security/selinux/avc.c

   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
  36 {
  37   u16 tclass;
  38   u32 value;
  39   const char *name;
  40 } av_perm_to_string[] = {
  41 #define S_(c, v, s) { c, v, s },
  42 #include "av_perm_to_string.h"
  43 #undef S_
  44 };
  45
  46 #ifdef CONFIG_AUDIT
  47 static const char *class_to_string[] = {
  48 #define S_(s) s,
  49 #include "class_to_string.h"
  50 #undef S_
  51 };
  52 #endif
  53
  54 #define TB_(s) static const char * s [] = {
  55 #define TE_(s) };
  56 #define S_(s) s,
  57 #include "common_perm_to_string.h"
  58 #undef TB_
  59 #undef TE_
  60 #undef S_
  61
  62 static const struct av_inherit
  63 {
  64     u16 tclass;
  65     const char **common_pts;
  66     u32 common_base;
  67 } av_inherit[] = {
  68 #define S_(c, i, b) { c, common_##i##_perm_to_string, b },
  69 #include "av_inherit.h"
  70 #undef S_
  71 };
  72
  73 #define AVC_CACHE_SLOTS                 512
  74 #define AVC_DEF_CACHE_THRESHOLD         512
  75 #define AVC_CACHE_RECLAIM               16
  76
  77 #ifdef CONFIG_SECURITY_SELINUX_AVC_STATS
  78 #define avc_cache_stats_incr(field)                             \
  79 do {                                                            \
  80         per_cpu(avc_cache_stats, get_cpu()).field++;            \
  81         put_cpu();                                              \
  82 } while (0)
  83 #else
  84 #define avc_cache_stats_incr(field)     do {} while (0)
  85 #endif
  86
  87 struct avc_entry {
  88         u32                     ssid;
  89         u32                     tsid;
  90         u16                     tclass;
  91         struct av_decision      avd;
  92         atomic_t                used;   /* used recently */
  93 };
  94
  95 struct avc_node {
  96         struct avc_entry        ae;
  97         struct list_head        list;
  98         struct rcu_head         rhead;
  99 };
 100
 101 struct avc_cache {
 102         struct list_head        slots[AVC_CACHE_SLOTS];
 103         spinlock_t              slots_lock[AVC_CACHE_SLOTS]; /* lock for writes */
 104         atomic_t                lru_hint;       /* LRU hint for reclaim scan */
 105         atomic_t                active_nodes;
 106         u32                     latest_notif;   /* latest revocation notification */
 107 };
 108
 109 struct avc_callback_node {
 110         int (*callback) (u32 event, u32 ssid, u32 tsid,
 111                          u16 tclass, u32 perms,
 112                          u32 *out_retained);
 113         u32 events;
 114         u32 ssid;
 115         u32 tsid;
 116         u16 tclass;
 117         u32 perms;
 118         struct avc_callback_node *next;
 119 };
 120
 121 /* Exported via selinufs */
 122 unsigned int avc_cache_threshold = AVC_DEF_CACHE_THRESHOLD;
 123
 124 #ifdef CONFIG_SECURITY_SELINUX_AVC_STATS
 125 DEFINE_PER_CPU(struct avc_cache_stats, avc_cache_stats) = { 0 };
 126 #endif
 127
 128 static struct avc_cache avc_cache;
 129 static struct avc_callback_node *avc_callbacks;
 130 static kmem_cache_t *avc_node_cachep;
 131
 132 static inline int avc_hash(u32 ssid, u32 tsid, u16 tclass)
 133 {
 134         return (ssid ^ (tsid<<2) ^ (tclass<<4)) & (AVC_CACHE_SLOTS - 1);
 135 }
 136
 137 /**
 138  * avc_dump_av - Display an access vector in human-readable form.
