src/bus-proxyd/bus-policy.c

   1 /*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
   2
   3 /***
   4   This file is part of systemd.
   5
   6   Copyright 2013 Lennart Poettering
   7
   8   systemd is free software; you can redistribute it and/or modify it
   9   under the terms of the GNU Lesser General Public License as published by
  10   the Free Software Foundation; either version 2.1 of the License, or
  11   (at your option) any later version.
  12
  13   systemd is distributed in the hope that it will be useful, but
  14   WITHOUT ANY WARRANTY; without even the implied warranty of
  15   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  16   Lesser General Public License for more details.
  17
  18   You should have received a copy of the GNU Lesser General Public License
  19   along with systemd; If not, see <http://www.gnu.org/licenses/>.
  20 ***/
  21
  22 #include "xml.h"
  23 #include "fileio.h"
  24 #include "strv.h"
  25 #include "conf-files.h"
  26 #include "bus-internal.h"
  27 #include "bus-message.h"
  28 #include "bus-policy.h"
  29
  30 static void policy_item_free(PolicyItem *i) {
  31         assert(i);
  32
  33         free(i->interface);
  34         free(i->member);
  35         free(i->error);
  36         free(i->name);
  37         free(i->path);
  38         free(i);
  39 }
  40
  41 DEFINE_TRIVIAL_CLEANUP_FUNC(PolicyItem*, policy_item_free);
  42
  43 static void item_append(PolicyItem *i, PolicyItem **list) {
  44
  45         PolicyItem *tail;
  46
  47         LIST_FIND_TAIL(items, *list, tail);
  48         LIST_INSERT_AFTER(items, *list, tail, i);
  49 }
  50
  51 static int file_load(Policy *p, const char *path) {
  52
  53         _cleanup_free_ char *c = NULL, *policy_user = NULL, *policy_group = NULL;
  54         _cleanup_(policy_item_freep) PolicyItem *i = NULL;
  55         void *xml_state = NULL;
  56         unsigned n_other = 0;
  57         const char *q;
  58         int r;
  59
  60         enum {
  61                 STATE_OUTSIDE,
  62                 STATE_BUSCONFIG,
  63                 STATE_POLICY,
  64                 STATE_POLICY_CONTEXT,
  65                 STATE_POLICY_USER,
  66                 STATE_POLICY_GROUP,
  67                 STATE_POLICY_OTHER_ATTRIBUTE,
  68                 STATE_ALLOW_DENY,
  69                 STATE_ALLOW_DENY_INTERFACE,
  70                 STATE_ALLOW_DENY_MEMBER,
  71                 STATE_ALLOW_DENY_ERROR,
  72                 STATE_ALLOW_DENY_PATH,
  73                 STATE_ALLOW_DENY_MESSAGE_TYPE,
  74                 STATE_ALLOW_DENY_NAME,
  75                 STATE_ALLOW_DENY_OTHER_ATTRIBUTE,
  76                 STATE_OTHER,
  77         } state = STATE_OUTSIDE;
  78
  79         enum {
  80                 POLICY_CATEGORY_NONE,
  81                 POLICY_CATEGORY_DEFAULT,
  82                 POLICY_CATEGORY_MANDATORY,
  83                 POLICY_CATEGORY_USER,
  84                 POLICY_CATEGORY_GROUP
  85         } policy_category = POLICY_CATEGORY_NONE;
  86
  87         unsigned line = 0;
  88
  89         assert(p);
  90
  91         r = read_full_file(path, &c, NULL);
  92         if (r < 0) {
  93                 if (r == -ENOENT)
  94                         return 0;
  95                 if (r == -EISDIR)
  96                         return r;
  97
  98                 log_error("Failed to load %s: %s", path, strerror(-r));
  99                 return r;
 100         }
 101
 102         q = c;
 103         for (;;) {
 104                 _cleanup_free_ char *name = NULL;
 105                 int t;
 106
 107                 t = xml_tokenize(&q, &name, &xml_state, &line);
 108                 if (t < 0) {
 109                         log_error("XML parse failure in %s: %s", path, strerror(-t));
 110                         return t;
 111                 }
 112
 113                 switch (state) {
 114
 115                 case STATE_OUTSIDE:
 116
 117                         if (t == XML_TAG_OPEN) {
 118                                 if (streq(name, "busconfig"))
 119                                         state = STATE_BUSCONFIG;
 120                                 else {
 121                                         log_error("Unexpected tag %s at %s:%u.", name, path, line);
 122                                         return -EINVAL;
 123                                 }
 124
 125                         } else if (t == XML_END)
 126                                 return 0;
 127                         else if (t != XML_TEXT || !in_charset(name, WHITESPACE)) {
 128                                 log_error("Unexpected token (1) at %s:%u.", path, line);
 129                                 return -EINVAL;
 130                         }
 131
 132                         break;
 133
 134                 case STATE_BUSCONFIG:
 135
 136                         if (t == XML_TAG_OPEN) {
 137                                 if (streq(name, "policy")) {
 138                                         state = STATE_POLICY;
 139                                         policy_category = POLICY_CATEGORY_NONE;
 140                                         free(policy_user);
 141                                         free(policy_group);
 142                                         policy_user = policy_group = NULL;
 143                                 } else {
 144                                         state = STATE_OTHER;
 145                                         n_other = 0;
 146                                 }
