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(TALLOC_CTX *mem_ctx,
 111                              struct security_ace *ace)
 112 {
 113         struct dom_sid *co, *cg;
 114         co = dom_sid_parse_talloc(mem_ctx,  SID_CREATOR_OWNER);
 115         cg = dom_sid_parse_talloc(mem_ctx,  SID_CREATOR_GROUP);
 116         if (ace->access_mask & SEC_GENERIC_ALL || ace->access_mask & SEC_GENERIC_READ ||
 117             ace->access_mask & SEC_GENERIC_WRITE || ace->access_mask & SEC_GENERIC_EXECUTE) {
 118                 return true;
 119         }
 120         if (dom_sid_equal(&ace->trustee, co) || dom_sid_equal(&ace->trustee, cg)) {
 121                 return true;
 122         }
 123         return false;
 124 }
 125
 126 /* creates an ace in which the generic information is expanded */
 127
 128 static void desc_expand_generic(TALLOC_CTX *mem_ctx,
 129                                 struct security_ace *new_ace,
 130                                 struct dom_sid *owner,
 131                                 struct dom_sid *group)
 132 {
 133         struct dom_sid *co, *cg;
 134         co = dom_sid_parse_talloc(mem_ctx,  SID_CREATOR_OWNER);
 135         cg = dom_sid_parse_talloc(mem_ctx,  SID_CREATOR_GROUP);
 136         new_ace->access_mask = map_generic_rights_ds(new_ace->access_mask);
 137         if (dom_sid_equal(&new_ace->trustee, co)) {
 138                 new_ace->trustee = *owner;
 139         }
 140         if (dom_sid_equal(&new_ace->trustee, cg)) {
 141                 new_ace->trustee = *group;
 142         }
 143         new_ace->flags = 0x0;
 144 }
 145
 146 static struct security_acl *calculate_inherited_from_parent(TALLOC_CTX *mem_ctx,
 147                                                             struct security_acl *acl,
 148                                                             bool is_container,
 149                                                             struct dom_sid *owner,
 150                                                             struct dom_sid *group,
 151                                                             struct GUID *object_list)
 152 {
 153         uint32_t i;
 154         TALLOC_CTX *tmp_ctx = talloc_new(mem_ctx);
 155         struct security_acl *tmp_acl = talloc_zero(mem_ctx, struct security_acl);
 156         if (!tmp_acl) {
 157                 return NULL;
 158         }
 159
 160         if (!acl) {
 161                 return NULL;
 162         }
 163
 164         for (i=0; i < acl->num_aces; i++) {
 165                 struct security_ace *ace = &acl->aces[i];
 166                 if ((ace->flags & SEC_ACE_FLAG_CONTAINER_INHERIT) ||
 167                     (ace->flags & SEC_ACE_FLAG_OBJECT_INHERIT)) {
 168                         tmp_acl->aces = talloc_realloc(tmp_acl, tmp_acl->aces,
 169                                                        struct security_ace,
 170                                                        tmp_acl->num_aces+1);
 171                         if (tmp_acl->aces == NULL) {
 172                                 talloc_free(tmp_ctx);
 173                                 return NULL;
 174                         }
 175
 176                         tmp_acl->aces[tmp_acl->num_aces] = *ace;
 177                         tmp_acl->aces[tmp_acl->num_aces].flags |= SEC_ACE_FLAG_INHERITED_ACE;
 178                         /* remove IO flag from the child's ace */
 179                         if (ace->flags & SEC_ACE_FLAG_INHERIT_ONLY &&
 180                             !desc_ace_has_generic(tmp_ctx, ace)) {
 181                                 tmp_acl->aces[tmp_acl->num_aces].flags &= ~SEC_ACE_FLAG_INHERIT_ONLY;
 182                         }
 183
 184                         if (is_container && (ace->flags & SEC_ACE_FLAG_OBJECT_INHERIT))
 185                             tmp_acl->aces[tmp_acl->num_aces].flags |= SEC_ACE_FLAG_INHERIT_ONLY;
 186
 187                         if (ace->type == SEC_ACE_TYPE_ACCESS_ALLOWED_OBJECT ||
 188                             ace->type == SEC_ACE_TYPE_ACCESS_DENIED_OBJECT) {
 189                                 struct GUID inherited_object = GUID_zero();
 190
 191                                 if (ace->object.object.flags & SEC_ACE_INHERITED_OBJECT_TYPE_PRESENT) {
 192                                         inherited_object = ace->object.object.inherited_type.inherited_type;
 193                                 }
 194
 195                                 if (!object_in_list(object_list, &inherited_object)) {
 196                                         tmp_acl->aces[tmp_acl->num_aces].flags |= SEC_ACE_FLAG_INHERIT_ONLY;
 197                                 }
 198
 199                         }
 200                         tmp_acl->num_aces++;
 201                         if (is_container) {
 202                                 if (!(ace->flags & SEC_ACE_FLAG_NO_PROPAGATE_INHERIT) &&
 203                                     (desc_ace_has_generic(tmp_ctx, ace))) {
