source/libads/krb5_setpw.c

   1 /*
   2    Unix SMB/CIFS implementation.
   3    krb5 set password implementation
   4    Copyright (C) Andrew Tridgell 2001
   5    Copyright (C) Remus Koos 2001 (remuskoos@yahoo.com)
   6
   7    This program is free software; you can redistribute it and/or modify
   8    it under the terms of the GNU General Public License as published by
   9    the Free Software Foundation; either version 2 of the License, or
  10    (at your option) any later version.
  11
  12    This program is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15    GNU General Public License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with this program; if not, write to the Free Software
  19    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  20 */
  21
  22 #include "includes.h"
  23
  24 #ifdef HAVE_KRB5
  25
  26 #define DEFAULT_KPASSWD_PORT    464
  27 #define KRB5_KPASSWD_VERS_CHANGEPW      1
  28 #define KRB5_KPASSWD_VERS_SETPW         0xff80
  29 #define KRB5_KPASSWD_ACCESSDENIED       5
  30 #define KRB5_KPASSWD_BAD_VERSION        6
  31
  32 /* This implements the Kerb password change protocol as specifed in
  33  * kerb-chg-password-02.txt
  34  */
  35 static DATA_BLOB encode_krb5_setpw(const char *principal, const char *password)
  36 {
  37         char* princ_part1 = NULL;
  38         char* princ_part2 = NULL;
  39         char* realm = NULL;
  40         char* c;
  41         char* princ;
  42
  43         ASN1_DATA req;
  44         DATA_BLOB ret;
  45
  46
  47         princ = strdup(principal);
  48
  49         if ((c = strchr(princ, '/')) == NULL) {
  50             c = princ;
  51         } else {
  52             *c = '\0';
  53             c++;
  54             princ_part1 = princ;
  55         }
  56
  57         princ_part2 = c;
  58
  59         if ((c = strchr(c, '@')) != NULL) {
  60             *c = '\0';
  61             c++;
  62             realm = c;
  63         }
  64
  65         memset(&req, 0, sizeof(req));
  66
  67         asn1_push_tag(&req, ASN1_SEQUENCE(0));
  68         asn1_push_tag(&req, ASN1_CONTEXT(0));
  69         asn1_write_OctetString(&req, password, strlen(password));
  70         asn1_pop_tag(&req);
  71
  72         asn1_push_tag(&req, ASN1_CONTEXT(1));
  73         asn1_push_tag(&req, ASN1_SEQUENCE(0));
  74
  75         asn1_push_tag(&req, ASN1_CONTEXT(0));
  76         asn1_write_Integer(&req, 1);
  77         asn1_pop_tag(&req);
  78
  79         asn1_push_tag(&req, ASN1_CONTEXT(1));
  80         asn1_push_tag(&req, ASN1_SEQUENCE(0));
  81
  82         if (princ_part1)
  83             asn1_write_GeneralString(&req, princ_part1);
  84
  85         asn1_write_GeneralString(&req, princ_part2);
  86         asn1_pop_tag(&req);
  87         asn1_pop_tag(&req);
  88         asn1_pop_tag(&req);
  89         asn1_pop_tag(&req);
  90
  91         asn1_push_tag(&req, ASN1_CONTEXT(2));
  92         asn1_write_GeneralString(&req, realm);
  93         asn1_pop_tag(&req);
  94         asn1_pop_tag(&req);
  95
  96         ret = data_blob(req.data, req.length);
  97         asn1_free(&req);
  98
  99         free(princ);
 100
 101         return ret;
 102 }
 103
 104 static krb5_error_code build_setpw_request(krb5_context context,
 105                                            krb5_auth_context auth_context,
 106                                            krb5_data *ap_req,
 107                                            const char *princ,
 108                                            const char *passwd,
 109                                            krb5_data *packet)
 110 {
 111         krb5_error_code ret;
 112         krb5_data cipherpw;
 113         krb5_data encoded_setpw;
