1 /* 2 * Implementation of the kernel access vector cache (AVC). 3 * 4 * Authors: Stephen Smalley, <sds@epoch.ncsc.mil> 5 * James Morris <jmorris@redhat.com> 6 * 7 * Update: KaiGai, Kohei <kaigai@ak.jp.nec.com> 8 * Replaced the avc_lock spinlock by RCU. 9 * 10 * Copyright (C) 2003 Red Hat, Inc., James Morris <jmorris@redhat.com> 11 * 12 * This program is free software; you can redistribute it and/or modify 13 * it under the terms of the GNU General Public License version 2, 14 * as published by the Free Software Foundation. 15 */ 16 #include <linux/types.h> 17 #include <linux/stddef.h> 18 #include <linux/kernel.h> 19 #include <linux/slab.h> 20 #include <linux/fs.h> 21 #include <linux/dcache.h> 22 #include <linux/init.h> 23 #include <linux/skbuff.h> 24 #include <linux/percpu.h> 25 #include <net/sock.h> 26 #include <linux/un.h> 27 #include <net/af_unix.h> 28 #include <linux/ip.h> 29 #include <linux/audit.h> 30 #include <linux/ipv6.h> 31 #include <net/ipv6.h> 32 #include "avc.h" 33 #include "avc_ss.h" 34 35 static const struct av_perm_to_string av_perm_to_string[] = { 36 #define S_(c, v, s) { c, v, s }, 37 #include "av_perm_to_string.h" 38 #undef S_ 39 }; 40 41 static const char *class_to_string[] = { 42 #define S_(s) s, 43 #include "class_to_string.h" 44 #undef S_ 45 }; 46 47 #define TB_(s) static const char *s[] = { 48 #define TE_(s) }; 49 #define S_(s) s, 50 #include "common_perm_to_string.h" 51 #undef TB_ 52 #undef TE_ 53 #undef S_ 54 55 static const struct av_inherit av_inherit[] = { 56 #define S_(c, i, b) { c, common_##i##_perm_to_string, b }, 57 #include "av_inherit.h" 58 #undef S_ 59 }; 60 61 const struct selinux_class_perm selinux_class_perm = { 62 av_perm_to_string, 63 ARRAY_SIZE(av_perm_to_string), 64 class_to_string, 65 ARRAY_SIZE(class_to_string), 66 av_inherit, 67 ARRAY_SIZE(av_inherit) 68 }; 69 70 #define AVC_CACHE_SLOTS 512 71 #define AVC_DEF_CACHE_THRESHOLD 512 72 #define AVC_CACHE_RECLAIM 16 73 74 #ifdef CONFIG_SECURITY_SELINUX_AVC_STATS 75 #define avc_cache_stats_incr(field) \ 76 do { \ 77 per_cpu(avc_cache_stats, get_cpu()).field++; \ 78 put_cpu(); \ 79 } while (0) 80 #else 81 #define avc_cache_stats_incr(field) do {} while (0) 82 #endif 83 84 struct avc_entry { 85 u32 ssid; 86 u32 tsid; 87 u16 tclass; 88 struct av_decision avd; 89 atomic_t used; /* used recently */ 90 }; 91 92 struct avc_node { 93 struct avc_entry ae; 94 struct list_head list; 95 struct rcu_head rhead; 96 }; 97 98 struct avc_cache { 99 struct list_head slots[AVC_CACHE_SLOTS]; 100 spinlock_t slots_lock[AVC_CACHE_SLOTS]; /* lock for writes */ 101 atomic_t lru_hint; /* LRU hint for reclaim scan */ 102 atomic_t active_nodes; 103 u32 latest_notif; /* latest revocation notification */ 104 }; 105 106 struct avc_callback_node { 107 int (*callback) (u32 event, u32 ssid, u32 tsid, 108 u16 tclass, u32 perms, 109 u32 *out_retained); 110 u32 events; 111 u32 ssid; 112 u32 tsid; 113 u16 tclass; 114 u32 perms; 115 struct avc_callback_node *next; 116 }; 117 118 /* Exported via selinufs */ 119 unsigned int avc_cache_threshold = AVC_DEF_CACHE_THRESHOLD; 120 121 #ifdef CONFIG_SECURITY_SELINUX_AVC_STATS 122 DEFINE_PER_CPU(struct avc_cache_stats, avc_cache_stats) = { 0 }; 123 #endif 124 125 static struct avc_cache avc_cache; 126 static struct