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) { c, common_##i##_perm_to_string, b },
  57 #include "av_inherit.h"
  58 #undef S_
  59 };
  60
  61 const struct selinux_class_perm selinux_class_perm = {
  62         av_perm_to_string,
  63         ARRAY_SIZE(av_perm_to_string),
  64         class_to_string,
  65         ARRAY_SIZE(class_to_string),
  66         av_inherit,
  67         ARRAY_SIZE(av_inherit)
  68 };
  69
  70 #define AVC_CACHE_SLOTS                 512
  71 #define AVC_DEF_CACHE_THRESHOLD         512
  72 #define AVC_CACHE_RECLAIM               16
  73
  74 #ifdef CONFIG_SECURITY_SELINUX_AVC_STATS
  75 #define avc_cache_stats_incr(field)                             \
  76 do {                                                            \
  77         per_cpu(avc_cache_stats, get_cpu()).field++;            \
  78         put_cpu();                                              \
  79 } while (0)
  80 #else
  81 #define avc_cache_stats_incr(field)     do {} while (0)
  82 #endif
  83
  84 struct avc_entry {
  85         u32                     ssid;
  86         u32                     tsid;
  87         u16                     tclass;
  88         struct av_decision      avd;
  89         atomic_t                used;   /* used recently */
  90 };
  91
  92 struct avc_node {
  93         struct avc_entry        ae;
  94         struct list_head        list;
  95         struct rcu_head         rhead;
  96 };
  97
  98 struct avc_cache {
  99         struct list_head        slots[AVC_CACHE_SLOTS];
 100         spinlock_t              slots_lock[AVC_CACHE_SLOTS]; /* lock for writes */
 101         atomic_t                lru_hint;       /* LRU hint for reclaim scan */
 102         atomic_t                active_nodes;
 103         u32                     latest_notif;   /* latest revocation notification */
 104 };
 105
 106 struct avc_callback_node {
 107         int (*callback) (u32 event, u32 ssid, u32 tsid,
 108                          u16 tclass, u32 perms,
 109                          u32 *out_retained);
 110         u32 events;
 111         u32 ssid;
 112         u32 tsid;
 113         u16 tclass;
 114         u32 perms;
 115         struct avc_callback_node *next;
 116 };
 117
 118 /* Exported via selinufs */
 119 unsigned int avc_cache_threshold = AVC_DEF_CACHE_THRESHOLD;
 120
 121 #ifdef CONFIG_SECURITY_SELINUX_AVC_STATS
 122 DEFINE_PER_CPU(struct avc_cache_stats, avc_cache_stats) = { 0 };
 123 #endif
 124
 125 static struct avc_cache avc_cache;
 126 static struct avc_callback_node *avc_callbacks;
 127 static struct kmem_cache *avc_node_cachep;
 128
 129 static inline int avc_hash(u32 ssid, u32 tsid, u16 tclass)
 130 {
 131         return (ssid ^ (tsid<<2) ^ (tclass<<4)) & (AVC_CACHE_SLOTS - 1);
 132 }
 133
 134 /**
 135  * avc_dump_av - Display an access vector in human-readable form.
 136  * @tclass: target security class
 137  * @av: access vector
 138  */
 139 static void avc_dump_av(struct audit_buffer *ab, u16 tclass, u32 av)
 140 {
 141         const char **common_pts = NULL;
 142         u32 common_base = 0;
 143         int i, i2, perm;
 144
 145         if (av == 0) {
 146                 audit_log_format(ab, " null");
 147                 return;
 148         }
 149
 150         for (i = 0; i < ARRAY_SIZE(av_inherit); i++) {
 151                 if (av_inherit[i].tclass == tclass) {
 152                         common_pts = av_inherit[i].common_pts;
 153                         common_base = av_inherit[i].common_base;
 154                         break;
 155                 }
 156         }
 157
 158         audit_log_format(ab, " {");
 159         i = 0;
 160         perm = 1;
 161         while (perm < common_base) {
 162                 if (perm & av) {
 163                         audit_log_format(ab, " %s", common_pts[i]);
 164                         av &= ~perm;
 165                 }
 166                 i++;
 167                 perm <<= 1;
 168         }
 169
 170         while (i < sizeof(av) * 8) {
 171                 if (perm & av) {
 172                         for (i2 = 0; i2 < ARRAY_SIZE(av_perm_to_string); i2++) {
 173                                 if ((av_perm_to_string[i2].tclass == tclass) &&
 174                                     (av_perm_to_string[i2].value == perm))
 175                                         break;
 176                         }
 177                         if (i2 < ARRAY_SIZE(av_perm_to_string)) {
 178                                 audit_log_format(ab, " %s",
 179                                                  av_perm_to_string[i2].name);
 180                                 av &= ~perm;
 181                         }
 182                 }
 183                 i++;
 184                 perm <<= 1;
 185         }
 186
 187         if (av)
 188                 audit_log_format(ab, " 0x%x", av);
 189
 190         audit_log_format(ab, " }");
 191 }
 192
 193 /**
 194  * avc_dump_query - Display a SID pair and a class in human-readable form.
