source4/libcli/auth/gensec_krb5.c

   1 /*
   2    Unix SMB/CIFS implementation.
   3
   4    Kerberos backend for GENSEC
   5
   6    Copyright (C) Andrew Bartlett <abartlet@samba.org> 2004
   7    Copyright (C) Andrew Tridgell 2001
   8    Copyright (C) Luke Howard 2002-2003
   9
  10    This program is free software; you can redistribute it and/or modify
  11    it under the terms of the GNU General Public License as published by
  12    the Free Software Foundation; either version 2 of the License, or
  13    (at your option) any later version.
  14
  15    This program is distributed in the hope that it will be useful,
  16    but WITHOUT ANY WARRANTY; without even the implied warranty of
  17    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  18    GNU General Public License for more details.
  19
  20
  21    You should have received a copy of the GNU General Public License
  22    along with this program; if not, write to the Free Software
  23    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  24 */
  25
  26 #include "includes.h"
  27
  28 #undef DBGC_CLASS
  29 #define DBGC_CLASS DBGC_AUTH
  30
  31 enum GENSEC_KRB5_STATE {
  32         GENSEC_KRB5_SERVER_START,
  33         GENSEC_KRB5_CLIENT_START,
  34         GENSEC_KRB5_CLIENT_MUTUAL_AUTH,
  35         GENSEC_KRB5_DONE
  36 };
  37
  38 struct gensec_krb5_state {
  39         TALLOC_CTX *mem_ctx;
  40         DATA_BLOB session_key;
  41         DATA_BLOB pac;
  42         enum GENSEC_KRB5_STATE state_position;
  43         krb5_context krb5_context;
  44         krb5_auth_context krb5_auth_context;
  45         krb5_ccache krb5_ccache;
  46         krb5_data ticket;
  47 };
  48
  49 static NTSTATUS gensec_krb5_start(struct gensec_security *gensec_security)
  50 {
  51         struct gensec_krb5_state *gensec_krb5_state;
  52         krb5_error_code ret = 0;
  53
  54         TALLOC_CTX *mem_ctx = talloc_init("gensec_krb5");
  55         if (!mem_ctx) {
  56                 return NT_STATUS_NO_MEMORY;
  57         }
  58
  59         gensec_krb5_state = talloc_p(mem_ctx, struct gensec_krb5_state);
  60         if (!gensec_krb5_state) {
  61                 return NT_STATUS_NO_MEMORY;
  62         }
  63
  64         gensec_krb5_state->mem_ctx = mem_ctx;
  65
  66         gensec_security->private_data = gensec_krb5_state;
  67
  68         initialize_krb5_error_table();
  69         gensec_krb5_state->krb5_context = NULL;
  70         gensec_krb5_state->krb5_auth_context = NULL;
  71         gensec_krb5_state->krb5_ccache = NULL;
  72         ZERO_STRUCT(gensec_krb5_state->ticket);
  73         gensec_krb5_state->session_key = data_blob(NULL, 0);
  74
  75         ret = krb5_init_context(&gensec_krb5_state->krb5_context);
  76         if (ret) {
  77                 DEBUG(1,("gensec_krb5_start: krb5_init_context failed (%s)\n", error_message(ret)));
  78                 return NT_STATUS_INTERNAL_ERROR;
  79         }
  80
  81         if (lp_realm() && *lp_realm()) {
  82                 ret = krb5_set_default_realm(gensec_krb5_state->krb5_context, lp_realm());
  83                 if (ret) {
  84                         DEBUG(1,("gensec_krb5_start: krb5_set_default_realm failed (%s)\n", error_message(ret)));
  85                         return NT_STATUS_INTERNAL_ERROR;
  86                 }
  87         }
  88
  89         ret = krb5_auth_con_init(gensec_krb5_state->krb5_context, &gensec_krb5_state->krb5_auth_context);
  90         if (ret) {
  91                 DEBUG(1,("gensec_krb5_start: krb5_auth_con_init failed (%s)\n", error_message(ret)));
  92                 return NT_STATUS_INTERNAL_ERROR;
  93         }
  94
  95         return NT_STATUS_OK;
  96 }
  97
  98 static NTSTATUS gensec_krb5_server_start(struct gensec_security *gensec_security)
  99 {
 100         NTSTATUS nt_status;
 101         struct gensec_krb5_state *gensec_krb5_state;
 102
 103         nt_status = gensec_krb5_start(gensec_security);
 104         if (!NT_STATUS_IS_OK(nt_status)) {
 105                 return nt_status;
 106         }
 107
