libcli/auth/spnego_parse.c

   1 /*
   2    Unix SMB/CIFS implementation.
   3
   4    RFC2478 Compliant SPNEGO implementation
   5
   6    Copyright (C) Jim McDonough <jmcd@us.ibm.com>   2003
   7
   8    This program is free software; you can redistribute it and/or modify
   9    it under the terms of the GNU General Public License as published by
  10    the Free Software Foundation; either version 3 of the License, or
  11    (at your option) any later version.
  12
  13    This program is distributed in the hope that it will be useful,
  14    but WITHOUT ANY WARRANTY; without even the implied warranty of
  15    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16    GNU General Public License for more details.
  17
  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 "../lib/util/asn1.h"
  26
  27 static bool read_negTokenInit(struct asn1_data *asn1, TALLOC_CTX *mem_ctx,
  28                               struct spnego_negTokenInit *token)
  29 {
  30         ZERO_STRUCTP(token);
  31
  32         asn1_start_tag(asn1, ASN1_CONTEXT(0));
  33         asn1_start_tag(asn1, ASN1_SEQUENCE(0));
  34
  35         while (!asn1->has_error && 0 < asn1_tag_remaining(asn1)) {
  36                 int i;
  37                 uint8_t context;
  38                 if (!asn1_peek_uint8(asn1, &context)) {
  39                         asn1->has_error = true;
  40                         break;
  41                 }
  42
  43                 switch (context) {
  44                 /* Read mechTypes */
  45                 case ASN1_CONTEXT(0):
  46                         asn1_start_tag(asn1, ASN1_CONTEXT(0));
  47                         asn1_start_tag(asn1, ASN1_SEQUENCE(0));
  48
  49                         token->mechTypes = talloc(NULL, const char *);
  50                         for (i = 0; !asn1->has_error &&
  51                                      0 < asn1_tag_remaining(asn1); i++) {
  52                                 token->mechTypes = talloc_realloc(NULL,
  53                                                                   token->mechTypes,
  54                                                                   const char *, i+2);
  55                                 asn1_read_OID(asn1, token->mechTypes, token->mechTypes + i);
  56                         }
  57                         token->mechTypes[i] = NULL;
  58
  59                         asn1_end_tag(asn1);
  60                         asn1_end_tag(asn1);
  61                         break;
  62                 /* Read reqFlags */
  63                 case ASN1_CONTEXT(1):
  64                         asn1_start_tag(asn1, ASN1_CONTEXT(1));
  65                         asn1_read_BitString(asn1, mem_ctx, &token->reqFlags,
  66                                             &token->reqFlagsPadding);
  67                         asn1_end_tag(asn1);
  68                         break;
  69                 /* Read mechToken */
  70                 case ASN1_CONTEXT(2):
  71                         asn1_start_tag(asn1, ASN1_CONTEXT(2));
  72                         asn1_read_OctetString(asn1, mem_ctx, &token->mechToken);
  73                         asn1_end_tag(asn1);
  74                         break;
  75                 /* Read mecListMIC */
  76                 case ASN1_CONTEXT(3):
  77                 {
  78                         uint8_t type_peek;
  79                         asn1_start_tag(asn1, ASN1_CONTEXT(3));
  80                         if (!asn1_peek_uint8(asn1, &type_peek)) {
  81                                 asn1->has_error = true;
  82                                 break;
  83                         }
  84                         if (type_peek == ASN1_OCTET_STRING) {
  85                                 asn1_read_OctetString(asn1, mem_ctx,
  86                                                       &token->mechListMIC);
  87                         } else {
  88                                 /* RFC 2478 says we have an Octet String here,
  89                                    but W2k sends something different... */