 195  * @ssid: source security identifier
 196  * @tsid: target security identifier
 197  * @tclass: target security class
 198  */
 199 static void avc_dump_query(struct audit_buffer *ab, u32 ssid, u32 tsid, u16 tclass)
 200 {
 201         int rc;
 202         char *scontext;
 203         u32 scontext_len;
 204
 205         rc = security_sid_to_context(ssid, &scontext, &scontext_len);
 206         if (rc)
 207                 audit_log_format(ab, "ssid=%d", ssid);
 208         else {
 209                 audit_log_format(ab, "scontext=%s", scontext);
 210                 kfree(scontext);
 211         }
 212
 213         rc = security_sid_to_context(tsid, &scontext, &scontext_len);
 214         if (rc)
 215                 audit_log_format(ab, " tsid=%d", tsid);
 216         else {
 217                 audit_log_format(ab, " tcontext=%s", scontext);
 218                 kfree(scontext);
 219         }
 220         audit_log_format(ab, " tclass=%s", class_to_string[tclass]);
 221 }
 222
 223 /**
 224  * avc_init - Initialize the AVC.
 225  *
 226  * Initialize the access vector cache.
 227  */
 228 void __init avc_init(void)
 229 {
 230         int i;
 231
 232         for (i = 0; i < AVC_CACHE_SLOTS; i++) {
 233                 INIT_LIST_HEAD(&avc_cache.slots[i]);
 234                 spin_lock_init(&avc_cache.slots_lock[i]);
 235         }
 236         atomic_set(&avc_cache.active_nodes, 0);
 237         atomic_set(&avc_cache.lru_hint, 0);
 238
 239         avc_node_cachep = kmem_cache_create("avc_node", sizeof(struct avc_node),
 240                                              0, SLAB_PANIC, NULL, NULL);
 241
 242         audit_log(current->audit_context, GFP_KERNEL, AUDIT_KERNEL, "AVC INITIALIZED\n");
 243 }
 244
 245 int avc_get_hash_stats(char *page)
 246 {
 247         int i, chain_len, max_chain_len, slots_used;
 248         struct avc_node *node;
 249
 250         rcu_read_lock();
 251
 252         slots_used = 0;
 253         max_chain_len = 0;
 254         for (i = 0; i < AVC_CACHE_SLOTS; i++) {
 255                 if (!list_empty(&avc_cache.slots[i])) {
 256                         slots_used++;
 257                         chain_len = 0;
 258                         list_for_each_entry_rcu(node, &avc_cache.slots[i], list)
 259                                 chain_len++;
 260                         if (chain_len > max_chain_len)
 261                                 max_chain_len = chain_len;
 262                 }
 263         }
 264
 265         rcu_read_unlock();
 266
 267         return scnprintf(page, PAGE_SIZE, "entries: %d\nbuckets used: %d/%d\n"
 268                          "longest chain: %d\n",
 269                          atomic_read(&avc_cache.active_nodes),
 270                          slots_used, AVC_CACHE_SLOTS, max_chain_len);
 271 }
 272
 273 static void avc_node_free(struct rcu_head *rhead)
 274 {
 275         struct avc_node *node = container_of(rhead, struct avc_node, rhead);
 276         kmem_cache_free(avc_node_cachep, node);
 277         avc_cache_stats_incr(frees);
 278 }
 279
 280 static void avc_node_delete(struct avc_node *node)
 281 {
 282         list_del_rcu(&node->list);
 283         call_rcu(&node->rhead, avc_node_free);
 284         atomic_dec(&avc_cache.active_nodes);
 285 }
 286
 287 static void avc_node_kill(struct avc_node *node)
 288 {
 289         kmem_cache_free(avc_node_cachep, node);
 290         avc_cache_stats_incr(frees);