 147                         } else if (t == XML_TAG_CLOSE_EMPTY ||
 148                                    (t == XML_TAG_CLOSE && streq(name, "busconfig")))
 149                                 state = STATE_OUTSIDE;
 150                         else if (t != XML_TEXT || !in_charset(name, WHITESPACE)) {
 151                                 log_error("Unexpected token (2) at %s:%u.", path, line);
 152                                 return -EINVAL;
 153                         }
 154
 155                         break;
 156
 157                 case STATE_POLICY:
 158
 159                         if (t == XML_ATTRIBUTE_NAME) {
 160                                 if (streq(name, "context"))
 161                                         state = STATE_POLICY_CONTEXT;
 162                                 else if (streq(name, "user"))
 163                                         state = STATE_POLICY_USER;
 164                                 else if (streq(name, "group"))
 165                                         state = STATE_POLICY_GROUP;
 166                                 else {
 167                                         if (streq(name, "at_console"))
 168                                                 log_debug("Attribute %s of <policy> tag unsupported at %s:%u, ignoring.", name, path, line);
 169                                         else
 170                                                 log_warning("Attribute %s of <policy> tag unknown at %s:%u, ignoring.", name, path, line);
 171                                         state = STATE_POLICY_OTHER_ATTRIBUTE;
 172                                 }
 173                         } else if (t == XML_TAG_CLOSE_EMPTY ||
 174                                    (t == XML_TAG_CLOSE && streq(name, "policy")))
 175                                 state = STATE_BUSCONFIG;
 176                         else if (t == XML_TAG_OPEN) {
 177                                 PolicyItemType it;
 178
 179                                 if (streq(name, "allow"))
 180                                         it = POLICY_ITEM_ALLOW;
 181                                 else if (streq(name, "deny"))
 182                                         it = POLICY_ITEM_DENY;
 183                                 else {
 184                                         log_warning("Unknown tag %s in <policy> %s:%u.", name, path, line);
 185                                         return -EINVAL;
 186                                 }
 187
 188                                 assert(!i);
 189                                 i = new0(PolicyItem, 1);
 190                                 if (!i)
 191                                         return log_oom();
 192
 193                                 i->type = it;
 194                                 state = STATE_ALLOW_DENY;
 195
 196                         } else if (t != XML_TEXT || !in_charset(name, WHITESPACE)) {
 197                                 log_error("Unexpected token (3) at %s:%u.", path, line);
 198                                 return -EINVAL;
 199                         }
 200
 201                         break;
 202
 203                 case STATE_POLICY_CONTEXT:
 204
 205                         if (t == XML_ATTRIBUTE_VALUE) {
 206                                 if (streq(name, "default")) {
 207                                         policy_category = POLICY_CATEGORY_DEFAULT;
 208                                         state = STATE_POLICY;
 209                                 } else if (streq(name, "mandatory")) {
 210                                         policy_category = POLICY_CATEGORY_MANDATORY;
 211                                         state = STATE_POLICY;
 212                                 } else {
 213                                         log_error("context= parameter %s unknown for <policy> at %s:%u.", name, path, line);
 214                                         return -EINVAL;
 215                                 }
 216                         } else {
 217                                 log_error("Unexpected token (4) at %s:%u.", path, line);
 218                                 return -EINVAL;
 219                         }
 220
 221                         break;
 222
 223                 case STATE_POLICY_USER:
 224
 225                         if (t == XML_ATTRIBUTE_VALUE) {
 226                                 free(policy_user);
 227                                 policy_user = name;
 228                                 name = NULL;
 229                                 policy_category = POLICY_CATEGORY_USER;
 230                                 state = STATE_POLICY;
 231                         } else {
 232                                 log_error("Unexpected token (5) in %s:%u.", path, line);
 233                                 return -EINVAL;
 234                         }
 235
 236                         break;
 237
 238                 case STATE_POLICY_GROUP:
 239
 240                         if (t == XML_ATTRIBUTE_VALUE) {
 241                                 free(policy_group);
 242                                 policy_group = name;
 243                                 name = NULL;
 244                                 policy_category = POLICY_CATEGORY_GROUP;
 245                                 state = STATE_POLICY;
 246                         } else {
 247                                 log_error("Unexpected token (6) at %s:%u.", path, line);
 248                                 return -EINVAL;
 249                         }
 250
