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 static 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 audit_log_format(ab, " tclass=%s", class_to_string[tclass]); 221 } 222 223 /** 224 * avc_init - Initialize the AVC. 225 * 226 * Initialize the access vector cache. 227 */ 228 void __init avc_init(void) 229 { 230 int i; 231 232 for (i = 0; i < AVC_CACHE_SLOTS; i++) { 233 INIT_LIST_HEAD(&avc_cache.slots[i]); 234 spin_lock_init(&avc_cache.slots_lock[i]); 235 } 236 atomic_set(&avc_cache.active_nodes, 0); 237 atomic_set(&avc_cache.lru_hint, 0); 238 239 avc_node_cachep = kmem_cache_create("avc_node", sizeof(struct avc_node), 240 0, SLAB_PANIC, NULL, NULL); 241 242 audit_log(current->audit_context, GFP_KERNEL, AUDIT_KERNEL, "AVC INITIALIZED\n"); 243 } 244 245 int avc_get_hash_stats(char *page) 246 { 247 int i, chain_len, max_chain_len, slots_used; 248 struct avc_node *node; 249 250 rcu_read_lock(); 251 252 slots_used = 0; 253 max_chain_len = 0; 254 for (i = 0; i < AVC_CACHE_SLOTS; i++) { 255 if (!list_empty(&avc_cache.slots[i])) { 256 slots_used++; 257 chain_len = 0; 258 list_for_each_entry_rcu(node, &avc_cache.slots[i], list) 259 chain_len++; 260 if (chain_len > max_chain_len) 261 max_chain_len = chain_len; 262 } 263 } 264 265 rcu_read_unlock(); 266 267 return scnprintf(page, PAGE_SIZE, "entries: %d\nbuckets used: %d/%d\n" 268 "longest chain: %d\n", 269 atomic_read(&avc_cache.active_nodes), 270 slots_used, AVC_CACHE_SLOTS, max_chain_len); 271 } 272 273 static void avc_node_free(struct rcu_head *rhead) 274 { 275 struct avc_node *node = container_of(rhead, struct avc_node, rhead); 276 kmem_cache_free(avc_node_cachep, node); 277 avc_cache_stats_incr(frees); 278 } 279 280 static void avc_node_delete(struct avc_node *node) 281 { 282 list_del_rcu(&node->list); 283 call_rcu(&node->rhead, avc_node_free); 284 atomic_dec(&avc_cache.active_nodes); 285 } 286 287 static void avc_node_kill(struct avc_node *node) 288 { 289 kmem_cache_free(avc_node_cachep, node); 290 avc_cache_stats_incr(frees); 291 atomic_dec(&avc_cache.active_nodes); 292 } 293 294 static void avc_node_replace(struct avc_node *new, struct avc_node *old) 295 { 296 list_replace_rcu(&old->list, &new->list); 297 call_rcu(&old->rhead, avc_node_free); 298 atomic_dec(&avc_cache.active_nodes); 299 } 300 301 static inline int avc_reclaim_node(void) 302 { 303 struct avc_node *node; 304 int hvalue, try, ecx; 305 unsigned long flags; 306 307 for (try = 0, ecx = 0; try < AVC_CACHE_SLOTS; try++ ) { 308 hvalue = atomic_inc_return(&avc_cache.lru_hint) & (AVC_CACHE_SLOTS - 1); 309 310 if (!spin_trylock_irqsave(&avc_cache.slots_lock[hvalue], flags)) 311 continue; 312 313 list_for_each_entry(node, &avc_cache.slots[hvalue], list) { 314 if (atomic_dec_and_test(&node->ae.used)) { 315 /* Recently Unused */ 316 avc_node_delete(node); 317 avc_cache_stats_incr(reclaims); 318 ecx++; 319 if (ecx >= AVC_CACHE_RECLAIM) { 320 spin_unlock_irqrestore(&avc_cache.slots_lock[hvalue], flags); 321 goto out; 322 } 323 } 324 } 325 spin_unlock_irqrestore(&avc_cache.slots_lock[hvalue], flags); 326 } 327 out: 328 return ecx; 329 } 330 331 static struct avc_node *avc_alloc_node(void) 