 291         atomic_dec(&avc_cache.active_nodes);
 292 }
 293
 294 static void avc_node_replace(struct avc_node *new, struct avc_node *old)
 295 {
 296         list_replace_rcu(&old->list, &new->list);
 297         call_rcu(&old->rhead, avc_node_free);
 298         atomic_dec(&avc_cache.active_nodes);
 299 }
 300
 301 static inline int avc_reclaim_node(void)
 302 {
 303         struct avc_node *node;
 304         int hvalue, try, ecx;
 305         unsigned long flags;
 306
 307         for (try = 0, ecx = 0; try < AVC_CACHE_SLOTS; try++ ) {
 308                 hvalue = atomic_inc_return(&avc_cache.lru_hint) & (AVC_CACHE_SLOTS - 1);
 309
 310                 if (!spin_trylock_irqsave(&avc_cache.slots_lock[hvalue], flags))
 311                         continue;
 312
 313                 list_for_each_entry(node, &avc_cache.slots[hvalue], list) {
 314                         if (atomic_dec_and_test(&node->ae.used)) {
 315                                 /* Recently Unused */
 316                                 avc_node_delete(node);
 317                                 avc_cache_stats_incr(reclaims);
 318                                 ecx++;
 319                                 if (ecx >= AVC_CACHE_RECLAIM) {
 320                                         spin_unlock_irqrestore(&avc_cache.slots_lock[hvalue], flags);
 321                                         goto out;
 322                                 }
 323                         }
 324                 }
 325                 spin_unlock_irqrestore(&avc_cache.slots_lock[hvalue], flags);
 326         }
 327 out:
 328         return ecx;
 329 }
 330
 331 static struct avc_node *avc_alloc_node(void)
 332 {
 333         struct avc_node *node;
 334
 335         node = kmem_cache_zalloc(avc_node_cachep, GFP_ATOMIC);
 336         if (!node)
 337                 goto out;
 338
 339         INIT_RCU_HEAD(&node->rhead);
 340         INIT_LIST_HEAD(&node->list);
 341         atomic_set(&node->ae.used, 1);
 342         avc_cache_stats_incr(allocations);
 343
 344         if (atomic_inc_return(&avc_cache.active_nodes) > avc_cache_threshold)
 345                 avc_reclaim_node();
 346
 347 out:
 348         return node;
 349 }
 350
 351 static void avc_node_populate(struct avc_node *node, u32 ssid, u32 tsid, u16 tclass, struct avc_entry *ae)
 352 {
 353         node->ae.ssid = ssid;
 354         node->ae.tsid = tsid;
 355         node->ae.tclass = tclass;
 356         memcpy(&node->ae.avd, &ae->avd, sizeof(node->ae.avd));
 357 }
 358
 359 static inline struct avc_node *avc_search_node(u32 ssid, u32 tsid, u16 tclass)
 360 {
 361         struct avc_node *node, *ret = NULL;
 362         int hvalue;
 363
 364         hvalue = avc_hash(ssid, tsid, tclass);
 365         list_for_each_entry_rcu(node, &avc_cache.slots[hvalue], list) {
 366                 if (ssid == node->ae.ssid &&
 367                     tclass == node->ae.tclass &&
 368                     tsid == node->ae.tsid) {
 369                         ret = node;
 370                         break;
 371                 }
 372         }
 373
 374         if (ret == NULL) {
 375                 /* cache miss */
 376                 goto out;
 377         }
 378
 379         /* cache hit */
 380         if (atomic_read(&ret->ae.used) != 1)
 381                 atomic_set(&ret->ae.used, 1);
 382 out:
 383         return ret;
 384 }
 385
 386 /**
 387  * avc_lookup - Look up an AVC entry.
