libcli/security/create_descriptor.c

   1 /*
   2    Copyright (C) Nadezhda Ivanova 2009
   3
   4    This program is free software; you can redistribute it and/or modify
   5    it under the terms of the GNU General Public License as published by
   6    the Free Software Foundation; either version 3 of the License, or
   7    (at your option) any later version.
   8
   9    This program is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12    GNU General Public License for more details.
  13
  14    You should have received a copy of the GNU General Public License
  15    along with this program.  If not, see <http://www.gnu.org/licenses/>.
  16 */
  17
  18 /*
  19  *  Name: create_descriptor
  20  *
  21  *  Component: routines for calculating and creating security descriptors
  22  *  as described in MS-DTYP 2.5.3.x
  23  *
  24  *  Description:
  25  *
  26  *
  27  *  Author: Nadezhda Ivanova
  28  */
  29 #include "includes.h"
  30 #include "libcli/security/security.h"
  31 #include "librpc/gen_ndr/ndr_security.h"
  32
  33 /* Todos:
  34  * build the security token dacl as follows:
  35  * SYSTEM: GA, OWNER: GA, LOGIN_SID:GW|GE
  36  * Need session id information for the login SID. Probably
  37  * the best place for this is during token creation
  38  *
  39  * Implement SD Invariants
  40  * ACE sorting rules
  41  * LDAP_SERVER_SD_FLAGS_OID control
  42  * ADTS 7.1.3.3 needs to be clarified
  43  */
  44
  45 /* the mapping function for generic rights for DS.(GA,GR,GW,GX)
  46  * The mapping function is passed as an argument to the
  47  * descriptor calculating routine and depends on the security
  48  * manager that calls the calculating routine.
  49  * TODO: need similar mappings for the file system and
  50  * registry security managers in order to make this code
  51  * generic for all security managers
  52  */
  53
  54 uint32_t map_generic_rights_ds(uint32_t access_mask)
  55 {
  56         if (access_mask & SEC_GENERIC_ALL) {
  57                 access_mask |= SEC_ADS_GENERIC_ALL;
  58                 access_mask &= ~SEC_GENERIC_ALL;
  59         }
  60
  61         if (access_mask & SEC_GENERIC_EXECUTE) {
  62                 access_mask |= SEC_ADS_GENERIC_EXECUTE;
  63                 access_mask &= ~SEC_GENERIC_EXECUTE;
  64         }
  65
  66         if (access_mask & SEC_GENERIC_WRITE) {
  67                 access_mask |= SEC_ADS_GENERIC_WRITE;
  68                 access_mask &= ~SEC_GENERIC_WRITE;
  69         }
  70
  71         if (access_mask & SEC_GENERIC_READ) {
  72                 access_mask |= SEC_ADS_GENERIC_READ;
  73                 access_mask &= ~SEC_GENERIC_READ;
  74         }
  75
  76         return access_mask;
  77 }
  78
  79 /* Not sure what this has to be,
  80 * and it does not seem to have any influence */
  81 static bool object_in_list(struct GUID *object_list, struct GUID *object)
  82 {
  83         size_t i;
  84
  85         if (object_list == NULL) {
  86                 return true;
  87         }
  88
  89         if (GUID_all_zero(object)) {
  90                 return true;
  91         }
  92
  93         for (i=0; ; i++) {
  94                 if (GUID_all_zero(&object_list[i])) {
  95                         return false;
  96                 }
  97                 if (!GUID_equal(&object_list[i], object)) {
  98                         continue;
  99                 }
 100
 101                 return true;
 102         }
 103
 104         return false;
 105 }
 106
 107 /* returns true if the ACE gontains generic information
 108  * that needs to be processed additionally */
 109
 110 static bool desc_ace_has_generic(struct security_ace *ace)
 111 {
 112         if (ace->access_mask & SEC_GENERIC_ALL || ace->access_mask & SEC_GENERIC_READ ||
 113             ace->access_mask & SEC_GENERIC_WRITE || ace->access_mask & SEC_GENERIC_EXECUTE) {
 114                 return true;
 115         }
 116         if (dom_sid_equal(&ace->trustee, &global_sid_Creator_Owner) ||
 117             dom_sid_equal(&ace->trustee, &global_sid_Creator_Group)) {
 118                 return true;
 119         }
 120         return false;
 121 }
 122
 123 /* creates an ace in which the generic information is expanded */
 124
 125 static void desc_expand_generic(struct security_ace *new_ace,
 126                                 struct dom_sid *owner,
 127                                 struct dom_sid *group)
 128 {
 129         new_ace->access_mask = map_generic_rights_ds(new_ace->access_mask);
 130         if (dom_sid_equal(&new_ace->trustee, &global_sid_Creator_Owner)) {
 131                 new_ace->trustee = *owner;
 132         }
 133         if (dom_sid_equal(&new_ace->trustee, &global_sid_Creator_Group)) {
