source3/lib/sharesec.c

   1 /*
   2  *  Unix SMB/Netbios implementation.
   3  *  SEC_DESC handling functions
   4  *  Copyright (C) Jeremy R. Allison            1995-2003.
   5  *
   6  *  This program is free software; you can redistribute it and/or modify
   7  *  it under the terms of the GNU General Public License as published by
   8  *  the Free Software Foundation; either version 3 of the License, or
   9  *  (at your option) any later version.
  10  *
  11  *  This program is distributed in the hope that it will be useful,
  12  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  *  GNU General Public License for more details.
  15  *
  16  *  You should have received a copy of the GNU General Public License
  17  *  along with this program; if not, see <http://www.gnu.org/licenses/>.
  18  */
  19
  20 #include "includes.h"
  21 #include "system/filesys.h"
  22 #include "../libcli/security/security.h"
  23 #include "../librpc/gen_ndr/ndr_security.h"
  24 #include "dbwrap/dbwrap.h"
  25 #include "dbwrap/dbwrap_open.h"
  26 #include "util_tdb.h"
  27
  28 /*******************************************************************
  29  Create the share security tdb.
  30  ********************************************************************/
  31
  32 static struct db_context *share_db; /* used for share security descriptors */
  33 #define SHARE_DATABASE_VERSION_V1 1
  34 #define SHARE_DATABASE_VERSION_V2 2 /* version id in little endian. */
  35 #define SHARE_DATABASE_VERSION_V3 3 /* canonicalized sharenames as lower case */
  36
  37 #define SHARE_SECURITY_DB_KEY_PREFIX_STR "SECDESC/"
  38 /* Map generic permissions to file object specific permissions */
  39
  40 extern const struct generic_mapping file_generic_mapping;
  41
  42 static int delete_fn(struct db_record *rec, void *priv)
  43 {
  44         dbwrap_record_delete(rec);
  45         return 0;
  46 }
  47
  48 /*****************************************************
  49  Looking for keys of the form: SHARE_SECURITY_DB_KEY_PREFIX_STR + "non lower case str".
  50  If we find one re-write it into a canonical case form.
  51 *****************************************************/
  52
  53 static int upgrade_v2_to_v3(struct db_record *rec, void *priv)
  54 {
  55         size_t prefix_len = strlen(SHARE_SECURITY_DB_KEY_PREFIX_STR);
  56         const char *servicename = NULL;
  57         char *c_servicename = NULL;
  58         char *newkey = NULL;
  59         bool *p_upgrade_ok = (bool *)priv;
  60         NTSTATUS status;
  61         TDB_DATA key;
  62         TDB_DATA value;
  63
  64         key = dbwrap_record_get_key(rec);
  65
  66         /* Is there space for a one character sharename ? */
  67         if (key.dsize <= prefix_len+2) {
  68                 return 0;
  69         }
  70
  71         /* Does it start with the share key prefix ? */
  72         if (memcmp(key.dptr, SHARE_SECURITY_DB_KEY_PREFIX_STR,
  73                         prefix_len) != 0) {
  74                 return 0;
  75         }
  76
  77         /* Is it a null terminated string as a key ? */
  78         if (key.dptr[key.dsize-1] != '\0') {
  79                 return 0;
  80         }
  81
  82         /* Bytes after the prefix are the sharename string. */
  83         servicename = (char *)&key.dptr[prefix_len];
  84         c_servicename = canonicalize_servicename(talloc_tos(), servicename);
  85         if (!c_servicename) {
  86                 smb_panic("out of memory upgrading share security db from v2 -> v3");
  87         }
  88
  89         if (strcmp(servicename, c_servicename) == 0) {
  90                 /* Old and new names match. No canonicalization needed. */
  91                 TALLOC_FREE(c_servicename);
  92                 return 0;
  93         }
  94
  95         /* Oops. Need to canonicalize name, delete old then store new. */
  96         status = dbwrap_record_delete(rec);
  97         if (!NT_STATUS_IS_OK(status)) {
  98                 DEBUG(1, ("upgrade_v2_to_v3: Failed to delete secdesc for "
  99                           "%s: %s\n", (const char *)key.dptr,
 100                           nt_errstr(status)));
 101                 TALLOC_FREE(c_servicename);
 102                 *p_upgrade_ok = false;
 103                 return -1;
 104         } else {
 105                 DEBUG(10, ("upgrade_v2_to_v3: deleted secdesc for "
 106                           "%s\n", (const char *)key.dptr));
 107         }
 108
 109         if (!(newkey = talloc_asprintf(talloc_tos(),