 388  * @ssid: source security identifier
 389  * @tsid: target security identifier
 390  * @tclass: target security class
 391  * @requested: requested permissions, interpreted based on @tclass
 392  *
 393  * Look up an AVC entry that is valid for the
 394  * @requested permissions between the SID pair
 395  * (@ssid, @tsid), interpreting the permissions
 396  * based on @tclass.  If a valid AVC entry exists,
 397  * then this function return the avc_node.
 398  * Otherwise, this function returns NULL.
 399  */
 400 static struct avc_node *avc_lookup(u32 ssid, u32 tsid, u16 tclass, u32 requested)
 401 {
 402         struct avc_node *node;
 403
 404         avc_cache_stats_incr(lookups);
 405         node = avc_search_node(ssid, tsid, tclass);
 406
 407         if (node && ((node->ae.avd.decided & requested) == requested)) {
 408                 avc_cache_stats_incr(hits);
 409                 goto out;
 410         }
 411
 412         node = NULL;
 413         avc_cache_stats_incr(misses);
 414 out:
 415         return node;
 416 }
 417
 418 static int avc_latest_notif_update(int seqno, int is_insert)
 419 {
 420         int ret = 0;
 421         static DEFINE_SPINLOCK(notif_lock);
 422         unsigned long flag;
 423
 424         spin_lock_irqsave(&notif_lock, flag);
 425         if (is_insert) {
 426                 if (seqno < avc_cache.latest_notif) {
 427                         printk(KERN_WARNING "avc:  seqno %d < latest_notif %d\n",
 428                                seqno, avc_cache.latest_notif);
 429                         ret = -EAGAIN;
 430                 }
 431         } else {
 432                 if (seqno > avc_cache.latest_notif)
 433                         avc_cache.latest_notif = seqno;
 434         }
 435         spin_unlock_irqrestore(&notif_lock, flag);
 436
 437         return ret;
 438 }
 439
 440 /**
 441  * avc_insert - Insert an AVC entry.
 442  * @ssid: source security identifier
 443  * @tsid: target security identifier
 444  * @tclass: target security class
 445  * @ae: AVC entry
 446  *
 447  * Insert an AVC entry for the SID pair
 448  * (@ssid, @tsid) and class @tclass.
 449  * The access vectors and the sequence number are
 450  * normally provided by the security server in
 451  * response to a security_compute_av() call.  If the
 452  * sequence number @ae->avd.seqno is not less than the latest
 453  * revocation notification, then the function copies
 454  * the access vectors into a cache entry, returns
 455  * avc_node inserted. Otherwise, this function returns NULL.
 456  */
 457 static struct avc_node *avc_insert(u32 ssid, u32 tsid, u16 tclass, struct avc_entry *ae)
 458 {
 459         struct avc_node *pos, *node = NULL;
 460         int hvalue;
 461         unsigned long flag;
 462
 463         if (avc_latest_notif_update(ae->avd.seqno, 1))
 464                 goto out;
 465
 466         node = avc_alloc_node();
 467         if (node) {
 468                 hvalue = avc_hash(ssid, tsid, tclass);
 469                 avc_node_populate(node, ssid, tsid, tclass, ae);
 470
 471                 spin_lock_irqsave(&avc_cache.slots_lock[hvalue], flag);
 472                 list_for_each_entry(pos, &avc_cache.slots[hvalue], list) {
 473                         if (pos->ae.ssid == ssid &&
 474                             pos->ae.tsid == tsid &&
 475                             pos->ae.tclass == tclass) {
 476                                 avc_node_replace(node, pos);
 477                                 goto found;
 478                         }
 479                 }
 480                 list_add_rcu(&node->list, &avc_cache.slots[hvalue]);
 481 found:
 482                 spin_unlock_irqrestore(&avc_cache.slots_lock[hvalue], flag);
 483         }
 484 out:
 485         return node;
 486 }
 487
 488 static inline void avc_print_ipv6_addr(struct audit_buffer *ab,
 489                                        struct in6_addr *addr, __be16 port,
 490                                        char *name1, char *name2)
 491 {
 492         if (!ipv6_addr_any(addr))
 493                 audit_log_format(ab, " %s=" NIP6_FMT, name1, NIP6(*addr));
 494         if (port)
 495                 audit_log_format(ab, " %s=%d", name2, ntohs(port));
 496 }
 497
 498 static inline void avc_print_ipv4_addr(struct audit_buffer *ab, __be32 addr,
 499                                        __be16 port, char *name1, char *name2)
 500 {
 501         if (addr)
 502                 audit_log_format(ab, " %s=" NIPQUAD_FMT, name1, NIPQUAD(addr));
 503         if (port)
 504                 audit_log_format(ab, " %s=%d", name2, ntohs(port));
 505 }
 506
 507 /**
 508  * avc_audit - Audit the granting or denial of permissions.
