source/lib/util_seaccess.c

   1 /*
   2    Unix SMB/CIFS implementation.
   3    Copyright (C) Luke Kenneth Casson Leighton 1996-2000.
   4    Copyright (C) Tim Potter 2000.
   5    Copyright (C) Re-written by Jeremy Allison 2000.
   6
   7    This program is free software; you can redistribute it and/or modify
   8    it under the terms of the GNU General Public License as published by
   9    the Free Software Foundation; either version 3 of the License, or
  10    (at your option) any later version.
  11
  12    This program is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15    GNU General Public License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with this program.  If not, see <http://www.gnu.org/licenses/>.
  19 */
  20
  21 #include "includes.h"
  22
  23 extern NT_USER_TOKEN anonymous_token;
  24
  25 /*********************************************************************************
  26  Check an ACE against a SID.  We return the remaining needed permission
  27  bits not yet granted. Zero means permission allowed (no more needed bits).
  28 **********************************************************************************/
  29
  30 static uint32 check_ace(SEC_ACE *ace, const NT_USER_TOKEN *token, uint32 acc_desired,
  31                         NTSTATUS *status)
  32 {
  33         uint32 mask = ace->access_mask;
  34
  35         /*
  36          * Inherit only is ignored.
  37          */
  38
  39         if (ace->flags & SEC_ACE_FLAG_INHERIT_ONLY) {
  40                 return acc_desired;
  41         }
  42
  43         /*
  44          * If this ACE has no SID in common with the token,
  45          * ignore it as it cannot be used to make an access
  46          * determination.
  47          */
  48
  49         if (!token_sid_in_ace( token, ace))
  50                 return acc_desired;
  51
  52         switch (ace->type) {
  53                 case SEC_ACE_TYPE_ACCESS_ALLOWED:
  54                         /*
  55                          * This is explicitly allowed.
  56                          * Remove the bits from the remaining
  57                          * access required. Return the remaining
  58                          * bits needed.
  59                          */
  60                         acc_desired &= ~mask;
  61                         break;
  62                 case SEC_ACE_TYPE_ACCESS_DENIED:
  63                         /*
  64                          * This is explicitly denied.
  65                          * If any bits match terminate here,
  66                          * we are denied.
  67                          */
  68                         if (acc_desired & mask) {
  69                                 *status = NT_STATUS_ACCESS_DENIED;
  70                                 return 0xFFFFFFFF;
  71                         }
  72                         break;
  73                 case SEC_ACE_TYPE_SYSTEM_ALARM:
  74                 case SEC_ACE_TYPE_SYSTEM_AUDIT:
  75                         *status = NT_STATUS_NOT_IMPLEMENTED;
  76                         return 0xFFFFFFFF;
  77                 default:
  78                         *status = NT_STATUS_INVALID_PARAMETER;
  79                         return 0xFFFFFFFF;
  80         }
  81
  82         return acc_desired;
  83 }
  84
  85 /*********************************************************************************
  86  Maximum access was requested. Calculate the max possible. Fail if it doesn't
  87  include other bits requested.
  88 **********************************************************************************/
  89
  90 static bool get_max_access( SEC_ACL *the_acl, const NT_USER_TOKEN *token, uint32 *granted,
  91                             uint32 desired,
  92                             NTSTATUS *status)
  93 {
  94         uint32 acc_denied = 0;
  95         uint32 acc_granted = 0;
  96         size_t i;
  97
  98         for ( i = 0 ; i < the_acl->num_aces; i++) {
  99                 SEC_ACE *ace = &the_acl->aces[i];
 100                 uint32 mask = ace->access_mask;
 101
 102                 if (!token_sid_in_ace( token, ace))
 103                         continue;
 104
 105                 switch (ace->type) {
 106                         case SEC_ACE_TYPE_ACCESS_ALLOWED:
 107                                 acc_granted |= (mask & ~acc_denied);
 108                                 break;
 109                         case SEC_ACE_TYPE_ACCESS_DENIED:
 110                                 acc_denied |= (mask & ~acc_granted);
 111                                 break;
 112                         case SEC_ACE_TYPE_SYSTEM_ALARM:
 113                         case SEC_ACE_TYPE_SYSTEM_AUDIT:
 114                                 *status = NT_STATUS_NOT_IMPLEMENTED;
 115                                 *granted = 0;
 116                                 return False;
 117                         default:
 118                                 *status = NT_STATUS_INVALID_PARAMETER;
 119                                 *granted = 0;
 120                                 return False;
 121                 }
 122         }
 123
 124         /*
 125          * If we were granted no access, or we desired bits that we
 126          * didn't get, then deny.
 127          */
 128
 129         if ((acc_granted == 0) || ((acc_granted & desired) != desired)) {
 130                 *status = NT_STATUS_ACCESS_DENIED;
 131                 *granted = 0;
 132                 return False;
 133         }
 134
 135         /*
 136          * Return the access we did get.
