1 /* 2 * Implementation of the userspace access vector cache (AVC). 3 * 4 * Author : Eamon Walsh <ewalsh (at) epoch.ncsc.mil> 5 * 6 * Derived from the kernel AVC implementation by 7 * Stephen Smalley <sds (at) epoch.ncsc.mil> and 8 * James Morris <jmorris (at) redhat.com>. 9 */ 10 #include <selinux/avc.h> 11 #include "selinux_internal.h" 12 #include <assert.h> 13 #include "avc_sidtab.h" 14 #include "avc_internal.h" 15 16 #define AVC_CACHE_SLOTS 512 17 #define AVC_CACHE_MAXNODES 410 18 19 struct avc_entry { 20 security_id_t ssid; 21 security_id_t tsid; 22 security_class_t tclass; 23 struct av_decision avd; 24 security_id_t create_sid; 25 int used; /* used recently */ 26 }; 27 28 struct avc_node { 29 struct avc_entry ae; 30 struct avc_node *next; 31 }; 32 33 struct avc_cache { 34 struct avc_node *slots[AVC_CACHE_SLOTS]; 35 uint32_t lru_hint; /* LRU hint for reclaim scan */ 36 uint32_t active_nodes; 37 uint32_t latest_notif; /* latest revocation notification */ 38 }; 39 40 struct avc_callback_node { 41 int (*callback) (uint32_t event, security_id_t ssid, 42 security_id_t tsid, 43 security_class_t tclass, access_vector_t perms, 44 access_vector_t * out_retained); 45 uint32_t events; 46 security_id_t ssid; 47 security_id_t tsid; 48 security_class_t tclass; 49 access_vector_t perms; 50 struct avc_callback_node *next; 51 }; 52 53 static void *avc_netlink_thread = NULL; 54 static void *avc_lock = NULL; 55 static void *avc_log_lock = NULL; 56 static struct avc_node *avc_node_freelist = NULL; 57 static struct avc_cache avc_cache; 58 static char *avc_audit_buf = NULL; 59 static struct avc_cache_stats cache_stats; 60 static struct avc_callback_node *avc_callbacks = NULL; 61 static struct sidtab avc_sidtab; 62 63 static inline int avc_hash(security_id_t ssid, 64 security_id_t tsid, security_class_t tclass) 65 { 66 return ((uintptr_t) ssid ^ ((uintptr_t) tsid << 2) ^ tclass) 67 & (AVC_CACHE_SLOTS - 1); 68 } 69 70 int avc_context_to_sid_raw(const char * ctx, security_id_t * sid) 71 { 72 int rc; 73 /* avc_init needs to be called before this function */ 74 assert(avc_running); 75 76 avc_get_lock(avc_lock); 77 rc = sidtab_context_to_sid(&avc_sidtab, ctx, sid); 78 avc_release_lock(avc_lock); 79 return rc; 80 } 81 82 int avc_context_to_sid(const char * ctx, security_id_t * sid) 83 { 84 int ret; 85 char * rctx; 86 87 if (selinux_trans_to_raw_context(ctx, &rctx)) 88 return -1; 89 90 ret = avc_context_to_sid_raw(rctx, sid); 91 92 freecon(rctx); 93 94 return ret; 95 } 96 97 int avc_sid_to_context_raw(security_id_t sid, char ** ctx) 98 { 99 int rc; 100 *ctx = NULL; 101 avc_get_lock(avc_lock); 102 *ctx = strdup(sid->ctx); /* caller must free via freecon */ 103 rc = *ctx ? 0 : -1; 104 avc_release_lock(avc_lock); 105 return rc; 106 } 107 108 int avc_sid_to_context(security_id_t sid, char ** ctx) 109 { 110 int ret; 111 char * rctx; 112 113 ret = avc_sid_to_context_raw(sid, &rctx); 114 115 if (ret == 0) { 116 ret = selinux_raw_to_trans_context(rctx, ctx); 117 freecon(rctx); 118 } 119 120 return ret; 121 } 122 123 int sidget(security_id_t sid __attribute__((unused))) 124 { 125 return 1; 126 } 127 128 int sidput(security_id_t sid __attribute__((unused))) 129 { 130 return 1; 131 } 132 133 int avc_get_initial_sid(const char * name, security_id_t * sid) 134 { 135 int rc; 136 char * con; 137 138 rc = security_get_initial_context_raw(name, &con); 139 if (rc < 0) 140 return rc; 141 rc = avc_context_to_sid_raw(con, sid); 142 143 freecon(con); 144 145 return rc; 146 } 147 148 int avc_open(struct selinux_opt *opts, unsigned nopts) 149 { 150 avc_setenforce = 0; 151 152 while (nopts--) 153 switch(opts[nopts].type) { 154 case AVC_OPT_SETENFORCE: 155 avc_setenforce = 1; 156 avc_enforcing = !!opts[nopts].value; 157 break; 158 } 159 160 return avc_init("avc", NULL, NULL, NULL, NULL); 161 } 162 163 int avc_init(const char *prefix, 164 const struct avc_memory_callback *mem_cb, 165 const struct avc_log_callback *log_cb, 166 const struct avc_thread_callback *thread_cb, 167 const struct avc_lock_callback *lock_cb) 168 { 169 struct avc_node *new; 170 int i, rc = 0; 171 172 if (avc_running) 173 return 0; 174 175 if (prefix) 176 strncpy(avc_prefix, prefix, AVC_PREFIX_SIZE - 1); 177 178 set_callbacks(mem_cb, log_cb, thread_cb, lock_cb); 179 180 avc_lock = avc_alloc_lock(); 181 avc_log_lock = avc_alloc_lock(); 182 183 memset(&cache_stats, 0, sizeof(cache_stats)); 184 185 for (i = 0; i < AVC_CACHE_SLOTS; i++) 186 avc_cache.slots[i] = 0; 187 avc_cache.lru_hint = 0; 188 avc_cache.active_nodes = 0; 189 avc_cache.latest_notif = 0; 190 191 rc = sidtab_init(&avc_sidtab); 192 if (rc) { 193 avc_log(SELINUX_ERROR, 194 "%s: unable to initialize SID table\n", 195 avc_prefix); 196 goto out; 197 } 198 199 avc_audit_buf = (char *)avc_malloc(AVC_AUDIT_BUFSIZE); 200 if (!avc_audit_buf) { 201 avc_log(SELINUX_ERROR, 202 "%s: unable to allocate audit buffer\n", 203 avc_prefix); 204 rc = -1; 205 goto out; 206 } 207 208 for (i = 0; i < AVC_CACHE_MAXNODES; i++) { 209 new = avc_malloc(sizeof(*new)); 210 if (!new) { 211 avc_log(SELINUX_WARNING, 212 "%s: warning: only got %d av entries\n", 213 avc_prefix, i); 214 break; 215 } 216 memset(new, 0, sizeof(*new)); 217 new->next = avc_node_freelist; 218 avc_node_freelist = new; 219 } 220 221 if (!avc_setenforce) { 222 rc = security_getenforce(); 223 if (rc < 0) { 224 avc_log(SELINUX_ERROR, 225 "%s: could not determine enforcing mode: %s\n", 226 avc_prefix, 227 strerror(errno)); 228 goto out; 229 } 230 avc_enforcing = rc; 231 } 232 233 rc = avc_netlink_open(0); 234 if (rc < 0) { 235 avc_log(SELINUX_ERROR, 236 "%s: can't open netlink socket: %d (%s)\n", 237 avc_prefix, errno, strerror(errno)); 238 goto out; 239 } 240 if (avc_using_threads) { 241 avc_netlink_thread = avc_create_thread(&avc_netlink_loop); 242 avc_netlink_trouble = 0; 243 } 244 avc_running = 1; 245 out: 246 return rc; 247 } 248 249 void avc_cache_stats(struct avc_cache_stats *p) 250 { 251 memcpy(p, &cache_stats, sizeof(cache_stats)); 252 } 253 254 void avc_sid_stats(void) 255 { 256 /* avc_init needs to be called before this function */ 257 assert(avc_running); 258 avc_get_lock(avc_log_lock); 259 avc_get_lock(avc_lock); 260 sidtab_sid_stats(&avc_sidtab, avc_audit_buf, AVC_AUDIT_BUFSIZE); 261 avc_release_lock(avc_lock); 262 avc_log(SELINUX_INFO, "%s", avc_audit_buf); 263 avc_release_lock(avc_log_lock); 264 } 265 266 void avc_av_stats(void) 267 { 268 int i, chain_len, max_chain_len, slots_used; 269 struct avc_node *node; 270 271 avc_get_lock(avc_lock); 272 273 slots_used = 0; 274 max_chain_len = 0; 275 for (i = 0; i < AVC_CACHE_SLOTS; i++) { 276 node = avc_cache.slots[i]; 277 if (node) { 278 slots_used++; 279 chain_len = 0; 280 while (node) { 281 chain_len++; 282 node = node->next; 283 } 284 if (chain_len > max_chain_len) 285 max_chain_len = chain_len; 286 } 287 } 288 289 avc_release_lock(avc_lock); 290 291 avc_log(SELINUX_INFO, "%s: %u AV entries and %d/%d buckets used, " 292 "longest chain length %d\n", avc_prefix, 293 avc_cache.active_nodes, 294 slots_used, AVC_CACHE_SLOTS, max_chain_len); 295 } 296 297 hidden_def(avc_av_stats) 298 299 static inline struct avc_node *avc_reclaim_node(void) 300 { 301 struct avc_node *prev, *cur; 302 int try; 303 uint32_t hvalue; 304 305 hvalue = avc_cache.lru_hint; 306 for (try = 0; try < 2; try++) { 307 do { 308 prev = NULL; 309 cur = avc_cache.slots[hvalue]; 310 while (cur) { 311 if (!cur->ae.used) 312 goto found; 313 314 cur->ae.used = 0; 315 316 prev = cur; 317 cur = cur->next; 318 } 319 hvalue = (hvalue + 1) & (AVC_CACHE_SLOTS - 1); 320 } while (hvalue != avc_cache.lru_hint); 321 } 322 323 errno = ENOMEM; /* this was a panic in the kernel... */ 324 return NULL; 325 326 found: 327 avc_cache.lru_hint = hvalue; 328 329 if (prev == NULL) 330 avc_cache.slots[hvalue] = cur->next; 331 else 332 prev->next = cur->next; 333 334 return cur; 335 } 336 337 static inline void avc_clear_avc_entry(struct avc_entry *ae) 338 { 339 memset(ae, 0, sizeof(*ae)); 340 } 341 342 static inline struct avc_node *avc_claim_node(security_id_t ssid, 343 security_id_t tsid, 344 security_class_t tclass) 345 { 346 struct avc_node *new; 347 int hvalue; 348 349 if (!avc_node_freelist) 350 avc_cleanup(); 351 352 if (avc_node_freelist) { 353 new = avc_node_freelist; 354 avc_node_freelist = avc_node_freelist->next; 355 avc_cache.active_nodes++; 356 } else { 357 new = avc_reclaim_node(); 358 if (!new) 359 goto out; 360 } 361 362 hvalue = avc_hash(ssid, tsid, tclass); 363 avc_clear_avc_entry(&new->ae); 364 new->ae.used = 1; 365 new->ae.ssid = ssid; 366 new->ae.tsid = tsid; 367 new->ae.tclass = tclass; 368 new->next = avc_cache.slots[hvalue]; 369 avc_cache.slots[hvalue] = new; 370 371 out: 372 return new; 373 } 374 375 static inline struct avc_node *avc_search_node(security_id_t ssid, 376 security_id_t tsid, 377 security_class_t tclass, 378 int *probes) 379 { 380 struct avc_node *cur; 381 int hvalue; 382 int tprobes = 1; 383 384 hvalue = avc_hash(ssid, tsid, tclass); 385 cur = avc_cache.slots[hvalue]; 386 while (cur != NULL && 387 (ssid != cur->ae.ssid || 388 tclass != cur->ae.tclass || tsid != cur->ae.tsid)) { 389 tprobes++; 390 cur = cur->next; 391 } 392 393 if (cur == NULL) { 394 /* cache miss */ 395 goto out; 396 } 397 398 /* cache hit */ 399 if (probes) 400 *probes = tprobes; 401 402 cur->ae.used = 1; 403 404 out: 405 return cur; 406 } 407 408 /** 409 * avc_lookup - Look up an AVC entry. 410 * @ssid: source security identifier 411 * @tsid: target security identifier 412 * @tclass: target security class 413 * @requested: requested permissions, interpreted based on @tclass 414 * @aeref: AVC entry reference 415 * 416 * Look up an AVC entry that is valid for the 417 * @requested permissions between the SID pair 418 * (@ssid, @tsid), interpreting the permissions 419 * based on @tclass. If a valid AVC entry exists, 420 * then this function updates @aeref to refer to the 421 * entry and returns %0. Otherwise, -1 is returned. 422 */ 423 static int avc_lookup(security_id_t ssid, security_id_t tsid, 424 security_class_t tclass, 425 access_vector_t requested, struct avc_entry_ref *aeref) 426 { 427 struct avc_node *node; 428 int probes, rc = 0; 429 430 avc_cache_stats_incr(cav_lookups); 431 node = avc_search_node(ssid, tsid, tclass, &probes); 432 433 if (node && ((node->ae.avd.decided & requested) == requested)) { 434 avc_cache_stats_incr(cav_hits); 435 avc_cache_stats_add(cav_probes, probes); 436 aeref->ae = &node->ae; 437 goto out; 438 } 439 440 avc_cache_stats_incr(cav_misses); 441 rc = -1; 442 out: 443 return rc; 444 } 445 446 /** 447 * avc_insert - Insert an AVC entry. 448 * @ssid: source security identifier 449 * @tsid: target security identifier 450 * @tclass: target security class 451 * @ae: AVC entry 452 * @aeref: AVC entry reference 453 * 454 * Insert an AVC entry for the SID pair 455 * (@ssid, @tsid) and class @tclass. 456 * The access vectors and the sequence number are 457 * normally provided by the security server in 458 * response to a security_compute_av() call. If the 459 * sequence number @ae->avd.seqno is not less than the latest 460 * revocation notification, then the function copies 461 * the access vectors into a cache entry, updates 462 * @aeref to refer to the entry, and returns %0. 