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 av_perm_to_string[] = {
  36 #define S_(c, v, s) { c, v, s },
  37 #include "av_perm_to_string.h"
  38 #undef S_
  39 };
  40
  41 static const char *class_to_string[] = {
  42 #define S_(s) s,
  43 #include "class_to_string.h"
  44 #undef S_
  45 };
  46
  47 #define TB_(s) static const char *s[] = {
  48 #define TE_(s) };
  49 #define S_(s) s,
  50 #include "common_perm_to_string.h"
  51 #undef TB_
  52 #undef TE_
  53 #undef S_
  54
  55 static const struct av_inherit av_inherit[] = {
  56 #define S_(c, i, b) {   .tclass = c,\
  57                         .common_pts = common_##i##_perm_to_string,\
  58                         .common_base =  b },
  59 #include "av_inherit.h"
  60 #undef S_
  61 };
  62
  63 const struct selinux_class_perm selinux_class_perm = {
  64         .av_perm_to_string = av_perm_to_string,
  65         .av_pts_len = ARRAY_SIZE(av_perm_to_string),
  66         .class_to_string = class_to_string,
  67         .cts_len = ARRAY_SIZE(class_to_string),
  68         .av_inherit = av_inherit,
  69         .av_inherit_len = ARRAY_SIZE(av_inherit)
  70 };
  71
  72 #define AVC_CACHE_SLOTS                 512
  73 #define AVC_DEF_CACHE_THRESHOLD         512
  74 #define AVC_CACHE_RECLAIM               16
  75
  76 #ifdef CONFIG_SECURITY_SELINUX_AVC_STATS
  77 #define avc_cache_stats_incr(field)                             \
  78 do {                                                            \
  79         per_cpu(avc_cache_stats, get_cpu()).field++;            \
  80         put_cpu();                                              \
  81 } while (0)
  82 #else
  83 #define avc_cache_stats_incr(field)     do {} while (0)
  84 #endif
  85
  86 struct avc_entry {
  87         u32                     ssid;
  88         u32                     tsid;
  89         u16                     tclass;
  90         struct av_decision      avd;
  91 };
  92
  93 struct avc_node {
  94         struct avc_entry        ae;
  95         struct list_head        list; /* anchored in avc_cache->slots[i] */
  96         struct rcu_head         rhead;
  97 };
  98
  99 struct avc_cache {
 100         struct list_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
 107 struct 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 */
 120 unsigned int avc_cache_threshold = AVC_DEF_CACHE_THRESHOLD;
 121
 122 #ifdef CONFIG_SECURITY_SELINUX_AVC_STATS
 123 DEFINE_PER_CPU(struct avc_cache_stats, avc_cache_stats) = { 0 };
 124 #endif
 125
 126 static struct avc_cache avc_cache;
 127 static struct avc_callback_node *avc_callbacks;
 128 static struct kmem_cache *avc_node_cachep;
 129
 130 static 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  */
 140 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  */
 200 static 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  */
 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);
 244
 245         audit_log(current->audit_context, GFP_KERNEL, 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         struct list_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 (!list_empty(head)) {
 261                         slots_used++;
 262                         chain_len = 0;
 263                         list_for_each_entry_rcu(node, head, list)
 264                                 chain_len++;
 265                         if (chain_len > max_chain_len)
 266                                 max_chain_len = chain_len;
 267                 }
 268         }
 269
 270         rcu_read_unlock();
 271
 272         return scnprintf(page, PAGE_SIZE, "entries: %d\nbuckets used: %d/%d\n"
 273                          "longest chain: %d\n",
 274                          atomic_read(&avc_cache.active_nodes),
 275                          slots_used, AVC_CACHE_SLOTS, max_chain_len);
 276 }
 277
 278 static void avc_node_free(struct rcu_head *rhead)
 279 {
