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         return true;
  84 }
  85
  86 /* returns true if the ACE gontains generic information
  87  * that needs to be processed additionally */
  88
  89 static bool desc_ace_has_generic(TALLOC_CTX *mem_ctx,
  90                              struct security_ace *ace)
  91 {
  92         struct dom_sid *co, *cg;
  93         co = dom_sid_parse_talloc(mem_ctx,  SID_CREATOR_OWNER);
  94         cg = dom_sid_parse_talloc(mem_ctx,  SID_CREATOR_GROUP);
  95         if (ace->access_mask & SEC_GENERIC_ALL || ace->access_mask & SEC_GENERIC_READ ||
  96             ace->access_mask & SEC_GENERIC_WRITE || ace->access_mask & SEC_GENERIC_EXECUTE) {
  97                 return true;
  98         }
  99         if (dom_sid_equal(&ace->trustee, co) || dom_sid_equal(&ace->trustee, cg)) {
 100                 return true;
 101         }
 102         return false;
 103 }
 104
 105 /* creates an ace in which the generic information is expanded */
 106
 107 static void desc_expand_generic(TALLOC_CTX *mem_ctx,
 108                                 struct security_ace *new_ace,
 109                                 struct dom_sid *owner,
 110                                 struct dom_sid *group)
 111 {
 112         struct dom_sid *co, *cg;
 113         co = dom_sid_parse_talloc(mem_ctx,  SID_CREATOR_OWNER);
 114         cg = dom_sid_parse_talloc(mem_ctx,  SID_CREATOR_GROUP);
 115         new_ace->access_mask = map_generic_rights_ds(new_ace->access_mask);
 116         if (dom_sid_equal(&new_ace->trustee, co)) {
 117                 new_ace->trustee = *owner;
 118         }
 119         if (dom_sid_equal(&new_ace->trustee, cg)) {
 120                 new_ace->trustee = *group;
 121         }
 122         new_ace->flags = 0x0;
 123 }
 124
 125 static struct security_acl *calculate_inherited_from_parent(TALLOC_CTX *mem_ctx,
 126                                                             struct security_acl *acl,
 127                                                             bool is_container,
 128                                                             struct dom_sid *owner,
 129                                                             struct dom_sid *group,
 130                                                             struct GUID *object_list)
 131 {
 132         uint32_t i;
 133         TALLOC_CTX *tmp_ctx = talloc_new(mem_ctx);
 134         struct security_acl *tmp_acl = talloc_zero(mem_ctx, struct security_acl);
 135         struct dom_sid *co, *cg;
 136         if (!tmp_acl) {
 137                 return NULL;
 138         }
 139
 140         if (!acl) {
 141                 return NULL;
 142         }
 143         co = dom_sid_parse_talloc(tmp_ctx,  SID_CREATOR_OWNER);
 144         cg = dom_sid_parse_talloc(tmp_ctx,  SID_CREATOR_GROUP);
 145
 146         for (i=0; i < acl->num_aces; i++) {
 147                 struct security_ace *ace = &acl->aces[i];
 148                 if ((ace->flags & SEC_ACE_FLAG_CONTAINER_INHERIT) ||
 149                     (ace->flags & SEC_ACE_FLAG_OBJECT_INHERIT)) {
 150                         tmp_acl->aces = talloc_realloc(tmp_acl, tmp_acl->aces,
 151                                                        struct security_ace,
 152                                                        tmp_acl->num_aces+1);
 153                         if (tmp_acl->aces == NULL) {
 154                                 talloc_free(tmp_ctx);
 155                                 return NULL;
 156                         }
 157
 158                         tmp_acl->aces[tmp_acl->num_aces] = *ace;
 159                         tmp_acl->aces[tmp_acl->num_aces].flags |= SEC_ACE_FLAG_INHERITED_ACE;
 160                         /* remove IO flag from the child's ace */
 161                         if (ace->flags & SEC_ACE_FLAG_INHERIT_ONLY &&
 162                             !desc_ace_has_generic(tmp_ctx, ace)) {
 163                                 tmp_acl->aces[tmp_acl->num_aces].flags &= ~SEC_ACE_FLAG_INHERIT_ONLY;
 164                         }
 165
 166                         if (is_container && (ace->flags & SEC_ACE_FLAG_OBJECT_INHERIT))
 167                             tmp_acl->aces[tmp_acl->num_aces].flags |= SEC_ACE_FLAG_INHERIT_ONLY;
 168
 169                         if (ace->type == SEC_ACE_TYPE_ACCESS_ALLOWED_OBJECT ||
 170                             ace->type == SEC_ACE_TYPE_ACCESS_DENIED_OBJECT) {
 171                                 if (!object_in_list(object_list, &ace->object.object.type.type)) {
 172                                         tmp_acl->aces[tmp_acl->num_aces].flags |= SEC_ACE_FLAG_INHERIT_ONLY;
 173                                 }
 174
 175                         }
 176                         tmp_acl->num_aces++;
 177                         if (is_container) {
 178                                 if (!(ace->flags & SEC_ACE_FLAG_NO_PROPAGATE_INHERIT) &&
 179                                     (desc_ace_has_generic(tmp_ctx, ace))) {
 180                                             tmp_acl->aces = talloc_realloc(tmp_acl,
