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