 139  * @tclass: target security class
 140  * @av: access vector
 141  */
 142 static void avc_dump_av(struct audit_buffer *ab, u16 tclass, u32 av)
 143 {
 144         const char **common_pts = NULL;
 145         u32 common_base = 0;
 146         int i, i2, perm;
 147
 148         if (av == 0) {
 149                 audit_log_format(ab, " null");
 150                 return;
 151         }
 152
 153         for (i = 0; i < ARRAY_SIZE(av_inherit); i++) {
 154                 if (av_inherit[i].tclass == tclass) {
 155                         common_pts = av_inherit[i].common_pts;
 156                         common_base = av_inherit[i].common_base;
 157                         break;
 158                 }
 159         }
 160
 161         audit_log_format(ab, " {");
 162         i = 0;
 163         perm = 1;
 164         while (perm < common_base) {
 165                 if (perm & av) {
 166                         audit_log_format(ab, " %s", common_pts[i]);
 167                         av &= ~perm;
 168                 }
 169                 i++;
 170                 perm <<= 1;
 171         }
 172
 173         while (i < sizeof(av) * 8) {
 174                 if (perm & av) {
 175                         for (i2 = 0; i2 < ARRAY_SIZE(av_perm_to_string); i2++) {
 176                                 if ((av_perm_to_string[i2].tclass == tclass) &&
 177                                     (av_perm_to_string[i2].value == perm))
 178                                         break;
 179                         }
 180                         if (i2 < ARRAY_SIZE(av_perm_to_string)) {
 181                                 audit_log_format(ab, " %s",
 182                                                  av_perm_to_string[i2].name);
 183                                 av &= ~perm;
 184                         }
 185                 }
 186                 i++;
 187                 perm <<= 1;
 188         }
 189
 190         if (av)
 191                 audit_log_format(ab, " 0x%x", av);
 192
 193         audit_log_format(ab, " }");
 194 }
 195
 196 /**
 197  * avc_dump_query - Display a SID pair and a class in human-readable form.
 198  * @ssid: source security identifier
 199  * @tsid: target security identifier
 200  * @tclass: target security class
 201  */
 202 static void avc_dump_query(struct audit_buffer *ab, u32 ssid, u32 tsid, u16 tclass)
 203 {
 204         int rc;
 205         char *scontext;
 206         u32 scontext_len;
 207
 208         rc = security_sid_to_context(ssid, &scontext, &scontext_len);
 209         if (rc)
 210                 audit_log_format(ab, "ssid=%d", ssid);
 211         else {
 212                 audit_log_format(ab, "scontext=%s", scontext);
 213                 kfree(scontext);
 214         }
 215
 216         rc = security_sid_to_context(tsid, &scontext, &scontext_len);
 217         if (rc)
 218                 audit_log_format(ab, " tsid=%d", tsid);
 219         else {
 220                 audit_log_format(ab, " tcontext=%s", scontext);
 221                 kfree(scontext);
 222         }
 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  */
 231 void __init avc_init(void)
 232 {
 233         int i;
 234
 235         for (i = 0; i < AVC_CACHE_SLOTS; i++) {
 236                 INIT_LIST_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, NULL);
 244
 245         audit_log(current->audit_context, AUDIT_KERNEL, "AVC INITIALIZED\n");
 246 }
 247
 248 int avc_get_hash_stats(char *page)
 249 {
 250         int i, chain_len, max_chain_len, slots_used;
 251         struct avc_node *node;
 252
 253         rcu_read_lock();
 254
 255         slots_used = 0;
 256         max_chain_len = 0;
 257         for (i = 0; i < AVC_CACHE_SLOTS; i++) {
 258                 if (!list_empty(&avc_cache.slots[i])) {
 259                         slots_used++;
 260                         chain_len = 0;
 261                         list_for_each_entry_rcu(node, &avc_cache.slots[i], list)
 262                                 chain_len++;
 263                         if (chain_len > max_chain_len)
 264                                 max_chain_len = chain_len;
 265                 }
 266         }
 267
 268         rcu_read_unlock();
 269
 270         return scnprintf(page, PAGE_SIZE, "entries: %d\nbuckets used: %d/%d\n"
