| 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 | #include "classmap.h" |
| 35 | |
| 36 | #define AVC_CACHE_SLOTS 512 |
| 37 | #define AVC_DEF_CACHE_THRESHOLD 512 |
| 38 | #define AVC_CACHE_RECLAIM 16 |
| 39 | |
| 40 | #ifdef CONFIG_SECURITY_SELINUX_AVC_STATS |
| 41 | #define avc_cache_stats_incr(field) this_cpu_inc(avc_cache_stats.field) |
| 42 | #else |
| 43 | #define avc_cache_stats_incr(field) do {} while (0) |
| 44 | #endif |
| 45 | |
| 46 | struct avc_entry { |
| 47 | u32 ssid; |
| 48 | u32 tsid; |
| 49 | u16 tclass; |
| 50 | struct av_decision avd; |
| 51 | }; |
| 52 | |
| 53 | struct avc_node { |
| 54 | struct avc_entry ae; |
| 55 | struct hlist_node list; /* anchored in avc_cache->slots[i] */ |
| 56 | struct rcu_head rhead; |
| 57 | }; |
| 58 | |
| 59 | struct avc_cache { |
| 60 | struct hlist_head slots[AVC_CACHE_SLOTS]; /* head for avc_node->list */ |
| 61 | spinlock_t slots_lock[AVC_CACHE_SLOTS]; /* lock for writes */ |
| 62 | atomic_t lru_hint; /* LRU hint for reclaim scan */ |
| 63 | atomic_t active_nodes; |
| 64 | u32 latest_notif; /* latest revocation notification */ |
| 65 | }; |
| 66 | |
| 67 | struct avc_callback_node { |
| 68 | int (*callback) (u32 event); |
| 69 | u32 events; |
| 70 | struct avc_callback_node *next; |
| 71 | }; |
| 72 | |
| 73 | /* Exported via selinufs */ |
| 74 | unsigned int avc_cache_threshold = AVC_DEF_CACHE_THRESHOLD; |
| 75 | |
| 76 | #ifdef CONFIG_SECURITY_SELINUX_AVC_STATS |
| 77 | DEFINE_PER_CPU(struct avc_cache_stats, avc_cache_stats) = { 0 }; |
| 78 | #endif |
| 79 | |
| 80 | static struct avc_cache avc_cache; |
| 81 | static struct avc_callback_node *avc_callbacks; |
| 82 | static struct kmem_cache *avc_node_cachep; |
| 83 | |
| 84 | static inline int avc_hash(u32 ssid, u32 tsid, u16 tclass) |
| 85 | { |
| 86 | return (ssid ^ (tsid<<2) ^ (tclass<<4)) & (AVC_CACHE_SLOTS - 1); |
| 87 | } |
| 88 | |
| 89 | /** |
| 90 | * avc_dump_av - Display an access vector in human-readable form. |
| 91 | * @tclass: target security class |
| 92 | * @av: access vector |
| 93 | */ |
| 94 | static void avc_dump_av(struct audit_buffer *ab, u16 tclass, u32 av) |
| 95 | { |
| 96 | const char **perms; |
| 97 | int i, perm; |
| 98 | |
| 99 | if (av == 0) { |
| 100 | audit_log_format(ab, " null"); |
| 101 | return; |
| 102 | } |
| 103 | |
| 104 | perms = secclass_map[tclass-1].perms; |
| 105 | |
| 106 | audit_log_format(ab, " {"); |
| 107 | i = 0; |
| 108 | perm = 1; |
| 109 | while (i < (sizeof(av) * 8)) { |
| 110 | if ((perm & av) && perms[i]) { |
| 111 | audit_log_format(ab, " %s", perms[i]); |
| 112 | av &= ~perm; |
| 113 | } |
| 114 | i++; |
| 115 | perm <<= 1; |
| 116 | } |
| 117 | |
| 118 | if (av) |
| 119 | audit_log_format(ab, " 0x%x", av); |
| 120 | |
| 121 | audit_log_format(ab, " }"); |
| 122 | } |
| 123 | |
| 124 | /** |
| 125 | * avc_dump_query - Display a SID pair and a class in human-readable form. |
| 126 | * @ssid: source security identifier |
| 127 | * @tsid: target security identifier |
| 128 | * @tclass: target security class |
| 129 | */ |
| 130 | static void avc_dump_query(struct audit_buffer *ab, u32 ssid, u32 tsid, u16 tclass) |
| 131 | { |
| 132 | int rc; |
| 133 | char *scontext; |
| 134 | u32 scontext_len; |
| 135 | |
| 136 | rc = security_sid_to_context(ssid, &scontext, &scontext_len); |