 110                         SHARE_SECURITY_DB_KEY_PREFIX_STR "%s",
 111                         c_servicename))) {
 112                 smb_panic("out of memory upgrading share security db from v2 -> v3");
 113         }
 114
 115         value = dbwrap_record_get_value(rec);
 116         status = dbwrap_store(share_db,
 117                                 string_term_tdb_data(newkey),
 118                                 value,
 119                                 TDB_REPLACE);
 120
 121         if (!NT_STATUS_IS_OK(status)) {
 122                 DEBUG(1, ("upgrade_v2_to_v3: Failed to store secdesc for "
 123                           "%s: %s\n", c_servicename, nt_errstr(status)));
 124                 TALLOC_FREE(c_servicename);
 125                 TALLOC_FREE(newkey);
 126                 *p_upgrade_ok = false;
 127                 return -1;
 128         } else {
 129                 DEBUG(10, ("upgrade_v2_to_v3: stored secdesc for "
 130                           "%s\n", newkey ));
 131         }
 132
 133         TALLOC_FREE(newkey);
 134         TALLOC_FREE(c_servicename);
 135
 136         return 0;
 137 }
 138
 139 bool share_info_db_init(void)
 140 {
 141         const char *vstring = "INFO/version";
 142         int32 vers_id = 0;
 143         bool upgrade_ok = true;
 144         NTSTATUS status;
 145
 146         if (share_db != NULL) {
 147                 return True;
 148         }
 149
 150         share_db = db_open(NULL, state_path("share_info.tdb"), 0,
 151                            TDB_DEFAULT, O_RDWR|O_CREAT, 0600,
 152                            DBWRAP_LOCK_ORDER_1);
 153         if (share_db == NULL) {
 154                 DEBUG(0,("Failed to open share info database %s (%s)\n",
 155                         state_path("share_info.tdb"), strerror(errno) ));
 156                 return False;
 157         }
 158
 159         status = dbwrap_fetch_int32_bystring(share_db, vstring, &vers_id);
 160         if (!NT_STATUS_IS_OK(status)) {
 161                 vers_id = 0;
 162         }
 163
 164         if (vers_id == SHARE_DATABASE_VERSION_V3) {
 165                 return true;
 166         }
 167
 168         if (dbwrap_transaction_start(share_db) != 0) {
 169                 DEBUG(0, ("transaction_start failed\n"));
 170                 TALLOC_FREE(share_db);
 171                 return false;
 172         }
 173
 174         status = dbwrap_fetch_int32_bystring(share_db, vstring, &vers_id);
 175         if (!NT_STATUS_IS_OK(status)) {
 176                 vers_id = 0;
 177         }
 178
 179         if (vers_id == SHARE_DATABASE_VERSION_V3) {
 180                 /*
 181                  * Race condition
 182                  */
 183                 if (dbwrap_transaction_cancel(share_db)) {
 184                         smb_panic("transaction_cancel failed");
 185                 }
 186                 return true;
 187         }
 188
 189         /* Move to at least V2. */
 190
 191         /* Cope with byte-reversed older versions of the db. */
 192         if ((vers_id == SHARE_DATABASE_VERSION_V1) || (IREV(vers_id) == SHARE_DATABASE_VERSION_V1)) {
 193                 /* Written on a bigendian machine with old fetch_int code. Save as le. */
 194
 195                 status = dbwrap_store_int32_bystring(
 196                         share_db, vstring, SHARE_DATABASE_VERSION_V2);
 197                 if (!NT_STATUS_IS_OK(status)) {
 198                         DEBUG(0, ("dbwrap_store_int32 failed: %s\n",
 199                                   nt_errstr(status)));
 200                         goto cancel;
 201                 }
 202                 vers_id = SHARE_DATABASE_VERSION_V2;
 203         }
 204
 205         if (vers_id != SHARE_DATABASE_VERSION_V2) {
 206                 status = dbwrap_traverse(share_db, delete_fn, NULL, NULL);
 207                 if (!NT_STATUS_IS_OK(status)) {
 208                         DEBUG(0, ("traverse failed\n"));
 209                         goto cancel;
 210                 }
 211                 status = dbwrap_store_int32_bystring(
 212                         share_db, vstring, SHARE_DATABASE_VERSION_V2);
 213                 if (!NT_STATUS_IS_OK(status)) {
 214                         DEBUG(0, ("dbwrap_store_int32 failed: %s\n",
 215                                   nt_errstr(status)));
 216                         goto cancel;
 217                 }
 218         }
 219
 220         /* Finally upgrade to version 3, with canonicalized sharenames. */
 221
