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         rec->delete_rec(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
  62         /* Is there space for a one character sharename ? */
  63         if (rec->key.dsize <= prefix_len+2) {
  64                 return 0;
  65         }
  66
  67         /* Does it start with the share key prefix ? */
  68         if (memcmp(rec->key.dptr, SHARE_SECURITY_DB_KEY_PREFIX_STR,
  69                         prefix_len) != 0) {
  70                 return 0;
  71         }
  72
  73         /* Is it a null terminated string as a key ? */
  74         if (rec->key.dptr[rec->key.dsize-1] != '\0') {
  75                 return 0;
  76         }
  77
  78         /* Bytes after the prefix are the sharename string. */
  79         servicename = (char *)&rec->key.dptr[prefix_len];
  80         c_servicename = canonicalize_servicename(talloc_tos(), servicename);
  81         if (!c_servicename) {
  82                 smb_panic("out of memory upgrading share security db from v2 -> v3");
  83         }
  84
  85         if (strcmp(servicename, c_servicename) == 0) {
  86                 /* Old and new names match. No canonicalization needed. */
  87                 TALLOC_FREE(c_servicename);
  88                 return 0;
  89         }
  90
  91         /* Oops. Need to canonicalize name, delete old then store new. */
  92         status = rec->delete_rec(rec);
  93         if (!NT_STATUS_IS_OK(status)) {
  94                 DEBUG(1, ("upgrade_v2_to_v3: Failed to delete secdesc for "
  95                           "%s: %s\n", rec->key.dptr, nt_errstr(status)));
  96                 TALLOC_FREE(c_servicename);
  97                 *p_upgrade_ok = false;
  98                 return -1;
  99         } else {
 100                 DEBUG(10, ("upgrade_v2_to_v3: deleted secdesc for "
 101                           "%s\n", rec->key.dptr ));
 102         }
 103
 104         if (!(newkey = talloc_asprintf(talloc_tos(),
 105                         SHARE_SECURITY_DB_KEY_PREFIX_STR "%s",
 106                         c_servicename))) {
 107                 smb_panic("out of memory upgrading share security db from v2 -> v3");
 108         }
 109
 110         status = dbwrap_store(share_db,
 111                                 string_term_tdb_data(newkey),
 112                                 rec->value,
 113                                 TDB_REPLACE);
 114
 115         if (!NT_STATUS_IS_OK(status)) {
 116                 DEBUG(1, ("upgrade_v2_to_v3: Failed to store secdesc for "
 117                           "%s: %s\n", c_servicename, nt_errstr(status)));
 118                 TALLOC_FREE(c_servicename);
 119                 TALLOC_FREE(newkey);
 120                 *p_upgrade_ok = false;
 121                 return -1;
 122         } else {
 123                 DEBUG(10, ("upgrade_v2_to_v3: stored secdesc for "
 124                           "%s\n", newkey ));
 125         }
 126
 127         TALLOC_FREE(newkey);
 128         TALLOC_FREE(c_servicename);
 129
 130         return 0;
 131 }
 132
 133 bool share_info_db_init(void)
 134 {
 135         const char *vstring = "INFO/version";
 136         int32 vers_id;
 137         int ret;
 138         bool upgrade_ok = true;
 139
 140         if (share_db != NULL) {
 141                 return True;
 142         }
 143
 144         share_db = db_open(NULL, state_path("share_info.tdb"), 0,
 145                                  TDB_DEFAULT, O_RDWR|O_CREAT, 0600);
 146         if (share_db == NULL) {
 147                 DEBUG(0,("Failed to open share info database %s (%s)\n",
 148                         state_path("share_info.tdb"), strerror(errno) ));
 149                 return False;
 150         }
 151
 152         vers_id = dbwrap_fetch_int32(share_db, vstring);
 153         if (vers_id == SHARE_DATABASE_VERSION_V3) {
 154                 return true;
 155         }
 156
 157         if (share_db->transaction_start(share_db) != 0) {
 158                 DEBUG(0, ("transaction_start failed\n"));
 159                 TALLOC_FREE(share_db);
 160                 return false;
 161         }
 162
 163         vers_id = dbwrap_fetch_int32(share_db, vstring);
 164         if (vers_id == SHARE_DATABASE_VERSION_V3) {
 165                 /*
 166                  * Race condition
 167                  */
 168                 if (share_db->transaction_cancel(share_db)) {
 169                         smb_panic("transaction_cancel failed");
 170                 }
 171                 return true;
 172         }
 173
 174         /* Move to at least V2. */
 175
 176         /* Cope with byte-reversed older versions of the db. */
 177         if ((vers_id == SHARE_DATABASE_VERSION_V1) || (IREV(vers_id) == SHARE_DATABASE_VERSION_V1)) {
 178                 /* Written on a bigendian machine with old fetch_int code. Save as le. */
 179
 180                 if (dbwrap_store_int32(share_db, vstring,
 181                                        SHARE_DATABASE_VERSION_V2) != 0) {
