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.h"
  25 #include "util_tdb.h"
  26
  27 /*******************************************************************
  28  Create the share security tdb.
  29  ********************************************************************/
  30
  31 static struct db_context *share_db; /* used for share security descriptors */
  32 #define SHARE_DATABASE_VERSION_V1 1
  33 #define SHARE_DATABASE_VERSION_V2 2 /* version id in little endian. */
  34 #define SHARE_DATABASE_VERSION_V3 3 /* canonicalized sharenames as lower case */
  35
  36 #define SHARE_SECURITY_DB_KEY_PREFIX_STR "SECDESC/"
  37 /* Map generic permissions to file object specific permissions */
  38
  39 extern const struct generic_mapping file_generic_mapping;
  40
  41 static int delete_fn(struct db_record *rec, void *priv)
  42 {
  43         rec->delete_rec(rec);
  44         return 0;
  45 }
  46
  47 /*****************************************************
  48  Looking for keys of the form: SHARE_SECURITY_DB_KEY_PREFIX_STR + "non lower case str".
  49  If we find one re-write it into a canonical case form.
  50 *****************************************************/
  51
  52 static int upgrade_v2_to_v3(struct db_record *rec, void *priv)
  53 {
  54         size_t prefix_len = strlen(SHARE_SECURITY_DB_KEY_PREFIX_STR);
  55         const char *servicename = NULL;
  56         char *c_servicename = NULL;
  57         char *newkey = NULL;
  58         bool *p_upgrade_ok = (bool *)priv;
  59         NTSTATUS status;
  60
  61         /* Is there space for a one character sharename ? */
  62         if (rec->key.dsize <= prefix_len+2) {
  63                 return 0;
  64         }
  65
  66         /* Does it start with the share key prefix ? */
  67         if (memcmp(rec->key.dptr, SHARE_SECURITY_DB_KEY_PREFIX_STR,
  68                         prefix_len) != 0) {
  69                 return 0;
  70         }
  71
  72         /* Is it a null terminated string as a key ? */
  73         if (rec->key.dptr[rec->key.dsize-1] != '\0') {
  74                 return 0;
  75         }
  76
  77         /* Bytes after the prefix are the sharename string. */
  78         servicename = (char *)&rec->key.dptr[prefix_len];
  79         c_servicename = canonicalize_servicename(talloc_tos(), servicename);
  80         if (!c_servicename) {
  81                 smb_panic("out of memory upgrading share security db from v2 -> v3");
  82         }
  83
  84         if (strcmp(servicename, c_servicename) == 0) {
  85                 /* Old and new names match. No canonicalization needed. */
  86                 TALLOC_FREE(c_servicename);
  87                 return 0;
  88         }
  89
  90         /* Oops. Need to canonicalize name, delete old then store new. */
  91         status = rec->delete_rec(rec);
  92         if (!NT_STATUS_IS_OK(status)) {
  93                 DEBUG(1, ("upgrade_v2_to_v3: Failed to delete secdesc for "
  94                           "%s: %s\n", rec->key.dptr, nt_errstr(status)));
  95                 TALLOC_FREE(c_servicename);
  96                 *p_upgrade_ok = false;
  97                 return -1;
  98         } else {
  99                 DEBUG(10, ("upgrade_v2_to_v3: deleted secdesc for "
 100                           "%s\n", rec->key.dptr ));
 101         }
 102
 103         if (!(newkey = talloc_asprintf(talloc_tos(),
 104                         SHARE_SECURITY_DB_KEY_PREFIX_STR "%s",
 105                         c_servicename))) {
 106                 smb_panic("out of memory upgrading share security db from v2 -> v3");
 107         }
 108
 109         status = dbwrap_store(share_db,
 110                                 string_term_tdb_data(newkey),
 111                                 rec->value,
 112                                 TDB_REPLACE);
 113
 114         if (!NT_STATUS_IS_OK(status)) {
 115                 DEBUG(1, ("upgrade_v2_to_v3: Failed to store secdesc for "
 116                           "%s: %s\n", c_servicename, nt_errstr(status)));
 117                 TALLOC_FREE(c_servicename);
 118                 TALLOC_FREE(newkey);
 119                 *p_upgrade_ok = false;
 120                 return -1;