463 * Otherwise, this function returns -%1 with @errno set to %EAGAIN. 464 */ 465 static int avc_insert(security_id_t ssid, security_id_t tsid, 466 security_class_t tclass, 467 struct avc_entry *ae, struct avc_entry_ref *aeref) 468 { 469 struct avc_node *node; 470 int rc = 0; 471 472 if (ae->avd.seqno < avc_cache.latest_notif) { 473 avc_log(SELINUX_WARNING, 474 "%s: seqno %u < latest_notif %u\n", avc_prefix, 475 ae->avd.seqno, avc_cache.latest_notif); 476 errno = EAGAIN; 477 rc = -1; 478 goto out; 479 } 480 481 node = avc_claim_node(ssid, tsid, tclass); 482 if (!node) { 483 rc = -1; 484 goto out; 485 } 486 487 memcpy(&node->ae.avd, &ae->avd, sizeof(ae->avd)); 488 aeref->ae = &node->ae; 489 out: 490 return rc; 491 } 492 493 void avc_cleanup(void) 494 { 495 } 496 497 hidden_def(avc_cleanup) 498 499 int avc_reset(void) 500 { 501 struct avc_callback_node *c; 502 int i, ret, rc = 0, errsave = 0; 503 struct avc_node *node, *tmp; 504 errno = 0; 505 506 if (!avc_running) 507 return 0; 508 509 avc_get_lock(avc_lock); 510 511 for (i = 0; i < AVC_CACHE_SLOTS; i++) { 512 node = avc_cache.slots[i]; 513 while (node) { 514 tmp = node; 515 node = node->next; 516 avc_clear_avc_entry(&tmp->ae); 517 tmp->next = avc_node_freelist; 518 avc_node_freelist = tmp; 519 avc_cache.active_nodes--; 520 } 521 avc_cache.slots[i] = 0; 522 } 523 avc_cache.lru_hint = 0; 524 525 avc_release_lock(avc_lock); 526 527 memset(&cache_stats, 0, sizeof(cache_stats)); 528 529 for (c = avc_callbacks; c; c = c->next) { 530 if (c->events & AVC_CALLBACK_RESET) { 531 ret = c->callback(AVC_CALLBACK_RESET, 0, 0, 0, 0, 0); 532 if (ret && !rc) { 533 rc = ret; 534 errsave = errno; 535 } 536 } 537 } 538 errno = errsave; 539 return rc; 540 } 541 542 hidden_def(avc_reset) 543 544 void avc_destroy(void) 545 { 546 struct avc_callback_node *c; 547 struct avc_node *node, *tmp; 548 int i; 549 /* avc_init needs to be called before this function */ 550 assert(avc_running); 551 552 avc_get_lock(avc_lock); 553 554 if (avc_using_threads) 555 avc_stop_thread(avc_netlink_thread); 556 avc_netlink_close(); 557 558 for (i = 0; i < AVC_CACHE_SLOTS; i++) { 559 node = avc_cache.slots[i]; 560 while (node) { 561 tmp = node; 562 node = node->next; 563 avc_free(tmp); 564 } 565 } 566 while (avc_node_freelist) { 567 tmp = avc_node_freelist; 568 avc_node_freelist = tmp->next; 569 avc_free(tmp); 570 } 571 avc_release_lock(avc_lock); 572 573 while (avc_callbacks) { 574 c = avc_callbacks; 575 avc_callbacks = c->next; 576 avc_free(c); 577 } 578 sidtab_destroy(&avc_sidtab); 579 avc_free_lock(avc_lock); 580 avc_free_lock(avc_log_lock); 581 avc_free(avc_audit_buf); 582 avc_running = 0; 583 } 584 585 /* ratelimit stuff put aside for now --EFW */ 586 #if 0 587 /* 588 * Copied from net/core/utils.c:net_ratelimit and modified for 589 * use by the AVC audit facility. 590 */ 591 #define AVC_MSG_COST 5*HZ 592 #define AVC_MSG_BURST 10*5*HZ 593 594 /* 595 * This enforces a rate limit: not more than one kernel message 596 * every 5secs to make a denial-of-service attack impossible. 597 */ 598 static int avc_ratelimit(void) 599 { 600 static unsigned long toks = 10 * 5 * HZ; 601 static unsigned long last_msg; 602 static int missed, rc = 0; 603 unsigned long now = jiffies; 604 void *ratelimit_lock = avc_alloc_lock(); 605 606 avc_get_lock(ratelimit_lock); 607 toks += now - last_msg; 608 last_msg = now; 609 if (toks > AVC_MSG_BURST) 610 toks = AVC_MSG_BURST; 611 if (toks >= AVC_MSG_COST) { 612 int lost = missed; 613 missed = 0; 614 toks -= AVC_MSG_COST; 615 avc_release_lock(ratelimit_lock); 616 if (lost) { 617 avc_log(SELINUX_WARNING, 618 "%s: %d messages suppressed.