 280         struct avc_node *node = container_of(rhead, struct avc_node, rhead);
 281         kmem_cache_free(avc_node_cachep, node);
 282         avc_cache_stats_incr(frees);
 283 }
 284
 285 static void avc_node_delete(struct avc_node *node)
 286 {
 287         list_del_rcu(&node->list);
 288         call_rcu(&node->rhead, avc_node_free);
 289         atomic_dec(&avc_cache.active_nodes);
 290 }
 291
 292 static void avc_node_kill(struct avc_node *node)
 293 {
 294         kmem_cache_free(avc_node_cachep, node);
 295         avc_cache_stats_incr(frees);
 296         atomic_dec(&avc_cache.active_nodes);
 297 }
 298
 299 static void avc_node_replace(struct avc_node *new, struct avc_node *old)
 300 {
 301         list_replace_rcu(&old->list, &new->list);
 302         call_rcu(&old->rhead, avc_node_free);
 303         atomic_dec(&avc_cache.active_nodes);
 304 }
 305
 306 static inline int avc_reclaim_node(void)
 307 {
 308         struct avc_node *node;
 309         int hvalue, try, ecx;
 310         unsigned long flags;
 311         struct list_head *head;
 312         spinlock_t *lock;
 313
 314         for (try = 0, ecx = 0; try < AVC_CACHE_SLOTS; try++) {
 315                 hvalue = atomic_inc_return(&avc_cache.lru_hint) & (AVC_CACHE_SLOTS - 1);
 316                 head = &avc_cache.slots[hvalue];
 317                 lock = &avc_cache.slots_lock[hvalue];
 318
 319                 if (!spin_trylock_irqsave(lock, flags))
 320                         continue;
 321
 322                 rcu_read_lock();
 323                 list_for_each_entry(node, head, list) {
 324                         avc_node_delete(node);
 325                         avc_cache_stats_incr(reclaims);
 326                         ecx++;
 327                         if (ecx >= AVC_CACHE_RECLAIM) {
 328                                 rcu_read_unlock();
 329                                 spin_unlock_irqrestore(lock, flags);
 330                                 goto out;
 331                         }
 332                 }
 333                 rcu_read_unlock();
 334                 spin_unlock_irqrestore(lock, flags);
 335         }
 336 out:
 337         return ecx;
 338 }
 339
 340 static struct avc_node *avc_alloc_node(void)
 341 {
 342         struct avc_node *node;
 343
 344         node = kmem_cache_zalloc(avc_node_cachep, GFP_ATOMIC);
 345         if (!node)
 346                 goto out;
 347
 348         INIT_RCU_HEAD(&node->rhead);
 349         INIT_LIST_HEAD(&node->list);
 350         avc_cache_stats_incr(allocations);
 351
 352         if (atomic_inc_return(&avc_cache.active_nodes) > avc_cache_threshold)
 353                 avc_reclaim_node();
 354
 355 out:
 356         return node;
 357 }
 358
 359 static void avc_node_populate(struct avc_node *node, u32 ssid, u32 tsid, u16 tclass, struct av_decision *avd)
 360 {
 361         node->ae.ssid = ssid;
 362         node->ae.tsid = tsid;
 363         node->ae.tclass = tclass;
 364         memcpy(&node->ae.avd, avd, sizeof(node->ae.avd));
 365 }
 366
 367 static inline struct avc_node *avc_search_node(u32 ssid, u32 tsid, u16 tclass)
 368 {
 369         struct avc_node *node, *ret = NULL;
 370         int hvalue;
 371         struct list_head *head;
 372
 373         hvalue = avc_hash(ssid, tsid, tclass);
 374         head = &avc_cache.slots[hvalue];
 375         list_for_each_entry_rcu(node, head, list) {
 376                 if (ssid == node->ae.ssid &&
 377                     tclass == node->ae.tclass &&
 378                     tsid == node->ae.tsid) {
 379                         ret = node;
 380                         break;
 381                 }
 382         }
 383
 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  *
 393  * Look up an AVC entry that is valid for the
 394  * (@ssid, @tsid), interpreting the permissions
 395  * based on @tclass.  If a valid AVC entry exists,
 396  * then this function return the avc_node.
 397  * Otherwise, this function returns NULL.