 108         gensec_krb5_state = gensec_security->private_data;
 109         gensec_krb5_state->state_position = GENSEC_KRB5_SERVER_START;
 110
 111         return NT_STATUS_OK;
 112 }
 113
 114 static NTSTATUS gensec_krb5_client_start(struct gensec_security *gensec_security)
 115 {
 116         struct gensec_krb5_state *gensec_krb5_state;
 117         krb5_error_code ret;
 118         NTSTATUS nt_status;
 119
 120         nt_status = gensec_krb5_start(gensec_security);
 121         if (!NT_STATUS_IS_OK(nt_status)) {
 122                 return nt_status;
 123         }
 124
 125         gensec_krb5_state = gensec_security->private_data;
 126         gensec_krb5_state->state_position = GENSEC_KRB5_CLIENT_START;
 127
 128         /* TODO: This is effecivly a static/global variable... */
 129         ret = krb5_cc_default(gensec_krb5_state->krb5_context, &gensec_krb5_state->krb5_ccache);
 130         if (ret) {
 131                 DEBUG(1,("krb5_cc_default failed (%s)\n",
 132                          error_message(ret)));
 133                 return NT_STATUS_INTERNAL_ERROR;
 134         }
 135
 136         while (1) {
 137                 if (gensec_security->target.principal) {
 138                         DEBUG(5, ("Finding ticket for target [%s]\n", gensec_security->target.principal));
 139                         ret = ads_krb5_mk_req(gensec_krb5_state->krb5_context,
 140                                               &gensec_krb5_state->krb5_auth_context,
 141                                               AP_OPTS_USE_SUBKEY | AP_OPTS_MUTUAL_REQUIRED,
 142                                               gensec_security->target.principal,
 143                                               gensec_krb5_state->krb5_ccache,
 144                                               &gensec_krb5_state->ticket);
 145                         if (ret) {
 146                                 DEBUG(1,("ads_krb5_mk_req failed (%s)\n",
 147                                          error_message(ret)));
 148                         }
 149                 } else {
 150                         krb5_data in_data;
 151                         in_data.length = 0;
 152                         const char *hostname = gensec_get_target_hostname(gensec_security);
 153                         if (!hostname) {
 154                                 DEBUG(1, ("Could not determine hostname for target computer, cannot use kerberos\n"));
 155                                 return NT_STATUS_ACCESS_DENIED;
 156                         }
 157                         ret = krb5_mk_req(gensec_krb5_state->krb5_context,
 158                                           &gensec_krb5_state->krb5_auth_context,
 159                                           AP_OPTS_USE_SUBKEY | AP_OPTS_MUTUAL_REQUIRED,
 160                                           gensec_get_target_service(gensec_security),
 161                                           hostname,
 162                                           &in_data, gensec_krb5_state->krb5_ccache,
 163                                           &gensec_krb5_state->ticket);
 164                         if (ret) {
 165                                 DEBUG(1,("krb5_mk_req failed (%s)\n",
 166                                          error_message(ret)));
 167                         }
 168
 169                 }
 170                 switch (ret) {
 171                 case 0:
 172                         return NT_STATUS_OK;
 173                 case KRB5KDC_ERR_S_PRINCIPAL_UNKNOWN:
 174                         DEBUG(3, ("Server is not registered with our KDC: %s\n",
 175                                   error_message(ret)));
 176                         return NT_STATUS_ACCESS_DENIED;
 177                 case KRB5KDC_ERR_PREAUTH_FAILED:
 178                 case KRB5KRB_AP_ERR_TKT_EXPIRED:
 179                 case KRB5_CC_END:
 180                 {
 181                         DEBUG(3, ("kerberos: %s\n",
 182                                   error_message(ret)));
 183                         /* fall down to remaining code */
 184                 }