 509  * @ssid: source security identifier
 510  * @tsid: target security identifier
 511  * @tclass: target security class
 512  * @requested: requested permissions
 513  * @avd: access vector decisions
 514  * @result: result from avc_has_perm_noaudit
 515  * @a:  auxiliary audit data
 516  *
 517  * Audit the granting or denial of permissions in accordance
 518  * with the policy.  This function is typically called by
 519  * avc_has_perm() after a permission check, but can also be
 520  * called directly by callers who use avc_has_perm_noaudit()
 521  * in order to separate the permission check from the auditing.
 522  * For example, this separation is useful when the permission check must
 523  * be performed under a lock, to allow the lock to be released
 524  * before calling the auditing code.
 525  */
 526 void avc_audit(u32 ssid, u32 tsid,
 527                u16 tclass, u32 requested,
 528                struct av_decision *avd, int result, struct avc_audit_data *a)
 529 {
 530         struct task_struct *tsk = current;
 531         struct inode *inode = NULL;
 532         u32 denied, audited;
 533         struct audit_buffer *ab;
 534
 535         denied = requested & ~avd->allowed;
 536         if (denied) {
 537                 audited = denied;
 538                 if (!(audited & avd->auditdeny))
 539                         return;
 540         } else if (result) {
 541                 audited = denied = requested;
 542         } else {
 543                 audited = requested;
 544                 if (!(audited & avd->auditallow))
 545                         return;
 546         }
 547
 548         ab = audit_log_start(current->audit_context, GFP_ATOMIC, AUDIT_AVC);
 549         if (!ab)
 550                 return;         /* audit_panic has been called */
 551         audit_log_format(ab, "avc:  %s ", denied ? "denied" : "granted");
 552         avc_dump_av(ab, tclass,audited);
 553         audit_log_format(ab, " for ");
 554         if (a && a->tsk)
 555                 tsk = a->tsk;
 556         if (tsk && tsk->pid) {
 557                 audit_log_format(ab, " pid=%d comm=", tsk->pid);
 558                 audit_log_untrustedstring(ab, tsk->comm);
 559         }
 560         if (a) {
 561                 switch (a->type) {
 562                 case AVC_AUDIT_DATA_IPC:
 563                         audit_log_format(ab, " key=%d", a->u.ipc_id);
 564                         break;
 565                 case AVC_AUDIT_DATA_CAP:
 566                         audit_log_format(ab, " capability=%d", a->u.cap);
 567                         break;
 568                 case AVC_AUDIT_DATA_FS:
 569                         if (a->u.fs.dentry) {
 570                                 struct dentry *dentry = a->u.fs.dentry;
 571                                 if (a->u.fs.mnt)
 572                                         audit_avc_path(dentry, a->u.fs.mnt);
 573                                 audit_log_format(ab, " name=");
 574                                 audit_log_untrustedstring(ab, dentry->d_name.name);
 575                                 inode = dentry->d_inode;
 576                         } else if (a->u.fs.inode) {
 577                                 struct dentry *dentry;
 578                                 inode = a->u.fs.inode;
 579                                 dentry = d_find_alias(inode);
 580                                 if (dentry) {
 581                                         audit_log_format(ab, " name=");
 582                                         audit_log_untrustedstring(ab, dentry->d_name.name);
 583                                         dput(dentry);
 584                                 }
 585                         }
 586                         if (inode)
 587                                 audit_log_format(ab, " dev=%s ino=%ld",
 588                                                  inode->i_sb->s_id,
 589                                                  inode->i_ino);
 590                         break;
 591                 case AVC_AUDIT_DATA_NET:
 592                         if (a->u.net.sk) {
 593                                 struct sock *sk = a->u.net.sk;
 594                                 struct unix_sock *u;
 595                                 int len = 0;
 596                                 char *p = NULL;
 597
 598                                 switch (sk->sk_family) {
 599                                 case AF_INET: {
 600                                         struct inet_sock *inet = inet_sk(sk);
 601
 602                                         avc_print_ipv4_addr(ab, inet->rcv_saddr,
 603                                                             inet->sport,