 251                         break;
 252
 253                 case STATE_POLICY_OTHER_ATTRIBUTE:
 254
 255                         if (t == XML_ATTRIBUTE_VALUE)
 256                                 state = STATE_POLICY;
 257                         else {
 258                                 log_error("Unexpected token (7) in %s:%u.", path, line);
 259                                 return -EINVAL;
 260                         }
 261
 262                         break;
 263
 264                 case STATE_ALLOW_DENY:
 265
 266                         assert(i);
 267
 268                         if (t == XML_ATTRIBUTE_NAME) {
 269                                 PolicyItemClass ic;
 270
 271                                 if (startswith(name, "send_"))
 272                                         ic = POLICY_ITEM_SEND;
 273                                 else if (startswith(name, "receive_"))
 274                                         ic = POLICY_ITEM_RECV;
 275                                 else if (streq(name, "own"))
 276                                         ic = POLICY_ITEM_OWN;
 277                                 else if (streq(name, "own_prefix"))
 278                                         ic = POLICY_ITEM_OWN_PREFIX;
 279                                 else if (streq(name, "user"))
 280                                         ic = POLICY_ITEM_USER;
 281                                 else if (streq(name, "group"))
 282                                         ic = POLICY_ITEM_GROUP;
 283                                 else if (streq(name, "eavesdrop")) {
 284                                         log_debug("Unsupported attribute %s= at %s:%u, ignoring.", name, path, line);
 285                                         i->class = POLICY_ITEM_IGNORE;
 286                                         state = STATE_ALLOW_DENY_OTHER_ATTRIBUTE;
 287                                         break;
 288                                 } else {
 289                                         log_error("Unknown attribute %s= at %s:%u, ignoring.", name, path, line);
 290                                         state = STATE_ALLOW_DENY_OTHER_ATTRIBUTE;
 291                                         break;
 292                                 }
 293
 294                                 if (i->class != _POLICY_ITEM_CLASS_UNSET && ic != i->class) {
 295                                         log_error("send_ and receive_ fields mixed on same tag at %s:%u.", path, line);
 296                                         return -EINVAL;
 297                                 }
 298
 299                                 i->class = ic;
 300
 301                                 if (ic == POLICY_ITEM_SEND || ic == POLICY_ITEM_RECV) {
 302                                         const char *u;
 303
 304                                         u = strchr(name, '_');
 305                                         assert(u);
 306
 307                                         u++;
 308
 309                                         if (streq(u, "interface"))
 310                                                 state = STATE_ALLOW_DENY_INTERFACE;
 311                                         else if (streq(u, "member"))
 312                                                 state = STATE_ALLOW_DENY_MEMBER;
 313                                         else if (streq(u, "error"))
 314                                                 state = STATE_ALLOW_DENY_ERROR;
 315                                         else if (streq(u, "path"))
 316                                                 state = STATE_ALLOW_DENY_PATH;
 317                                         else if (streq(u, "type"))
 318                                                 state = STATE_ALLOW_DENY_MESSAGE_TYPE;
 319                                         else if ((streq(u, "destination") && ic == POLICY_ITEM_SEND) ||
 320                                                  (streq(u, "sender") && ic == POLICY_ITEM_RECV))
 321                                                 state = STATE_ALLOW_DENY_NAME;
 322                                         else {
 323                                                 if (streq(u, "requested_reply"))
 324                                                         log_debug("Unsupported attribute %s= at %s:%u, ignoring.", name, path, line);
 325                                                 else
 326                                                         log_error("Unknown attribute %s= at %s:%u, ignoring.", name, path, line);
 327                                                 state = STATE_ALLOW_DENY_OTHER_ATTRIBUTE;
 328                                                 break;
 329                                         }
 330                                 } else
 331                                         state = STATE_ALLOW_DENY_NAME;
 332
 333                         } else if (t == XML_TAG_CLOSE_EMPTY ||
 334                                    (t == XML_TAG_CLOSE && streq(name, i->type == POLICY_ITEM_ALLOW ? "allow" : "deny"))) {
 335
 336                                 if (i->class == _POLICY_ITEM_CLASS_UNSET) {
 337                                         log_error("Policy not set at %s:%u.", path, line);
 338                                         return -EINVAL;
 339                                 }
 340
 341                                 if (policy_category == POLICY_CATEGORY_DEFAULT)
 342                                         item_append(i, &p->default_items);