 114         krb5_replay_data replay;
 115         char *p;
 116         DATA_BLOB setpw;
 117
 118         ret = krb5_auth_con_setflags(context,
 119                                      auth_context,KRB5_AUTH_CONTEXT_DO_SEQUENCE);
 120         if (ret) {
 121                 DEBUG(1,("krb5_auth_con_setflags failed (%s)\n",
 122                          error_message(ret)));
 123                 return ret;
 124         }
 125
 126         setpw = encode_krb5_setpw(princ, passwd);
 127
 128         encoded_setpw.data = setpw.data;
 129         encoded_setpw.length = setpw.length;
 130
 131         ret = krb5_mk_priv(context, auth_context,
 132                            &encoded_setpw, &cipherpw, &replay);
 133
 134         data_blob_free(&setpw);         /*from 'encode_krb5_setpw(...)' */
 135
 136         if (ret) {
 137                 DEBUG(1,("krb5_mk_priv failed (%s)\n", error_message(ret)));
 138                 return ret;
 139         }
 140
 141         packet->data = (char *)malloc(ap_req->length + cipherpw.length + 6);
 142
 143         /* see the RFC for details */
 144         p = packet->data + 2;
 145         RSSVAL(p, 0, 0xff80); p += 2;
 146         RSSVAL(p, 0, ap_req->length); p += 2;
 147         memcpy(p, ap_req->data, ap_req->length); p += ap_req->length;
 148         memcpy(p, cipherpw.data, cipherpw.length); p += cipherpw.length;
 149         packet->length = PTR_DIFF(p,packet->data);
 150         RSSVAL(packet->data, 0, packet->length);
 151
 152         free(cipherpw.data);    /* from 'krb5_mk_priv(...)' */
 153
 154         return 0;
 155 }
 156
 157 static krb5_error_code parse_setpw_reply(krb5_context context,
 158                                          krb5_auth_context auth_context,
 159                                          krb5_data *packet)
 160 {
 161         krb5_data ap_rep;
 162         char *p;
 163         int vnum, ret, res_code;
 164         krb5_data cipherresult;
 165         krb5_data clearresult;
 166         krb5_ap_rep_enc_part *ap_rep_enc;
 167         krb5_replay_data replay;
 168
 169         if (packet->length < 4) {
 170                 return KRB5KRB_AP_ERR_MODIFIED;
 171         }
 172
 173         p = packet->data;
 174
 175         if (packet->data[0] == 0x7e || packet->data[0] == 0x5e) {
 176                 /* it's an error packet. We should parse it ... */
 177                 DEBUG(1,("Got error packet 0x%x from kpasswd server\n",
 178                          packet->data[0]));
 179                 return KRB5KRB_AP_ERR_MODIFIED;
 180         }
 181
 182         if (RSVAL(p, 0) != packet->length) {
 183                 DEBUG(1,("Bad packet length (%d/%d) from kpasswd server\n",
 184                          RSVAL(p, 0), packet->length));
 185                 return KRB5KRB_AP_ERR_MODIFIED;
 186         }
 187
 188         p += 2;
 189
 190         vnum = RSVAL(p, 0); p += 2;
 191
 192         if (vnum != KRB5_KPASSWD_VERS_SETPW && vnum != KRB5_KPASSWD_VERS_CHANGEPW) {
 193                 DEBUG(1,("Bad vnum (%d) from kpasswd server\n", vnum));
 194                 return KRB5KDC_ERR_BAD_PVNO;
 195         }
 196
 197         ap_rep.length = RSVAL(p, 0); p += 2;
 198
 199         if (p + ap_rep.length >= packet->data + packet->length) {
 200                 DEBUG(1,("ptr beyond end of packet from kpasswd server\n"));
 201                 return KRB5KRB_AP_ERR_MODIFIED;
 202         }
 203
 204         if (ap_rep.length == 0) {
 205                 DEBUG(1,("got unencrypted setpw result?!\n"));
 206                 return KRB5KRB_AP_ERR_MODIFIED;
 207         }
 208
 209         /* verify ap_rep */
 210         ap_rep.data = p;
 211         p += ap_rep.length;
 212
