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         for (i = 0; i < ASN1_MAX_OIDS; i++) {
 107                 OIDs[i] = NULL;
 108         }
 109
 110         data = asn1_init(talloc_tos());
 111         if (data == NULL) {
 112                 return false;
 113         }
 114
 115         asn1_load(data, blob);
 116
 117         asn1_start_tag(data,ASN1_APPLICATION(0));
 118
 119         asn1_check_OID(data,OID_SPNEGO);
 120
 121         /* negTokenInit  [0]  NegTokenInit */
 122         asn1_start_tag(data,ASN1_CONTEXT(0));
 123         asn1_start_tag(data,ASN1_SEQUENCE(0));
 124
 125         /* mechTypes [0] MechTypeList  OPTIONAL */
 126
 127         /* Not really optional, we depend on this to decide
 128          * what mechanisms we have to work with. */
 129
 130         asn1_start_tag(data,ASN1_CONTEXT(0));
 131         asn1_start_tag(data,ASN1_SEQUENCE(0));
 132         for (i=0; asn1_tag_remaining(data) > 0 && i < ASN1_MAX_OIDS-1; i++) {
 133                 if (!asn1_read_OID(data,ctx, &OIDs[i])) {
 134                         break;
 135                 }
 136                 if (data->has_error) {
 137                         break;
 138                 }
 139         }
 140         OIDs[i] = NULL;
 141         asn1_end_tag(data);
 142         asn1_end_tag(data);
 143
 144         if (principal) {
 145                 *principal = NULL;
 146         }
 147         if (secblob) {
 148                 *secblob = data_blob_null;
 149         }
 150
 151         /*
 152           Win7 + Live Sign-in Assistant attaches a mechToken
 153           ASN1_CONTEXT(2) to the negTokenInit packet
 154           which breaks our negotiation if we just assume
 155           the next tag is ASN1_CONTEXT(3).
 156         */
 157
 158         if (asn1_peek_tag(data, ASN1_CONTEXT(1))) {
 159                 uint8 flags;
 160
 161                 /* reqFlags [1] ContextFlags  OPTIONAL */
 162                 asn1_start_tag(data, ASN1_CONTEXT(1));
 163                 asn1_start_tag(data, ASN1_BIT_STRING);
 164                 while (asn1_tag_remaining(data) > 0) {
 165                         asn1_read_uint8(data, &flags);
 166                 }
 167                 asn1_end_tag(data);
 168                 asn1_end_tag(data);
 169         }
 170
 171         if (asn1_peek_tag(data, ASN1_CONTEXT(2))) {
 172                 DATA_BLOB sblob = data_blob_null;
 173                 /* mechToken [2] OCTET STRING  OPTIONAL */
 174                 asn1_start_tag(data, ASN1_CONTEXT(2));
 175                 asn1_read_OctetString(data, ctx, &sblob);
 176                 asn1_end_tag(data);
 177                 if (secblob) {
 178                         *secblob = sblob;
 179                 } else {
 180                         data_blob_free(&sblob);
 181                 }
 182         }
 183
 184         if (asn1_peek_tag(data, ASN1_CONTEXT(3))) {
 185                 char *princ = NULL;
 186                 /* mechListMIC [3] OCTET STRING  OPTIONAL */
 187                 asn1_start_tag(data, ASN1_CONTEXT(3));
 188                 asn1_start_tag(data, ASN1_SEQUENCE(0));
 189                 asn1_start_tag(data, ASN1_CONTEXT(0));
 190                 asn1_read_GeneralString(data, ctx, &princ);
 191                 asn1_end_tag(data);
 192                 asn1_end_tag(data);
 193                 asn1_end_tag(data);
 194                 if (principal) {
 195                         *principal = princ;
 196                 } else {
 197                         TALLOC_FREE(princ);
 198                 }
 199         }
 200
 201         asn1_end_tag(data);
 202         asn1_end_tag(data);
 203
 204         asn1_end_tag(data);
 205
 206         ret = !data->has_error;
 207         if (data->has_error) {
 208                 int j;
 209                 if (principal) {
 210                         TALLOC_FREE(*principal);
 211                 }
 212                 if (secblob) {
 213                         data_blob_free(secblob);
 214                 }
 215                 for(j = 0; j < i && j < ASN1_MAX_OIDS-1; j++) {