 343                                 else if (policy_category == POLICY_CATEGORY_MANDATORY)
 344                                         item_append(i, &p->mandatory_items);
 345                                 else if (policy_category == POLICY_CATEGORY_USER) {
 346                                         const char *u = policy_user;
 347
 348                                         assert_cc(sizeof(uid_t) == sizeof(uint32_t));
 349
 350                                         r = hashmap_ensure_allocated(&p->user_items, NULL);
 351                                         if (r < 0)
 352                                                 return log_oom();
 353
 354                                         if (!u) {
 355                                                 log_error("User policy without name");
 356                                                 return -EINVAL;
 357                                         }
 358
 359                                         r = get_user_creds(&u, &i->uid, NULL, NULL, NULL);
 360                                         if (r < 0) {
 361                                                 log_error("Failed to resolve user %s, ignoring policy: %s", u, strerror(-r));
 362                                                 free(i);
 363                                         } else {
 364                                                 PolicyItem *first;
 365
 366                                                 first = hashmap_get(p->user_items, UINT32_TO_PTR(i->uid));
 367                                                 item_append(i, &first);
 368                                                 i->uid_valid = true;
 369
 370                                                 r = hashmap_replace(p->user_items, UINT32_TO_PTR(i->uid), first);
 371                                                 if (r < 0) {
 372                                                         LIST_REMOVE(items, first, i);
 373                                                         return log_oom();
 374                                                 }
 375                                         }
 376
 377                                 } else if (policy_category == POLICY_CATEGORY_GROUP) {
 378                                         const char *g = policy_group;
 379
 380                                         assert_cc(sizeof(gid_t) == sizeof(uint32_t));
 381
 382                                         r = hashmap_ensure_allocated(&p->group_items, NULL);
 383                                         if (r < 0)
 384                                                 return log_oom();
 385
 386                                         if (!g) {
 387                                                 log_error("Group policy without name");
 388                                                 return -EINVAL;
 389                                         }
 390
 391                                         r = get_group_creds(&g, &i->gid);
 392                                         if (r < 0) {
 393                                                 log_error("Failed to resolve group %s, ignoring policy: %s", g, strerror(-r));
 394                                                 free(i);
 395                                         } else {
 396                                                 PolicyItem *first;
 397
 398                                                 first = hashmap_get(p->group_items, UINT32_TO_PTR(i->gid));
 399                                                 item_append(i, &first);
 400                                                 i->gid_valid = true;
 401
 402                                                 r = hashmap_replace(p->group_items, UINT32_TO_PTR(i->gid), first);
 403                                                 if (r < 0) {
 404                                                         LIST_REMOVE(items, first, i);
 405                                                         return log_oom();
 406                                                 }
 407                                         }
 408                                 }
 409
 410                                 state = STATE_POLICY;
 411                                 i = NULL;
 412
 413                         } else if (t != XML_TEXT || !in_charset(name, WHITESPACE)) {
 414                                 log_error("Unexpected token (8) at %s:%u.", path, line);
 415                                 return -EINVAL;
 416                         }
 417
 418                         break;
 419
 420                 case STATE_ALLOW_DENY_INTERFACE:
 421
 422                         if (t == XML_ATTRIBUTE_VALUE) {
 423                                 assert(i);
 424                                 if (i->interface) {
 425                                         log_error("Duplicate interface at %s:%u.", path, line);
 426                                         return -EINVAL;
 427                                 }
 428
 429                                 i->interface = name;
 430                                 name = NULL;
 431                                 state = STATE_ALLOW_DENY;
 432                         } else {
 433                                 log_error("Unexpected token (9) at %s:%u.", path, line);
 434                                 return -EINVAL;
 435                         }
 436
 437                         break;
 438
 439                 case STATE_ALLOW_DENY_MEMBER:
 440
 441                         if (t == XML_ATTRIBUTE_VALUE) {
 442                                 assert(i);
