avc.c 23 KB

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  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. static const struct av_perm_to_string av_perm_to_string[] = {
  35. #define S_(c, v, s) { c, v, s },
  36. #include "av_perm_to_string.h"
  37. #undef S_
  38. };
  39. static const char *class_to_string[] = {
  40. #define S_(s) s,
  41. #include "class_to_string.h"
  42. #undef S_
  43. };
  44. #define TB_(s) static const char * s [] = {
  45. #define TE_(s) };
  46. #define S_(s) s,
  47. #include "common_perm_to_string.h"
  48. #undef TB_
  49. #undef TE_
  50. #undef S_
  51. static const struct av_inherit av_inherit[] = {
  52. #define S_(c, i, b) { c, common_##i##_perm_to_string, b },
  53. #include "av_inherit.h"
  54. #undef S_
  55. };
  56. const struct selinux_class_perm selinux_class_perm = {
  57. av_perm_to_string,
  58. ARRAY_SIZE(av_perm_to_string),
  59. class_to_string,
  60. ARRAY_SIZE(class_to_string),
  61. av_inherit,
  62. ARRAY_SIZE(av_inherit)
  63. };
  64. #define AVC_CACHE_SLOTS 512
  65. #define AVC_DEF_CACHE_THRESHOLD 512
  66. #define AVC_CACHE_RECLAIM 16
  67. #ifdef CONFIG_SECURITY_SELINUX_AVC_STATS
  68. #define avc_cache_stats_incr(field) \
  69. do { \
  70. per_cpu(avc_cache_stats, get_cpu()).field++; \
  71. put_cpu(); \
  72. } while (0)
  73. #else
  74. #define avc_cache_stats_incr(field) do {} while (0)
  75. #endif
  76. struct avc_entry {
  77. u32 ssid;
  78. u32 tsid;
  79. u16 tclass;
  80. struct av_decision avd;
  81. atomic_t used; /* used recently */
  82. };
  83. struct avc_node {
  84. struct avc_entry ae;
  85. struct list_head list;
  86. struct rcu_head rhead;
  87. };
  88. struct avc_cache {
  89. struct list_head slots[AVC_CACHE_SLOTS];
  90. spinlock_t slots_lock[AVC_CACHE_SLOTS]; /* lock for writes */
  91. atomic_t lru_hint; /* LRU hint for reclaim scan */
  92. atomic_t active_nodes;
  93. u32 latest_notif; /* latest revocation notification */
  94. };
  95. struct avc_callback_node {
  96. int (*callback) (u32 event, u32 ssid, u32 tsid,
  97. u16 tclass, u32 perms,
  98. u32 *out_retained);
  99. u32 events;
  100. u32 ssid;
  101. u32 tsid;
  102. u16 tclass;
  103. u32 perms;
  104. struct avc_callback_node *next;
  105. };
  106. /* Exported via selinufs */
  107. unsigned int avc_cache_threshold = AVC_DEF_CACHE_THRESHOLD;
  108. #ifdef CONFIG_SECURITY_SELINUX_AVC_STATS
  109. DEFINE_PER_CPU(struct avc_cache_stats, avc_cache_stats) = { 0 };
  110. #endif
  111. static struct avc_cache avc_cache;
  112. static struct avc_callback_node *avc_callbacks;
  113. static struct kmem_cache *avc_node_cachep;
  114. static inline int avc_hash(u32 ssid, u32 tsid, u16 tclass)
  115. {
  116. return (ssid ^ (tsid<<2) ^ (tclass<<4)) & (AVC_CACHE_SLOTS - 1);
  117. }
  118. /**
  119. * avc_dump_av - Display an access vector in human-readable form.
