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) { .tclass = c,\ 57 .common_pts = common_##i##_perm_to_string,\ 58 .common_base = b }, 59 #include "av_inherit.h" 60 #undef S_ 61 }; 62 63 const struct selinux_class_perm selinux_class_perm = { 64 .av_perm_to_string = av_perm_to_string, 65 .av_pts_len = ARRAY_SIZE(av_perm_to_string), 66 .class_to_string = class_to_string, 67 .cts_len = ARRAY_SIZE(class_to_string), 68 .av_inherit = av_inherit, 69 .av_inherit_len = ARRAY_SIZE(av_inherit) 70 }; 71 72 #define AVC_CACHE_SLOTS 512 73 #define AVC_DEF_CACHE_THRESHOLD 512 74 #define AVC_CACHE_RECLAIM 16 75 76 #ifdef CONFIG_SECURITY_SELINUX_AVC_STATS 77 #define avc_cache_stats_incr(field) \ 78 do { \ 79 per_cpu(avc_cache_stats, get_cpu()).field++; \ 80 put_cpu(); \ 81 } while (0) 82 #else 83 #define avc_cache_stats_incr(field) do {} while (0) 84 #endif 85 86 struct avc_entry { 87 u32 ssid; 88 u32 tsid; 89 u16 tclass; 90 struct av_decision avd; 91 atomic_t used; /* used recently */ 92 }; 93 94 struct avc_node { 95 struct avc_entry ae; 96 struct list_head list; 97 struct rcu_head rhead; 98 }; 99 100 struct avc_cache { 101 struct list_head slots[AVC_CACHE_SLOTS]; 102 spinlock_t slots_lock[AVC_CACHE_SLOTS]; /* lock for writes */ 103 atomic_t lru_hint; /* LRU hint for reclaim scan */ 104 atomic_t active_nodes; 105 u32 latest_notif; /* latest revocation notification */ 106 }; 107 108 struct avc_callback_node { 109 int (*callback) (u32 event, u32 ssid, u32 tsid, 110 u16 tclass, u32 perms, 111 u32 *out_retained); 112 u32 events; 113 u32 ssid; 114 u32 tsid; 115 u16 tclass; 116 u32 perms; 117 struct avc_callback_node *next; 118 }; 119 120 /* Exported via selinufs */ 121 unsigned int avc_cache_threshold = AVC_DEF_CACHE_THRESHOLD; 122 123 #ifdef CONFIG_SECURITY_SELINUX_AVC_STATS 124 DEFINE_PER_CPU(struct avc_cache_stats, avc_cache_stats) = { 0 }; 125 #endif 126 127 static struct avc_cache avc_cache; 128 static struct avc_callback_node *avc_callbacks; 129 static struct kmem_cache *avc_node_cachep; 130 131 static inline int avc_hash(u32 ssid, u32 tsid, u16 tclass) 132 { 133 return (ssid ^ (tsid<<2) ^ (tclass<<4)) & (AVC_CACHE_SLOTS - 1); 134 } 135 136 /** 137 * avc_dump_av - Display an access vector in human-readable form. 138 * @tclass: target security class 139 * @av: access vector 140 */ 141 void avc_dump_av(struct audit_buffer *ab, u16 tclass, u32 av) 142 { 143 const char **common_pts = NULL; 144 u32 common_base = 0; 145 int i, i2, perm; 146 147 if (av == 0) { 148 audit_log_format(ab, " null"); 149 return; 150 } 151 152 for (i = 0; i < ARRAY_SIZE(av_inherit); i++) { 153 if (av_inherit[i].tclass == tclass) { 154 common_pts = av_inherit[i].common_pts; 155 common_base = av_inherit[i].common_base; 156 break; 157 } 158 } 159 160 audit_log_format(ab, " {"); 161 i = 0; 162 perm = 1; 163 while (perm < common_base) { 164 if (perm & av) { 165 audit_log_format(ab, " %s", common_pts[i]); 166 av &= ~perm; 167 } 168 i++; 169 perm <<= 1; 170 } 171 172 while (i < sizeof(av) * 8) { 173 if (perm & av) { 174 for (i2 = 0; i2 < ARRAY_SIZE(av_perm_to_string); i2++) { 175 if ((av_perm_to_string[i2].tclass == tclass) && 176 (av_perm_to_string[i2].value == perm)) 177 break; 178 } 179 if (i2 < ARRAY_SIZE(av_perm_to_string)) { 180 audit_log_format(ab, " %s", 181 av_perm_to_string[i2].name); 182 av &= ~perm; 183 } 184 } 185 i++; 186 perm <<= 1; 187 } 188 189 if (av) 190 audit_log_format(ab, " 0x%x", av); 191 192 audit_log_format(ab, " }"); 193 } 194 195 /** 196 * avc_dump_query - Display a SID pair and a class in human-readable form. 197 * @ssid: source security identifier 198 * @tsid: target security identifier 199 * @tclass: target security class 200 */ 201 static void avc_dump_query(struct audit_buffer *ab, u32 ssid, u32 tsid, u16 tclass) 202 { 203 int rc; 204 char *scontext; 205 u32 scontext_len; 206 207 rc = security_sid_to_context(ssid, &scontext, &scontext_len); 208 if (rc) 209 audit_log_format(ab, "ssid=%d", ssid); 210 else { 211 audit_log_format(ab, "scontext=%s", scontext); 212 kfree(scontext); 213 } 214 215 rc = security_sid_to_context(tsid, &scontext, &scontext_len); 216 if (rc) 217 audit_log_format(ab, " tsid=%d", tsid); 218 else { 219 audit_log_format(ab, " tcontext=%s", scontext); 220 kfree(scontext); 221 } 222 223 BUG_ON(tclass >= ARRAY_SIZE(class_to_string) || !class_to_string[tclass]); 224 audit_log_format(ab, " tclass=%s", class_to_string[tclass]); 225 } 226 227 /** 228 * avc_init - Initialize the AVC. 229 * 230 * Initialize the access vector cache. 231 */ 232 void __init avc_init(void) 233 { 234 int i; 235 236 for (i = 0; i < AVC_CACHE_SLOTS; i++) { 237 INIT_LIST_HEAD(&avc_cache.slots[i]); 238 spin_lock_init(&avc_cache.slots_lock[i]); 239 } 240 atomic_set(&avc_cache.active_nodes, 0); 241 atomic_set(&avc_cache.lru_hint, 0); 242 243 avc_node_cachep = kmem_cache_create("avc_node", sizeof(struct avc_node), 244 0, SLAB_PANIC, NULL); 245 246 audit_log(current->audit_context, GFP_KERNEL, AUDIT_KERNEL, "AVC INITIALIZED\n"); 247 } 248 249 int avc_get_hash_stats(char *page) 250 { 251 int i, chain_len, max_chain_len, slots_used; 252 struct avc_node *node; 253 254 rcu_read_lock(); 255 256 slots_used = 0; 257 max_chain_len = 0; 258 for (i = 0; i < AVC_CACHE_SLOTS; i++) { 259 if (!list_empty(&avc_cache.slots[i])) { 260 slots_used++; 261 chain_len = 0; 262 list_for_each_entry_rcu(node, &avc_cache.slots[i], list) 263 chain_len++; 264 if (chain_len > max_chain_len) 265 max_chain_len = chain_len; 266 } 267 } 268 269 rcu_read_unlock(); 270 271 return scnprintf(page, PAGE_SIZE, "entries: %d\nbuckets used: %d/%d\n" 272 "longest chain: %d\n", 273 atomic_read(&avc_cache.active_nodes), 274 slots_used, AVC_CACHE_SLOTS, max_chain_len); 275 } 276 277 static void avc_node_free(struct rcu_head *rhead) 278 { 279 struct avc_node *node = container_of(rhead, struct avc_node, rhead); 280 kmem_cache_free(avc_node_cachep, node); 281 avc_cache_stats_incr(frees); 282 } 283 284 static void avc_node_delete(struct avc_node *node) 285 { 286 list_del_rcu(&node->list); 287 call_rcu(&node->rhead, avc_node_free); 288 atomic_dec(&avc_cache.active_nodes); 289 } 290 291 