 222         status = dbwrap_traverse(share_db, upgrade_v2_to_v3, &upgrade_ok, NULL);
 223         if (!NT_STATUS_IS_OK(status) || upgrade_ok == false) {
 224                 DEBUG(0, ("traverse failed\n"));
 225                 goto cancel;
 226         }
 227         status = dbwrap_store_int32_bystring(
 228                 share_db, vstring, SHARE_DATABASE_VERSION_V3);
 229         if (!NT_STATUS_IS_OK(status)) {
 230                 DEBUG(0, ("dbwrap_store_int32 failed: %s\n",
 231                           nt_errstr(status)));
 232                 goto cancel;
 233         }
 234
 235         if (dbwrap_transaction_commit(share_db) != 0) {
 236                 DEBUG(0, ("transaction_commit failed\n"));
 237                 return false;
 238         }
 239
 240         return true;
 241
 242  cancel:
 243         if (dbwrap_transaction_cancel(share_db)) {
 244                 smb_panic("transaction_cancel failed");
 245         }
 246
 247         return false;
 248 }
 249
 250 /*******************************************************************
 251  Fake up a Everyone, default access as a default.
 252  def_access is a GENERIC_XXX access mode.
 253  ********************************************************************/
 254
 255 struct security_descriptor *get_share_security_default( TALLOC_CTX *ctx, size_t *psize, uint32 def_access)
 256 {
 257         uint32_t sa;
 258         struct security_ace ace;
 259         struct security_acl *psa = NULL;
 260         struct security_descriptor *psd = NULL;
 261         uint32 spec_access = def_access;
 262
 263         se_map_generic(&spec_access, &file_generic_mapping);
 264
 265         sa = (def_access | spec_access );
 266         init_sec_ace(&ace, &global_sid_World, SEC_ACE_TYPE_ACCESS_ALLOWED, sa, 0);
 267
 268         if ((psa = make_sec_acl(ctx, NT4_ACL_REVISION, 1, &ace)) != NULL) {
 269                 psd = make_sec_desc(ctx, SECURITY_DESCRIPTOR_REVISION_1,
 270                                     SEC_DESC_SELF_RELATIVE, NULL, NULL, NULL,
 271                                     psa, psize);
 272         }
 273
 274         if (!psd) {
 275                 DEBUG(0,("get_share_security: Failed to make SEC_DESC.\n"));
 276                 return NULL;
 277         }
 278
 279         return psd;
 280 }
 281
 282 /*******************************************************************
 283  Pull a security descriptor from the share tdb.
 284  ********************************************************************/
 285
 286 struct security_descriptor *get_share_security( TALLOC_CTX *ctx, const char *servicename,
 287                               size_t *psize)
 288 {
 289         char *key;
 290         struct security_descriptor *psd = NULL;
 291         TDB_DATA data;
 292         char *c_servicename = canonicalize_servicename(talloc_tos(), servicename);
 293         NTSTATUS status;
 294
 295         if (!c_servicename) {
 296                 return NULL;
 297         }
 298
 299         if (!share_info_db_init()) {
 300                 TALLOC_FREE(c_servicename);
 301                 return NULL;
 302         }
 303
 304         if (!(key = talloc_asprintf(ctx, SHARE_SECURITY_DB_KEY_PREFIX_STR "%s", c_servicename))) {
 305                 TALLOC_FREE(c_servicename);
 306                 DEBUG(0, ("talloc_asprintf failed\n"));
 307                 return NULL;
 308         }
 309
 310         TALLOC_FREE(c_servicename);
 311
 312         status = dbwrap_fetch_bystring(share_db, talloc_tos(), key, &data);
 313
 314         TALLOC_FREE(key);
 315
 316         if (!NT_STATUS_IS_OK(status)) {
 317                 return get_share_security_default(ctx, psize,
 318                                                   SEC_RIGHTS_DIR_ALL);
 319         }
 320
 321         status = unmarshall_sec_desc(ctx, data.dptr, data.dsize, &psd);
 322
 323         TALLOC_FREE(data.dptr);
 324
 325         if (!NT_STATUS_IS_OK(status)) {
 326                 DEBUG(0, ("unmarshall_sec_desc failed: %s\n",
 327                           nt_errstr(status)));
 328                 return get_share_security_default(ctx, psize,
 329                                                   SEC_RIGHTS_DIR_ALL);
 330         }
 331
 332         if (psd) {
 333                 *psize = ndr_size_security_descriptor(psd, 0);
 334         } else {
 335                 return get_share_security_default(ctx, psize,
 336                                                   SEC_RIGHTS_DIR_ALL);
 337         }
 338
 339         return psd;