  120. * @tclass: target security class
  121. * @av: access vector
  122. */
  123. static void avc_dump_av(struct audit_buffer *ab, u16 tclass, u32 av)
  124. {
  125. const char **common_pts = NULL;
  126. u32 common_base = 0;
  127. int i, i2, perm;
  128. if (av == 0) {
  129. audit_log_format(ab, " null");
  130. return;
  131. }
  132. for (i = 0; i < ARRAY_SIZE(av_inherit); i++) {
  133. if (av_inherit[i].tclass == tclass) {
  134. common_pts = av_inherit[i].common_pts;
  135. common_base = av_inherit[i].common_base;
  136. break;
  137. }
  138. }
  139. audit_log_format(ab, " {");
  140. i = 0;
  141. perm = 1;
  142. while (perm < common_base) {
  143. if (perm & av) {
  144. audit_log_format(ab, " %s", common_pts[i]);
  145. av &= ~perm;
  146. }
  147. i++;
  148. perm <<= 1;
  149. }
  150. while (i < sizeof(av) * 8) {
  151. if (perm & av) {
  152. for (i2 = 0; i2 < ARRAY_SIZE(av_perm_to_string); i2++) {
  153. if ((av_perm_to_string[i2].tclass == tclass) &&
  154. (av_perm_to_string[i2].value == perm))
  155. break;
  156. }
  157. if (i2 < ARRAY_SIZE(av_perm_to_string)) {
  158. audit_log_format(ab, " %s",
  159. av_perm_to_string[i2].name);
  160. av &= ~perm;
  161. }
  162. }
  163. i++;
  164. perm <<= 1;
  165. }
  166. if (av)
  167. audit_log_format(ab, " 0x%x", av);
  168. audit_log_format(ab, " }");
  169. }
  170. /**
  171. * avc_dump_query - Display a SID pair and a class in human-readable form.
  172. * @ssid: source security identifier
  173. * @tsid: target security identifier
  174. * @tclass: target security class
  175. */
  176. static void avc_dump_query(struct audit_buffer *ab, u32 ssid, u32 tsid, u16 tclass)
  177. {
  178. int rc;
  179. char *scontext;
  180. u32 scontext_len;
  181. rc = security_sid_to_context(ssid, &scontext, &scontext_len);
  182. if (rc)
  183. audit_log_format(ab, "ssid=%d", ssid);
  184. else {
  185. audit_log_format(ab, "scontext=%s", scontext);
  186. kfree(scontext);
  187. }
  188. rc = security_sid_to_context(tsid, &scontext, &scontext_len);
  189. if (rc)
  190. audit_log_format(ab, " tsid=%d", tsid);
  191. else {
  192. audit_log_format(ab, " tcontext=%s", scontext);
  193. kfree(scontext);
  194. }
  195. audit_log_format(ab, " tclass=%s", class_to_string[tclass]);
  196. }
  197. /**
  198. * avc_init - Initialize the AVC.
  199. *
  200. * Initialize the access vector cache.
  201. */
  202. void __init avc_init(void)
  203. {
  204. int i;
  205. for (i = 0; i < AVC_CACHE_SLOTS; i++) {
  206. INIT_LIST_HEAD(&avc_cache.slots[i]);
  207. spin_lock_init(&avc_cache.slots_lock[i]);
  208. }
  209. atomic_set(&avc_cache.active_nodes, 0);
  210. atomic_set(&avc_cache.lru_hint, 0);
  211. avc_node_cachep = kmem_cache_create("avc_node", sizeof(struct avc_node),
  212. 0, SLAB_PANIC, NULL, NULL);
  213. audit_log(current->audit_context, GFP_KERNEL, AUDIT_KERNEL, "AVC INITIALIZED\n");
  214. }
  215. int avc_get_hash_stats(char *page)
  216. {
  217. int i, chain_len, max_chain_len, slots_used;
  218. struct avc_node *node;
  219. rcu_read_lock();
  220. slots_used = 0;
  221. max_chain_len = 0;
  222. for (i = 0; i < AVC_CACHE_SLOTS; i++) {
  223. if (!list_empty(&avc_cache.slots[i])) {
  224. slots_used++;
  225. chain_len = 0;
  226. list_for_each_entry_rcu(node, &avc_cache.slots[i], list)
  227. chain_len++;
  228. if (chain_len > max_chain_len)
  229. max_chain_len = chain_len;
  230. }
  231. }
  232. rcu_read_unlock();
