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 2 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, write to the Free Software
  18  *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  19  */
  20
  21 #include "includes.h"
  22
  23 /*******************************************************************
  24  Create the share security tdb.
  25  ********************************************************************/
  26
  27 static TDB_CONTEXT *share_tdb; /* used for share security descriptors */
  28 #define SHARE_DATABASE_VERSION_V1 1
  29 #define SHARE_DATABASE_VERSION_V2 2 /* version id in little endian. */
  30
  31 /* Map generic permissions to file object specific permissions */
  32
  33 static struct generic_mapping file_generic_mapping = {
  34         FILE_GENERIC_READ,
  35         FILE_GENERIC_WRITE,
  36         FILE_GENERIC_EXECUTE,
  37         FILE_GENERIC_ALL
  38 };
  39
  40
  41 BOOL share_info_db_init(void)
  42 {
  43         const char *vstring = "INFO/version";
  44         int32 vers_id;
  45
  46         if (share_tdb) {
  47                 return True;
  48         }
  49
  50         share_tdb = tdb_open_log(lock_path("share_info.tdb"), 0, TDB_DEFAULT, O_RDWR|O_CREAT, 0600);
  51         if (!share_tdb) {
  52                 DEBUG(0,("Failed to open share info database %s (%s)\n",
  53                         lock_path("share_info.tdb"), strerror(errno) ));
  54                 return False;
  55         }
  56
  57         /* handle a Samba upgrade */
  58         tdb_lock_bystring(share_tdb, vstring);
  59
  60         /* Cope with byte-reversed older versions of the db. */
  61         vers_id = tdb_fetch_int32(share_tdb, vstring);
  62         if ((vers_id == SHARE_DATABASE_VERSION_V1) || (IREV(vers_id) == SHARE_DATABASE_VERSION_V1)) {
  63                 /* Written on a bigendian machine with old fetch_int code. Save as le. */
  64                 tdb_store_int32(share_tdb, vstring, SHARE_DATABASE_VERSION_V2);
  65                 vers_id = SHARE_DATABASE_VERSION_V2;
  66         }
  67
  68         if (vers_id != SHARE_DATABASE_VERSION_V2) {
  69                 tdb_traverse(share_tdb, tdb_traverse_delete_fn, NULL);
  70                 tdb_store_int32(share_tdb, vstring, SHARE_DATABASE_VERSION_V2);
  71         }
  72         tdb_unlock_bystring(share_tdb, vstring);
  73
  74         return True;
  75 }
  76
  77 /*******************************************************************
  78  Fake up a Everyone, default access as a default.
  79  def_access is a GENERIC_XXX access mode.
  80  ********************************************************************/
  81
  82 SEC_DESC *get_share_security_default( TALLOC_CTX *ctx, size_t *psize, uint32 def_access)
  83 {
  84         SEC_ACCESS sa;
  85         SEC_ACE ace;
  86         SEC_ACL *psa = NULL;
  87         SEC_DESC *psd = NULL;
  88         uint32 spec_access = def_access;
  89
  90         se_map_generic(&spec_access, &file_generic_mapping);
  91
  92         init_sec_access(&sa, def_access | spec_access );
  93         init_sec_ace(&ace, &global_sid_World, SEC_ACE_TYPE_ACCESS_ALLOWED, sa, 0);
  94
  95         if ((psa = make_sec_acl(ctx, NT4_ACL_REVISION, 1, &ace)) != NULL) {
  96                 psd = make_sec_desc(ctx, SEC_DESC_REVISION, SEC_DESC_SELF_RELATIVE, NULL, NULL, NULL, psa, psize);
  97         }
  98
  99         if (!psd) {
 100                 DEBUG(0,("get_share_security: Failed to make SEC_DESC.\n"));
 101                 return NULL;
 102         }
 103
 104         return psd;