332 { 333 struct avc_node *node; 334 335 node = kmem_cache_zalloc(avc_node_cachep, GFP_ATOMIC); 336 if (!node) 337 goto out; 338 339 INIT_RCU_HEAD(&node->rhead); 340 INIT_LIST_HEAD(&node->list); 341 atomic_set(&node->ae.used, 1); 342 avc_cache_stats_incr(allocations); 343 344 if (atomic_inc_return(&avc_cache.active_nodes) > avc_cache_threshold) 345 avc_reclaim_node(); 346 347 out: 348 return node; 349 } 350 351 static void avc_node_populate(struct avc_node *node, u32 ssid, u32 tsid, u16 tclass, struct avc_entry *ae) 352 { 353 node->ae.ssid = ssid; 354 node->ae.tsid = tsid; 355 node->ae.tclass = tclass; 356 memcpy(&node->ae.avd, &ae->avd, sizeof(node->ae.avd)); 357 } 358 359 static inline struct avc_node *avc_search_node(u32 ssid, u32 tsid, u16 tclass) 360 { 361 struct avc_node *node, *ret = NULL; 362 int hvalue; 363 364 hvalue = avc_hash(ssid, tsid, tclass); 365 list_for_each_entry_rcu(node, &avc_cache.slots[hvalue], list) { 366 if (ssid == node->ae.ssid && 367 tclass == node->ae.tclass && 368 tsid == node->ae.tsid) { 369 ret = node; 370 break; 371 } 372 } 373 374 if (ret == NULL) { 375 /* cache miss */ 376 goto out; 377 } 378 379 /* cache hit */ 380 if (atomic_read(&ret->ae.used) != 1) 381 atomic_set(&ret->ae.used, 1); 382 out: 383 return ret; 384 } 385 386 /** 387 * avc_lookup - Look up an AVC entry. 388 * @ssid: source security identifier 389 * @tsid: target security identifier 390 * @tclass: target security class 391 * @requested: requested permissions, interpreted based on @tclass 392 * 393 * Look up an AVC entry that is valid for the 394 * @requested permissions between the SID pair 395 * (@ssid, @tsid), interpreting the permissions 396 * based on @tclass. If a valid AVC entry exists, 397 * then this function return the avc_node. 398 * Otherwise, this function returns NULL. 399 */ 400 static struct avc_node *avc_lookup(u32 ssid, u32 tsid, u16 tclass, u32 requested) 401 { 402 struct avc_node *node; 403 404 avc_cache_stats_incr(lookups); 405 node = avc_search_node(ssid, tsid, tclass); 406 407 if (node && ((node->ae.avd.decided & requested) == requested)) { 408 avc_cache_stats_incr(hits); 409 goto out; 410 } 411 412 node = NULL; 413 avc_cache_stats_incr(misses); 414 out: 415 return node; 416 } 417 418 static 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 "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 * @ae: AVC entry 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 @ae->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 */ 457 static struct avc_node *avc_insert(u32 ssid, u32 tsid, u16 tclass, struct avc_entry *ae) 458 { 459 struct avc_node *pos, *node = NULL; 460 int hvalue; 461 unsigned long flag; 462 463 if (avc_latest_notif_update(ae->avd.seqno, 1)) 464 goto out; 465 466 node = avc_alloc_node(); 467 if (node) { 468 hvalue = avc_hash(ssid, tsid, tclass); 469 avc_node_populate(node, ssid, tsid, tclass, ae); 470 471 spin_lock_irqsave(&avc_cache.slots_lock[hvalue], flag); 472 list_for_each_entry(pos, &avc_cache.slots[hvalue], list) { 473 if (pos->ae.ssid == ssid && 474 pos->ae.tsid == tsid && 475 pos->ae.tclass == tclass) { 476 avc_node_replace(node, pos); 477 goto found; 478 } 479 } 480 list_add_rcu(&node->list, &avc_cache.slots[hvalue]); 481 found: 482 spin_unlock_irqrestore(&avc_cache.slots_lock[hvalue], flag); 483 } 484 out: 485 return node; 486 } 487 488 static inline void avc_print_ipv6_addr(struct audit_buffer *ab, 489 struct in6_addr *addr, __be16 port, 490 char *name1, char *name2) 491 { 492 if (!ipv6_addr_any(addr)) 493 audit_log_format(ab, " %s=" NIP6_FMT, name1, NIP6(*addr)); 494 if (port) 495 audit_log_format(ab, " %s=%d", name2, ntohs(port)); 496 } 497 498 static inline void avc_print_ipv4_addr(struct audit_buffer *ab, __be32 addr, 499 __be16 port, char *name1, char *name2) 500 { 501 if (addr) 502 audit_log_format(ab, " %s=" NIPQUAD_FMT, name1, NIPQUAD(addr)); 503 if (port) 504 audit_log_format(ab, " %s=%d", name2, ntohs(port)); 505 } 506 507 /** 508 * avc_audit - Audit the granting or denial of permissions. 509 * @ssid: source security identifier 510 * @tsid: target security identifier 511 * @tclass: target security class 512 * @requested: requested permissions 513 * @avd: access vector decisions 514 * @result: result from avc_has_perm_noaudit 515 * @a: auxiliary audit data 516 * 517 * Audit the granting or denial of permissions in accordance 518 * with the policy. This function is typically called by 519 * avc_has_perm() after a permission check, but can also be 520 * called directly by callers who use avc_has_perm_noaudit() 521 * in order to separate the permission check from the auditing. 522 * For example, this separation is useful when the permission check must 523 * be performed under a lock, to allow the lock to be released 524 * before calling the auditing code. 525 */ 526 void avc_audit(u32 ssid, u32 tsid, 527 u16 tclass, u32 requested, 528 struct av_decision *avd, int result, struct avc_audit_data *a) 529 { 530 struct task_struct *tsk = current; 531 struct inode *inode = NULL; 532 u32 denied, audited; 533 struct audit_buffer *ab; 534 535 denied = requested & ~avd->allowed; 536 if (denied) { 537 audited = denied; 538 if (!(audited & avd->auditdeny)) 539 return; 540 } else if (result) { 541 audited = denied = requested; 542 } else { 543 audited = requested; 544 if (!(audited & avd->auditallow)) 545 return; 546 } 547 548 ab = audit_log_start(current->audit_context, GFP_ATOMIC, AUDIT_AVC); 549 if (!ab) 550 return; /* audit_panic has been called */ 551 audit_log_format(ab, "avc: %s ", denied ? "denied" : "granted"); 552 avc_dump_av(ab, tclass,audited); 553 audit_log_format(ab, " for "); 554 if (a && a->tsk) 555 tsk = a->tsk; 556 if (tsk && tsk->pid) { 557 audit_log_format(ab, " pid=%d comm=", tsk->pid); 558 audit_log_untrustedstring(ab, tsk->comm); 559 } 560 if (a) { 561 switch (a->type) { 562 case AVC_AUDIT_DATA_IPC: 563 audit_log_format(ab, " key=%d", a->u.ipc_id); 564 break; 565 case AVC_AUDIT_DATA_CAP: 566 audit_log_format(ab, " capability=%d", a->u.cap); 567 break; 568 case AVC_AUDIT_DATA_FS: 569 if (a->u.fs.dentry) { 570 struct dentry *dentry = a->u.fs.dentry; 571 if (a->u.fs.mnt) 572 audit_avc_path(dentry, a->u.fs.mnt); 573 audit_log_format(ab, " name="); 574 audit_log_untrustedstring(ab, dentry->d_name.name); 575 inode = dentry->d_inode; 576 } else if (a->u.fs.inode) { 577 struct dentry *dentry; 578 inode = a->u.fs.inode; 579 dentry = d_find_alias(inode); 580 if (dentry) { 581 audit_log_format(ab, " name="); 582 audit_log_untrustedstring(ab, dentry->d_name.name); 583 dput(dentry); 584 } 585 } 586 if (inode) 587 audit_log_format(ab, " dev=%s ino=%ld", 588 inode->i_sb->s_id, 589 inode->i_ino); 590 break; 591 case AVC_AUDIT_DATA_NET: 592 if (a->u.net.sk) { 593 struct sock *sk = a->u.net.sk; 594 struct unix_sock *u; 595 int len = 0; 596 char *p = NULL; 597 598 switch (sk->sk_family) { 599 case AF_INET: { 600 struct inet_sock *inet = inet_sk(sk); 601 602 avc_print_ipv4_addr(ab, inet->rcv_saddr, 603 inet->sport, 604 "laddr", "lport"); 605 avc_print_ipv4_addr(ab, inet->daddr, 606 inet->dport, 607 "faddr", "fport"); 608 break; 609 } 610 case AF_INET6: { 611 struct inet_sock *inet = inet_sk(sk); 612 struct ipv6_pinfo *inet6 = inet6_sk(sk); 613 614 avc_print_ipv6_addr(ab, &inet6->rcv_saddr, 615 inet->sport, 616 "laddr", "lport"); 617 avc_print_ipv6_addr(ab, &inet6->daddr, 618 inet->dport, 619 "faddr", "fport"); 620 break; 621 } 622 case AF_UNIX: 623 u = unix_sk(sk); 624 if (u->dentry) { 625 audit_avc_path(u->dentry, u->mnt); 626 audit_log_format(ab, " name="); 627 audit_log_untrustedstring(ab, u->dentry->d_name.name); 628 break; 629 } 630 if (!u->addr) 631 break; 632 len = u->addr->len-sizeof(short); 633 p = &u->addr->name->sun_path[0]; 634 audit_log_format(ab, " path="); 635 if (*p) 636 audit_log_untrustedstring(ab, p); 637 else 638 audit_log_hex(ab, p, len); 639 break; 640 } 641 } 642 643 switch (a->u.net.family) { 644 case AF_INET: 645 avc_print_ipv4_addr(ab, a->u.net.v4info.saddr, 646 a->u.net.sport, 647 "saddr", "src"); 648 avc_print_ipv4_addr(ab, a->u.net.v4info.daddr, 649 a->u.net.dport, 650 "daddr", "dest"); 651 break; 652 case AF_INET6: 653 avc_print_ipv6_addr(ab, &a->u.net.v6info.saddr, 654 a->u.net.sport, 655 "saddr", "src"); 656 avc_print_ipv6_addr(ab, &a->u.net.v6info.daddr, 657 a->u.net.dport, 658 "daddr", "dest"); 659 break; 660 } 661 if (a->u.net.netif) 662 audit_log_format(ab, " netif=%s", 663 a->u.net.netif); 664 break; 665 } 666 } 667 audit_log_format(ab, " "); 668 avc_dump_query(ab, ssid, tsid, tclass); 669 audit_log_end(ab); 670 } 671 672 /** 673 * avc_add_callback - Register a callback for security events. 674 * @callback: callback function 675 * @events: security events 676 * @ssid: source security identifier or %SECSID_WILD 677 * @tsid: target security identifier or %SECSID_WILD 678 * @tclass: target security class 679 * @perms: permissions 680 * 681 * Register a callback function for events in the set @events 682 * related to the SID pair (@ssid, @tsid) and 683 * and the permissions @perms, interpreting 684 * @perms based on @tclass. Returns %0 on success or 685 * -%ENOMEM if insufficient memory exists to add the callback. 