static void avc_node_kill(struct avc_node *node) 292 { 293 kmem_cache_free(avc_node_cachep, node); 294 avc_cache_stats_incr(frees); 295 atomic_dec(&avc_cache.active_nodes); 296 } 297 298 static void avc_node_replace(struct avc_node *new, struct avc_node *old) 299 { 300 list_replace_rcu(&old->list, &new->list); 301 call_rcu(&old->rhead, avc_node_free); 302 atomic_dec(&avc_cache.active_nodes); 303 } 304 305 static inline int avc_reclaim_node(void) 306 { 307 struct avc_node *node; 308 int hvalue, try, ecx; 309 unsigned long flags; 310 311 for (try = 0, ecx = 0; try < AVC_CACHE_SLOTS; try++) { 312 hvalue = atomic_inc_return(&avc_cache.lru_hint) & (AVC_CACHE_SLOTS - 1); 313 314 if (!spin_trylock_irqsave(&avc_cache.slots_lock[hvalue], flags)) 315 continue; 316 317 rcu_read_lock(); 318 list_for_each_entry(node, &avc_cache.slots[hvalue], list) { 319 if (atomic_dec_and_test(&node->ae.used)) { 320 /* Recently Unused */ 321 avc_node_delete(node); 322 avc_cache_stats_incr(reclaims); 323 ecx++; 324 if (ecx >= AVC_CACHE_RECLAIM) { 325 rcu_read_unlock(); 326 spin_unlock_irqrestore(&avc_cache.slots_lock[hvalue], flags); 327 goto out; 328 } 329 } 330 } 331 rcu_read_unlock(); 332 spin_unlock_irqrestore(&avc_cache.slots_lock[hvalue], flags); 333 } 334 out: 335 return ecx; 336 } 337 338 static struct avc_node *avc_alloc_node(void) 339 { 340 struct avc_node *node; 341 342 node = kmem_cache_zalloc(avc_node_cachep, GFP_ATOMIC); 343 if (!node) 344 goto out; 345 346 INIT_RCU_HEAD(&node->rhead); 347 INIT_LIST_HEAD(&node->list); 348 atomic_set(&node->ae.used, 1); 349 avc_cache_stats_incr(allocations); 350 351 if (atomic_inc_return(&avc_cache.active_nodes) > avc_cache_threshold) 352 avc_reclaim_node(); 353 354 out: 355 return node; 356 } 357 358 static void avc_node_populate(struct avc_node *node, u32 ssid, u32 tsid, u16 tclass, struct avc_entry *ae) 359 { 360 node->ae.ssid = ssid; 361 node->ae.tsid = tsid; 362 node->ae.tclass = tclass; 363 memcpy(&node->ae.avd, &ae->avd, sizeof(node->ae.avd)); 364 } 365 366 static inline struct avc_node *avc_search_node(u32 ssid, u32 tsid, u16 tclass) 367 { 368 struct avc_node *node, *ret = NULL; 369 int hvalue; 370 371 hvalue = avc_hash(ssid, tsid, tclass); 372 list_for_each_entry_rcu(node, &avc_cache.slots[hvalue], list) { 373 if (ssid == node->ae.ssid && 374 tclass == node->ae.tclass && 375 tsid == node->ae.tsid) { 376 ret = node; 377 break; 378 } 379 } 380 381 if (ret == NULL) { 382 /* cache miss */ 383 goto out; 384 } 385 386 /* cache hit */ 387 if (atomic_read(&ret->ae.used) != 1) 388 atomic_set(&ret->ae.used, 1); 389 out: 390 return ret; 391 } 392 393 /** 394 * avc_lookup - Look up an AVC entry. 