appl/ftp/ftp/gssapi.c

   1 /*
   2  * Copyright (c) 1998 - 2005 Kungliga Tekniska Högskolan
   3  * (Royal Institute of Technology, Stockholm, Sweden).
   4  * All rights reserved.
   5  *
   6  * Redistribution and use in source and binary forms, with or without
   7  * modification, are permitted provided that the following conditions
   8  * are met:
   9  *
  10  * 1. Redistributions of source code must retain the above copyright
  11  *    notice, this list of conditions and the following disclaimer.
  12  *
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in the
  15  *    documentation and/or other materials provided with the distribution.
  16  *
  17  * 3. Neither the name of the Institute nor the names of its contributors
  18  *    may be used to endorse or promote products derived from this software
  19  *    without specific prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
  22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
  25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  31  * SUCH DAMAGE.
  32  */
  33
  34 #ifdef FTP_SERVER
  35 #include "ftpd_locl.h"
  36 #else
  37 #include "ftp_locl.h"
  38 #endif
  39 #include <gssapi/gssapi.h>
  40 #include <gssapi/gssapi_krb5.h>
  41 #include <krb5_err.h>
  42
  43 RCSID("$Id$");
  44
  45 int ftp_do_gss_bindings = 0;
  46 int ftp_do_gss_delegate = 1;
  47
  48 struct gss_data {
  49     gss_ctx_id_t context_hdl;
  50     char *client_name;
  51     gss_cred_id_t delegated_cred_handle;
  52     void *mech_data;
  53 };
  54
  55 static int
  56 gss_init(void *app_data)
  57 {
  58     struct gss_data *d = app_data;
  59     d->context_hdl = GSS_C_NO_CONTEXT;
  60     d->delegated_cred_handle = GSS_C_NO_CREDENTIAL;
  61 #if defined(FTP_SERVER)
  62     return 0;
  63 #else
  64     /* XXX Check the gss mechanism; with  gss_indicate_mechs() ? */
  65 #ifdef KRB5
  66     return !use_kerberos;
  67 #else
  68     return 0;
  69 #endif /* KRB5 */
  70 #endif /* FTP_SERVER */
  71 }
  72
  73 static int
  74 gss_check_prot(void *app_data, int level)
  75 {
  76     if(level == prot_confidential)
  77         return -1;
  78     return 0;
  79 }
  80
  81 static int
  82 gss_decode(void *app_data, void *buf, int len, int level)
  83 {
  84     OM_uint32 maj_stat, min_stat;
  85     gss_buffer_desc input, output;
  86     gss_qop_t qop_state;
  87     int conf_state;
  88     struct gss_data *d = app_data;
  89     size_t ret_len;
  90
  91     input.length = len;
  92     input.value = buf;
  93     maj_stat = gss_unwrap (&min_stat,
  94                            d->context_hdl,
  95                            &input,
  96                            &output,
  97                            &conf_state,
  98                            &qop_state);
  99     if(GSS_ERROR(maj_stat))
 100         return -1;
 101     memmove(buf, output.value, output.length);
 102     ret_len = output.length;
 103     gss_release_buffer(&min_stat, &output);
 104     return ret_len;
 105 }
 106
 107 static int
 108 gss_overhead(void *app_data, int level, int len)
 109 {
 110     return 100; /* dunno? */
 111 }
 112
 113
 114 static int
 115 gss_encode(void *app_data, void *from, int length, int level, void **to)
 116 {
 117     OM_uint32 maj_stat, min_stat;
 118     gss_buffer_desc input, output;
 119     int conf_state;
 120     struct gss_data *d = app_data;
 121
 122     input.length = length;
 123     input.value = from;
 124     maj_stat = gss_wrap (&min_stat,
 125                          d->context_hdl,
 126                          level == prot_private,
 127                          GSS_C_QOP_DEFAULT,
 128                          &input,
 129                          &conf_state,
 130                          &output);
 131     *to = output.value;
 132     return output.length;
 133 }
 134
 135 static void
 136 sockaddr_to_gss_address (struct sockaddr *sa,
 137                          OM_uint32 *addr_type,
 138                          gss_buffer_desc *gss_addr)
 139 {
 140     switch (sa->sa_family) {
 141 #ifdef HAVE_IPV6
 142     case AF_INET6 : {
 143         struct sockaddr_in6 *sin6 = (struct sockaddr_in6 *)sa;
 144
 145         gss_addr->length = 16;
 146         gss_addr->value  = &sin6->sin6_addr;
 147         *addr_type       = GSS_C_AF_INET6;
 148         break;
 149     }
 150 #endif
 151     case AF_INET : {
 152         struct sockaddr_in *sin4 = (struct sockaddr_in *)sa;
 153
 154         gss_addr->length = 4;
 155         gss_addr->value  = &sin4->sin_addr;
 156         *addr_type       = GSS_C_AF_INET;