avc_callback_node *avc_callbacks; 127 static struct kmem_cache *avc_node_cachep; 128 129 static inline int avc_hash(u32 ssid, u32 tsid, u16 tclass) 130 { 131 return (ssid ^ (tsid<<2) ^ (tclass<<4)) & (AVC_CACHE_SLOTS - 1); 132 } 133 134 /** 135 * avc_dump_av - Display an access vector in human-readable form. 136 * @tclass: target security class 137 * @av: access vector 138 */ 139 void avc_dump_av(struct audit_buffer *ab, u16 tclass, u32 av) 140 { 141 const char **common_pts = NULL; 142 u32 common_base = 0; 143 int i, i2, perm; 144 145 if (av == 0) { 146 audit_log_format(ab, " null"); 147 return; 148 } 149 150 for (i = 0; i < ARRAY_SIZE(av_inherit); i++) { 151 if (av_inherit[i].tclass == tclass) { 152 common_pts = av_inherit[i].common_pts; 153 common_base = av_inherit[i].common_base; 154 break; 155 } 156 } 157 158 audit_log_format(ab, " {"); 159 i = 0; 160 perm = 1; 161 while (perm < common_base) { 162 if (perm & av) { 163 audit_log_format(ab, " %s", common_pts[i]); 164 av &= ~perm; 165 } 166 i++; 167 perm <<= 1; 168 } 169 170 while (i < sizeof(av) * 8) { 171 if (perm & av) { 172 for (i2 = 0; i2 < ARRAY_SIZE(av_perm_to_string); i2++) { 173 if ((av_perm_to_string[i2].tclass == tclass) && 174 (av_perm_to_string[i2].value == perm)) 175 break; 176 } 177 if (i2 < ARRAY_SIZE(av_perm_to_string)) { 178 audit_log_format(ab, " %s", 179 av_perm_to_string[i2].name); 180 av &= ~perm; 181 } 182 } 183 i++; 184 perm <<= 1; 185 } 186 187 if (av) 188 audit_log_format(ab, " 0x%x", av); 189 190 audit_log_format(ab, " }"); 191 } 192 193 /** 194 * avc_dump_query - Display a SID pair and a class in human-readable form. 195 * @ssid: source security identifier 196 * @tsid: target security identifier 197 * @tclass: target security class 198 */ 199 static void avc_dump_query(struct audit_buffer *ab, u32 ssid, u32 tsid, u16 tclass) 200 { 201 int rc; 202 char *scontext; 203 u32 scontext_len; 204 205 rc = security_sid_to_context(ssid, &scontext, &scontext_len); 206 if (rc) 207 audit_log_format(ab, "ssid=%d", ssid); 208 else { 209 audit_log_format(ab, "scontext=%s", scontext); 210 kfree(scontext); 211 } 212 213 rc = security_sid_to_context(tsid, &scontext, &scontext_len); 214 if (rc) 215 audit_log_format(ab, " tsid=%d", tsid); 216 else { 217 audit_log_format(ab, " tcontext=%s", scontext); 218 kfree(scontext); 219 } 220 221 BUG_ON(tclass >= ARRAY_SIZE(class_to_string) || !class_to_string[tclass]); 222 audit_log_format(ab, " tclass=%s", class_to_string[tclass]); 223 } 224 225 /** 226 * avc_init - Initialize the AVC. 227 * 228 * Initialize the access vector cache. 229 */ 230 void __init avc_init(void) 231 { 232 int i; 233 234 for (i = 0; i < AVC_CACHE_SLOTS; i++) { 235 INIT_LIST_HEAD(&avc_cache.slots[i]); 236 spin_lock_init(&avc_cache.slots_lock[i]); 237 } 238 atomic_set(&avc_cache.active_nodes, 0); 239 atomic_set(&avc_cache.lru_hint, 0); 240 241 avc_node_cachep = kmem_cache_create("avc_node", sizeof(struct avc_node), 242 0, SLAB_PANIC, NULL); 243 244 audit_log(current->audit_context, GFP_KERNEL, AUDIT_KERNEL, "AVC INITIALIZED\n"); 245 } 246 247 int avc_get_hash_stats(char *page) 248 { 249 int i, chain_len, max_chain_len, slots_used; 250 struct avc_node *node; 251 252 rcu_read_lock(); 253 254 slots_used = 0; 255 max_chain_len = 0; 256 for (i = 0; i < AVC_CACHE_SLOTS; i++) { 257 if (!list_empty(&avc_cache.slots[i])) { 258 slots_used++; 259 chain_len = 0; 260 list_for_each_entry_rcu(node, &avc_cache.slots[i], list) 261 chain_len++; 262 if (chain_len > max_chain_len) 263 max_chain_len = chain_len; 264 } 265 } 266 267 rcu_read_unlock(); 268 269 return scnprintf(page, PAGE_SIZE, "entries: %d\nbuckets used: %d/%d\n" 270 "longest chain: %d\n", 271 atomic_read(&avc_cache.active_nodes), 272 slots_used, AVC_CACHE_SLOTS, max_chain_len); 273 } 274 275 static void avc_node_free(struct rcu_head *rhead) 276 { 277 struct avc_node *node = container_of(rhead, struct avc_node, rhead); 278 kmem_cache_free(avc_node_cachep, node); 279 avc_cache_stats_incr(frees); 280 } 281 282 static void avc_node_delete(struct avc_node *node) 283 { 284 list_del_rcu(&node->list); 285 call_rcu(&node->rhead, avc_node_free); 286 atomic_dec(&avc_cache.active_nodes); 287 } 288 289 static void avc_node_kill(struct avc_node *node) 290 { 291 kmem_cache_free(avc_node_cachep, node); 292 avc_cache_stats_incr(frees); 293 atomic_dec(&avc_cache.active_nodes); 294 } 295 296 static void avc_node_replace(struct avc_node *new, struct avc_node *old) 297 { 298 list_replace_rcu(&old->list, &new->list); 299 call_rcu(&old->rhead, avc_node_free); 300 atomic_dec(&avc_cache.active_nodes); 301 } 302 303 static inline int avc_reclaim_node(void) 304 { 305 struct avc_node *node; 306 int hvalue, try, ecx; 307 unsigned long flags; 308 309 for (try = 0, ecx = 0; try < AVC_CACHE_SLOTS; try++) { 310 hvalue = atomic_inc_return(&avc_cache.lru_hint) & (AVC_CACHE_SLOTS - 1); 311 312 if (!spin_trylock_irqsave(&avc_cache.slots_lock[hvalue], flags)) 313 continue; 314 315 rcu_read_lock(); 316 list_for_each_entry(node, &avc_cache.slots[hvalue], list) { 317 if (atomic_dec_and_test(&node->ae.used)) { 318 /* Recently Unused */ 319 avc_node_delete(node); 320 avc_cache_stats_incr(reclaims); 321 ecx++; 322 if (ecx >= AVC_CACHE_RECLAIM) { 323 rcu_read_unlock(); 324 spin_unlock_irqrestore(&avc_cache.slots_lock[hvalue], flags); 325 goto out; 326 } 327 } 328 } 329 rcu_read_unlock(); 330 spin_unlock_irqrestore(&avc_cache.slots_lock[hvalue], flags); 331 } 332 out: 333 return ecx; 334 } 335 336 static struct avc_node *avc_alloc_node(void) 337 { 338 struct avc_node *node; 339 340 node = kmem_cache_zalloc(avc_node_cachep, GFP_ATOMIC); 341 if (!node) 342 goto out; 343 344 INIT_RCU_HEAD(&node->rhead); 345 INIT_LIST_HEAD(&node->list); 346 atomic_set(&node->ae.used, 1); 347 avc_cache_stats_incr(allocations); 348 349 if (atomic_inc_return(&avc_cache.active_nodes) > avc_cache_threshold) 350 avc_reclaim_node(); 351 352 out: 353 return node; 354 } 355 356 static void avc_node_populate(struct avc_node *node, u32 ssid, u32 tsid, u16 tclass, struct avc_entry *ae) 357 { 358 node->ae.ssid = ssid; 359 node->ae.tsid = tsid; 360 node->ae.tclass = tclass; 361 memcpy(&node->ae.avd, &ae->avd, sizeof(node->ae.avd)); 362 } 363 364 static inline struct avc_node *avc_search_node(u32 ssid, u32 tsid, u16 tclass) 365 { 366 struct avc_node *node, *ret = NULL; 367 int hvalue; 368 369 hvalue = avc_hash(ssid, tsid, tclass); 370 list_for_each_entry_rcu(node, &avc_cache.slots[hvalue], list) { 371 if (ssid == node->ae.ssid && 372 tclass == node->ae.tclass && 373 tsid == node->ae.tsid) { 374 ret = node; 375 break; 376 } 377 } 378 379 if (ret == NULL) { 380 /* cache miss */ 381 goto out; 382 } 383 384 /* cache hit */ 385 if (atomic_read(&ret->ae.used) != 1) 386 atomic_set(&ret->ae.used, 1); 387 out: 388 return ret; 389 } 390 391 /** 392 * avc_lookup - Look up an AVC entry. 