395 * @ssid: source security identifier 396 * @tsid: target security identifier 397 * @tclass: target security class 398 * @requested: requested permissions, interpreted based on @tclass 399 * 400 * Look up an AVC entry that is valid for the 401 * @requested permissions between the SID pair 402 * (@ssid, @tsid), interpreting the permissions 403 * based on @tclass. If a valid AVC entry exists, 404 * then this function return the avc_node. 405 * Otherwise, this function returns NULL. 406 */ 407 static struct avc_node *avc_lookup(u32 ssid, u32 tsid, u16 tclass, u32 requested) 408 { 409 struct avc_node *node; 410 411 avc_cache_stats_incr(lookups); 412 node = avc_search_node(ssid, tsid, tclass); 413 414 if (node && ((node->ae.avd.decided & requested) == requested)) { 415 avc_cache_stats_incr(hits); 416 goto out; 417 } 418 419 node = NULL; 420 avc_cache_stats_incr(misses); 421 out: 422 return node; 423 } 424 425 static int avc_latest_notif_update(int seqno, int is_insert) 426 { 427 int ret = 0; 428 static DEFINE_SPINLOCK(notif_lock); 429 unsigned long flag; 430 431 spin_lock_irqsave(¬if_lock, flag); 432 if (is_insert) { 433 if (seqno < avc_cache.latest_notif) { 434 printk(KERN_WARNING "SELinux: avc: seqno %d < latest_notif %d\n", 435 seqno, avc_cache.latest_notif); 436 ret = -EAGAIN; 437 } 438 } else { 439 if (seqno > avc_cache.latest_notif) 440 avc_cache.latest_notif = seqno; 441 } 442 spin_unlock_irqrestore(¬if_lock, flag); 443 444 return ret; 445 } 446 447 /** 448 * avc_insert - Insert an AVC entry. 449 * @ssid: source security identifier 450 * @tsid: target security identifier 451 * @tclass: target security class 452 * @ae: AVC entry 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, returns 462 * avc_node inserted. Otherwise, this function returns NULL. 463 */ 464 static struct avc_node *avc_insert(u32 ssid, u32 tsid, u16 tclass, struct avc_entry *ae) 465 { 466 struct avc_node *pos, *node = NULL; 467 int hvalue; 468 unsigned long flag; 469 470 if (avc_latest_notif_update(ae->avd.seqno, 1)) 471 goto out; 472 473 node = avc_alloc_node(); 474 if (node) { 475 hvalue = avc_hash(ssid, tsid, tclass); 476 avc_node_populate(node, ssid, tsid, tclass, ae); 477 478 spin_lock_irqsave(&avc_cache.slots_lock[hvalue], flag); 479 list_for_each_entry(pos, &avc_cache.slots[hvalue], list) { 480 if (pos->ae.ssid == ssid && 481 pos->ae.tsid == tsid && 482 pos->ae.tclass == tclass) { 483 avc_node_replace(node, pos); 484 goto found; 485 } 486 } 487 list_add_rcu(&node->list, &avc_cache.slots[hvalue]); 488 found: 489 spin_unlock_irqrestore(&avc_cache.slots_lock[hvalue], flag); 490 } 491 out: 492 return node; 493 } 494 495 static inline void avc_print_ipv6_addr(struct audit_buffer *ab, 496 struct in6_addr *addr, __be16 port, 497 char *name1, char *name2) 498 { 499 if (!ipv6_addr_any(addr)) 500 audit_log_format(ab, " %s=%pI6", name1, addr); 501 if (port) 502 audit_log_format(ab, " %s=%d", name2, ntohs(port)); 503 } 504 505 static inline void avc_print_ipv4_addr(struct audit_buffer *ab, __be32 addr, 506 __be16 port, char *name1, char *name2) 507 { 508 if (addr) 509 audit_log_format(ab, " %s=%pI4", name1, &addr); 510 if (port) 511 audit_log_format(ab, " %s=%d", name2, ntohs(port)); 512 } 513 514 /** 515 * avc_audit - Audit the granting or denial of permissions. 