source3/libsmb/clispnego.c

   1 /*
   2    Unix SMB/CIFS implementation.
   3    simple kerberos5/SPNEGO routines
   4    Copyright (C) Andrew Tridgell 2001
   5    Copyright (C) Jim McDonough <jmcd@us.ibm.com> 2002
   6    Copyright (C) Luke Howard     2003
   7    Copyright (C) Jeremy Allison 2010
   8
   9    This program is free software; you can redistribute it and/or modify
  10    it under the terms of the GNU General Public License as published by
  11    the Free Software Foundation; either version 3 of the License, or
  12    (at your option) any later version.
  13
  14    This program is distributed in the hope that it will be useful,
  15    but WITHOUT ANY WARRANTY; without even the implied warranty of
  16    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17    GNU General Public License for more details.
  18
  19    You should have received a copy of the GNU General Public License
  20    along with this program.  If not, see <http://www.gnu.org/licenses/>.
  21 */
  22
  23 #include "includes.h"
  24 #include "../libcli/auth/spnego.h"
  25 #include "smb_krb5.h"
  26 #include "../lib/util/asn1.h"
  27
  28 /*
  29   generate a negTokenInit packet given a list of supported
  30   OIDs (the mechanisms) a blob, and a principal name string
  31 */
  32
  33 DATA_BLOB spnego_gen_negTokenInit(TALLOC_CTX *ctx,
  34                                   const char *OIDs[],
  35                                   DATA_BLOB *psecblob,
  36                                   const char *principal)
  37 {
  38         int i;
  39         ASN1_DATA *data;
  40         DATA_BLOB ret;
  41
  42         data = asn1_init(talloc_tos());
  43         if (data == NULL) {
  44                 return data_blob_null;
  45         }
  46
  47         asn1_push_tag(data,ASN1_APPLICATION(0));
  48         asn1_write_OID(data,OID_SPNEGO);
  49         asn1_push_tag(data,ASN1_CONTEXT(0));
  50         asn1_push_tag(data,ASN1_SEQUENCE(0));
  51
  52         asn1_push_tag(data,ASN1_CONTEXT(0));
  53         asn1_push_tag(data,ASN1_SEQUENCE(0));
  54         for (i=0; OIDs[i]; i++) {
  55                 asn1_write_OID(data,OIDs[i]);
  56         }
  57         asn1_pop_tag(data);
  58         asn1_pop_tag(data);
  59
  60         if (psecblob && psecblob->length && psecblob->data) {
  61                 asn1_push_tag(data, ASN1_CONTEXT(2));
  62                 asn1_write_OctetString(data,psecblob->data,
  63                         psecblob->length);
  64                 asn1_pop_tag(data);
  65         }
  66
  67         if (principal) {
  68                 asn1_push_tag(data, ASN1_CONTEXT(3));
  69                 asn1_push_tag(data, ASN1_SEQUENCE(0));
  70                 asn1_push_tag(data, ASN1_CONTEXT(0));
  71                 asn1_write_GeneralString(data,principal);
  72                 asn1_pop_tag(data);
  73                 asn1_pop_tag(data);
  74                 asn1_pop_tag(data);
  75         }
  76
  77         asn1_pop_tag(data);
  78         asn1_pop_tag(data);
  79
  80         asn1_pop_tag(data);
  81
  82         if (data->has_error) {
  83                 DEBUG(1,("Failed to build negTokenInit at offset %d\n", (int)data->ofs));
  84         }
  85
  86         ret = data_blob_talloc(ctx, data->data, data->length);
  87         asn1_free(data);
  88
  89         return ret;
  90 }
  91
  92 /*
  93   parse a negTokenInit packet giving a GUID, a list of supported
  94   OIDs (the mechanisms) and a principal name string
  95 */
  96 bool spnego_parse_negTokenInit(TALLOC_CTX *ctx,
  97                                DATA_BLOB blob,
  98                                char *OIDs[ASN1_MAX_OIDS],
  99                                char **principal,
 100                                DATA_BLOB *secblob)
 101 {
 102         int i;
 103         bool ret;
 104         ASN1_DATA *data;
 105
 106         data = asn1_init(talloc_tos());
 107         if (data == NULL) {
 108                 return false;