 105 }
 106
 107 /*******************************************************************
 108  Pull a security descriptor from the share tdb.
 109  ********************************************************************/
 110
 111 SEC_DESC *get_share_security( TALLOC_CTX *ctx, const char *servicename,
 112                               size_t *psize)
 113 {
 114         prs_struct ps;
 115         fstring key;
 116         SEC_DESC *psd = NULL;
 117
 118         if (!share_info_db_init()) {
 119                 return NULL;
 120         }
 121
 122         *psize = 0;
 123
 124         /* Fetch security descriptor from tdb */
 125
 126         slprintf(key, sizeof(key)-1, "SECDESC/%s", servicename);
 127
 128         if (tdb_prs_fetch(share_tdb, key, &ps, ctx)!=0 ||
 129                 !sec_io_desc("get_share_security", &psd, &ps, 1)) {
 130
 131                 DEBUG(4, ("get_share_security: using default secdesc for %s\n",
 132                           servicename));
 133
 134                 return get_share_security_default(ctx, psize, GENERIC_ALL_ACCESS);
 135         }
 136
 137         if (psd)
 138                 *psize = sec_desc_size(psd);
 139
 140         prs_mem_free(&ps);
 141         return psd;
 142 }
 143
 144 /*******************************************************************
 145  Store a security descriptor in the share db.
 146  ********************************************************************/
 147
 148 BOOL set_share_security(const char *share_name, SEC_DESC *psd)
 149 {
 150         prs_struct ps;
 151         TALLOC_CTX *mem_ctx = NULL;
 152         fstring key;
 153         BOOL ret = False;
 154
 155         if (!share_info_db_init()) {
 156                 return False;
 157         }
 158
 159         mem_ctx = talloc_init("set_share_security");
 160         if (mem_ctx == NULL)
 161                 return False;
 162
 163         prs_init(&ps, (uint32)sec_desc_size(psd), mem_ctx, MARSHALL);
 164
 165         if (!sec_io_desc("share_security", &psd, &ps, 1))
 166                 goto out;
 167
 168         slprintf(key, sizeof(key)-1, "SECDESC/%s", share_name);
 169
 170         if (tdb_prs_store(share_tdb, key, &ps)==0) {
 171                 ret = True;
 172                 DEBUG(5,("set_share_security: stored secdesc for %s\n", share_name ));
 173         } else {
 174                 DEBUG(1,("set_share_security: Failed to store secdesc for %s\n", share_name ));
 175         }
 176
 177         /* Free malloc'ed memory */
 178
 179 out:
 180
 181         prs_mem_free(&ps);
 182         if (mem_ctx)
 183                 talloc_destroy(mem_ctx);
 184         return ret;
 185 }
 186
 187 /*******************************************************************
 188  Delete a security descriptor.
 189 ********************************************************************/
 190
 191 BOOL delete_share_security(const struct share_params *params)
 192 {
 193         TDB_DATA kbuf;
 194         fstring key;
 195
 196         slprintf(key, sizeof(key)-1, "SECDESC/%s",
 197                  lp_servicename(params->service));
 198         kbuf.dptr = key;
 199         kbuf.dsize = strlen(key)+1;
 200
 201         if (tdb_trans_delete(share_tdb, kbuf) != 0) {
 202                 DEBUG(0,("delete_share_security: Failed to delete entry for share %s\n",
 203                          lp_servicename(params->service) ));
 204                 return False;
 205         }
 206
 207         return True;
 208 }
 209
 210 /*******************************************************************
 211  Can this user access with share with the required permissions ?
 212 ********************************************************************/
 213
 214 BOOL share_access_check(const NT_USER_TOKEN *token, const char *sharename,
 215                         uint32 desired_access)
 216 {
 217         uint32 granted;
 218         NTSTATUS status;
 219         TALLOC_CTX *mem_ctx = NULL;
 220         SEC_DESC *psd = NULL;
 221         size_t sd_size;
 222         BOOL ret = True;
 223
 224         if (!(mem_ctx = talloc_init("share_access_check"))) {
 225                 return False;
 226         }
 227
 228         psd = get_share_security(mem_ctx, sharename, &sd_size);
 229
 230         if (!psd) {
 231                 TALLOC_FREE(mem_ctx);
 232                 return True;
 233         }
 234
 235         ret = se_access_check(psd, token, desired_access, &granted, &status);
 236
 237         talloc_destroy(mem_ctx);
 238         return ret;