  233. return scnprintf(page, PAGE_SIZE, "entries: %d\nbuckets used: %d/%d\n"
  234. "longest chain: %d\n",
  235. atomic_read(&avc_cache.active_nodes),
  236. slots_used, AVC_CACHE_SLOTS, max_chain_len);
  237. }
  238. static void avc_node_free(struct rcu_head *rhead)
  239. {
  240. struct avc_node *node = container_of(rhead, struct avc_node, rhead);
  241. kmem_cache_free(avc_node_cachep, node);
  242. avc_cache_stats_incr(frees);
  243. }
  244. static void avc_node_delete(struct avc_node *node)
  245. {
  246. list_del_rcu(&node->list);
  247. call_rcu(&node->rhead, avc_node_free);
  248. atomic_dec(&avc_cache.active_nodes);
  249. }
  250. static void avc_node_kill(struct avc_node *node)
  251. {
  252. kmem_cache_free(avc_node_cachep, node);
  253. avc_cache_stats_incr(frees);
  254. atomic_dec(&avc_cache.active_nodes);
  255. }
  256. static void avc_node_replace(struct avc_node *new, struct avc_node *old)
  257. {
  258. list_replace_rcu(&old->list, &new->list);
  259. call_rcu(&old->rhead, avc_node_free);
  260. atomic_dec(&avc_cache.active_nodes);
  261. }
  262. static inline int avc_reclaim_node(void)
  263. {
  264. struct avc_node *node;
  265. int hvalue, try, ecx;
  266. unsigned long flags;
  267. for (try = 0, ecx = 0; try < AVC_CACHE_SLOTS; try++ ) {
  268. hvalue = atomic_inc_return(&avc_cache.lru_hint) & (AVC_CACHE_SLOTS - 1);
  269. if (!spin_trylock_irqsave(&avc_cache.slots_lock[hvalue], flags))
  270. continue;
  271. list_for_each_entry(node, &avc_cache.slots[hvalue], list) {
  272. if (atomic_dec_and_test(&node->ae.used)) {
  273. /* Recently Unused */
  274. avc_node_delete(node);
  275. avc_cache_stats_incr(reclaims);
  276. ecx++;
  277. if (ecx >= AVC_CACHE_RECLAIM) {
  278. spin_unlock_irqrestore(&avc_cache.slots_lock[hvalue], flags);
  279. goto out;
  280. }
  281. }
  282. }
  283. spin_unlock_irqrestore(&avc_cache.slots_lock[hvalue], flags);
  284. }
  285. out:
  286. return ecx;
  287. }
  288. static struct avc_node *avc_alloc_node(void)
  289. {
  290. struct avc_node *node;
  291. node = kmem_cache_zalloc(avc_node_cachep, GFP_ATOMIC);
  292. if (!node)
  293. goto out;
  294. INIT_RCU_HEAD(&node->rhead);
  295. INIT_LIST_HEAD(&node->list);
  296. atomic_set(&node->ae.used, 1);
  297. avc_cache_stats_incr(allocations);
  298. if (atomic_inc_return(&avc_cache.active_nodes) > avc_cache_threshold)
  299. avc_reclaim_node();
  300. out:
  301. return node;
  302. }
  303. static void avc_node_populate(struct avc_node *node, u32 ssid, u32 tsid, u16 tclass, struct avc_entry *ae)
  304. {
  305. node->ae.ssid = ssid;
  306. node->ae.tsid = tsid;
  307. node->ae.tclass = tclass;
  308. memcpy(&node->ae.avd, &ae->avd, sizeof(node->ae.avd));
  309. }
  310. static inline struct avc_node *avc_search_node(u32 ssid, u32 tsid, u16 tclass)
  311. {
  312. struct avc_node *node, *ret = NULL;
  313. int hvalue;
  314. hvalue = avc_hash(ssid, tsid, tclass);
  315. list_for_each_entry_rcu(node, &avc_cache.slots[hvalue], list) {
  316. if (ssid == node->ae.ssid &&
  317. tclass == node->ae.tclass &&
  318. tsid == node->ae.tsid) {
  319. ret = node;
  320. break;
  321. }
  322. }
  323. if (ret == NULL) {
  324. /* cache miss */
  325. goto out;
  326. }
  327. /* cache hit */
  328. if (atomic_read(&ret->ae.used) != 1)
  329. atomic_set(&ret->ae.used, 1);
  330. out:
  331. return ret;
  332. }
  333. /**
  334. * avc_lookup - Look up an AVC entry.
