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
  22 /*******************************************************************
  23  Create the share security tdb.
  24  ********************************************************************/
  25
  26 static TDB_CONTEXT *share_tdb; /* 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
  40 bool share_info_db_init(void)
  41 {
  42         const char *vstring = "INFO/version";
  43         int32 vers_id;
  44
  45         if (share_tdb) {
  46                 return True;
  47         }
  48
  49         share_tdb = tdb_open_log(state_path("share_info.tdb"), 0, TDB_DEFAULT, O_RDWR|O_CREAT, 0600);
  50         if (!share_tdb) {
  51                 DEBUG(0,("Failed to open share info database %s (%s)\n",
  52                         state_path("share_info.tdb"), strerror(errno) ));
  53                 return False;
  54         }
  55
  56         /* handle a Samba upgrade */
  57         tdb_lock_bystring(share_tdb, vstring);
  58
  59         /* Cope with byte-reversed older versions of the db. */
  60         vers_id = tdb_fetch_int32(share_tdb, vstring);
  61         if ((vers_id == SHARE_DATABASE_VERSION_V1) || (IREV(vers_id) == SHARE_DATABASE_VERSION_V1)) {
  62                 /* Written on a bigendian machine with old fetch_int code. Save as le. */
  63                 tdb_store_int32(share_tdb, vstring, SHARE_DATABASE_VERSION_V2);
  64                 vers_id = SHARE_DATABASE_VERSION_V2;
  65         }
  66
  67         if (vers_id != SHARE_DATABASE_VERSION_V2) {
  68                 tdb_traverse(share_tdb, tdb_traverse_delete_fn, NULL);
  69                 tdb_store_int32(share_tdb, vstring, SHARE_DATABASE_VERSION_V2);
  70         }
  71         tdb_unlock_bystring(share_tdb, vstring);
  72
  73         return True;
  74 }
  75
  76 /*******************************************************************
  77  Fake up a Everyone, default access as a default.
  78  def_access is a GENERIC_XXX access mode.
  79  ********************************************************************/
  80
  81 SEC_DESC *get_share_security_default( TALLOC_CTX *ctx, size_t *psize, uint32 def_access)
  82 {
  83         SEC_ACCESS sa;
  84         SEC_ACE ace;
  85         SEC_ACL *psa = NULL;
  86         SEC_DESC *psd = NULL;
  87         uint32 spec_access = def_access;
  88
  89         se_map_generic(&spec_access, &file_generic_mapping);
  90
  91         init_sec_access(&sa, def_access | spec_access );
  92         init_sec_ace(&ace, &global_sid_World, SEC_ACE_TYPE_ACCESS_ALLOWED, sa, 0);
  93
  94         if ((psa = make_sec_acl(ctx, NT4_ACL_REVISION, 1, &ace)) != NULL) {
  95                 psd = make_sec_desc(ctx, SEC_DESC_REVISION, SEC_DESC_SELF_RELATIVE, NULL, NULL, NULL, psa, psize);
  96         }
  97
  98         if (!psd) {
  99                 DEBUG(0,("get_share_security: Failed to make SEC_DESC.\n"));
 100                 return NULL;
 101         }
 102
 103         return psd;
 104 }
 105
 106 /*******************************************************************
 107  Pull a security descriptor from the share tdb.
 108  ********************************************************************/
 109
 110 SEC_DESC *get_share_security( TALLOC_CTX *ctx, const char *servicename,
 111                               size_t *psize)
 112 {
 113         char *key;
 114         SEC_DESC *psd = NULL;
 115         TDB_DATA data;
 116         NTSTATUS status;
 117
 118         if (!share_info_db_init()) {
 119                 return NULL;
 120         }
 121
 122         if (!(key = talloc_asprintf(ctx, "SECDESC/%s", servicename))) {
 123                 DEBUG(0, ("talloc_asprintf failed\n"));
 124                 return NULL;
 125         }
 126
 127         data = tdb_fetch_bystring(share_tdb, key);
 128
 129         TALLOC_FREE(key);
 130
 131         if (data.dptr == NULL) {
 132                 return get_share_security_default(ctx, psize,
 133                                                   GENERIC_ALL_ACCESS);
 134         }
 135
 136         status = unmarshall_sec_desc(ctx, data.dptr, data.dsize, &psd);
 137
 138         if (!NT_STATUS_IS_OK(status)) {
 139                 DEBUG(0, ("unmarshall_sec_desc failed: %s\n",
 140                           nt_errstr(status)));
 141                 return NULL;
 142         }
 143
 144         if (psd)
 145                 *psize = sec_desc_size(psd);
 146
 147         return psd;
