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         if (share_db == NULL) {
 153                 DEBUG(0,("Failed to open share info database %s (%s)\n",
 154                         state_path("share_info.tdb"), strerror(errno) ));
 155                 return False;
 156         }
 157
 158         status = dbwrap_fetch_int32(share_db, vstring, &vers_id);
 159         if (!NT_STATUS_IS_OK(status)) {
 160                 vers_id = 0;
 161         }
 162
 163         if (vers_id == SHARE_DATABASE_VERSION_V3) {
 164                 return true;
 165         }
 166
 167         if (dbwrap_transaction_start(share_db) != 0) {
 168                 DEBUG(0, ("transaction_start failed\n"));
 169                 TALLOC_FREE(share_db);
 170                 return false;
 171         }
 172
 173         status = dbwrap_fetch_int32(share_db, vstring, &vers_id);
 174         if (!NT_STATUS_IS_OK(status)) {
 175                 vers_id = 0;
 176         }
 177
 178         if (vers_id == SHARE_DATABASE_VERSION_V3) {
 179                 /*
 180                  * Race condition
 181                  */
 182                 if (dbwrap_transaction_cancel(share_db)) {
 183                         smb_panic("transaction_cancel failed");
 184                 }
 185                 return true;
 186         }
 187
 188         /* Move to at least V2. */
 189
 190         /* Cope with byte-reversed older versions of the db. */
 191         if ((vers_id == SHARE_DATABASE_VERSION_V1) || (IREV(vers_id) == SHARE_DATABASE_VERSION_V1)) {
 192                 /* Written on a bigendian machine with old fetch_int code. Save as le. */
 193
 194                 if (dbwrap_store_int32(share_db, vstring,
 195                                        SHARE_DATABASE_VERSION_V2) != 0) {
 196                         DEBUG(0, ("dbwrap_store_int32 failed\n"));
 197                         goto cancel;
 198                 }
 199                 vers_id = SHARE_DATABASE_VERSION_V2;
 200         }
 201
 202         if (vers_id != SHARE_DATABASE_VERSION_V2) {
 203                 status = dbwrap_traverse(share_db, delete_fn, NULL, NULL);
 204                 if (!NT_STATUS_IS_OK(status)) {
 205                         DEBUG(0, ("traverse failed\n"));
 206                         goto cancel;
 207                 }
 208                 if (dbwrap_store_int32(share_db, vstring,
 209                                        SHARE_DATABASE_VERSION_V2) != 0) {
 210                         DEBUG(0, ("dbwrap_store_int32 failed\n"));
 211                         goto cancel;
 212                 }
 213         }
 214
 215         /* Finally upgrade to version 3, with canonicalized sharenames. */
 216
 217         status = dbwrap_traverse(share_db, upgrade_v2_to_v3, &upgrade_ok, NULL);
 218         if (!NT_STATUS_IS_OK(status) || upgrade_ok == false) {
 219                 DEBUG(0, ("traverse failed\n"));
 220                 goto cancel;
 221         }
 222         if (dbwrap_store_int32(share_db, vstring,
 223                                SHARE_DATABASE_VERSION_V3) != 0) {
 224                 DEBUG(0, ("dbwrap_store_int32 failed\n"));
 225                 goto cancel;
 226         }
 227
 228         if (dbwrap_transaction_commit(share_db) != 0) {
 229                 DEBUG(0, ("transaction_commit failed\n"));
 230                 return false;
 231         }
 232
 233         return true;
 234
 235  cancel:
 236         if (dbwrap_transaction_cancel(share_db)) {
 237                 smb_panic("transaction_cancel failed");
 238         }
 239
 240         return false;
 241 }
 242
 243 /*******************************************************************
 244  Fake up a Everyone, default access as a default.
 245  def_access is a GENERIC_XXX access mode.