  335. * @ssid: source security identifier
  336. * @tsid: target security identifier
  337. * @tclass: target security class
  338. * @requested: requested permissions, interpreted based on @tclass
  339. *
  340. * Look up an AVC entry that is valid for the
  341. * @requested permissions between the SID pair
  342. * (@ssid, @tsid), interpreting the permissions
  343. * based on @tclass. If a valid AVC entry exists,
  344. * then this function return the avc_node.
  345. * Otherwise, this function returns NULL.
  346. */
  347. static struct avc_node *avc_lookup(u32 ssid, u32 tsid, u16 tclass, u32 requested)
  348. {
  349. struct avc_node *node;
  350. avc_cache_stats_incr(lookups);
  351. node = avc_search_node(ssid, tsid, tclass);
  352. if (node && ((node->ae.avd.decided & requested) == requested)) {
  353. avc_cache_stats_incr(hits);
  354. goto out;
  355. }
  356. node = NULL;
  357. avc_cache_stats_incr(misses);
  358. out:
  359. return node;
  360. }
  361. static int avc_latest_notif_update(int seqno, int is_insert)
  362. {
  363. int ret = 0;
  364. static DEFINE_SPINLOCK(notif_lock);
  365. unsigned long flag;
  366. spin_lock_irqsave(&notif_lock, flag);
  367. if (is_insert) {
  368. if (seqno < avc_cache.latest_notif) {
  369. printk(KERN_WARNING "avc: seqno %d < latest_notif %d\n",
  370. seqno, avc_cache.latest_notif);
  371. ret = -EAGAIN;
  372. }
  373. } else {
  374. if (seqno > avc_cache.latest_notif)
  375. avc_cache.latest_notif = seqno;
  376. }
  377. spin_unlock_irqrestore(&notif_lock, flag);
  378. return ret;
  379. }
  380. /**
  381. * avc_insert - Insert an AVC entry.
  382. * @ssid: source security identifier
  383. * @tsid: target security identifier
  384. * @tclass: target security class
  385. * @ae: AVC entry
  386. *
  387. * Insert an AVC entry for the SID pair
  388. * (@ssid, @tsid) and class @tclass.
  389. * The access vectors and the sequence number are
  390. * normally provided by the security server in
  391. * response to a security_compute_av() call. If the
  392. * sequence number @ae->avd.seqno is not less than the latest
  393. * revocation notification, then the function copies
  394. * the access vectors into a cache entry, returns
  395. * avc_node inserted. Otherwise, this function returns NULL.
  396. */
  397. static struct avc_node *avc_insert(u32 ssid, u32 tsid, u16 tclass, struct avc_entry *ae)
  398. {
  399. struct avc_node *pos, *node = NULL;
  400. int hvalue;
  401. unsigned long flag;
  402. if (avc_latest_notif_update(ae->avd.seqno, 1))
  403. goto out;
  404. node = avc_alloc_node();
  405. if (node) {
  406. hvalue = avc_hash(ssid, tsid, tclass);
  407. avc_node_populate(node, ssid, tsid, tclass, ae);
  408. spin_lock_irqsave(&avc_cache.slots_lock[hvalue], flag);
  409. list_for_each_entry(pos, &avc_cache.slots[hvalue], list) {
  410. if (pos->ae.ssid == ssid &&
  411. pos->ae.tsid == tsid &&
  412. pos->ae.tclass == tclass) {
  413. avc_node_replace(node, pos);
  414. goto found;
  415. }
  416. }
  417. list_add_rcu(&node->list, &avc_cache.slots[hvalue]);
  418. found:
  419. spin_unlock_irqrestore(&avc_cache.slots_lock[hvalue], flag);
  420. }
  421. out:
  422. return node;
  423. }
  424. static inline void avc_print_ipv6_addr(struct audit_buffer *ab,
  425. struct in6_addr *addr, __be16 port,
  426. char *name1, char *name2)
  427. {
  428. if (!ipv6_addr_any(addr))
  429. audit_log_format(ab, " %s=" NIP6_FMT, name1, NIP6(*addr));
  430. if (port)
  431. audit_log_format(ab, " %s=%d", name2, ntohs(port));
  432. }
  433. static inline void avc_print_ipv4_addr(struct audit_buffer *ab, __be32 addr,
  434. __be16 port, char *name1, char *name2)
  435. {
  436. if (addr)
  437. audit_log_format(ab, " %s=" NIPQUAD_FMT, name1, NIPQUAD(addr));
  438. if (port)
  439. audit_log_format(ab, " %s=%d", name2, ntohs(port));
  440. }
  441. /**
  442. * avc_audit - Audit the granting or denial of permissions.