516 * @ssid: source security identifier 517 * @tsid: target security identifier 518 * @tclass: target security class 519 * @requested: requested permissions 520 * @avd: access vector decisions 521 * @result: result from avc_has_perm_noaudit 522 * @a: auxiliary audit data 523 * 524 * Audit the granting or denial of permissions in accordance 525 * with the policy. This function is typically called by 526 * avc_has_perm() after a permission check, but can also be 527 * called directly by callers who use avc_has_perm_noaudit() 528 * in order to separate the permission check from the auditing. 529 * For example, this separation is useful when the permission check must 530 * be performed under a lock, to allow the lock to be released 531 * before calling the auditing code. 532 */ 533 void avc_audit(u32 ssid, u32 tsid, 534 u16 tclass, u32 requested, 535 struct av_decision *avd, int result, struct avc_audit_data *a) 536 { 537 struct task_struct *tsk = current; 538 struct inode *inode = NULL; 539 u32 denied, audited; 540 struct audit_buffer *ab; 541 542 denied = requested & ~avd->allowed; 543 if (denied) { 544 audited = denied; 545 if (!(audited & avd->auditdeny)) 546 return; 547 } else if (result) { 548 audited = denied = requested; 549 } else { 550 audited = requested; 551 if (!(audited & avd->auditallow)) 552 return; 553 } 554 555 ab = audit_log_start(current->audit_context, GFP_ATOMIC, AUDIT_AVC); 556 if (!ab) 557 return; /* audit_panic has been called */ 558 audit_log_format(ab, "avc: %s ", denied ? "denied" : "granted"); 559 avc_dump_av(ab, tclass, audited); 560 audit_log_format(ab, " for "); 561 if (a && a->tsk) 562 tsk = a->tsk; 563 if (tsk && tsk->pid) { 564 audit_log_format(ab, " pid=%d comm=", tsk->pid); 565 audit_log_untrustedstring(ab, tsk->comm); 566 } 567 if (a) { 568 switch (a->type) { 569 case AVC_AUDIT_DATA_IPC: 570 audit_log_format(ab, " key=%d", a->u.ipc_id); 571 break; 572 case AVC_AUDIT_DATA_CAP: 573 audit_log_format(ab, " capability=%d", a->u.cap); 574 break; 575 case AVC_AUDIT_DATA_FS: 576 if (a->u.fs.path.dentry) { 577 struct dentry *dentry = a->u.fs.path.dentry; 578 if (a->u.fs.path.mnt) { 579 audit_log_d_path(ab, "path=", 580 &a->u.fs.path); 581 } else { 582 audit_log_format(ab, " name="); 583 audit_log_untrustedstring(ab, dentry->d_name.name); 584 } 585 inode = dentry->d_inode; 586 } else if (a->u.fs.inode) { 587 struct dentry *dentry; 588 inode = a->u.fs.inode; 589 dentry = d_find_alias(inode); 590 if (dentry) { 591 audit_log_format(ab, " name="); 592 audit_log_untrustedstring(ab, dentry->d_name.name); 593 dput(dentry); 594 } 595 } 596 if (inode) 597 audit_log_format(ab, " dev=%s ino=%lu", 598 inode->i_sb->s_id, 599 inode->i_ino); 600 break; 601 case AVC_AUDIT_DATA_NET: 602 if (a->u.net.sk) { 603 struct sock *sk = a->u.net.sk; 604 struct unix_sock *u; 605 int len = 0; 606 char *p = NULL; 607 608 switch (sk->sk_family) { 609 case AF_INET: { 610 struct inet_sock *inet = inet_sk(sk); 611 612 avc_print_ipv4_addr(ab, inet->rcv_saddr, 613 inet->sport, 614 "laddr", "lport"); 615 avc_print_ipv4_addr(ab, inet->daddr, 616 inet->dport, 617 "faddr", "fport"); 618 break; 619 } 620 case AF_INET6: { 621 struct inet_sock *inet = inet_sk(sk); 622 struct