686 */ 687 int avc_add_callback(int (*callback)(u32 event, u32 ssid, u32 tsid, 688 u16 tclass, u32 perms, 689 u32 *out_retained), 690 u32 events, u32 ssid, u32 tsid, 691 u16 tclass, u32 perms) 692 { 693 struct avc_callback_node *c; 694 int rc = 0; 695 696 c = kmalloc(sizeof(*c), GFP_ATOMIC); 697 if (!c) { 698 rc = -ENOMEM; 699 goto out; 700 } 701 702 c->callback = callback; 703 c->events = events; 704 c->ssid = ssid; 705 c->tsid = tsid; 706 c->perms = perms; 707 c->next = avc_callbacks; 708 avc_callbacks = c; 709 out: 710 return rc; 711 } 712 713 static inline int avc_sidcmp(u32 x, u32 y) 714 { 715 return (x == y || x == SECSID_WILD || y == SECSID_WILD); 716 } 717 718 /** 719 * avc_update_node Update an AVC entry 720 * @event : Updating event 721 * @perms : Permission mask bits 722 * @ssid,@tsid,@tclass : identifier of an AVC entry 723 * 724 * if a valid AVC entry doesn't exist,this function returns -ENOENT. 725 * if kmalloc() called internal returns NULL, this function returns -ENOMEM. 726 * otherwise, this function update the AVC entry. The original AVC-entry object 727 * will release later by RCU. 728 */ 729 static int avc_update_node(u32 event, u32 perms, u32 ssid, u32 tsid, u16 tclass) 730 { 731 int hvalue, rc = 0; 732 unsigned long flag; 733 struct avc_node *pos, *node, *orig = NULL; 734 735 node = avc_alloc_node(); 736 if (!node) { 737 rc = -ENOMEM; 738 goto out; 739 } 740 741 /* Lock the target slot */ 742 hvalue = avc_hash(ssid, tsid, tclass); 743 spin_lock_irqsave(&avc_cache.slots_lock[hvalue], flag); 744 745 list_for_each_entry(pos, &avc_cache.slots[hvalue], list){ 746 if ( ssid==pos->ae.ssid && 747 tsid==pos->ae.tsid && 748 tclass==pos->ae.tclass ){ 749 orig = pos; 750 break; 751 } 752 } 753 754 if (!orig) { 755 rc = -ENOENT; 756 avc_node_kill(node); 757 goto out_unlock; 758 } 759 760 /* 761 * Copy and replace original node. 762 */ 763 764 avc_node_populate(node, ssid, tsid, tclass, &orig->ae); 765 766 switch (event) { 767 case AVC_CALLBACK_GRANT: 768 node->ae.avd.allowed |= perms; 769 break; 770 case AVC_CALLBACK_TRY_REVOKE: 771 case AVC_CALLBACK_REVOKE: 772 node->ae.avd.allowed &= ~perms; 773 break; 774 case AVC_CALLBACK_AUDITALLOW_ENABLE: 775 node->ae.avd.auditallow |= perms; 776 break; 777 case AVC_CALLBACK_AUDITALLOW_DISABLE: 778 node->ae.avd.auditallow &= ~perms; 779 break; 780 case AVC_CALLBACK_AUDITDENY_ENABLE: 781 node->ae.avd.auditdeny |= perms; 782 break; 783 case AVC_CALLBACK_AUDITDENY_DISABLE: 784 node->ae.avd.auditdeny &= ~perms; 785 break; 786 } 787 avc_node_replace(node, orig); 788 out_unlock: 789 spin_unlock_irqrestore(&avc_cache.slots_lock[hvalue], flag); 790 out: 791 return rc; 792 } 793 794 /** 795 * avc_ss_reset - Flush the cache and revalidate migrated permissions. 796 * @seqno: policy sequence number 797 */ 798 int avc_ss_reset(u32 seqno) 799 { 800 struct avc_callback_node *c; 801 int i, rc = 0, tmprc; 802 unsigned long flag; 803 struct avc_node *node; 804 805 for (i = 0; i < AVC_CACHE_SLOTS; i++) { 806 spin_lock_irqsave(&avc_cache.slots_lock[i], flag); 807 list_for_each_entry(node, &avc_cache.slots[i], list) 808 avc_node_delete(node); 809 spin_unlock_irqrestore(&avc_cache.slots_lock[i], flag); 810 } 811 812 for (c = avc_callbacks; c; c = c->next) { 813 if (c->events & AVC_CALLBACK_RESET) { 814 tmprc = c->callback(AVC_CALLBACK_RESET, 815 0, 0, 0, 0, NULL); 816 /* save the first error encountered for the return 817 value and continue processing the callbacks */ 818 if (!rc) 819 rc = tmprc; 820 } 821 } 822 823 avc_latest_notif_update(seqno, 0); 824 return rc; 825 } 826 827 /** 828 * avc_has_perm_noaudit - Check permissions but perform no auditing. 