 398  */
 399 static struct avc_node *avc_lookup(u32 ssid, u32 tsid, u16 tclass)
 400 {
 401         struct avc_node *node;
 402
 403         avc_cache_stats_incr(lookups);
 404         node = avc_search_node(ssid, tsid, tclass);
 405
 406         if (node)
 407                 avc_cache_stats_incr(hits);
 408         else
 409                 avc_cache_stats_incr(misses);
 410
 411         return node;
 412 }
 413
 414 static int avc_latest_notif_update(int seqno, int is_insert)
 415 {
 416         int ret = 0;
 417         static DEFINE_SPINLOCK(notif_lock);
 418         unsigned long flag;
 419
 420         spin_lock_irqsave(&notif_lock, flag);
 421         if (is_insert) {
 422                 if (seqno < avc_cache.latest_notif) {
 423                         printk(KERN_WARNING "SELinux: avc:  seqno %d < latest_notif %d\n",
 424                                seqno, avc_cache.latest_notif);
 425                         ret = -EAGAIN;
 426                 }
 427         } else {
 428                 if (seqno > avc_cache.latest_notif)
 429                         avc_cache.latest_notif = seqno;
 430         }
 431         spin_unlock_irqrestore(&notif_lock, flag);
 432
 433         return ret;
 434 }
 435
 436 /**
 437  * avc_insert - Insert an AVC entry.
 438  * @ssid: source security identifier
 439  * @tsid: target security identifier
 440  * @tclass: target security class
 441  * @avd: resulting av decision
 442  *
 443  * Insert an AVC entry for the SID pair
 444  * (@ssid, @tsid) and class @tclass.
 445  * The access vectors and the sequence number are
 446  * normally provided by the security server in
 447  * response to a security_compute_av() call.  If the
 448  * sequence number @avd->seqno is not less than the latest
 449  * revocation notification, then the function copies
 450  * the access vectors into a cache entry, returns
 451  * avc_node inserted. Otherwise, this function returns NULL.
 452  */
 453 static struct avc_node *avc_insert(u32 ssid, u32 tsid, u16 tclass, struct av_decision *avd)
 454 {
 455         struct avc_node *pos, *node = NULL;
 456         int hvalue;
 457         unsigned long flag;
 458
 459         if (avc_latest_notif_update(avd->seqno, 1))
 460                 goto out;
 461
 462         node = avc_alloc_node();
 463         if (node) {
 464                 struct list_head *head;
 465                 spinlock_t *lock;
 466
 467                 hvalue = avc_hash(ssid, tsid, tclass);
 468                 avc_node_populate(node, ssid, tsid, tclass, avd);
 469
 470                 head = &avc_cache.slots[hvalue];
 471                 lock = &avc_cache.slots_lock[hvalue];
 472
 473                 spin_lock_irqsave(lock, flag);
 474                 list_for_each_entry(pos, head, list) {
 475                         if (pos->ae.ssid == ssid &&
 476                             pos->ae.tsid == tsid &&
 477                             pos->ae.tclass == tclass) {
 478                                 avc_node_replace(node, pos);
 479                                 goto found;
 480                         }
 481                 }
 482                 list_add_rcu(&node->list, head);
 483 found:
 484                 spin_unlock_irqrestore(lock, flag);
 485         }
 486 out:
 487         return node;
 488 }
 489
 490 static inline void avc_print_ipv6_addr(struct audit_buffer *ab,
 491                                        struct in6_addr *addr, __be16 port,
 492                                        char *name1, char *name2)
 493 {
 494         if (!ipv6_addr_any(addr))
 495                 audit_log_format(ab, " %s=%pI6", name1, addr);
 496         if (port)
 497                 audit_log_format(ab, " %s=%d", name2, ntohs(port));
 498 }
 499
 500 static inline void avc_print_ipv4_addr(struct audit_buffer *ab, __be32 addr,
 501                                        __be16 port, char *name1, char *name2)
 502 {
 503         if (addr)
 504                 audit_log_format(ab, " %s=%pI4", name1, &addr);
 505         if (port)
 506                 audit_log_format(ab, " %s=%d", name2, ntohs(port));
 507 }
 508
 509 /**
 510  * avc_audit - Audit the granting or denial of permissions.
 511  * @ssid: source security identifier
 512  * @tsid: target security identifier
 513  * @tclass: target security class
 514  * @requested: requested permissions
 515  * @avd: access vector decisions
 516  * @result: result from avc_has_perm_noaudit
 517  * @a:  auxiliary audit data
 518  *
 519  * Audit the granting or denial of permissions in accordance
 520  * with the policy.  This function is typically called by
 521  * avc_has_perm() after a permission check, but can also be
 522  * called directly by callers who use avc_has_perm_noaudit()
 523  * in order to separate the permission check from the auditing.