\n", avc_prefix, 619 lost); 620 } 621 rc = 1; 622 goto out; 623 } 624 missed++; 625 avc_release_lock(ratelimit_lock); 626 out: 627 avc_free_lock(ratelimit_lock); 628 return rc; 629 } 630 631 static inline int check_avc_ratelimit(void) 632 { 633 if (avc_enforcing) 634 return avc_ratelimit(); 635 else { 636 /* If permissive, then never suppress messages. */ 637 return 1; 638 } 639 } 640 #endif /* ratelimit stuff */ 641 642 /** 643 * avc_dump_av - Display an access vector in human-readable form. 644 * @tclass: target security class 645 * @av: access vector 646 */ 647 static void avc_dump_av(security_class_t tclass, access_vector_t av) 648 { 649 const char *permstr; 650 access_vector_t bit = 1; 651 652 if (av == 0) { 653 log_append(avc_audit_buf, " null"); 654 return; 655 } 656 657 log_append(avc_audit_buf, " {"); 658 659 while (av) { 660 if (av & bit) { 661 permstr = security_av_perm_to_string(tclass, bit); 662 if (!permstr) 663 break; 664 log_append(avc_audit_buf, " %s", permstr); 665 av &= ~bit; 666 } 667 bit <<= 1; 668 } 669 670 if (av) 671 log_append(avc_audit_buf, " 0x%x", av); 672 log_append(avc_audit_buf, " }"); 673 } 674 675 /** 676 * avc_dump_query - Display a SID pair and a class in human-readable form. 677 * @ssid: source security identifier 678 * @tsid: target security identifier 679 * @tclass: target security class 680 */ 681 static void avc_dump_query(security_id_t ssid, security_id_t tsid, 682 security_class_t tclass) 683 { 684 avc_get_lock(avc_lock); 685 686 log_append(avc_audit_buf, "scontext=%s tcontext=%s", 687 ssid->ctx, tsid->ctx); 688 689 avc_release_lock(avc_lock); 690 log_append(avc_audit_buf, " tclass=%s", 691 security_class_to_string(tclass)); 692 } 693 694 void avc_audit(security_id_t ssid, security_id_t tsid, 695 security_class_t tclass, access_vector_t requested, 696 struct av_decision *avd, int result, void *a) 697 { 698 access_vector_t denied, audited; 699 700 denied = requested & ~avd->allowed; 701 if (denied) 702 audited = denied & avd->auditdeny; 703 else if (!requested || result) 704 audited = denied = requested; 705 else 706 audited = requested & avd->auditallow; 707 if (!audited) 708 return; 709 #if 0 710 if (!check_avc_ratelimit()) 711 return; 712 #endif 713 /* prevent overlapping buffer writes */ 714 avc_get_lock(avc_log_lock); 715 snprintf(avc_audit_buf, AVC_AUDIT_BUFSIZE, 716 "%s: %s ", avc_prefix, (denied || !requested) ? "denied" : "granted"); 717 avc_dump_av(tclass, audited); 718 log_append(avc_audit_buf, " for "); 719 720 /* get any extra information printed by the callback */ 721 avc_suppl_audit(a, tclass, avc_audit_buf + strlen(avc_audit_buf), 722 AVC_AUDIT_BUFSIZE - strlen(avc_audit_buf)); 723 724 log_append(avc_audit_buf, " "); 725 avc_dump_query(ssid, tsid, tclass); 726 log_append(avc_audit_buf, "\n"); 727 avc_log(SELINUX_AVC, "%s", avc_audit_buf); 728 729 avc_release_lock(avc_log_lock); 730 } 731 732 hidden_def(avc_audit) 733 734 735 static void avd_init(struct av_decision *avd) 736 { 737 avd->allowed = 0; 738 avd->auditallow = 0; 739 avd->auditdeny = 0xffffffff; 740 avd->seqno = avc_cache.latest_notif; 741 avd->flags = 0; 742 } 743 744 int avc_has_perm_noaudit(security_id_t ssid, 745 security_id_t tsid, 746 security_class_t tclass, 747 access_vector_t requested, 748 struct avc_entry_ref *aeref, struct av_decision *avd) 749 { 750 struct avc_entry *ae; 751 int rc = 0; 752 struct avc_entry entry; 753 access_vector_t denied; 754 struct avc_entry_ref ref; 755 756 if (avd) 757 avd_init(avd); 758 759 if (!avc_using_threads && !avc_app_main_loop) { 760 (void)avc_netlink_check_nb(); 761 } 762 763 if (!aeref) { 764 avc_entry_ref_init(&ref); 765 aeref = &ref; 766 } 767 768 avc_get_lock(avc_lock); 769 avc_cache_stats_incr(entry_lookups); 770 ae = aeref->ae; 771 if (ae) { 772 if (ae->ssid == ssid && 773 ae->tsid == tsid && 774 ae->tclass == tclass && 775 ((ae->avd.decided & requested) == requested)) { 776 avc_cache_stats_incr(entry_hits); 777 ae->used = 1; 778 } else { 779 avc_cache_stats_incr(entry_discards); 780 ae = 0; 781 } 782 } 783 784 if (!ae) { 785 avc_cache_stats_incr(entry_misses); 786 rc = avc_lookup(ssid, tsid, tclass, requested, aeref); 787 if (rc) { 788 rc = security_compute_av_flags_raw(ssid->ctx, tsid->ctx, 789 tclass, requested, 790 &entry.avd); 791 if (rc && errno == EINVAL && !avc_enforcing) { 792 rc = errno = 0; 793 goto out; 794 } 795 if (rc) 796 goto out; 797 rc = avc_insert(ssid, tsid, tclass, &entry, aeref); 798 if (rc) 799 goto out; 800 } 801 ae = aeref->ae; 802 } 803 804 if (avd) 805 memcpy(avd, &ae->avd, sizeof(*avd)); 806 807 denied = requested & ~(ae->avd.allowed); 808 809 if (!requested || denied) { 810 if (!avc_enforcing || 811 (ae->avd.flags & SELINUX_AVD_FLAGS_PERMISSIVE)) 812 ae->avd.allowed |= requested; 813 else { 814 errno = EACCES; 815 rc = -1; 816 } 817 } 818 819 out: 820 avc_release_lock(avc_lock); 821 return rc; 822 } 823 824 hidden_def(avc_has_perm_noaudit) 825 826 int avc_has_perm(security_id_t ssid, security_id_t tsid, 827 security_class_t tclass, access_vector_t requested, 828 struct avc_entry_ref *aeref, void *auditdata) 829 { 830 struct av_decision avd; 831 int errsave, rc; 832 833 rc = avc_has_perm_noaudit(ssid, tsid, tclass, requested, aeref, &avd); 834 errsave = errno; 835 avc_audit(ssid, tsid, tclass, requested, &avd, rc, auditdata); 836 errno = errsave; 837 return rc; 838 } 839 840 int avc_compute_create(security_id_t ssid, security_id_t tsid, 841 security_class_t tclass, security_id_t *newsid) 842 { 843 int rc; 844 struct avc_entry_ref aeref; 845 struct avc_entry entry; 846 char * ctx; 847 848 *newsid = NULL; 849 avc_entry_ref_init(&aeref); 850 851 avc_get_lock(avc_lock); 852 853 /* check for a cached entry */ 854 rc = avc_lookup(ssid, tsid, tclass, 0, &aeref); 855 if (rc) { 856 /* need to make a cache entry for this tuple */ 857 rc = security_compute_av_flags_raw(ssid->ctx, tsid->ctx, 858 tclass, 0, &entry.avd); 859 if (rc) 860 goto out; 861 rc = avc_insert(ssid, tsid, tclass, &entry, &aeref); 862 if (rc) 863 goto out; 864 } 865 866 /* check for a saved compute_create value */ 867 if (!aeref.ae->create_sid) { 868 /* need to query the kernel policy */ 869 rc = security_compute_create_raw(ssid->ctx, tsid->ctx, tclass, 870 &ctx); 871 if (rc) 872 goto out; 873 rc = sidtab_context_to_sid(&avc_sidtab, ctx, newsid); 874 freecon(ctx); 875 if (rc) 876 goto out; 877 878 aeref.ae->create_sid = *newsid; 879 } else { 880 /* found saved value */ 881 *newsid = aeref.ae->create_sid; 882 } 883 884 rc = 0; 885 out: 886 avc_release_lock(avc_lock); 887 return rc; 888 } 889 890 int avc_compute_member(security_id_t ssid, security_id_t tsid, 891 security_class_t tclass, security_id_t *newsid) 892 { 893 int rc; 894 char * ctx = NULL; 895 *newsid = NULL; 896 /* avc_init needs to be called before this function */ 897 assert(avc_running); 898 avc_get_lock(avc_lock); 899 900 rc = security_compute_member_raw(ssid->ctx, tsid->ctx, tclass, &ctx); 901 if (rc) 902 goto out; 903 rc = sidtab_context_to_sid(&avc_sidtab, ctx, newsid); 904 freecon(ctx); 905 out: 906 avc_release_lock(avc_lock); 907 return rc; 908 } 909 910 int avc_add_callback(int (*callback) (uint32_t event, security_id_t ssid, 911 security_id_t tsid, 912 security_class_t tclass, 913 access_vector_t perms, 914 access_vector_t * out_retained), 915 uint32_t events, security_id_t ssid, 916 security_id_t tsid, 917 security_class_t tclass, access_vector_t perms) 918 { 919 struct avc_callback_node *c; 920 int rc = 0; 921 922 c = avc_malloc(sizeof(*c)); 923 if (!c) { 924 rc = -1; 925 goto out; 926 } 927 928 c->callback = callback; 929 c->events = events; 930 c->ssid = ssid; 931 c->tsid = tsid; 932 c->tclass = tclass; 933 c->perms = perms; 934 c->next = avc_callbacks; 935 avc_callbacks = c; 936 out: 937 return rc; 938 } 939 940 static inline int avc_sidcmp(security_id_t x, security_id_t y) 941 { 942 return (x == y || x == SECSID_WILD || y == SECSID_WILD); 943 } 944 945 static inline void avc_update_node(uint32_t event, struct avc_node *node, 946 access_vector_t perms) 947 { 948 switch (event) { 949 case AVC_CALLBACK_GRANT: 950 node->ae.avd.allowed |= perms; 951 break; 952 case AVC_CALLBACK_TRY_REVOKE: 953 case AVC_CALLBACK_REVOKE: 954 node->ae.avd.allowed &= ~perms; 955 break; 956 case AVC_CALLBACK_AUDITALLOW_ENABLE: 957 node->ae.avd.auditallow |= perms; 958 break; 959 case AVC_CALLBACK_AUDITALLOW_DISABLE: 960 node->ae.avd.auditallow &= ~perms; 961 break; 962 case AVC_CALLBACK_AUDITDENY_ENABLE: 963 node->ae.avd.auditdeny |= perms; 964 break; 965 case AVC_CALLBACK_AUDITDENY_DISABLE: 966 node->ae.avd.auditdeny &= ~perms; 967 break; 968 } 969 } 970 971 static int avc_update_cache(uint32_t event, security_id_t ssid, 972 security_id_t tsid, security_class_t tclass, 973 access_vector_t perms) 974 { 975 struct avc_node *node; 976 int i; 977 978 avc_get_lock(avc_lock); 979 980 if (ssid == SECSID_WILD || tsid == SECSID_WILD) { 981 /* apply to all matching nodes */ 982 for (i = 0; i < AVC_CACHE_SLOTS; i++) { 983 for (node = avc_cache.slots[i]; node; node = node->next) { 984 if (avc_sidcmp(ssid, node->ae.ssid) && 985 avc_sidcmp(tsid, node->ae.tsid) && 986 tclass == node->ae.tclass) { 987 avc_update_node(event, node, perms); 988 } 989 } 990 } 991 } else { 992 /* apply to one node */ 993 node = avc_search_node(ssid, tsid, tclass, 0); 994 if (node) { 995 avc_update_node(event, node, perms); 996 } 997 } 998 999 avc_release_lock(avc_lock); 1000 1001 return 0; 1002 } 1003 1004 /* avc_control - update cache and call callbacks 1005 * 1006 * This should not be called directly; use the individual event 1007 * functions instead. 1008 */ 1009 static int avc_control(uint32_t event, security_id_t ssid, 1010 security_id_t tsid, security_class_t tclass, 1011 access_vector_t perms, 1012 uint32_t seqno, access_vector_t * out_retained) 1013 { 1014 struct avc_callback_node *c; 1015 access_vector_t tretained = 0, cretained = 0; 1016 int ret, rc = 0, errsave = 0; 1017 errno = 0; 1018 1019 /* 1020 * try_revoke only removes permissions from the cache 1021 * state if they are not retained by the object manager. 1022 * Hence, try_revoke must wait until after the callbacks have 1023 * been invoked to update the cache state. 1024 */ 1025 if (event != AVC_CALLBACK_TRY_REVOKE) 1026 avc_update_cache(event, ssid, tsid, tclass, perms); 1027 1028 for (c = avc_callbacks; c; c = c->next) { 1029 if ((c->events & event) && 1030 avc_sidcmp(c->ssid, ssid) && 1031 avc_sidcmp(c->tsid, tsid) && 1032 c->tclass == tclass && (c->perms & perms)) { 1033 cretained = 0; 1034 ret = c->callback(event, ssid, tsid, tclass, 1035 (c->perms & perms), &cretained); 1036 if (ret && !rc) { 1037 rc = ret; 1038 errsave = errno; 1039 } 1040 if (!ret) 1041 tretained |= cretained; 1042 } 1043 } 1044 1045 if (event == AVC_CALLBACK_TRY_REVOKE) { 1046 /* revoke any unretained permissions */ 1047 perms &= ~tretained; 1048 avc_update_cache(event, ssid, tsid, tclass, perms); 1049 *out_retained = tretained; 1050 } 1051 1052 avc_get_lock(avc_lock); 1053 if (seqno > avc_cache.latest_notif) 1054 avc_cache.latest_notif = seqno; 1055 avc_release_lock(avc_lock); 1056 1057 errno = errsave; 1058 return rc; 1059 } 1060 1061 /** 1062 * avc_ss_grant - Grant previously denied permissions. 