 271                          "longest chain: %d\n",
 272                          atomic_read(&avc_cache.active_nodes),
 273                          slots_used, AVC_CACHE_SLOTS, max_chain_len);
 274 }
 275
 276 static void avc_node_free(struct rcu_head *rhead)
 277 {
 278         struct avc_node *node = container_of(rhead, struct avc_node, rhead);
 279         kmem_cache_free(avc_node_cachep, node);
 280         avc_cache_stats_incr(frees);
 281 }
 282
 283 static void avc_node_delete(struct avc_node *node)
 284 {
 285         list_del_rcu(&node->list);
 286         call_rcu(&node->rhead, avc_node_free);
 287         atomic_dec(&avc_cache.active_nodes);
 288 }
 289
 290 static void avc_node_kill(struct avc_node *node)
 291 {
 292         kmem_cache_free(avc_node_cachep, node);
 293         avc_cache_stats_incr(frees);
 294         atomic_dec(&avc_cache.active_nodes);
 295 }
 296
 297 static void avc_node_replace(struct avc_node *new, struct avc_node *old)
 298 {
 299         list_replace_rcu(&old->list, &new->list);
 300         call_rcu(&old->rhead, avc_node_free);
 301         atomic_dec(&avc_cache.active_nodes);
 302 }
 303
 304 static inline int avc_reclaim_node(void)
 305 {
 306         struct avc_node *node;
 307         int hvalue, try, ecx;
 308         unsigned long flags;
 309
 310         for (try = 0, ecx = 0; try < AVC_CACHE_SLOTS; try++ ) {
 311                 hvalue = atomic_inc_return(&avc_cache.lru_hint) & (AVC_CACHE_SLOTS - 1);
 312
 313                 if (!spin_trylock_irqsave(&avc_cache.slots_lock[hvalue], flags))
 314                         continue;
 315
 316                 list_for_each_entry(node, &avc_cache.slots[hvalue], list) {
 317                         if (atomic_dec_and_test(&node->ae.used)) {
 318                                 /* Recently Unused */
 319                                 avc_node_delete(node);
 320                                 avc_cache_stats_incr(reclaims);
 321                                 ecx++;
 322                                 if (ecx >= AVC_CACHE_RECLAIM) {
 323                                         spin_unlock_irqrestore(&avc_cache.slots_lock[hvalue], flags);
 324                                         goto out;
 325                                 }
 326                         }
 327                 }
 328                 spin_unlock_irqrestore(&avc_cache.slots_lock[hvalue], flags);
 329         }
 330 out:
 331         return ecx;
 332 }
 333
 334 static struct avc_node *avc_alloc_node(void)
 335 {
 336         struct avc_node *node;
 337
 338         node = kmem_cache_alloc(avc_node_cachep, SLAB_ATOMIC);
 339         if (!node)
 340                 goto out;
 341
 342         memset(node, 0, sizeof(*node));
 343         INIT_RCU_HEAD(&node->rhead);
 344         INIT_LIST_HEAD(&node->list);
 345         atomic_set(&node->ae.used, 1);
 346         avc_cache_stats_incr(allocations);
 347
 348         if (atomic_inc_return(&avc_cache.active_nodes) > avc_cache_threshold)
 349                 avc_reclaim_node();
 350
 351 out:
 352         return node;
 353 }
 354
 355 static void avc_node_populate(struct avc_node *node, u32 ssid, u32 tsid, u16 tclass, struct avc_entry *ae)
 356 {
 357         node->ae.ssid = ssid;
 358         node->ae.tsid = tsid;
 359         node->ae.tclass = tclass;
 360         memcpy(&node->ae.avd, &ae->avd, sizeof(node->ae.avd));
 361 }
 362
 363 static inline struct avc_node *avc_search_node(u32 ssid, u32 tsid, u16 tclass)
 364 {
 365         struct avc_node *node, *ret = NULL;
 366         int hvalue;
 367
 368         hvalue = avc_hash(ssid, tsid, tclass);
 369         list_for_each_entry_rcu(node, &avc_cache.slots[hvalue], list) {
 370                 if (ssid == node->ae.ssid &&
 371                     tclass == node->ae.tclass &&
 372                     tsid == node->ae.tsid) {
 373                         ret = node;
 374                         break;
 375                 }
 376         }
 377
 378         if (ret == NULL) {
 379                 /* cache miss */
 380                 goto out;
 381         }
 382
 383         /* cache hit */
 384         if (atomic_read(&ret->ae.used) != 1)
 385                 atomic_set(&ret->ae.used, 1);
 386 out:
 387         return ret;
 388 }
 389
 390 /**
 391  * avc_lookup - Look up an AVC entry.