 239 }
 240
 241 /***************************************************************************
 242  Parse the contents of an acl string from a usershare file.
 243 ***************************************************************************/
 244
 245 BOOL parse_usershare_acl(TALLOC_CTX *ctx, const char *acl_str, SEC_DESC **ppsd)
 246 {
 247         size_t s_size = 0;
 248         const char *pacl = acl_str;
 249         int num_aces = 0;
 250         SEC_ACE *ace_list = NULL;
 251         SEC_ACL *psa = NULL;
 252         SEC_DESC *psd = NULL;
 253         size_t sd_size = 0;
 254         int i;
 255
 256         *ppsd = NULL;
 257
 258         /* If the acl string is blank return "Everyone:R" */
 259         if (!*acl_str) {
 260                 SEC_DESC *default_psd = get_share_security_default(ctx, &s_size, GENERIC_READ_ACCESS);
 261                 if (!default_psd) {
 262                         return False;
 263                 }
 264                 *ppsd = default_psd;
 265                 return True;
 266         }
 267
 268         num_aces = 1;
 269
 270         /* Add the number of ',' characters to get the number of aces. */
 271         num_aces += count_chars(pacl,',');
 272
 273         ace_list = TALLOC_ARRAY(ctx, SEC_ACE, num_aces);
 274         if (!ace_list) {
 275                 return False;
 276         }
 277
 278         for (i = 0; i < num_aces; i++) {
 279                 SEC_ACCESS sa;
 280                 uint32 g_access;
 281                 uint32 s_access;
 282                 DOM_SID sid;
 283                 fstring sidstr;
 284                 uint8 type = SEC_ACE_TYPE_ACCESS_ALLOWED;
 285
 286                 if (!next_token(&pacl, sidstr, ":", sizeof(sidstr))) {
 287                         DEBUG(0,("parse_usershare_acl: malformed usershare acl looking "
 288                                 "for ':' in string '%s'\n", pacl));
 289                         return False;
 290                 }
 291
 292                 if (!string_to_sid(&sid, sidstr)) {
 293                         DEBUG(0,("parse_usershare_acl: failed to convert %s to sid.\n",
 294                                 sidstr ));
 295                         return False;
 296                 }
 297
 298                 switch (*pacl) {
 299                         case 'F': /* Full Control, ie. R+W */
 300                         case 'f': /* Full Control, ie. R+W */
 301                                 s_access = g_access = GENERIC_ALL_ACCESS;
 302                                 break;
 303                         case 'R': /* Read only. */
 304                         case 'r': /* Read only. */
 305                                 s_access = g_access = GENERIC_READ_ACCESS;
 306                                 break;
 307                         case 'D': /* Deny all to this SID. */
 308                         case 'd': /* Deny all to this SID. */
 309                                 type = SEC_ACE_TYPE_ACCESS_DENIED;
 310                                 s_access = g_access = GENERIC_ALL_ACCESS;
 311                                 break;
 312                         default:
 313                                 DEBUG(0,("parse_usershare_acl: unknown acl type at %s.\n",
 314                                         pacl ));
 315                                 return False;
 316                 }
 317
 318                 pacl++;
 319                 if (*pacl && *pacl != ',') {
 320                         DEBUG(0,("parse_usershare_acl: bad acl string at %s.\n",
 321                                 pacl ));
 322                         return False;
 323                 }
 324                 pacl++; /* Go past any ',' */
 325
 326                 se_map_generic(&s_access, &file_generic_mapping);
 327                 init_sec_access(&sa, g_access | s_access );
 328                 init_sec_ace(&ace_list[i], &sid, type, sa, 0);
 329         }
 330
 331         if ((psa = make_sec_acl(ctx, NT4_ACL_REVISION, num_aces, ace_list)) != NULL) {
 332                 psd = make_sec_desc(ctx, SEC_DESC_REVISION, SEC_DESC_SELF_RELATIVE, NULL, NULL, NULL, psa, &sd_size);
 333         }
 334
 335         if (!psd) {
 336                 DEBUG(0,("parse_usershare_acl: Failed to make SEC_DESC.\n"));
 337                 return False;
 338         }
 339
 340         *ppsd = psd;
 341         return True;
 342 }