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                         struct GUID inherited_object = GUID_zero();
 169
 170                         tmp_acl->aces = talloc_realloc(tmp_acl, tmp_acl->aces,
 171                                                        struct security_ace,
 172                                                        tmp_acl->num_aces+1);
 173                         if (tmp_acl->aces == NULL) {
 174                                 talloc_free(tmp_ctx);
 175                                 return NULL;
 176                         }
 177
 178                         tmp_acl->aces[tmp_acl->num_aces] = *ace;
 179                         tmp_acl->aces[tmp_acl->num_aces].flags |= SEC_ACE_FLAG_INHERITED_ACE;
 180                         /* remove IO flag from the child's ace */
 181                         if (ace->flags & SEC_ACE_FLAG_INHERIT_ONLY &&
 182                             !desc_ace_has_generic(tmp_ctx, ace)) {
 183                                 tmp_acl->aces[tmp_acl->num_aces].flags &= ~SEC_ACE_FLAG_INHERIT_ONLY;
 184                         }
 185
 186                         if (is_container && (ace->flags & SEC_ACE_FLAG_OBJECT_INHERIT))
 187                             tmp_acl->aces[tmp_acl->num_aces].flags |= SEC_ACE_FLAG_INHERIT_ONLY;
 188
 189                         switch (ace->type) {
 190                         case SEC_ACE_TYPE_ACCESS_ALLOWED:
 191                         case SEC_ACE_TYPE_ACCESS_DENIED:
 192                         case SEC_ACE_TYPE_SYSTEM_AUDIT:
 193                         case SEC_ACE_TYPE_SYSTEM_ALARM:
 194                         case SEC_ACE_TYPE_ALLOWED_COMPOUND:
 195                                 break;
 196
 197                         case SEC_ACE_TYPE_ACCESS_ALLOWED_OBJECT:
 198                         case SEC_ACE_TYPE_ACCESS_DENIED_OBJECT:
 199                         case SEC_ACE_TYPE_SYSTEM_ALARM_OBJECT:
 200                         case SEC_ACE_TYPE_SYSTEM_AUDIT_OBJECT:
 201                                 if (ace->object.object.flags & SEC_ACE_INHERITED_OBJECT_TYPE_PRESENT) {
 202                                         inherited_object = ace->object.object.inherited_type.inherited_type;
 203                                 }
 204
 205                                 if (!object_in_list(object_list, &inherited_object)) {
 206                                         tmp_acl->aces[tmp_acl->num_aces].flags |= SEC_ACE_FLAG_INHERIT_ONLY;
 207                                 }
 208
 209                                 break;
 210                         }
 211
 212                         tmp_acl->num_aces++;
 213                         if (is_container) {
 214                                 if (!(ace->flags & SEC_ACE_FLAG_NO_PROPAGATE_INHERIT) &&
 215                                     (desc_ace_has_generic(tmp_ctx, ace))) {
 216                                             tmp_acl->aces = talloc_realloc(tmp_acl,
 217                                                                            tmp_acl->aces,
 218                                                                            struct security_ace,
 219                                                                            tmp_acl->num_aces+1);
 220                                             if (tmp_acl->aces == NULL) {
 221                                                     talloc_free(tmp_ctx);
 222                                                     return NULL;
 223                                             }
 224                                             tmp_acl->aces[tmp_acl->num_aces] = *ace;
 225                                             desc_expand_generic(tmp_ctx,
 226                                                                 &tmp_acl->aces[tmp_acl->num_aces],
 227                                                                 owner,
 228                                                                 group);
 229                                             tmp_acl->aces[tmp_acl->num_aces].flags = SEC_ACE_FLAG_INHERITED_ACE;
 230                                             tmp_acl->num_aces++;
 231                                 }
 232                         }
 233                 }
 234         }
 235         if (tmp_acl->num_aces == 0) {
 236                 return NULL;
 237         }
 238         if (acl) {
 239                 tmp_acl->revision = acl->revision;
 240         }
 241         return tmp_acl;
 242 }
 243