393 * @ssid: source security identifier 394 * @tsid: target security identifier 395 * @tclass: target security class 396 * @requested: requested permissions, interpreted based on @tclass 397 * 398 * Look up an AVC entry that is valid for the 399 * @requested permissions between the SID pair 400 * (@ssid, @tsid), interpreting the permissions 401 * based on @tclass. If a valid AVC entry exists, 402 * then this function return the avc_node. 403 * Otherwise, this function returns NULL. 404 */ 405 static struct avc_node *avc_lookup(u32 ssid, u32 tsid, u16 tclass, u32 requested) 406 { 407 struct avc_node *node; 408 409 avc_cache_stats_incr(lookups); 410 node = avc_search_node(ssid, tsid, tclass); 411 412 if (node && ((node->ae.avd.decided & requested) == requested)) { 413 avc_cache_stats_incr(hits); 414 goto out; 415 } 416 417 node = NULL; 418 avc_cache_stats_incr(misses); 419 out: 420 return node; 421 } 422 423 static int avc_latest_notif_update(int seqno, int is_insert) 424 { 425 int ret = 0; 426 static DEFINE_SPINLOCK(notif_lock); 427 unsigned long flag; 428 429 spin_lock_irqsave(¬if_lock, flag); 430 if (is_insert) { 431 if (seqno < avc_cache.latest_notif) { 432 printk(KERN_WARNING "SELinux: avc: seqno %d < latest_notif %d\n", 433 seqno, avc_cache.latest_notif); 434 ret = -EAGAIN; 435 } 436 } else { 437 if (seqno > avc_cache.latest_notif) 438 avc_cache.latest_notif = seqno; 439 } 440 spin_unlock_irqrestore(¬if_lock, flag); 441 442 return ret; 443 } 444 445 /** 446 * avc_insert - Insert an AVC entry. 447 * @ssid: source security identifier 448 * @tsid: target security identifier 449 * @tclass: target security class 450 * @ae: AVC entry 451 * 452 * Insert an AVC entry for the SID pair 453 * (@ssid, @tsid) and class @tclass. 454 * The access vectors and the sequence number are 455 * normally provided by the security server in 456 * response to a security_compute_av() call. If the 457 * sequence number @ae->avd.seqno is not less than the latest 458 * revocation notification, then the function copies 459 * the access vectors into a cache entry, returns 460 * avc_node inserted. Otherwise, this function returns NULL. 461 */ 462 static struct avc_node *avc_insert(u32 ssid, u32 tsid, u16 tclass, struct avc_entry *ae) 463 { 464 struct avc_node *pos, *node = NULL; 465 int hvalue; 466 unsigned long flag; 467 468 if (avc_latest_notif_update(ae->avd.seqno, 1)) 469 goto out; 470 471 node = avc_alloc_node(); 472 if (node) { 473 hvalue = avc_hash(ssid, tsid, tclass); 474 avc_node_populate(node, ssid, tsid, tclass, ae); 475 476 spin_lock_irqsave(&avc_cache.slots_lock[hvalue], flag); 477 list_for_each_entry(pos, &avc_cache.slots[hvalue], list) { 478 if (pos->ae.ssid == ssid && 479 pos->ae.tsid == tsid && 480 pos->ae.tclass == tclass) { 481 avc_node_replace(node, pos); 482 goto found; 483 } 484 } 485 list_add_rcu(&node->list, &avc_cache.slots[hvalue]); 486 found: 487 spin_unlock_irqrestore(&avc_cache.slots_lock[hvalue], flag); 488 } 489 out: 490 