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 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 static 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_wipe_all(share_tdb);
  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, SECURITY_DESCRIPTOR_REVISION_1,
  96                                     SEC_DESC_SELF_RELATIVE, NULL, NULL, NULL,
  97                                     psa, psize);
  98         }
  99
 100         if (!psd) {
 101                 DEBUG(0,("get_share_security: Failed to make SEC_DESC.\n"));
 102                 return NULL;
 103         }
 104
 105         return psd;
 106 }
 107
 108 /*******************************************************************
 109  Pull a security descriptor from the share tdb.
 110  ********************************************************************/
 111
 112 SEC_DESC *get_share_security( TALLOC_CTX *ctx, const char *servicename,
 113                               size_t *psize)
 114 {
 115         char *key;
 116         SEC_DESC *psd = NULL;
 117         TDB_DATA data;
 118         NTSTATUS status;
 119
 120         if (!share_info_db_init()) {
 121                 return NULL;
 122         }
 123
 124         if (!(key = talloc_asprintf(ctx, "SECDESC/%s", servicename))) {
 125                 DEBUG(0, ("talloc_asprintf failed\n"));
 126                 return NULL;
 127         }
 128
 129         data = tdb_fetch_bystring(share_tdb, key);
 130
 131         TALLOC_FREE(key);
 132
 133         if (data.dptr == NULL) {
 134                 return get_share_security_default(ctx, psize,
 135                                                   GENERIC_ALL_ACCESS);
 136         }
 137
 138         status = unmarshall_sec_desc(ctx, data.dptr, data.dsize, &psd);
 139
 140         SAFE_FREE(data.dptr);
 141
 142         if (!NT_STATUS_IS_OK(status)) {
 143                 DEBUG(0, ("unmarshall_sec_desc failed: %s\n",
 144                           nt_errstr(status)));
 145                 return NULL;
 146         }
 147
 148         if (psd)
 149                 *psize = ndr_size_security_descriptor(psd, 0);
 150
 151         return psd;
 152 }
 153
 154 /*******************************************************************
 155  Store a security descriptor in the share db.
 156  ********************************************************************/
 157
 158 bool set_share_security(const char *share_name, SEC_DESC *psd)
 159 {
 160         TALLOC_CTX *frame;
 161         char *key;
 162         bool ret = False;
 163         TDB_DATA blob;
 164         NTSTATUS status;
 165
 166         if (!share_info_db_init()) {
 167                 return False;
 168         }
 169
 170         frame = talloc_stackframe();
 171
 172         status = marshall_sec_desc(frame, psd, &blob.dptr, &blob.dsize);
 173
 174         if (!NT_STATUS_IS_OK(status)) {
 175                 DEBUG(0, ("marshall_sec_desc failed: %s\n",
 176                           nt_errstr(status)));
 177                 goto out;
 178         }
 179
 180         if (!(key = talloc_asprintf(frame, "SECDESC/%s", share_name))) {
 181                 DEBUG(0, ("talloc_asprintf failed\n"));
 182                 goto out;
 183         }
 184
 185         if (tdb_trans_store_bystring(share_tdb, key, blob,
 186                                      TDB_REPLACE) == -1) {
 187                 DEBUG(1,("set_share_security: Failed to store secdesc for "
 188                          "%s\n", share_name ));
 189                 goto out;
 190         }
 191
 192         DEBUG(5,("set_share_security: stored secdesc for %s\n", share_name ));
 193         ret = True;
 194
 195  out:
 196         TALLOC_FREE(frame);
 197         return ret;
 198 }
 199
 200 /*******************************************************************
 201  Delete a security descriptor.
 202 ********************************************************************/
 203
 204 bool delete_share_security(const char *servicename)
 205 {
 206         TDB_DATA kbuf;
 207         char *key;
 208
 209         if (!(key = talloc_asprintf(talloc_tos(), "SECDESC/%s",
 210                                     servicename))) {
 211                 return False;
 212         }
 213         kbuf = string_term_tdb_data(key);
 214
 215         if (tdb_trans_delete(share_tdb, kbuf) != 0) {
 216                 DEBUG(0, ("delete_share_security: Failed to delete entry for "
 217                           "share %s\n", servicename));
 218                 return False;
 219         }
 220
 221         return True;