 244 static struct security_acl *process_user_acl(TALLOC_CTX *mem_ctx,
 245                                              struct security_acl *acl,
 246                                              bool is_container,
 247                                              struct dom_sid *owner,
 248                                              struct dom_sid *group,
 249                                              struct GUID *object_list,
 250                                              bool is_protected)
 251 {
 252         uint32_t i;
 253         TALLOC_CTX *tmp_ctx = talloc_new(mem_ctx);
 254         struct security_acl *tmp_acl = talloc_zero(tmp_ctx, struct security_acl);
 255         struct security_acl *new_acl;
 256
 257         if (!acl)
 258                 return NULL;
 259
 260         if (!tmp_acl)
 261                 return NULL;
 262
 263         tmp_acl->revision = acl->revision;
 264         DEBUG(6,(__location__ ": acl revision %d\n", acl->revision));
 265
 266         for (i=0; i < acl->num_aces; i++){
 267                 struct security_ace *ace = &acl->aces[i];
 268                 /* Remove ID flags from user-provided ACEs
 269                  * if we break inheritance, ignore them otherwise */
 270                 if (ace->flags & SEC_ACE_FLAG_INHERITED_ACE) {
 271                         if (is_protected) {
 272                                 ace->flags &= ~SEC_ACE_FLAG_INHERITED_ACE;
 273                         } else {
 274                                 continue;
 275                         }
 276                 }
 277
 278                 if (ace->flags & SEC_ACE_FLAG_INHERIT_ONLY &&
 279                     !(ace->flags & SEC_ACE_FLAG_CONTAINER_INHERIT ||
 280                       ace->flags & SEC_ACE_FLAG_OBJECT_INHERIT))
 281                         continue;
 282
 283                 tmp_acl->aces = talloc_realloc(tmp_acl,
 284                                                tmp_acl->aces,
 285                                                struct security_ace,
 286                                                tmp_acl->num_aces+1);
 287                 tmp_acl->aces[tmp_acl->num_aces] = *ace;
 288                 tmp_acl->num_aces++;
 289                 if (ace->flags & SEC_ACE_FLAG_INHERIT_ONLY) {
 290                         continue;
 291                 }
 292                 /* if the ACE contains CO, CG, GA, GE, GR or GW, and is inheritable
 293                  * it has to be expanded to two aces, the original as IO,
 294                  * and another one where these are translated */
 295                 if (desc_ace_has_generic(tmp_ctx, ace)) {
 296                         if (!(ace->flags & SEC_ACE_FLAG_CONTAINER_INHERIT)) {
 297                                 desc_expand_generic(tmp_ctx,
 298                                                     &tmp_acl->aces[tmp_acl->num_aces-1],
 299                                                     owner,
 300                                                     group);
 301                         } else {
 302                                 /*The original ACE becomes read only */
 303                                 tmp_acl->aces[tmp_acl->num_aces-1].flags |= SEC_ACE_FLAG_INHERIT_ONLY;
 304                                 tmp_acl->aces = talloc_realloc(tmp_acl, tmp_acl->aces,
 305                                                                struct security_ace,
 306                                                                tmp_acl->num_aces+1);
 307                                 /* add a new ACE with expanded generic info */
 308                                 tmp_acl->aces[tmp_acl->num_aces] = *ace;
 309                                 desc_expand_generic(tmp_ctx,
 310                                                     &tmp_acl->aces[tmp_acl->num_aces],
 311                                                     owner,
 312                                                     group);
 313                                 tmp_acl->num_aces++;
 314                         }
 315                 }
 316         }
 317         new_acl = security_acl_dup(mem_ctx,tmp_acl);
 318
 319         if (new_acl)
 320                 new_acl->revision = acl->revision;
 321
 322         talloc_free(tmp_ctx);
 323         return new_acl;
 324 }
 325
 326 static void cr_descr_log_descriptor(struct security_descriptor *sd,
 327                                     const char *message,
 328                                     int level)