829 * @ssid: source security identifier 830 * @tsid: target security identifier 831 * @tclass: target security class 832 * @requested: requested permissions, interpreted based on @tclass 833 * @avd: access vector decisions 834 * 835 * Check the AVC to determine whether the @requested permissions are granted 836 * for the SID pair (@ssid, @tsid), interpreting the permissions 837 * based on @tclass, and call the security server on a cache miss to obtain 838 * a new decision and add it to the cache. Return a copy of the decisions 839 * in @avd. Return %0 if all @requested permissions are granted, 840 * -%EACCES if any permissions are denied, or another -errno upon 841 * other errors. This function is typically called by avc_has_perm(), 842 * but may also be called directly to separate permission checking from 843 * auditing, e.g. in cases where a lock must be held for the check but 844 * should be released for the auditing. 845 */ 846 int avc_has_perm_noaudit(u32 ssid, u32 tsid, 847 u16 tclass, u32 requested, 848 struct av_decision *avd) 849 { 850 struct avc_node *node; 851 struct avc_entry entry, *p_ae; 852 int rc = 0; 853 u32 denied; 854 855 rcu_read_lock(); 856 857 node = avc_lookup(ssid, tsid, tclass, requested); 858 if (!node) { 859 rcu_read_unlock(); 860 rc = security_compute_av(ssid,tsid,tclass,requested,&entry.avd); 861 if (rc) 862 goto out; 863 rcu_read_lock(); 864 node = avc_insert(ssid,tsid,tclass,&entry); 865 } 866 867 p_ae = node ? &node->ae : &entry; 868 869 if (avd) 870 memcpy(avd, &p_ae->avd, sizeof(*avd)); 871 872 denied = requested & ~(p_ae->avd.allowed); 873 874 if (!requested || denied) { 875 if (selinux_enforcing) 876 rc = -EACCES; 877 else 878 if (node) 879 avc_update_node(AVC_CALLBACK_GRANT,requested, 880 ssid,tsid,tclass); 881 } 882 883 rcu_read_unlock(); 884 out: 885 return rc; 886 } 887 888 /** 889 * avc_has_perm - Check permissions and perform any appropriate auditing. 890 * @ssid: source security identifier 891 * @tsid: target security identifier 892 * @tclass: target security class 893 * @requested: requested permissions, interpreted based on @tclass 894 * @auditdata: auxiliary audit data 895 * 896 * Check the AVC to determine whether the @requested permissions are granted 897 * for the SID pair (@ssid, @tsid), interpreting the permissions 898 * based on @tclass, and call the security server on a cache miss to obtain 899 * a new decision and add it to the cache. Audit the granting or denial of 900 * permissions in accordance with the policy. Return %0 if all @requested 901 * permissions are granted, -%EACCES if any permissions are denied, or 902 * another -errno upon other errors. 903 */ 904 int avc_has_perm(u32 ssid, u32 tsid, u16 tclass, 905 u32 requested, struct avc_audit_data *auditdata) 906 { 907 struct av_decision avd; 908 int rc; 909 910 rc = avc_has_perm_noaudit(ssid, tsid, tclass, requested, &avd); 911 avc_audit(ssid, tsid, tclass, requested, &avd, rc, auditdata); 912 return rc; 913 } 914