 134                 new_ace->trustee = *group;
 135         }
 136         new_ace->flags = 0x0;
 137 }
 138
 139 static struct security_acl *calculate_inherited_from_parent(TALLOC_CTX *mem_ctx,
 140                                                             struct security_acl *acl,
 141                                                             bool is_container,
 142                                                             struct dom_sid *owner,
 143                                                             struct dom_sid *group,
 144                                                             struct GUID *object_list)
 145 {
 146         uint32_t i;
 147         TALLOC_CTX *tmp_ctx = talloc_new(mem_ctx);
 148         struct security_acl *tmp_acl = talloc_zero(mem_ctx, struct security_acl);
 149         if (!tmp_acl) {
 150                 return NULL;
 151         }
 152
 153         if (!acl) {
 154                 return NULL;
 155         }
 156
 157         for (i=0; i < acl->num_aces; i++) {
 158                 struct security_ace *ace = &acl->aces[i];
 159                 if ((ace->flags & SEC_ACE_FLAG_CONTAINER_INHERIT) ||
 160                     (ace->flags & SEC_ACE_FLAG_OBJECT_INHERIT)) {
 161                         struct GUID inherited_object = GUID_zero();
 162
 163                         tmp_acl->aces = talloc_realloc(tmp_acl, tmp_acl->aces,
 164                                                        struct security_ace,
 165                                                        tmp_acl->num_aces+1);
 166                         if (tmp_acl->aces == NULL) {
 167                                 talloc_free(tmp_ctx);
 168                                 return NULL;
 169                         }
 170
 171                         tmp_acl->aces[tmp_acl->num_aces] = *ace;
 172                         tmp_acl->aces[tmp_acl->num_aces].flags |= SEC_ACE_FLAG_INHERITED_ACE;
 173                         /* remove IO flag from the child's ace */
 174                         if (ace->flags & SEC_ACE_FLAG_INHERIT_ONLY &&
 175                             !desc_ace_has_generic(ace)) {
 176                                 tmp_acl->aces[tmp_acl->num_aces].flags &= ~SEC_ACE_FLAG_INHERIT_ONLY;
 177                         }
 178
 179                         if (is_container && (ace->flags & SEC_ACE_FLAG_OBJECT_INHERIT))
 180                             tmp_acl->aces[tmp_acl->num_aces].flags |= SEC_ACE_FLAG_INHERIT_ONLY;
 181
 182                         switch (ace->type) {
 183                         case SEC_ACE_TYPE_ACCESS_ALLOWED:
 184                         case SEC_ACE_TYPE_ACCESS_DENIED:
 185                         case SEC_ACE_TYPE_SYSTEM_AUDIT:
 186                         case SEC_ACE_TYPE_SYSTEM_ALARM:
 187                         case SEC_ACE_TYPE_ALLOWED_COMPOUND:
 188                                 break;
 189
 190                         case SEC_ACE_TYPE_ACCESS_ALLOWED_OBJECT:
 191                         case SEC_ACE_TYPE_ACCESS_DENIED_OBJECT:
 192                         case SEC_ACE_TYPE_SYSTEM_ALARM_OBJECT:
 193                         case SEC_ACE_TYPE_SYSTEM_AUDIT_OBJECT:
 194                                 if (ace->object.object.flags & SEC_ACE_INHERITED_OBJECT_TYPE_PRESENT) {
 195                                         inherited_object = ace->object.object.inherited_type.inherited_type;
 196                                 }
 197
 198                                 if (!object_in_list(object_list, &inherited_object)) {
 199                                         tmp_acl->aces[tmp_acl->num_aces].flags |= SEC_ACE_FLAG_INHERIT_ONLY;
 200                                 }
 201
 202                                 break;
 203                         }
 204
 205                         tmp_acl->num_aces++;
 206                         if (is_container) {
 207                                 if (!(ace->flags & SEC_ACE_FLAG_NO_PROPAGATE_INHERIT) &&
 208                                     (desc_ace_has_generic(ace))) {
 209                                             tmp_acl->aces = talloc_realloc(tmp_acl,
 210                                                                            tmp_acl->aces,
 211                                                                            struct security_ace,
 212                                                                            tmp_acl->num_aces+1);
 213                                             if (tmp_acl->aces == NULL) {
 214                                                     talloc_free(tmp_ctx);
 215                                                     return NULL;
 216                                             }
