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_alloc(avc_node_cachep, GFP_ATOMIC); 336 if (!node) 337 goto out; 338 339 memset(node, 0, sizeof(*node)); 340 INIT_RCU_HEAD(&node->rhead); 341 INIT_LIST_HEAD(&node->list); 342 atomic_set(&node->ae.used, 1); 343 avc_cache_stats_incr(allocations); 344 345 if (atomic_inc_return(&avc_cache.active_nodes) > avc_cache_threshold) 346 avc_reclaim_node(); 347 348 out: 349 return node; 350 } 351 352 static void avc_node_populate(struct avc_node *node, u32 ssid, u32 tsid, u16 tclass, struct avc_entry *ae) 353 { 354 node->ae.ssid = ssid; 355 node->ae.tsid = tsid; 356 node->ae.tclass = tclass; 357 memcpy(&node->ae.avd, &ae->avd, sizeof(node->ae.avd)); 358 } 359 360 static inline struct avc_node *avc_search_node(u32 ssid, u32 tsid, u16 tclass) 361 { 362 struct avc_node *node, *ret = NULL; 363 int hvalue; 364 365 hvalue = avc_hash(ssid, tsid, tclass); 366 list_for_each_entry_rcu(node, &avc_cache.slots[hvalue], list) { 367 if (ssid == node->ae.ssid && 368 tclass == node->ae.tclass && 369 tsid == node->ae.tsid) { 370 ret = node; 371 break; 372 } 373 } 374 375 if (ret == NULL) { 376 /* cache miss */ 377 goto out; 378 } 379 380 /* cache hit */ 381 if (atomic_read(&ret->ae.used) != 1) 382 atomic_set(&ret->ae.used, 1); 383 out: 384 return ret; 385 } 386 387 /** 388 * avc_lookup - Look up an AVC entry. 389 * @ssid: source security identifier 390 * @tsid: target security identifier 391 * @tclass: target security class 392 * @requested: requested permissions, interpreted based on @tclass 393 * 394 * Look up an AVC entry that is valid for the 395 * @requested permissions between the SID pair 396 * (@ssid, @tsid), interpreting the permissions 397 * based on @tclass. If a valid AVC entry exists, 398 * then this function return the avc_node. 399 * Otherwise, this function returns NULL. 400 */ 401 static struct avc_node *avc_lookup(u32 ssid, u32 tsid, u16 tclass, u32 requested) 402 { 403 struct avc_node *node; 404 405 avc_cache_stats_incr(lookups); 406 node = avc_search_node(ssid, tsid, tclass); 407 408 if (node && ((node->ae.avd.decided & requested) == requested)) { 409 avc_cache_stats_incr(hits); 410 goto out; 411 } 412 413 node = NULL; 414 avc_cache_stats_incr(misses); 415 out: 416 return node; 417 } 418 419 static int avc_latest_notif_update(int seqno, int is_insert) 420 { 421 int ret = 0; 422 static DEFINE_SPINLOCK(notif_lock); 423 unsigned long flag; 424 425 spin_lock_irqsave(¬if_lock, flag); 426 if (is_insert) { 427 if (seqno < avc_cache.latest_notif) { 428 printk(KERN_WARNING "avc: seqno %d < latest_notif %d\n", 429 seqno, avc_cache.latest_notif); 430 ret = -EAGAIN; 431 } 432 } else { 433 if (seqno > avc_cache.latest_notif) 434 avc_cache.latest_notif = seqno; 435 } 436 spin_unlock_irqrestore(¬if_lock, flag); 437 438 return ret; 439 } 440 441 /** 442 * avc_insert - Insert an AVC entry. 443 * @ssid: source security identifier 444 * @tsid: target security identifier 445 * @tclass: target security class 446 * @ae: AVC entry 447 * 448 * Insert an AVC entry for the SID pair 449 * (@ssid, @tsid) and class @tclass. 