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 "../libcli/security/security.h"
  22 #include "../librpc/gen_ndr/ndr_security.h"
  23 #include "dbwrap.h"
  24
  25 /*******************************************************************
  26  Create the share security tdb.
  27  ********************************************************************/
  28
  29 static struct db_context *share_db; /* used for share security descriptors */
  30 #define SHARE_DATABASE_VERSION_V1 1
  31 #define SHARE_DATABASE_VERSION_V2 2 /* version id in little endian. */
  32 #define SHARE_DATABASE_VERSION_V3 3 /* canonicalized sharenames as lower case */
  33
  34 #define SHARE_SECURITY_DB_KEY_PREFIX_STR "SECDESC/"
  35 /* Map generic permissions to file object specific permissions */
  36
  37 extern const struct generic_mapping file_generic_mapping;
  38
  39 static int delete_fn(struct db_record *rec, void *priv)
  40 {
  41         rec->delete_rec(rec);
  42         return 0;
  43 }
  44
  45 /*****************************************************
  46  Looking for keys of the form: SHARE_SECURITY_DB_KEY_PREFIX_STR + "non lower case str".
  47  If we find one re-write it into a canonical case form.
  48 *****************************************************/
  49
  50 static int upgrade_v2_to_v3(struct db_record *rec, void *priv)
  51 {
  52         size_t prefix_len = strlen(SHARE_SECURITY_DB_KEY_PREFIX_STR);
  53         const char *servicename = NULL;
  54         char *c_servicename = NULL;
  55         char *newkey = NULL;
  56         bool *p_upgrade_ok = (bool *)priv;
  57         NTSTATUS status;
  58
  59         /* Is there space for a one character sharename ? */
  60         if (rec->key.dsize <= prefix_len+2) {
  61                 return 0;
  62         }
  63
  64         /* Does it start with the share key prefix ? */
  65         if (memcmp(rec->key.dptr, SHARE_SECURITY_DB_KEY_PREFIX_STR,
  66                         prefix_len) != 0) {
  67                 return 0;
  68         }
  69
  70         /* Is it a null terminated string as a key ? */
  71         if (rec->key.dptr[rec->key.dsize-1] != '\0') {
  72                 return 0;
  73         }
  74
  75         /* Bytes after the prefix are the sharename string. */
  76         servicename = (char *)&rec->key.dptr[prefix_len];
  77         c_servicename = canonicalize_servicename(talloc_tos(), servicename);
  78         if (!c_servicename) {
  79                 smb_panic("out of memory upgrading share security db from v2 -> v3");
  80         }
  81
  82         if (strcmp(servicename, c_servicename) == 0) {
  83                 /* Old and new names match. No canonicalization needed. */
  84                 TALLOC_FREE(c_servicename);
  85                 return 0;
  86         }
  87
  88         /* Oops. Need to canonicalize name, delete old then store new. */
  89         status = rec->delete_rec(rec);
  90         if (!NT_STATUS_IS_OK(status)) {
  91                 DEBUG(1, ("upgrade_v2_to_v3: Failed to delete secdesc for "
  92                           "%s: %s\n", rec->key.dptr, nt_errstr(status)));
  93                 TALLOC_FREE(c_servicename);
  94                 *p_upgrade_ok = false;
  95                 return -1;
  96         } else {
  97                 DEBUG(10, ("upgrade_v2_to_v3: deleted secdesc for "
  98                           "%s\n", rec->key.dptr ));
  99         }
 100
 101         if (!(newkey = talloc_asprintf(talloc_tos(),
 102                         SHARE_SECURITY_DB_KEY_PREFIX_STR "%s",
 103                         c_servicename))) {
 104                 smb_panic("out of memory upgrading share security db from v2 -> v3");
 105         }
 106
 107         status = dbwrap_store(share_db,
 108                                 string_term_tdb_data(newkey),
 109                                 rec->value,
 110                                 TDB_REPLACE);
 111
 112         if (!NT_STATUS_IS_OK(status)) {
 113                 DEBUG(1, ("upgrade_v2_to_v3: Failed to store secdesc for "
 114                           "%s: %s\n", c_servicename, nt_errstr(status)));
 115                 TALLOC_FREE(c_servicename);
 116                 TALLOC_FREE(newkey);
 117                 *p_upgrade_ok = false;
