", function, buf);
  96     return 1;
  97   }
  98
  99   return 0;
 100 }
 101
 102 CURLcode Curl_SOCKS5_gssapi_negotiate(int sockindex,
 103                                       struct Curl_easy *data)
 104 {
 105   struct connectdata *conn = data->conn;
 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     msnprintf(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   (void)curlx_nonblock(sock, FALSE);
 171
 172   /* As long as we need to keep sending some context info, and there's no  */
 173   /* errors, keep sending it...                                            */
 174   for(;;) {
 175     gss_major_status = Curl_gss_init_sec_context(data,
 176                                                  &gss_minor_status,
 177                                                  &gss_context,
 178                                                  server,
 179                                                  &Curl_krb5_mech_oid,
 180                                                  NULL,
 181                                                  gss_token,
 182                                                  &gss_send_token,
 183                                                  TRUE,
 184                                                  &gss_ret_flags);
 185
 186     if(gss_token != GSS_C_NO_BUFFER)
 187       gss_release_buffer(&gss_status, &gss_recv_token);
 188     if(check_gss_err(data, gss_major_status,
 189                      gss_minor_status, "gss_init_sec_context")) {
 190       gss_release_name(&gss_status, &server);
 191       gss_release_buffer(&gss_status, &gss_recv_token);
 192       gss_release_buffer(&gss_status, &gss_send_token);
 193       gss_delete_sec_context(&gss_status, &gss_context, NULL);
 194       failf(data, "Failed to initial GSS-API token.");
 195       return CURLE_COULDNT_CONNECT;
 196     }
 197
 198     if(gss_send_token.length) {
 199       socksreq[0] = 1;    /* GSS-API subnegotiation version */
 200       socksreq[1] = 1;    /* authentication message type */
 201       us_length = htons((short)gss_send_token.length);
 202       memcpy(socksreq + 2, &us_length, sizeof(short));
 203
 204       code = Curl_write_plain(data, sock, (char *)socksreq, 4, &written);
 205       if(code || (4 != written)) {
 206         failf(data, "Failed to send GSS-API authentication request.");
 207         gss_release_name(&gss_status, &server);
 208         gss_release_buffer(&gss_status, &gss_recv_token);
 209         gss_release_buffer(&gss_status, &gss_send_token);
 210         gss_delete_sec_context(&gss_status, &gss_context, NULL);
 211         return CURLE_COULDNT_CONNECT;
 212       }
 213
 214       code = Curl_write_plain(data, sock, (char *)gss_send_token.value,
 215                               gss_send_token.length, &written);
 216
 217       if(code || ((ssize_t)gss_send_token.length != written)) {
 218         failf(data, "Failed to send GSS-API authentication token.");
 219         gss_release_name(&gss_status, &server);
 220         gss_release_buffer(&gss_status, &gss_recv_token);
 221         gss_release_buffer(&gss_status, &gss_send_token);
 222         gss_delete_sec_context(&gss_status, &gss_context, NULL);
 223         return CURLE_COULDNT_CONNECT;
 224       }
 225
 226     }
 227
 228     gss_release_buffer(&gss_status, &gss_send_token);
 229     gss_release_buffer(&gss_status, &gss_recv_token);
 230     if(gss_major_status != GSS_S_CONTINUE_NEEDED)
 231       break;
 232
 233     /* analyse response */
 234
 235     /*   GSS-API response looks like
 236      * +----+------+-----+----------------+
 237      * |VER | MTYP | LEN |     TOKEN      |
 238      * +----+------+----------------------+
 239      * | 1  |  1   |  2  | up to 2^16 - 1 |
 240      * +----+------+-----+----------------+
 241      */
 242
 243     result = Curl_blockread_all(data, sock, (char *)socksreq, 4, &actualread);
 244     if(result || (actualread != 4)) {
 245       failf(data, "Failed to receive GSS-API authentication response.");
 246       gss_release_name(&gss_status, &server);
 247       gss_delete_sec_context(&gss_status, &gss_context, NULL);
 248       return CURLE_COULDNT_CONNECT;
 249     }
 250
 251     /* ignore the first (VER) byte */
 252     if(socksreq[1] == 255) { /* status / message type */
 253       failf(data, "User was rejected by the SOCKS5 server (%d %d).",
 254             socksreq[0], socksreq[1]);
 255       gss_release_name(&gss_status, &server);
 256       gss_delete_sec_context(&gss_status, &gss_context, NULL);
 257       return CURLE_COULDNT_CONNECT;
 258     }
 259
 260     if(socksreq[1] != 1) { /* status / message type */
 261       failf(data, "Invalid GSS-API authentication response type (%d %d).",
 262             socksreq[0], socksreq[1]);
 263       gss_release_name(&gss_status, &server);
 264       gss_delete_sec_context(&gss_status, &gss_context, NULL);
 265       return CURLE_COULDNT_CONNECT;