 217                                             tmp_acl->aces[tmp_acl->num_aces] = *ace;
 218                                             desc_expand_generic(&tmp_acl->aces[tmp_acl->num_aces],
 219                                                                 owner,
 220                                                                 group);
 221                                             tmp_acl->aces[tmp_acl->num_aces].flags = SEC_ACE_FLAG_INHERITED_ACE;
 222                                             tmp_acl->num_aces++;
 223                                 }
 224                         }
 225                 }
 226         }
 227         if (tmp_acl->num_aces == 0) {
 228                 return NULL;
 229         }
 230         if (acl) {
 231                 tmp_acl->revision = acl->revision;
 232         }
 233         return tmp_acl;
 234 }
 235
 236 static struct security_acl *process_user_acl(TALLOC_CTX *mem_ctx,
 237                                              struct security_acl *acl,
 238                                              bool is_container,
 239                                              struct dom_sid *owner,
 240                                              struct dom_sid *group,
 241                                              struct GUID *object_list,
 242                                              bool is_protected)
 243 {
 244         uint32_t i;
 245         TALLOC_CTX *tmp_ctx = talloc_new(mem_ctx);
 246         struct security_acl *tmp_acl = talloc_zero(tmp_ctx, struct security_acl);
 247         struct security_acl *new_acl;
 248
 249         if (!acl)
 250                 return NULL;
 251
 252         if (!tmp_acl)
 253                 return NULL;
 254
 255         tmp_acl->revision = acl->revision;
 256         DEBUG(6,(__location__ ": acl revision %d\n", acl->revision));
 257
 258         for (i=0; i < acl->num_aces; i++){
 259                 struct security_ace *ace = &acl->aces[i];
 260                 /* Remove ID flags from user-provided ACEs
 261                  * if we break inheritance, ignore them otherwise */
 262                 if (ace->flags & SEC_ACE_FLAG_INHERITED_ACE) {
 263                         if (is_protected) {
 264                                 ace->flags &= ~SEC_ACE_FLAG_INHERITED_ACE;
 265                         } else {
 266                                 continue;
 267                         }
 268                 }
 269
 270                 if (ace->flags & SEC_ACE_FLAG_INHERIT_ONLY &&
 271                     !(ace->flags & SEC_ACE_FLAG_CONTAINER_INHERIT ||
 272                       ace->flags & SEC_ACE_FLAG_OBJECT_INHERIT))
 273                         continue;
 274
 275                 tmp_acl->aces = talloc_realloc(tmp_acl,
 276                                                tmp_acl->aces,
 277                                                struct security_ace,
 278                                                tmp_acl->num_aces+1);
 279                 tmp_acl->aces[tmp_acl->num_aces] = *ace;
 280                 tmp_acl->num_aces++;
 281                 if (ace->flags & SEC_ACE_FLAG_INHERIT_ONLY) {
 282                         continue;
 283                 }
 284                 /* if the ACE contains CO, CG, GA, GE, GR or GW, and is inheritable
 285                  * it has to be expanded to two aces, the original as IO,
 286                  * and another one where these are translated */
 287                 if (desc_ace_has_generic(ace)) {
 288                         if (!(ace->flags & SEC_ACE_FLAG_CONTAINER_INHERIT)) {
 289                                 desc_expand_generic(&tmp_acl->aces[tmp_acl->num_aces-1],
 290                                                     owner,
 291                                                     group);
 292                         } else {
 293                                 /*The original ACE becomes read only */
 294                                 tmp_acl->aces[tmp_acl->num_aces-1].flags |= SEC_ACE_FLAG_INHERIT_ONLY;
 295                                 tmp_acl->aces = talloc_realloc(tmp_acl, tmp_acl->aces,
 296                                                                struct security_ace,
 297                                                                tmp_acl->num_aces+1);
 298                                 /* add a new ACE with expanded generic info */
 299                                 tmp_acl->aces[tmp_acl->num_aces] = *ace;
 300                                 desc_expand_generic(&tmp_acl->aces[tmp_acl->num_aces],
 301                                                     owner,
 302                                                     group);
 303                                 tmp_acl->num_aces++;