  443. * @ssid: source security identifier
  444. * @tsid: target security identifier
  445. * @tclass: target security class
  446. * @requested: requested permissions
  447. * @avd: access vector decisions
  448. * @result: result from avc_has_perm_noaudit
  449. * @a: auxiliary audit data
  450. *
  451. * Audit the granting or denial of permissions in accordance
  452. * with the policy. This function is typically called by
  453. * avc_has_perm() after a permission check, but can also be
  454. * called directly by callers who use avc_has_perm_noaudit()
  455. * in order to separate the permission check from the auditing.
  456. * For example, this separation is useful when the permission check must
  457. * be performed under a lock, to allow the lock to be released
  458. * before calling the auditing code.
  459. */
  460. void avc_audit(u32 ssid, u32 tsid,
  461. u16 tclass, u32 requested,
  462. struct av_decision *avd, int result, struct avc_audit_data *a)
  463. {
  464. struct task_struct *tsk = current;
  465. struct inode *inode = NULL;
  466. u32 denied, audited;
  467. struct audit_buffer *ab;
  468. denied = requested & ~avd->allowed;
  469. if (denied) {
  470. audited = denied;
  471. if (!(audited & avd->auditdeny))
  472. return;
  473. } else if (result) {
  474. audited = denied = requested;
  475. } else {
  476. audited = requested;
  477. if (!(audited & avd->auditallow))
  478. return;
  479. }
  480. ab = audit_log_start(current->audit_context, GFP_ATOMIC, AUDIT_AVC);
  481. if (!ab)
  482. return; /* audit_panic has been called */
  483. audit_log_format(ab, "avc: %s ", denied ? "denied" : "granted");
  484. avc_dump_av(ab, tclass,audited);
  485. audit_log_format(ab, " for ");
  486. if (a && a->tsk)
  487. tsk = a->tsk;
  488. if (tsk && tsk->pid) {
  489. audit_log_format(ab, " pid=%d comm=", tsk->pid);
  490. audit_log_untrustedstring(ab, tsk->comm);
  491. }
  492. if (a) {
  493. switch (a->type) {
  494. case AVC_AUDIT_DATA_IPC:
  495. audit_log_format(ab, " key=%d", a->u.ipc_id);
  496. break;
  497. case AVC_AUDIT_DATA_CAP:
  498. audit_log_format(ab, " capability=%d", a->u.cap);
  499. break;
  500. case AVC_AUDIT_DATA_FS:
  501. if (a->u.fs.dentry) {
  502. struct dentry *dentry = a->u.fs.dentry;
  503. if (a->u.fs.mnt)
  504. audit_avc_path(dentry, a->u.fs.mnt);
  505. audit_log_format(ab, " name=");
  506. audit_log_untrustedstring(ab, dentry->d_name.name);
  507. inode = dentry->d_inode;
  508. } else if (a->u.fs.inode) {
  509. struct dentry *dentry;
  510. inode = a->u.fs.inode;
  511. dentry = d_find_alias(inode);
  512. if (dentry) {
  513. audit_log_format(ab, " name=");
  514. audit_log_untrustedstring(ab, dentry->d_name.name);
  515. dput(dentry);
  516. }
  517. }
  518. if (inode)
  519. audit_log_format(ab, " dev=%s ino=%ld",