 329 {
 330         if (sd) {
 331                 DEBUG(level,("%s: %s\n", message,
 332                              ndr_print_struct_string(0,(ndr_print_fn_t)ndr_print_security_descriptor,
 333                                                      "", sd)));
 334         }
 335         else {
 336                 DEBUG(level,("%s: NULL\n", message));
 337         }
 338 }
 339
 340 #if 0
 341 static void cr_descr_log_acl(struct security_acl *acl,
 342                                     const char *message,
 343                                     int level)
 344 {
 345         if (acl) {
 346                 DEBUG(level,("%s: %s\n", message,
 347                              ndr_print_struct_string(0,(ndr_print_fn_t)ndr_print_security_acl,
 348                                                      "", acl)));
 349         }
 350         else {
 351                 DEBUG(level,("%s: NULL\n", message));
 352         }
 353 }
 354 #endif
 355
 356 static bool compute_acl(struct security_descriptor *parent_sd,
 357                         struct security_descriptor *creator_sd,
 358                         bool is_container,
 359                         uint32_t inherit_flags,
 360                         struct GUID *object_list,
 361                         uint32_t (*generic_map)(uint32_t access_mask),
 362                         struct security_token *token,
 363                         struct security_descriptor *new_sd) /* INOUT argument */
 364 {
 365         struct security_acl *user_dacl, *user_sacl, *inherited_dacl, *inherited_sacl;
 366         int level = 10;
 367
 368         if (!parent_sd || !(inherit_flags & SEC_DACL_AUTO_INHERIT)) {
 369                 inherited_dacl = NULL;
 370         } else if (creator_sd && (creator_sd->type & SEC_DESC_DACL_PROTECTED)) {
 371                 inherited_dacl = NULL;
 372         } else {
 373                 inherited_dacl = calculate_inherited_from_parent(new_sd,
 374                                                                  parent_sd->dacl,
 375                                                                  is_container,
 376                                                                  new_sd->owner_sid,
 377                                                                  new_sd->group_sid,
 378                                                                  object_list);
 379         }
 380
 381
 382         if (!parent_sd || !(inherit_flags & SEC_SACL_AUTO_INHERIT)) {
 383                 inherited_sacl = NULL;
 384         } else if (creator_sd && (creator_sd->type & SEC_DESC_SACL_PROTECTED)) {
 385                 inherited_sacl = NULL;
 386         } else {
 387                 inherited_sacl = calculate_inherited_from_parent(new_sd,
 388                                                                  parent_sd->sacl,
 389                                                                  is_container,
 390                                                                  new_sd->owner_sid,
 391                                                                  new_sd->group_sid,
 392                                                                  object_list);
 393         }
 394
 395         if (!creator_sd || (inherit_flags & SEC_DEFAULT_DESCRIPTOR)) {
 396                 user_dacl = NULL;
 397                 user_sacl = NULL;
 398         } else {
 399                 user_dacl = process_user_acl(new_sd,
 400                                              creator_sd->dacl,
 401                                              is_container,
 402                                              new_sd->owner_sid,
 403                                              new_sd->group_sid,
 404                                              object_list,
 405                                              creator_sd->type & SEC_DESC_DACL_PROTECTED);
 406                 user_sacl = process_user_acl(new_sd,
 407                                              creator_sd->sacl,
 408                                              is_container,
 409                                              new_sd->owner_sid,
 410                                              new_sd->group_sid,
 411                                              object_list,
 412                                              creator_sd->type & SEC_DESC_SACL_PROTECTED);
 413         }
 414         cr_descr_log_descriptor(parent_sd, __location__"parent_sd", level);