1063 * @ssid: source security identifier or %SECSID_WILD 1064 * @tsid: target security identifier or %SECSID_WILD 1065 * @tclass: target security class 1066 * @perms: permissions to grant 1067 * @seqno: policy sequence number 1068 */ 1069 int avc_ss_grant(security_id_t ssid, security_id_t tsid, 1070 security_class_t tclass, access_vector_t perms, 1071 uint32_t seqno) 1072 { 1073 return avc_control(AVC_CALLBACK_GRANT, 1074 ssid, tsid, tclass, perms, seqno, 0); 1075 } 1076 1077 /** 1078 * avc_ss_try_revoke - Try to revoke previously granted permissions. 1079 * @ssid: source security identifier or %SECSID_WILD 1080 * @tsid: target security identifier or %SECSID_WILD 1081 * @tclass: target security class 1082 * @perms: permissions to grant 1083 * @seqno: policy sequence number 1084 * @out_retained: subset of @perms that are retained 1085 * 1086 * Try to revoke previously granted permissions, but 1087 * only if they are not retained as migrated permissions. 1088 * Return the subset of permissions that are retained via @out_retained. 1089 */ 1090 int avc_ss_try_revoke(security_id_t ssid, security_id_t tsid, 1091 security_class_t tclass, 1092 access_vector_t perms, uint32_t seqno, 1093 access_vector_t * out_retained) 1094 { 1095 return avc_control(AVC_CALLBACK_TRY_REVOKE, 1096 ssid, tsid, tclass, perms, seqno, out_retained); 1097 } 1098 1099 /** 1100 * avc_ss_revoke - Revoke previously granted permissions. 1101 * @ssid: source security identifier or %SECSID_WILD 1102 * @tsid: target security identifier or %SECSID_WILD 1103 * @tclass: target security class 1104 * @perms: permissions to grant 1105 * @seqno: policy sequence number 1106 * 1107 * Revoke previously granted permissions, even if 1108 * they are retained as migrated permissions. 1109 */ 1110 int avc_ss_revoke(security_id_t ssid, security_id_t tsid, 1111 security_class_t tclass, access_vector_t perms, 1112 uint32_t seqno) 1113 { 1114 return avc_control(AVC_CALLBACK_REVOKE, 1115 ssid, tsid, tclass, perms, seqno, 0); 1116 } 1117 1118 /** 1119 * avc_ss_reset - Flush the cache and revalidate migrated permissions. 1120 * @seqno: policy sequence number 1121 */ 1122 int avc_ss_reset(uint32_t seqno) 1123 { 1124 int rc; 1125 1126 rc = avc_reset(); 1127 1128 avc_get_lock(avc_lock); 1129 if (seqno > avc_cache.latest_notif) 1130 avc_cache.latest_notif = seqno; 1131 avc_release_lock(avc_lock); 1132 1133 return rc; 1134 } 1135 1136 /** 1137 * avc_ss_set_auditallow - Enable or disable auditing of granted permissions. 1138 * @ssid: source security identifier or %SECSID_WILD 1139 * @tsid: target security identifier or %SECSID_WILD 1140 * @tclass: target security class 1141 * @perms: permissions to grant 1142 * @seqno: policy sequence number 1143 * @enable: enable flag. 1144 */ 1145 int avc_ss_set_auditallow(security_id_t ssid, security_id_t tsid, 1146 security_class_t tclass, access_vector_t perms, 1147 uint32_t seqno, uint32_t enable) 1148 { 1149 if (enable) 1150 return avc_control(AVC_CALLBACK_AUDITALLOW_ENABLE, 1151 ssid, tsid, tclass, perms, seqno, 0); 1152 else 1153 return avc_control(AVC_CALLBACK_AUDITALLOW_DISABLE, 1154 ssid, tsid, tclass, perms, seqno, 0); 1155 } 1156 1157 /** 1158 * avc_ss_set_auditdeny - Enable or disable auditing of denied permissions. 1159 * @ssid: source security identifier or %SECSID_WILD 1160 * @tsid: target security identifier or %SECSID_WILD 1161 * @tclass: target security class 1162 * @perms: permissions to grant 1163 * @seqno: policy sequence number 1164 * @enable: enable flag. 1165 */ 1166 int avc_ss_set_auditdeny(security_id_t ssid, security_id_t tsid, 1167 security_class_t tclass, access_vector_t perms, 1168 uint32_t seqno, uint32_t enable) 1169 { 1170 if (enable) 1171 return avc_control(AVC_CALLBACK_AUDITDENY_ENABLE, 1172 ssid, tsid, tclass, perms, seqno, 0); 1173 else 1174 return avc_control(AVC_CALLBACK_AUDITDENY_DISABLE, 1175 ssid, tsid, tclass, perms, seqno, 0); 1176 } 1177