 157         break;
 158     }
 159     default :
 160         errx (1, "unknown address family %d", sa->sa_family);
 161
 162     }
 163 }
 164
 165 /* end common stuff */
 166
 167 #ifdef FTP_SERVER
 168
 169 static int
 170 gss_adat(void *app_data, void *buf, size_t len)
 171 {
 172     char *p = NULL;
 173     gss_buffer_desc input_token, output_token;
 174     OM_uint32 maj_stat, min_stat;
 175     gss_name_t client_name;
 176     struct gss_data *d = app_data;
 177     gss_channel_bindings_t bindings;
 178
 179     if (ftp_do_gss_bindings) {
 180         bindings = malloc(sizeof(*bindings));
 181         if (bindings == NULL)
 182             errx(1, "out of memory");
 183
 184         sockaddr_to_gss_address (his_addr,
 185                                  &bindings->initiator_addrtype,
 186                                  &bindings->initiator_address);
 187         sockaddr_to_gss_address (ctrl_addr,
 188                                  &bindings->acceptor_addrtype,
 189                                  &bindings->acceptor_address);
 190
 191         bindings->application_data.length = 0;
 192         bindings->application_data.value = NULL;
 193     } else
 194         bindings = GSS_C_NO_CHANNEL_BINDINGS;
 195
 196     input_token.value = buf;
 197     input_token.length = len;
 198
 199     maj_stat = gss_accept_sec_context (&min_stat,
 200                                        &d->context_hdl,
 201                                        GSS_C_NO_CREDENTIAL,
 202                                        &input_token,
 203                                        bindings,
 204                                        &client_name,
 205                                        NULL,
 206                                        &output_token,
 207                                        NULL,
 208                                        NULL,
 209                                        &d->delegated_cred_handle);
 210
 211     if (bindings != GSS_C_NO_CHANNEL_BINDINGS)
 212         free(bindings);
 213
 214     if(output_token.length) {
 215         if(base64_encode(output_token.value, output_token.length, &p) < 0) {
 216             reply(535, "Out of memory base64-encoding.");
 217             return -1;
 218         }
 219         gss_release_buffer(&min_stat, &output_token);
 220     }
 221     if(maj_stat == GSS_S_COMPLETE){
 222         char *name;
 223         gss_buffer_desc export_name;
 224         gss_OID oid;
 225
 226         maj_stat = gss_display_name(&min_stat, client_name,
 227                                     &export_name, &oid);
 228         if(maj_stat != 0) {
 229             reply(500, "Error displaying name");
 230             goto out;
 231         }
 232         /* XXX kerberos */
 233         if(oid != GSS_KRB5_NT_PRINCIPAL_NAME) {
 234             reply(500, "OID not kerberos principal name");
 235             gss_release_buffer(&min_stat, &export_name);
 236             goto out;
 237         }
 238         name = malloc(export_name.length + 1);
 239         if(name == NULL) {
 240             reply(500, "Out of memory");
 241             gss_release_buffer(&min_stat, &export_name);
 242             goto out;
 243         }
 244         memcpy(name, export_name.value, export_name.length);
 245         name[export_name.length] = '\0';
 246         gss_release_buffer(&min_stat, &export_name);
 247         d->client_name = name;
 248         if(p)
 249             reply(235, "ADAT=%s", p);
 250         else
 251             reply(235, "ADAT Complete");
 252         sec_complete = 1;
 253
 254     } else if(maj_stat == GSS_S_CONTINUE_NEEDED) {
 255         if(p)
 256             reply(335, "ADAT=%s", p);
 257         else
 258             reply(335, "OK, need more data");
 259     } else {
 260         OM_uint32 new_stat;
 261         OM_uint32 msg_ctx = 0;
 262         gss_buffer_desc status_string;
 263         gss_display_status(&new_stat,
 264                            min_stat,
 265                            GSS_C_MECH_CODE,
 266                            GSS_C_NO_OID,
 267                            &msg_ctx,
 268                            &status_string);
 269         syslog(LOG_ERR, "gss_accept_sec_context: %.*s",
 270                (int)status_string.length,
 271                (char*)status_string.value);
 272         gss_release_buffer(&new_stat, &status_string);
 273         reply(431, "Security resource unavailable");
 274     }
 275   out:
 276     if (client_name)
 277         gss_release_name(&min_stat, &client_name);