 204                                             tmp_acl->aces = talloc_realloc(tmp_acl,
 205                                                                            tmp_acl->aces,
 206                                                                            struct security_ace,
 207                                                                            tmp_acl->num_aces+1);
 208                                             if (tmp_acl->aces == NULL) {
 209                                                     talloc_free(tmp_ctx);
 210                                                     return NULL;
 211                                             }
 212                                             tmp_acl->aces[tmp_acl->num_aces] = *ace;
 213                                             desc_expand_generic(tmp_ctx,
 214                                                                 &tmp_acl->aces[tmp_acl->num_aces],
 215                                                                 owner,
 216                                                                 group);
 217                                             tmp_acl->aces[tmp_acl->num_aces].flags = SEC_ACE_FLAG_INHERITED_ACE;
 218                                             tmp_acl->num_aces++;
 219                                 }
 220                         }
 221                 }
 222         }
 223         if (tmp_acl->num_aces == 0) {
 224                 return NULL;
 225         }
 226         if (acl) {
 227                 tmp_acl->revision = acl->revision;
 228         }
 229         return tmp_acl;
 230 }
 231
 232 static struct security_acl *process_user_acl(TALLOC_CTX *mem_ctx,
 233                                              struct security_acl *acl,
 234                                              bool is_container,
 235                                              struct dom_sid *owner,
 236                                              struct dom_sid *group,
 237                                              struct GUID *object_list,
 238                                              bool is_protected)
 239 {
 240         uint32_t i;
 241         TALLOC_CTX *tmp_ctx = talloc_new(mem_ctx);
 242         struct security_acl *tmp_acl = talloc_zero(tmp_ctx, struct security_acl);
 243         struct security_acl *new_acl;
 244
 245         if (!acl)
 246                 return NULL;
 247
 248         if (!tmp_acl)
 249                 return NULL;
 250
 251         tmp_acl->revision = acl->revision;
 252         DEBUG(6,(__location__ ": acl revision %d\n", acl->revision));
 253
 254         for (i=0; i < acl->num_aces; i++){
 255                 struct security_ace *ace = &acl->aces[i];
 256                 /* Remove ID flags from user-provided ACEs
 257                  * if we break inheritance, ignore them otherwise */
 258                 if (ace->flags & SEC_ACE_FLAG_INHERITED_ACE) {
 259                         if (is_protected) {
 260                                 ace->flags &= ~SEC_ACE_FLAG_INHERITED_ACE;
 261                         } else {
 262                                 continue;
 263                         }
 264                 }
 265
 266                 if (ace->flags & SEC_ACE_FLAG_INHERIT_ONLY &&
 267                     !(ace->flags & SEC_ACE_FLAG_CONTAINER_INHERIT ||
 268                       ace->flags & SEC_ACE_FLAG_OBJECT_INHERIT))
 269                         continue;
 270
 271                 tmp_acl->aces = talloc_realloc(tmp_acl,
 272                                                tmp_acl->aces,
 273                                                struct security_ace,
 274                                                tmp_acl->num_aces+1);
 275                 tmp_acl->aces[tmp_acl->num_aces] = *ace;
 276                 tmp_acl->num_aces++;
 277                 if (ace->flags & SEC_ACE_FLAG_INHERIT_ONLY) {
 278                         continue;
 279                 }
 280                 /* if the ACE contains CO, CG, GA, GE, GR or GW, and is inheritable
 281                  * it has to be expanded to two aces, the original as IO,
 282                  * and another one where these are translated */
 283                 if (desc_ace_has_generic(tmp_ctx, ace)) {
 284                         if (!(ace->flags & SEC_ACE_FLAG_CONTAINER_INHERIT)) {
 285                                 desc_expand_generic(tmp_ctx,
 286                                                     &tmp_acl->aces[tmp_acl->num_aces-1],
 287                                                     owner,
 288                                                     group);
 289                         } else {
 290                                 /*The original ACE becomes read only */
 291                                 tmp_acl->aces[tmp_acl->num_aces-1].flags |= SEC_ACE_FLAG_INHERIT_ONLY;
 292                                 tmp_acl->aces = talloc_realloc(tmp_acl, tmp_acl->aces,
 293                                                                struct security_ace,