 340 }
 341
 342 /*******************************************************************
 343  Store a security descriptor in the share db.
 344  ********************************************************************/
 345
 346 bool set_share_security(const char *share_name, struct security_descriptor *psd)
 347 {
 348         TALLOC_CTX *frame = talloc_stackframe();
 349         char *key;
 350         bool ret = False;
 351         TDB_DATA blob;
 352         NTSTATUS status;
 353         char *c_share_name = canonicalize_servicename(frame, share_name);
 354
 355         if (!c_share_name) {
 356                 goto out;
 357         }
 358
 359         if (!share_info_db_init()) {
 360                 goto out;
 361         }
 362
 363         status = marshall_sec_desc(frame, psd, &blob.dptr, &blob.dsize);
 364
 365         if (!NT_STATUS_IS_OK(status)) {
 366                 DEBUG(0, ("marshall_sec_desc failed: %s\n",
 367                           nt_errstr(status)));
 368                 goto out;
 369         }
 370
 371         if (!(key = talloc_asprintf(frame, SHARE_SECURITY_DB_KEY_PREFIX_STR "%s", c_share_name))) {
 372                 DEBUG(0, ("talloc_asprintf failed\n"));
 373                 goto out;
 374         }
 375
 376         status = dbwrap_trans_store(share_db, string_term_tdb_data(key), blob,
 377                                     TDB_REPLACE);
 378         if (!NT_STATUS_IS_OK(status)) {
 379                 DEBUG(1, ("set_share_security: Failed to store secdesc for "
 380                           "%s: %s\n", share_name, nt_errstr(status)));
 381                 goto out;
 382         }
 383
 384         DEBUG(5,("set_share_security: stored secdesc for %s\n", share_name ));
 385         ret = True;
 386
 387  out:
 388         TALLOC_FREE(frame);
 389         return ret;
 390 }
 391
 392 /*******************************************************************
 393  Delete a security descriptor.
 394 ********************************************************************/
 395
 396 bool delete_share_security(const char *servicename)
 397 {
 398         TDB_DATA kbuf;
 399         char *key;
 400         NTSTATUS status;
 401         char *c_servicename = canonicalize_servicename(talloc_tos(), servicename);
 402
 403         if (!c_servicename) {
 404                 return NULL;
 405         }
 406
 407         if (!share_info_db_init()) {
 408                 TALLOC_FREE(c_servicename);
 409                 return False;
 410         }
 411
 412         if (!(key = talloc_asprintf(talloc_tos(), SHARE_SECURITY_DB_KEY_PREFIX_STR "%s",
 413                                     c_servicename))) {
 414                 TALLOC_FREE(c_servicename);
 415                 return False;
 416         }
 417         kbuf = string_term_tdb_data(key);
 418
 419         status = dbwrap_trans_delete(share_db, kbuf);
 420         if (!NT_STATUS_IS_OK(status)) {
 421                 DEBUG(0, ("delete_share_security: Failed to delete entry for "
 422                           "share %s: %s\n", c_servicename, nt_errstr(status)));
 423                 TALLOC_FREE(c_servicename);
 424                 return False;
 425         }
 426
 427         TALLOC_FREE(c_servicename);
 428         return True;
 429 }
 430
 431 /*******************************************************************
 432  Can this user access with share with the required permissions ?
 433 ********************************************************************/
 434
 435 bool share_access_check(const struct security_token *token,
 436                         const char *sharename,
 437                         uint32 desired_access,
 438                         uint32_t *pgranted)
 439 {
 440         uint32 granted;
 441         NTSTATUS status;
 442         struct security_descriptor *psd = NULL;
 443         size_t sd_size;
 444
 445         psd = get_share_security(talloc_tos(), sharename, &sd_size);
 446
 447         if (!psd) {
 448                 if (pgranted != NULL) {
 449                         *pgranted = desired_access;
 450                 }
 451                 return false;
 452         }
 453
 454         status = se_file_access_check(psd, token, true, desired_access, &granted);
 455
 456         TALLOC_FREE(psd);
 457
 458         if (pgranted != NULL) {
 459                 *pgranted = granted;
 460         }
 461
 462         return NT_STATUS_IS_OK(status);