  90                                 char *mechListMIC;
  91                                 asn1_start_tag(asn1, ASN1_SEQUENCE(0));
  92                                 asn1_start_tag(asn1, ASN1_CONTEXT(0));
  93                                 asn1_read_GeneralString(asn1, mem_ctx, &mechListMIC);
  94                                 asn1_end_tag(asn1);
  95                                 asn1_end_tag(asn1);
  96
  97                                 token->targetPrincipal = mechListMIC;
  98                         }
  99                         asn1_end_tag(asn1);
 100                         break;
 101                 }
 102                 default:
 103                         asn1->has_error = true;
 104                         break;
 105                 }
 106         }
 107
 108         asn1_end_tag(asn1);
 109         asn1_end_tag(asn1);
 110
 111         return !asn1->has_error;
 112 }
 113
 114 static bool write_negTokenInit(struct asn1_data *asn1, struct spnego_negTokenInit *token)
 115 {
 116         asn1_push_tag(asn1, ASN1_CONTEXT(0));
 117         asn1_push_tag(asn1, ASN1_SEQUENCE(0));
 118
 119         /* Write mechTypes */
 120         if (token->mechTypes && *token->mechTypes) {
 121                 int i;
 122
 123                 asn1_push_tag(asn1, ASN1_CONTEXT(0));
 124                 asn1_push_tag(asn1, ASN1_SEQUENCE(0));
 125                 for (i = 0; token->mechTypes[i]; i++) {
 126                         asn1_write_OID(asn1, token->mechTypes[i]);
 127                 }
 128                 asn1_pop_tag(asn1);
 129                 asn1_pop_tag(asn1);
 130         }
 131
 132         /* write reqFlags */
 133         if (token->reqFlags.length > 0) {
 134                 asn1_push_tag(asn1, ASN1_CONTEXT(1));
 135                 asn1_write_BitString(asn1, token->reqFlags.data,
 136                                      token->reqFlags.length,
 137                                      token->reqFlagsPadding);
 138                 asn1_pop_tag(asn1);
 139         }
 140
 141         /* write mechToken */
 142         if (token->mechToken.data) {
 143                 asn1_push_tag(asn1, ASN1_CONTEXT(2));
 144                 asn1_write_OctetString(asn1, token->mechToken.data,
 145                                        token->mechToken.length);
 146                 asn1_pop_tag(asn1);
 147         }
 148
 149         /* write mechListMIC */
 150         if (token->mechListMIC.data) {
 151                 asn1_push_tag(asn1, ASN1_CONTEXT(3));
 152 #if 0
 153                 /* This is what RFC 2478 says ... */
 154                 asn1_write_OctetString(asn1, token->mechListMIC.data,
 155                                        token->mechListMIC.length);
 156 #else
 157                 /* ... but unfortunately this is what Windows
 158                    sends/expects */
 159                 asn1_push_tag(asn1, ASN1_SEQUENCE(0));
 160                 asn1_push_tag(asn1, ASN1_CONTEXT(0));
 161                 asn1_push_tag(asn1, ASN1_GENERAL_STRING);
 162                 asn1_write(asn1, token->mechListMIC.data,
 163                            token->mechListMIC.length);
 164                 asn1_pop_tag(asn1);
 165                 asn1_pop_tag(asn1);
 166                 asn1_pop_tag(asn1);
 167 #endif
 168                 asn1_pop_tag(asn1);
 169         }
 170
 171         asn1_pop_tag(asn1);
 172         asn1_pop_tag(asn1);
 173
 174         return !asn1->has_error;
 175 }
 176
 177 static bool read_negTokenTarg(struct asn1_data *asn1, TALLOC_CTX *mem_ctx,
 178                               struct spnego_negTokenTarg *token)
 179 {
 180         ZERO_STRUCTP(token);
 181
 182         asn1_start_tag(asn1, ASN1_CONTEXT(1));
 183         asn1_start_tag(asn1, ASN1_SEQUENCE(0));
 184
 185         while (!asn1->has_error && 0 < asn1_tag_remaining(asn1)) {
 186                 uint8_t context;
 187                 if (!asn1_peek_uint8(asn1, &context)) {
 188                         asn1->has_error = true;
 189                         break;