 266     }
 267
 268     memcpy(&us_length, socksreq + 2, sizeof(short));
 269     us_length = ntohs(us_length);
 270
 271     gss_recv_token.length = us_length;
 272     gss_recv_token.value = malloc(us_length);
 273     if(!gss_recv_token.value) {
 274       failf(data,
 275             "Could not allocate memory for GSS-API authentication "
 276             "response token.");
 277       gss_release_name(&gss_status, &server);
 278       gss_delete_sec_context(&gss_status, &gss_context, NULL);
 279       return CURLE_OUT_OF_MEMORY;
 280     }
 281
 282     result = Curl_blockread_all(data, sock, (char *)gss_recv_token.value,
 283                                 gss_recv_token.length, &actualread);
 284
 285     if(result || (actualread != us_length)) {
 286       failf(data, "Failed to receive GSS-API authentication token.");
 287       gss_release_name(&gss_status, &server);
 288       gss_release_buffer(&gss_status, &gss_recv_token);
 289       gss_delete_sec_context(&gss_status, &gss_context, NULL);
 290       return CURLE_COULDNT_CONNECT;
 291     }
 292
 293     gss_token = &gss_recv_token;
 294   }
 295
 296   gss_release_name(&gss_status, &server);
 297
 298   /* Everything is good so far, user was authenticated! */
 299   gss_major_status = gss_inquire_context(&gss_minor_status, gss_context,
 300                                          &gss_client_name, NULL, NULL, NULL,
 301                                          NULL, NULL, NULL);
 302   if(check_gss_err(data, gss_major_status,
 303                    gss_minor_status, "gss_inquire_context")) {
 304     gss_delete_sec_context(&gss_status, &gss_context, NULL);
 305     gss_release_name(&gss_status, &gss_client_name);
 306     failf(data, "Failed to determine user name.");
 307     return CURLE_COULDNT_CONNECT;
 308   }
 309   gss_major_status = gss_display_name(&gss_minor_status, gss_client_name,
 310                                       &gss_send_token, NULL);
 311   if(check_gss_err(data, gss_major_status,
 312                    gss_minor_status, "gss_display_name")) {
 313     gss_delete_sec_context(&gss_status, &gss_context, NULL);
 314     gss_release_name(&gss_status, &gss_client_name);
 315     gss_release_buffer(&gss_status, &gss_send_token);
 316     failf(data, "Failed to determine user name.");
 317     return CURLE_COULDNT_CONNECT;
 318   }
 319   user = malloc(gss_send_token.length + 1);
 320   if(!user) {
 321     gss_delete_sec_context(&gss_status, &gss_context, NULL);
 322     gss_release_name(&gss_status, &gss_client_name);
 323     gss_release_buffer(&gss_status, &gss_send_token);
 324     return CURLE_OUT_OF_MEMORY;
 325   }
 326
 327   memcpy(user, gss_send_token.value, gss_send_token.length);
 328   user[gss_send_token.length] = '\0';
 329   gss_release_name(&gss_status, &gss_client_name);
 330   gss_release_buffer(&gss_status, &gss_send_token);
 331   infof(data, "SOCKS5 server authenticated user %s with GSS-API.",user);
 332   free(user);
 333   user = NULL;
 334
 335   /* Do encryption */
 336   socksreq[0] = 1;    /* GSS-API subnegotiation version */
 337   socksreq[1] = 2;    /* encryption message type */
 338
 339   gss_enc = 0; /* no data protection */
 340   /* do confidentiality protection if supported */
 341   if(gss_ret_flags & GSS_C_CONF_FLAG)
 342     gss_enc = 2;
 343   /* else do integrity protection */
 344   else if(gss_ret_flags & GSS_C_INTEG_FLAG)
 345     gss_enc = 1;
 346
 347   infof(data, "SOCKS5 server supports GSS-API %s data protection.",
 348         (gss_enc == 0)?"no":((gss_enc==1)?"integrity":"confidentiality"));
 349   /* force for the moment to no data protection */
 350   gss_enc = 0;
 351   /*
 352    * Sending the encryption type in clear seems wrong. It should be
 353    * protected with gss_seal()/gss_wrap(). See RFC1961 extract below
 354    * The NEC reference implementations on which this is based is
 355    * therefore at fault
 356    *
 357    *  +------+------+------+.......................+
 358    *  + ver  | mtyp | len  |   token               |
 359    *  +------+------+------+.......................+
 360    *  + 0x01 | 0x02 | 0x02 | up to 2^16 - 1 octets |
 361    *  +------+------+------+.......................+
 362    *
 363    *   Where:
 364    *
 365    *  - "ver" is the protocol version number, here 1 to represent the
 366    *    first version of the SOCKS/GSS-API protocol
 367    *
 368    *  - "mtyp" is the message type, here 2 to represent a protection
 369    *    -level negotiation message
 370    *
 371    *  - "len" is the length of the "token" field in octets
 372    *
 373    *  - "token" is the GSS-API encapsulated protection level
 374    *
 375    * The token is produced by encapsulating an octet containing the
 376    * required protection level using gss_seal()/gss_wrap() with conf_req
 377    * set to FALSE.  The token is verified using gss_unseal()/
 378    * gss_unwrap().
