source/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
  22 /*******************************************************************
  23  Create the share security tdb.
  24  ********************************************************************/
  25
  26 static struct db_context *share_db; /* used for share security descriptors */
  27 #define SHARE_DATABASE_VERSION_V1 1
  28 #define SHARE_DATABASE_VERSION_V2 2 /* version id in little endian. */
  29
  30 /* Map generic permissions to file object specific permissions */
  31
  32 static const struct generic_mapping file_generic_mapping = {
  33         FILE_GENERIC_READ,
  34         FILE_GENERIC_WRITE,
  35         FILE_GENERIC_EXECUTE,
  36         FILE_GENERIC_ALL
  37 };
  38
  39 static int delete_fn(struct db_record *rec, void *priv)
  40 {
  41         rec->delete_rec(rec);
  42         return 0;
  43 }
  44
  45 static bool share_info_db_init(void)
  46 {
  47         const char *vstring = "INFO/version";
  48         int32 vers_id;
  49
  50         if (share_db != NULL) {
  51                 return True;
  52         }
  53
  54         share_db = db_open(NULL, state_path("share_info.tdb"), 0,
  55                                  TDB_DEFAULT, O_RDWR|O_CREAT, 0600);
  56         if (share_db == NULL) {
  57                 DEBUG(0,("Failed to open share info database %s (%s)\n",
  58                         state_path("share_info.tdb"), strerror(errno) ));
  59                 return False;
  60         }
  61
  62         vers_id = dbwrap_fetch_int32(share_db, vstring);
  63         if (vers_id == SHARE_DATABASE_VERSION_V2) {
  64                 return true;
  65         }
  66
  67         if (share_db->transaction_start(share_db) != 0) {
  68                 DEBUG(0, ("transaction_start failed\n"));
  69                 TALLOC_FREE(share_db);
  70                 return false;
  71         }
  72
  73         vers_id = dbwrap_fetch_int32(share_db, vstring);
  74         if (vers_id == SHARE_DATABASE_VERSION_V2) {
  75                 /*
  76                  * Race condition
  77                  */
  78                 if (share_db->transaction_cancel(share_db)) {
  79                         smb_panic("transaction_cancel failed");
  80                 }
  81                 return true;
  82         }
  83
  84         /* Cope with byte-reversed older versions of the db. */
  85         if ((vers_id == SHARE_DATABASE_VERSION_V1) || (IREV(vers_id) == SHARE_DATABASE_VERSION_V1)) {
  86                 /* Written on a bigendian machine with old fetch_int code. Save as le. */
  87
  88                 if (dbwrap_store_int32(share_db, vstring,
  89                                        SHARE_DATABASE_VERSION_V2) != 0) {
  90                         DEBUG(0, ("dbwrap_store_int32 failed\n"));
  91                         goto cancel;
  92                 }
  93                 vers_id = SHARE_DATABASE_VERSION_V2;
  94         }
  95
  96         if (vers_id != SHARE_DATABASE_VERSION_V2) {
  97                 int ret;
  98                 ret = share_db->traverse(share_db, delete_fn, NULL);
  99                 if (ret < 0) {
 100                         DEBUG(0, ("traverse failed\n"));
 101                         goto cancel;
 102                 }
 103                 if (dbwrap_store_int32(share_db, vstring,
 104                                        SHARE_DATABASE_VERSION_V2) != 0) {
 105                         DEBUG(0, ("dbwrap_store_int32 failed\n"));
 106                         goto cancel;
 107                 }
 108         }
 109
 110         if (share_db->transaction_commit(share_db) != 0) {
 111                 DEBUG(0, ("transaction_commit failed\n"));
 112                 return false;
 113         }
 114
 115         return true;
 116
 117  cancel:
 118         if (share_db->transaction_cancel(share_db)) {
 119                 smb_panic("transaction_cancel failed");
 120         }
 121
 122         return false;
 123 }
 124
 125 /*******************************************************************
 126  Fake up a Everyone, default access as a default.
 127  def_access is a GENERIC_XXX access mode.
 128  ********************************************************************/
 129
 130 SEC_DESC *get_share_security_default( TALLOC_CTX *ctx, size_t *psize, uint32 def_access)
 131 {
 132         uint32_t sa;
 133         SEC_ACE ace;
 134         SEC_ACL *psa = NULL;
 135         SEC_DESC *psd = NULL;
 136         uint32 spec_access = def_access;
 137
 138         se_map_generic(&spec_access, &file_generic_mapping);
 139
 140         sa = (def_access | spec_access );
 141         init_sec_ace(&ace, &global_sid_World, SEC_ACE_TYPE_ACCESS_ALLOWED, sa, 0);
 142
 143         if ((psa = make_sec_acl(ctx, NT4_ACL_REVISION, 1, &ace)) != NULL) {
 144                 psd = make_sec_desc(ctx, SECURITY_DESCRIPTOR_REVISION_1,
 145                                     SEC_DESC_SELF_RELATIVE, NULL, NULL, NULL,
 146                                     psa, psize);
 147         }
 148
 149         if (!psd) {
 150                 DEBUG(0,("get_share_security: Failed to make SEC_DESC.\n"));
 151                 return NULL;
 152         }
 153
 154         return psd;