450 * The access vectors and the sequence number are 451 * normally provided by the security server in 452 * response to a security_compute_av() call. If the 453 * sequence number @ae->avd.seqno is not less than the latest 454 * revocation notification, then the function copies 455 * the access vectors into a cache entry, returns 456 * avc_node inserted. Otherwise, this function returns NULL. 457 */ 458 static struct avc_node *avc_insert(u32 ssid, u32 tsid, u16 tclass, struct avc_entry *ae) 459 { 460 struct avc_node *pos, *node = NULL; 461 int hvalue; 462 unsigned long flag; 463 464 if (avc_latest_notif_update(ae->avd.seqno, 1)) 465 goto out; 466 467 node = avc_alloc_node(); 468 if (node) { 469 hvalue = avc_hash(ssid, tsid, tclass); 470 avc_node_populate(node, ssid, tsid, tclass, ae); 471 472 spin_lock_irqsave(&avc_cache.slots_lock[hvalue], flag); 473 list_for_each_entry(pos, &avc_cache.slots[hvalue], list) { 474 if (pos->ae.ssid == ssid && 475 pos->ae.tsid == tsid && 476 pos->ae.tclass == tclass) { 477 avc_node_replace(node, pos); 478 goto found; 479 } 480 } 481 list_add_rcu(&node->list, &avc_cache.slots[hvalue]); 482 found: 483 spin_unlock_irqrestore(&avc_cache.slots_lock[hvalue], flag); 484 } 485 out: 486 return node; 487 } 488 489 static inline void avc_print_ipv6_addr(struct audit_buffer *ab, 490 struct in6_addr *addr, __be16 port, 491 char *name1, char *name2) 492 { 493 if (!ipv6_addr_any(addr)) 494 audit_log_format(ab, " %s=" NIP6_FMT, name1, NIP6(*addr)); 495 if (port) 496 audit_log_format(ab, " %s=%d", name2, ntohs(port)); 497 } 498 499 static inline void avc_print_ipv4_addr(struct audit_buffer *ab, __be32 addr, 500 __be16 port, char *name1, char *name2) 501 { 502 if (addr) 503 audit_log_format(ab, " %s=" NIPQUAD_FMT, name1, NIPQUAD(addr)); 504 if (port) 505 audit_log_format(ab, " %s=%d", name2, ntohs(port)); 506 } 507 508 /** 509 * avc_audit - Audit the granting or denial of permissions. 510 * @ssid: source security identifier 511 * @tsid: target security identifier 512 * @tclass: target security class 513 * @requested: requested permissions 514 * @avd: access vector decisions 515 * @result: result from avc_has_perm_noaudit 516 * @a: auxiliary audit data 517 * 518 * Audit the granting or denial of permissions in accordance 519 * with the policy. This function is typically called by 520 * avc_has_perm() after a permission check, but can also be 521 * called directly by callers who use avc_has_perm_noaudit() 522 * in order to separate the permission check from the auditing. 523 * For example, this separation is useful when the permission check must 524 * be performed under a lock, to allow the lock to be released 525 * before calling the auditing code. 526 */ 527 void avc_audit(u32 ssid, u32 tsid, 528 u16 tclass, u32 requested, 529 struct av_decision *avd, int result, struct avc_audit_data *a) 530 { 531 struct task_struct *tsk = current; 532 struct inode *inode = NULL; 533 u32 denied, audited; 534 struct audit_buffer *ab; 535 536 denied = requested & ~avd->allowed; 537 if (denied) { 538 audited = denied; 539 if (!(audited & avd->auditdeny)) 540 return; 541 } else if (result) { 542 audited = denied = requested; 543 } else { 544 audited = requested; 545 if (!