 604                                                             "laddr", "lport");
 605                                         avc_print_ipv4_addr(ab, inet->daddr,
 606                                                             inet->dport,
 607                                                             "faddr", "fport");
 608                                         break;
 609                                 }
 610                                 case AF_INET6: {
 611                                         struct inet_sock *inet = inet_sk(sk);
 612                                         struct ipv6_pinfo *inet6 = inet6_sk(sk);
 613
 614                                         avc_print_ipv6_addr(ab, &inet6->rcv_saddr,
 615                                                             inet->sport,
 616                                                             "laddr", "lport");
 617                                         avc_print_ipv6_addr(ab, &inet6->daddr,
 618                                                             inet->dport,
 619                                                             "faddr", "fport");
 620                                         break;
 621                                 }
 622                                 case AF_UNIX:
 623                                         u = unix_sk(sk);
 624                                         if (u->dentry) {
 625                                                 audit_avc_path(u->dentry, u->mnt);
 626                                                 audit_log_format(ab, " name=");
 627                                                 audit_log_untrustedstring(ab, u->dentry->d_name.name);
 628                                                 break;
 629                                         }
 630                                         if (!u->addr)
 631                                                 break;
 632                                         len = u->addr->len-sizeof(short);
 633                                         p = &u->addr->name->sun_path[0];
 634                                         audit_log_format(ab, " path=");
 635                                         if (*p)
 636                                                 audit_log_untrustedstring(ab, p);
 637                                         else
 638                                                 audit_log_hex(ab, p, len);
 639                                         break;
 640                                 }
 641                         }
 642
 643                         switch (a->u.net.family) {
 644                         case AF_INET:
 645                                 avc_print_ipv4_addr(ab, a->u.net.v4info.saddr,
 646                                                     a->u.net.sport,
 647                                                     "saddr", "src");
 648                                 avc_print_ipv4_addr(ab, a->u.net.v4info.daddr,
 649                                                     a->u.net.dport,
 650                                                     "daddr", "dest");
 651                                 break;
 652                         case AF_INET6:
 653                                 avc_print_ipv6_addr(ab, &a->u.net.v6info.saddr,
 654                                                     a->u.net.sport,
 655                                                     "saddr", "src");
 656                                 avc_print_ipv6_addr(ab, &a->u.net.v6info.daddr,
 657                                                     a->u.net.dport,
 658                                                     "daddr", "dest");
 659                                 break;
 660                         }
 661                         if (a->u.net.netif)
 662                                 audit_log_format(ab, " netif=%s",
 663                                         a->u.net.netif);
 664                         break;
 665                 }
 666         }
 667         audit_log_format(ab, " ");
 668         avc_dump_query(ab, ssid, tsid, tclass);
 669         audit_log_end(ab);
 670 }
 671
 672 /**
 673  * avc_add_callback - Register a callback for security events.
 674  * @callback: callback function
 675  * @events: security events
 676  * @ssid: source security identifier or %SECSID_WILD
 677  * @tsid: target security identifier or %SECSID_WILD
 678  * @tclass: target security class
 679  * @perms: permissions
 680  *
 681  * Register a callback function for events in the set @events
 682  * related to the SID pair (@ssid, @tsid) and
 683  * and the permissions @perms, interpreting
 684  * @perms based on @tclass.  Returns %0 on success or
 685  * -%ENOMEM if insufficient memory exists to add the callback.