 278     free(p);
 279     return 0;
 280 }
 281
 282 int gss_userok(void*, char*);
 283 int gss_session(void*, char*);
 284
 285 struct sec_server_mech gss_server_mech = {
 286     "GSSAPI",
 287     sizeof(struct gss_data),
 288     gss_init, /* init */
 289     NULL, /* end */
 290     gss_check_prot,
 291     gss_overhead,
 292     gss_encode,
 293     gss_decode,
 294     /* */
 295     NULL,
 296     gss_adat,
 297     NULL, /* pbsz */
 298     NULL, /* ccc */
 299     gss_userok,
 300     gss_session
 301 };
 302
 303 #else /* FTP_SERVER */
 304
 305 extern struct sockaddr *hisctladdr, *myctladdr;
 306
 307 static int
 308 import_name(const char *kname, const char *host, gss_name_t *target_name)
 309 {
 310     OM_uint32 maj_stat, min_stat;
 311     gss_buffer_desc name;
 312     char *str;
 313
 314     name.length = asprintf(&str, "%s@%s", kname, host);
 315     if (str == NULL) {
 316         printf("Out of memory\n");
 317         return AUTH_ERROR;
 318     }
 319     name.value = str;
 320
 321     maj_stat = gss_import_name(&min_stat,
 322                                &name,
 323                                GSS_C_NT_HOSTBASED_SERVICE,
 324                                target_name);
 325     if (GSS_ERROR(maj_stat)) {
 326         OM_uint32 new_stat;
 327         OM_uint32 msg_ctx = 0;
 328         gss_buffer_desc status_string;
 329
 330         gss_display_status(&new_stat,
 331                            min_stat,
 332                            GSS_C_MECH_CODE,
 333                            GSS_C_NO_OID,
 334                            &msg_ctx,
 335                            &status_string);
 336         printf("Error importing name %.*s: %.*s\n",
 337                (int)name.length,
 338                (char *)name.value,
 339                (int)status_string.length,
 340                (char *)status_string.value);
 341         free(name.value);
 342         gss_release_buffer(&new_stat, &status_string);
 343         return AUTH_ERROR;
 344     }
 345     free(name.value);
 346     return 0;
 347 }
 348
 349 static int
 350 gss_auth(void *app_data, char *host)
 351 {
 352
 353     OM_uint32 maj_stat, min_stat;
 354     gss_name_t target_name;
 355     gss_buffer_desc input, output_token;
 356     int context_established = 0;
 357     char *p;
 358     int n;
 359     gss_channel_bindings_t bindings;
 360     struct gss_data *d = app_data;
 361     OM_uint32 mech_flags = GSS_C_MUTUAL_FLAG | GSS_C_SEQUENCE_FLAG;
 362
 363     const char *knames[] = { "ftp", "host", NULL }, **kname = knames;
 364
 365
 366     if(import_name(*kname++, host, &target_name))
 367         return AUTH_ERROR;
 368
 369     input.length = 0;
 370     input.value = NULL;
 371
 372     if (ftp_do_gss_bindings) {
 373         bindings = malloc(sizeof(*bindings));
 374         if (bindings == NULL)
 375             errx(1, "out of memory");
 376
 377         sockaddr_to_gss_address (myctladdr,
 378                                  &bindings->initiator_addrtype,
 379                                  &bindings->initiator_address);
 380         sockaddr_to_gss_address (hisctladdr,
 381                                  &bindings->acceptor_addrtype,
 382                                  &bindings->acceptor_address);
 383
 384         bindings->application_data.length = 0;
 385         bindings->application_data.value = NULL;
 386     } else
 387         bindings = GSS_C_NO_CHANNEL_BINDINGS;
 388
 389     if (ftp_do_gss_delegate)
 390         mech_flags |= GSS_C_DELEG_FLAG;
 391
 392     while(!context_established) {
 393         maj_stat = gss_init_sec_context(&min_stat,
 394                                         GSS_C_NO_CREDENTIAL,
 395                                         &d->context_hdl,
 396                                         target_name,
 397                                         GSS_C_NO_OID,
 398                                         mech_flags,
 399                                         0,
 400                                         bindings,
 401                                         &input,
 402                                         NULL,
 403                                         &output_token,
 404                                         NULL,
 405                                         NULL);
 406         if (GSS_ERROR(maj_stat)) {
 407             OM_uint32 new_stat;
 408             OM_uint32 msg_ctx = 0;
 409             gss_buffer_desc status_string;
 410
 411             d->context_hdl = GSS_C_NO_CONTEXT;
 412
 413             gss_release_name(&min_stat, &target_name);