 392  * @ssid: source security identifier
 393  * @tsid: target security identifier
 394  * @tclass: target security class
 395  * @requested: requested permissions, interpreted based on @tclass
 396  *
 397  * Look up an AVC entry that is valid for the
 398  * @requested permissions between the SID pair
 399  * (@ssid, @tsid), interpreting the permissions
 400  * based on @tclass.  If a valid AVC entry exists,
 401  * then this function return the avc_node.
 402  * Otherwise, this function returns NULL.
 403  */
 404 static struct avc_node *avc_lookup(u32 ssid, u32 tsid, u16 tclass, u32 requested)
 405 {
 406         struct avc_node *node;
 407
 408         avc_cache_stats_incr(lookups);
 409         node = avc_search_node(ssid, tsid, tclass);
 410
 411         if (node && ((node->ae.avd.decided & requested) == requested)) {
 412                 avc_cache_stats_incr(hits);
 413                 goto out;
 414         }
 415
 416         node = NULL;
 417         avc_cache_stats_incr(misses);
 418 out:
 419         return node;
 420 }
 421
 422 static int avc_latest_notif_update(int seqno, int is_insert)
 423 {
 424         int ret = 0;
 425         static DEFINE_SPINLOCK(notif_lock);
 426         unsigned long flag;
 427
 428         spin_lock_irqsave(&notif_lock, flag);
 429         if (is_insert) {
 430                 if (seqno < avc_cache.latest_notif) {
 431                         printk(KERN_WARNING "avc:  seqno %d < latest_notif %d\n",
 432                                seqno, avc_cache.latest_notif);
 433                         ret = -EAGAIN;
 434                 }
 435         } else {
 436                 if (seqno > avc_cache.latest_notif)
 437                         avc_cache.latest_notif = seqno;
 438         }
 439         spin_unlock_irqrestore(&notif_lock, flag);
 440
 441         return ret;
 442 }
 443
 444 /**
 445  * avc_insert - Insert an AVC entry.
 446  * @ssid: source security identifier
 447  * @tsid: target security identifier
 448  * @tclass: target security class
 449  * @ae: AVC entry
 450  *
 451  * Insert an AVC entry for the SID pair
 452  * (@ssid, @tsid) and class @tclass.
 453  * The access vectors and the sequence number are
 454  * normally provided by the security server in
 455  * response to a security_compute_av() call.  If the
 456  * sequence number @ae->avd.seqno is not less than the latest
 457  * revocation notification, then the function copies
 458  * the access vectors into a cache entry, returns
 459  * avc_node inserted. Otherwise, this function returns NULL.
 460  */
 461 static struct avc_node *avc_insert(u32 ssid, u32 tsid, u16 tclass, struct avc_entry *ae)
 462 {
 463         struct avc_node *pos, *node = NULL;
 464         int hvalue;
 465         unsigned long flag;
 466
 467         if (avc_latest_notif_update(ae->avd.seqno, 1))
 468                 goto out;
 469
 470         node = avc_alloc_node();
 471         if (node) {
 472                 hvalue = avc_hash(ssid, tsid, tclass);
 473                 avc_node_populate(node, ssid, tsid, tclass, ae);
 474
 475                 spin_lock_irqsave(&avc_cache.slots_lock[hvalue], flag);
 476                 list_for_each_entry(pos, &avc_cache.slots[hvalue], list) {
 477                         if (pos->ae.ssid == ssid &&
 478                             pos->ae.tsid == tsid &&
 479                             pos->ae.tclass == tclass) {
 480                                 avc_node_replace(node, pos);
 481                                 goto found;
 482                         }
 483                 }
 484                 list_add_rcu(&node->list, &avc_cache.slots[hvalue]);
 485 found:
 486                 spin_unlock_irqrestore(&avc_cache.slots_lock[hvalue], flag);
 487         }
 488 out:
 489         return node;
 490 }
 491
 492 static inline void avc_print_ipv6_addr(struct audit_buffer *ab,
 493                                        struct in6_addr *addr, u16 port,
 494                                        char *name1, char *name2)
 495 {
 496         if (!ipv6_addr_any(addr))
 497                 audit_log_format(ab, " %s=%04x:%04x:%04x:%04x:%04x:"
 498                                  "%04x:%04x:%04x", name1, NIP6(*addr));
 499         if (port)
 500                 audit_log_format(ab, " %s=%d", name2, ntohs(port));
 501 }
 502
 503 static inline void avc_print_ipv4_addr(struct audit_buffer *ab, u32 addr,
 504                                        u16 port, char *name1, char *name2)
 505 {
 506         if (addr)
 507                 audit_log_format(ab, " %s=%d.%d.%d.%d", name1, NIPQUAD(addr));
 508         if (port)
 509                 audit_log_format(ab, " %s=%d", name2, ntohs(port));
 510 }
 511
 512 /**
 513  * avc_audit - Audit the granting or denial of permissions.