 443                                 if (i->member) {
 444                                         log_error("Duplicate member in %s:%u.", path, line);
 445                                         return -EINVAL;
 446                                 }
 447
 448                                 i->member = name;
 449                                 name = NULL;
 450                                 state = STATE_ALLOW_DENY;
 451                         } else {
 452                                 log_error("Unexpected token (10) in %s:%u.", path, line);
 453                                 return -EINVAL;
 454                         }
 455
 456                         break;
 457
 458                 case STATE_ALLOW_DENY_ERROR:
 459
 460                         if (t == XML_ATTRIBUTE_VALUE) {
 461                                 assert(i);
 462                                 if (i->error) {
 463                                         log_error("Duplicate error in %s:%u.", path, line);
 464                                         return -EINVAL;
 465                                 }
 466
 467                                 i->error = name;
 468                                 name = NULL;
 469                                 state = STATE_ALLOW_DENY;
 470                         } else {
 471                                 log_error("Unexpected token (11) in %s:%u.", path, line);
 472                                 return -EINVAL;
 473                         }
 474
 475                         break;
 476
 477                 case STATE_ALLOW_DENY_PATH:
 478
 479                         if (t == XML_ATTRIBUTE_VALUE) {
 480                                 assert(i);
 481                                 if (i->path) {
 482                                         log_error("Duplicate path in %s:%u.", path, line);
 483                                         return -EINVAL;
 484                                 }
 485
 486                                 i->path = name;
 487                                 name = NULL;
 488                                 state = STATE_ALLOW_DENY;
 489                         } else {
 490                                 log_error("Unexpected token (12) in %s:%u.", path, line);
 491                                 return -EINVAL;
 492                         }
 493
 494                         break;
 495
 496                 case STATE_ALLOW_DENY_MESSAGE_TYPE:
 497
 498                         if (t == XML_ATTRIBUTE_VALUE) {
 499                                 assert(i);
 500
 501                                 if (i->message_type != 0) {
 502                                         log_error("Duplicate message type in %s:%u.", path, line);
 503                                         return -EINVAL;
 504                                 }
 505
 506                                 r = bus_message_type_from_string(name, &i->message_type);
 507                                 if (r < 0) {
 508                                         log_error("Invalid message type in %s:%u.", path, line);
 509                                         return -EINVAL;
 510                                 }
 511
 512                                 state = STATE_ALLOW_DENY;
 513                         } else {
 514                                 log_error("Unexpected token (13) in %s:%u.", path, line);
 515                                 return -EINVAL;
 516                         }
 517
 518                         break;
 519
 520                 case STATE_ALLOW_DENY_NAME:
 521
 522                         if (t == XML_ATTRIBUTE_VALUE) {
 523                                 assert(i);
 524                                 if (i->name) {
 525                                         log_error("Duplicate name in %s:%u.", path, line);
 526                                         return -EINVAL;
 527                                 }
 528
 529                                 switch (i->class) {
 530                                 case POLICY_ITEM_USER:
 531                                         if (!streq(name, "*")) {
 532                                                 const char *u = name;
 533
 534                                                 r = get_user_creds(&u, &i->uid, NULL, NULL, NULL);
 535                                                 if (r < 0)
 536                                                         log_error("Failed to resolve user %s: %s", name, strerror(-r));
 537                                                 else
 538                                                         i->uid_valid = true;
 539                                         }
 540                                         break;
 541                                 case POLICY_ITEM_GROUP:
 542                                         if (!streq(name, "*")) {
 543                                                 const char *g = name;
 544
 545                                                 r = get_group_creds(&g, &i->gid);
 546                                                 if (r < 0)
 547                                                         log_error("Failed to resolve group %s: %s", name, strerror(-r));
 548                                                 else
 549                                                         i->gid_valid = true;
 550                                         }
 551                                         break;
 552                                 default:
 553                                         break;