 216                         TALLOC_FREE(OIDs[j]);
 217                 }
 218         }
 219
 220         asn1_free(data);
 221         return ret;
 222 }
 223
 224 /*
 225   generate a krb5 GSS-API wrapper packet given a ticket
 226 */
 227 DATA_BLOB spnego_gen_krb5_wrap(TALLOC_CTX *ctx, const DATA_BLOB ticket, const uint8 tok_id[2])
 228 {
 229         ASN1_DATA *data;
 230         DATA_BLOB ret;
 231
 232         data = asn1_init(talloc_tos());
 233         if (data == NULL) {
 234                 return data_blob_null;
 235         }
 236
 237         asn1_push_tag(data, ASN1_APPLICATION(0));
 238         asn1_write_OID(data, OID_KERBEROS5);
 239
 240         asn1_write(data, tok_id, 2);
 241         asn1_write(data, ticket.data, ticket.length);
 242         asn1_pop_tag(data);
 243
 244         if (data->has_error) {
 245                 DEBUG(1,("Failed to build krb5 wrapper at offset %d\n", (int)data->ofs));
 246         }
 247
 248         ret = data_blob_talloc(ctx, data->data, data->length);
 249         asn1_free(data);
 250
 251         return ret;
 252 }
 253
 254 /*
 255    generate a SPNEGO krb5 negTokenInit packet, ready for a EXTENDED_SECURITY
 256    kerberos session setup
 257 */
 258 int spnego_gen_krb5_negTokenInit(TALLOC_CTX *ctx,
 259                             const char *principal, int time_offset,
 260                             DATA_BLOB *targ,
 261                             DATA_BLOB *session_key_krb5, uint32 extra_ap_opts,
 262                             const char *ccname, time_t *expire_time)
 263 {
 264         int retval;
 265         DATA_BLOB tkt, tkt_wrapped;
 266         const char *krb_mechs[] = {OID_KERBEROS5_OLD, OID_KERBEROS5, OID_NTLMSSP, NULL};
 267
 268         /* get a kerberos ticket for the service and extract the session key */
 269         retval = cli_krb5_get_ticket(ctx, principal, time_offset,
 270                                           &tkt, session_key_krb5,
 271                                           extra_ap_opts, ccname,
 272                                           expire_time, NULL);
 273         if (retval) {
 274                 return retval;
 275         }
 276
 277         /* wrap that up in a nice GSS-API wrapping */
 278         tkt_wrapped = spnego_gen_krb5_wrap(ctx, tkt, TOK_ID_KRB_AP_REQ);
 279
 280         /* and wrap that in a shiny SPNEGO wrapper */
 281         *targ = spnego_gen_negTokenInit(ctx, krb_mechs, &tkt_wrapped, NULL);
 282
 283         data_blob_free(&tkt_wrapped);
 284         data_blob_free(&tkt);
 285
 286         return retval;
 287 }
 288
 289
 290 /*
 291   parse a spnego NTLMSSP challenge packet giving two security blobs
 292 */
 293 bool spnego_parse_challenge(TALLOC_CTX *ctx, const DATA_BLOB blob,
 294                             DATA_BLOB *chal1, DATA_BLOB *chal2)
 295 {
 296         bool ret;
 297         ASN1_DATA *data;
 298
 299         ZERO_STRUCTP(chal1);
 300         ZERO_STRUCTP(chal2);
 301
 302         data = asn1_init(talloc_tos());
 303         if (data == NULL) {
 304                 return false;
 305         }
 306
 307         asn1_load(data, blob);
 308         asn1_start_tag(data,ASN1_CONTEXT(1));
 309         asn1_start_tag(data,ASN1_SEQUENCE(0));
 310
 311         asn1_start_tag(data,ASN1_CONTEXT(0));
 312         asn1_check_enumerated(data,1);
 313         asn1_end_tag(data);
 314
 315         asn1_start_tag(data,ASN1_CONTEXT(1));
 316         asn1_check_OID(data, OID_NTLMSSP);
 317         asn1_end_tag(data);
 318
 319         asn1_start_tag(data,ASN1_CONTEXT(2));
 320         asn1_read_OctetString(data, ctx, chal1);
 321         asn1_end_tag(data);
 322
 323         /* the second challenge is optional (XP doesn't send it) */
 324         if (asn1_tag_remaining(data)) {
 325                 asn1_start_tag(data,ASN1_CONTEXT(3));
 326                 asn1_read_OctetString(data, ctx, chal2);
 327                 asn1_end_tag(data);
 328         }
 329
 330         asn1_end_tag(data);
 331         asn1_end_tag(data);
 332