 294                                                                tmp_acl->num_aces+1);
 295                                 /* add a new ACE with expanded generic info */
 296                                 tmp_acl->aces[tmp_acl->num_aces] = *ace;
 297                                 desc_expand_generic(tmp_ctx,
 298                                                     &tmp_acl->aces[tmp_acl->num_aces],
 299                                                     owner,
 300                                                     group);
 301                                 tmp_acl->num_aces++;
 302                         }
 303                 }
 304         }
 305         new_acl = security_acl_dup(mem_ctx,tmp_acl);
 306
 307         if (new_acl)
 308                 new_acl->revision = acl->revision;
 309
 310         talloc_free(tmp_ctx);
 311         return new_acl;
 312 }
 313
 314 static void cr_descr_log_descriptor(struct security_descriptor *sd,
 315                                     const char *message,
 316                                     int level)
 317 {
 318         if (sd) {
 319                 DEBUG(level,("%s: %s\n", message,
 320                              ndr_print_struct_string(0,(ndr_print_fn_t)ndr_print_security_descriptor,
 321                                                      "", sd)));
 322         }
 323         else {
 324                 DEBUG(level,("%s: NULL\n", message));
 325         }
 326 }
 327
 328 #if 0
 329 static void cr_descr_log_acl(struct security_acl *acl,
 330                                     const char *message,
 331                                     int level)
 332 {
 333         if (acl) {
 334                 DEBUG(level,("%s: %s\n", message,
 335                              ndr_print_struct_string(0,(ndr_print_fn_t)ndr_print_security_acl,
 336                                                      "", acl)));
 337         }
 338         else {
 339                 DEBUG(level,("%s: NULL\n", message));
 340         }
 341 }
 342 #endif
 343
 344 static bool compute_acl(struct security_descriptor *parent_sd,
 345                         struct security_descriptor *creator_sd,
 346                         bool is_container,
 347                         uint32_t inherit_flags,
 348                         struct GUID *object_list,
 349                         uint32_t (*generic_map)(uint32_t access_mask),
 350                         struct security_token *token,
 351                         struct security_descriptor *new_sd) /* INOUT argument */
 352 {
 353         struct security_acl *user_dacl, *user_sacl, *inherited_dacl, *inherited_sacl;
 354         int level = 10;
 355
 356         if (!parent_sd || !(inherit_flags & SEC_DACL_AUTO_INHERIT)) {
 357                 inherited_dacl = NULL;
 358         } else if (creator_sd && (creator_sd->type & SEC_DESC_DACL_PROTECTED)) {
 359                 inherited_dacl = NULL;
 360         } else {
 361                 inherited_dacl = calculate_inherited_from_parent(new_sd,
 362                                                                  parent_sd->dacl,
 363                                                                  is_container,
 364                                                                  new_sd->owner_sid,
 365                                                                  new_sd->group_sid,
 366                                                                  object_list);
 367         }
 368
 369
 370         if (!parent_sd || !(inherit_flags & SEC_SACL_AUTO_INHERIT)) {
 371                 inherited_sacl = NULL;
 372         } else if (creator_sd && (creator_sd->type & SEC_DESC_SACL_PROTECTED)) {
 373                 inherited_sacl = NULL;
 374         } else {
 375                 inherited_sacl = calculate_inherited_from_parent(new_sd,
 376                                                                  parent_sd->sacl,
 377                                                                  is_container,
 378                                                                  new_sd->owner_sid,
 379                                                                  new_sd->group_sid,
 380                                                                  object_list);
 381         }
 382
 383         if (!creator_sd || (inherit_flags & SEC_DEFAULT_DESCRIPTOR)) {
 384                 user_dacl = NULL;
 385                 user_sacl = NULL;
 386         } else {
 387                 user_dacl = process_user_acl(new_sd,
 388                                              creator_sd->dacl,
 389                                              is_container,
 390                                              new_sd->owner_sid,
 391                                              new_sd->group_sid,
 392                                              object_list,
 393                                              creator_sd->type & SEC_DESC_DACL_PROTECTED);
 394                 user_sacl = process_user_acl(new_sd,