 190                 }
 191
 192                 switch (context) {
 193                 case ASN1_CONTEXT(0):
 194                         asn1_start_tag(asn1, ASN1_CONTEXT(0));
 195                         asn1_start_tag(asn1, ASN1_ENUMERATED);
 196                         asn1_read_uint8(asn1, &token->negResult);
 197                         asn1_end_tag(asn1);
 198                         asn1_end_tag(asn1);
 199                         break;
 200                 case ASN1_CONTEXT(1):
 201                         asn1_start_tag(asn1, ASN1_CONTEXT(1));
 202                         asn1_read_OID(asn1, mem_ctx, &token->supportedMech);
 203                         asn1_end_tag(asn1);
 204                         break;
 205                 case ASN1_CONTEXT(2):
 206                         asn1_start_tag(asn1, ASN1_CONTEXT(2));
 207                         asn1_read_OctetString(asn1, mem_ctx, &token->responseToken);
 208                         asn1_end_tag(asn1);
 209                         break;
 210                 case ASN1_CONTEXT(3):
 211                         asn1_start_tag(asn1, ASN1_CONTEXT(3));
 212                         asn1_read_OctetString(asn1, mem_ctx, &token->mechListMIC);
 213                         asn1_end_tag(asn1);
 214                         break;
 215                 default:
 216                         asn1->has_error = true;
 217                         break;
 218                 }
 219         }
 220
 221         asn1_end_tag(asn1);
 222         asn1_end_tag(asn1);
 223
 224         return !asn1->has_error;
 225 }
 226
 227 static bool write_negTokenTarg(struct asn1_data *asn1, struct spnego_negTokenTarg *token)
 228 {
 229         asn1_push_tag(asn1, ASN1_CONTEXT(1));
 230         asn1_push_tag(asn1, ASN1_SEQUENCE(0));
 231
 232         if (token->negResult != SPNEGO_NONE_RESULT) {
 233                 asn1_push_tag(asn1, ASN1_CONTEXT(0));
 234                 asn1_write_enumerated(asn1, token->negResult);
 235                 asn1_pop_tag(asn1);
 236         }
 237
 238         if (token->supportedMech) {
 239                 asn1_push_tag(asn1, ASN1_CONTEXT(1));
 240                 asn1_write_OID(asn1, token->supportedMech);
 241                 asn1_pop_tag(asn1);
 242         }
 243
 244         if (token->responseToken.data) {
 245                 asn1_push_tag(asn1, ASN1_CONTEXT(2));
 246                 asn1_write_OctetString(asn1, token->responseToken.data,
 247                                        token->responseToken.length);
 248                 asn1_pop_tag(asn1);
 249         }
 250
 251         if (token->mechListMIC.data) {
 252                 asn1_push_tag(asn1, ASN1_CONTEXT(3));
 253                 asn1_write_OctetString(asn1, token->mechListMIC.data,
 254                                       token->mechListMIC.length);
 255                 asn1_pop_tag(asn1);
 256         }
 257
 258         asn1_pop_tag(asn1);
 259         asn1_pop_tag(asn1);
 260
 261         return !asn1->has_error;
 262 }
 263
 264 ssize_t spnego_read_data(TALLOC_CTX *mem_ctx, DATA_BLOB data, struct spnego_data *token)
 265 {
 266         struct asn1_data *asn1;
 267         ssize_t ret = -1;
 268         uint8_t context;
 269
 270         ZERO_STRUCTP(token);
 271
 272         if (data.length == 0) {
 273                 return ret;
 274         }
 275
 276         asn1 = asn1_init(mem_ctx);
 277         if (asn1 == NULL) {
 278                 return -1;
 279         }
 280
 281         asn1_load(asn1, data);
 282
 283         if (!asn1_peek_uint8(asn1, &context)) {
 284                 asn1->has_error = true;
 285         } else {
 286                 switch (context) {
 287                 case ASN1_APPLICATION(0):
 288                         asn1_start_tag(asn1, ASN1_APPLICATION(0));
 289                         asn1_check_OID(asn1, OID_SPNEGO);
 290                         if (read_negTokenInit(asn1, mem_ctx, &token->negTokenInit)) {
 291                                 token->type = SPNEGO_NEG_TOKEN_INIT;
 292                         }
