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