return node; 491 } 492 493 static inline void avc_print_ipv6_addr(struct audit_buffer *ab, 494 struct in6_addr *addr, __be16 port, 495 char *name1, char *name2) 496 { 497 if (!ipv6_addr_any(addr)) 498 audit_log_format(ab, " %s=" NIP6_FMT, name1, NIP6(*addr)); 499 if (port) 500 audit_log_format(ab, " %s=%d", name2, ntohs(port)); 501 } 502 503 static inline void avc_print_ipv4_addr(struct audit_buffer *ab, __be32 addr, 504 __be16 port, char *name1, char *name2) 505 { 506 if (addr) 507 audit_log_format(ab, " %s=" NIPQUAD_FMT, name1, NIPQUAD(addr)); 508 if (port) 509 audit_log_format(ab, " %s=%d", name2, ntohs(port)); 510 } 511 512 /** 513 * avc_audit - Audit the granting or denial of permissions. 514 * @ssid: source security identifier 515 * @tsid: target security identifier 516 * @tclass: target security class 517 * @requested: requested permissions 518 * @avd: access vector decisions 519 * @result: result from avc_has_perm_noaudit 520 * @a: auxiliary audit data 521 * 522 * Audit the granting or denial of permissions in accordance 523 * with the policy. This function is typically called by 524 * avc_has_perm() after a permission check, but can also be 525 * called directly by callers who use avc_has_perm_noaudit() 526 * in order to separate the permission check from the auditing. 527 * For example, this separation is useful when the permission check must 528 * be performed under a lock, to allow the lock to be released 529 * before calling the auditing code. 530 */ 531 void avc_audit(u32 ssid, u32 tsid, 532 u16 tclass, u32 requested, 533 struct av_decision *avd, int result, struct avc_audit_data *a) 534 { 535 struct task_struct *tsk = current; 536 struct inode *inode = NULL; 537 u32 denied, audited; 538 struct audit_buffer *ab; 539 540 denied = requested & ~avd->allowed; 541 if (denied) { 542 audited = denied; 543 if (!(audited & avd->auditdeny)) 544 return; 545 } else if (result) { 546 audited = denied = requested; 547 } else { 548 audited = requested; 549 if (!(audited & avd->auditallow)) 550 return; 551 } 552 553 ab = audit_log_start(current->audit_context, GFP_ATOMIC, AUDIT_AVC); 554 if (!ab) 555 return; /* audit_panic has been called */ 556 audit_log_format(ab, "avc: %s ", denied ? "denied" : "granted"); 557 avc_dump_av(ab, tclass, audited); 558 audit_log_format(ab, " for "); 559 if (a && a->tsk) 560 tsk = a->tsk; 561 if (tsk && tsk->pid) { 562 audit_log_format(ab, " pid=%d comm=", tsk->pid); 563 audit_log_untrustedstring(ab, tsk->comm); 564 } 565 if (a) { 566 switch (a->type) { 567 case AVC_AUDIT_DATA_IPC: 568 audit_log_format(ab, " key=%d", a->u.ipc_id); 569 break; 570 case AVC_AUDIT_DATA_CAP: 571 audit_log_format(ab, " capability=%d", a->u.cap); 572 break; 573 case AVC_AUDIT_DATA_FS: 574 if (a->u.fs.path.dentry) { 575 struct dentry *dentry = a->u.fs.path.dentry; 576 if (a->u.fs.path.mnt) { 577 audit_log_d_path(ab, "path=", 578 &a->u.fs.path); 579 } else { 580 audit_log_format(ab, " name="); 581 audit_log_untrustedstring(ab, dentry->d_name.name); 582 } 583 inode = dentry->d_inode; 584 } else if (a->u.fs.inode) { 585 struct dentry *dentry; 586 inode = a->u.fs.inode; 587 dentry = d_find_alias(inode); 588 if (dentry) { 589 audit_log_format(ab, " name="); 590 audit_log_untrustedstring(ab, dentry->d_name.name); 591 