 514  * @ssid: source security identifier
 515  * @tsid: target security identifier
 516  * @tclass: target security class
 517  * @requested: requested permissions
 518  * @avd: access vector decisions
 519  * @result: result from avc_has_perm_noaudit
 520  * @a:  auxiliary audit data
 521  *
 522  * Audit the granting or denial of permissions in accordance
 523  * with the policy.  This function is typically called by
 524  * avc_has_perm() after a permission check, but can also be
 525  * called directly by callers who use avc_has_perm_noaudit()
 526  * in order to separate the permission check from the auditing.
 527  * For example, this separation is useful when the permission check must
 528  * be performed under a lock, to allow the lock to be released
 529  * before calling the auditing code.
 530  */
 531 void avc_audit(u32 ssid, u32 tsid,
 532                u16 tclass, u32 requested,
 533                struct av_decision *avd, int result, struct avc_audit_data *a)
 534 {
 535         struct task_struct *tsk = current;
 536         struct inode *inode = NULL;
 537         u32 denied, audited;
 538         struct audit_buffer *ab;
 539
 540         denied = requested & ~avd->allowed;
 541         if (denied) {
 542                 audited = denied;
 543                 if (!(audited & avd->auditdeny))
 544                         return;
 545         } else if (result) {
 546                 audited = denied = requested;
 547         } else {
 548                 audited = requested;
 549                 if (!(audited & avd->auditallow))
 550                         return;
 551         }
 552
 553         ab = audit_log_start(current->audit_context, AUDIT_AVC);
 554         if (!ab)
 555                 return;         /* audit_panic has been called */
 556         audit_log_format(ab, "avc:  %s ", denied ? "denied" : "granted");
 557         avc_dump_av(ab, tclass,audited);
 558         audit_log_format(ab, " for ");
 559         if (a && a->tsk)
 560                 tsk = a->tsk;
 561         if (a->tsk && a->tsk->pid) {
 562                 audit_log_format(ab, " pid=%d comm=", tsk->pid);
 563                 audit_log_untrustedstring(ab, tsk->comm);
 564         }
 565         if (a) {
 566                 switch (a->type) {
 567                 case AVC_AUDIT_DATA_IPC:
 568                         audit_log_format(ab, " key=%d", a->u.ipc_id);
 569                         break;
 570                 case AVC_AUDIT_DATA_CAP:
 571                         audit_log_format(ab, " capability=%d", a->u.cap);
 572                         break;
 573                 case AVC_AUDIT_DATA_FS:
 574                         if (a->u.fs.dentry) {
 575                                 struct dentry *dentry = a->u.fs.dentry;
 576                                 if (a->u.fs.mnt) {
 577                                         audit_log_d_path(ab, "path=", dentry,
 578                                                         a->u.fs.mnt);
 579                                 } else {
 580                                         audit_log_format(ab, " name=%s",
 581                                                          dentry->d_name.name);
 582                                 }
 583                                 inode = dentry->d_inode;
 584                         } else if (a->u.fs.inode) {
 585                                 struct dentry *dentry;
 586                                 inode = a->u.fs.inode;
 587                                 dentry = d_find_alias(inode);
 588                                 if (dentry) {
 589                                         audit_log_format(ab, " name=%s",
 590                                                          dentry->d_name.name);
 591                                         dput(dentry);
 592                                 }
 593                         }
 594                         if (inode)
 595                                 audit_log_format(ab, " dev=%s ino=%ld",
 596                                                  inode->i_sb->s_id,
 597                                                  inode->i_ino);
 598                         break;
 599                 case AVC_AUDIT_DATA_NET:
 600                         if (a->u.net.sk) {
 601                                 struct sock *sk = a->u.net.sk;
 602                                 struct unix_sock *u;
 603                                 int len = 0;
 604                                 char *p = NULL;
 605
 606                                 switch (sk->sk_family) {
 607                                 case AF_INET: {
 608                                         struct inet_sock *inet = inet_sk(sk);
 609
 610                                         avc_print_ipv4_addr(ab, inet->rcv_saddr,
 611                                                             inet->sport,
