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