 333         ret = !data->has_error;
 334
 335         if (data->has_error) {
 336                 data_blob_free(chal1);
 337                 data_blob_free(chal2);
 338         }
 339
 340         asn1_free(data);
 341         return ret;
 342 }
 343
 344
 345 /*
 346  generate a SPNEGO auth packet. This will contain the encrypted passwords
 347 */
 348 DATA_BLOB spnego_gen_auth(TALLOC_CTX *ctx, DATA_BLOB blob)
 349 {
 350         ASN1_DATA *data;
 351         DATA_BLOB ret;
 352
 353         data = asn1_init(talloc_tos());
 354         if (data == NULL) {
 355                 return data_blob_null;
 356         }
 357
 358         asn1_push_tag(data, ASN1_CONTEXT(1));
 359         asn1_push_tag(data, ASN1_SEQUENCE(0));
 360         asn1_push_tag(data, ASN1_CONTEXT(2));
 361         asn1_write_OctetString(data,blob.data,blob.length);
 362         asn1_pop_tag(data);
 363         asn1_pop_tag(data);
 364         asn1_pop_tag(data);
 365
 366         ret = data_blob_talloc(ctx, data->data, data->length);
 367
 368         asn1_free(data);
 369
 370         return ret;
 371 }
 372
 373 /*
 374  parse a SPNEGO auth packet. This contains the encrypted passwords
 375 */
 376 bool spnego_parse_auth_response(TALLOC_CTX *ctx,
 377                                 DATA_BLOB blob, NTSTATUS nt_status,
 378                                 const char *mechOID,
 379                                 DATA_BLOB *auth)
 380 {
 381         ASN1_DATA *data;
 382         uint8 negResult;
 383
 384         if (NT_STATUS_IS_OK(nt_status)) {
 385                 negResult = SPNEGO_ACCEPT_COMPLETED;
 386         } else if (NT_STATUS_EQUAL(nt_status, NT_STATUS_MORE_PROCESSING_REQUIRED)) {
 387                 negResult = SPNEGO_ACCEPT_INCOMPLETE;
 388         } else {
 389                 negResult = SPNEGO_REJECT;
 390         }
 391
 392         data = asn1_init(talloc_tos());
 393         if (data == NULL) {
 394                 return false;
 395         }
 396
 397         asn1_load(data, blob);
 398         asn1_start_tag(data, ASN1_CONTEXT(1));
 399         asn1_start_tag(data, ASN1_SEQUENCE(0));
 400         asn1_start_tag(data, ASN1_CONTEXT(0));
 401         asn1_check_enumerated(data, negResult);
 402         asn1_end_tag(data);
 403
 404         *auth = data_blob_null;
 405
 406         if (asn1_tag_remaining(data)) {
 407                 asn1_start_tag(data,ASN1_CONTEXT(1));
 408                 asn1_check_OID(data, mechOID);
 409                 asn1_end_tag(data);
 410
 411                 if (asn1_tag_remaining(data)) {
 412                         asn1_start_tag(data,ASN1_CONTEXT(2));
 413                         asn1_read_OctetString(data, ctx, auth);
 414                         asn1_end_tag(data);
 415                 }
 416         } else if (negResult == SPNEGO_ACCEPT_INCOMPLETE) {
 417                 data->has_error = 1;
 418         }
 419
 420         /* Binding against Win2K DC returns a duplicate of the responseToken in
 421          * the optional mechListMIC field. This is a bug in Win2K. We ignore
 422          * this field if it exists. Win2K8 may return a proper mechListMIC at
 423          * which point we need to implement the integrity checking. */
 424         if (asn1_tag_remaining(data)) {
 425                 DATA_BLOB mechList = data_blob_null;
 426                 asn1_start_tag(data, ASN1_CONTEXT(3));
 427                 asn1_read_OctetString(data, ctx, &mechList);
 428                 asn1_end_tag(data);
 429                 data_blob_free(&mechList);
 430                 DEBUG(5,("spnego_parse_auth_response received mechListMIC, "
 431                     "ignoring.\n"));
 432         }
 433
 434         asn1_end_tag(data);
 435         asn1_end_tag(data);
 436
 437         if (data->has_error) {
 438                 DEBUG(3,("spnego_parse_auth_response failed at %d\n", (int)data->ofs));
 439                 asn1_free(data);
 440                 data_blob_free(auth);
 441                 return False;
 442         }
 443
 444         asn1_free(data);
 445         return True;
 446 }
 447