dput(dentry); 592 } 593 } 594 if (inode) 595 audit_log_format(ab, " dev=%s ino=%lu", 596 inode->i_sb->s_id, 597 inode->i_ino); 598 break; 599 case AVC_AUDIT_DATA_NET: 600 if (a->u.net.sk) { 601 struct sock *sk = a->u.net.sk; 602 struct unix_sock *u; 603 int len = 0; 604 char *p = NULL; 605 606 switch (sk->sk_family) { 607 case AF_INET: { 608 struct inet_sock *inet = inet_sk(sk); 609 610 avc_print_ipv4_addr(ab, inet->rcv_saddr, 611 inet->sport, 612 "laddr", "lport"); 613 avc_print_ipv4_addr(ab, inet->daddr, 614 inet->dport, 615 "faddr", "fport"); 616 break; 617 } 618 case AF_INET6: { 619 struct inet_sock *inet = inet_sk(sk); 620 struct ipv6_pinfo *inet6 = inet6_sk(sk); 621 622 avc_print_ipv6_addr(ab, &inet6->rcv_saddr, 623 inet->sport, 624 "laddr", "lport"); 625 avc_print_ipv6_addr(ab, &inet6->daddr, 626 inet->dport, 627 "faddr", "fport"); 628 break; 629 } 630 case AF_UNIX: 631 u = unix_sk(sk); 632 if (u->dentry) { 633 struct path path = { 634 .dentry = u->dentry, 635 .mnt = u->mnt 636 }; 637 audit_log_d_path(ab, "path=", 638 &path); 639 break; 640 } 641 if (!u->addr) 642 break; 643 len = u->addr->len-sizeof(short); 644 p = &u->addr->name->sun_path[0]; 645 audit_log_format(ab, " path="); 646 if (*p) 647 audit_log_untrustedstring(ab, p); 648 else 649 audit_log_n_hex(ab, p, len); 650 break; 651 } 652 } 653 654 switch (a->u.net.family) { 655 case AF_INET: 656 avc_print_ipv4_addr(ab, a->u.net.v4info.saddr, 657 a->u.net.sport, 658 "saddr", "src"); 659 avc_print_ipv4_addr(ab, a->u.net.v4info.daddr, 660 a->u.net.dport, 661 "daddr", "dest"); 662 break; 663 case AF_INET6: 664 avc_print_ipv6_addr(ab, &a->u.net.v6info.saddr, 665 a->u.net.sport, 666 "saddr", "src"); 667 avc_print_ipv6_addr(ab, &a->u.net.v6info.daddr, 668 a->u.net.dport, 669 "daddr", "dest"); 670 break; 671 } 672 if (a->u.net.netif > 0) { 673 struct net_device *dev; 674 675 /* NOTE: we always use init's namespace */ 676 dev = dev_get_by_index(&init_net, 677 a->u.net.netif); 678 if (dev) { 679 audit_log_format(ab, " netif=%s", 680 dev->name); 681 dev_put(dev); 682 } 683 } 684 break; 685 } 686 } 687 audit_log_format(ab, " "); 688 avc_dump_query(ab, ssid, tsid, tclass); 689 audit_log_end(ab); 690 } 691 692 /** 693 * avc_add_callback - Register a callback for security events. 694 * @callback: callback function 695 * @events: security events 696 * @ssid: source security identifier or %SECSID_WILD 697 * @tsid: target security identifier or %SECSID_WILD 698 * @tclass: target security class 699 * @perms: permissions 700 * 701 * Register a callback function for events in the set @events 702 * related to the SID pair (@ssid, @tsid) and 703 * and the permissions @perms, interpreting 704 * @perms based on @tclass. Returns %0 on success or 705 * -%ENOMEM if insufficient memory exists to add the callback. 706 */ 707 int avc_add_callback(int (*callback)(u32 event, u32 ssid, u32 tsid, 708 u16 tclass, u32 perms, 709 u32 *out_retained), 710 u32 events, u32 ssid, u32 tsid, 711 u16 tclass, u32 perms) 712 { 713 struct avc_callback_node *c; 714 int rc = 0; 715 716 c = kmalloc(sizeof(*c), GFP_ATOMIC); 717 if (!c) { 718 rc = -ENOMEM; 719 goto out; 720 } 721 722 c->callback = callback; 723 c->events = events; 724 c->ssid = ssid; 725 c->tsid = tsid; 726 c->perms = perms; 727 c->next = avc_callbacks; 728 avc_callbacks = c; 729 out: 730 return rc; 731 } 732 733 static inline int avc_sidcmp(u32 x, u32 y) 734 { 735 return (x == y || x == SECSID_WILD || y == SECSID_WILD); 736 } 737 738 /** 739 * avc_update_node Update an AVC entry 740 * @event : Updating event 741 * @perms : Permission mask bits 742 * @ssid,@tsid,@tclass : identifier of an AVC entry 743 * 744 * if a valid AVC entry doesn't exist,this function returns -ENOENT. 