 182                         DEBUG(0, ("dbwrap_store_int32 failed\n"));
 183                         goto cancel;
 184                 }
 185                 vers_id = SHARE_DATABASE_VERSION_V2;
 186         }
 187
 188         if (vers_id != SHARE_DATABASE_VERSION_V2) {
 189                 ret = share_db->traverse(share_db, delete_fn, NULL);
 190                 if (ret < 0) {
 191                         DEBUG(0, ("traverse failed\n"));
 192                         goto cancel;
 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         }
 200
 201         /* Finally upgrade to version 3, with canonicalized sharenames. */
 202
 203         ret = share_db->traverse(share_db, upgrade_v2_to_v3, &upgrade_ok);
 204         if (ret < 0 || upgrade_ok == false) {
 205                 DEBUG(0, ("traverse failed\n"));
 206                 goto cancel;
 207         }
 208         if (dbwrap_store_int32(share_db, vstring,
 209                                SHARE_DATABASE_VERSION_V3) != 0) {
 210                 DEBUG(0, ("dbwrap_store_int32 failed\n"));
 211                 goto cancel;
 212         }
 213
 214         if (share_db->transaction_commit(share_db) != 0) {
 215                 DEBUG(0, ("transaction_commit failed\n"));
 216                 return false;
 217         }
 218
 219         return true;
 220
 221  cancel:
 222         if (share_db->transaction_cancel(share_db)) {
 223                 smb_panic("transaction_cancel failed");
 224         }
 225
 226         return false;
 227 }
 228
 229 /*******************************************************************
 230  Fake up a Everyone, default access as a default.
 231  def_access is a GENERIC_XXX access mode.
 232  ********************************************************************/
 233
 234 struct security_descriptor *get_share_security_default( TALLOC_CTX *ctx, size_t *psize, uint32 def_access)
 235 {
 236         uint32_t sa;
 237         struct security_ace ace;
 238         struct security_acl *psa = NULL;
 239         struct security_descriptor *psd = NULL;
 240         uint32 spec_access = def_access;
 241
 242         se_map_generic(&spec_access, &file_generic_mapping);
 243
 244         sa = (def_access | spec_access );
 245         init_sec_ace(&ace, &global_sid_World, SEC_ACE_TYPE_ACCESS_ALLOWED, sa, 0);
 246
 247         if ((psa = make_sec_acl(ctx, NT4_ACL_REVISION, 1, &ace)) != NULL) {
 248                 psd = make_sec_desc(ctx, SECURITY_DESCRIPTOR_REVISION_1,
 249                                     SEC_DESC_SELF_RELATIVE, NULL, NULL, NULL,
 250                                     psa, psize);
 251         }
 252
 253         if (!psd) {
 254                 DEBUG(0,("get_share_security: Failed to make SEC_DESC.\n"));
 255                 return NULL;
 256         }
 257
 258         return psd;
 259 }
 260
 261 /*******************************************************************
 262  Pull a security descriptor from the share tdb.
 263  ********************************************************************/
 264
 265 struct security_descriptor *get_share_security( TALLOC_CTX *ctx, const char *servicename,
 266                               size_t *psize)
 267 {
 268         char *key;
 269         struct security_descriptor *psd = NULL;
 270         TDB_DATA data;
 271         char *c_servicename = canonicalize_servicename(talloc_tos(), servicename);
 272         NTSTATUS status;
 273
 274         if (!c_servicename) {
 275                 return NULL;
 276         }
 277
 278         if (!share_info_db_init()) {
 279                 TALLOC_FREE(c_servicename);
 280                 return NULL;
 281         }
 282
 283         if (!(key = talloc_asprintf(ctx, SHARE_SECURITY_DB_KEY_PREFIX_STR "%s", c_servicename))) {
 284                 TALLOC_FREE(c_servicename);
 285                 DEBUG(0, ("talloc_asprintf failed\n"));
 286                 return NULL;
 287         }
 288
 289         TALLOC_FREE(c_servicename);
 290
 291         data = dbwrap_fetch_bystring(share_db, talloc_tos(), key);
 292
 293         TALLOC_FREE(key);
 294
 295         if (data.dptr == NULL) {
 296                 return get_share_security_default(ctx, psize,
 297                                                   SEC_RIGHTS_DIR_ALL);
 298         }
 299
 300         status = unmarshall_sec_desc(ctx, data.dptr, data.dsize, &psd);
 301
 302         TALLOC_FREE(data.dptr);
 303
 304         if (!NT_STATUS_IS_OK(status)) {
 305                 DEBUG(0, ("unmarshall_sec_desc failed: %s\n",
 306                           nt_errstr(status)));
 307                 return get_share_security_default(ctx, psize,
 308                                                   SEC_RIGHTS_DIR_ALL);
 309         }
 310
 311         if (psd) {
 312                 *psize = ndr_size_security_descriptor(psd, 0);
 313         } else {
 314                 return get_share_security_default(ctx, psize,
 315                                                   SEC_RIGHTS_DIR_ALL);
 316         }
 317
 318         return psd;