 121         } else {
 122                 DEBUG(10, ("upgrade_v2_to_v3: stored secdesc for "
 123                           "%s\n", newkey ));
 124         }
 125
 126         TALLOC_FREE(newkey);
 127         TALLOC_FREE(c_servicename);
 128
 129         return 0;
 130 }
 131
 132 bool share_info_db_init(void)
 133 {
 134         const char *vstring = "INFO/version";
 135         int32 vers_id;
 136         int ret;
 137         bool upgrade_ok = true;
 138
 139         if (share_db != NULL) {
 140                 return True;
 141         }
 142
 143         share_db = db_open(NULL, state_path("share_info.tdb"), 0,
 144                                  TDB_DEFAULT, O_RDWR|O_CREAT, 0600);
 145         if (share_db == NULL) {
 146                 DEBUG(0,("Failed to open share info database %s (%s)\n",
 147                         state_path("share_info.tdb"), strerror(errno) ));
 148                 return False;
 149         }
 150
 151         vers_id = dbwrap_fetch_int32(share_db, vstring);
 152         if (vers_id == SHARE_DATABASE_VERSION_V3) {
 153                 return true;
 154         }
 155
 156         if (share_db->transaction_start(share_db) != 0) {
 157                 DEBUG(0, ("transaction_start failed\n"));
 158                 TALLOC_FREE(share_db);
 159                 return false;
 160         }
 161
 162         vers_id = dbwrap_fetch_int32(share_db, vstring);
 163         if (vers_id == SHARE_DATABASE_VERSION_V3) {
 164                 /*
 165                  * Race condition
 166                  */
 167                 if (share_db->transaction_cancel(share_db)) {
 168                         smb_panic("transaction_cancel failed");
 169                 }
 170                 return true;
 171         }
 172
 173         /* Move to at least V2. */
 174
 175         /* Cope with byte-reversed older versions of the db. */
 176         if ((vers_id == SHARE_DATABASE_VERSION_V1) || (IREV(vers_id) == SHARE_DATABASE_VERSION_V1)) {
 177                 /* Written on a bigendian machine with old fetch_int code. Save as le. */
 178
 179                 if (dbwrap_store_int32(share_db, vstring,
 180                                        SHARE_DATABASE_VERSION_V2) != 0) {
 181                         DEBUG(0, ("dbwrap_store_int32 failed\n"));
 182                         goto cancel;
 183                 }
 184                 vers_id = SHARE_DATABASE_VERSION_V2;
 185         }
 186
 187         if (vers_id != SHARE_DATABASE_VERSION_V2) {
 188                 ret = share_db->traverse(share_db, delete_fn, NULL);
 189                 if (ret < 0) {
 190                         DEBUG(0, ("traverse failed\n"));
 191                         goto cancel;
 192                 }
 193                 if (dbwrap_store_int32(share_db, vstring,
 194                                        SHARE_DATABASE_VERSION_V2) != 0) {
 195                         DEBUG(0, ("dbwrap_store_int32 failed\n"));
 196                         goto cancel;
 197                 }
 198         }
 199
 200         /* Finally upgrade to version 3, with canonicalized sharenames. */
 201
 202         ret = share_db->traverse(share_db, upgrade_v2_to_v3, &upgrade_ok);
 203         if (ret < 0 || upgrade_ok == false) {
 204                 DEBUG(0, ("traverse failed\n"));
 205                 goto cancel;
 206         }
 207         if (dbwrap_store_int32(share_db, vstring,
 208                                SHARE_DATABASE_VERSION_V3) != 0) {
 209                 DEBUG(0, ("dbwrap_store_int32 failed\n"));
 210                 goto cancel;
 211         }
 212
 213         if (share_db->transaction_commit(share_db) != 0) {
 214                 DEBUG(0, ("transaction_commit failed\n"));
 215                 return false;
 216         }
 217
 218         return true;
 219
 220  cancel:
 221         if (share_db->transaction_cancel(share_db)) {
 222                 smb_panic("transaction_cancel failed");
 223         }
 224
 225         return false;
 226 }
 227
 228 /*******************************************************************
 229  Fake up a Everyone, default access as a default.
 230  def_access is a GENERIC_XXX access mode.