745 * if kmalloc() called internal returns NULL, this function returns -ENOMEM. 746 * otherwise, this function update the AVC entry. The original AVC-entry object 747 * will release later by RCU. 748 */ 749 static int avc_update_node(u32 event, u32 perms, u32 ssid, u32 tsid, u16 tclass) 750 { 751 int hvalue, rc = 0; 752 unsigned long flag; 753 struct avc_node *pos, *node, *orig = NULL; 754 755 node = avc_alloc_node(); 756 if (!node) { 757 rc = -ENOMEM; 758 goto out; 759 } 760 761 /* Lock the target slot */ 762 hvalue = avc_hash(ssid, tsid, tclass); 763 spin_lock_irqsave(&avc_cache.slots_lock[hvalue], flag); 764 765 list_for_each_entry(pos, &avc_cache.slots[hvalue], list) { 766 if (ssid == pos->ae.ssid && 767 tsid == pos->ae.tsid && 768 tclass == pos->ae.tclass){ 769 orig = pos; 770 break; 771 } 772 } 773 774 if (!orig) { 775 rc = -ENOENT; 776 avc_node_kill(node); 777 goto out_unlock; 778 } 779 780 /* 781 * Copy and replace original node. 782 */ 783 784 avc_node_populate(node, ssid, tsid, tclass, &orig->ae); 785 786 switch (event) { 787 case AVC_CALLBACK_GRANT: 788 node->ae.avd.allowed |= perms; 789 break; 790 case AVC_CALLBACK_TRY_REVOKE: 791 case AVC_CALLBACK_REVOKE: 792 node->ae.avd.allowed &= ~perms; 793 break; 794 case AVC_CALLBACK_AUDITALLOW_ENABLE: 795 node->ae.avd.auditallow |= perms; 796 break; 797 case AVC_CALLBACK_AUDITALLOW_DISABLE: 798 node->ae.avd.auditallow &= ~perms; 799 break; 800 case AVC_CALLBACK_AUDITDENY_ENABLE: 801 node->ae.avd.auditdeny |= perms; 802 break; 803 case AVC_CALLBACK_AUDITDENY_DISABLE: 804 node->ae.avd.auditdeny &= ~perms; 805 break; 806 } 807 avc_node_replace(node, orig); 808 out_unlock: 809 spin_unlock_irqrestore(&avc_cache.slots_lock[hvalue], flag); 810 out: 811 return rc; 812 } 813 814 /** 815 * avc_ss_reset - Flush the cache and revalidate migrated permissions. 816 * @seqno: policy sequence number 817 */ 818 int avc_ss_reset(u32 seqno) 819 { 820 struct avc_callback_node *c; 821 int i, rc = 0, tmprc; 822 unsigned long flag; 823 struct avc_node *node; 824 825 for (i = 0; i < AVC_CACHE_SLOTS; i++) { 826 spin_lock_irqsave(&avc_cache.slots_lock[i], flag); 827 /* 828 * With preemptable RCU, the outer spinlock does not 829 * prevent RCU grace periods from ending. 830 */ 831 rcu_read_lock(); 832 list_for_each_entry(node, &avc_cache.slots[i], list) 833 avc_node_delete(node); 834 rcu_read_unlock(); 835 spin_unlock_irqrestore(&avc_cache.slots_lock[i], flag); 836 } 837 838 for (c = avc_callbacks; c; c = c->next) { 839 if (c->events & AVC_CALLBACK_RESET) { 840 tmprc = c->callback(AVC_CALLBACK_RESET, 841 0, 0, 0, 0, NULL); 842 /* save the first error encountered for the return 843 value and continue processing the callbacks */ 844 if (!rc) 845 rc = tmprc; 846 } 847 } 848 849 avc_latest_notif_update(seqno, 0); 850 return rc; 851 } 852 853 /** 854 * avc_has_perm_noaudit - Check permissions but perform no auditing. 