 118                 return -1;
 119         } else {
 120                 DEBUG(10, ("upgrade_v2_to_v3: stored secdesc for "
 121                           "%s\n", newkey ));
 122         }
 123
 124         TALLOC_FREE(newkey);
 125         TALLOC_FREE(c_servicename);
 126
 127         return 0;
 128 }
 129
 130 bool share_info_db_init(void)
 131 {
 132         const char *vstring = "INFO/version";
 133         int32 vers_id;
 134         int ret;
 135         bool upgrade_ok = true;
 136
 137         if (share_db != NULL) {
 138                 return True;
 139         }
 140
 141         share_db = db_open(NULL, state_path("share_info.tdb"), 0,
 142                                  TDB_DEFAULT, O_RDWR|O_CREAT, 0600);
 143         if (share_db == NULL) {
 144                 DEBUG(0,("Failed to open share info database %s (%s)\n",
 145                         state_path("share_info.tdb"), strerror(errno) ));
 146                 return False;
 147         }
 148
 149         vers_id = dbwrap_fetch_int32(share_db, vstring);
 150         if (vers_id == SHARE_DATABASE_VERSION_V3) {
 151                 return true;
 152         }
 153
 154         if (share_db->transaction_start(share_db) != 0) {
 155                 DEBUG(0, ("transaction_start failed\n"));
 156                 TALLOC_FREE(share_db);
 157                 return false;
 158         }
 159
 160         vers_id = dbwrap_fetch_int32(share_db, vstring);
 161         if (vers_id == SHARE_DATABASE_VERSION_V3) {
 162                 /*
 163                  * Race condition
 164                  */
 165                 if (share_db->transaction_cancel(share_db)) {
 166                         smb_panic("transaction_cancel failed");
 167                 }
 168                 return true;
 169         }
 170
 171         /* Move to at least V2. */
 172
 173         /* Cope with byte-reversed older versions of the db. */
 174         if ((vers_id == SHARE_DATABASE_VERSION_V1) || (IREV(vers_id) == SHARE_DATABASE_VERSION_V1)) {
 175                 /* Written on a bigendian machine with old fetch_int code. Save as le. */
 176
 177                 if (dbwrap_store_int32(share_db, vstring,
 178                                        SHARE_DATABASE_VERSION_V2) != 0) {
 179                         DEBUG(0, ("dbwrap_store_int32 failed\n"));
 180                         goto cancel;
 181                 }
 182                 vers_id = SHARE_DATABASE_VERSION_V2;
 183         }
 184
 185         if (vers_id != SHARE_DATABASE_VERSION_V2) {
 186                 ret = share_db->traverse(share_db, delete_fn, NULL);
 187                 if (ret < 0) {
 188                         DEBUG(0, ("traverse failed\n"));
 189                         goto cancel;
 190                 }
 191                 if (dbwrap_store_int32(share_db, vstring,
 192                                        SHARE_DATABASE_VERSION_V2) != 0) {
 193                         DEBUG(0, ("dbwrap_store_int32 failed\n"));
 194                         goto cancel;
 195                 }
 196         }
 197
 198         /* Finally upgrade to version 3, with canonicalized sharenames. */
 199
 200         ret = share_db->traverse(share_db, upgrade_v2_to_v3, &upgrade_ok);
 201         if (ret < 0 || upgrade_ok == false) {
 202                 DEBUG(0, ("traverse failed\n"));
 203                 goto cancel;
 204         }
 205         if (dbwrap_store_int32(share_db, vstring,
 206                                SHARE_DATABASE_VERSION_V3) != 0) {
 207                 DEBUG(0, ("dbwrap_store_int32 failed\n"));
 208                 goto cancel;
 209         }
 210
 211         if (share_db->transaction_commit(share_db) != 0) {
 212                 DEBUG(0, ("transaction_commit failed\n"));
 213                 return false;
 214         }
 215
 216         return true;
 217
 218  cancel:
 219         if (share_db->transaction_cancel(share_db)) {
 220                 smb_panic("transaction_cancel failed");
 221         }
 222
 223         return false;
 224 }
 225
 226 /*******************************************************************
 227  Fake up a Everyone, default access as a default.
 228  def_access is a GENERIC_XXX access mode.