 231  ********************************************************************/
 232
 233 struct security_descriptor *get_share_security_default( TALLOC_CTX *ctx, size_t *psize, uint32 def_access)
 234 {
 235         uint32_t sa;
 236         struct security_ace ace;
 237         struct security_acl *psa = NULL;
 238         struct security_descriptor *psd = NULL;
 239         uint32 spec_access = def_access;
 240
 241         se_map_generic(&spec_access, &file_generic_mapping);
 242
 243         sa = (def_access | spec_access );
 244         init_sec_ace(&ace, &global_sid_World, SEC_ACE_TYPE_ACCESS_ALLOWED, sa, 0);
 245
 246         if ((psa = make_sec_acl(ctx, NT4_ACL_REVISION, 1, &ace)) != NULL) {
 247                 psd = make_sec_desc(ctx, SECURITY_DESCRIPTOR_REVISION_1,
 248                                     SEC_DESC_SELF_RELATIVE, NULL, NULL, NULL,
 249                                     psa, psize);
 250         }
 251
 252         if (!psd) {
 253                 DEBUG(0,("get_share_security: Failed to make SEC_DESC.\n"));
 254                 return NULL;
 255         }
 256
 257         return psd;
 258 }
 259
 260 /*******************************************************************
 261  Pull a security descriptor from the share tdb.
 262  ********************************************************************/
 263
 264 struct security_descriptor *get_share_security( TALLOC_CTX *ctx, const char *servicename,
 265                               size_t *psize)
 266 {
 267         char *key;
 268         struct security_descriptor *psd = NULL;
 269         TDB_DATA data;
 270         char *c_servicename = canonicalize_servicename(talloc_tos(), servicename);
 271         NTSTATUS status;
 272
 273         if (!c_servicename) {
 274                 return NULL;
 275         }
 276
 277         if (!share_info_db_init()) {
 278                 TALLOC_FREE(c_servicename);
 279                 return NULL;
 280         }
 281
 282         if (!(key = talloc_asprintf(ctx, SHARE_SECURITY_DB_KEY_PREFIX_STR "%s", c_servicename))) {
 283                 TALLOC_FREE(c_servicename);
 284                 DEBUG(0, ("talloc_asprintf failed\n"));
 285                 return NULL;
 286         }
 287
 288         TALLOC_FREE(c_servicename);
 289
 290         data = dbwrap_fetch_bystring(share_db, talloc_tos(), key);
 291
 292         TALLOC_FREE(key);
 293
 294         if (data.dptr == NULL) {
 295                 return get_share_security_default(ctx, psize,
 296                                                   GENERIC_ALL_ACCESS);
 297         }
 298
 299         status = unmarshall_sec_desc(ctx, data.dptr, data.dsize, &psd);
 300
 301         TALLOC_FREE(data.dptr);
 302
 303         if (!NT_STATUS_IS_OK(status)) {
 304                 DEBUG(0, ("unmarshall_sec_desc failed: %s\n",
 305                           nt_errstr(status)));
 306                 return get_share_security_default(ctx, psize,
 307                                                   GENERIC_ALL_ACCESS);
 308         }
 309
 310         if (psd) {
 311                 *psize = ndr_size_security_descriptor(psd, 0);
 312         } else {
 313                 return get_share_security_default(ctx, psize,
 314                                                   GENERIC_ALL_ACCESS);
 315         }
 316
 317         return psd;