  520. inode->i_sb->s_id,
  521. inode->i_ino);
  522. break;
  523. case AVC_AUDIT_DATA_NET:
  524. if (a->u.net.sk) {
  525. struct sock *sk = a->u.net.sk;
  526. struct unix_sock *u;
  527. int len = 0;
  528. char *p = NULL;
  529. switch (sk->sk_family) {
  530. case AF_INET: {
  531. struct inet_sock *inet = inet_sk(sk);
  532. avc_print_ipv4_addr(ab, inet->rcv_saddr,
  533. inet->sport,
  534. "laddr", "lport");
  535. avc_print_ipv4_addr(ab, inet->daddr,
  536. inet->dport,
  537. "faddr", "fport");
  538. break;
  539. }
  540. case AF_INET6: {
  541. struct inet_sock *inet = inet_sk(sk);
  542. struct ipv6_pinfo *inet6 = inet6_sk(sk);
  543. avc_print_ipv6_addr(ab, &inet6->rcv_saddr,
  544. inet->sport,
  545. "laddr", "lport");
  546. avc_print_ipv6_addr(ab, &inet6->daddr,
  547. inet->dport,
  548. "faddr", "fport");
  549. break;
  550. }
  551. case AF_UNIX:
  552. u = unix_sk(sk);
  553. if (u->dentry) {
  554. audit_avc_path(u->dentry, u->mnt);
  555. audit_log_format(ab, " name=");
  556. audit_log_untrustedstring(ab, u->dentry->d_name.name);
  557. break;
  558. }
  559. if (!u->addr)
  560. break;
  561. len = u->addr->len-sizeof(short);
  562. p = &u->addr->name->sun_path[0];
  563. audit_log_format(ab, " path=");
  564. if (*p)
  565. audit_log_untrustedstring(ab, p);
  566. else
  567. audit_log_hex(ab, p, len);
  568. break;
  569. }
  570. }
  571. switch (a->u.net.family) {
  572. case AF_INET:
  573. avc_print_ipv4_addr(ab, a->u.net.v4info.saddr,
  574. a->u.net.sport,
  575. "saddr", "src");
  576. avc_print_ipv4_addr(ab, a->u.net.v4info.daddr,
  577. a->u.net.dport,
  578. "daddr", "dest");
  579. break;
  580. case AF_INET6:
  581. avc_print_ipv6_addr(ab, &a->u.net.v6info.saddr,
  582. a->u.net.sport,
  583. "saddr", "src");
  584. avc_print_ipv6_addr(ab, &a->u.net.v6info.daddr,
  585. a->u.net.dport,
  586. "daddr", "dest");
  587. break;
  588. }
  589. if (a->u.net.netif)
  590. audit_log_format(ab, " netif=%s",
  591. a->u.net.netif);
  592. break;
  593. }
  594. }
  595. audit_log_format(ab, " ");
  596. avc_dump_query(ab, ssid, tsid, tclass);
  597. audit_log_end(ab);
  598. }
  599. /**
  600. * avc_add_callback - Register a callback for security events.
  601. * @callback: callback function
  602. * @events: security events
  603. * @ssid: source security identifier or %SECSID_WILD
  604. * @tsid: target security identifier or %SECSID_WILD
  605. * @tclass: target security class
  606. * @perms: permissions
  607. *
  608. * Register a callback function for events in the set @events
  609. * related to the SID pair (@ssid, @tsid) and
  610. * and the permissions @perms, interpreting
  611. * @perms based on @tclass. Returns %0 on success or
  612. * -%ENOMEM if insufficient memory exists to add the callback.
