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(struct security_ace *new_ace,
 129                                 struct dom_sid *owner,
 130                                 struct dom_sid *group)
 131 {
 132         new_ace->access_mask = map_generic_rights_ds(new_ace->access_mask);
 133         if (dom_sid_equal(&new_ace->trustee, &global_sid_Creator_Owner)) {
 134                 new_ace->trustee = *owner;
 135         }
 136         if (dom_sid_equal(&new_ace->trustee, &global_sid_Creator_Group)) {
 137                 new_ace->trustee = *group;
 138         }
 139         new_ace->flags = 0x0;
 140 }
 141
 142 static struct security_acl *calculate_inherited_from_parent(TALLOC_CTX *mem_ctx,
 143                                                             struct security_acl *acl,
 144                                                             bool is_container,
 145                                                             struct dom_sid *owner,
 146                                                             struct dom_sid *group,
 147                                                             struct GUID *object_list)
 148 {
 149         uint32_t i;
 150         TALLOC_CTX *tmp_ctx = talloc_new(mem_ctx);
 151         struct security_acl *tmp_acl = talloc_zero(mem_ctx, struct security_acl);
 152         if (!tmp_acl) {
 153                 return NULL;
 154         }
 155
 156         if (!acl) {
 157                 return NULL;
 158         }
 159
 160         for (i=0; i < acl->num_aces; i++) {
 161                 struct security_ace *ace = &acl->aces[i];
 162                 if ((ace->flags & SEC_ACE_FLAG_CONTAINER_INHERIT) ||
 163                     (ace->flags & SEC_ACE_FLAG_OBJECT_INHERIT)) {
 164                         struct GUID inherited_object = GUID_zero();
 165
 166                         tmp_acl->aces = talloc_realloc(tmp_acl, tmp_acl->aces,
 167                                                        struct security_ace,
 168                                                        tmp_acl->num_aces+1);
 169                         if (tmp_acl->aces == NULL) {
 170                                 talloc_free(tmp_ctx);
 171                                 return NULL;
 172                         }
 173
 174                         tmp_acl->aces[tmp_acl->num_aces] = *ace;
 175                         tmp_acl->aces[tmp_acl->num_aces].flags |= SEC_ACE_FLAG_INHERITED_ACE;
 176                         /* remove IO flag from the child's ace */
 177                         if (ace->flags & SEC_ACE_FLAG_INHERIT_ONLY &&
 178                             !desc_ace_has_generic(tmp_ctx, ace)) {
 179                                 tmp_acl->aces[tmp_acl->num_aces].flags &= ~SEC_ACE_FLAG_INHERIT_ONLY;
 180                         }
 181
 182                         if (is_container && (ace->flags & SEC_ACE_FLAG_OBJECT_INHERIT))
 183                             tmp_acl->aces[tmp_acl->num_aces].flags |= SEC_ACE_FLAG_INHERIT_ONLY;
 184
 185                         switch (ace->type) {
 186                         case SEC_ACE_TYPE_ACCESS_ALLOWED:
 187                         case SEC_ACE_TYPE_ACCESS_DENIED:
 188                         case SEC_ACE_TYPE_SYSTEM_AUDIT:
 189                         case SEC_ACE_TYPE_SYSTEM_ALARM:
 190                         case SEC_ACE_TYPE_ALLOWED_COMPOUND:
 191                                 break;
 192
 193                         case SEC_ACE_TYPE_ACCESS_ALLOWED_OBJECT:
 194                         case SEC_ACE_TYPE_ACCESS_DENIED_OBJECT:
 195                         case SEC_ACE_TYPE_SYSTEM_ALARM_OBJECT:
 196                         case SEC_ACE_TYPE_SYSTEM_AUDIT_OBJECT:
 197                                 if (ace->object.object.flags & SEC_ACE_INHERITED_OBJECT_TYPE_PRESENT) {
 198                                         inherited_object = ace->object.object.inherited_type.inherited_type;
 199                                 }
 200
 201                                 if (!object_in_list(object_list, &inherited_object)) {
 202                                         tmp_acl->aces[tmp_acl->num_aces].flags |= SEC_ACE_FLAG_INHERIT_ONLY;
 203                                 }
 204
 205                                 break;
 206                         }
 207
 208                         tmp_acl->num_aces++;
 209                         if (is_container) {
 210                                 if (!(ace->flags & SEC_ACE_FLAG_NO_PROPAGATE_INHERIT) &&
 211                                     (desc_ace_has_generic(tmp_ctx, ace))) {
 212                                             tmp_acl->aces = talloc_realloc(tmp_acl,
 213                                                                            tmp_acl->aces,
 214                                                                            struct security_ace,