 185                 /* just don't print a message for these really ordinary messages */
 186                 case KRB5_FCC_NOFILE:
 187                 case KRB5_CC_NOTFOUND:
 188                 {
 189                         char *password;
 190                         time_t kdc_time;
 191                         nt_status = gensec_get_password(gensec_security,
 192                                                         gensec_security->mem_ctx,
 193                                                         &password);
 194                         if (!NT_STATUS_IS_OK(nt_status)) {
 195                                 return nt_status;
 196                         }
 197
 198                         ret = kerberos_kinit_password_cc(gensec_krb5_state->krb5_context, gensec_krb5_state->krb5_ccache,
 199                                                          gensec_get_client_principal(gensec_security, gensec_security->mem_ctx),
 200                                                          password, NULL, &kdc_time);
 201
 202                         /* cope with ticket being in the future due to clock skew */
 203                         if ((unsigned)kdc_time > time(NULL)) {
 204                                 time_t t = time(NULL);
 205                                 int time_offset =(unsigned)kdc_time-t;
 206                                 DEBUG(4,("Advancing clock by %d seconds to cope with clock skew\n", time_offset));
 207                                 krb5_set_real_time(gensec_krb5_state->krb5_context, t + time_offset + 1, 0);
 208                         }
 209
 210                         if (ret) {
 211                                 DEBUG(1,("kinit failed (%s)\n",
 212                                          error_message(ret)));
 213                                 return NT_STATUS_WRONG_PASSWORD;
 214                         }
 215                         break;
 216                 }
 217                 default:
 218                         DEBUG(0, ("kerberos: %s\n",
 219                                   error_message(ret)));
 220                         return NT_STATUS_UNSUCCESSFUL;
 221                 }
 222         }
 223 }
 224
 225 static void gensec_krb5_end(struct gensec_security *gensec_security)
 226 {
 227         struct gensec_krb5_state *gensec_krb5_state = gensec_security->private_data;
 228
 229         if (gensec_krb5_state->ticket.length) {
 230         /* Hmm, heimdal dooesn't have this - what's the correct call? */
 231 #ifdef HAVE_KRB5_FREE_DATA_CONTENTS
 232                 krb5_free_data_contents(gensec_krb5_state->krb5_context, &gensec_krb5_state->ticket);
 233 #endif
 234         }
 235         if (gensec_krb5_state->krb5_ccache) {
 236                 /* Removed by jra. They really need to fix their kerberos so we don't leak memory.
 237                    JERRY -- disabled since it causes heimdal 0.6.1rc3 to die
 238                    SuSE 9.1 Pro
 239                 */
 240 #if 0 /* redisabled by gd :) at least until any official heimdal version has it fixed. */
 241                 krb5_cc_close(context, gensec_krb5_state->krb5_ccache);
 242 #endif
 243         }
 244
 245         if (gensec_krb5_state->krb5_auth_context) {
 246                 krb5_auth_con_free(gensec_krb5_state->krb5_context,
 247                                    gensec_krb5_state->krb5_auth_context);
 248         }
 249
 250         if (gensec_krb5_state->krb5_context) {
 251                 krb5_free_context(gensec_krb5_state->krb5_context);
 252         }
 253
 254         talloc_destroy(gensec_krb5_state->mem_ctx);
 255         gensec_security->private_data = NULL;
 256 }
 257
 258
 259 /**
 260  * Next state function for the Krb5 GENSEC mechanism
 261  *
 262  * @param gensec_krb5_state KRB5 State
 263  * @param out_mem_ctx The TALLOC_CTX for *out to be allocated on
 264  * @param in The request, as a DATA_BLOB
 265  * @param out The reply, as an talloc()ed DATA_BLOB, on *out_mem_ctx
 266  * @return Error, MORE_PROCESSING_REQUIRED if a reply is sent,
 267  *                or NT_STATUS_OK if the user is authenticated.
