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