855 * @ssid: source security identifier 856 * @tsid: target security identifier 857 * @tclass: target security class 858 * @requested: requested permissions, interpreted based on @tclass 859 * @flags: AVC_STRICT or 0 860 * @avd: access vector decisions 861 * 862 * Check the AVC to determine whether the @requested permissions are granted 863 * for the SID pair (@ssid, @tsid), interpreting the permissions 864 * based on @tclass, and call the security server on a cache miss to obtain 865 * a new decision and add it to the cache. Return a copy of the decisions 866 * in @avd. Return %0 if all @requested permissions are granted, 867 * -%EACCES if any permissions are denied, or another -errno upon 868 * other errors. This function is typically called by avc_has_perm(), 869 * but may also be called directly to separate permission checking from 870 * auditing, e.g. in cases where a lock must be held for the check but 871 * should be released for the auditing. 872 */ 873 int avc_has_perm_noaudit(u32 ssid, u32 tsid, 874 u16 tclass, u32 requested, 875 unsigned flags, 876 struct av_decision *avd) 877 { 878 struct avc_node *node; 879 struct avc_entry entry, *p_ae; 880 int rc = 0; 881 u32 denied; 882 883 BUG_ON(!requested); 884 885 rcu_read_lock(); 886 887 node = avc_lookup(ssid, tsid, tclass, requested); 888 if (!node) { 889 rcu_read_unlock(); 890 rc = security_compute_av(ssid, tsid, tclass, requested, &entry.avd); 891 if (rc) 892 goto out; 893 rcu_read_lock(); 894 node = avc_insert(ssid, tsid, tclass, &entry); 895 } 896 897 p_ae = node ? &node->ae : &entry; 898 899 if (avd) 900 memcpy(avd, &p_ae->avd, sizeof(*avd)); 901 902 denied = requested & ~(p_ae->avd.allowed); 903 904 if (denied) { 905 if (flags & AVC_STRICT) 906 rc = -EACCES; 907 else if (!selinux_enforcing || security_permissive_sid(ssid)) 908 avc_update_node(AVC_CALLBACK_GRANT, requested, ssid, 909 tsid, tclass); 910 else 911 rc = -EACCES; 912 } 913 914 rcu_read_unlock(); 915 out: 916 return rc; 917 } 918 919 /** 920 * avc_has_perm - Check permissions and perform any appropriate auditing. 921 * @ssid: source security identifier 922 * @tsid: target security identifier 923 * @tclass: target security class 924 * @requested: requested permissions, interpreted based on @tclass 925 * @auditdata: auxiliary audit data 926 * 927 * Check the AVC to determine whether the @requested permissions are granted 928 * for the SID pair (@ssid, @tsid), interpreting the permissions 929 * based on @tclass, and call the security server on a cache miss to obtain 930 * a new decision and add it to the cache. Audit the granting or denial of 931 * permissions in accordance with the policy. Return %0 if all @requested 932 * permissions are granted, -%EACCES if any permissions are denied, or 933 * another -errno upon other errors. 934 */ 935 int avc_has_perm(u32 ssid, u32 tsid, u16 tclass, 936 u32 requested, struct avc_audit_data *auditdata) 937 { 938 struct av_decision avd; 939 int rc; 940 941 rc = avc_has_perm_noaudit(ssid, tsid, tclass, requested, 0, &avd); 942 avc_audit(ssid, tsid, tclass, requested, &avd, rc, auditdata); 943 return rc; 944 } 945 946 u32 avc_policy_seqno(void) 947 { 948 return avc_cache.latest_notif; 949 } 950