 268  */
 269
 270 static NTSTATUS gensec_krb5_update(struct gensec_security *gensec_security, TALLOC_CTX *out_mem_ctx,
 271                                       const DATA_BLOB in, DATA_BLOB *out)
 272 {
 273         struct gensec_krb5_state *gensec_krb5_state = gensec_security->private_data;
 274         krb5_error_code ret = 0;
 275         DATA_BLOB pac;
 276         NTSTATUS nt_status;
 277
 278         switch (gensec_krb5_state->state_position) {
 279         case GENSEC_KRB5_CLIENT_START:
 280         {
 281                 if (ret) {
 282                         DEBUG(1,("ads_krb5_mk_req (request ticket) failed (%s)\n",
 283                                  error_message(ret)));
 284                         nt_status = NT_STATUS_LOGON_FAILURE;
 285                 } else {
 286                         DATA_BLOB unwrapped_out;
 287                         unwrapped_out = data_blob_talloc(out_mem_ctx, gensec_krb5_state->ticket.data, gensec_krb5_state->ticket.length);
 288
 289                         /* wrap that up in a nice GSS-API wrapping */
 290                         *out = gensec_gssapi_gen_krb5_wrap(out_mem_ctx, &unwrapped_out, TOK_ID_KRB_AP_REQ);
 291
 292                         gensec_krb5_state->state_position = GENSEC_KRB5_CLIENT_MUTUAL_AUTH;
 293                         nt_status = NT_STATUS_MORE_PROCESSING_REQUIRED;
 294                 }
 295
 296                 return nt_status;
 297         }
 298
 299         case GENSEC_KRB5_CLIENT_MUTUAL_AUTH:
 300         {
 301                 krb5_data inbuf;
 302                 krb5_ap_rep_enc_part *repl = NULL;
 303                 uint8 tok_id[2];
 304                 DATA_BLOB unwrapped_in;
 305
 306                 if (!gensec_gssapi_parse_krb5_wrap(out_mem_ctx, &in, &unwrapped_in, tok_id)) {
 307                         return NT_STATUS_INVALID_PARAMETER;
 308                 }
 309                 /* TODO: check the tok_id */
 310
 311                 inbuf.data = unwrapped_in.data;
 312                 inbuf.length = unwrapped_in.length;
 313                 ret = krb5_rd_rep(gensec_krb5_state->krb5_context,
 314                                   gensec_krb5_state->krb5_auth_context,
 315                                   &inbuf, &repl);
 316                 if (ret) {
 317                         DEBUG(1,("krb5_rd_rep (mutual authentication) failed (%s)\n",
 318                                  error_message(ret)));
 319                         dump_data_pw("Mutual authentication message:\n", in.data, in.length);
 320                         nt_status = NT_STATUS_ACCESS_DENIED;
 321                 } else {
 322                         *out = data_blob(NULL, 0);
 323                         nt_status = NT_STATUS_OK;
 324                         gensec_krb5_state->state_position = GENSEC_KRB5_DONE;
 325                 }
 326                 if (repl) {
 327                         krb5_free_ap_rep_enc_part(gensec_krb5_state->krb5_context, repl);
 328                 }
 329                 return nt_status;
 330         }
 331
 332         case GENSEC_KRB5_SERVER_START:
 333         {
 334                 char *principal;
 335                 DATA_BLOB unwrapped_in;
 336                 DATA_BLOB unwrapped_out;
 337                 uint8 tok_id[2];
 338
 339                 /* Parse the GSSAPI wrapping, if it's there... (win2k3 allows it to be omited) */
 340                 if (!gensec_gssapi_parse_krb5_wrap(out_mem_ctx, &in, &unwrapped_in, tok_id)) {
 341                         nt_status = ads_verify_ticket(out_mem_ctx,
 342                                                       gensec_krb5_state->krb5_context,
 343                                                       gensec_krb5_state->krb5_auth_context,
 344                                                       lp_realm(), &in,
 345                                                       &principal, &pac, &unwrapped_out);
 346                 } else {
 347                         /* TODO: check the tok_id */
 348                         nt_status = ads_verify_ticket(out_mem_ctx,
 349                                                       gensec_krb5_state->krb5_context,
 350                                                       gensec_krb5_state->krb5_auth_context,
 351                                                       lp_realm(), &unwrapped_in,
 352                                                       &principal, &pac, &unwrapped_out);