 137          */
 138
 139         *granted = acc_granted;
 140         *status = NT_STATUS_OK;
 141         return True;
 142 }
 143
 144 /* Map generic access rights to object specific rights.  This technique is
 145    used to give meaning to assigning read, write, execute and all access to
 146    objects.  Each type of object has its own mapping of generic to object
 147    specific access rights. */
 148
 149 void se_map_generic(uint32 *access_mask, const struct generic_mapping *mapping)
 150 {
 151         uint32 old_mask = *access_mask;
 152
 153         if (*access_mask & GENERIC_READ_ACCESS) {
 154                 *access_mask &= ~GENERIC_READ_ACCESS;
 155                 *access_mask |= mapping->generic_read;
 156         }
 157
 158         if (*access_mask & GENERIC_WRITE_ACCESS) {
 159                 *access_mask &= ~GENERIC_WRITE_ACCESS;
 160                 *access_mask |= mapping->generic_write;
 161         }
 162
 163         if (*access_mask & GENERIC_EXECUTE_ACCESS) {
 164                 *access_mask &= ~GENERIC_EXECUTE_ACCESS;
 165                 *access_mask |= mapping->generic_execute;
 166         }
 167
 168         if (*access_mask & GENERIC_ALL_ACCESS) {
 169                 *access_mask &= ~GENERIC_ALL_ACCESS;
 170                 *access_mask |= mapping->generic_all;
 171         }
 172
 173         if (old_mask != *access_mask) {
 174                 DEBUG(10, ("se_map_generic(): mapped mask 0x%08x to 0x%08x\n",
 175                            old_mask, *access_mask));
 176         }
 177 }
 178
 179 /* Map standard access rights to object specific rights.  This technique is
 180    used to give meaning to assigning read, write, execute and all access to
 181    objects.  Each type of object has its own mapping of standard to object
 182    specific access rights. */
 183
 184 void se_map_standard(uint32 *access_mask, struct standard_mapping *mapping)
 185 {
 186         uint32 old_mask = *access_mask;
 187
 188         if (*access_mask & READ_CONTROL_ACCESS) {
 189                 *access_mask &= ~READ_CONTROL_ACCESS;
 190                 *access_mask |= mapping->std_read;
 191         }
 192
 193         if (*access_mask & (DELETE_ACCESS|WRITE_DAC_ACCESS|WRITE_OWNER_ACCESS|SYNCHRONIZE_ACCESS)) {
 194                 *access_mask &= ~(DELETE_ACCESS|WRITE_DAC_ACCESS|WRITE_OWNER_ACCESS|SYNCHRONIZE_ACCESS);
 195                 *access_mask |= mapping->std_all;
 196         }
 197
 198         if (old_mask != *access_mask) {
 199                 DEBUG(10, ("se_map_standard(): mapped mask 0x%08x to 0x%08x\n",
 200                            old_mask, *access_mask));
 201         }
 202 }
 203
 204 /*****************************************************************************
 205  Check access rights of a user against a security descriptor.  Look at
 206  each ACE in the security descriptor until an access denied ACE denies
 207  any of the desired rights to the user or any of the users groups, or one
 208  or more ACEs explicitly grant all requested access rights.  See
 209  "Access-Checking" document in MSDN.
 210 *****************************************************************************/
 211
 212 bool se_access_check(const SEC_DESC *sd, const NT_USER_TOKEN *token,
 213                      uint32 acc_desired, uint32 *acc_granted,
 214                      NTSTATUS *status)
 215 {
 216         size_t i;
 217         SEC_ACL *the_acl;
 218         uint32 tmp_acc_desired = acc_desired;
 219
 220         if (!status || !acc_granted)
 221                 return False;
 222
 223         if (!token)
 224                 token = &anonymous_token;
 225
 226         *status = NT_STATUS_OK;
 227         *acc_granted = 0;
 228
 229         DEBUG(10,("se_access_check: requested access 0x%08x, for NT token "
 230                   "with %u entries and first sid %s.\n",
 231                   (unsigned int)acc_desired, (unsigned int)token->num_sids,
 232                   sid_string_dbg(&token->user_sids[0])));
 233
 234         /*
 235          * No security descriptor or security descriptor with no DACL
 236          * present allows all access.
 237          */
 238
 239         /* ACL must have something in it */
 240
 241         if (!sd || (sd && (!(sd->type & SEC_DESC_DACL_PRESENT) || sd->dacl == NULL))) {
 242                 *status = NT_STATUS_OK;
 243                 *acc_granted = acc_desired;
 244                 DEBUG(5, ("se_access_check: no sd or blank DACL, access allowed\n"));
 245                 return True;
 246         }
 247
 248         /* The user sid is the first in the token */
 249         if (DEBUGLVL(3)) {
 250                 DEBUG(3, ("se_access_check: user sid is %s\n",
 251                           sid_string_dbg(
 252                                   &token->user_sids[PRIMARY_USER_SID_INDEX])));
 253
 254                 for (i = 1; i < token->num_sids; i++) {
 255                         DEBUGADD(3, ("se_access_check: also %s\n",
 256                                      sid_string_dbg(&token->user_sids[i])));
 257                 }
 258         }
 259
 260         /* Is the token the owner of the SID ? */
 261
 262         if (sd->owner_sid) {
 263                 for (i = 0; i < token->num_sids; i++) {
 264                         if (sid_equal(&token->user_sids[i], sd->owner_sid)) {
 265                                 /*
 266                                  * The owner always has SEC_RIGHTS_WRITE_DAC & READ_CONTROL.