 213         ret = krb5_rd_rep(context, auth_context, &ap_rep, &ap_rep_enc);
 214         if (ret) {
 215                 DEBUG(1,("failed to rd setpw reply (%s)\n", error_message(ret)));
 216                 return KRB5KRB_AP_ERR_MODIFIED;
 217         }
 218
 219         krb5_free_ap_rep_enc_part(context, ap_rep_enc);
 220
 221         cipherresult.data = p;
 222         cipherresult.length = (packet->data + packet->length) - p;
 223
 224         ret = krb5_rd_priv(context, auth_context, &cipherresult, &clearresult,
 225                            &replay);
 226         if (ret) {
 227                 DEBUG(1,("failed to decrypt setpw reply (%s)\n", error_message(ret)));
 228                 return KRB5KRB_AP_ERR_MODIFIED;
 229         }
 230
 231         if (clearresult.length < 2) {
 232                 free(clearresult.data);
 233                 ret = KRB5KRB_AP_ERR_MODIFIED;
 234                 return KRB5KRB_AP_ERR_MODIFIED;
 235         }
 236
 237         p = clearresult.data;
 238
 239         res_code = RSVAL(p, 0);
 240
 241         free(clearresult.data);
 242
 243         if ((res_code < KRB5_KPASSWD_SUCCESS) ||
 244             (res_code >= KRB5_KPASSWD_ACCESSDENIED)) {
 245                 return KRB5KRB_AP_ERR_MODIFIED;
 246         }
 247
 248         return 0;
 249 }
 250
 251 ADS_STATUS krb5_set_password(const char *kdc_host, const char *princ, const char *newpw,
 252                              int time_offset)
 253 {
 254         krb5_context context;
 255         krb5_auth_context auth_context = NULL;
 256         krb5_principal principal;
 257         char *princ_name;
 258         char *realm;
 259         krb5_creds creds, *credsp;
 260         krb5_ccache ccache;
 261         krb5_data ap_req, chpw_req, chpw_rep;
 262         int ret, sock, addr_len;
 263         struct sockaddr remote_addr, local_addr;
 264         krb5_address local_kaddr, remote_kaddr;
 265
 266         ret = krb5_init_context(&context);
 267         if (ret) {
 268                 DEBUG(1,("Failed to init krb5 context (%s)\n", error_message(ret)));
 269                 return ADS_ERROR_KRB5(ret);
 270         }
 271
 272         if (time_offset != 0) {
 273                 krb5_set_real_time(context, time(NULL) + time_offset, 0);
 274         }
 275
 276         ret = krb5_cc_default(context, &ccache);
 277         if (ret) {
 278                 krb5_free_context(context);
 279                 DEBUG(1,("Failed to get default creds (%s)\n", error_message(ret)));
 280                 return ADS_ERROR_KRB5(ret);
 281         }
 282
 283         ZERO_STRUCT(creds);
 284
 285         realm = strchr(princ, '@');
 286         realm++;
 287
 288         asprintf(&princ_name, "kadmin/changepw@%s", realm);
 289         ret = krb5_parse_name(context, princ_name, &creds.server);
 290         if (ret) {
 291                 krb5_free_context(context);
 292                 DEBUG(1,("Failed to parse kadmin/changepw (%s)\n", error_message(ret)));
 293                 return ADS_ERROR_KRB5(ret);
 294         }
 295         free(princ_name);
 296
 297         /* parse the principal we got as a function argument */
 298         ret = krb5_parse_name(context, princ, &principal);
 299         if (ret) {
 300                 krb5_free_context(context);
 301                 DEBUG(1,("Failed to parse %s (%s)\n", princ_name, error_message(ret)));
 302                 return ADS_ERROR_KRB5(ret);
 303         }
 304
 305         krb5_princ_set_realm(context, creds.server,
 306                              krb5_princ_realm(context, principal));
 307
 308         ret = krb5_cc_get_principal(context, ccache, &creds.client);
 309         if (ret) {
 310                 krb5_free_principal(context, principal);