 463 }
 464
 465 /***************************************************************************
 466  Parse the contents of an acl string from a usershare file.
 467 ***************************************************************************/
 468
 469 bool parse_usershare_acl(TALLOC_CTX *ctx, const char *acl_str, struct security_descriptor **ppsd)
 470 {
 471         size_t s_size = 0;
 472         const char *pacl = acl_str;
 473         int num_aces = 0;
 474         struct security_ace *ace_list = NULL;
 475         struct security_acl *psa = NULL;
 476         struct security_descriptor *psd = NULL;
 477         size_t sd_size = 0;
 478         int i;
 479
 480         *ppsd = NULL;
 481
 482         /* If the acl string is blank return "Everyone:R" */
 483         if (!*acl_str) {
 484                 struct security_descriptor *default_psd = get_share_security_default(ctx, &s_size, GENERIC_READ_ACCESS);
 485                 if (!default_psd) {
 486                         return False;
 487                 }
 488                 *ppsd = default_psd;
 489                 return True;
 490         }
 491
 492         num_aces = 1;
 493
 494         /* Add the number of ',' characters to get the number of aces. */
 495         num_aces += count_chars(pacl,',');
 496
 497         ace_list = talloc_array(ctx, struct security_ace, num_aces);
 498         if (!ace_list) {
 499                 return False;
 500         }
 501
 502         for (i = 0; i < num_aces; i++) {
 503                 uint32_t sa;
 504                 uint32 g_access;
 505                 uint32 s_access;
 506                 struct dom_sid sid;
 507                 char *sidstr;
 508                 enum security_ace_type type = SEC_ACE_TYPE_ACCESS_ALLOWED;
 509
 510                 if (!next_token_talloc(ctx, &pacl, &sidstr, ":")) {
 511                         DEBUG(0,("parse_usershare_acl: malformed usershare acl looking "
 512                                 "for ':' in string '%s'\n", pacl));
 513                         return False;
 514                 }
 515
 516                 if (!string_to_sid(&sid, sidstr)) {
 517                         DEBUG(0,("parse_usershare_acl: failed to convert %s to sid.\n",
 518                                 sidstr ));
 519                         return False;
 520                 }
 521
 522                 switch (*pacl) {
 523                         case 'F': /* Full Control, ie. R+W */
 524                         case 'f': /* Full Control, ie. R+W */
 525                                 s_access = g_access = GENERIC_ALL_ACCESS;
 526                                 break;
 527                         case 'R': /* Read only. */
 528                         case 'r': /* Read only. */
 529                                 s_access = g_access = GENERIC_READ_ACCESS;
 530                                 break;
 531                         case 'D': /* Deny all to this SID. */
 532                         case 'd': /* Deny all to this SID. */
 533                                 type = SEC_ACE_TYPE_ACCESS_DENIED;
 534                                 s_access = g_access = GENERIC_ALL_ACCESS;
 535                                 break;
 536                         default:
 537                                 DEBUG(0,("parse_usershare_acl: unknown acl type at %s.\n",
 538                                         pacl ));
 539                                 return False;
 540                 }
 541
 542                 pacl++;
 543                 if (*pacl && *pacl != ',') {
 544                         DEBUG(0,("parse_usershare_acl: bad acl string at %s.\n",
 545                                 pacl ));
 546                         return False;
 547                 }
 548                 pacl++; /* Go past any ',' */
 549
 550                 se_map_generic(&s_access, &file_generic_mapping);
 551                 sa = (g_access | s_access);
 552                 init_sec_ace(&ace_list[i], &sid, type, sa, 0);
 553         }
 554
 555         if ((psa = make_sec_acl(ctx, NT4_ACL_REVISION, num_aces, ace_list)) != NULL) {
 556                 psd = make_sec_desc(ctx, SECURITY_DESCRIPTOR_REVISION_1,
 557                                     SEC_DESC_SELF_RELATIVE, NULL, NULL, NULL,
 558                                     psa, &sd_size);
 559         }
 560
 561         if (!psd) {
 562                 DEBUG(0,("parse_usershare_acl: Failed to make SEC_DESC.\n"));
 563                 return False;
 564         }
 565
 566         *ppsd = psd;
 567         return True;
 568 }