 353                 }
 354
 355                 gensec_krb5_state->pac = data_blob_talloc_steal(out_mem_ctx, gensec_krb5_state->mem_ctx,
 356                                                                 &pac);
 357                 /* TODO: parse the pac */
 358
 359                 if (NT_STATUS_IS_OK(nt_status)) {
 360                         gensec_krb5_state->state_position = GENSEC_KRB5_DONE;
 361                         /* wrap that up in a nice GSS-API wrapping */
 362                         *out = gensec_gssapi_gen_krb5_wrap(out_mem_ctx, &unwrapped_out, TOK_ID_KRB_AP_REP);
 363                 }
 364                 SAFE_FREE(principal);
 365                 return nt_status;
 366         }
 367         case GENSEC_KRB5_DONE:
 368                 return NT_STATUS_OK;
 369         }
 370
 371         return NT_STATUS_INVALID_PARAMETER;
 372 }
 373
 374 static NTSTATUS gensec_krb5_session_key(struct gensec_security *gensec_security,
 375                                            DATA_BLOB *session_key)
 376 {
 377         struct gensec_krb5_state *gensec_krb5_state = gensec_security->private_data;
 378         krb5_context context = gensec_krb5_state->krb5_context;
 379         krb5_auth_context auth_context = gensec_krb5_state->krb5_auth_context;
 380         krb5_keyblock *skey;
 381         krb5_error_code err;
 382
 383         if (gensec_krb5_state->session_key.data) {
 384                 *session_key = gensec_krb5_state->session_key;
 385                 return NT_STATUS_OK;
 386         }
 387
 388         switch (gensec_security->gensec_role) {
 389         case GENSEC_CLIENT:
 390                 err = krb5_auth_con_getlocalsubkey(context, auth_context, &skey);
 391                 break;
 392         case GENSEC_SERVER:
 393                 err = krb5_auth_con_getremotesubkey(context, auth_context, &skey);
 394                 break;
 395         }
 396         if (err == 0 && skey != NULL) {
 397                 DEBUG(10, ("Got KRB5 session key of length %d\n",  KRB5_KEY_LENGTH(skey)));
 398                 gensec_krb5_state->session_key = data_blob_talloc(gensec_krb5_state->mem_ctx,
 399                                                 KRB5_KEY_DATA(skey), KRB5_KEY_LENGTH(skey));
 400                 *session_key = gensec_krb5_state->session_key;
 401                 dump_data_pw("KRB5 Session Key:\n", session_key->data, session_key->length);
 402
 403                 krb5_free_keyblock(context, skey);
 404                 return NT_STATUS_OK;
 405         } else {
 406                 DEBUG(10, ("KRB5 error getting session key %d\n", err));
 407                 return NT_STATUS_NO_USER_SESSION_KEY;
 408         }
 409 }
 410
 411
 412 static const struct gensec_security_ops gensec_krb5_security_ops = {
 413         .name           = "krb5",
 414         .auth_type      = DCERPC_AUTH_TYPE_KRB5,
 415         .oid            = OID_KERBEROS5,
 416         .client_start   = gensec_krb5_client_start,
 417         .server_start   = gensec_krb5_server_start,
 418         .update         = gensec_krb5_update,
 419         .session_key    = gensec_krb5_session_key,
 420         .end            = gensec_krb5_end
 421 };
 422
 423 static const struct gensec_security_ops gensec_ms_krb5_security_ops = {
 424         .name           = "ms_krb5",
 425         .auth_type      = DCERPC_AUTH_TYPE_KRB5,
 426         .oid            = OID_KERBEROS5_OLD,
 427         .client_start   = gensec_krb5_client_start,
 428         .server_start   = gensec_krb5_server_start,
 429         .update         = gensec_krb5_update,
 430         .session_key    = gensec_krb5_session_key,
 431         .end            = gensec_krb5_end
 432 };
 433
 434
 435 NTSTATUS gensec_krb5_init(void)
 436 {
 437         NTSTATUS ret;
 438         ret = register_backend("gensec", &gensec_krb5_security_ops);
 439         if (!NT_STATUS_IS_OK(ret)) {
 440                 DEBUG(0,("Failed to register '%s' gensec backend!\n",
 441                         gensec_krb5_security_ops.name));
 442                 return ret;
 443         }
 444
 445         ret = register_backend("gensec", &gensec_ms_krb5_security_ops);
 446         if (!NT_STATUS_IS_OK(ret)) {
 447                 DEBUG(0,("Failed to register '%s' gensec backend!\n",
 448                         gensec_krb5_security_ops.name));
 449                 return ret;
 450         }
 451
 452         return ret;
 453 }