 311                 krb5_free_context(context);
 312                 DEBUG(1,("Failed to get principal from ccache (%s)\n",
 313                          error_message(ret)));
 314                 return ADS_ERROR_KRB5(ret);
 315         }
 316
 317         ret = krb5_get_credentials(context, 0, ccache, &creds, &credsp);
 318         if (ret) {
 319                 krb5_free_principal(context, creds.client);
 320                 krb5_free_principal(context, principal);
 321                 krb5_free_context(context);
 322                 DEBUG(1,("krb5_get_credentials failed (%s)\n", error_message(ret)));
 323                 return ADS_ERROR_KRB5(ret);
 324         }
 325
 326         /* we might have to call krb5_free_creds(...) from now on ... */
 327         ret = krb5_mk_req_extended(context, &auth_context, AP_OPTS_USE_SUBKEY,
 328                                    NULL, credsp, &ap_req);
 329         if (ret) {
 330                 krb5_free_creds(context, credsp);
 331                 krb5_free_principal(context, creds.client);
 332                 krb5_free_principal(context, principal);
 333                 krb5_free_context(context);
 334                 DEBUG(1,("krb5_mk_req_extended failed (%s)\n", error_message(ret)));
 335                 return ADS_ERROR_KRB5(ret);
 336         }
 337
 338         sock = open_udp_socket(kdc_host, DEFAULT_KPASSWD_PORT);
 339         if (sock == -1) {
 340                 int rc = errno;
 341                 free(ap_req.data);
 342                 krb5_free_creds(context, credsp);
 343                 krb5_free_principal(context, creds.client);
 344                 krb5_free_principal(context, principal);
 345                 krb5_free_context(context);
 346                 DEBUG(1,("failed to open kpasswd socket to %s (%s)\n",
 347                          kdc_host, strerror(errno)));
 348                 return ADS_ERROR_SYSTEM(rc);
 349         }
 350
 351         addr_len = sizeof(remote_addr);
 352         getpeername(sock, &remote_addr, &addr_len);
 353         addr_len = sizeof(local_addr);
 354         getsockname(sock, &local_addr, &addr_len);
 355
 356         remote_kaddr.addrtype = ADDRTYPE_INET;
 357         remote_kaddr.length = sizeof(((struct sockaddr_in *)&remote_addr)->sin_addr);
 358         remote_kaddr.contents = (char *)&(((struct sockaddr_in *)&remote_addr)->sin_addr);
 359         local_kaddr.addrtype = ADDRTYPE_INET;
 360         local_kaddr.length = sizeof(((struct sockaddr_in *)&local_addr)->sin_addr);
 361         local_kaddr.contents = (char *)&(((struct sockaddr_in *)&local_addr)->sin_addr);
 362
 363         ret = krb5_auth_con_setaddrs(context, auth_context, &local_kaddr, NULL);
 364         if (ret) {
 365                 close(sock);
 366                 free(ap_req.data);
 367                 krb5_free_creds(context, credsp);
 368                 krb5_free_principal(context, creds.client);
 369                 krb5_free_principal(context, principal);
 370                 krb5_free_context(context);
 371                 DEBUG(1,("krb5_auth_con_setaddrs failed (%s)\n", error_message(ret)));
 372                 return ADS_ERROR_KRB5(ret);
 373         }
 374
 375         ret = build_setpw_request(context, auth_context, &ap_req,
 376                                   princ, newpw, &chpw_req);
 377         if (ret) {
 378                 close(sock);
 379                 free(ap_req.data);
 380                 krb5_free_creds(context, credsp);
 381                 krb5_free_principal(context, creds.client);
 382                 krb5_free_principal(context, principal);
 383                 krb5_free_context(context);