 109         }
 110
 111         asn1_load(data, blob);
 112
 113         asn1_start_tag(data,ASN1_APPLICATION(0));
 114
 115         asn1_check_OID(data,OID_SPNEGO);
 116
 117         /* negTokenInit  [0]  NegTokenInit */
 118         asn1_start_tag(data,ASN1_CONTEXT(0));
 119         asn1_start_tag(data,ASN1_SEQUENCE(0));
 120
 121         /* mechTypes [0] MechTypeList  OPTIONAL */
 122
 123         /* Not really optional, we depend on this to decide
 124          * what mechanisms we have to work with. */
 125
 126         asn1_start_tag(data,ASN1_CONTEXT(0));
 127         asn1_start_tag(data,ASN1_SEQUENCE(0));
 128         for (i=0; asn1_tag_remaining(data) > 0 && i < ASN1_MAX_OIDS-1; i++) {
 129                 if (!asn1_read_OID(data,ctx, &OIDs[i])) {
 130                         break;
 131                 }
 132                 if (data->has_error) {
 133                         break;
 134                 }
 135         }
 136         OIDs[i] = NULL;
 137         asn1_end_tag(data);
 138         asn1_end_tag(data);
 139
 140         if (principal) {
 141                 *principal = NULL;
 142         }
 143         if (secblob) {
 144                 *secblob = data_blob_null;
 145         }
 146
 147         /*
 148           Win7 + Live Sign-in Assistant attaches a mechToken
 149           ASN1_CONTEXT(2) to the negTokenInit packet
 150           which breaks our negotiation if we just assume
 151           the next tag is ASN1_CONTEXT(3).
 152         */
 153
 154         if (asn1_peek_tag(data, ASN1_CONTEXT(1))) {
 155                 uint8 flags;
 156
 157                 /* reqFlags [1] ContextFlags  OPTIONAL */
 158                 asn1_start_tag(data, ASN1_CONTEXT(1));
 159                 asn1_start_tag(data, ASN1_BIT_STRING);
 160                 while (asn1_tag_remaining(data) > 0) {
 161                         asn1_read_uint8(data, &flags);
 162                 }
 163                 asn1_end_tag(data);
 164                 asn1_end_tag(data);
 165         }
 166
 167         if (asn1_peek_tag(data, ASN1_CONTEXT(2))) {
 168                 DATA_BLOB sblob = data_blob_null;
 169                 /* mechToken [2] OCTET STRING  OPTIONAL */
 170                 asn1_start_tag(data, ASN1_CONTEXT(2));
 171                 asn1_read_OctetString(data, ctx, &sblob);
 172                 asn1_end_tag(data);
 173                 if (secblob) {
 174                         *secblob = sblob;
 175                 } else {
 176                         data_blob_free(&sblob);
 177                 }
 178         }
 179
 180         if (asn1_peek_tag(data, ASN1_CONTEXT(3))) {
 181                 char *princ = NULL;
 182                 /* mechListMIC [3] OCTET STRING  OPTIONAL */
 183                 asn1_start_tag(data, ASN1_CONTEXT(3));
 184                 asn1_start_tag(data, ASN1_SEQUENCE(0));
 185                 asn1_start_tag(data, ASN1_CONTEXT(0));
 186                 asn1_read_GeneralString(data, ctx, &princ);
 187                 asn1_end_tag(data);
 188                 asn1_end_tag(data);
 189                 asn1_end_tag(data);
 190                 if (principal) {
 191                         *principal = princ;
 192                 } else {
 193                         TALLOC_FREE(princ);
 194                 }
 195         }
 196
 197         asn1_end_tag(data);
 198         asn1_end_tag(data);
 199
 200         asn1_end_tag(data);
 201
 202         ret = !data->has_error;
 203         if (data->has_error) {
 204                 int j;
 205                 if (principal) {
 206                         TALLOC_FREE(*principal);
 207                 }
 208                 if (secblob) {
 209                         data_blob_free(secblob);
 210                 }
 211                 for(j = 0; j < i && j < ASN1_MAX_OIDS-1; j++) {
 212                         TALLOC_FREE(OIDs[j]);
 213                 }
 214         }
 215
 216         asn1_free(data);
 217         return ret;