 246  ********************************************************************/
 247
 248 struct security_descriptor *get_share_security_default( TALLOC_CTX *ctx, size_t *psize, uint32 def_access)
 249 {
 250         uint32_t sa;
 251         struct security_ace ace;
 252         struct security_acl *psa = NULL;
 253         struct security_descriptor *psd = NULL;
 254         uint32 spec_access = def_access;
 255
 256         se_map_generic(&spec_access, &file_generic_mapping);
 257
 258         sa = (def_access | spec_access );
 259         init_sec_ace(&ace, &global_sid_World, SEC_ACE_TYPE_ACCESS_ALLOWED, sa, 0);
 260
 261         if ((psa = make_sec_acl(ctx, NT4_ACL_REVISION, 1, &ace)) != NULL) {
 262                 psd = make_sec_desc(ctx, SECURITY_DESCRIPTOR_REVISION_1,
 263                                     SEC_DESC_SELF_RELATIVE, NULL, NULL, NULL,
 264                                     psa, psize);
 265         }
 266
 267         if (!psd) {
 268                 DEBUG(0,("get_share_security: Failed to make SEC_DESC.\n"));
 269                 return NULL;
 270         }
 271
 272         return psd;
 273 }
 274
 275 /*******************************************************************
 276  Pull a security descriptor from the share tdb.
 277  ********************************************************************/
 278
 279 struct security_descriptor *get_share_security( TALLOC_CTX *ctx, const char *servicename,
 280                               size_t *psize)
 281 {
 282         char *key;
 283         struct security_descriptor *psd = NULL;
 284         TDB_DATA data;
 285         char *c_servicename = canonicalize_servicename(talloc_tos(), servicename);
 286         NTSTATUS status;
 287
 288         if (!c_servicename) {
 289                 return NULL;
 290         }
 291
 292         if (!share_info_db_init()) {
 293                 TALLOC_FREE(c_servicename);
 294                 return NULL;
 295         }
 296
 297         if (!(key = talloc_asprintf(ctx, SHARE_SECURITY_DB_KEY_PREFIX_STR "%s", c_servicename))) {
 298                 TALLOC_FREE(c_servicename);
 299                 DEBUG(0, ("talloc_asprintf failed\n"));
 300                 return NULL;
 301         }
 302
 303         TALLOC_FREE(c_servicename);
 304
 305         status = dbwrap_fetch_bystring(share_db, talloc_tos(), key, &data);
 306
 307         TALLOC_FREE(key);
 308
 309         if (!NT_STATUS_IS_OK(status)) {
 310                 return get_share_security_default(ctx, psize,
 311                                                   SEC_RIGHTS_DIR_ALL);
 312         }
 313
 314         status = unmarshall_sec_desc(ctx, data.dptr, data.dsize, &psd);
 315
 316         TALLOC_FREE(data.dptr);
 317
 318         if (!NT_STATUS_IS_OK(status)) {
 319                 DEBUG(0, ("unmarshall_sec_desc failed: %s\n",
 320                           nt_errstr(status)));
 321                 return get_share_security_default(ctx, psize,
 322                                                   SEC_RIGHTS_DIR_ALL);
 323         }
 324
 325         if (psd) {
 326                 *psize = ndr_size_security_descriptor(psd, 0);
 327         } else {
 328                 return get_share_security_default(ctx, psize,
 329                                                   SEC_RIGHTS_DIR_ALL);
 330         }
 331
 332         return psd;
