avc.c revision 89c86576ecde504da1eeb4f4882b2189ac2f9c4a
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 35static 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 41static 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 55static 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 63const 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) \ 78do { \ 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 86struct avc_entry { 87 u32 ssid; 88 u32 tsid; 89 u16 tclass; 90 struct av_decision avd; 91}; 92 93struct avc_node { 94 struct avc_entry ae; 95 struct hlist_node list; /* anchored in avc_cache->slots[i] */ 96 struct rcu_head rhead; 97}; 98 99struct avc_cache { 100 struct hlist_head slots[AVC_CACHE_SLOTS]; /* head for avc_node->list */ 101 spinlock_t slots_lock[AVC_CACHE_SLOTS]; /* lock for writes */ 102 atomic_t lru_hint; /* LRU hint for reclaim scan */ 103 atomic_t active_nodes; 104 u32 latest_notif; /* latest revocation notification */ 105}; 106 107struct avc_callback_node { 108 int (*callback) (u32 event, u32 ssid, u32 tsid, 109 u16 tclass, u32 perms, 110 u32 *out_retained); 111 u32 events; 112 u32 ssid; 113 u32 tsid; 114 u16 tclass; 115 u32 perms; 116 struct avc_callback_node *next; 117}; 118 119/* Exported via selinufs */ 120unsigned int avc_cache_threshold = AVC_DEF_CACHE_THRESHOLD; 121 122#ifdef CONFIG_SECURITY_SELINUX_AVC_STATS 123DEFINE_PER_CPU(struct avc_cache_stats, avc_cache_stats) = { 0 }; 124#endif 125 126static struct avc_cache avc_cache; 127static struct avc_callback_node *avc_callbacks; 128static struct kmem_cache *avc_node_cachep; 129 130static inline int avc_hash(u32 ssid, u32 tsid, u16 tclass) 131{ 132 return (ssid ^ (tsid<<2) ^ (tclass<<4)) & (AVC_CACHE_SLOTS - 1); 133} 134 135/** 136 * avc_dump_av - Display an access vector in human-readable form. 137 * @tclass: target security class 138 * @av: access vector 139 */ 140static void avc_dump_av(struct audit_buffer *ab, u16 tclass, u32 av) 141{ 142 const char **common_pts = NULL; 143 u32 common_base = 0; 144 int i, i2, perm; 145 146 if (av == 0) { 147 audit_log_format(ab, " null"); 148 return; 149 } 150 151 for (i = 0; i < ARRAY_SIZE(av_inherit); i++) { 152 if (av_inherit[i].tclass == tclass) { 153 common_pts = av_inherit[i].common_pts; 154 common_base = av_inherit[i].common_base; 155 break; 156 } 157 } 158 159 audit_log_format(ab, " {"); 160 i = 0; 161 perm = 1; 162 while (perm < common_base) { 163 if (perm & av) { 164 audit_log_format(ab, " %s", common_pts[i]); 165 av &= ~perm; 166 } 167 i++; 168 perm <<= 1; 169 } 170 171 while (i < sizeof(av) * 8) { 172 if (perm & av) { 173 for (i2 = 0; i2 < ARRAY_SIZE(av_perm_to_string); i2++) { 174 if ((av_perm_to_string[i2].tclass == tclass) && 175 (av_perm_to_string[i2].value == perm)) 176 break; 177 } 178 if (i2 < ARRAY_SIZE(av_perm_to_string)) { 179 audit_log_format(ab, " %s", 180 av_perm_to_string[i2].name); 181 av &= ~perm; 182 } 183 } 184 i++; 185 perm <<= 1; 186 } 187 188 if (av) 189 audit_log_format(ab, " 0x%x", av); 190 191 audit_log_format(ab, " }"); 192} 193 194/** 195 * avc_dump_query - Display a SID pair and a class in human-readable form. 196 * @ssid: source security identifier 197 * @tsid: target security identifier 198 * @tclass: target security class 199 */ 200static void avc_dump_query(struct audit_buffer *ab, u32 ssid, u32 tsid, u16 tclass) 201{ 202 int rc; 203 char *scontext; 204 u32 scontext_len; 205 206 rc = security_sid_to_context(ssid, &scontext, &scontext_len); 207 if (rc) 208 audit_log_format(ab, "ssid=%d", ssid); 209 else { 210 audit_log_format(ab, "scontext=%s", scontext); 211 kfree(scontext); 212 } 213 214 rc = security_sid_to_context(tsid, &scontext, &scontext_len); 215 if (rc) 216 audit_log_format(ab, " tsid=%d", tsid); 217 else { 218 audit_log_format(ab, " tcontext=%s", scontext); 219 kfree(scontext); 220 } 221 222 BUG_ON(tclass >= ARRAY_SIZE(class_to_string) || !class_to_string[tclass]); 223 audit_log_format(ab, " tclass=%s", class_to_string[tclass]); 224} 225 226/** 227 * avc_init - Initialize the AVC. 228 * 229 * Initialize the access vector cache. 