 218 }
 219
 220 /*
 221   generate a krb5 GSS-API wrapper packet given a ticket
 222 */
 223 DATA_BLOB spnego_gen_krb5_wrap(TALLOC_CTX *ctx, const DATA_BLOB ticket, const uint8 tok_id[2])
 224 {
 225         ASN1_DATA *data;
 226         DATA_BLOB ret;
 227
 228         data = asn1_init(talloc_tos());
 229         if (data == NULL) {
 230                 return data_blob_null;
 231         }
 232
 233         asn1_push_tag(data, ASN1_APPLICATION(0));
 234         asn1_write_OID(data, OID_KERBEROS5);
 235
 236         asn1_write(data, tok_id, 2);
 237         asn1_write(data, ticket.data, ticket.length);
 238         asn1_pop_tag(data);
 239
 240         if (data->has_error) {
 241                 DEBUG(1,("Failed to build krb5 wrapper at offset %d\n", (int)data->ofs));
 242         }
 243
 244         ret = data_blob_talloc(ctx, data->data, data->length);
 245         asn1_free(data);
 246
 247         return ret;
 248 }
 249
 250 /*
 251    generate a SPNEGO krb5 negTokenInit packet, ready for a EXTENDED_SECURITY
 252    kerberos session setup
 253 */
 254 int spnego_gen_krb5_negTokenInit(TALLOC_CTX *ctx,
 255                             const char *principal, int time_offset,
 256                             DATA_BLOB *targ,
 257                             DATA_BLOB *session_key_krb5, uint32 extra_ap_opts,
 258                             const char *ccname, time_t *expire_time)
 259 {
 260         int retval;
 261         DATA_BLOB tkt, tkt_wrapped;
 262         const char *krb_mechs[] = {OID_KERBEROS5_OLD, OID_KERBEROS5, OID_NTLMSSP, NULL};
 263
 264         /* get a kerberos ticket for the service and extract the session key */
 265         retval = cli_krb5_get_ticket(ctx, principal, time_offset,
 266                                           &tkt, session_key_krb5,
 267                                           extra_ap_opts, ccname,
 268                                           expire_time, NULL);
 269         if (retval) {
 270                 return retval;
 271         }
 272
 273         /* wrap that up in a nice GSS-API wrapping */
 274         tkt_wrapped = spnego_gen_krb5_wrap(ctx, tkt, TOK_ID_KRB_AP_REQ);
 275
 276         /* and wrap that in a shiny SPNEGO wrapper */
 277         *targ = spnego_gen_negTokenInit(ctx, krb_mechs, &tkt_wrapped, NULL);
 278
 279         data_blob_free(&tkt_wrapped);
 280         data_blob_free(&tkt);
 281
 282         return retval;
 283 }
 284
 285
 286 /*
 287   parse a spnego NTLMSSP challenge packet giving two security blobs
 288 */
 289 bool spnego_parse_challenge(TALLOC_CTX *ctx, const DATA_BLOB blob,
 290                             DATA_BLOB *chal1, DATA_BLOB *chal2)
 291 {
 292         bool ret;
 293         ASN1_DATA *data;
 294
 295         ZERO_STRUCTP(chal1);
 296         ZERO_STRUCTP(chal2);
 297
 298         data = asn1_init(talloc_tos());
 299         if (data == NULL) {
 300                 return false;
 301         }
 302
 303         asn1_load(data, blob);
 304         asn1_start_tag(data,ASN1_CONTEXT(1));
 305         asn1_start_tag(data,ASN1_SEQUENCE(0));
 306
 307         asn1_start_tag(data,ASN1_CONTEXT(0));
 308         asn1_check_enumerated(data,1);
 309         asn1_end_tag(data);
 310
 311         asn1_start_tag(data,ASN1_CONTEXT(1));
 312         asn1_check_OID(data, OID_NTLMSSP);
 313         asn1_end_tag(data);
 314
 315         asn1_start_tag(data,ASN1_CONTEXT(2));
 316         asn1_read_OctetString(data, ctx, chal1);
 317         asn1_end_tag(data);
 318
 319         /* the second challenge is optional (XP doesn't send it) */
 320         if (asn1_tag_remaining(data)) {
 321                 asn1_start_tag(data,ASN1_CONTEXT(3));
 322                 asn1_read_OctetString(data, ctx, chal2);
 323                 asn1_end_tag(data);
 324         }
 325
 326         asn1_end_tag(data);
 327         asn1_end_tag(data);
 328
 329         ret = !data->has_error;
 330
 331         if (data->has_error) {
 332                 data_blob_free(chal1);