 333 }
 334
 335 /*******************************************************************
 336  Store a security descriptor in the share db.
 337  ********************************************************************/
 338
 339 bool set_share_security(const char *share_name, struct security_descriptor *psd)
 340 {
 341         TALLOC_CTX *frame = talloc_stackframe();
 342         char *key;
 343         bool ret = False;
 344         TDB_DATA blob;
 345         NTSTATUS status;
 346         char *c_share_name = canonicalize_servicename(frame, share_name);
 347
 348         if (!c_share_name) {
 349                 goto out;
 350         }
 351
 352         if (!share_info_db_init()) {
 353                 goto out;
 354         }
 355
 356         status = marshall_sec_desc(frame, psd, &blob.dptr, &blob.dsize);
 357
 358         if (!NT_STATUS_IS_OK(status)) {
 359                 DEBUG(0, ("marshall_sec_desc failed: %s\n",
 360                           nt_errstr(status)));
 361                 goto out;
 362         }
 363
 364         if (!(key = talloc_asprintf(frame, SHARE_SECURITY_DB_KEY_PREFIX_STR "%s", c_share_name))) {
 365                 DEBUG(0, ("talloc_asprintf failed\n"));
 366                 goto out;
 367         }
 368
 369         status = dbwrap_trans_store(share_db, string_term_tdb_data(key), blob,
 370                                     TDB_REPLACE);
 371         if (!NT_STATUS_IS_OK(status)) {
 372                 DEBUG(1, ("set_share_security: Failed to store secdesc for "
 373                           "%s: %s\n", share_name, nt_errstr(status)));
 374                 goto out;
 375         }
 376
 377         DEBUG(5,("set_share_security: stored secdesc for %s\n", share_name ));
 378         ret = True;
 379
 380  out:
 381         TALLOC_FREE(frame);
 382         return ret;
 383 }
 384
 385 /*******************************************************************
 386  Delete a security descriptor.
 387 ********************************************************************/
 388
 389 bool delete_share_security(const char *servicename)
 390 {
 391         TDB_DATA kbuf;
 392         char *key;
 393         NTSTATUS status;
 394         char *c_servicename = canonicalize_servicename(talloc_tos(), servicename);
 395
 396         if (!c_servicename) {
 397                 return NULL;
 398         }
 399
 400         if (!share_info_db_init()) {
 401                 TALLOC_FREE(c_servicename);
 402                 return False;
 403         }
 404
 405         if (!(key = talloc_asprintf(talloc_tos(), SHARE_SECURITY_DB_KEY_PREFIX_STR "%s",
 406                                     c_servicename))) {
 407                 TALLOC_FREE(c_servicename);
 408                 return False;
 409         }
 410         kbuf = string_term_tdb_data(key);
 411
 412         status = dbwrap_trans_delete(share_db, kbuf);
 413         if (!NT_STATUS_IS_OK(status)) {
 414                 DEBUG(0, ("delete_share_security: Failed to delete entry for "
 415                           "share %s: %s\n", c_servicename, nt_errstr(status)));
 416                 TALLOC_FREE(c_servicename);
 417                 return False;
 418         }
 419
 420         TALLOC_FREE(c_servicename);
 421         return True;
 422 }
 423
 424 /*******************************************************************
 425  Can this user access with share with the required permissions ?
 426 ********************************************************************/
 427
 428 bool share_access_check(const struct security_token *token,
 429                         const char *sharename,
 430                         uint32 desired_access,
 431                         uint32_t *pgranted)
 432 {
 433         uint32 granted;
 434         NTSTATUS status;
 435         struct security_descriptor *psd = NULL;
 436         size_t sd_size;
 437
 438         psd = get_share_security(talloc_tos(), sharename, &sd_size);
 439
 440         if (!psd) {
 441                 if (pgranted != NULL) {
 442                         *pgranted = desired_access;
 443                 }
 444                 return false;
 445         }
 446
 447         status = se_access_check(psd, token, desired_access, &granted);
 448
 449         TALLOC_FREE(psd);
 450
 451         if (pgranted != NULL) {
 452                 *pgranted = granted;
 453         }
 454
 455         return NT_STATUS_IS_OK(status);