ipv6_pinfo *inet6 = inet6_sk(sk); 623 624 avc_print_ipv6_addr(ab, &inet6->rcv_saddr, 625 inet->sport, 626 "laddr", "lport"); 627 avc_print_ipv6_addr(ab, &inet6->daddr, 628 inet->dport, 629 "faddr", "fport"); 630 break; 631 } 632 case AF_UNIX: 633 u = unix_sk(sk); 634 if (u->dentry) { 635 struct path path = { 636 .dentry = u->dentry, 637 .mnt = u->mnt 638 }; 639 audit_log_d_path(ab, "path=", 640 &path); 641 break; 642 } 643 if (!u->addr) 644 break; 645 len = u->addr->len-sizeof(short); 646 p = &u->addr->name->sun_path[0]; 647 audit_log_format(ab, " path="); 648 if (*p) 649 audit_log_untrustedstring(ab, p); 650 else 651 audit_log_n_hex(ab, p, len); 652 break; 653 } 654 } 655 656 switch (a->u.net.family) { 657 case AF_INET: 658 avc_print_ipv4_addr(ab, a->u.net.v4info.saddr, 659 a->u.net.sport, 660 "saddr", "src"); 661 avc_print_ipv4_addr(ab, a->u.net.v4info.daddr, 662 a->u.net.dport, 663 "daddr", "dest"); 664 break; 665 case AF_INET6: 666 avc_print_ipv6_addr(ab, &a->u.net.v6info.saddr, 667 a->u.net.sport, 668 "saddr", "src"); 669 avc_print_ipv6_addr(ab, &a->u.net.v6info.daddr, 670 a->u.net.dport, 671 "daddr", "dest"); 672 break; 673 } 674 if (a->u.net.netif > 0) { 675 struct net_device *dev; 676 677 /* NOTE: we always use init's namespace */ 678 dev = dev_get_by_index(&init_net, 679 a->u.net.netif); 680 if (dev) { 681 audit_log_format(ab, " netif=%s", 682 dev->name); 683 dev_put(dev); 684 } 685 } 686 break; 687 } 688 } 689 audit_log_format(ab, " "); 690 avc_dump_query(ab, ssid, tsid, tclass); 691 audit_log_end(ab); 692 } 693 694 /** 695 * avc_add_callback - Register a callback for security events. 696 * @callback: callback function 697 * @events: security events 698 * @ssid: source security identifier or %SECSID_WILD 699 * @tsid: target security identifier or %SECSID_WILD 700 * @tclass: target security class 701 * @perms: permissions 702 * 703 * Register a callback function for events in the set @events 704 * related to the SID pair (@ssid, @tsid) and 705 * and the permissions @perms, interpreting 706 * @perms based on @tclass. Returns %0 on success or 707 * -%ENOMEM if insufficient memory exists to add the callback. 708 */ 709 int avc_add_callback(int (*callback)(u32 event, u32 ssid, u32 tsid, 710 u16 tclass, u32 perms, 711 u32 *out_retained), 712 u32 events, u32 ssid, u32 tsid, 713 u16 tclass, u32 perms) 714 { 715 struct avc_callback_node *c; 716 int rc = 0; 717 718 c = kmalloc(sizeof(*c), GFP_ATOMIC); 719 if (!c) { 720 rc = -ENOMEM; 721 goto out; 722 } 723 724 c->callback = callback; 725 c->events = events; 726 c->ssid = ssid; 727 c->tsid = tsid; 728 c->perms = perms; 729 c->next = avc_callbacks; 730 avc_callbacks = c; 731 out: 732 return rc; 733 } 734 735 static inline int avc_sidcmp(u32 x, u32 y) 736 { 737 return (x == y || x == SECSID_WILD || y == SECSID_WILD); 738 } 739 740 /** 741 * avc_update_node Update an AVC entry 742 * @event : Updating event 743 * @perms : Permission mask bits 744 * @ssid,@tsid,@tclass : identifier of an AVC entry 745 * 746 * if a valid AVC entry doesn't exist,this function returns -ENOENT. 