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 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(lock_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                         lock_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         prs_struct ps;
 114         fstring key;
 115         SEC_DESC *psd = NULL;
 116
 117         if (!share_info_db_init()) {
 118                 return NULL;
 119         }
 120
 121         *psize = 0;
 122
 123         /* Fetch security descriptor from tdb */
 124
 125         slprintf(key, sizeof(key)-1, "SECDESC/%s", servicename);
 126
 127         if (tdb_prs_fetch_bystring(share_tdb, key, &ps, ctx)!=0 ||
 128                 !sec_io_desc("get_share_security", &psd, &ps, 1)) {
 129
 130                 DEBUG(4, ("get_share_security: using default secdesc for %s\n",
 131                           servicename));
 132
 133                 return get_share_security_default(ctx, psize, GENERIC_ALL_ACCESS);
 134         }
 135
 136         if (psd)
 137                 *psize = sec_desc_size(psd);
 138
 139         prs_mem_free(&ps);
 140         return psd;
 141 }
 142
 143 /*******************************************************************
 144  Store a security descriptor in the share db.
 145  ********************************************************************/
 146
 147 BOOL set_share_security(const char *share_name, SEC_DESC *psd)
 148 {
 149         prs_struct ps;
 150         TALLOC_CTX *mem_ctx = NULL;
 151         fstring key;
 152         BOOL ret = False;
 153
 154         if (!share_info_db_init()) {
 155                 return False;
 156         }
 157
 158         mem_ctx = talloc_init("set_share_security");
 159         if (mem_ctx == NULL)
 160                 return False;
 161
 162         prs_init(&ps, (uint32)sec_desc_size(psd), mem_ctx, MARSHALL);
 163
 164         if (!sec_io_desc("share_security", &psd, &ps, 1))
 165                 goto out;
 166
 167         slprintf(key, sizeof(key)-1, "SECDESC/%s", share_name);
 168
 169         if (tdb_prs_store_bystring(share_tdb, key, &ps)==0) {
 170                 ret = True;
 171                 DEBUG(5,("set_share_security: stored secdesc for %s\n", share_name ));
 172         } else {
 173                 DEBUG(1,("set_share_security: Failed to store secdesc for %s\n", share_name ));
 174         }
 175
 176         /* Free malloc'ed memory */
 177
 178 out:
 179
 180         prs_mem_free(&ps);
 181         TALLOC_FREE(mem_ctx);
 182         return ret;
 183 }
 184
 185 /*******************************************************************
 186  Delete a security descriptor.
 187 ********************************************************************/
 188
 189 BOOL delete_share_security(const struct share_params *params)
 190 {
 191         TDB_DATA kbuf;
 192         fstring key;
 193
 194         slprintf(key, sizeof(key)-1, "SECDESC/%s",
 195                  lp_servicename(params->service));
 196         kbuf = string_term_tdb_data(key);
 197
 198         if (tdb_trans_delete(share_tdb, kbuf) != 0) {
 199                 DEBUG(0,("delete_share_security: Failed to delete entry for share %s\n",
 200                          lp_servicename(params->service) ));
 201                 return False;
 202         }
 203
 204         return True;
 205 }
 206
 207 /*******************************************************************
 208  Can this user access with share with the required permissions ?
 209 ********************************************************************/
 210
 211 BOOL share_access_check(const NT_USER_TOKEN *token, const char *sharename,
 212                         uint32 desired_access)
 213 {
 214         uint32 granted;
 215         NTSTATUS status;
 216         TALLOC_CTX *mem_ctx = NULL;
 217         SEC_DESC *psd = NULL;
 218         size_t sd_size;
 219         BOOL ret = True;
 220
 221         if (!(mem_ctx = talloc_init("share_access_check"))) {
 222                 return False;
 223         }
 224
 225         psd = get_share_security(mem_ctx, sharename, &sd_size);
 226
 227         if (!psd) {
 228                 TALLOC_FREE(mem_ctx);
 229                 return True;
 230         }
 231
 232         ret = se_access_check(psd, token, desired_access, &granted, &status);
 233
 234         talloc_destroy(mem_ctx);
 235         return ret;