(audited & avd->auditallow)) 546 return; 547 } 548 549 ab = audit_log_start(current->audit_context, GFP_ATOMIC, AUDIT_AVC); 550 if (!ab) 551 return; /* audit_panic has been called */ 552 audit_log_format(ab, "avc: %s ", denied ? "denied" : "granted"); 553 avc_dump_av(ab, tclass,audited); 554 audit_log_format(ab, " for "); 555 if (a && a->tsk) 556 tsk = a->tsk; 557 if (tsk && tsk->pid) { 558 audit_log_format(ab, " pid=%d comm=", tsk->pid); 559 audit_log_untrustedstring(ab, tsk->comm); 560 } 561 if (a) { 562 switch (a->type) { 563 case AVC_AUDIT_DATA_IPC: 564 audit_log_format(ab, " key=%d", a->u.ipc_id); 565 break; 566 case AVC_AUDIT_DATA_CAP: 567 audit_log_format(ab, " capability=%d", a->u.cap); 568 break; 569 case AVC_AUDIT_DATA_FS: 570 if (a->u.fs.dentry) { 571 struct dentry *dentry = a->u.fs.dentry; 572 if (a->u.fs.mnt) 573 audit_avc_path(dentry, a->u.fs.mnt); 574 audit_log_format(ab, " name="); 575 audit_log_untrustedstring(ab, dentry->d_name.name); 576 inode = dentry->d_inode; 577 } else if (a->u.fs.inode) { 578 struct dentry *dentry; 579 inode = a->u.fs.inode; 580 dentry = d_find_alias(inode); 581 if (dentry) { 582 audit_log_format(ab, " name="); 583 audit_log_untrustedstring(ab, dentry->d_name.name); 584 dput(dentry); 585 } 586 } 587 if (inode) 588 audit_log_format(ab, " dev=%s ino=%ld", 589 inode->i_sb->s_id, 590 inode->i_ino); 591 break; 592 case AVC_AUDIT_DATA_NET: 593 if (a->u.net.sk) { 594 struct sock *sk = a->u.net.sk; 595 struct unix_sock *u; 596 int len = 0; 597 char *p = NULL; 598 599 switch (sk->sk_family) { 600 case AF_INET: { 601 struct inet_sock *inet = inet_sk(sk); 602 603 avc_print_ipv4_addr(ab, inet->rcv_saddr, 604 inet->sport, 605 "laddr", "lport"); 606 avc_print_ipv4_addr(ab, inet->daddr, 607 inet->dport, 608 "faddr", "fport"); 609 break; 610 } 611 case AF_INET6: { 612 struct inet_sock *inet = inet_sk(sk); 613 struct ipv6_pinfo *inet6 = inet6_sk(sk); 614 615 avc_print_ipv6_addr(ab, &inet6->rcv_saddr, 616 inet->sport, 617 "laddr", "lport"); 618 avc_print_ipv6_addr(ab, &inet6->daddr, 619 inet->dport, 620 "faddr", "fport"); 621 break; 622 } 623 case AF_UNIX: 624 u = unix_sk(sk); 625 if (u->dentry) { 626 audit_avc_path(u->dentry, u->mnt); 627 audit_log_format(ab, " name="); 628 audit_log_untrustedstring(ab, u->dentry->d_name.name); 629 break; 630 } 631 if (!u->addr) 632 break; 633 len = u->addr->len-sizeof(short); 634 p = &u->addr->name->sun_path[0]; 635 audit_log_format(ab, " path="); 636 if (*p) 637 audit_log_untrustedstring(ab, p); 638 else 639 audit_log_hex(ab, p, len); 640 break; 641 } 642 } 643 644 switch (a->u.net.family) { 645 case AF_INET: 646 avc_print_ipv4_addr(ab, a->u.net.v4info.saddr, 647 a->u.net.sport, 648 "saddr", "src"); 649 avc_print_ipv4_addr(ab, a->u.net.v4info.daddr, 650 a->u.net.dport, 651 "daddr", "dest"); 652 break; 653 case AF_INET6: 654 avc_print_ipv6_addr(ab, &a->u.net.v6info.saddr, 655 a->u.net.sport, 656 "saddr", "src"); 657 avc_print_ipv6_addr(ab, &a->u.net.v6info.daddr, 658 a->u.net.dport, 659 "daddr", "dest"); 660 break; 661 } 662 if (a->u.net.netif) 663 audit_log_format(ab, " netif=%s", 664 a->u.net.netif); 665 break; 666 } 667 } 668 audit_log_format(ab, " "); 669 avc_dump_query(ab, ssid, tsid, tclass); 670 audit_log_end(ab); 671 } 672 673 /** 674 * avc_add_callback - Register a callback for security events. 675 * @callback: callback function 676 * @events: security events 677 * @ssid: source security identifier or %SECSID_WILD 678 * @tsid: target security identifier or %SECSID_WILD 679 * @tclass: target security class 680 * @perms: permissions 681 * 682 * Register a callback function for events in the set @events 683 * related to the SID pair (@ssid, @tsid) and 684 * and the permissions @perms, interpreting 685 * @perms based on @tclass. Returns %0 on success or 686 * -%ENOMEM if insufficient memory exists to add the callback. 