 229  ********************************************************************/
 230
 231 struct security_descriptor *get_share_security_default( TALLOC_CTX *ctx, size_t *psize, uint32 def_access)
 232 {
 233         uint32_t sa;
 234         struct security_ace ace;
 235         struct security_acl *psa = NULL;
 236         struct security_descriptor *psd = NULL;
 237         uint32 spec_access = def_access;
 238
 239         se_map_generic(&spec_access, &file_generic_mapping);
 240
 241         sa = (def_access | spec_access );
 242         init_sec_ace(&ace, &global_sid_World, SEC_ACE_TYPE_ACCESS_ALLOWED, sa, 0);
 243
 244         if ((psa = make_sec_acl(ctx, NT4_ACL_REVISION, 1, &ace)) != NULL) {
 245                 psd = make_sec_desc(ctx, SECURITY_DESCRIPTOR_REVISION_1,
 246                                     SEC_DESC_SELF_RELATIVE, NULL, NULL, NULL,
 247                                     psa, psize);
 248         }
 249
 250         if (!psd) {
 251                 DEBUG(0,("get_share_security: Failed to make SEC_DESC.\n"));
 252                 return NULL;
 253         }
 254
 255         return psd;
 256 }
 257
 258 /*******************************************************************
 259  Pull a security descriptor from the share tdb.
 260  ********************************************************************/
 261
 262 struct security_descriptor *get_share_security( TALLOC_CTX *ctx, const char *servicename,
 263                               size_t *psize)
 264 {
 265         char *key;
 266         struct security_descriptor *psd = NULL;
 267         TDB_DATA data;
 268         char *c_servicename = canonicalize_servicename(talloc_tos(), servicename);
 269         NTSTATUS status;
 270
 271         if (!c_servicename) {
 272                 return NULL;
 273         }
 274
 275         if (!share_info_db_init()) {
 276                 TALLOC_FREE(c_servicename);
 277                 return NULL;
 278         }
 279
 280         if (!(key = talloc_asprintf(ctx, SHARE_SECURITY_DB_KEY_PREFIX_STR "%s", c_servicename))) {
 281                 TALLOC_FREE(c_servicename);
 282                 DEBUG(0, ("talloc_asprintf failed\n"));
 283                 return NULL;
 284         }
 285
 286         TALLOC_FREE(c_servicename);
 287
 288         data = dbwrap_fetch_bystring(share_db, talloc_tos(), key);
 289
 290         TALLOC_FREE(key);
 291
 292         if (data.dptr == NULL) {
 293                 return get_share_security_default(ctx, psize,
 294                                                   GENERIC_ALL_ACCESS);
 295         }
 296
 297         status = unmarshall_sec_desc(ctx, data.dptr, data.dsize, &psd);
 298
 299         TALLOC_FREE(data.dptr);
 300
 301         if (!NT_STATUS_IS_OK(status)) {
 302                 DEBUG(0, ("unmarshall_sec_desc failed: %s\n",
 303                           nt_errstr(status)));
 304                 return get_share_security_default(ctx, psize,
 305                                                   GENERIC_ALL_ACCESS);
 306         }
 307
 308         if (psd) {
 309                 *psize = ndr_size_security_descriptor(psd, 0);
 310         } else {
 311                 return get_share_security_default(ctx, psize,
 312                                                   GENERIC_ALL_ACCESS);
 313         }
 314
 315         return psd;