 318 }
 319
 320 /*******************************************************************
 321  Store a security descriptor in the share db.
 322  ********************************************************************/
 323
 324 bool set_share_security(const char *share_name, struct security_descriptor *psd)
 325 {
 326         TALLOC_CTX *frame = talloc_stackframe();
 327         char *key;
 328         bool ret = False;
 329         TDB_DATA blob;
 330         NTSTATUS status;
 331         char *c_share_name = canonicalize_servicename(frame, share_name);
 332
 333         if (!c_share_name) {
 334                 goto out;
 335         }
 336
 337         if (!share_info_db_init()) {
 338                 goto out;
 339         }
 340
 341         status = marshall_sec_desc(frame, psd, &blob.dptr, &blob.dsize);
 342
 343         if (!NT_STATUS_IS_OK(status)) {
 344                 DEBUG(0, ("marshall_sec_desc failed: %s\n",
 345                           nt_errstr(status)));
 346                 goto out;
 347         }
 348
 349         if (!(key = talloc_asprintf(frame, SHARE_SECURITY_DB_KEY_PREFIX_STR "%s", c_share_name))) {
 350                 DEBUG(0, ("talloc_asprintf failed\n"));
 351                 goto out;
 352         }
 353
 354         status = dbwrap_trans_store(share_db, string_term_tdb_data(key), blob,
 355                                     TDB_REPLACE);
 356         if (!NT_STATUS_IS_OK(status)) {
 357                 DEBUG(1, ("set_share_security: Failed to store secdesc for "
 358                           "%s: %s\n", share_name, nt_errstr(status)));
 359                 goto out;
 360         }
 361
 362         DEBUG(5,("set_share_security: stored secdesc for %s\n", share_name ));
 363         ret = True;
 364
 365  out:
 366         TALLOC_FREE(frame);
 367         return ret;
 368 }
 369
 370 /*******************************************************************
 371  Delete a security descriptor.
 372 ********************************************************************/
 373
 374 bool delete_share_security(const char *servicename)
 375 {
 376         TDB_DATA kbuf;
 377         char *key;
 378         NTSTATUS status;
 379         char *c_servicename = canonicalize_servicename(talloc_tos(), servicename);
 380
 381         if (!c_servicename) {
 382                 return NULL;
 383         }
 384
 385         if (!share_info_db_init()) {
 386                 TALLOC_FREE(c_servicename);
 387                 return False;
 388         }
 389
 390         if (!(key = talloc_asprintf(talloc_tos(), SHARE_SECURITY_DB_KEY_PREFIX_STR "%s",
 391                                     c_servicename))) {
 392                 TALLOC_FREE(c_servicename);
 393                 return False;
 394         }
 395         kbuf = string_term_tdb_data(key);
 396
 397         status = dbwrap_trans_delete(share_db, kbuf);
 398         if (!NT_STATUS_IS_OK(status)) {
 399                 DEBUG(0, ("delete_share_security: Failed to delete entry for "
 400                           "share %s: %s\n", c_servicename, nt_errstr(status)));
 401                 TALLOC_FREE(c_servicename);
 402                 return False;
 403         }
 404
 405         TALLOC_FREE(c_servicename);
 406         return True;
 407 }
 408
 409 /*******************************************************************
 410  Can this user access with share with the required permissions ?
 411 ********************************************************************/
 412
 413 bool share_access_check(const struct security_token *token,
 414                         const char *sharename,
 415                         uint32 desired_access,
 416                         uint32_t *pgranted)
 417 {
 418         uint32 granted;
 419         NTSTATUS status;
 420         struct security_descriptor *psd = NULL;
 421         size_t sd_size;
 422
 423         psd = get_share_security(talloc_tos(), sharename, &sd_size);
 424
 425         if (!psd) {
 426                 if (pgranted != NULL) {
 427                         *pgranted = desired_access;
 428                 }
 429                 return false;
 430         }
 431
 432         status = se_access_check(psd, token, desired_access, &granted);
 433
 434         TALLOC_FREE(psd);
 435
 436         if (pgranted != NULL) {
 437                 *pgranted = granted;
 438         }
 439
 440         return NT_STATUS_IS_OK(status);