 395                                              creator_sd->sacl,
 396                                              is_container,
 397                                              new_sd->owner_sid,
 398                                              new_sd->group_sid,
 399                                              object_list,
 400                                              creator_sd->type & SEC_DESC_SACL_PROTECTED);
 401         }
 402         cr_descr_log_descriptor(parent_sd, __location__"parent_sd", level);
 403         cr_descr_log_descriptor(creator_sd,__location__ "creator_sd", level);
 404
 405         new_sd->dacl = security_acl_concatenate(new_sd, user_dacl, inherited_dacl);
 406         if (new_sd->dacl) {
 407                 new_sd->type |= SEC_DESC_DACL_PRESENT;
 408         }
 409         if (inherited_dacl) {
 410                 new_sd->type |= SEC_DESC_DACL_AUTO_INHERITED;
 411         }
 412
 413         new_sd->sacl = security_acl_concatenate(new_sd, user_sacl, inherited_sacl);
 414         if (new_sd->sacl) {
 415                 new_sd->type |= SEC_DESC_SACL_PRESENT;
 416         }
 417         if (inherited_sacl) {
 418                 new_sd->type |= SEC_DESC_SACL_AUTO_INHERITED;
 419         }
 420         /* This is a hack to handle the fact that
 421          * apprantly any AI flag provided by the user is preserved */
 422         if (creator_sd)
 423                 new_sd->type |= creator_sd->type;
 424         cr_descr_log_descriptor(new_sd, __location__"final sd", level);
 425         return true;
 426 }
 427
 428 struct security_descriptor *create_security_descriptor(TALLOC_CTX *mem_ctx,
 429                                                        struct security_descriptor *parent_sd,
 430                                                        struct security_descriptor *creator_sd,
 431                                                        bool is_container,
 432                                                        struct GUID *object_list,
 433                                                        uint32_t inherit_flags,
 434                                                        struct security_token *token,
 435                                                        struct dom_sid *default_owner, /* valid only for DS, NULL for the other RSs */
 436                                                        struct dom_sid *default_group, /* valid only for DS, NULL for the other RSs */
 437                                                        uint32_t (*generic_map)(uint32_t access_mask))
 438 {
 439         struct security_descriptor *new_sd;
 440         struct dom_sid *new_owner = NULL;
 441         struct dom_sid *new_group = NULL;
 442
 443         new_sd = security_descriptor_initialise(mem_ctx);
 444         if (!new_sd) {
 445                 return NULL;
 446         }
 447
 448         if (!creator_sd || !creator_sd->owner_sid) {
 449                 if ((inherit_flags & SEC_OWNER_FROM_PARENT) && parent_sd) {
 450                         new_owner = parent_sd->owner_sid;
 451                 } else if (!default_owner) {
 452                         new_owner = &token->sids[PRIMARY_USER_SID_INDEX];
 453                 } else {
 454                         new_owner = default_owner;
 455                         new_sd->type |= SEC_DESC_OWNER_DEFAULTED;
 456                 }
 457         } else {
 458                 new_owner = creator_sd->owner_sid;
 459         }
 460
 461         if (!creator_sd || !creator_sd->group_sid){
 462                 if ((inherit_flags & SEC_GROUP_FROM_PARENT) && parent_sd) {
 463                         new_group = parent_sd->group_sid;
 464                 } else if (!default_group && token->num_sids > PRIMARY_GROUP_SID_INDEX) {
 465                         new_group = &token->sids[PRIMARY_GROUP_SID_INDEX];
 466                 } else if (!default_group) {
 467                         /* This will happen only for anonymous, which has no other groups */
 468                         new_group = &token->sids[PRIMARY_USER_SID_INDEX];
 469                 } else {
 470                         new_group = default_group;
 471                         new_sd->type |= SEC_DESC_GROUP_DEFAULTED;
 472                 }
 473         } else {
 474                 new_group = creator_sd->group_sid;
 475         }
 476
 477         new_sd->owner_sid = talloc_memdup(new_sd, new_owner, sizeof(struct dom_sid));
 478         new_sd->group_sid = talloc_memdup(new_sd, new_group, sizeof(struct dom_sid));
 479         if (!new_sd->owner_sid || !new_sd->group_sid){
 480                 talloc_free(new_sd);
 481                 return NULL;
 482         }
 483
 484         if (!compute_acl(parent_sd, creator_sd,
 485                          is_container, inherit_flags, object_list,
 486                          generic_map,token,new_sd)){
 487                 talloc_free(new_sd);
 488                 return NULL;
 489         }
 490
 491         return new_sd;
 492 }