 293                         asn1_end_tag(asn1);
 294                         break;
 295                 case ASN1_CONTEXT(1):
 296                         if (read_negTokenTarg(asn1, mem_ctx, &token->negTokenTarg)) {
 297                                 token->type = SPNEGO_NEG_TOKEN_TARG;
 298                         }
 299                         break;
 300                 default:
 301                         asn1->has_error = true;
 302                         break;
 303                 }
 304         }
 305
 306         if (!asn1->has_error) ret = asn1->ofs;
 307         asn1_free(asn1);
 308
 309         return ret;
 310 }
 311
 312 ssize_t spnego_write_data(TALLOC_CTX *mem_ctx, DATA_BLOB *blob, struct spnego_data *spnego)
 313 {
 314         struct asn1_data *asn1 = asn1_init(mem_ctx);
 315         ssize_t ret = -1;
 316
 317         if (asn1 == NULL) {
 318                 return -1;
 319         }
 320
 321         switch (spnego->type) {
 322         case SPNEGO_NEG_TOKEN_INIT:
 323                 asn1_push_tag(asn1, ASN1_APPLICATION(0));
 324                 asn1_write_OID(asn1, OID_SPNEGO);
 325                 write_negTokenInit(asn1, &spnego->negTokenInit);
 326                 asn1_pop_tag(asn1);
 327                 break;
 328         case SPNEGO_NEG_TOKEN_TARG:
 329                 write_negTokenTarg(asn1, &spnego->negTokenTarg);
 330                 break;
 331         default:
 332                 asn1->has_error = true;
 333                 break;
 334         }
 335
 336         if (!asn1->has_error) {
 337                 *blob = data_blob_talloc(mem_ctx, asn1->data, asn1->length);
 338                 ret = asn1->ofs;
 339         }
 340         asn1_free(asn1);
 341
 342         return ret;
 343 }
 344
 345 bool spnego_free_data(struct spnego_data *spnego)
 346 {
 347         bool ret = true;
 348
 349         if (!spnego) goto out;
 350
 351         switch(spnego->type) {
 352         case SPNEGO_NEG_TOKEN_INIT:
 353                 if (spnego->negTokenInit.mechTypes) {
 354                         talloc_free(spnego->negTokenInit.mechTypes);
 355                 }
 356                 data_blob_free(&spnego->negTokenInit.reqFlags);
 357                 data_blob_free(&spnego->negTokenInit.mechToken);
 358                 data_blob_free(&spnego->negTokenInit.mechListMIC);
 359                 talloc_free(spnego->negTokenInit.targetPrincipal);
 360                 break;
 361         case SPNEGO_NEG_TOKEN_TARG:
 362                 if (spnego->negTokenTarg.supportedMech) {
 363                         talloc_free(discard_const(spnego->negTokenTarg.supportedMech));
 364                 }
 365                 data_blob_free(&spnego->negTokenTarg.responseToken);
 366                 data_blob_free(&spnego->negTokenTarg.mechListMIC);
 367                 break;
 368         default:
 369                 ret = false;
 370                 break;
 371         }
 372         ZERO_STRUCTP(spnego);
 373 out:
 374         return ret;
 375 }
 376
 377 bool spnego_write_mech_types(TALLOC_CTX *mem_ctx,
 378                              const char **mech_types,
 379                              DATA_BLOB *blob)
 380 {
 381         struct asn1_data *asn1 = asn1_init(mem_ctx);
 382
 383         /* Write mechTypes */
 384         if (mech_types && *mech_types) {
 385                 int i;
 386
 387                 asn1_push_tag(asn1, ASN1_SEQUENCE(0));
 388                 for (i = 0; mech_types[i]; i++) {
 389                         asn1_write_OID(asn1, mech_types[i]);
 390                 }
 391                 asn1_pop_tag(asn1);
 392         }
 393
 394         if (asn1->has_error) {
 395                 asn1_free(asn1);
 396                 return false;
 397         }
 398
 399         *blob = data_blob_talloc(mem_ctx, asn1->data, asn1->length);
 400         if (blob->length != asn1->length) {
 401                 asn1_free(asn1);
 402                 return false;
 403         }
 404
 405         asn1_free(asn1);
 406
 407         return true;
 408 }