230 */ 231void __init avc_init(void) 232{ 233 int i; 234 235 for (i = 0; i < AVC_CACHE_SLOTS; i++) { 236 INIT_HLIST_HEAD(&avc_cache.slots[i]); 237 spin_lock_init(&avc_cache.slots_lock[i]); 238 } 239 atomic_set(&avc_cache.active_nodes, 0); 240 atomic_set(&avc_cache.lru_hint, 0); 241 242 avc_node_cachep = kmem_cache_create("avc_node", sizeof(struct avc_node), 243 0, SLAB_PANIC, NULL); 244 245 audit_log(current->audit_context, GFP_KERNEL, AUDIT_KERNEL, "AVC INITIALIZED\n"); 246} 247 248int avc_get_hash_stats(char *page) 249{ 250 int i, chain_len, max_chain_len, slots_used; 251 struct avc_node *node; 252 struct hlist_head *head; 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 head = &avc_cache.slots[i]; 260 if (!hlist_empty(head)) { 261 struct hlist_node *next; 262 263 slots_used++; 264 chain_len = 0; 265 hlist_for_each_entry_rcu(node, next, head, list) 266 chain_len++; 267 if (chain_len > max_chain_len) 268 max_chain_len = chain_len; 269 } 270 } 271 272 rcu_read_unlock(); 273 274 return scnprintf(page, PAGE_SIZE, "entries: %d\nbuckets used: %d/%d\n" 275 "longest chain: %d\n", 276 atomic_read(&avc_cache.active_nodes), 277 slots_used, AVC_CACHE_SLOTS, max_chain_len); 278} 279 280static void avc_node_free(struct rcu_head *rhead) 281{ 282 struct avc_node *node = container_of(rhead, struct avc_node, rhead); 283 kmem_cache_free(avc_node_cachep, node); 284 avc_cache_stats_incr(frees); 285} 286 287static void avc_node_delete(struct avc_node *node) 288{ 289 hlist_del_rcu(&node->list); 290 call_rcu(&node->rhead, avc_node_free); 291 atomic_dec(&avc_cache.active_nodes); 292} 293 294static void avc_node_kill(struct avc_node *node) 295{ 296 kmem_cache_free(avc_node_cachep, node); 297 avc_cache_stats_incr(frees); 298 atomic_dec(&avc_cache.active_nodes); 299} 300 301static void avc_node_replace(struct avc_node *new, struct avc_node *old) 302{ 303 hlist_replace_rcu(&old->list, &new->list); 304 call_rcu(&old->rhead, avc_node_free); 305 atomic_dec(&avc_cache.active_nodes); 306} 307 308static inline int avc_reclaim_node(void) 309{ 310 struct avc_node *node; 311 int hvalue, try, ecx; 312 unsigned long flags; 313 struct hlist_head *head; 314 struct hlist_node *next; 315 spinlock_t *lock; 316 317 for (try = 0, ecx = 0; try < AVC_CACHE_SLOTS; try++) { 318 hvalue = atomic_inc_return(&avc_cache.lru_hint) & (AVC_CACHE_SLOTS - 1); 319 head = &avc_cache.slots[hvalue]; 320 lock = &avc_cache.slots_lock[hvalue]; 321 322 if (!spin_trylock_irqsave(lock, flags)) 323 continue; 324 325 rcu_read_lock(); 326 hlist_for_each_entry(node, next, head, list) { 327 avc_node_delete(node); 328 avc_cache_stats_incr(reclaims); 329 ecx++; 330 if (ecx >= AVC_CACHE_RECLAIM) { 331 rcu_read_unlock(); 332 spin_unlock_irqrestore(lock, flags); 333 goto out; 334 } 335 } 336 rcu_read_unlock(); 337 spin_unlock_irqrestore(lock, flags); 338 } 339out: 340 return ecx; 341} 342 343static struct avc_node *avc_alloc_node(void) 344{ 345 struct avc_node *node; 346 347 node = kmem_cache_zalloc(avc_node_cachep, GFP_ATOMIC); 348 if (!node) 349 goto out; 