 333                 data_blob_free(chal2);
 334         }
 335
 336         asn1_free(data);
 337         return ret;
 338 }
 339
 340
 341 /*
 342  generate a SPNEGO auth packet. This will contain the encrypted passwords
 343 */
 344 DATA_BLOB spnego_gen_auth(TALLOC_CTX *ctx, DATA_BLOB blob)
 345 {
 346         ASN1_DATA *data;
 347         DATA_BLOB ret;
 348
 349         data = asn1_init(talloc_tos());
 350         if (data == NULL) {
 351                 return data_blob_null;
 352         }
 353
 354         asn1_push_tag(data, ASN1_CONTEXT(1));
 355         asn1_push_tag(data, ASN1_SEQUENCE(0));
 356         asn1_push_tag(data, ASN1_CONTEXT(2));
 357         asn1_write_OctetString(data,blob.data,blob.length);
 358         asn1_pop_tag(data);
 359         asn1_pop_tag(data);
 360         asn1_pop_tag(data);
 361
 362         ret = data_blob_talloc(ctx, data->data, data->length);
 363
 364         asn1_free(data);
 365
 366         return ret;
 367 }
 368
 369 /*
 370  parse a SPNEGO auth packet. This contains the encrypted passwords
 371 */
 372 bool spnego_parse_auth_response(TALLOC_CTX *ctx,
 373                                 DATA_BLOB blob, NTSTATUS nt_status,
 374                                 const char *mechOID,
 375                                 DATA_BLOB *auth)
 376 {
 377         ASN1_DATA *data;
 378         uint8 negResult;
 379
 380         if (NT_STATUS_IS_OK(nt_status)) {
 381                 negResult = SPNEGO_ACCEPT_COMPLETED;
 382         } else if (NT_STATUS_EQUAL(nt_status, NT_STATUS_MORE_PROCESSING_REQUIRED)) {
 383                 negResult = SPNEGO_ACCEPT_INCOMPLETE;
 384         } else {
 385                 negResult = SPNEGO_REJECT;
 386         }
 387
 388         data = asn1_init(talloc_tos());
 389         if (data == NULL) {
 390                 return false;
 391         }
 392
 393         asn1_load(data, blob);
 394         asn1_start_tag(data, ASN1_CONTEXT(1));
 395         asn1_start_tag(data, ASN1_SEQUENCE(0));
 396         asn1_start_tag(data, ASN1_CONTEXT(0));
 397         asn1_check_enumerated(data, negResult);
 398         asn1_end_tag(data);
 399
 400         *auth = data_blob_null;
 401
 402         if (asn1_tag_remaining(data)) {
 403                 asn1_start_tag(data,ASN1_CONTEXT(1));
 404                 asn1_check_OID(data, mechOID);
 405                 asn1_end_tag(data);
 406
 407                 if (asn1_tag_remaining(data)) {
 408                         asn1_start_tag(data,ASN1_CONTEXT(2));
 409                         asn1_read_OctetString(data, ctx, auth);
 410                         asn1_end_tag(data);
 411                 }
 412         } else if (negResult == SPNEGO_ACCEPT_INCOMPLETE) {
 413                 data->has_error = 1;
 414         }
 415
 416         /* Binding against Win2K DC returns a duplicate of the responseToken in
 417          * the optional mechListMIC field. This is a bug in Win2K. We ignore
 418          * this field if it exists. Win2K8 may return a proper mechListMIC at
 419          * which point we need to implement the integrity checking. */
 420         if (asn1_tag_remaining(data)) {
 421                 DATA_BLOB mechList = data_blob_null;
 422                 asn1_start_tag(data, ASN1_CONTEXT(3));
 423                 asn1_read_OctetString(data, ctx, &mechList);
 424                 asn1_end_tag(data);
 425                 data_blob_free(&mechList);
 426                 DEBUG(5,("spnego_parse_auth_response received mechListMIC, "
 427                     "ignoring.\n"));
 428         }
 429
 430         asn1_end_tag(data);
 431         asn1_end_tag(data);
 432
 433         if (data->has_error) {
 434                 DEBUG(3,("spnego_parse_auth_response failed at %d\n", (int)data->ofs));
 435                 asn1_free(data);
 436                 data_blob_free(auth);
 437                 return False;
 438         }
 439
 440         asn1_free(data);
 441         return True;
 442 }
 443