 222 }
 223
 224 /*******************************************************************
 225  Can this user access with share with the required permissions ?
 226 ********************************************************************/
 227
 228 bool share_access_check(const NT_USER_TOKEN *token, const char *sharename,
 229                         uint32 desired_access)
 230 {
 231         uint32 granted;
 232         NTSTATUS status;
 233         SEC_DESC *psd = NULL;
 234         size_t sd_size;
 235         bool ret = True;
 236
 237         psd = get_share_security(talloc_tos(), sharename, &sd_size);
 238
 239         if (!psd) {
 240                 return True;
 241         }
 242
 243         ret = se_access_check(psd, token, desired_access, &granted, &status);
 244
 245         TALLOC_FREE(psd);
 246
 247         return ret;
 248 }
 249
 250 /***************************************************************************
 251  Parse the contents of an acl string from a usershare file.
 252 ***************************************************************************/
 253
 254 bool parse_usershare_acl(TALLOC_CTX *ctx, const char *acl_str, SEC_DESC **ppsd)
 255 {
 256         size_t s_size = 0;
 257         const char *pacl = acl_str;
 258         int num_aces = 0;
 259         SEC_ACE *ace_list = NULL;
 260         SEC_ACL *psa = NULL;
 261         SEC_DESC *psd = NULL;
 262         size_t sd_size = 0;
 263         int i;
 264
 265         *ppsd = NULL;
 266
 267         /* If the acl string is blank return "Everyone:R" */
 268         if (!*acl_str) {
 269                 SEC_DESC *default_psd = get_share_security_default(ctx, &s_size, GENERIC_READ_ACCESS);
 270                 if (!default_psd) {
 271                         return False;
 272                 }
 273                 *ppsd = default_psd;
 274                 return True;
 275         }
 276
 277         num_aces = 1;
 278
 279         /* Add the number of ',' characters to get the number of aces. */
 280         num_aces += count_chars(pacl,',');
 281
 282         ace_list = TALLOC_ARRAY(ctx, SEC_ACE, num_aces);
 283         if (!ace_list) {
 284                 return False;
 285         }
 286
 287         for (i = 0; i < num_aces; i++) {
 288                 SEC_ACCESS sa;
 289                 uint32 g_access;
 290                 uint32 s_access;
 291                 DOM_SID sid;
 292                 char *sidstr;
 293                 enum security_ace_type type = SEC_ACE_TYPE_ACCESS_ALLOWED;
 294
 295                 if (!next_token_talloc(ctx, &pacl, &sidstr, ":")) {
 296                         DEBUG(0,("parse_usershare_acl: malformed usershare acl looking "
 297                                 "for ':' in string '%s'\n", pacl));
 298                         return False;
 299                 }
 300
 301                 if (!string_to_sid(&sid, sidstr)) {
 302                         DEBUG(0,("parse_usershare_acl: failed to convert %s to sid.\n",
 303                                 sidstr ));
 304                         return False;
 305                 }
 306
 307                 switch (*pacl) {
 308                         case 'F': /* Full Control, ie. R+W */
 309                         case 'f': /* Full Control, ie. R+W */
 310                                 s_access = g_access = GENERIC_ALL_ACCESS;
 311                                 break;
 312                         case 'R': /* Read only. */
 313                         case 'r': /* Read only. */
 314                                 s_access = g_access = GENERIC_READ_ACCESS;
 315                                 break;
 316                         case 'D': /* Deny all to this SID. */
 317                         case 'd': /* Deny all to this SID. */
 318                                 type = SEC_ACE_TYPE_ACCESS_DENIED;
 319                                 s_access = g_access = GENERIC_ALL_ACCESS;
 320                                 break;
 321                         default:
 322                                 DEBUG(0,("parse_usershare_acl: unknown acl type at %s.\n",
 323                                         pacl ));
 324                                 return False;
 325                 }
 326
 327                 pacl++;
 328                 if (*pacl && *pacl != ',') {
 329                         DEBUG(0,("parse_usershare_acl: bad acl string at %s.\n",
 330                                 pacl ));
 331                         return False;
 332                 }
 333                 pacl++; /* Go past any ',' */
 334
 335                 se_map_generic(&s_access, &file_generic_mapping);
 336                 init_sec_access(&sa, g_access | s_access );
 337                 init_sec_ace(&ace_list[i], &sid, type, sa, 0);
 338         }
 339
 340         if ((psa = make_sec_acl(ctx, NT4_ACL_REVISION, num_aces, ace_list)) != NULL) {
 341                 psd = make_sec_desc(ctx, SECURITY_DESCRIPTOR_REVISION_1,
 342                                     SEC_DESC_SELF_RELATIVE, NULL, NULL, NULL,
 343                                     psa, &sd_size);
 344         }
 345
 346         if (!psd) {
 347                 DEBUG(0,("parse_usershare_acl: Failed to make SEC_DESC.\n"));
 348                 return False;
 349         }
 350
 351         *ppsd = psd;
 352         return True;
 353 }