 456 }
 457
 458 /***************************************************************************
 459  Parse the contents of an acl string from a usershare file.
 460 ***************************************************************************/
 461
 462 bool parse_usershare_acl(TALLOC_CTX *ctx, const char *acl_str, struct security_descriptor **ppsd)
 463 {
 464         size_t s_size = 0;
 465         const char *pacl = acl_str;
 466         int num_aces = 0;
 467         struct security_ace *ace_list = NULL;
 468         struct security_acl *psa = NULL;
 469         struct security_descriptor *psd = NULL;
 470         size_t sd_size = 0;
 471         int i;
 472
 473         *ppsd = NULL;
 474
 475         /* If the acl string is blank return "Everyone:R" */
 476         if (!*acl_str) {
 477                 struct security_descriptor *default_psd = get_share_security_default(ctx, &s_size, GENERIC_READ_ACCESS);
 478                 if (!default_psd) {
 479                         return False;
 480                 }
 481                 *ppsd = default_psd;
 482                 return True;
 483         }
 484
 485         num_aces = 1;
 486
 487         /* Add the number of ',' characters to get the number of aces. */
 488         num_aces += count_chars(pacl,',');
 489
 490         ace_list = talloc_array(ctx, struct security_ace, num_aces);
 491         if (!ace_list) {
 492                 return False;
 493         }
 494
 495         for (i = 0; i < num_aces; i++) {
 496                 uint32_t sa;
 497                 uint32 g_access;
 498                 uint32 s_access;
 499                 struct dom_sid sid;
 500                 char *sidstr;
 501                 enum security_ace_type type = SEC_ACE_TYPE_ACCESS_ALLOWED;
 502
 503                 if (!next_token_talloc(ctx, &pacl, &sidstr, ":")) {
 504                         DEBUG(0,("parse_usershare_acl: malformed usershare acl looking "
 505                                 "for ':' in string '%s'\n", pacl));
 506                         return False;
 507                 }
 508
 509                 if (!string_to_sid(&sid, sidstr)) {
 510                         DEBUG(0,("parse_usershare_acl: failed to convert %s to sid.\n",
 511                                 sidstr ));
 512                         return False;
 513                 }
 514
 515                 switch (*pacl) {
 516                         case 'F': /* Full Control, ie. R+W */
 517                         case 'f': /* Full Control, ie. R+W */
 518                                 s_access = g_access = GENERIC_ALL_ACCESS;
 519                                 break;
 520                         case 'R': /* Read only. */
 521                         case 'r': /* Read only. */
 522                                 s_access = g_access = GENERIC_READ_ACCESS;
 523                                 break;
 524                         case 'D': /* Deny all to this SID. */
 525                         case 'd': /* Deny all to this SID. */
 526                                 type = SEC_ACE_TYPE_ACCESS_DENIED;
 527                                 s_access = g_access = GENERIC_ALL_ACCESS;
 528                                 break;
 529                         default:
 530                                 DEBUG(0,("parse_usershare_acl: unknown acl type at %s.\n",
 531                                         pacl ));
 532                                 return False;
 533                 }
 534
 535                 pacl++;
 536                 if (*pacl && *pacl != ',') {
 537                         DEBUG(0,("parse_usershare_acl: bad acl string at %s.\n",
 538                                 pacl ));
 539                         return False;
 540                 }
 541                 pacl++; /* Go past any ',' */
 542
 543                 se_map_generic(&s_access, &file_generic_mapping);
 544                 sa = (g_access | s_access);
 545                 init_sec_ace(&ace_list[i], &sid, type, sa, 0);
 546         }
 547
 548         if ((psa = make_sec_acl(ctx, NT4_ACL_REVISION, num_aces, ace_list)) != NULL) {
 549                 psd = make_sec_desc(ctx, SECURITY_DESCRIPTOR_REVISION_1,
 550                                     SEC_DESC_SELF_RELATIVE, NULL, NULL, NULL,
 551                                     psa, &sd_size);
 552         }
 553
 554         if (!psd) {
 555                 DEBUG(0,("parse_usershare_acl: Failed to make SEC_DESC.\n"));
 556                 return False;
 557         }
 558
 559         *ppsd = psd;
 560         return True;
 561 }