 148 }
 149
 150 /*******************************************************************
 151  Store a security descriptor in the share db.
 152  ********************************************************************/
 153
 154 bool set_share_security(const char *share_name, SEC_DESC *psd)
 155 {
 156         TALLOC_CTX *frame;
 157         char *key;
 158         bool ret = False;
 159         TDB_DATA blob;
 160         NTSTATUS status;
 161
 162         if (!share_info_db_init()) {
 163                 return False;
 164         }
 165
 166         frame = talloc_stackframe();
 167
 168         status = marshall_sec_desc(frame, psd, &blob.dptr, &blob.dsize);
 169
 170         if (!NT_STATUS_IS_OK(status)) {
 171                 DEBUG(0, ("marshall_sec_desc failed: %s\n",
 172                           nt_errstr(status)));
 173                 goto out;
 174         }
 175
 176         if (!(key = talloc_asprintf(frame, "SECDESC/%s", share_name))) {
 177                 DEBUG(0, ("talloc_asprintf failed\n"));
 178                 goto out;
 179         }
 180
 181         if (tdb_trans_store_bystring(share_tdb, key, blob,
 182                                      TDB_REPLACE) == -1) {
 183                 DEBUG(1,("set_share_security: Failed to store secdesc for "
 184                          "%s\n", share_name ));
 185                 goto out;
 186         }
 187
 188         DEBUG(5,("set_share_security: stored secdesc for %s\n", share_name ));
 189         ret = True;
 190
 191  out:
 192         TALLOC_FREE(frame);
 193         return ret;
 194 }
 195
 196 /*******************************************************************
 197  Delete a security descriptor.
 198 ********************************************************************/
 199
 200 bool delete_share_security(const char *servicename)
 201 {
 202         TDB_DATA kbuf;
 203         char *key;
 204
 205         if (!(key = talloc_asprintf(talloc_tos(), "SECDESC/%s",
 206                                     servicename))) {
 207                 return False;
 208         }
 209         kbuf = string_term_tdb_data(key);
 210
 211         if (tdb_trans_delete(share_tdb, kbuf) != 0) {
 212                 DEBUG(0, ("delete_share_security: Failed to delete entry for "
 213                           "share %s\n", servicename));
 214                 return False;
 215         }
 216
 217         return True;
 218 }
 219
 220 /*******************************************************************
 221  Can this user access with share with the required permissions ?
 222 ********************************************************************/
 223
 224 bool share_access_check(const NT_USER_TOKEN *token, const char *sharename,
 225                         uint32 desired_access)
 226 {
 227         uint32 granted;
 228         NTSTATUS status;
 229         TALLOC_CTX *mem_ctx = NULL;
 230         SEC_DESC *psd = NULL;
 231         size_t sd_size;
 232         bool ret = True;
 233
 234         if (!(mem_ctx = talloc_init("share_access_check"))) {
 235                 return False;
 236         }
 237
 238         psd = get_share_security(mem_ctx, sharename, &sd_size);
 239
 240         if (!psd) {
 241                 TALLOC_FREE(mem_ctx);
 242                 return True;
 243         }
 244
 245         ret = se_access_check(psd, token, desired_access, &granted, &status);
 246
 247         talloc_destroy(mem_ctx);
 248         return ret;