 215                                                                            tmp_acl->num_aces+1);
 216                                             if (tmp_acl->aces == NULL) {
 217                                                     talloc_free(tmp_ctx);
 218                                                     return NULL;
 219                                             }
 220                                             tmp_acl->aces[tmp_acl->num_aces] = *ace;
 221                                             desc_expand_generic(&tmp_acl->aces[tmp_acl->num_aces],
 222                                                                 owner,
 223                                                                 group);
 224                                             tmp_acl->aces[tmp_acl->num_aces].flags = SEC_ACE_FLAG_INHERITED_ACE;
 225                                             tmp_acl->num_aces++;
 226                                 }
 227                         }
 228                 }
 229         }
 230         if (tmp_acl->num_aces == 0) {
 231                 return NULL;
 232         }
 233         if (acl) {
 234                 tmp_acl->revision = acl->revision;
 235         }
 236         return tmp_acl;
 237 }
 238
 239 static struct security_acl *process_user_acl(TALLOC_CTX *mem_ctx,
 240                                              struct security_acl *acl,
 241                                              bool is_container,
 242                                              struct dom_sid *owner,
 243                                              struct dom_sid *group,
 244                                              struct GUID *object_list,
 245                                              bool is_protected)
 246 {
 247         uint32_t i;
 248         TALLOC_CTX *tmp_ctx = talloc_new(mem_ctx);
 249         struct security_acl *tmp_acl = talloc_zero(tmp_ctx, struct security_acl);
 250         struct security_acl *new_acl;
 251
 252         if (!acl)
 253                 return NULL;
 254
 255         if (!tmp_acl)
 256                 return NULL;
 257
 258         tmp_acl->revision = acl->revision;
 259         DEBUG(6,(__location__ ": acl revision %d\n", acl->revision));
 260
 261         for (i=0; i < acl->num_aces; i++){
 262                 struct security_ace *ace = &acl->aces[i];
 263                 /* Remove ID flags from user-provided ACEs
 264                  * if we break inheritance, ignore them otherwise */
 265                 if (ace->flags & SEC_ACE_FLAG_INHERITED_ACE) {
 266                         if (is_protected) {
 267                                 ace->flags &= ~SEC_ACE_FLAG_INHERITED_ACE;
 268                         } else {
 269                                 continue;
 270                         }
 271                 }
 272
 273                 if (ace->flags & SEC_ACE_FLAG_INHERIT_ONLY &&
 274                     !(ace->flags & SEC_ACE_FLAG_CONTAINER_INHERIT ||
 275                       ace->flags & SEC_ACE_FLAG_OBJECT_INHERIT))
 276                         continue;
 277
 278                 tmp_acl->aces = talloc_realloc(tmp_acl,
 279                                                tmp_acl->aces,
 280                                                struct security_ace,
 281                                                tmp_acl->num_aces+1);
 282                 tmp_acl->aces[tmp_acl->num_aces] = *ace;
 283                 tmp_acl->num_aces++;
 284                 if (ace->flags & SEC_ACE_FLAG_INHERIT_ONLY) {
 285                         continue;
 286                 }
 287                 /* if the ACE contains CO, CG, GA, GE, GR or GW, and is inheritable
 288                  * it has to be expanded to two aces, the original as IO,
 289                  * and another one where these are translated */
 290                 if (desc_ace_has_generic(tmp_ctx, ace)) {
 291                         if (!(ace->flags & SEC_ACE_FLAG_CONTAINER_INHERIT)) {
 292                                 desc_expand_generic(&tmp_acl->aces[tmp_acl->num_aces-1],
 293                                                     owner,
 294                                                     group);
 295                         } else {
 296                                 /*The original ACE becomes read only */
 297                                 tmp_acl->aces[tmp_acl->num_aces-1].flags |= SEC_ACE_FLAG_INHERIT_ONLY;
 298                                 tmp_acl->aces = talloc_realloc(tmp_acl, tmp_acl->aces,
 299                                                                struct security_ace,
 300                                                                tmp_acl->num_aces+1);
 301                                 /* add a new ACE with expanded generic info */
 302                                 tmp_acl->aces[tmp_acl->num_aces] = *ace;