 316 }
 317
 318 /*******************************************************************
 319  Store a security descriptor in the share db.
 320  ********************************************************************/
 321
 322 bool set_share_security(const char *share_name, struct security_descriptor *psd)
 323 {
 324         TALLOC_CTX *frame = talloc_stackframe();
 325         char *key;
 326         bool ret = False;
 327         TDB_DATA blob;
 328         NTSTATUS status;
 329         char *c_share_name = canonicalize_servicename(frame, share_name);
 330
 331         if (!c_share_name) {
 332                 goto out;
 333         }
 334
 335         if (!share_info_db_init()) {
 336                 goto out;
 337         }
 338
 339         status = marshall_sec_desc(frame, psd, &blob.dptr, &blob.dsize);
 340
 341         if (!NT_STATUS_IS_OK(status)) {
 342                 DEBUG(0, ("marshall_sec_desc failed: %s\n",
 343                           nt_errstr(status)));
 344                 goto out;
 345         }
 346
 347         if (!(key = talloc_asprintf(frame, SHARE_SECURITY_DB_KEY_PREFIX_STR "%s", c_share_name))) {
 348                 DEBUG(0, ("talloc_asprintf failed\n"));
 349                 goto out;
 350         }
 351
 352         status = dbwrap_trans_store(share_db, string_term_tdb_data(key), blob,
 353                                     TDB_REPLACE);
 354         if (!NT_STATUS_IS_OK(status)) {
 355                 DEBUG(1, ("set_share_security: Failed to store secdesc for "
 356                           "%s: %s\n", share_name, nt_errstr(status)));
 357                 goto out;
 358         }
 359
 360         DEBUG(5,("set_share_security: stored secdesc for %s\n", share_name ));
 361         ret = True;
 362
 363  out:
 364         TALLOC_FREE(frame);
 365         return ret;
 366 }
 367
 368 /*******************************************************************
 369  Delete a security descriptor.
 370 ********************************************************************/
 371
 372 bool delete_share_security(const char *servicename)
 373 {
 374         TDB_DATA kbuf;
 375         char *key;
 376         NTSTATUS status;
 377         char *c_servicename = canonicalize_servicename(talloc_tos(), servicename);
 378
 379         if (!c_servicename) {
 380                 return NULL;
 381         }
 382
 383         if (!share_info_db_init()) {
 384                 TALLOC_FREE(c_servicename);
 385                 return False;
 386         }
 387
 388         if (!(key = talloc_asprintf(talloc_tos(), SHARE_SECURITY_DB_KEY_PREFIX_STR "%s",
 389                                     c_servicename))) {
 390                 TALLOC_FREE(c_servicename);
 391                 return False;
 392         }
 393         kbuf = string_term_tdb_data(key);
 394
 395         status = dbwrap_trans_delete(share_db, kbuf);
 396         if (!NT_STATUS_IS_OK(status)) {
 397                 DEBUG(0, ("delete_share_security: Failed to delete entry for "
 398                           "share %s: %s\n", c_servicename, nt_errstr(status)));
 399                 TALLOC_FREE(c_servicename);
 400                 return False;
 401         }
 402
 403         TALLOC_FREE(c_servicename);
 404         return True;
 405 }
 406
 407 /*******************************************************************
 408  Can this user access with share with the required permissions ?
 409 ********************************************************************/
 410
 411 bool share_access_check(const struct security_token *token, const char *sharename,
 412                         uint32 desired_access)
 413 {
 414         uint32 granted;
 415         NTSTATUS status;
 416         struct security_descriptor *psd = NULL;
 417         size_t sd_size;
 418
 419         psd = get_share_security(talloc_tos(), sharename, &sd_size);
 420
 421         if (!psd) {
 422                 return True;
 423         }
 424
 425         status = se_access_check(psd, token, desired_access, &granted);
 426
 427         TALLOC_FREE(psd);
 428
 429         return NT_STATUS_IS_OK(status);