 612                                                             "laddr", "lport");
 613                                         avc_print_ipv4_addr(ab, inet->daddr,
 614                                                             inet->dport,
 615                                                             "faddr", "fport");
 616                                         break;
 617                                 }
 618                                 case AF_INET6: {
 619                                         struct inet_sock *inet = inet_sk(sk);
 620                                         struct ipv6_pinfo *inet6 = inet6_sk(sk);
 621
 622                                         avc_print_ipv6_addr(ab, &inet6->rcv_saddr,
 623                                                             inet->sport,
 624                                                             "laddr", "lport");
 625                                         avc_print_ipv6_addr(ab, &inet6->daddr,
 626                                                             inet->dport,
 627                                                             "faddr", "fport");
 628                                         break;
 629                                 }
 630                                 case AF_UNIX:
 631                                         u = unix_sk(sk);
 632                                         if (u->dentry) {
 633                                                 audit_log_d_path(ab, "path=",
 634                                                         u->dentry, u->mnt);
 635                                                 break;
 636                                         }
 637                                         if (!u->addr)
 638                                                 break;
 639                                         len = u->addr->len-sizeof(short);
 640                                         p = &u->addr->name->sun_path[0];
 641                                         if (*p)
 642                                                 audit_log_format(ab,
 643                                                         "path=%*.*s", len,
 644                                                         len, p);
 645                                         else
 646                                                 audit_log_format(ab,
 647                                                         "path=@%*.*s", len-1,
 648                                                         len-1, p+1);
 649                                         break;
 650                                 }
 651                         }
 652
 653                         switch (a->u.net.family) {
 654                         case AF_INET:
 655                                 avc_print_ipv4_addr(ab, a->u.net.v4info.saddr,
 656                                                     a->u.net.sport,
 657                                                     "saddr", "src");
 658                                 avc_print_ipv4_addr(ab, a->u.net.v4info.daddr,
 659                                                     a->u.net.dport,
 660                                                     "daddr", "dest");
 661                                 break;
 662                         case AF_INET6:
 663                                 avc_print_ipv6_addr(ab, &a->u.net.v6info.saddr,
 664                                                     a->u.net.sport,
 665                                                     "saddr", "src");
 666                                 avc_print_ipv6_addr(ab, &a->u.net.v6info.daddr,
 667                                                     a->u.net.dport,
 668                                                     "daddr", "dest");
 669                                 break;
 670                         }
 671                         if (a->u.net.netif)
 672                                 audit_log_format(ab, " netif=%s",
 673                                         a->u.net.netif);
 674                         break;
 675                 }
 676         }
 677         audit_log_format(ab, " ");
 678         avc_dump_query(ab, ssid, tsid, tclass);
 679         audit_log_end(ab);
 680 }
 681
 682 /**
 683  * avc_add_callback - Register a callback for security events.
 684  * @callback: callback function
 685  * @events: security events
 686  * @ssid: source security identifier or %SECSID_WILD
 687  * @tsid: target security identifier or %SECSID_WILD
 688  * @tclass: target security class
 689  * @perms: permissions
 690  *
 691  * Register a callback function for events in the set @events
 692  * related to the SID pair (@ssid, @tsid) and
 693  * and the permissions @perms, interpreting
 694  * @perms based on @tclass.  Returns %0 on success or
 695  * -%ENOMEM if insufficient memory exists to add the callback.