 181                                                                            tmp_acl->aces,
 182                                                                            struct security_ace,
 183                                                                            tmp_acl->num_aces+1);
 184                                             if (tmp_acl->aces == NULL) {
 185                                                     talloc_free(tmp_ctx);
 186                                                     return NULL;
 187                                             }
 188                                             tmp_acl->aces[tmp_acl->num_aces] = *ace;
 189                                             desc_expand_generic(tmp_ctx,
 190                                                                 &tmp_acl->aces[tmp_acl->num_aces],
 191                                                                 owner,
 192                                                                 group);
 193                                             tmp_acl->aces[tmp_acl->num_aces].flags = SEC_ACE_FLAG_INHERITED_ACE;
 194                                             tmp_acl->num_aces++;
 195                                 }
 196                         }
 197                 }
 198         }
 199         if (tmp_acl->num_aces == 0) {
 200                 return NULL;
 201         }
 202         if (acl) {
 203                 tmp_acl->revision = acl->revision;
 204         }
 205         return tmp_acl;
 206 }
 207
 208 static struct security_acl *process_user_acl(TALLOC_CTX *mem_ctx,
 209                                              struct security_acl *acl,
 210                                              bool is_container,
 211                                              struct dom_sid *owner,
 212                                              struct dom_sid *group,
 213                                              struct GUID *object_list,
 214                                              bool is_protected)
 215 {
 216         uint32_t i;
 217         TALLOC_CTX *tmp_ctx = talloc_new(mem_ctx);
 218         struct security_acl *tmp_acl = talloc_zero(tmp_ctx, struct security_acl);
 219         struct security_acl *new_acl;
 220         struct dom_sid *co, *cg;
 221
 222         if (!acl)
 223                 return NULL;
 224
 225         if (!tmp_acl)
 226                 return NULL;
 227
 228         tmp_acl->revision = acl->revision;
 229         DEBUG(6,(__location__ ": acl revision %d\n", acl->revision));
 230
 231         co = dom_sid_parse_talloc(tmp_ctx,  SID_CREATOR_OWNER);
 232         cg = dom_sid_parse_talloc(tmp_ctx,  SID_CREATOR_GROUP);
 233
 234         for (i=0; i < acl->num_aces; i++){
 235                 struct security_ace *ace = &acl->aces[i];
 236                 /* Remove ID flags from user-provided ACEs
 237                  * if we break inheritance, ignore them otherwise */
 238                 if (ace->flags & SEC_ACE_FLAG_INHERITED_ACE) {
 239                         if (is_protected) {
 240                                 ace->flags &= ~SEC_ACE_FLAG_INHERITED_ACE;
 241                         } else {
 242                                 continue;
 243                         }
 244                 }
 245
 246                 if (ace->flags & SEC_ACE_FLAG_INHERIT_ONLY &&
 247                     !(ace->flags & SEC_ACE_FLAG_CONTAINER_INHERIT ||
 248                       ace->flags & SEC_ACE_FLAG_OBJECT_INHERIT))
 249                         continue;
 250
 251                 tmp_acl->aces = talloc_realloc(tmp_acl,
 252                                                tmp_acl->aces,
 253                                                struct security_ace,
 254                                                tmp_acl->num_aces+1);
 255                 tmp_acl->aces[tmp_acl->num_aces] = *ace;
 256                 tmp_acl->num_aces++;
 257                 if (ace->flags & SEC_ACE_FLAG_INHERIT_ONLY) {
 258                         continue;
 259                 }
 260                 /* if the ACE contains CO, CG, GA, GE, GR or GW, and is inheritable
 261                  * it has to be expanded to two aces, the original as IO,
 262                  * and another one where these are translated */
 263                 if (desc_ace_has_generic(tmp_ctx, ace)) {
 264                         if (!(ace->flags & SEC_ACE_FLAG_CONTAINER_INHERIT)) {
 265                                 desc_expand_generic(tmp_ctx,
 266                                                     &tmp_acl->aces[tmp_acl->num_aces-1],
 267                                                     owner,
 268                                                     group);
 269                         } else {
 270                                 /*The original ACE becomes read only */
 271                                 tmp_acl->aces[tmp_acl->num_aces-1].flags |= SEC_ACE_FLAG_INHERIT_ONLY;
 272                                 tmp_acl->aces = talloc_realloc(tmp_acl, tmp_acl->aces,