 686  */
 687 int avc_add_callback(int (*callback)(u32 event, u32 ssid, u32 tsid,
 688                                      u16 tclass, u32 perms,
 689                                      u32 *out_retained),
 690                      u32 events, u32 ssid, u32 tsid,
 691                      u16 tclass, u32 perms)
 692 {
 693         struct avc_callback_node *c;
 694         int rc = 0;
 695
 696         c = kmalloc(sizeof(*c), GFP_ATOMIC);
 697         if (!c) {
 698                 rc = -ENOMEM;
 699                 goto out;
 700         }
 701
 702         c->callback = callback;
 703         c->events = events;
 704         c->ssid = ssid;
 705         c->tsid = tsid;
 706         c->perms = perms;
 707         c->next = avc_callbacks;
 708         avc_callbacks = c;
 709 out:
 710         return rc;
 711 }
 712
 713 static inline int avc_sidcmp(u32 x, u32 y)
 714 {
 715         return (x == y || x == SECSID_WILD || y == SECSID_WILD);
 716 }
 717
 718 /**
 719  * avc_update_node Update an AVC entry
 720  * @event : Updating event
 721  * @perms : Permission mask bits
 722  * @ssid,@tsid,@tclass : identifier of an AVC entry
 723  *
 724  * if a valid AVC entry doesn't exist,this function returns -ENOENT.
 725  * if kmalloc() called internal returns NULL, this function returns -ENOMEM.
 726  * otherwise, this function update the AVC entry. The original AVC-entry object
 727  * will release later by RCU.
 728  */
 729 static int avc_update_node(u32 event, u32 perms, u32 ssid, u32 tsid, u16 tclass)
 730 {
 731         int hvalue, rc = 0;
 732         unsigned long flag;
 733         struct avc_node *pos, *node, *orig = NULL;
 734
 735         node = avc_alloc_node();
 736         if (!node) {
 737                 rc = -ENOMEM;
 738                 goto out;
 739         }
 740
 741         /* Lock the target slot */
 742         hvalue = avc_hash(ssid, tsid, tclass);
 743         spin_lock_irqsave(&avc_cache.slots_lock[hvalue], flag);
 744
 745         list_for_each_entry(pos, &avc_cache.slots[hvalue], list){
 746                 if ( ssid==pos->ae.ssid &&
 747                      tsid==pos->ae.tsid &&
 748                      tclass==pos->ae.tclass ){
 749                         orig = pos;
 750                         break;
 751                 }
 752         }
 753
 754         if (!orig) {
 755                 rc = -ENOENT;
 756                 avc_node_kill(node);
 757                 goto out_unlock;
 758         }
 759
 760         /*
 761          * Copy and replace original node.
 762          */
 763
 764         avc_node_populate(node, ssid, tsid, tclass, &orig->ae);
 765
 766         switch (event) {
 767         case AVC_CALLBACK_GRANT:
 768                 node->ae.avd.allowed |= perms;
 769                 break;
 770         case AVC_CALLBACK_TRY_REVOKE:
 771         case AVC_CALLBACK_REVOKE:
 772                 node->ae.avd.allowed &= ~perms;
 773                 break;
 774         case AVC_CALLBACK_AUDITALLOW_ENABLE:
 775                 node->ae.avd.auditallow |= perms;
 776                 break;
 777         case AVC_CALLBACK_AUDITALLOW_DISABLE:
 778                 node->ae.avd.auditallow &= ~perms;
 779                 break;
 780         case AVC_CALLBACK_AUDITDENY_ENABLE:
 781                 node->ae.avd.auditdeny |= perms;
 782                 break;
 783         case AVC_CALLBACK_AUDITDENY_DISABLE:
 784                 node->ae.avd.auditdeny &= ~perms;
 785                 break;
 786         }
 787         avc_node_replace(node, orig);
 788 out_unlock:
 789         spin_unlock_irqrestore(&avc_cache.slots_lock[hvalue], flag);
 790 out:
 791         return rc;
 792 }
 793
 794 /**
 795  * avc_ss_reset - Flush the cache and revalidate migrated permissions.