 554                                 }
 555
 556                                 i->name = name;
 557                                 name = NULL;
 558
 559                                 state = STATE_ALLOW_DENY;
 560                         } else {
 561                                 log_error("Unexpected token (14) in %s:%u.", path, line);
 562                                 return -EINVAL;
 563                         }
 564
 565                         break;
 566
 567                 case STATE_ALLOW_DENY_OTHER_ATTRIBUTE:
 568
 569                         if (t == XML_ATTRIBUTE_VALUE)
 570                                 state = STATE_ALLOW_DENY;
 571                         else {
 572                                 log_error("Unexpected token (15) in %s:%u.", path, line);
 573                                 return -EINVAL;
 574                         }
 575
 576                         break;
 577
 578                 case STATE_OTHER:
 579
 580                         if (t == XML_TAG_OPEN)
 581                                 n_other++;
 582                         else if (t == XML_TAG_CLOSE || t == XML_TAG_CLOSE_EMPTY) {
 583
 584                                 if (n_other == 0)
 585                                         state = STATE_BUSCONFIG;
 586                                 else
 587                                         n_other--;
 588                         }
 589
 590                         break;
 591                 }
 592         }
 593 }
 594
 595 enum {
 596         ALLOW,
 597         DUNNO,
 598         DENY,
 599 };
 600
 601 struct policy_check_filter {
 602         int class;
 603         const struct ucred *ucred;
 604         int message_type;
 605         const char *name;
 606         const char *interface;
 607         const char *path;
 608         const char *member;
 609 };
 610
 611 static int is_permissive(PolicyItem *i) {
 612
 613         assert(i);
 614
 615         return (i->type == POLICY_ITEM_ALLOW) ? ALLOW : DENY;
 616 }
 617
 618 static int check_policy_item(PolicyItem *i, const struct policy_check_filter *filter) {
 619
 620         assert(i);
 621         assert(filter);
 622
 623         switch (i->class) {
 624         case POLICY_ITEM_SEND:
 625         case POLICY_ITEM_RECV:
 626
 627                 if (i->name && !streq_ptr(i->name, filter->name))
 628                         break;
 629
 630                 if ((i->message_type != _POLICY_ITEM_CLASS_UNSET) && (i->message_type != filter->message_type))
 631                         break;
 632
 633                 if (i->path && !streq_ptr(i->path, filter->path))
 634                         break;
 635
 636                 if (i->member && !streq_ptr(i->member, filter->member))
 637                         break;
 638
 639                 if (i->interface && !streq_ptr(i->interface, filter->interface))
 640                         break;
 641
 642                 return is_permissive(i);
 643
 644         case POLICY_ITEM_OWN:
 645                 assert(filter->name);
 646
 647                 if (streq(i->name, "*") || streq(i->name, filter->name))
 648                         return is_permissive(i);
 649                 break;
 650
 651         case POLICY_ITEM_OWN_PREFIX:
 652                 assert(filter->name);
 653
 654                 if (streq(i->name, "*") || startswith(i->name, filter->name))
 655                         return is_permissive(i);
 656                 break;
 657
 658         case POLICY_ITEM_USER:
 659                 assert(filter->ucred);
 660
 661                 if ((streq_ptr(i->name, "*") || (i->uid_valid && i->uid == filter->ucred->uid)))
 662                         return is_permissive(i);
 663                 break;
 664
 665         case POLICY_ITEM_GROUP:
 666                 assert(filter->ucred);
 667
 668                 if ((streq_ptr(i->name, "*") || (i->gid_valid && i->gid == filter->ucred->gid)))
 669                         return is_permissive(i);
 670                 break;
 671
 672         case POLICY_ITEM_IGNORE:
 673         default:
 674                 break;
 675         }
 676
 677         return DUNNO;
 678 }
 679
 680 static int check_policy_items(PolicyItem *items, const struct policy_check_filter *filter) {
 681
 682         PolicyItem *i;
 683         int r, ret = DUNNO;
 684
 685         assert(filter);
 686
 687         /* Check all policies in a set - a broader one might be followed by a more specific one,
 688          * and the order of rules in policy definitions matters */
 689         LIST_FOREACH(items, i, items) {
 690                 if (i->class != filter->class)
 691                         continue;
 692
 693                 r = check_policy_item(i, filter);
 694                 if (r != DUNNO)
 695                         ret = r;
 696         }
 697
 698         return ret;
 699 }
 700
 701 static int policy_check(Policy *p, const struct policy_check_filter *filter) {
 702
 703         PolicyItem *items;
 704         int r;
 705
 706         assert(p);
 707         assert(filter);
 708
 709         /*
 710          * The policy check is implemented by the following logic:
 711          *
 712          * 1. Check mandatory items. If the message matches any of these, it is decisive.
 713          * 2. See if the passed ucred match against the user/group hashmaps. A matching entry is also decisive.
 714          * 3. Consult the defaults if non of the above matched with a more specific rule.
 715          * 4. If the message isn't caught be the defaults either, reject it.