 273                                                                struct security_ace,
 274                                                                tmp_acl->num_aces+1);
 275                                 /* add a new ACE with expanded generic info */
 276                                 tmp_acl->aces[tmp_acl->num_aces] = *ace;
 277                                 desc_expand_generic(tmp_ctx,
 278                                                     &tmp_acl->aces[tmp_acl->num_aces],
 279                                                     owner,
 280                                                     group);
 281                                 tmp_acl->num_aces++;
 282                         }
 283                 }
 284         }
 285         new_acl = security_acl_dup(mem_ctx,tmp_acl);
 286
 287         if (new_acl)
 288                 new_acl->revision = acl->revision;
 289
 290         talloc_free(tmp_ctx);
 291         return new_acl;
 292 }
 293
 294 static void cr_descr_log_descriptor(struct security_descriptor *sd,
 295                                     const char *message,
 296                                     int level)
 297 {
 298         if (sd) {
 299                 DEBUG(level,("%s: %s\n", message,
 300                              ndr_print_struct_string(0,(ndr_print_fn_t)ndr_print_security_descriptor,
 301                                                      "", sd)));
 302         }
 303         else {
 304                 DEBUG(level,("%s: NULL\n", message));
 305         }
 306 }
 307
 308 #if 0
 309 static void cr_descr_log_acl(struct security_acl *acl,
 310                                     const char *message,
 311                                     int level)
 312 {
 313         if (acl) {
 314                 DEBUG(level,("%s: %s\n", message,
 315                              ndr_print_struct_string(0,(ndr_print_fn_t)ndr_print_security_acl,
 316                                                      "", acl)));
 317         }
 318         else {
 319                 DEBUG(level,("%s: NULL\n", message));
 320         }
 321 }
 322 #endif
 323
 324 static bool compute_acl(struct security_descriptor *parent_sd,
 325                         struct security_descriptor *creator_sd,
 326                         bool is_container,
 327                         uint32_t inherit_flags,
 328                         struct GUID *object_list,
 329                         uint32_t (*generic_map)(uint32_t access_mask),
 330                         struct security_token *token,
 331                         struct security_descriptor *new_sd) /* INOUT argument */
 332 {
 333         struct security_acl *user_dacl, *user_sacl, *inherited_dacl, *inherited_sacl;
 334         int level = 10;
 335
 336         if (!parent_sd || !(inherit_flags & SEC_DACL_AUTO_INHERIT)) {
 337                 inherited_dacl = NULL;
 338         } else if (creator_sd && (creator_sd->type & SEC_DESC_DACL_PROTECTED)) {
 339                 inherited_dacl = NULL;
 340         } else {
 341                 inherited_dacl = calculate_inherited_from_parent(new_sd,
 342                                                                  parent_sd->dacl,
 343                                                                  is_container,
 344                                                                  new_sd->owner_sid,
 345                                                                  new_sd->group_sid,
 346                                                                  object_list);
 347         }
 348
 349
 350         if (!parent_sd || !(inherit_flags & SEC_SACL_AUTO_INHERIT)) {
 351                 inherited_sacl = NULL;
 352         } else if (creator_sd && (creator_sd->type & SEC_DESC_SACL_PROTECTED)) {
 353                 inherited_sacl = NULL;
 354         } else {
 355                 inherited_sacl = calculate_inherited_from_parent(new_sd,
 356                                                                  parent_sd->sacl,
 357                                                                  is_container,
 358                                                                  new_sd->owner_sid,
 359                                                                  new_sd->group_sid,
 360                                                                  object_list);
 361         }
 362
 363         if (!creator_sd || (inherit_flags & SEC_DEFAULT_DESCRIPTOR)) {
 364                 user_dacl = NULL;
 365                 user_sacl = NULL;
 366         } else {
 367                 user_dacl = process_user_acl(new_sd,
 368                                              creator_sd->dacl,
 369                                              is_container,
 370                                              new_sd->owner_sid,
 371                                              new_sd->group_sid,
 372                                              object_list,
 373                                              creator_sd->type & SEC_DESC_DACL_PROTECTED);