 414
 415             if(*kname != NULL) {
 416
 417                 if(import_name(*kname++, host, &target_name)) {
 418                     if (bindings != GSS_C_NO_CHANNEL_BINDINGS)
 419                         free(bindings);
 420                     return AUTH_ERROR;
 421                 }
 422                 continue;
 423             }
 424
 425             if (bindings != GSS_C_NO_CHANNEL_BINDINGS)
 426                 free(bindings);
 427
 428             gss_display_status(&new_stat,
 429                                min_stat,
 430                                GSS_C_MECH_CODE,
 431                                GSS_C_NO_OID,
 432                                &msg_ctx,
 433                                &status_string);
 434             printf("Error initializing security context: %.*s\n",
 435                    (int)status_string.length,
 436                    (char*)status_string.value);
 437             gss_release_buffer(&new_stat, &status_string);
 438             return AUTH_CONTINUE;
 439         }
 440
 441         if (input.value) {
 442             free(input.value);
 443             input.value = NULL;
 444             input.length = 0;
 445         }
 446         if (output_token.length != 0) {
 447             base64_encode(output_token.value, output_token.length, &p);
 448             gss_release_buffer(&min_stat, &output_token);
 449             n = command("ADAT %s", p);
 450             free(p);
 451         }
 452         if (GSS_ERROR(maj_stat)) {
 453             if (d->context_hdl != GSS_C_NO_CONTEXT)
 454                 gss_delete_sec_context (&min_stat,
 455                                         &d->context_hdl,
 456                                         GSS_C_NO_BUFFER);
 457             break;
 458         }
 459         if (maj_stat & GSS_S_CONTINUE_NEEDED) {
 460             p = strstr(reply_string, "ADAT=");
 461             if(p == NULL){
 462                 printf("Error: expected ADAT in reply. got: %s\n",
 463                        reply_string);
 464                 if (bindings != GSS_C_NO_CHANNEL_BINDINGS)
 465                     free(bindings);
 466                 return AUTH_ERROR;
 467             } else {
 468                 p+=5;
 469                 input.value = malloc(strlen(p));
 470                 input.length = base64_decode(p, input.value);
 471             }
 472         } else {
 473             if(code != 235) {
 474                 printf("Unrecognized response code: %d\n", code);
 475                 if (bindings != GSS_C_NO_CHANNEL_BINDINGS)
 476                     free(bindings);
 477                 return AUTH_ERROR;
 478             }
 479             context_established = 1;
 480         }
 481     }
 482
 483     gss_release_name(&min_stat, &target_name);
 484
 485     if (bindings != GSS_C_NO_CHANNEL_BINDINGS)
 486         free(bindings);
 487     if (input.value)
 488         free(input.value);
 489
 490     {
 491         gss_name_t targ_name;
 492
 493         maj_stat = gss_inquire_context(&min_stat,
 494                                        d->context_hdl,
 495                                        NULL,
 496                                        &targ_name,
 497                                        NULL,
 498                                        NULL,
 499                                        NULL,
 500                                        NULL,
 501                                        NULL);
 502         if (GSS_ERROR(maj_stat) == 0) {
 503             gss_buffer_desc name;
 504             maj_stat = gss_display_name (&min_stat,
 505                                          targ_name,
 506                                          &name,
 507                                          NULL);
 508             if (GSS_ERROR(maj_stat) == 0) {
 509                 printf("Authenticated to <%.*s>\n",
 510                         (int)name.length,
 511                         (char *)name.value);
 512                 gss_release_buffer(&min_stat, &name);
 513             }
 514             gss_release_name(&min_stat, &targ_name);
 515         } else
 516             printf("Failed to get gss name of peer.\n");
 517     }
 518
 519
 520     return AUTH_OK;
 521 }
 522
 523 struct sec_client_mech gss_client_mech = {
 524     "GSSAPI",
 525     sizeof(struct gss_data),
 526     gss_init,
 527     gss_auth,
 528     NULL, /* end */
 529     gss_check_prot,
 530     gss_overhead,
 531     gss_encode,
 532     gss_decode,
 533 };
 534
 535 #endif /* FTP_SERVER */