 696  */
 697 int avc_add_callback(int (*callback)(u32 event, u32 ssid, u32 tsid,
 698                                      u16 tclass, u32 perms,
 699                                      u32 *out_retained),
 700                      u32 events, u32 ssid, u32 tsid,
 701                      u16 tclass, u32 perms)
 702 {
 703         struct avc_callback_node *c;
 704         int rc = 0;
 705
 706         c = kmalloc(sizeof(*c), GFP_ATOMIC);
 707         if (!c) {
 708                 rc = -ENOMEM;
 709                 goto out;
 710         }
 711
 712         c->callback = callback;
 713         c->events = events;
 714         c->ssid = ssid;
 715         c->tsid = tsid;
 716         c->perms = perms;
 717         c->next = avc_callbacks;
 718         avc_callbacks = c;
 719 out:
 720         return rc;
 721 }
 722
 723 static inline int avc_sidcmp(u32 x, u32 y)
 724 {
 725         return (x == y || x == SECSID_WILD || y == SECSID_WILD);
 726 }
 727
 728 /**
 729  * avc_update_node Update an AVC entry
 730  * @event : Updating event
 731  * @perms : Permission mask bits
 732  * @ssid,@tsid,@tclass : identifier of an AVC entry
 733  *
 734  * if a valid AVC entry doesn't exist,this function returns -ENOENT.
 735  * if kmalloc() called internal returns NULL, this function returns -ENOMEM.
 736  * otherwise, this function update the AVC entry. The original AVC-entry object
 737  * will release later by RCU.
 738  */
 739 static int avc_update_node(u32 event, u32 perms, u32 ssid, u32 tsid, u16 tclass)
 740 {
 741         int hvalue, rc = 0;
 742         unsigned long flag;
 743         struct avc_node *pos, *node, *orig = NULL;
 744
 745         node = avc_alloc_node();
 746         if (!node) {
 747                 rc = -ENOMEM;
 748                 goto out;
 749         }
 750
 751         /* Lock the target slot */
 752         hvalue = avc_hash(ssid, tsid, tclass);
 753         spin_lock_irqsave(&avc_cache.slots_lock[hvalue], flag);
 754
 755         list_for_each_entry(pos, &avc_cache.slots[hvalue], list){
 756                 if ( ssid==pos->ae.ssid &&
 757                      tsid==pos->ae.tsid &&
 758                      tclass==pos->ae.tclass ){
 759                         orig = pos;
 760                         break;
 761                 }
 762         }
 763
 764         if (!orig) {
 765                 rc = -ENOENT;
 766                 avc_node_kill(node);
 767                 goto out_unlock;
 768         }
 769
 770         /*
 771          * Copy and replace original node.
 772          */
 773
 774         avc_node_populate(node, ssid, tsid, tclass, &orig->ae);
 775
 776         switch (event) {
 777         case AVC_CALLBACK_GRANT:
 778                 node->ae.avd.allowed |= perms;
 779                 break;
 780         case AVC_CALLBACK_TRY_REVOKE:
 781         case AVC_CALLBACK_REVOKE:
 782                 node->ae.avd.allowed &= ~perms;
 783                 break;
 784         case AVC_CALLBACK_AUDITALLOW_ENABLE:
 785                 node->ae.avd.auditallow |= perms;
 786                 break;
 787         case AVC_CALLBACK_AUDITALLOW_DISABLE:
 788                 node->ae.avd.auditallow &= ~perms;
 789                 break;
 790         case AVC_CALLBACK_AUDITDENY_ENABLE:
 791                 node->ae.avd.auditdeny |= perms;
 792                 break;
 793         case AVC_CALLBACK_AUDITDENY_DISABLE:
 794                 node->ae.avd.auditdeny &= ~perms;
 795                 break;
 796         }
 797         avc_node_replace(node, orig);
 798 out_unlock:
 799         spin_unlock_irqrestore(&avc_cache.slots_lock[hvalue], flag);
 800 out:
 801         return rc;
 802 }
 803
 804 /**
 805  * avc_ss_reset - Flush the cache and revalidate migrated permissions.