 303                                 desc_expand_generic(&tmp_acl->aces[tmp_acl->num_aces],
 304                                                     owner,
 305                                                     group);
 306                                 tmp_acl->num_aces++;
 307                         }
 308                 }
 309         }
 310         new_acl = security_acl_dup(mem_ctx,tmp_acl);
 311
 312         if (new_acl)
 313                 new_acl->revision = acl->revision;
 314
 315         talloc_free(tmp_ctx);
 316         return new_acl;
 317 }
 318
 319 static void cr_descr_log_descriptor(struct security_descriptor *sd,
 320                                     const char *message,
 321                                     int level)
 322 {
 323         if (sd) {
 324                 DEBUG(level,("%s: %s\n", message,
 325                              ndr_print_struct_string(0,(ndr_print_fn_t)ndr_print_security_descriptor,
 326                                                      "", sd)));
 327         }
 328         else {
 329                 DEBUG(level,("%s: NULL\n", message));
 330         }
 331 }
 332
 333 #if 0
 334 static void cr_descr_log_acl(struct security_acl *acl,
 335                                     const char *message,
 336                                     int level)
 337 {
 338         if (acl) {
 339                 DEBUG(level,("%s: %s\n", message,
 340                              ndr_print_struct_string(0,(ndr_print_fn_t)ndr_print_security_acl,
 341                                                      "", acl)));
 342         }
 343         else {
 344                 DEBUG(level,("%s: NULL\n", message));
 345         }
 346 }
 347 #endif
 348
 349 static bool compute_acl(struct security_descriptor *parent_sd,
 350                         struct security_descriptor *creator_sd,
 351                         bool is_container,
 352                         uint32_t inherit_flags,
 353                         struct GUID *object_list,
 354                         uint32_t (*generic_map)(uint32_t access_mask),
 355                         struct security_token *token,
 356                         struct security_descriptor *new_sd) /* INOUT argument */
 357 {
 358         struct security_acl *user_dacl, *user_sacl, *inherited_dacl, *inherited_sacl;
 359         int level = 10;
 360
 361         if (!parent_sd || !(inherit_flags & SEC_DACL_AUTO_INHERIT)) {
 362                 inherited_dacl = NULL;
 363         } else if (creator_sd && (creator_sd->type & SEC_DESC_DACL_PROTECTED)) {
 364                 inherited_dacl = NULL;
 365         } else {
 366                 inherited_dacl = calculate_inherited_from_parent(new_sd,
 367                                                                  parent_sd->dacl,
 368                                                                  is_container,
 369                                                                  new_sd->owner_sid,
 370                                                                  new_sd->group_sid,
 371                                                                  object_list);
 372         }
 373
 374
 375         if (!parent_sd || !(inherit_flags & SEC_SACL_AUTO_INHERIT)) {
 376                 inherited_sacl = NULL;
 377         } else if (creator_sd && (creator_sd->type & SEC_DESC_SACL_PROTECTED)) {
 378                 inherited_sacl = NULL;
 379         } else {
 380                 inherited_sacl = calculate_inherited_from_parent(new_sd,
 381                                                                  parent_sd->sacl,
 382                                                                  is_container,
 383                                                                  new_sd->owner_sid,
 384                                                                  new_sd->group_sid,
 385                                                                  object_list);
 386         }
 387
 388         if (!creator_sd || (inherit_flags & SEC_DEFAULT_DESCRIPTOR)) {
 389                 user_dacl = NULL;
 390                 user_sacl = NULL;
 391         } else {
 392                 user_dacl = process_user_acl(new_sd,
 393                                              creator_sd->dacl,
 394                                              is_container,
 395                                              new_sd->owner_sid,
 396                                              new_sd->group_sid,
 397                                              object_list,
 398                                              creator_sd->type & SEC_DESC_DACL_PROTECTED);
 399                 user_sacl = process_user_acl(new_sd,
 400                                              creator_sd->sacl,
 401                                              is_container,