 796  * @seqno: policy sequence number
 797  */
 798 int avc_ss_reset(u32 seqno)
 799 {
 800         struct avc_callback_node *c;
 801         int i, rc = 0, tmprc;
 802         unsigned long flag;
 803         struct avc_node *node;
 804
 805         for (i = 0; i < AVC_CACHE_SLOTS; i++) {
 806                 spin_lock_irqsave(&avc_cache.slots_lock[i], flag);
 807                 list_for_each_entry(node, &avc_cache.slots[i], list)
 808                         avc_node_delete(node);
 809                 spin_unlock_irqrestore(&avc_cache.slots_lock[i], flag);
 810         }
 811
 812         for (c = avc_callbacks; c; c = c->next) {
 813                 if (c->events & AVC_CALLBACK_RESET) {
 814                         tmprc = c->callback(AVC_CALLBACK_RESET,
 815                                             0, 0, 0, 0, NULL);
 816                         /* save the first error encountered for the return
 817                            value and continue processing the callbacks */
 818                         if (!rc)
 819                                 rc = tmprc;
 820                 }
 821         }
 822
 823         avc_latest_notif_update(seqno, 0);
 824         return rc;
 825 }
 826
 827 /**
 828  * avc_has_perm_noaudit - Check permissions but perform no auditing.
 829  * @ssid: source security identifier
 830  * @tsid: target security identifier
 831  * @tclass: target security class
 832  * @requested: requested permissions, interpreted based on @tclass
 833  * @avd: access vector decisions
 834  *
 835  * Check the AVC to determine whether the @requested permissions are granted
 836  * for the SID pair (@ssid, @tsid), interpreting the permissions
 837  * based on @tclass, and call the security server on a cache miss to obtain
 838  * a new decision and add it to the cache.  Return a copy of the decisions
 839  * in @avd.  Return %0 if all @requested permissions are granted,
 840  * -%EACCES if any permissions are denied, or another -errno upon
 841  * other errors.  This function is typically called by avc_has_perm(),
 842  * but may also be called directly to separate permission checking from
 843  * auditing, e.g. in cases where a lock must be held for the check but
 844  * should be released for the auditing.
 845  */
 846 int avc_has_perm_noaudit(u32 ssid, u32 tsid,
 847                          u16 tclass, u32 requested,
 848                          struct av_decision *avd)
 849 {
 850         struct avc_node *node;
 851         struct avc_entry entry, *p_ae;
 852         int rc = 0;
 853         u32 denied;
 854
 855         rcu_read_lock();
 856
 857         node = avc_lookup(ssid, tsid, tclass, requested);
 858         if (!node) {
 859                 rcu_read_unlock();
 860                 rc = security_compute_av(ssid,tsid,tclass,requested,&entry.avd);
 861                 if (rc)
 862                         goto out;
 863                 rcu_read_lock();
 864                 node = avc_insert(ssid,tsid,tclass,&entry);
 865         }
 866
 867         p_ae = node ? &node->ae : &entry;
 868
 869         if (avd)
 870                 memcpy(avd, &p_ae->avd, sizeof(*avd));
 871
 872         denied = requested & ~(p_ae->avd.allowed);
 873
 874         if (!requested || denied) {
 875                 if (selinux_enforcing)
 876                         rc = -EACCES;
 877                 else
 878                         if (node)
 879                                 avc_update_node(AVC_CALLBACK_GRANT,requested,
 880                                                 ssid,tsid,tclass);
 881         }
 882
 883         rcu_read_unlock();
 884 out:
 885         return rc;
 886 }
 887
 888 /**
 889  * avc_has_perm - Check permissions and perform any appropriate auditing.
 890  * @ssid: source security identifier
 891  * @tsid: target security identifier
 892  * @tclass: target security class
 893  * @requested: requested permissions, interpreted based on @tclass
 894  * @auditdata: auxiliary audit data
 895  *
 896  * Check the AVC to determine whether the @requested permissions are granted
 897  * for the SID pair (@ssid, @tsid), interpreting the permissions
 898  * based on @tclass, and call the security server on a cache miss to obtain
 899  * a new decision and add it to the cache.  Audit the granting or denial of
 900  * permissions in accordance with the policy.  Return %0 if all @requested
 901  * permissions are granted, -%EACCES if any permissions are denied, or
 902  * another -errno upon other errors.
 903  */
 904 int avc_has_perm(u32 ssid, u32 tsid, u16 tclass,
 905                  u32 requested, struct avc_audit_data *auditdata)
 906 {
 907         struct av_decision avd;
 908         int rc;
 909
 910         rc = avc_has_perm_noaudit(ssid, tsid, tclass, requested, &avd);
 911         avc_audit(ssid, tsid, tclass, requested, &avd, rc, auditdata);
 912         return rc;
 913 }