 806  * @seqno: policy sequence number
 807  */
 808 int avc_ss_reset(u32 seqno)
 809 {
 810         struct avc_callback_node *c;
 811         int i, rc = 0;
 812         unsigned long flag;
 813         struct avc_node *node;
 814
 815         for (i = 0; i < AVC_CACHE_SLOTS; i++) {
 816                 spin_lock_irqsave(&avc_cache.slots_lock[i], flag);
 817                 list_for_each_entry(node, &avc_cache.slots[i], list)
 818                         avc_node_delete(node);
 819                 spin_unlock_irqrestore(&avc_cache.slots_lock[i], flag);
 820         }
 821
 822         for (c = avc_callbacks; c; c = c->next) {
 823                 if (c->events & AVC_CALLBACK_RESET) {
 824                         rc = c->callback(AVC_CALLBACK_RESET,
 825                                          0, 0, 0, 0, NULL);
 826                         if (rc)
 827                                 goto out;
 828                 }
 829         }
 830
 831         avc_latest_notif_update(seqno, 0);
 832 out:
 833         return rc;
 834 }
 835
 836 /**
 837  * avc_has_perm_noaudit - Check permissions but perform no auditing.
 838  * @ssid: source security identifier
 839  * @tsid: target security identifier
 840  * @tclass: target security class
 841  * @requested: requested permissions, interpreted based on @tclass
 842  * @avd: access vector decisions
 843  *
 844  * Check the AVC to determine whether the @requested permissions are granted
 845  * for the SID pair (@ssid, @tsid), interpreting the permissions
 846  * based on @tclass, and call the security server on a cache miss to obtain
 847  * a new decision and add it to the cache.  Return a copy of the decisions
 848  * in @avd.  Return %0 if all @requested permissions are granted,
 849  * -%EACCES if any permissions are denied, or another -errno upon
 850  * other errors.  This function is typically called by avc_has_perm(),
 851  * but may also be called directly to separate permission checking from
 852  * auditing, e.g. in cases where a lock must be held for the check but
 853  * should be released for the auditing.
 854  */
 855 int avc_has_perm_noaudit(u32 ssid, u32 tsid,
 856                          u16 tclass, u32 requested,
 857                          struct av_decision *avd)
 858 {
 859         struct avc_node *node;
 860         struct avc_entry entry, *p_ae;
 861         int rc = 0;
 862         u32 denied;
 863
 864         rcu_read_lock();
 865
 866         node = avc_lookup(ssid, tsid, tclass, requested);
 867         if (!node) {
 868                 rcu_read_unlock();
 869                 rc = security_compute_av(ssid,tsid,tclass,requested,&entry.avd);
 870                 if (rc)
 871                         goto out;
 872                 rcu_read_lock();
 873                 node = avc_insert(ssid,tsid,tclass,&entry);
 874         }
 875
 876         p_ae = node ? &node->ae : &entry;
 877
 878         if (avd)
 879                 memcpy(avd, &p_ae->avd, sizeof(*avd));
 880
 881         denied = requested & ~(p_ae->avd.allowed);
 882
 883         if (!requested || denied) {
 884                 if (selinux_enforcing)
 885                         rc = -EACCES;
 886                 else
 887                         if (node)
 888                                 avc_update_node(AVC_CALLBACK_GRANT,requested,
 889                                                 ssid,tsid,tclass);
 890         }
 891
 892         rcu_read_unlock();
 893 out:
 894         return rc;
 895 }
 896
 897 /**
 898  * avc_has_perm - Check permissions and perform any appropriate auditing.
 899  * @ssid: source security identifier
 900  * @tsid: target security identifier
 901  * @tclass: target security class
 902  * @requested: requested permissions, interpreted based on @tclass
 903  * @auditdata: auxiliary audit data
 904  *
 905  * Check the AVC to determine whether the @requested permissions are granted
 906  * for the SID pair (@ssid, @tsid), interpreting the permissions
 907  * based on @tclass, and call the security server on a cache miss to obtain
 908  * a new decision and add it to the cache.  Audit the granting or denial of
 909  * permissions in accordance with the policy.  Return %0 if all @requested
 910  * permissions are granted, -%EACCES if any permissions are denied, or
 911  * another -errno upon other errors.
 912  */
 913 int avc_has_perm(u32 ssid, u32 tsid, u16 tclass,
 914                  u32 requested, struct avc_audit_data *auditdata)
 915 {
 916         struct av_decision avd;
 917         int rc;
 918
 919         rc = avc_has_perm_noaudit(ssid, tsid, tclass, requested, &avd);
 920         avc_audit(ssid, tsid, tclass, requested, &avd, rc, auditdata);
 921         return rc;
 922 }