 716          */
 717
 718         r = check_policy_items(p->mandatory_items, filter);
 719         if (r != DUNNO)
 720                 return r;
 721
 722         if (filter->ucred) {
 723                 items = hashmap_get(p->user_items, UINT32_TO_PTR(filter->ucred->uid));
 724                 if (items) {
 725                         r = check_policy_items(items, filter);
 726                         if (r != DUNNO)
 727                                 return r;
 728                 }
 729
 730                 items = hashmap_get(p->group_items, UINT32_TO_PTR(filter->ucred->gid));
 731                 if (items) {
 732                         r = check_policy_items(items, filter);
 733                         if (r != DUNNO)
 734                                 return r;
 735                 }
 736         }
 737
 738         return check_policy_items(p->default_items, filter);
 739 }
 740
 741 bool policy_check_own(Policy *p, const struct ucred *ucred, const char *name) {
 742
 743         struct policy_check_filter filter = {
 744                 .class = POLICY_ITEM_OWN,
 745                 .ucred = ucred,
 746                 .name  = name,
 747         };
 748
 749         return policy_check(p, &filter) == ALLOW;
 750 }
 751
 752 bool policy_check_hello(Policy *p, const struct ucred *ucred) {
 753
 754         struct policy_check_filter filter = {
 755                 .ucred  = ucred,
 756         };
 757         int user, group;
 758
 759         filter.class = POLICY_ITEM_USER;
 760         user = policy_check(p, &filter);
 761         if (user == DENY)
 762                 return false;
 763
 764         filter.class = POLICY_ITEM_GROUP;
 765         group = policy_check(p, &filter);
 766         if (group == DENY)
 767                 return false;
 768
 769         return !(user == DUNNO && group == DUNNO);
 770 }
 771
 772 bool policy_check_recv(Policy *p,
 773                        const struct ucred *ucred,
 774                        int message_type,
 775                        const char *name,
 776                        const char *path,
 777                        const char *interface,
 778                        const char *member) {
 779
 780         struct policy_check_filter filter = {
 781                 .class        = POLICY_ITEM_RECV,
 782                 .ucred        = ucred,
 783                 .message_type = message_type,
 784                 .name         = name,
 785                 .interface    = interface,
 786                 .path         = path,
 787                 .member       = member,
 788         };
 789
 790         return policy_check(p, &filter) == ALLOW;
 791 }
 792
 793 bool policy_check_send(Policy *p,
 794                        const struct ucred *ucred,
 795                        int message_type,
 796                        const char *name,
 797                        const char *path,
 798                        const char *interface,
 799                        const char *member) {
 800
 801         struct policy_check_filter filter = {
 802                 .class        = POLICY_ITEM_SEND,
 803                 .ucred        = ucred,
 804                 .message_type = message_type,
 805                 .name         = name,
 806                 .interface    = interface,
 807                 .path         = path,
 808                 .member       = member,
 809         };
 810
 811         return policy_check(p, &filter) == ALLOW;
 812 }
 813
 814 int policy_load(Policy *p, char **files) {
 815         char **i;
 816         int r;
 817
 818         assert(p);
 819
 820         STRV_FOREACH(i, files) {
 821
 822                 r = file_load(p, *i);
 823                 if (r == -EISDIR) {
 824                         _cleanup_strv_free_ char **l = NULL;
 825                         char **j;
 826
 827                         r = conf_files_list(&l, ".conf", NULL, *i, NULL);
 828                         if (r < 0) {
 829                                 log_error("Failed to get configuration file list: %s", strerror(-r));
 830                                 return r;
 831                         }
 832
 833                         STRV_FOREACH(j, l)
 834                                 file_load(p, *j);
 835                 }
 836
 837                 /* We ignore all errors but EISDIR, and just proceed. */
 838         }
 839
 840         return 0;
 841 }
 842
 843 void policy_free(Policy *p) {
 844         PolicyItem *i, *first;
 845
 846         if (!p)
 847                 return;
 848
 849         while ((i = p->default_items)) {
 850                 LIST_REMOVE(items, p->default_items, i);
 851                 policy_item_free(i);
 852         }
 853