 524  * For example, this separation is useful when the permission check must
 525  * be performed under a lock, to allow the lock to be released
 526  * before calling the auditing code.
 527  */
 528 void avc_audit(u32 ssid, u32 tsid,
 529                u16 tclass, u32 requested,
 530                struct av_decision *avd, int result, struct avc_audit_data *a)
 531 {
 532         struct task_struct *tsk = current;
 533         struct inode *inode = NULL;
 534         u32 denied, audited;
 535         struct audit_buffer *ab;
 536
 537         denied = requested & ~avd->allowed;
 538         if (denied) {
 539                 audited = denied;
 540                 if (!(audited & avd->auditdeny))
 541                         return;
 542         } else if (result) {
 543                 audited = denied = requested;
 544         } else {
 545                 audited = requested;
 546                 if (!(audited & avd->auditallow))
 547                         return;
 548         }
 549
 550         ab = audit_log_start(current->audit_context, GFP_ATOMIC, AUDIT_AVC);
 551         if (!ab)
 552                 return;         /* audit_panic has been called */
 553         audit_log_format(ab, "avc:  %s ", denied ? "denied" : "granted");
 554         avc_dump_av(ab, tclass, audited);
 555         audit_log_format(ab, " for ");
 556         if (a && a->tsk)
 557                 tsk = a->tsk;
 558         if (tsk && tsk->pid) {
 559                 audit_log_format(ab, " pid=%d comm=", tsk->pid);
 560                 audit_log_untrustedstring(ab, tsk->comm);
 561         }
 562         if (a) {
 563                 switch (a->type) {
 564                 case AVC_AUDIT_DATA_IPC:
 565                         audit_log_format(ab, " key=%d", a->u.ipc_id);
 566                         break;
 567                 case AVC_AUDIT_DATA_CAP:
 568                         audit_log_format(ab, " capability=%d", a->u.cap);
 569                         break;
 570                 case AVC_AUDIT_DATA_FS:
 571                         if (a->u.fs.path.dentry) {
 572                                 struct dentry *dentry = a->u.fs.path.dentry;
 573                                 if (a->u.fs.path.mnt) {
 574                                         audit_log_d_path(ab, "path=",
 575                                                          &a->u.fs.path);
 576                                 } else {
 577                                         audit_log_format(ab, " name=");
 578                                         audit_log_untrustedstring(ab, dentry->d_name.name);
 579                                 }
 580                                 inode = dentry->d_inode;
 581                         } else if (a->u.fs.inode) {
 582                                 struct dentry *dentry;
 583                                 inode = a->u.fs.inode;
 584                                 dentry = d_find_alias(inode);
 585                                 if (dentry) {
 586                                         audit_log_format(ab, " name=");
 587                                         audit_log_untrustedstring(ab, dentry->d_name.name);
 588                                         dput(dentry);
 589                                 }
 590                         }
 591                         if (inode)
 592                                 audit_log_format(ab, " dev=%s ino=%lu",
 593                                                  inode->i_sb->s_id,
 594                                                  inode->i_ino);
 595                         break;
 596                 case AVC_AUDIT_DATA_NET:
 597                         if (a->u.net.sk) {
 598                                 struct sock *sk = a->u.net.sk;
 599                                 struct unix_sock *u;
 600                                 int len = 0;
 601                                 char *p = NULL;
 602
 603                                 switch (sk->sk_family) {
 604                                 case AF_INET: {
 605                                         struct inet_sock *inet = inet_sk(sk);
 606
 607                                         avc_print_ipv4_addr(ab, inet->rcv_saddr,
 608                                                             inet->sport,
 609                                                             "laddr", "lport");
 610                                         avc_print_ipv4_addr(ab, inet->daddr,
 611                                                             inet->dport,
 612                                                             "faddr", "fport");
 613                                         break;
 614                                 }
 615                                 case AF_INET6: {
 616                                         struct inet_sock *inet = inet_sk(sk);
 617                                         struct ipv6_pinfo *inet6 = inet6_sk(sk);
 618
 619                                         avc_print_ipv6_addr(ab, &inet6->rcv_saddr,
 620                                                             inet->sport,
 621                                                             "laddr", "lport");
 622                                         avc_print_ipv6_addr(ab, &inet6->daddr,
 623                                                             inet->dport,
 624                                                             "faddr", "fport");
 625                                         break;