747 * if kmalloc() called internal returns NULL, this function returns -ENOMEM. 748 * otherwise, this function update the AVC entry. The original AVC-entry object 749 * will release later by RCU. 750 */ 751 static int avc_update_node(u32 event, u32 perms, u32 ssid, u32 tsid, u16 tclass) 752 { 753 int hvalue, rc = 0; 754 unsigned long flag; 755 struct avc_node *pos, *node, *orig = NULL; 756 757 node = avc_alloc_node(); 758 if (!node) { 759 rc = -ENOMEM; 760 goto out; 761 } 762 763 /* Lock the target slot */ 764 hvalue = avc_hash(ssid, tsid, tclass); 765 spin_lock_irqsave(&avc_cache.slots_lock[hvalue], flag); 766 767 list_for_each_entry(pos, &avc_cache.slots[hvalue], list) { 768 if (ssid == pos->ae.ssid && 769 tsid == pos->ae.tsid && 770 tclass == pos->ae.tclass){ 771 orig = pos; 772 break; 773 } 774 } 775 776 if (!orig) { 777 rc = -ENOENT; 778 avc_node_kill(node); 779 goto out_unlock; 780 } 781 782 /* 783 * Copy and replace original node. 784 */ 785 786 avc_node_populate(node, ssid, tsid, tclass, &orig->ae); 787 788 switch (event) { 789 case AVC_CALLBACK_GRANT: 790 node->ae.avd.allowed |= perms; 791 break; 792 case AVC_CALLBACK_TRY_REVOKE: 793 case AVC_CALLBACK_REVOKE: 794 node->ae.avd.allowed &= ~perms; 795 break; 796 case AVC_CALLBACK_AUDITALLOW_ENABLE: 797 node->ae.avd.auditallow |= perms; 798 break; 799 case AVC_CALLBACK_AUDITALLOW_DISABLE: 800 node->ae.avd.auditallow &= ~perms; 801 break; 802 case AVC_CALLBACK_AUDITDENY_ENABLE: 803 node->ae.avd.auditdeny |= perms; 804 break; 805 case AVC_CALLBACK_AUDITDENY_DISABLE: 806 node->ae.avd.auditdeny &= ~perms; 807 break; 808 } 809 avc_node_replace(node, orig); 810 out_unlock: 811 spin_unlock_irqrestore(&avc_cache.slots_lock[hvalue], flag); 812 out: 813 return rc; 814 } 815 816 /** 817 * avc_ss_reset - Flush the cache and revalidate migrated permissions. 818 * @seqno: policy sequence number 819 */ 820 int avc_ss_reset(u32 seqno) 821 { 822 struct avc_callback_node *c; 823 int i, rc = 0, tmprc; 824 unsigned long flag; 825 struct avc_node *node; 826 827 for (i = 0; i < AVC_CACHE_SLOTS; i++) { 828 spin_lock_irqsave(&avc_cache.slots_lock[i], flag); 829 /* 830 * With preemptable RCU, the outer spinlock does not 831 * prevent RCU grace periods from ending. 832 */ 833 rcu_read_lock(); 834 list_for_each_entry(node, &avc_cache.slots[i], list) 835 avc_node_delete(node); 836 rcu_read_unlock(); 837 spin_unlock_irqrestore(&avc_cache.slots_lock[i], flag); 838 } 839 840 for (c = avc_callbacks; c; c = c->next) { 841 if (c->events & AVC_CALLBACK_RESET) { 842 tmprc = c->callback(AVC_CALLBACK_RESET, 843 0, 0, 0, 0, NULL); 844 /* save the first error encountered for the return 845 value and continue processing the callbacks */ 846 if (!rc) 847 rc = tmprc; 848 } 849 } 850 851 avc_latest_notif_update(seqno, 0); 852 return rc; 853 } 854 855 /** 856 * avc_has_perm_noaudit - Check permissions but perform no auditing. 