 379    *
 380    */
 381   if(data->set.socks5_gssapi_nec) {
 382     us_length = htons((short)1);
 383     memcpy(socksreq + 2, &us_length, sizeof(short));
 384   }
 385   else {
 386     gss_send_token.length = 1;
 387     gss_send_token.value = malloc(1);
 388     if(!gss_send_token.value) {
 389       gss_delete_sec_context(&gss_status, &gss_context, NULL);
 390       return CURLE_OUT_OF_MEMORY;
 391     }
 392     memcpy(gss_send_token.value, &gss_enc, 1);
 393
 394     gss_major_status = gss_wrap(&gss_minor_status, gss_context, 0,
 395                                 GSS_C_QOP_DEFAULT, &gss_send_token,
 396                                 &gss_conf_state, &gss_w_token);
 397
 398     if(check_gss_err(data, gss_major_status, gss_minor_status, "gss_wrap")) {
 399       gss_release_buffer(&gss_status, &gss_send_token);
 400       gss_release_buffer(&gss_status, &gss_w_token);
 401       gss_delete_sec_context(&gss_status, &gss_context, NULL);
 402       failf(data, "Failed to wrap GSS-API encryption value into token.");
 403       return CURLE_COULDNT_CONNECT;
 404     }
 405     gss_release_buffer(&gss_status, &gss_send_token);
 406
 407     us_length = htons((short)gss_w_token.length);
 408     memcpy(socksreq + 2, &us_length, sizeof(short));
 409   }
 410
 411   code = Curl_write_plain(data, sock, (char *)socksreq, 4, &written);
 412   if(code  || (4 != written)) {
 413     failf(data, "Failed to send GSS-API encryption request.");
 414     gss_release_buffer(&gss_status, &gss_w_token);
 415     gss_delete_sec_context(&gss_status, &gss_context, NULL);
 416     return CURLE_COULDNT_CONNECT;
 417   }
 418
 419   if(data->set.socks5_gssapi_nec) {
 420     memcpy(socksreq, &gss_enc, 1);
 421     code = Curl_write_plain(data, sock, socksreq, 1, &written);
 422     if(code || ( 1 != written)) {
 423       failf(data, "Failed to send GSS-API encryption type.");
 424       gss_delete_sec_context(&gss_status, &gss_context, NULL);
 425       return CURLE_COULDNT_CONNECT;
 426     }
 427   }
 428   else {
 429     code = Curl_write_plain(data, sock, (char *)gss_w_token.value,
 430                             gss_w_token.length, &written);
 431     if(code || ((ssize_t)gss_w_token.length != written)) {
 432       failf(data, "Failed to send GSS-API encryption type.");
 433       gss_release_buffer(&gss_status, &gss_w_token);
 434       gss_delete_sec_context(&gss_status, &gss_context, NULL);
 435       return CURLE_COULDNT_CONNECT;
 436     }
 437     gss_release_buffer(&gss_status, &gss_w_token);
 438   }
 439
 440   result = Curl_blockread_all(data, sock, (char *)socksreq, 4, &actualread);
 441   if(result || (actualread != 4)) {
 442     failf(data, "Failed to receive GSS-API encryption response.");
 443     gss_delete_sec_context(&gss_status, &gss_context, NULL);
 444     return CURLE_COULDNT_CONNECT;
 445   }
 446
 447   /* ignore the first (VER) byte */
 448   if(socksreq[1] == 255) { /* status / message type */
 449     failf(data, "User was rejected by the SOCKS5 server (%d %d).",
 450           socksreq[0], socksreq[1]);
 451     gss_delete_sec_context(&gss_status, &gss_context, NULL);
 452     return CURLE_COULDNT_CONNECT;
 453   }
 454
 455   if(socksreq[1] != 2) { /* status / message type */