687 */ 688 int avc_add_callback(int (*callback)(u32 event, u32 ssid, u32 tsid, 689 u16 tclass, u32 perms, 690 u32 *out_retained), 691 u32 events, u32 ssid, u32 tsid, 692 u16 tclass, u32 perms) 693 { 694 struct avc_callback_node *c; 695 int rc = 0; 696 697 c = kmalloc(sizeof(*c), GFP_ATOMIC); 698 if (!c) { 699 rc = -ENOMEM; 700 goto out; 701 } 702 703 c->callback = callback; 704 c->events = events; 705 c->ssid = ssid; 706 c->tsid = tsid; 707 c->perms = perms; 708 c->next = avc_callbacks; 709 avc_callbacks = c; 710 out: 711 return rc; 712 } 713 714 static inline int avc_sidcmp(u32 x, u32 y) 715 { 716 return (x == y || x == SECSID_WILD || y == SECSID_WILD); 717 } 718 719 /** 720 * avc_update_node Update an AVC entry 721 * @event : Updating event 722 * @perms : Permission mask bits 723 * @ssid,@tsid,@tclass : identifier of an AVC entry 724 * 725 * if a valid AVC entry doesn't exist,this function returns -ENOENT. 726 * if kmalloc() called internal returns NULL, this function returns -ENOMEM. 727 * otherwise, this function update the AVC entry. The original AVC-entry object 728 * will release later by RCU. 729 */ 730 static int avc_update_node(u32 event, u32 perms, u32 ssid, u32 tsid, u16 tclass) 731 { 732 int hvalue, rc = 0; 733 unsigned long flag; 734 struct avc_node *pos, *node, *orig = NULL; 735 736 node = avc_alloc_node(); 737 if (!node) { 738 rc = -ENOMEM; 739 goto out; 740 } 741 742 /* Lock the target slot */ 743 hvalue = avc_hash(ssid, tsid, tclass); 744 spin_lock_irqsave(&avc_cache.slots_lock[hvalue], flag); 745 746 list_for_each_entry(pos, &avc_cache.slots[hvalue], list){ 747 if ( ssid==pos->ae.ssid && 748 tsid==pos->ae.tsid && 749 tclass==pos->ae.tclass ){ 750 orig = pos; 751 break; 752 } 753 } 754 755 if (!orig) { 756 rc = -ENOENT; 757 avc_node_kill(node); 758 goto out_unlock; 759 } 760 761 /* 762 * Copy and replace original node. 763 */ 764 765 avc_node_populate(node, ssid, tsid, tclass, &orig->ae); 766 767 switch (event) { 768 case AVC_CALLBACK_GRANT: 769 node->ae.avd.allowed |= perms; 770 break; 771 case AVC_CALLBACK_TRY_REVOKE: 772 case AVC_CALLBACK_REVOKE: 773 node->ae.avd.allowed &= ~perms; 774 break; 775 case AVC_CALLBACK_AUDITALLOW_ENABLE: 776 node->ae.avd.auditallow |= perms; 777 break; 778 case AVC_CALLBACK_AUDITALLOW_DISABLE: 779 node->ae.avd.auditallow &= ~perms; 780 break; 781 case AVC_CALLBACK_AUDITDENY_ENABLE: 782 node->ae.avd.auditdeny |= perms; 783 break; 784 case AVC_CALLBACK_AUDITDENY_DISABLE: 785 node->ae.avd.auditdeny &= ~perms; 786 break; 787 } 788 avc_node_replace(node, orig); 789 out_unlock: 790 spin_unlock_irqrestore(&avc_cache.slots_lock[hvalue], flag); 791 out: 792 return rc; 793 } 794 795 /** 796 * avc_ss_reset - Flush the cache and revalidate migrated permissions. 797 * @seqno: policy sequence number 798 */ 799 int avc_ss_reset(u32 seqno) 800 { 801 struct avc_callback_node *c; 802 int i, rc = 0, tmprc; 803 unsigned long flag; 804 struct avc_node *node; 805 806 for (i = 0; i < AVC_CACHE_SLOTS; i++) { 807 spin_lock_irqsave(&avc_cache.slots_lock[i], flag); 808 list_for_each_entry(node, &avc_cache.slots[i], list) 809 avc_node_delete(node); 810 spin_unlock_irqrestore(&avc_cache.slots_lock[i], flag); 811 } 812 813 for (c = avc_callbacks; c; c = c->next) { 814 if (c->events & AVC_CALLBACK_RESET) { 815 tmprc = c->callback(AVC_CALLBACK_RESET, 816 0, 0, 0, 0, NULL); 817 /* save the first error encountered for the return 818 value and continue processing the callbacks */ 819 if (!rc) 820 rc = tmprc; 821 } 822 } 823 824 avc_latest_notif_update(seqno, 0); 825 return rc; 826 } 827 828 /** 829 * avc_has_perm_noaudit - Check permissions but perform no auditing. 