 155 }
 156
 157 /*******************************************************************
 158  Pull a security descriptor from the share tdb.
 159  ********************************************************************/
 160
 161 SEC_DESC *get_share_security( TALLOC_CTX *ctx, const char *servicename,
 162                               size_t *psize)
 163 {
 164         char *key;
 165         SEC_DESC *psd = NULL;
 166         TDB_DATA data;
 167         NTSTATUS status;
 168
 169         if (!share_info_db_init()) {
 170                 return NULL;
 171         }
 172
 173         if (!(key = talloc_asprintf(ctx, "SECDESC/%s", servicename))) {
 174                 DEBUG(0, ("talloc_asprintf failed\n"));
 175                 return NULL;
 176         }
 177
 178         data = dbwrap_fetch_bystring(share_db, talloc_tos(), key);
 179
 180         TALLOC_FREE(key);
 181
 182         if (data.dptr == NULL) {
 183                 return get_share_security_default(ctx, psize,
 184                                                   GENERIC_ALL_ACCESS);
 185         }
 186
 187         status = unmarshall_sec_desc(ctx, data.dptr, data.dsize, &psd);
 188
 189         TALLOC_FREE(data.dptr);
 190
 191         if (!NT_STATUS_IS_OK(status)) {
 192                 DEBUG(0, ("unmarshall_sec_desc failed: %s\n",
 193                           nt_errstr(status)));
 194                 return NULL;
 195         }
 196
 197         if (psd)
 198                 *psize = ndr_size_security_descriptor(psd, 0);
 199
 200         return psd;
 201 }
 202
 203 /*******************************************************************
 204  Store a security descriptor in the share db.
 205  ********************************************************************/
 206
 207 bool set_share_security(const char *share_name, SEC_DESC *psd)
 208 {
 209         TALLOC_CTX *frame;
 210         char *key;
 211         bool ret = False;
 212         TDB_DATA blob;
 213         NTSTATUS status;
 214
 215         if (!share_info_db_init()) {
 216                 return False;
 217         }
 218
 219         frame = talloc_stackframe();
 220
 221         status = marshall_sec_desc(frame, psd, &blob.dptr, &blob.dsize);
 222
 223         if (!NT_STATUS_IS_OK(status)) {
 224                 DEBUG(0, ("marshall_sec_desc failed: %s\n",
 225                           nt_errstr(status)));
 226                 goto out;
 227         }
 228
 229         if (!(key = talloc_asprintf(frame, "SECDESC/%s", share_name))) {
 230                 DEBUG(0, ("talloc_asprintf failed\n"));
 231                 goto out;
 232         }
 233
 234         status = dbwrap_trans_store(share_db, string_term_tdb_data(key), blob,
 235                                     TDB_REPLACE);
 236         if (!NT_STATUS_IS_OK(status)) {
 237                 DEBUG(1, ("set_share_security: Failed to store secdesc for "
 238                           "%s: %s\n", share_name, nt_errstr(status)));
 239                 goto out;
 240         }
 241
 242         DEBUG(5,("set_share_security: stored secdesc for %s\n", share_name ));
 243         ret = True;
 244
 245  out:
 246         TALLOC_FREE(frame);
 247         return ret;
 248 }
 249
 250 /*******************************************************************
 251  Delete a security descriptor.
 252 ********************************************************************/
 253
 254 bool delete_share_security(const char *servicename)
 255 {
 256         TDB_DATA kbuf;
 257         char *key;
 258         NTSTATUS status;
 259
 260         if (!(key = talloc_asprintf(talloc_tos(), "SECDESC/%s",
 261                                     servicename))) {
 262                 return False;
 263         }
 264         kbuf = string_term_tdb_data(key);
 265
 266         status = dbwrap_trans_delete(share_db, kbuf);
 267         if (!NT_STATUS_IS_OK(status)) {
 268                 DEBUG(0, ("delete_share_security: Failed to delete entry for "
 269                           "share %s: %s\n", servicename, nt_errstr(status)));
 270                 return False;
 271         }
 272
 273         return True;