 430 }
 431
 432 /***************************************************************************
 433  Parse the contents of an acl string from a usershare file.
 434 ***************************************************************************/
 435
 436 bool parse_usershare_acl(TALLOC_CTX *ctx, const char *acl_str, struct security_descriptor **ppsd)
 437 {
 438         size_t s_size = 0;
 439         const char *pacl = acl_str;
 440         int num_aces = 0;
 441         struct security_ace *ace_list = NULL;
 442         struct security_acl *psa = NULL;
 443         struct security_descriptor *psd = NULL;
 444         size_t sd_size = 0;
 445         int i;
 446
 447         *ppsd = NULL;
 448
 449         /* If the acl string is blank return "Everyone:R" */
 450         if (!*acl_str) {
 451                 struct security_descriptor *default_psd = get_share_security_default(ctx, &s_size, GENERIC_READ_ACCESS);
 452                 if (!default_psd) {
 453                         return False;
 454                 }
 455                 *ppsd = default_psd;
 456                 return True;
 457         }
 458
 459         num_aces = 1;
 460
 461         /* Add the number of ',' characters to get the number of aces. */
 462         num_aces += count_chars(pacl,',');
 463
 464         ace_list = TALLOC_ARRAY(ctx, struct security_ace, num_aces);
 465         if (!ace_list) {
 466                 return False;
 467         }
 468
 469         for (i = 0; i < num_aces; i++) {
 470                 uint32_t sa;
 471                 uint32 g_access;
 472                 uint32 s_access;
 473                 struct dom_sid sid;
 474                 char *sidstr;
 475                 enum security_ace_type type = SEC_ACE_TYPE_ACCESS_ALLOWED;
 476
 477                 if (!next_token_talloc(ctx, &pacl, &sidstr, ":")) {
 478                         DEBUG(0,("parse_usershare_acl: malformed usershare acl looking "
 479                                 "for ':' in string '%s'\n", pacl));
 480                         return False;
 481                 }
 482
 483                 if (!string_to_sid(&sid, sidstr)) {
 484                         DEBUG(0,("parse_usershare_acl: failed to convert %s to sid.\n",
 485                                 sidstr ));
 486                         return False;
 487                 }
 488
 489                 switch (*pacl) {
 490                         case 'F': /* Full Control, ie. R+W */
 491                         case 'f': /* Full Control, ie. R+W */
 492                                 s_access = g_access = GENERIC_ALL_ACCESS;
 493                                 break;
 494                         case 'R': /* Read only. */
 495                         case 'r': /* Read only. */
 496                                 s_access = g_access = GENERIC_READ_ACCESS;
 497                                 break;
 498                         case 'D': /* Deny all to this SID. */
 499                         case 'd': /* Deny all to this SID. */
 500                                 type = SEC_ACE_TYPE_ACCESS_DENIED;
 501                                 s_access = g_access = GENERIC_ALL_ACCESS;
 502                                 break;
 503                         default:
 504                                 DEBUG(0,("parse_usershare_acl: unknown acl type at %s.\n",
 505                                         pacl ));
 506                                 return False;
 507                 }
 508
 509                 pacl++;
 510                 if (*pacl && *pacl != ',') {
 511                         DEBUG(0,("parse_usershare_acl: bad acl string at %s.\n",
 512                                 pacl ));
 513                         return False;
 514                 }
 515                 pacl++; /* Go past any ',' */
 516
 517                 se_map_generic(&s_access, &file_generic_mapping);
 518                 sa = (g_access | s_access);
 519                 init_sec_ace(&ace_list[i], &sid, type, sa, 0);
 520         }
 521
 522         if ((psa = make_sec_acl(ctx, NT4_ACL_REVISION, num_aces, ace_list)) != NULL) {
 523                 psd = make_sec_desc(ctx, SECURITY_DESCRIPTOR_REVISION_1,
 524                                     SEC_DESC_SELF_RELATIVE, NULL, NULL, NULL,
 525                                     psa, &sd_size);
 526         }
 527
 528         if (!psd) {
 529                 DEBUG(0,("parse_usershare_acl: Failed to make SEC_DESC.\n"));
 530                 return False;
 531         }
 532
 533         *ppsd = psd;
 534         return True;
 535 }