830 * @ssid: source security identifier 831 * @tsid: target security identifier 832 * @tclass: target security class 833 * @requested: requested permissions, interpreted based on @tclass 834 * @avd: access vector decisions 835 * 836 * Check the AVC to determine whether the @requested permissions are granted 837 * for the SID pair (@ssid, @tsid), interpreting the permissions 838 * based on @tclass, and call the security server on a cache miss to obtain 839 * a new decision and add it to the cache. Return a copy of the decisions 840 * in @avd. Return %0 if all @requested permissions are granted, 841 * -%EACCES if any permissions are denied, or another -errno upon 842 * other errors. This function is typically called by avc_has_perm(), 843 * but may also be called directly to separate permission checking from 844 * auditing, e.g. in cases where a lock must be held for the check but 845 * should be released for the auditing. 846 */ 847 int avc_has_perm_noaudit(u32 ssid, u32 tsid, 848 u16 tclass, u32 requested, 849 struct av_decision *avd) 850 { 851 struct avc_node *node; 852 struct avc_entry entry, *p_ae; 853 int rc = 0; 854 u32 denied; 855 856 rcu_read_lock(); 857 858 node = avc_lookup(ssid, tsid, tclass, requested); 859 if (!node) { 860 rcu_read_unlock(); 861 rc = security_compute_av(ssid,tsid,tclass,requested,&entry.avd); 862 if (rc) 863 goto out; 864 rcu_read_lock(); 865 node = avc_insert(ssid,tsid,tclass,&entry); 866 } 867 868 p_ae = node ? &node->ae : &entry; 869 870 if (avd) 871 memcpy(avd, &p_ae->avd, sizeof(*avd)); 872 873 denied = requested & ~(p_ae->avd.allowed); 874 875 if (!requested || denied) { 876 if (selinux_enforcing) 877 rc = -EACCES; 878 else 879 if (node) 880 avc_update_node(AVC_CALLBACK_GRANT,requested, 881 ssid,tsid,tclass); 882 } 883 884 rcu_read_unlock(); 885 out: 886 return rc; 887 } 888 889 /** 890 * avc_has_perm - Check permissions and perform any appropriate auditing. 891 * @ssid: source security identifier 892 * @tsid: target security identifier 893 * @tclass: target security class 894 * @requested: requested permissions, interpreted based on @tclass 895 * @auditdata: auxiliary audit data 896 * 897 * Check the AVC to determine whether the @requested permissions are granted 898 * for the SID pair (@ssid, @tsid), interpreting the permissions 899 * based on @tclass, and call the security server on a cache miss to obtain 900 * a new decision and add it to the cache. Audit the granting or denial of 901 * permissions in accordance with the policy. Return %0 if all @requested 902 * permissions are granted, -%EACCES if any permissions are denied, or 903 * another -errno upon other errors. 904 */ 905 int avc_has_perm(u32 ssid, u32 tsid, u16 tclass, 906 u32 requested, struct avc_audit_data *auditdata) 907 { 908 struct av_decision avd; 909 int rc; 910 911 rc = avc_has_perm_noaudit(ssid, tsid, tclass, requested, &avd); 912 avc_audit(ssid, tsid, tclass, requested, &avd, rc, auditdata); 913 return rc; 914 } 915