 249 }
 250
 251 /***************************************************************************
 252  Parse the contents of an acl string from a usershare file.
 253 ***************************************************************************/
 254
 255 bool parse_usershare_acl(TALLOC_CTX *ctx, const char *acl_str, SEC_DESC **ppsd)
 256 {
 257         size_t s_size = 0;
 258         const char *pacl = acl_str;
 259         int num_aces = 0;
 260         SEC_ACE *ace_list = NULL;
 261         SEC_ACL *psa = NULL;
 262         SEC_DESC *psd = NULL;
 263         size_t sd_size = 0;
 264         int i;
 265
 266         *ppsd = NULL;
 267
 268         /* If the acl string is blank return "Everyone:R" */
 269         if (!*acl_str) {
 270                 SEC_DESC *default_psd = get_share_security_default(ctx, &s_size, GENERIC_READ_ACCESS);
 271                 if (!default_psd) {
 272                         return False;
 273                 }
 274                 *ppsd = default_psd;
 275                 return True;
 276         }
 277
 278         num_aces = 1;
 279
 280         /* Add the number of ',' characters to get the number of aces. */
 281         num_aces += count_chars(pacl,',');
 282
 283         ace_list = TALLOC_ARRAY(ctx, SEC_ACE, num_aces);
 284         if (!ace_list) {
 285                 return False;
 286         }
 287
 288         for (i = 0; i < num_aces; i++) {
 289                 SEC_ACCESS sa;
 290                 uint32 g_access;
 291                 uint32 s_access;
 292                 DOM_SID sid;
 293                 fstring sidstr;
 294                 uint8 type = SEC_ACE_TYPE_ACCESS_ALLOWED;
 295
 296                 if (!next_token(&pacl, sidstr, ":", sizeof(sidstr))) {
 297                         DEBUG(0,("parse_usershare_acl: malformed usershare acl looking "
 298                                 "for ':' in string '%s'\n", pacl));
 299                         return False;
 300                 }
 301
 302                 if (!string_to_sid(&sid, sidstr)) {
 303                         DEBUG(0,("parse_usershare_acl: failed to convert %s to sid.\n",
 304                                 sidstr ));
 305                         return False;
 306                 }
 307
 308                 switch (*pacl) {
 309                         case 'F': /* Full Control, ie. R+W */
 310                         case 'f': /* Full Control, ie. R+W */
 311                                 s_access = g_access = GENERIC_ALL_ACCESS;
 312                                 break;
 313                         case 'R': /* Read only. */
 314                         case 'r': /* Read only. */
 315                                 s_access = g_access = GENERIC_READ_ACCESS;
 316                                 break;
 317                         case 'D': /* Deny all to this SID. */
 318                         case 'd': /* Deny all to this SID. */
 319                                 type = SEC_ACE_TYPE_ACCESS_DENIED;
 320                                 s_access = g_access = GENERIC_ALL_ACCESS;
 321                                 break;
 322                         default:
 323                                 DEBUG(0,("parse_usershare_acl: unknown acl type at %s.\n",
 324                                         pacl ));
 325                                 return False;
 326                 }
 327
 328                 pacl++;
 329                 if (*pacl && *pacl != ',') {
 330                         DEBUG(0,("parse_usershare_acl: bad acl string at %s.\n",
 331                                 pacl ));
 332                         return False;
 333                 }
 334                 pacl++; /* Go past any ',' */
 335
 336                 se_map_generic(&s_access, &file_generic_mapping);
 337                 init_sec_access(&sa, g_access | s_access );
 338                 init_sec_ace(&ace_list[i], &sid, type, sa, 0);
 339         }
 340
 341         if ((psa = make_sec_acl(ctx, NT4_ACL_REVISION, num_aces, ace_list)) != NULL) {
 342                 psd = make_sec_desc(ctx, SEC_DESC_REVISION, SEC_DESC_SELF_RELATIVE, NULL, NULL, NULL, psa, &sd_size);
 343         }
 344
 345         if (!psd) {
 346                 DEBUG(0,("parse_usershare_acl: Failed to make SEC_DESC.\n"));
 347                 return False;
 348         }
 349
 350         *ppsd = psd;
 351         return True;
 352 }