 384                 DEBUG(1,("build_setpw_request failed (%s)\n", error_message(ret)));
 385                 return ADS_ERROR_KRB5(ret);
 386         }
 387
 388         if (write(sock, chpw_req.data, chpw_req.length) != chpw_req.length) {
 389                 close(sock);
 390                 free(chpw_req.data);
 391                 free(ap_req.data);
 392                 krb5_free_creds(context, credsp);
 393                 krb5_free_principal(context, creds.client);
 394                 krb5_free_principal(context, principal);
 395                 krb5_free_context(context);
 396                 DEBUG(1,("send of chpw failed (%s)\n", strerror(errno)));
 397                 return ADS_ERROR_SYSTEM(errno);
 398         }
 399
 400         free(chpw_req.data);
 401
 402         chpw_rep.length = 1500;
 403         chpw_rep.data = (char *) malloc(chpw_rep.length);
 404
 405         ret = read(sock, chpw_rep.data, chpw_rep.length);
 406         if (ret < 0) {
 407                 close(sock);
 408                 free(chpw_rep.data);
 409                 free(ap_req.data);
 410                 krb5_free_creds(context, credsp);
 411                 krb5_free_principal(context, creds.client);
 412                 krb5_free_principal(context, principal);
 413                 krb5_free_context(context);
 414                 DEBUG(1,("recv of chpw reply failed (%s)\n", strerror(errno)));
 415                 return ADS_ERROR_SYSTEM(errno);
 416         }
 417
 418         close(sock);
 419         chpw_rep.length = ret;
 420
 421         ret = krb5_auth_con_setaddrs(context, auth_context, NULL,&remote_kaddr);
 422         if (ret) {
 423                 free(chpw_rep.data);
 424                 free(ap_req.data);
 425                 krb5_free_creds(context, credsp);
 426                 krb5_free_principal(context, creds.client);
 427                 krb5_free_principal(context, principal);
 428                 krb5_free_context(context);
 429                 DEBUG(1,("krb5_auth_con_setaddrs on reply failed (%s)\n",
 430                          error_message(ret)));
 431                 return ADS_ERROR_KRB5(ret);
 432         }
 433
 434         ret = parse_setpw_reply(context, auth_context, &chpw_rep);
 435         free(chpw_rep.data);
 436
 437         if (ret) {
 438                 free(ap_req.data);
 439                 krb5_free_creds(context, credsp);
 440                 krb5_free_principal(context, creds.client);
 441                 krb5_free_principal(context, principal);
 442                 krb5_free_context(context);
 443                 DEBUG(1,("parse_setpw_reply failed (%s)\n",
 444                          error_message(ret)));
 445                 return ADS_ERROR_KRB5(ret);
 446         }
 447
 448         free(ap_req.data);
 449         krb5_free_creds(context, credsp);
 450         krb5_free_principal(context, creds.client);
 451         krb5_free_principal(context, principal);
 452         krb5_free_context(context);
 453
 454         return ADS_SUCCESS;
 455 }
 456
 457
 458 ADS_STATUS kerberos_set_password(const char *kpasswd_server,
 459                                  const char *auth_principal, const char *auth_password,
 460                                  const char *target_principal, const char *new_password,
 461                                  int time_offset)
 462 {
 463     int ret;
 464
 465     if ((ret = kerberos_kinit_password(auth_principal, auth_password, time_offset))) {
 466         DEBUG(1,("Failed kinit for principal %s (%s)\n", auth_principal, error_message(ret)));
 467         return ADS_ERROR_KRB5(ret);
 468     }
 469
 470     return krb5_set_password(kpasswd_server, target_principal, new_password, time_offset);
 471 }
 472
 473
 474 #endif