  613. */
  614. int avc_add_callback(int (*callback)(u32 event, u32 ssid, u32 tsid,
  615. u16 tclass, u32 perms,
  616. u32 *out_retained),
  617. u32 events, u32 ssid, u32 tsid,
  618. u16 tclass, u32 perms)
  619. {
  620. struct avc_callback_node *c;
  621. int rc = 0;
  622. c = kmalloc(sizeof(*c), GFP_ATOMIC);
  623. if (!c) {
  624. rc = -ENOMEM;
  625. goto out;
  626. }
  627. c->callback = callback;
  628. c->events = events;
  629. c->ssid = ssid;
  630. c->tsid = tsid;
  631. c->perms = perms;
  632. c->next = avc_callbacks;
  633. avc_callbacks = c;
  634. out:
  635. return rc;
  636. }
  637. static inline int avc_sidcmp(u32 x, u32 y)
  638. {
  639. return (x == y || x == SECSID_WILD || y == SECSID_WILD);
  640. }
  641. /**
  642. * avc_update_node Update an AVC entry
  643. * @event : Updating event
  644. * @perms : Permission mask bits
  645. * @ssid,@tsid,@tclass : identifier of an AVC entry
  646. *
  647. * if a valid AVC entry doesn't exist,this function returns -ENOENT.
  648. * if kmalloc() called internal returns NULL, this function returns -ENOMEM.
  649. * otherwise, this function update the AVC entry. The original AVC-entry object
  650. * will release later by RCU.
  651. */
  652. static int avc_update_node(u32 event, u32 perms, u32 ssid, u32 tsid, u16 tclass)
  653. {
  654. int hvalue, rc = 0;
  655. unsigned long flag;
  656. struct avc_node *pos, *node, *orig = NULL;
  657. node = avc_alloc_node();
  658. if (!node) {
  659. rc = -ENOMEM;
  660. goto out;
  661. }
  662. /* Lock the target slot */
  663. hvalue = avc_hash(ssid, tsid, tclass);
  664. spin_lock_irqsave(&avc_cache.slots_lock[hvalue], flag);
  665. list_for_each_entry(pos, &avc_cache.slots[hvalue], list){
  666. if ( ssid==pos->ae.ssid &&
  667. tsid==pos->ae.tsid &&
  668. tclass==pos->ae.tclass ){
  669. orig = pos;
  670. break;
  671. }
  672. }
  673. if (!orig) {
  674. rc = -ENOENT;
  675. avc_node_kill(node);
  676. goto out_unlock;
  677. }
  678. /*
  679. * Copy and replace original node.
  680. */
  681. avc_node_populate(node, ssid, tsid, tclass, &orig->ae);
  682. switch (event) {
  683. case AVC_CALLBACK_GRANT:
  684. node->ae.avd.allowed |= perms;
  685. break;
  686. case AVC_CALLBACK_TRY_REVOKE:
  687. case AVC_CALLBACK_REVOKE:
  688. node->ae.avd.allowed &= ~perms;
  689. break;
  690. case AVC_CALLBACK_AUDITALLOW_ENABLE:
  691. node->ae.avd.auditallow |= perms;
  692. break;
  693. case AVC_CALLBACK_AUDITALLOW_DISABLE:
  694. node->ae.avd.auditallow &= ~perms;
  695. break;
  696. case AVC_CALLBACK_AUDITDENY_ENABLE:
  697. node->ae.avd.auditdeny |= perms;
  698. break;
  699. case AVC_CALLBACK_AUDITDENY_DISABLE:
  700. node->ae.avd.auditdeny &= ~perms;
  701. break;
  702. }
  703. avc_node_replace(node, orig);
  704. out_unlock:
  705. spin_unlock_irqrestore(&avc_cache.slots_lock[hvalue], flag);
  706. out:
  707. return rc;
  708. }
  709. /**
  710. * avc_ss_reset - Flush the cache and revalidate migrated permissions.
  711. * @seqno: policy sequence number
  712. */
  713. int avc_ss_reset(u32 seqno)
  714. {
  715. struct avc_callback_node *c;
  716. int i, rc = 0, tmprc;
  717. unsigned long flag;
  718. struct avc_node *node;
  719. for (i = 0; i < AVC_CACHE_SLOTS; i++) {
  720. spin_lock_irqsave(&avc_cache.slots_lock[i], flag);
  721. list_for_each_entry(node, &avc_cache.slots[i], list)
  722. avc_node_delete(node);
  723. spin_unlock_irqrestore(&avc_cache.slots_lock[i], flag);
  724. }
  725. for (c = avc_callbacks; c; c = c->next) {
  726. if (c->events & AVC_CALLBACK_RESET) {
  727. tmprc = c->callback(AVC_CALLBACK_RESET,
  728. 0, 0, 0, 0, NULL);
  729. /* save the first error encountered for the return
  730. value and continue processing the callbacks */
  731. if (!rc)
  732. rc = tmprc;
  733. }
  734. }
  735. avc_latest_notif_update(seqno, 0);
  736. return rc;
  737. }
  738. /**
  739. * avc_has_perm_noaudit - Check permissions but perform no auditing.