 304                         }
 305                 }
 306         }
 307         new_acl = security_acl_dup(mem_ctx,tmp_acl);
 308
 309         if (new_acl)
 310                 new_acl->revision = acl->revision;
 311
 312         talloc_free(tmp_ctx);
 313         return new_acl;
 314 }
 315
 316 static void cr_descr_log_descriptor(struct security_descriptor *sd,
 317                                     const char *message,
 318                                     int level)
 319 {
 320         if (sd) {
 321                 DEBUG(level,("%s: %s\n", message,
 322                              ndr_print_struct_string(0,(ndr_print_fn_t)ndr_print_security_descriptor,
 323                                                      "", sd)));
 324         }
 325         else {
 326                 DEBUG(level,("%s: NULL\n", message));
 327         }
 328 }
 329
 330 #if 0
 331 static void cr_descr_log_acl(struct security_acl *acl,
 332                                     const char *message,
 333                                     int level)
 334 {
 335         if (acl) {
 336                 DEBUG(level,("%s: %s\n", message,
 337                              ndr_print_struct_string(0,(ndr_print_fn_t)ndr_print_security_acl,
 338                                                      "", acl)));
 339         }
 340         else {
 341                 DEBUG(level,("%s: NULL\n", message));
 342         }
 343 }
 344 #endif
 345
 346 static bool compute_acl(struct security_descriptor *parent_sd,
 347                         struct security_descriptor *creator_sd,
 348                         bool is_container,
 349                         uint32_t inherit_flags,
 350                         struct GUID *object_list,
 351                         uint32_t (*generic_map)(uint32_t access_mask),
 352                         struct security_token *token,
 353                         struct security_descriptor *new_sd) /* INOUT argument */
 354 {
 355         struct security_acl *user_dacl, *user_sacl, *inherited_dacl, *inherited_sacl;
 356         int level = 10;
 357
 358         if (!parent_sd || !(inherit_flags & SEC_DACL_AUTO_INHERIT)) {
 359                 inherited_dacl = NULL;
 360         } else if (creator_sd && (creator_sd->type & SEC_DESC_DACL_PROTECTED)) {
 361                 inherited_dacl = NULL;
 362         } else {
 363                 inherited_dacl = calculate_inherited_from_parent(new_sd,
 364                                                                  parent_sd->dacl,
 365                                                                  is_container,
 366                                                                  new_sd->owner_sid,
 367                                                                  new_sd->group_sid,
 368                                                                  object_list);
 369         }
 370
 371
 372         if (!parent_sd || !(inherit_flags & SEC_SACL_AUTO_INHERIT)) {
 373                 inherited_sacl = NULL;
 374         } else if (creator_sd && (creator_sd->type & SEC_DESC_SACL_PROTECTED)) {
 375                 inherited_sacl = NULL;
 376         } else {
 377                 inherited_sacl = calculate_inherited_from_parent(new_sd,
 378                                                                  parent_sd->sacl,
 379                                                                  is_container,
 380                                                                  new_sd->owner_sid,
 381                                                                  new_sd->group_sid,
 382                                                                  object_list);
 383         }
 384
 385         if (!creator_sd || (inherit_flags & SEC_DEFAULT_DESCRIPTOR)) {
 386                 user_dacl = NULL;
 387                 user_sacl = NULL;
 388         } else {
 389                 user_dacl = process_user_acl(new_sd,
 390                                              creator_sd->dacl,
 391                                              is_container,
 392                                              new_sd->owner_sid,
 393                                              new_sd->group_sid,
 394                                              object_list,
 395                                              creator_sd->type & SEC_DESC_DACL_PROTECTED);
 396                 user_sacl = process_user_acl(new_sd,
 397                                              creator_sd->sacl,
 398                                              is_container,
 399                                              new_sd->owner_sid,
 400                                              new_sd->group_sid,
