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