 402                                              new_sd->owner_sid,
 403                                              new_sd->group_sid,
 404                                              object_list,
 405                                              creator_sd->type & SEC_DESC_SACL_PROTECTED);
 406         }
 407         cr_descr_log_descriptor(parent_sd, __location__"parent_sd", level);
 408         cr_descr_log_descriptor(creator_sd,__location__ "creator_sd", level);
 409
 410         new_sd->dacl = security_acl_concatenate(new_sd, user_dacl, inherited_dacl);
 411         if (new_sd->dacl) {
 412                 new_sd->type |= SEC_DESC_DACL_PRESENT;
 413         }
 414         if (inherited_dacl) {
 415                 new_sd->type |= SEC_DESC_DACL_AUTO_INHERITED;
 416         }
 417
 418         new_sd->sacl = security_acl_concatenate(new_sd, user_sacl, inherited_sacl);
 419         if (new_sd->sacl) {
 420                 new_sd->type |= SEC_DESC_SACL_PRESENT;
 421         }
 422         if (inherited_sacl) {
 423                 new_sd->type |= SEC_DESC_SACL_AUTO_INHERITED;
 424         }
 425         /* This is a hack to handle the fact that
 426          * apprantly any AI flag provided by the user is preserved */
 427         if (creator_sd)
 428                 new_sd->type |= creator_sd->type;
 429         cr_descr_log_descriptor(new_sd, __location__"final sd", level);
 430         return true;
 431 }
 432
 433 struct security_descriptor *create_security_descriptor(TALLOC_CTX *mem_ctx,
 434                                                        struct security_descriptor *parent_sd,
 435                                                        struct security_descriptor *creator_sd,
 436                                                        bool is_container,
 437                                                        struct GUID *object_list,
 438                                                        uint32_t inherit_flags,
 439                                                        struct security_token *token,
 440                                                        struct dom_sid *default_owner, /* valid only for DS, NULL for the other RSs */
 441                                                        struct dom_sid *default_group, /* valid only for DS, NULL for the other RSs */
 442                                                        uint32_t (*generic_map)(uint32_t access_mask))
 443 {
 444         struct security_descriptor *new_sd;
 445         struct dom_sid *new_owner = NULL;
 446         struct dom_sid *new_group = NULL;
 447
 448         new_sd = security_descriptor_initialise(mem_ctx);
 449         if (!new_sd) {
 450                 return NULL;
 451         }
 452
 453         if (!creator_sd || !creator_sd->owner_sid) {
 454                 if ((inherit_flags & SEC_OWNER_FROM_PARENT) && parent_sd) {
 455                         new_owner = parent_sd->owner_sid;
 456                 } else if (!default_owner) {
 457                         new_owner = &token->sids[PRIMARY_USER_SID_INDEX];
 458                 } else {
 459                         new_owner = default_owner;
 460                         new_sd->type |= SEC_DESC_OWNER_DEFAULTED;
 461                 }
 462         } else {
 463                 new_owner = creator_sd->owner_sid;
 464         }
 465
 466         if (!creator_sd || !creator_sd->group_sid){
 467                 if ((inherit_flags & SEC_GROUP_FROM_PARENT) && parent_sd) {
 468                         new_group = parent_sd->group_sid;
 469                 } else if (!default_group && token->num_sids > PRIMARY_GROUP_SID_INDEX) {
 470                         new_group = &token->sids[PRIMARY_GROUP_SID_INDEX];
 471                 } else if (!default_group) {
 472                         /* This will happen only for anonymous, which has no other groups */
 473                         new_group = &token->sids[PRIMARY_USER_SID_INDEX];
 474                 } else {
 475                         new_group = default_group;
 476                         new_sd->type |= SEC_DESC_GROUP_DEFAULTED;
 477                 }
 478         } else {
 479                 new_group = creator_sd->group_sid;
 480         }
 481
 482         new_sd->owner_sid = talloc_memdup(new_sd, new_owner, sizeof(struct dom_sid));
 483         new_sd->group_sid = talloc_memdup(new_sd, new_group, sizeof(struct dom_sid));
 484         if (!new_sd->owner_sid || !new_sd->group_sid){
 485                 talloc_free(new_sd);
 486                 return NULL;
 487         }
 488
 489         if (!compute_acl(parent_sd, creator_sd,
 490                          is_container, inherit_flags, object_list,
 491                          generic_map,token,new_sd)){
 492                 talloc_free(new_sd);
 493                 return NULL;
 494         }
 495
 496         return new_sd;
 497 }