 456     failf(data, "Invalid GSS-API encryption response type (%d %d).",
 457           socksreq[0], socksreq[1]);
 458     gss_delete_sec_context(&gss_status, &gss_context, NULL);
 459     return CURLE_COULDNT_CONNECT;
 460   }
 461
 462   memcpy(&us_length, socksreq + 2, sizeof(short));
 463   us_length = ntohs(us_length);
 464
 465   gss_recv_token.length = us_length;
 466   gss_recv_token.value = malloc(gss_recv_token.length);
 467   if(!gss_recv_token.value) {
 468     gss_delete_sec_context(&gss_status, &gss_context, NULL);
 469     return CURLE_OUT_OF_MEMORY;
 470   }
 471   result = Curl_blockread_all(data, sock, (char *)gss_recv_token.value,
 472                               gss_recv_token.length, &actualread);
 473
 474   if(result || (actualread != us_length)) {
 475     failf(data, "Failed to receive GSS-API encryptrion type.");
 476     gss_release_buffer(&gss_status, &gss_recv_token);
 477     gss_delete_sec_context(&gss_status, &gss_context, NULL);
 478     return CURLE_COULDNT_CONNECT;
 479   }
 480
 481   if(!data->set.socks5_gssapi_nec) {
 482     gss_major_status = gss_unwrap(&gss_minor_status, gss_context,
 483                                   &gss_recv_token, &gss_w_token,
 484                                   0, GSS_C_QOP_DEFAULT);
 485
 486     if(check_gss_err(data, gss_major_status, gss_minor_status, "gss_unwrap")) {
 487       gss_release_buffer(&gss_status, &gss_recv_token);
 488       gss_release_buffer(&gss_status, &gss_w_token);
 489       gss_delete_sec_context(&gss_status, &gss_context, NULL);
 490       failf(data, "Failed to unwrap GSS-API encryption value into token.");
 491       return CURLE_COULDNT_CONNECT;
 492     }
 493     gss_release_buffer(&gss_status, &gss_recv_token);
 494
 495     if(gss_w_token.length != 1) {
 496       failf(data, "Invalid GSS-API encryption response length (%zu).",
 497             gss_w_token.length);
 498       gss_release_buffer(&gss_status, &gss_w_token);
 499       gss_delete_sec_context(&gss_status, &gss_context, NULL);
 500       return CURLE_COULDNT_CONNECT;
 501     }
 502
 503     memcpy(socksreq, gss_w_token.value, gss_w_token.length);
 504     gss_release_buffer(&gss_status, &gss_w_token);
 505   }
 506   else {
 507     if(gss_recv_token.length != 1) {
 508       failf(data, "Invalid GSS-API encryption response length (%zu).",
 509             gss_recv_token.length);
 510       gss_release_buffer(&gss_status, &gss_recv_token);
 511       gss_delete_sec_context(&gss_status, &gss_context, NULL);
 512       return CURLE_COULDNT_CONNECT;
 513     }
 514
 515     memcpy(socksreq, gss_recv_token.value, gss_recv_token.length);
 516     gss_release_buffer(&gss_status, &gss_recv_token);
 517   }
 518
 519   (void)curlx_nonblock(sock, TRUE);
 520
 521   infof(data, "SOCKS5 access with%s protection granted.",
 522         (socksreq[0] == 0)?"out GSS-API data":
 523         ((socksreq[0] == 1)?" GSS-API integrity":" GSS-API confidentiality"));
 524
 525   conn->socks5_gssapi_enctype = socksreq[0];
 526   if(socksreq[0] == 0)
 527     gss_delete_sec_context(&gss_status, &gss_context, NULL);
 528
 529   return CURLE_OK;
 530 }
 531
 532 #endif /* HAVE_GSSAPI && !CURL_DISABLE_PROXY */