 401                                              object_list,
 402                                              creator_sd->type & SEC_DESC_SACL_PROTECTED);
 403         }
 404         cr_descr_log_descriptor(parent_sd, __location__"parent_sd", level);
 405         cr_descr_log_descriptor(creator_sd,__location__ "creator_sd", level);
 406
 407         new_sd->dacl = security_acl_concatenate(new_sd, user_dacl, inherited_dacl);
 408         if (new_sd->dacl) {
 409                 new_sd->type |= SEC_DESC_DACL_PRESENT;
 410         }
 411         if (inherited_dacl) {
 412                 new_sd->type |= SEC_DESC_DACL_AUTO_INHERITED;
 413         }
 414
 415         new_sd->sacl = security_acl_concatenate(new_sd, user_sacl, inherited_sacl);
 416         if (new_sd->sacl) {
 417                 new_sd->type |= SEC_DESC_SACL_PRESENT;
 418         }
 419         if (inherited_sacl) {
 420                 new_sd->type |= SEC_DESC_SACL_AUTO_INHERITED;
 421         }
 422         /* This is a hack to handle the fact that
 423          * apprantly any AI flag provided by the user is preserved */
 424         if (creator_sd)
 425                 new_sd->type |= creator_sd->type;
 426         cr_descr_log_descriptor(new_sd, __location__"final sd", level);
 427         return true;
 428 }
 429
 430 struct security_descriptor *create_security_descriptor(TALLOC_CTX *mem_ctx,
 431                                                        struct security_descriptor *parent_sd,
 432                                                        struct security_descriptor *creator_sd,
 433                                                        bool is_container,
 434                                                        struct GUID *object_list,
 435                                                        uint32_t inherit_flags,
 436                                                        struct security_token *token,
 437                                                        struct dom_sid *default_owner, /* valid only for DS, NULL for the other RSs */
 438                                                        struct dom_sid *default_group, /* valid only for DS, NULL for the other RSs */
 439                                                        uint32_t (*generic_map)(uint32_t access_mask))
 440 {
 441         struct security_descriptor *new_sd;
 442         struct dom_sid *new_owner = NULL;
 443         struct dom_sid *new_group = NULL;
 444
 445         new_sd = security_descriptor_initialise(mem_ctx);
 446         if (!new_sd) {
 447                 return NULL;
 448         }
 449
 450         if (!creator_sd || !creator_sd->owner_sid) {
 451                 if ((inherit_flags & SEC_OWNER_FROM_PARENT) && parent_sd) {
 452                         new_owner = parent_sd->owner_sid;
 453                 } else if (!default_owner) {
 454                         new_owner = &token->sids[PRIMARY_USER_SID_INDEX];
 455                 } else {
 456                         new_owner = default_owner;
 457                         new_sd->type |= SEC_DESC_OWNER_DEFAULTED;
 458                 }
 459         } else {
 460                 new_owner = creator_sd->owner_sid;
 461         }
 462
 463         if (!creator_sd || !creator_sd->group_sid){
 464                 if ((inherit_flags & SEC_GROUP_FROM_PARENT) && parent_sd) {
 465                         new_group = parent_sd->group_sid;
 466                 } else if (!default_group && token->num_sids > PRIMARY_GROUP_SID_INDEX) {
 467                         new_group = &token->sids[PRIMARY_GROUP_SID_INDEX];
 468                 } else if (!default_group) {
 469                         /* This will happen only for anonymous, which has no other groups */
 470                         new_group = &token->sids[PRIMARY_USER_SID_INDEX];
 471                 } else {
 472                         new_group = default_group;
 473                         new_sd->type |= SEC_DESC_GROUP_DEFAULTED;
 474                 }
 475         } else {
 476                 new_group = creator_sd->group_sid;
 477         }
 478
 479         new_sd->owner_sid = talloc_memdup(new_sd, new_owner, sizeof(struct dom_sid));
 480         new_sd->group_sid = talloc_memdup(new_sd, new_group, sizeof(struct dom_sid));
 481         if (!new_sd->owner_sid || !new_sd->group_sid){
 482                 talloc_free(new_sd);
 483                 return NULL;
 484         }
 485
 486         if (!compute_acl(parent_sd, creator_sd,
 487                          is_container, inherit_flags, object_list,
 488                          generic_map,token,new_sd)){
 489                 talloc_free(new_sd);
 490                 return NULL;
 491         }
 492
 493         return new_sd;
 494 }