350 351 INIT_RCU_HEAD(&node->rhead); 352 INIT_HLIST_NODE(&node->list); 353 avc_cache_stats_incr(allocations); 354 355 if (atomic_inc_return(&avc_cache.active_nodes) > avc_cache_threshold) 356 avc_reclaim_node(); 357 358out: 359 return node; 360} 361 362static void avc_node_populate(struct avc_node *node, u32 ssid, u32 tsid, u16 tclass, struct av_decision *avd) 363{ 364 node->ae.ssid = ssid; 365 node->ae.tsid = tsid; 366 node->ae.tclass = tclass; 367 memcpy(&node->ae.avd, avd, sizeof(node->ae.avd)); 368} 369 370static inline struct avc_node *avc_search_node(u32 ssid, u32 tsid, u16 tclass) 371{ 372 struct avc_node *node, *ret = NULL; 373 int hvalue; 374 struct hlist_head *head; 375 struct hlist_node *next; 376 377 hvalue = avc_hash(ssid, tsid, tclass); 378 head = &avc_cache.slots[hvalue]; 379 hlist_for_each_entry_rcu(node, next, head, list) { 380 if (ssid == node->ae.ssid && 381 tclass == node->ae.tclass && 382 tsid == node->ae.tsid) { 383 ret = node; 384 break; 385 } 386 } 387 388 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 * 397 * Look up an AVC entry that is valid for the 398 * (@ssid, @tsid), interpreting the permissions 399 * based on @tclass. If a valid AVC entry exists, 400 * then this function return the avc_node. 401 * Otherwise, this function returns NULL. 402 */ 403static struct avc_node *avc_lookup(u32 ssid, u32 tsid, u16 tclass) 404{ 405 struct avc_node *node; 406 407 avc_cache_stats_incr(lookups); 408 node = avc_search_node(ssid, tsid, tclass); 409 410 if (node) 411 avc_cache_stats_incr(hits); 412 else 413 avc_cache_stats_incr(misses); 414 415 return node; 416} 417 418static int avc_latest_notif_update(int seqno, int is_insert) 419{ 420 int ret = 0; 421 static DEFINE_SPINLOCK(notif_lock); 422 unsigned long flag; 423 424 spin_lock_irqsave(¬if_lock, flag); 425 if (is_insert) { 426 if (seqno < avc_cache.latest_notif) { 427 printk(KERN_WARNING "SELinux: avc: seqno %d < latest_notif %d\n", 428 seqno, avc_cache.latest_notif); 429 ret = -EAGAIN; 430 } 431 } else { 432 if (seqno > avc_cache.latest_notif) 433 avc_cache.latest_notif = seqno; 434 } 435 spin_unlock_irqrestore(¬if_lock, flag); 436 437 return ret; 438} 439 440/** 441 * avc_insert - Insert an AVC entry. 442 * @ssid: source security identifier 443 * @tsid: target security identifier 444 * @tclass: target security class 445 * @avd: resulting av decision 446 * 447 * Insert an AVC entry for the SID pair 448 * (@ssid, @tsid) and class @tclass. 449 * The access vectors and the sequence number are 450 * normally provided by the security server in 451 * response to a security_compute_av() call. If the 452 * sequence number @avd->seqno is not less than the latest 453 * revocation notification, then the function copies 454 * the access vectors into a cache entry, returns 455 * avc_node inserted. Otherwise, this function returns NULL. 456 */ 457static struct avc_node *avc_insert(u32 ssid, u32 tsid, u16 tclass, struct av_decision *avd) 458{ 459 struct avc_node *pos, *node = NULL; 460 int hvalue; 461 unsigned long flag; 462 463 if (avc_latest_notif_update(avd->seqno, 1)) 464 goto out; 465 466 node = avc_alloc_node(); 467 if (node) { 468 struct hlist_head *head; 469 struct hlist_node *next; 470 spinlock_t *lock; 471 472 hvalue = avc_hash(ssid, tsid, tclass); 473 avc_node_populate(node, ssid, tsid, tclass, avd); 474 475 head = &avc_cache.slots[hvalue]; 476 lock = &avc_cache.slots_lock[hvalue]; 477 478 spin_lock_irqsave(lock, flag); 479 hlist_for_each_entry(pos, next, head, 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 