 374                 user_sacl = process_user_acl(new_sd,
 375                                              creator_sd->sacl,
 376                                              is_container,
 377                                              new_sd->owner_sid,
 378                                              new_sd->group_sid,
 379                                              object_list,
 380                                              creator_sd->type & SEC_DESC_SACL_PROTECTED);
 381         }
 382         cr_descr_log_descriptor(parent_sd, __location__"parent_sd", level);
 383         cr_descr_log_descriptor(creator_sd,__location__ "creator_sd", level);
 384
 385         new_sd->dacl = security_acl_concatenate(new_sd, user_dacl, inherited_dacl);
 386         if (new_sd->dacl) {
 387                 new_sd->type |= SEC_DESC_DACL_PRESENT;
 388         }
 389         if (inherited_dacl) {
 390                 new_sd->type |= SEC_DESC_DACL_AUTO_INHERITED;
 391         }
 392
 393         new_sd->sacl = security_acl_concatenate(new_sd, user_sacl, inherited_sacl);
 394         if (new_sd->sacl) {
 395                 new_sd->type |= SEC_DESC_SACL_PRESENT;
 396         }
 397         if (inherited_sacl) {
 398                 new_sd->type |= SEC_DESC_SACL_AUTO_INHERITED;
 399         }
 400         /* This is a hack to handle the fact that
 401          * apprantly any AI flag provided by the user is preserved */
 402         if (creator_sd)
 403                 new_sd->type |= creator_sd->type;
 404         cr_descr_log_descriptor(new_sd, __location__"final sd", level);
 405         return true;
 406 }
 407
 408 struct security_descriptor *create_security_descriptor(TALLOC_CTX *mem_ctx,
 409                                                        struct security_descriptor *parent_sd,
 410                                                        struct security_descriptor *creator_sd,
 411                                                        bool is_container,
 412                                                        struct GUID *object_list,
 413                                                        uint32_t inherit_flags,
 414                                                        struct security_token *token,
 415                                                        struct dom_sid *default_owner, /* valid only for DS, NULL for the other RSs */
 416                                                        struct dom_sid *default_group, /* valid only for DS, NULL for the other RSs */
 417                                                        uint32_t (*generic_map)(uint32_t access_mask))
 418 {
 419         struct security_descriptor *new_sd;
 420         struct dom_sid *new_owner = NULL;
 421         struct dom_sid *new_group = NULL;
 422
 423         new_sd = security_descriptor_initialise(mem_ctx);
 424         if (!new_sd) {
 425                 return NULL;
 426         }
 427
 428         if (!creator_sd || !creator_sd->owner_sid) {
 429                 if ((inherit_flags & SEC_OWNER_FROM_PARENT) && parent_sd) {
 430                         new_owner = parent_sd->owner_sid;
 431                 } else if (!default_owner) {
 432                         new_owner = &token->sids[PRIMARY_USER_SID_INDEX];
 433                 } else {
 434                         new_owner = default_owner;
 435                         new_sd->type |= SEC_DESC_OWNER_DEFAULTED;
 436                 }
 437         } else {
 438                 new_owner = creator_sd->owner_sid;
 439         }
 440
 441         if (!creator_sd || !creator_sd->group_sid){
 442                 if ((inherit_flags & SEC_GROUP_FROM_PARENT) && parent_sd) {
 443                         new_group = parent_sd->group_sid;
 444                 } else if (!default_group && token->num_sids > PRIMARY_GROUP_SID_INDEX) {
 445                         new_group = &token->sids[PRIMARY_GROUP_SID_INDEX];
 446                 } else if (!default_group) {
 447                         /* This will happen only for anonymous, which has no other groups */
 448                         new_group = &token->sids[PRIMARY_USER_SID_INDEX];
 449                 } else {
 450                         new_group = default_group;
 451                         new_sd->type |= SEC_DESC_GROUP_DEFAULTED;
 452                 }
 453         } else {
 454                 new_group = creator_sd->group_sid;
 455         }
 456
 457         new_sd->owner_sid = talloc_memdup(new_sd, new_owner, sizeof(struct dom_sid));
 458         new_sd->group_sid = talloc_memdup(new_sd, new_group, sizeof(struct dom_sid));
 459         if (!new_sd->owner_sid || !new_sd->group_sid){
 460                 talloc_free(new_sd);
 461                 return NULL;
 462         }
 463
 464         if (!compute_acl(parent_sd, creator_sd,
 465                          is_container, inherit_flags, object_list,
 466                          generic_map,token,new_sd)){
 467                 talloc_free(new_sd);
 468                 return NULL;
 469         }
 470
 471         return new_sd;
 472 }