 267                                  */
 268                                 if (tmp_acc_desired & WRITE_DAC_ACCESS)
 269                                         tmp_acc_desired &= ~WRITE_DAC_ACCESS;
 270                                 if (tmp_acc_desired & READ_CONTROL_ACCESS)
 271                                         tmp_acc_desired &= ~READ_CONTROL_ACCESS;
 272                         }
 273                 }
 274         }
 275
 276         the_acl = sd->dacl;
 277
 278         if (tmp_acc_desired & MAXIMUM_ALLOWED_ACCESS) {
 279                 tmp_acc_desired &= ~MAXIMUM_ALLOWED_ACCESS;
 280                 return get_max_access( the_acl, token, acc_granted, tmp_acc_desired,
 281                                        status);
 282         }
 283
 284         for ( i = 0 ; i < the_acl->num_aces && tmp_acc_desired != 0; i++) {
 285                 SEC_ACE *ace = &the_acl->aces[i];
 286
 287                 DEBUGADD(10,("se_access_check: ACE %u: type %d, flags = "
 288                              "0x%02x, SID = %s mask = %x, current desired "
 289                              "= %x\n", (unsigned int)i, ace->type, ace->flags,
 290                              sid_string_dbg(&ace->trustee),
 291                              (unsigned int) ace->access_mask,
 292                              (unsigned int)tmp_acc_desired ));
 293
 294                 tmp_acc_desired = check_ace( ace, token, tmp_acc_desired, status);
 295                 if (NT_STATUS_V(*status)) {
 296                         *acc_granted = 0;
 297                         DEBUG(5,("se_access_check: ACE %u denied with status %s.\n", (unsigned int)i, nt_errstr(*status)));
 298                         return False;
 299                 }
 300         }
 301
 302         /*
 303          * If there are no more desired permissions left then
 304          * access was allowed.
 305          */
 306
 307         if (tmp_acc_desired == 0) {
 308                 *acc_granted = acc_desired;
 309                 *status = NT_STATUS_OK;
 310                 DEBUG(5,("se_access_check: access (%x) granted.\n", (unsigned int)acc_desired ));
 311                 return True;
 312         }
 313
 314         *acc_granted = 0;
 315         *status = NT_STATUS_ACCESS_DENIED;
 316         DEBUG(5,("se_access_check: access (%x) denied.\n", (unsigned int)acc_desired ));
 317         return False;
 318 }
 319
 320
 321 /*******************************************************************
 322  samr_make_sam_obj_sd
 323  ********************************************************************/
 324
 325 NTSTATUS samr_make_sam_obj_sd(TALLOC_CTX *ctx, SEC_DESC **psd, size_t *sd_size)
 326 {
 327         DOM_SID adm_sid;
 328         DOM_SID act_sid;
 329
 330         SEC_ACE ace[3];
 331         SEC_ACCESS mask;
 332
 333         SEC_ACL *psa = NULL;
 334
 335         sid_copy(&adm_sid, &global_sid_Builtin);
 336         sid_append_rid(&adm_sid, BUILTIN_ALIAS_RID_ADMINS);
 337
 338         sid_copy(&act_sid, &global_sid_Builtin);
 339         sid_append_rid(&act_sid, BUILTIN_ALIAS_RID_ACCOUNT_OPS);
 340
 341         /*basic access for every one*/
 342         init_sec_access(&mask, GENERIC_RIGHTS_SAM_EXECUTE | GENERIC_RIGHTS_SAM_READ);
 343         init_sec_ace(&ace[0], &global_sid_World, SEC_ACE_TYPE_ACCESS_ALLOWED, mask, 0);
 344
 345         /*full access for builtin aliases Administrators and Account Operators*/
 346         init_sec_access(&mask, GENERIC_RIGHTS_SAM_ALL_ACCESS);
 347         init_sec_ace(&ace[1], &adm_sid, SEC_ACE_TYPE_ACCESS_ALLOWED, mask, 0);
 348         init_sec_ace(&ace[2], &act_sid, SEC_ACE_TYPE_ACCESS_ALLOWED, mask, 0);
 349
 350         if ((psa = make_sec_acl(ctx, NT4_ACL_REVISION, 3, ace)) == NULL)
 351                 return NT_STATUS_NO_MEMORY;
 352
 353         if ((*psd = make_sec_desc(ctx, SECURITY_DESCRIPTOR_REVISION_1,
 354                                   SEC_DESC_SELF_RELATIVE, NULL, NULL, NULL,
 355                                   psa, sd_size)) == NULL)
 356                 return NT_STATUS_NO_MEMORY;
 357
 358         return NT_STATUS_OK;
 359 }