  740. * @ssid: source security identifier
  741. * @tsid: target security identifier
  742. * @tclass: target security class
  743. * @requested: requested permissions, interpreted based on @tclass
  744. * @flags: AVC_STRICT or 0
  745. * @avd: access vector decisions
  746. *
  747. * Check the AVC to determine whether the @requested permissions are granted
  748. * for the SID pair (@ssid, @tsid), interpreting the permissions
  749. * based on @tclass, and call the security server on a cache miss to obtain
  750. * a new decision and add it to the cache. Return a copy of the decisions
  751. * in @avd. Return %0 if all @requested permissions are granted,
  752. * -%EACCES if any permissions are denied, or another -errno upon
  753. * other errors. This function is typically called by avc_has_perm(),
  754. * but may also be called directly to separate permission checking from
  755. * auditing, e.g. in cases where a lock must be held for the check but
  756. * should be released for the auditing.
  757. */
  758. int avc_has_perm_noaudit(u32 ssid, u32 tsid,
  759. u16 tclass, u32 requested,
  760. unsigned flags,
  761. struct av_decision *avd)
  762. {
  763. struct avc_node *node;
  764. struct avc_entry entry, *p_ae;
  765. int rc = 0;
  766. u32 denied;
  767. rcu_read_lock();
  768. node = avc_lookup(ssid, tsid, tclass, requested);
  769. if (!node) {
  770. rcu_read_unlock();
  771. rc = security_compute_av(ssid,tsid,tclass,requested,&entry.avd);
  772. if (rc)
  773. goto out;
  774. rcu_read_lock();
  775. node = avc_insert(ssid,tsid,tclass,&entry);
  776. }
  777. p_ae = node ? &node->ae : &entry;
  778. if (avd)
  779. memcpy(avd, &p_ae->avd, sizeof(*avd));
  780. denied = requested & ~(p_ae->avd.allowed);
  781. if (!requested || denied) {
  782. if (selinux_enforcing || (flags & AVC_STRICT))
  783. rc = -EACCES;
  784. else
  785. if (node)
  786. avc_update_node(AVC_CALLBACK_GRANT,requested,
  787. ssid,tsid,tclass);
  788. }
  789. rcu_read_unlock();
  790. out:
  791. return rc;
  792. }
  793. /**
  794. * avc_has_perm - Check permissions and perform any appropriate auditing.
  795. * @ssid: source security identifier
  796. * @tsid: target security identifier
  797. * @tclass: target security class
  798. * @requested: requested permissions, interpreted based on @tclass
  799. * @auditdata: auxiliary audit data
  800. *
  801. * Check the AVC to determine whether the @requested permissions are granted
  802. * for the SID pair (@ssid, @tsid), interpreting the permissions
  803. * based on @tclass, and call the security server on a cache miss to obtain
  804. * a new decision and add it to the cache. Audit the granting or denial of
  805. * permissions in accordance with the policy. Return %0 if all @requested
  806. * permissions are granted, -%EACCES if any permissions are denied, or
  807. * another -errno upon other errors.
  808. */
  809. int avc_has_perm(u32 ssid, u32 tsid, u16 tclass,
  810. u32 requested, struct avc_audit_data *auditdata)
  811. {
  812. struct av_decision avd;
  813. int rc;
  814. rc = avc_has_perm_noaudit(ssid, tsid, tclass, requested, 0, &avd);
  815. avc_audit(ssid, tsid, tclass, requested, &avd, rc, auditdata);
  816. return rc;
  817. }