 626                                 }
 627                                 case AF_UNIX:
 628                                         u = unix_sk(sk);
 629                                         if (u->dentry) {
 630                                                 struct path path = {
 631                                                         .dentry = u->dentry,
 632                                                         .mnt = u->mnt
 633                                                 };
 634                                                 audit_log_d_path(ab, "path=",
 635                                                                  &path);
 636                                                 break;
 637                                         }
 638                                         if (!u->addr)
 639                                                 break;
 640                                         len = u->addr->len-sizeof(short);
 641                                         p = &u->addr->name->sun_path[0];
 642                                         audit_log_format(ab, " path=");
 643                                         if (*p)
 644                                                 audit_log_untrustedstring(ab, p);
 645                                         else
 646                                                 audit_log_n_hex(ab, p, len);
 647                                         break;
 648                                 }
 649                         }
 650
 651                         switch (a->u.net.family) {
 652                         case AF_INET:
 653                                 avc_print_ipv4_addr(ab, a->u.net.v4info.saddr,
 654                                                     a->u.net.sport,
 655                                                     "saddr", "src");
 656                                 avc_print_ipv4_addr(ab, a->u.net.v4info.daddr,
 657                                                     a->u.net.dport,
 658                                                     "daddr", "dest");
 659                                 break;
 660                         case AF_INET6:
 661                                 avc_print_ipv6_addr(ab, &a->u.net.v6info.saddr,
 662                                                     a->u.net.sport,
 663                                                     "saddr", "src");
 664                                 avc_print_ipv6_addr(ab, &a->u.net.v6info.daddr,
 665                                                     a->u.net.dport,
 666                                                     "daddr", "dest");
 667                                 break;
 668                         }
 669                         if (a->u.net.netif > 0) {
 670                                 struct net_device *dev;
 671
 672                                 /* NOTE: we always use init's namespace */
 673                                 dev = dev_get_by_index(&init_net,
 674                                                        a->u.net.netif);
 675                                 if (dev) {
 676                                         audit_log_format(ab, " netif=%s",
 677                                                          dev->name);
 678                                         dev_put(dev);
 679                                 }
 680                         }
 681                         break;
 682                 }
 683         }
 684         audit_log_format(ab, " ");
 685         avc_dump_query(ab, ssid, tsid, tclass);
 686         audit_log_end(ab);
 687 }
 688
 689 /**
 690  * avc_add_callback - Register a callback for security events.
 691  * @callback: callback function
 692  * @events: security events
 693  * @ssid: source security identifier or %SECSID_WILD
 694  * @tsid: target security identifier or %SECSID_WILD
 695  * @tclass: target security class
 696  * @perms: permissions
 697  *
 698  * Register a callback function for events in the set @events
 699  * related to the SID pair (@ssid, @tsid) and
 700  * and the permissions @perms, interpreting
 701  * @perms based on @tclass.  Returns %0 on success or
 702  * -%ENOMEM if insufficient memory exists to add the callback.
 703  */
 704 int avc_add_callback(int (*callback)(u32 event, u32 ssid, u32 tsid,
 705                                      u16 tclass, u32 perms,
 706                                      u32 *out_retained),
 707                      u32 events, u32 ssid, u32 tsid,
 708                      u16 tclass, u32 perms)
 709 {
 710         struct avc_callback_node *c;
 711         int rc = 0;
 712
 713         c = kmalloc(sizeof(*c), GFP_ATOMIC);
 714         if (!c) {
 715                 rc = -ENOMEM;
 716                 goto out;
 717         }
 718
 719         c->callback = callback;
 720         c->events = events;
 721         c->ssid = ssid;
 722         c->tsid = tsid;
 723         c->perms = perms;
 724         c->next = avc_callbacks;
 725         avc_callbacks = c;
 726 out:
 727         return rc;
 728 }
 729
 730 static inline int avc_sidcmp(u32 x, u32 y)
 731 {
 732         return (x == y || x == SECSID_WILD || y == SECSID_WILD);
 733 }
 734
 735 /**
 736  * avc_update_node Update an AVC entry
 737  * @event : Updating event
 738  * @perms : Permission mask bits
 739  * @ssid,@tsid,@tclass : identifier of an AVC entry
 740  * @seqno : sequence number when decision was made
 741  *
 742  * if a valid AVC entry doesn't exist,this function returns -ENOENT.