 236 }
 237
 238 /***************************************************************************
 239  Parse the contents of an acl string from a usershare file.
 240 ***************************************************************************/
 241
 242 BOOL parse_usershare_acl(TALLOC_CTX *ctx, const char *acl_str, SEC_DESC **ppsd)
 243 {
 244         size_t s_size = 0;
 245         const char *pacl = acl_str;
 246         int num_aces = 0;
 247         SEC_ACE *ace_list = NULL;
 248         SEC_ACL *psa = NULL;
 249         SEC_DESC *psd = NULL;
 250         size_t sd_size = 0;
 251         int i;
 252
 253         *ppsd = NULL;
 254
 255         /* If the acl string is blank return "Everyone:R" */
 256         if (!*acl_str) {
 257                 SEC_DESC *default_psd = get_share_security_default(ctx, &s_size, GENERIC_READ_ACCESS);
 258                 if (!default_psd) {
 259                         return False;
 260                 }
 261                 *ppsd = default_psd;
 262                 return True;
 263         }
 264
 265         num_aces = 1;
 266
 267         /* Add the number of ',' characters to get the number of aces. */
 268         num_aces += count_chars(pacl,',');
 269
 270         ace_list = TALLOC_ARRAY(ctx, SEC_ACE, num_aces);
 271         if (!ace_list) {
 272                 return False;
 273         }
 274
 275         for (i = 0; i < num_aces; i++) {
 276                 SEC_ACCESS sa;
 277                 uint32 g_access;
 278                 uint32 s_access;
 279                 DOM_SID sid;
 280                 fstring sidstr;
 281                 uint8 type = SEC_ACE_TYPE_ACCESS_ALLOWED;
 282
 283                 if (!next_token(&pacl, sidstr, ":", sizeof(sidstr))) {
 284                         DEBUG(0,("parse_usershare_acl: malformed usershare acl looking "
 285                                 "for ':' in string '%s'\n", pacl));
 286                         return False;
 287                 }
 288
 289                 if (!string_to_sid(&sid, sidstr)) {
 290                         DEBUG(0,("parse_usershare_acl: failed to convert %s to sid.\n",
 291                                 sidstr ));
 292                         return False;
 293                 }
 294
 295                 switch (*pacl) {
 296                         case 'F': /* Full Control, ie. R+W */
 297                         case 'f': /* Full Control, ie. R+W */
 298                                 s_access = g_access = GENERIC_ALL_ACCESS;
 299                                 break;
 300                         case 'R': /* Read only. */
 301                         case 'r': /* Read only. */
 302                                 s_access = g_access = GENERIC_READ_ACCESS;
 303                                 break;
 304                         case 'D': /* Deny all to this SID. */
 305                         case 'd': /* Deny all to this SID. */
 306                                 type = SEC_ACE_TYPE_ACCESS_DENIED;
 307                                 s_access = g_access = GENERIC_ALL_ACCESS;
 308                                 break;
 309                         default:
 310                                 DEBUG(0,("parse_usershare_acl: unknown acl type at %s.\n",
 311                                         pacl ));
 312                                 return False;
 313                 }
 314
 315                 pacl++;
 316                 if (*pacl && *pacl != ',') {
 317                         DEBUG(0,("parse_usershare_acl: bad acl string at %s.\n",
 318                                 pacl ));
 319                         return False;
 320                 }
 321                 pacl++; /* Go past any ',' */
 322
 323                 se_map_generic(&s_access, &file_generic_mapping);
 324                 init_sec_access(&sa, g_access | s_access );
 325                 init_sec_ace(&ace_list[i], &sid, type, sa, 0);
 326         }
 327
 328         if ((psa = make_sec_acl(ctx, NT4_ACL_REVISION, num_aces, ace_list)) != NULL) {
 329                 psd = make_sec_desc(ctx, SEC_DESC_REVISION, SEC_DESC_SELF_RELATIVE, NULL, NULL, NULL, psa, &sd_size);
 330         }
 331
 332         if (!psd) {
 333                 DEBUG(0,("parse_usershare_acl: Failed to make SEC_DESC.\n"));
 334                 return False;
 335         }
 336
 337         *ppsd = psd;
 338         return True;
 339 }