 319 }
 320
 321 /*******************************************************************
 322  Store a security descriptor in the share db.
 323  ********************************************************************/
 324
 325 bool set_share_security(const char *share_name, struct security_descriptor *psd)
 326 {
 327         TALLOC_CTX *frame = talloc_stackframe();
 328         char *key;
 329         bool ret = False;
 330         TDB_DATA blob;
 331         NTSTATUS status;
 332         char *c_share_name = canonicalize_servicename(frame, share_name);
 333
 334         if (!c_share_name) {
 335                 goto out;
 336         }
 337
 338         if (!share_info_db_init()) {
 339                 goto out;
 340         }
 341
 342         status = marshall_sec_desc(frame, psd, &blob.dptr, &blob.dsize);
 343
 344         if (!NT_STATUS_IS_OK(status)) {
 345                 DEBUG(0, ("marshall_sec_desc failed: %s\n",
 346                           nt_errstr(status)));
 347                 goto out;
 348         }
 349
 350         if (!(key = talloc_asprintf(frame, SHARE_SECURITY_DB_KEY_PREFIX_STR "%s", c_share_name))) {
 351                 DEBUG(0, ("talloc_asprintf failed\n"));
 352                 goto out;
 353         }
 354
 355         status = dbwrap_trans_store(share_db, string_term_tdb_data(key), blob,
 356                                     TDB_REPLACE);
 357         if (!NT_STATUS_IS_OK(status)) {
 358                 DEBUG(1, ("set_share_security: Failed to store secdesc for "
 359                           "%s: %s\n", share_name, nt_errstr(status)));
 360                 goto out;
 361         }
 362
 363         DEBUG(5,("set_share_security: stored secdesc for %s\n", share_name ));
 364         ret = True;
 365
 366  out:
 367         TALLOC_FREE(frame);
 368         return ret;
 369 }
 370
 371 /*******************************************************************
 372  Delete a security descriptor.
 373 ********************************************************************/
 374
 375 bool delete_share_security(const char *servicename)
 376 {
 377         TDB_DATA kbuf;
 378         char *key;
 379         NTSTATUS status;
 380         char *c_servicename = canonicalize_servicename(talloc_tos(), servicename);
 381
 382         if (!c_servicename) {
 383                 return NULL;
 384         }
 385
 386         if (!share_info_db_init()) {
 387                 TALLOC_FREE(c_servicename);
 388                 return False;
 389         }
 390
 391         if (!(key = talloc_asprintf(talloc_tos(), SHARE_SECURITY_DB_KEY_PREFIX_STR "%s",
 392                                     c_servicename))) {
 393                 TALLOC_FREE(c_servicename);
 394                 return False;
 395         }
 396         kbuf = string_term_tdb_data(key);
 397
 398         status = dbwrap_trans_delete(share_db, kbuf);
 399         if (!NT_STATUS_IS_OK(status)) {
 400                 DEBUG(0, ("delete_share_security: Failed to delete entry for "
 401                           "share %s: %s\n", c_servicename, nt_errstr(status)));
 402                 TALLOC_FREE(c_servicename);
 403                 return False;
 404         }
 405
 406         TALLOC_FREE(c_servicename);
 407         return True;