 441 }
 442
 443 /***************************************************************************
 444  Parse the contents of an acl string from a usershare file.
 445 ***************************************************************************/
 446
 447 bool parse_usershare_acl(TALLOC_CTX *ctx, const char *acl_str, struct security_descriptor **ppsd)
 448 {
 449         size_t s_size = 0;
 450         const char *pacl = acl_str;
 451         int num_aces = 0;
 452         struct security_ace *ace_list = NULL;
 453         struct security_acl *psa = NULL;
 454         struct security_descriptor *psd = NULL;
 455         size_t sd_size = 0;
 456         int i;
 457
 458         *ppsd = NULL;
 459
 460         /* If the acl string is blank return "Everyone:R" */
 461         if (!*acl_str) {
 462                 struct security_descriptor *default_psd = get_share_security_default(ctx, &s_size, GENERIC_READ_ACCESS);
 463                 if (!default_psd) {
 464                         return False;
 465                 }
 466                 *ppsd = default_psd;
 467                 return True;
 468         }
 469
 470         num_aces = 1;
 471
 472         /* Add the number of ',' characters to get the number of aces. */
 473         num_aces += count_chars(pacl,',');
 474
 475         ace_list = talloc_array(ctx, struct security_ace, num_aces);
 476         if (!ace_list) {
 477                 return False;
 478         }
 479
 480         for (i = 0; i < num_aces; i++) {
 481                 uint32_t sa;
 482                 uint32 g_access;
 483                 uint32 s_access;
 484                 struct dom_sid sid;
 485                 char *sidstr;
 486                 enum security_ace_type type = SEC_ACE_TYPE_ACCESS_ALLOWED;
 487
 488                 if (!next_token_talloc(ctx, &pacl, &sidstr, ":")) {
 489                         DEBUG(0,("parse_usershare_acl: malformed usershare acl looking "
 490                                 "for ':' in string '%s'\n", pacl));
 491                         return False;
 492                 }
 493
 494                 if (!string_to_sid(&sid, sidstr)) {
 495                         DEBUG(0,("parse_usershare_acl: failed to convert %s to sid.\n",
 496                                 sidstr ));
 497                         return False;
 498                 }
 499
 500                 switch (*pacl) {
 501                         case 'F': /* Full Control, ie. R+W */
 502                         case 'f': /* Full Control, ie. R+W */
 503                                 s_access = g_access = GENERIC_ALL_ACCESS;
 504                                 break;
 505                         case 'R': /* Read only. */
 506                         case 'r': /* Read only. */
 507                                 s_access = g_access = GENERIC_READ_ACCESS;
 508                                 break;
 509                         case 'D': /* Deny all to this SID. */
 510                         case 'd': /* Deny all to this SID. */
 511                                 type = SEC_ACE_TYPE_ACCESS_DENIED;
 512                                 s_access = g_access = GENERIC_ALL_ACCESS;
 513                                 break;
 514                         default:
 515                                 DEBUG(0,("parse_usershare_acl: unknown acl type at %s.\n",
 516                                         pacl ));
 517                                 return False;
 518                 }
 519
 520                 pacl++;
 521                 if (*pacl && *pacl != ',') {
 522                         DEBUG(0,("parse_usershare_acl: bad acl string at %s.\n",
 523                                 pacl ));
 524                         return False;
 525                 }
 526                 pacl++; /* Go past any ',' */
 527
 528                 se_map_generic(&s_access, &file_generic_mapping);
 529                 sa = (g_access | s_access);
 530                 init_sec_ace(&ace_list[i], &sid, type, sa, 0);
 531         }
 532
 533         if ((psa = make_sec_acl(ctx, NT4_ACL_REVISION, num_aces, ace_list)) != NULL) {
 534                 psd = make_sec_desc(ctx, SECURITY_DESCRIPTOR_REVISION_1,
 535                                     SEC_DESC_SELF_RELATIVE, NULL, NULL, NULL,
 536                                     psa, &sd_size);
 537         }
 538
 539         if (!psd) {
 540                 DEBUG(0,("parse_usershare_acl: Failed to make SEC_DESC.\n"));
 541                 return False;
 542         }
 543
 544         *ppsd = psd;
 545         return True;
 546 }