 274 }
 275
 276 /*******************************************************************
 277  Can this user access with share with the required permissions ?
 278 ********************************************************************/
 279
 280 bool share_access_check(const NT_USER_TOKEN *token, const char *sharename,
 281                         uint32 desired_access)
 282 {
 283         uint32 granted;
 284         NTSTATUS status;
 285         SEC_DESC *psd = NULL;
 286         size_t sd_size;
 287
 288         psd = get_share_security(talloc_tos(), sharename, &sd_size);
 289
 290         if (!psd) {
 291                 return True;
 292         }
 293
 294         status = se_access_check(psd, token, desired_access, &granted);
 295
 296         TALLOC_FREE(psd);
 297
 298         return NT_STATUS_IS_OK(status);
 299 }
 300
 301 /***************************************************************************
 302  Parse the contents of an acl string from a usershare file.
 303 ***************************************************************************/
 304
 305 bool parse_usershare_acl(TALLOC_CTX *ctx, const char *acl_str, SEC_DESC **ppsd)
 306 {
 307         size_t s_size = 0;
 308         const char *pacl = acl_str;
 309         int num_aces = 0;
 310         SEC_ACE *ace_list = NULL;
 311         SEC_ACL *psa = NULL;
 312         SEC_DESC *psd = NULL;
 313         size_t sd_size = 0;
 314         int i;
 315
 316         *ppsd = NULL;
 317
 318         /* If the acl string is blank return "Everyone:R" */
 319         if (!*acl_str) {
 320                 SEC_DESC *default_psd = get_share_security_default(ctx, &s_size, GENERIC_READ_ACCESS);
 321                 if (!default_psd) {
 322                         return False;
 323                 }
 324                 *ppsd = default_psd;
 325                 return True;
 326         }
 327
 328         num_aces = 1;
 329
 330         /* Add the number of ',' characters to get the number of aces. */
 331         num_aces += count_chars(pacl,',');
 332
 333         ace_list = TALLOC_ARRAY(ctx, SEC_ACE, num_aces);
 334         if (!ace_list) {
 335                 return False;
 336         }
 337
 338         for (i = 0; i < num_aces; i++) {
 339                 uint32_t sa;
 340                 uint32 g_access;
 341                 uint32 s_access;
 342                 DOM_SID sid;
 343                 char *sidstr;
 344                 enum security_ace_type type = SEC_ACE_TYPE_ACCESS_ALLOWED;
 345
 346                 if (!next_token_talloc(ctx, &pacl, &sidstr, ":")) {
 347                         DEBUG(0,("parse_usershare_acl: malformed usershare acl looking "
 348                                 "for ':' in string '%s'\n", pacl));
 349                         return False;
 350                 }
 351
 352                 if (!string_to_sid(&sid, sidstr)) {
 353                         DEBUG(0,("parse_usershare_acl: failed to convert %s to sid.\n",
 354                                 sidstr ));
 355                         return False;
 356                 }
 357
 358                 switch (*pacl) {
 359                         case 'F': /* Full Control, ie. R+W */
 360                         case 'f': /* Full Control, ie. R+W */
 361                                 s_access = g_access = GENERIC_ALL_ACCESS;
 362                                 break;
 363                         case 'R': /* Read only. */
 364                         case 'r': /* Read only. */
 365                                 s_access = g_access = GENERIC_READ_ACCESS;
 366                                 break;
 367                         case 'D': /* Deny all to this SID. */
 368                         case 'd': /* Deny all to this SID. */
 369                                 type = SEC_ACE_TYPE_ACCESS_DENIED;
 370                                 s_access = g_access = GENERIC_ALL_ACCESS;
 371                                 break;
 372                         default:
 373                                 DEBUG(0,("parse_usershare_acl: unknown acl type at %s.\n",
 374                                         pacl ));
 375                                 return False;
 376                 }
 377
 378                 pacl++;
 379                 if (*pacl && *pacl != ',') {
 380                         DEBUG(0,("parse_usershare_acl: bad acl string at %s.\n",
 381                                 pacl ));
 382                         return False;
 383                 }
 384                 pacl++; /* Go past any ',' */
 385
 386                 se_map_generic(&s_access, &file_generic_mapping);
 387                 sa = (g_access | s_access);
 388                 init_sec_ace(&ace_list[i], &sid, type, sa, 0);
 389         }
 390
 391         if ((psa = make_sec_acl(ctx, NT4_ACL_REVISION, num_aces, ace_list)) != NULL) {
 392                 psd = make_sec_desc(ctx, SECURITY_DESCRIPTOR_REVISION_1,
 393                                     SEC_DESC_SELF_RELATIVE, NULL, NULL, NULL,
 394                                     psa, &sd_size);
 395         }
 396
 397         if (!psd) {
 398                 DEBUG(0,("parse_usershare_acl: Failed to make SEC_DESC.\n"));
 399                 return False;
 400         }
 401
 402         *ppsd = psd;
 403         return True;
 404 }