 415         cr_descr_log_descriptor(creator_sd,__location__ "creator_sd", level);
 416
 417         new_sd->dacl = security_acl_concatenate(new_sd, user_dacl, inherited_dacl);
 418         if (new_sd->dacl) {
 419                 new_sd->type |= SEC_DESC_DACL_PRESENT;
 420         }
 421         if (inherited_dacl) {
 422                 new_sd->type |= SEC_DESC_DACL_AUTO_INHERITED;
 423         }
 424
 425         new_sd->sacl = security_acl_concatenate(new_sd, user_sacl, inherited_sacl);
 426         if (new_sd->sacl) {
 427                 new_sd->type |= SEC_DESC_SACL_PRESENT;
 428         }
 429         if (inherited_sacl) {
 430                 new_sd->type |= SEC_DESC_SACL_AUTO_INHERITED;
 431         }
 432         /* This is a hack to handle the fact that
 433          * apprantly any AI flag provided by the user is preserved */
 434         if (creator_sd)
 435                 new_sd->type |= creator_sd->type;
 436         cr_descr_log_descriptor(new_sd, __location__"final sd", level);
 437         return true;
 438 }
 439
 440 struct security_descriptor *create_security_descriptor(TALLOC_CTX *mem_ctx,
 441                                                        struct security_descriptor *parent_sd,
 442                                                        struct security_descriptor *creator_sd,
 443                                                        bool is_container,
 444                                                        struct GUID *object_list,
 445                                                        uint32_t inherit_flags,
 446                                                        struct security_token *token,
 447                                                        struct dom_sid *default_owner, /* valid only for DS, NULL for the other RSs */
 448                                                        struct dom_sid *default_group, /* valid only for DS, NULL for the other RSs */
 449                                                        uint32_t (*generic_map)(uint32_t access_mask))
 450 {
 451         struct security_descriptor *new_sd;
 452         struct dom_sid *new_owner = NULL;
 453         struct dom_sid *new_group = NULL;
 454
 455         new_sd = security_descriptor_initialise(mem_ctx);
 456         if (!new_sd) {
 457                 return NULL;
 458         }
 459
 460         if (!creator_sd || !creator_sd->owner_sid) {
 461                 if ((inherit_flags & SEC_OWNER_FROM_PARENT) && parent_sd) {
 462                         new_owner = parent_sd->owner_sid;
 463                 } else if (!default_owner) {
 464                         new_owner = &token->sids[PRIMARY_USER_SID_INDEX];
 465                 } else {
 466                         new_owner = default_owner;
 467                         new_sd->type |= SEC_DESC_OWNER_DEFAULTED;
 468                 }
 469         } else {
 470                 new_owner = creator_sd->owner_sid;
 471         }
 472
 473         if (!creator_sd || !creator_sd->group_sid){
 474                 if ((inherit_flags & SEC_GROUP_FROM_PARENT) && parent_sd) {
 475                         new_group = parent_sd->group_sid;
 476                 } else if (!default_group && token->num_sids > PRIMARY_GROUP_SID_INDEX) {
 477                         new_group = &token->sids[PRIMARY_GROUP_SID_INDEX];
 478                 } else if (!default_group) {
 479                         /* This will happen only for anonymous, which has no other groups */
 480                         new_group = &token->sids[PRIMARY_USER_SID_INDEX];
 481                 } else {
 482                         new_group = default_group;
 483                         new_sd->type |= SEC_DESC_GROUP_DEFAULTED;
 484                 }
 485         } else {
 486                 new_group = creator_sd->group_sid;
 487         }
 488
 489         new_sd->owner_sid = talloc_memdup(new_sd, new_owner, sizeof(struct dom_sid));
 490         new_sd->group_sid = talloc_memdup(new_sd, new_group, sizeof(struct dom_sid));
 491         if (!new_sd->owner_sid || !new_sd->group_sid){
 492                 talloc_free(new_sd);
 493                 return NULL;
 494         }
 495
 496         if (!compute_acl(parent_sd, creator_sd,
 497                          is_container, inherit_flags, object_list,
 498                          generic_map,token,new_sd)){
 499                 talloc_free(new_sd);
 500                 return NULL;
 501         }
 502
 503         return new_sd;
 504 }