 743  * if kmalloc() called internal returns NULL, this function returns -ENOMEM.
 744  * otherwise, this function update the AVC entry. The original AVC-entry object
 745  * will release later by RCU.
 746  */
 747 static int avc_update_node(u32 event, u32 perms, u32 ssid, u32 tsid, u16 tclass,
 748                            u32 seqno)
 749 {
 750         int hvalue, rc = 0;
 751         unsigned long flag;
 752         struct avc_node *pos, *node, *orig = NULL;
 753         struct list_head *head;
 754         spinlock_t *lock;
 755
 756         node = avc_alloc_node();
 757         if (!node) {
 758                 rc = -ENOMEM;
 759                 goto out;
 760         }
 761
 762         /* Lock the target slot */
 763         hvalue = avc_hash(ssid, tsid, tclass);
 764
 765         head = &avc_cache.slots[hvalue];
 766         lock = &avc_cache.slots_lock[hvalue];
 767
 768         spin_lock_irqsave(lock, flag);
 769
 770         list_for_each_entry(pos, head, list) {
 771                 if (ssid == pos->ae.ssid &&
 772                     tsid == pos->ae.tsid &&
 773                     tclass == pos->ae.tclass &&
 774                     seqno == pos->ae.avd.seqno){
 775                         orig = pos;
 776                         break;
 777                 }
 778         }
 779
 780         if (!orig) {
 781                 rc = -ENOENT;
 782                 avc_node_kill(node);
 783                 goto out_unlock;
 784         }
 785
 786         /*
 787          * Copy and replace original node.
 788          */
 789
 790         avc_node_populate(node, ssid, tsid, tclass, &orig->ae.avd);
 791
 792         switch (event) {
 793         case AVC_CALLBACK_GRANT:
 794                 node->ae.avd.allowed |= perms;
 795                 break;
 796         case AVC_CALLBACK_TRY_REVOKE:
 797         case AVC_CALLBACK_REVOKE:
 798                 node->ae.avd.allowed &= ~perms;
 799                 break;
 800         case AVC_CALLBACK_AUDITALLOW_ENABLE:
 801                 node->ae.avd.auditallow |= perms;
 802                 break;
 803         case AVC_CALLBACK_AUDITALLOW_DISABLE:
 804                 node->ae.avd.auditallow &= ~perms;
 805                 break;
 806         case AVC_CALLBACK_AUDITDENY_ENABLE:
 807                 node->ae.avd.auditdeny |= perms;
 808                 break;
 809         case AVC_CALLBACK_AUDITDENY_DISABLE:
 810                 node->ae.avd.auditdeny &= ~perms;
 811                 break;
 812         }
 813         avc_node_replace(node, orig);
 814 out_unlock:
 815         spin_unlock_irqrestore(lock, flag);
 816 out:
 817         return rc;
 818 }
 819
 820 /**
 821  * avc_ss_reset - Flush the cache and revalidate migrated permissions.
 822  * @seqno: policy sequence number
 823  */
 824 int avc_ss_reset(u32 seqno)
 825 {
 826         struct avc_callback_node *c;
 827         int i, rc = 0, tmprc;
 828         unsigned long flag;
 829         struct avc_node *node;
 830         struct list_head *head;
 831         spinlock_t *lock;
 832
 833         for (i = 0; i < AVC_CACHE_SLOTS; i++) {
 834                 head = &avc_cache.slots[i];
 835                 lock = &avc_cache.slots_lock[i];
 836
 837                 spin_lock_irqsave(lock, flag);
 838                 /*
 839                  * With preemptable RCU, the outer spinlock does not
 840                  * prevent RCU grace periods from ending.
 841                  */
 842                 rcu_read_lock();
 843                 list_for_each_entry(node, head, list)
 844                         avc_node_delete(node);
 845                 rcu_read_unlock();
 846                 spin_unlock_irqrestore(lock, flag);
 847         }
 848
 849         for (c = avc_callbacks; c; c = c->next) {
 850                 if (c->events & AVC_CALLBACK_RESET) {
 851                         tmprc = c->callback(AVC_CALLBACK_RESET,
 852                                             0, 0, 0, 0, NULL);
 853                         /* save the first error encountered for the return
 854                            value and continue processing the callbacks */
 855                         if (!rc)
 856                                 rc = tmprc;
 857                 }
 858         }
 859
 860         avc_latest_notif_update(seqno, 0);
 861         return rc;
 862 }
 863
 864 /**
 865  * avc_has_perm_noaudit - Check permissions but perform no auditing.