hlist_add_head_rcu(&node->list, head); 488found: 489 spin_unlock_irqrestore(lock, flag); 490 } 491out: 492 return node; 493} 494 495static 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 505static 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 */ 533void 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 */ 709int 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; 731out: 732 return rc; 733} 734 735static 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 * @seqno : sequence number when decision was made 746 * 747 * if a valid AVC entry doesn't exist,this function returns -ENOENT. 748 * if kmalloc() called internal returns NULL, this function returns -ENOMEM. 749 * otherwise, this function update the AVC entry. The original AVC-entry object 750 * will release later by RCU. 751 */ 752static int avc_update_node(u32 event, u32 perms, u32 ssid, u32 tsid, u16 tclass, 753 u32 seqno) 754{ 755 int hvalue, rc = 0; 756 unsigned long flag; 757 struct avc_node *pos, *node, *orig = NULL; 758 struct hlist_head *head; 759 struct hlist_node *next; 760 spinlock_t *lock; 761 762 node = avc_alloc_node(); 763 if (!node) { 764 rc = -ENOMEM; 765 goto out; 766 } 767 768 /* Lock the target slot */ 769 hvalue = avc_hash(ssid, tsid, tclass); 770 771 head = &avc_cache.slots[hvalue]; 772 lock = &avc_cache.slots_lock[hvalue]; 773 774 spin_lock_irqsave(lock, flag); 775 776 hlist_for_each_entry(pos, next, head, list) { 777 if (ssid == pos->ae.ssid && 778 tsid == pos->ae.tsid && 779 tclass == pos->ae.tclass && 780 seqno == pos->ae.avd.seqno){ 781 orig = pos; 782 break; 783 } 784 } 785 786 if (!orig) { 787 rc = -ENOENT; 788 avc_node_kill(node); 789 goto out_unlock; 790 } 791 792 /* 793 * Copy and replace original node. 794 */ 795 796 avc_node_populate(node, ssid, tsid, tclass, &orig->ae.avd); 797 798 switch (event) { 799 case AVC_CALLBACK_GRANT: 800 node->ae.avd.allowed |= perms; 801 break; 802 case AVC_CALLBACK_TRY_REVOKE: 803 case AVC_CALLBACK_REVOKE: 804 node->ae.avd.allowed &= ~perms; 805 break; 806 case AVC_CALLBACK_AUDITALLOW_ENABLE: 807 node->ae.avd.auditallow |= perms; 808 break; 809 case AVC_CALLBACK_AUDITALLOW_DISABLE: 810 node->ae.avd.auditallow &= ~perms; 811 break; 812 case AVC_CALLBACK_AUDITDENY_ENABLE: 813 node->ae.avd.auditdeny |= perms; 814 break; 815 case AVC_CALLBACK_AUDITDENY_DISABLE: 816 node->ae.avd.auditdeny &= ~perms; 817 break; 818 } 819 avc_node_replace(node, orig); 820out_unlock: 821 spin_unlock_irqrestore(lock, flag); 822out: 823 return rc; 824} 825 826/** 827 * avc_ss_reset - Flush the cache and revalidate migrated permissions. 828 * @seqno: policy sequence number 829 */ 830int avc_ss_reset(u32 seqno) 831{ 832 struct avc_callback_node *c; 833 int i, rc = 0, tmprc; 834 unsigned long flag; 835 struct avc_node *node; 836 struct hlist_head *head; 837 struct hlist_node *next; 838 spinlock_t *lock; 839 840 for (i = 0; i < AVC_CACHE_SLOTS; i++) { 841 head = &avc_cache.slots[i]; 842 lock = &avc_cache.slots_lock[i]; 843 844 spin_lock_irqsave(lock, flag); 845 /* 846 * With preemptable RCU, the outer spinlock does not 847 * prevent RCU grace periods from ending. 848 */ 849 rcu_read_lock(); 850 hlist_for_each_entry(node, next, head, list) 851 avc_node_delete(node); 852 rcu_read_unlock(); 853 spin_unlock_irqrestore(lock, flag); 854 } 855 856 for (c = avc_callbacks; c; c = c->next) { 857 if (c->events & AVC_CALLBACK_RESET) { 858 tmprc = c->callback(AVC_CALLBACK_RESET, 859 0, 0, 0, 0, NULL); 860 /* save the first error encountered for the return 861 value and continue processing the callbacks */ 862 if (!rc) 863 rc = tmprc; 864 } 865 } 866 867 avc_latest_notif_update(seqno, 0); 868 return rc; 869} 870 871/** 872 * avc_has_perm_noaudit - Check permissions but perform no auditing. 