 408 }
 409
 410 /*******************************************************************
 411  Can this user access with share with the required permissions ?
 412 ********************************************************************/
 413
 414 bool share_access_check(const struct security_token *token,
 415                         const char *sharename,
 416                         uint32 desired_access,
 417                         uint32_t *pgranted)
 418 {
 419         uint32 granted;
 420         NTSTATUS status;
 421         struct security_descriptor *psd = NULL;
 422         size_t sd_size;
 423
 424         psd = get_share_security(talloc_tos(), sharename, &sd_size);
 425
 426         if (!psd) {
 427                 if (pgranted != NULL) {
 428                         *pgranted = desired_access;
 429                 }
 430                 return false;
 431         }
 432
 433         status = se_access_check(psd, token, desired_access, &granted);
 434
 435         TALLOC_FREE(psd);
 436
 437         if (pgranted != NULL) {
 438                 *pgranted = granted;
 439         }
 440
 441         return NT_STATUS_IS_OK(status);
 442 }
 443
 444 /***************************************************************************
 445  Parse the contents of an acl string from a usershare file.
 446 ***************************************************************************/
 447
 448 bool parse_usershare_acl(TALLOC_CTX *ctx, const char *acl_str, struct security_descriptor **ppsd)
 449 {
 450         size_t s_size = 0;
 451         const char *pacl = acl_str;
 452         int num_aces = 0;
 453         struct security_ace *ace_list = NULL;
 454         struct security_acl *psa = NULL;
 455         struct security_descriptor *psd = NULL;
 456         size_t sd_size = 0;
 457         int i;
 458
 459         *ppsd = NULL;
 460
 461         /* If the acl string is blank return "Everyone:R" */
 462         if (!*acl_str) {
 463                 struct security_descriptor *default_psd = get_share_security_default(ctx, &s_size, GENERIC_READ_ACCESS);
 464                 if (!default_psd) {
 465                         return False;
 466                 }
 467                 *ppsd = default_psd;
 468                 return True;
 469         }
 470
 471         num_aces = 1;
 472
 473         /* Add the number of ',' characters to get the number of aces. */
 474         num_aces += count_chars(pacl,',');
 475
 476         ace_list = talloc_array(ctx, struct security_ace, num_aces);
 477         if (!ace_list) {
 478                 return False;
 479         }
 480
 481         for (i = 0; i < num_aces; i++) {
 482                 uint32_t sa;
 483                 uint32 g_access;
 484                 uint32 s_access;
 485                 struct dom_sid sid;
 486                 char *sidstr;
 487                 enum security_ace_type type = SEC_ACE_TYPE_ACCESS_ALLOWED;
 488
 489                 if (!next_token_talloc(ctx, &pacl, &sidstr, ":")) {
 490                         DEBUG(0,("parse_usershare_acl: malformed usershare acl looking "
 491                                 "for ':' in string '%s'\n", pacl));
 492                         return False;
 493                 }
 494
 495                 if (!string_to_sid(&sid, sidstr)) {
 496                         DEBUG(0,("parse_usershare_acl: failed to convert %s to sid.\n",
 497                                 sidstr ));
 498                         return False;
 499                 }
 500
 501                 switch (*pacl) {
 502                         case 'F': /* Full Control, ie. R+W */
 503                         case 'f': /* Full Control, ie. R+W */
 504                                 s_access = g_access = GENERIC_ALL_ACCESS;
 505                                 break;
 506                         case 'R': /* Read only. */
 507                         case 'r': /* Read only. */
 508                                 s_access = g_access = GENERIC_READ_ACCESS;
 509                                 break;
 510                         case 'D': /* Deny all to this SID. */
 511                         case 'd': /* Deny all to this SID. */
 512                                 type = SEC_ACE_TYPE_ACCESS_DENIED;
 513                                 s_access = g_access = GENERIC_ALL_ACCESS;
 514                                 break;
 515                         default:
 516                                 DEBUG(0,("parse_usershare_acl: unknown acl type at %s.\n",
 517                                         pacl ));
 518                                 return False;
 519                 }
 520
 521                 pacl++;
 522                 if (*pacl && *pacl != ',') {
 523                         DEBUG(0,("parse_usershare_acl: bad acl string at %s.\n",
 524                                 pacl ));
 525                         return False;
 526                 }
 527                 pacl++; /* Go past any ',' */
 528
 529                 se_map_generic(&s_access, &file_generic_mapping);
 530                 sa = (g_access | s_access);
 531                 init_sec_ace(&ace_list[i], &sid, type, sa, 0);
 532         }
 533
 534         if ((psa = make_sec_acl(ctx, NT4_ACL_REVISION, num_aces, ace_list)) != NULL) {
 535                 psd = make_sec_desc(ctx, SECURITY_DESCRIPTOR_REVISION_1,
 536                                     SEC_DESC_SELF_RELATIVE, NULL, NULL, NULL,
 537                                     psa, &sd_size);
 538         }
 539
 540         if (!psd) {
 541                 DEBUG(0,("parse_usershare_acl: Failed to make SEC_DESC.\n"));
 542                 return False;
 543         }
 544
 545         *ppsd = psd;
 546         return True;
 547 }