 854         while ((i = p->mandatory_items)) {
 855                 LIST_REMOVE(items, p->mandatory_items, i);
 856                 policy_item_free(i);
 857         }
 858
 859         while ((first = hashmap_steal_first(p->user_items))) {
 860
 861                 while ((i = first)) {
 862                         LIST_REMOVE(items, first, i);
 863                         policy_item_free(i);
 864                 }
 865         }
 866
 867         while ((first = hashmap_steal_first(p->group_items))) {
 868
 869                 while ((i = first)) {
 870                         LIST_REMOVE(items, first, i);
 871                         policy_item_free(i);
 872                 }
 873         }
 874
 875         hashmap_free(p->user_items);
 876         hashmap_free(p->group_items);
 877
 878         p->user_items = p->group_items = NULL;
 879 }
 880
 881 static void dump_items(PolicyItem *items, const char *prefix) {
 882
 883         PolicyItem *i;
 884
 885         if (!items)
 886                 return;
 887
 888         if (!prefix)
 889                 prefix = "";
 890
 891         LIST_FOREACH(items, i, items) {
 892
 893                 printf("%sType: %s\n"
 894                        "%sClass: %s\n",
 895                        prefix, policy_item_type_to_string(i->type),
 896                        prefix, policy_item_class_to_string(i->class));
 897
 898                 if (i->interface)
 899                         printf("%sInterface: %s\n",
 900                                prefix, i->interface);
 901
 902                 if (i->member)
 903                         printf("%sMember: %s\n",
 904                                prefix, i->member);
 905
 906                 if (i->error)
 907                         printf("%sError: %s\n",
 908                                prefix, i->error);
 909
 910                 if (i->path)
 911                         printf("%sPath: %s\n",
 912                                prefix, i->path);
 913
 914                 if (i->name)
 915                         printf("%sName: %s\n",
 916                                prefix, i->name);
 917
 918                 if (i->message_type != 0)
 919                         printf("%sMessage Type: %s\n",
 920                                prefix, bus_message_type_to_string(i->message_type));
 921
 922                 if (i->uid_valid) {
 923                         _cleanup_free_ char *user;
 924
 925                         user = uid_to_name(i->uid);
 926
 927                         printf("%sUser: %s (%d)\n",
 928                                prefix, strna(user), i->uid);
 929                 }
 930
 931                 if (i->gid_valid) {
 932                         _cleanup_free_ char *group;
 933
 934                         group = gid_to_name(i->gid);
 935
 936                         printf("%sGroup: %s (%d)\n",
 937                                prefix, strna(group), i->gid);
 938                 }
 939         }
 940 }
 941
 942 static void dump_hashmap_items(Hashmap *h) {
 943         PolicyItem *i;
 944         Iterator j;
 945         void *k;
 946
 947         HASHMAP_FOREACH_KEY(i, k, h, j) {
 948                 printf("\t%s Item for %u:\n", draw_special_char(DRAW_ARROW), PTR_TO_UINT(k));
 949                 dump_items(i, "\t\t");
 950         }
 951 }
 952
 953 void policy_dump(Policy *p) {
 954
 955         printf("%s Default Items:\n", draw_special_char(DRAW_ARROW));
 956         dump_items(p->default_items, "\t");
 957
 958         printf("%s Group Items:\n", draw_special_char(DRAW_ARROW));
 959         dump_hashmap_items(p->group_items);
 960
 961         printf("%s User Items:\n", draw_special_char(DRAW_ARROW));
 962         dump_hashmap_items(p->user_items);
 963
 964         printf("%s Mandatory Items:\n", draw_special_char(DRAW_ARROW));
 965         dump_items(p->mandatory_items, "\t");
 966 }
 967
 968 static const char* const policy_item_type_table[_POLICY_ITEM_TYPE_MAX] = {
 969         [_POLICY_ITEM_TYPE_UNSET] = "unset",
 970         [POLICY_ITEM_ALLOW] = "allow",
 971         [POLICY_ITEM_DENY] = "deny",
 972 };
 973 DEFINE_STRING_TABLE_LOOKUP(policy_item_type, PolicyItemType);
 974
 975 static const char* const policy_item_class_table[_POLICY_ITEM_CLASS_MAX] = {
 976         [_POLICY_ITEM_CLASS_UNSET] = "unset",
 977         [POLICY_ITEM_SEND] = "send",
 978         [POLICY_ITEM_RECV] = "recv",
 979         [POLICY_ITEM_OWN] = "own",
 980         [POLICY_ITEM_OWN_PREFIX] = "own-prefix",
 981         [POLICY_ITEM_USER] = "user",
 982         [POLICY_ITEM_GROUP] = "group",
 983         [POLICY_ITEM_IGNORE] = "ignore",
 984 };
 985 DEFINE_STRING_TABLE_LOOKUP(policy_item_class, PolicyItemClass);