873 * @ssid: source security identifier 874 * @tsid: target security identifier 875 * @tclass: target security class 876 * @requested: requested permissions, interpreted based on @tclass 877 * @flags: AVC_STRICT or 0 878 * @avd: access vector decisions 879 * 880 * Check the AVC to determine whether the @requested permissions are granted 881 * for the SID pair (@ssid, @tsid), interpreting the permissions 882 * based on @tclass, and call the security server on a cache miss to obtain 883 * a new decision and add it to the cache. Return a copy of the decisions 884 * in @avd. Return %0 if all @requested permissions are granted, 885 * -%EACCES if any permissions are denied, or another -errno upon 886 * other errors. This function is typically called by avc_has_perm(), 887 * but may also be called directly to separate permission checking from 888 * auditing, e.g. in cases where a lock must be held for the check but 889 * should be released for the auditing. 890 */ 891int avc_has_perm_noaudit(u32 ssid, u32 tsid, 892 u16 tclass, u32 requested, 893 unsigned flags, 894 struct av_decision *in_avd) 895{ 896 struct avc_node *node; 897 struct av_decision avd_entry, *avd; 898 int rc = 0; 899 u32 denied; 900 901 BUG_ON(!requested); 902 903 rcu_read_lock(); 904 905 node = avc_lookup(ssid, tsid, tclass); 906 if (!node) { 907 rcu_read_unlock(); 908 909 if (in_avd) 910 avd = in_avd; 911 else 912 avd = &avd_entry; 913 914 rc = security_compute_av(ssid, tsid, tclass, requested, avd); 915 if (rc) 916 goto out; 917 rcu_read_lock(); 918 node = avc_insert(ssid, tsid, tclass, avd); 919 } else { 920 if (in_avd) 921 memcpy(in_avd, &node->ae.avd, sizeof(*in_avd)); 922 avd = &node->ae.avd; 923 } 924 925 denied = requested & ~(avd->allowed); 926 927 if (denied) { 928 if (flags & AVC_STRICT) 929 rc = -EACCES; 930 else if (!selinux_enforcing || (avd->flags & AVD_FLAGS_PERMISSIVE)) 931 avc_update_node(AVC_CALLBACK_GRANT, requested, ssid, 932 tsid, tclass, avd->seqno); 933 else 934 rc = -EACCES; 935 } 936 937 rcu_read_unlock(); 938out: 939 return rc; 940} 941 942/** 943 * avc_has_perm - Check permissions and perform any appropriate auditing. 944 * @ssid: source security identifier 945 * @tsid: target security identifier 946 * @tclass: target security class 947 * @requested: requested permissions, interpreted based on @tclass 948 * @auditdata: auxiliary audit data 949 * 950 * Check the AVC to determine whether the @requested permissions are granted 951 * for the SID pair (@ssid, @tsid), interpreting the permissions 952 * based on @tclass, and call the security server on a cache miss to obtain 953 * a new decision and add it to the cache. Audit the granting or denial of 954 * permissions in accordance with the policy. Return %0 if all @requested 955 * permissions are granted, -%EACCES if any permissions are denied, or 956 * another -errno upon other errors. 957 */ 958int avc_has_perm(u32 ssid, u32 tsid, u16 tclass, 959 u32 requested, struct avc_audit_data *auditdata) 960{ 961 struct av_decision avd; 962 int rc; 963 964 rc = avc_has_perm_noaudit(ssid, tsid, tclass, requested, 0, &avd); 965 avc_audit(ssid, tsid, tclass, requested, &avd, rc, auditdata); 966 return rc; 967} 968 969u32 avc_policy_seqno(void) 970{ 971 return avc_cache.latest_notif; 972} 973 974void avc_disable(void) 975{ 976 if (avc_node_cachep) 977 kmem_cache_destroy(avc_node_cachep); 978} 979