857 * @ssid: source security identifier 858 * @tsid: target security identifier 859 * @tclass: target security class 860 * @requested: requested permissions, interpreted based on @tclass 861 * @flags: AVC_STRICT or 0 862 * @avd: access vector decisions 863 * 864 * Check the AVC to determine whether the @requested permissions are granted 865 * for the SID pair (@ssid, @tsid), interpreting the permissions 866 * based on @tclass, and call the security server on a cache miss to obtain 867 * a new decision and add it to the cache. Return a copy of the decisions 868 * in @avd. Return %0 if all @requested permissions are granted, 869 * -%EACCES if any permissions are denied, or another -errno upon 870 * other errors. This function is typically called by avc_has_perm(), 871 * but may also be called directly to separate permission checking from 872 * auditing, e.g. in cases where a lock must be held for the check but 873 * should be released for the auditing. 874 */ 875 int avc_has_perm_noaudit(u32 ssid, u32 tsid, 876 u16 tclass, u32 requested, 877 unsigned flags, 878 struct av_decision *avd) 879 { 880 struct avc_node *node; 881 struct avc_entry entry, *p_ae; 882 int rc = 0; 883 u32 denied; 884 885 BUG_ON(!requested); 886 887 rcu_read_lock(); 888 889 node = avc_lookup(ssid, tsid, tclass, requested); 890 if (!node) { 891 rcu_read_unlock(); 892 rc = security_compute_av(ssid, tsid, tclass, requested, &entry.avd); 893 if (rc) 894 goto out; 895 rcu_read_lock(); 896 node = avc_insert(ssid, tsid, tclass, &entry); 897 } 898 899 p_ae = node ? &node->ae : &entry; 900 901 if (avd) 902 memcpy(avd, &p_ae->avd, sizeof(*avd)); 903 904 denied = requested & ~(p_ae->avd.allowed); 905 906 if (denied) { 907 if (flags & AVC_STRICT) 908 rc = -EACCES; 909 else if (!selinux_enforcing || security_permissive_sid(ssid)) 910 avc_update_node(AVC_CALLBACK_GRANT, requested, ssid, 911 tsid, tclass); 912 else 913 rc = -EACCES; 914 } 915 916 rcu_read_unlock(); 917 out: 918 return rc; 919 } 920 921 /** 922 * avc_has_perm - Check permissions and perform any appropriate auditing. 923 * @ssid: source security identifier 924 * @tsid: target security identifier 925 * @tclass: target security class 926 * @requested: requested permissions, interpreted based on @tclass 927 * @auditdata: auxiliary audit data 928 * 929 * Check the AVC to determine whether the @requested permissions are granted 930 * for the SID pair (@ssid, @tsid), interpreting the permissions 931 * based on @tclass, and call the security server on a cache miss to obtain 932 * a new decision and add it to the cache. Audit the granting or denial of 933 * permissions in accordance with the policy. Return %0 if all @requested 934 * permissions are granted, -%EACCES if any permissions are denied, or 935 * another -errno upon other errors. 936 */ 937 int avc_has_perm(u32 ssid, u32 tsid, u16 tclass, 938 u32 requested, struct avc_audit_data *auditdata) 939 { 940 struct av_decision avd; 941 int rc; 942 943 rc = avc_has_perm_noaudit(ssid, tsid, tclass, requested, 0, &avd); 944 avc_audit(ssid, tsid, tclass, requested, &avd, rc, auditdata); 945 return rc; 946 } 947 948 u32 avc_policy_seqno(void) 949 { 950 return avc_cache.latest_notif; 951 } 952