 866  * @ssid: source security identifier
 867  * @tsid: target security identifier
 868  * @tclass: target security class
 869  * @requested: requested permissions, interpreted based on @tclass
 870  * @flags:  AVC_STRICT or 0
 871  * @avd: access vector decisions
 872  *
 873  * Check the AVC to determine whether the @requested permissions are granted
 874  * for the SID pair (@ssid, @tsid), interpreting the permissions
 875  * based on @tclass, and call the security server on a cache miss to obtain
 876  * a new decision and add it to the cache.  Return a copy of the decisions
 877  * in @avd.  Return %0 if all @requested permissions are granted,
 878  * -%EACCES if any permissions are denied, or another -errno upon
 879  * other errors.  This function is typically called by avc_has_perm(),
 880  * but may also be called directly to separate permission checking from
 881  * auditing, e.g. in cases where a lock must be held for the check but
 882  * should be released for the auditing.
 883  */
 884 int avc_has_perm_noaudit(u32 ssid, u32 tsid,
 885                          u16 tclass, u32 requested,
 886                          unsigned flags,
 887                          struct av_decision *in_avd)
 888 {
 889         struct avc_node *node;
 890         struct av_decision avd_entry, *avd;
 891         int rc = 0;
 892         u32 denied;
 893
 894         BUG_ON(!requested);
 895
 896         rcu_read_lock();
 897
 898         node = avc_lookup(ssid, tsid, tclass);
 899         if (!node) {
 900                 rcu_read_unlock();
 901
 902                 if (in_avd)
 903                         avd = in_avd;
 904                 else
 905                         avd = &avd_entry;
 906
 907                 rc = security_compute_av(ssid, tsid, tclass, requested, avd);
 908                 if (rc)
 909                         goto out;
 910                 rcu_read_lock();
 911                 node = avc_insert(ssid, tsid, tclass, avd);
 912         } else {
 913                 if (in_avd)
 914                         memcpy(in_avd, &node->ae.avd, sizeof(*in_avd));
 915                 avd = &node->ae.avd;
 916         }
 917
 918         denied = requested & ~(avd->allowed);
 919
 920         if (denied) {
 921                 if (flags & AVC_STRICT)
 922                         rc = -EACCES;
 923                 else if (!selinux_enforcing || security_permissive_sid(ssid))
 924                         avc_update_node(AVC_CALLBACK_GRANT, requested, ssid,
 925                                         tsid, tclass, avd->seqno);
 926                 else
 927                         rc = -EACCES;
 928         }
 929
 930         rcu_read_unlock();
 931 out:
 932         return rc;
 933 }
 934
 935 /**
 936  * avc_has_perm - Check permissions and perform any appropriate auditing.
 937  * @ssid: source security identifier
 938  * @tsid: target security identifier
 939  * @tclass: target security class
 940  * @requested: requested permissions, interpreted based on @tclass
 941  * @auditdata: auxiliary audit data
 942  *
 943  * Check the AVC to determine whether the @requested permissions are granted
 944  * for the SID pair (@ssid, @tsid), interpreting the permissions
 945  * based on @tclass, and call the security server on a cache miss to obtain
 946  * a new decision and add it to the cache.  Audit the granting or denial of
 947  * permissions in accordance with the policy.  Return %0 if all @requested
 948  * permissions are granted, -%EACCES if any permissions are denied, or
 949  * another -errno upon other errors.
 950  */
 951 int avc_has_perm(u32 ssid, u32 tsid, u16 tclass,
 952                  u32 requested, struct avc_audit_data *auditdata)
 953 {
 954         struct av_decision avd;
 955         int rc;
 956
 957         rc = avc_has_perm_noaudit(ssid, tsid, tclass, requested, 0, &avd);
 958         avc_audit(ssid, tsid, tclass, requested, &avd, rc, auditdata);
 959         return rc;
 960 }
 961
 962 u32 avc_policy_seqno(void)
 963 {
 964         return avc_cache.latest_notif;
 965 }