| 137 | if (rc) |
| 138 | audit_log_format(ab, "ssid=%d", ssid); |
| 139 | else { |
| 140 | audit_log_format(ab, "scontext=%s", scontext); |
| 141 | kfree(scontext); |
| 142 | } |
| 143 | |
| 144 | rc = security_sid_to_context(tsid, &scontext, &scontext_len); |
| 145 | if (rc) |
| 146 | audit_log_format(ab, " tsid=%d", tsid); |
| 147 | else { |
| 148 | audit_log_format(ab, " tcontext=%s", scontext); |
| 149 | kfree(scontext); |
| 150 | } |
| 151 | |
| 152 | BUG_ON(tclass >= ARRAY_SIZE(secclass_map)); |
| 153 | audit_log_format(ab, " tclass=%s", secclass_map[tclass-1].name); |
| 154 | } |
| 155 | |
| 156 | /** |
| 157 | * avc_init - Initialize the AVC. |
| 158 | * |
| 159 | * Initialize the access vector cache. |
| 160 | */ |
| 161 | void __init avc_init(void) |
| 162 | { |
| 163 | int i; |
| 164 | |
| 165 | for (i = 0; i < AVC_CACHE_SLOTS; i++) { |
| 166 | INIT_HLIST_HEAD(&avc_cache.slots[i]); |
| 167 | spin_lock_init(&avc_cache.slots_lock[i]); |
| 168 | } |
| 169 | atomic_set(&avc_cache.active_nodes, 0); |
| 170 | atomic_set(&avc_cache.lru_hint, 0); |
| 171 | |
| 172 | avc_node_cachep = kmem_cache_create("avc_node", sizeof(struct avc_node), |
| 173 | 0, SLAB_PANIC, NULL); |
| 174 | |
| 175 | audit_log(current->audit_context, GFP_KERNEL, AUDIT_KERNEL, "AVC INITIALIZED\n"); |
| 176 | } |
| 177 | |
| 178 | int avc_get_hash_stats(char *page) |
| 179 | { |
| 180 | int i, chain_len, max_chain_len, slots_used; |
| 181 | struct avc_node *node; |
| 182 | struct hlist_head *head; |
| 183 | |
| 184 | rcu_read_lock(); |
| 185 | |
| 186 | slots_used = 0; |
| 187 | max_chain_len = 0; |
| 188 | for (i = 0; i < AVC_CACHE_SLOTS; i++) { |
| 189 | head = &avc_cache.slots[i]; |
| 190 | if (!hlist_empty(head)) { |
| 191 | slots_used++; |
| 192 | chain_len = 0; |
| 193 | hlist_for_each_entry_rcu(node, head, list) |
| 194 | chain_len++; |
| 195 | if (chain_len > max_chain_len) |
| 196 | max_chain_len = chain_len; |
| 197 | } |
| 198 | } |
| 199 | |
| 200 | rcu_read_unlock(); |
| 201 | |
| 202 | return scnprintf(page, PAGE_SIZE, "entries: %d\nbuckets used: %d/%d\n" |
| 203 | "longest chain: %d\n", |
| 204 | atomic_read(&avc_cache.active_nodes), |
| 205 | slots_used, AVC_CACHE_SLOTS, max_chain_len); |
| 206 | } |
| 207 | |
| 208 | static void avc_node_free(struct rcu_head *rhead) |
| 209 | { |
| 210 | struct avc_node *node = container_of(rhead, struct avc_node, rhead); |
| 211 | kmem_cache_free(avc_node_cachep, node); |
| 212 | avc_cache_stats_incr(frees); |
| 213 | } |
| 214 | |
| 215 | static void avc_node_delete(struct avc_node *node) |
| 216 | { |
| 217 | hlist_del_rcu(&node->list); |
| 218 | call_rcu(&node->rhead, avc_node_free); |
| 219 | atomic_dec(&avc_cache.active_nodes); |
| 220 | } |
| 221 | |
| 222 | static void avc_node_kill(struct avc_node *node) |
| 223 | { |
| 224 | kmem_cache_free(avc_node_cachep, node); |
| 225 | avc_cache_stats_incr(frees); |
| 226 | atomic_dec(&avc_cache.active_nodes); |
| 227 | } |
| 228 | |
| 229 | static void avc_node_replace(struct avc_node *new, struct avc_node *old) |
| 230 | { |
| 231 | hlist_replace_rcu(&old->list, &new->list); |
| 232 | call_rcu(&old->rhead, avc_node_free); |
| 233 | atomic_dec(&avc_cache.active_nodes); |
| 234 | } |
| 235 | |
| 236 | static inline int avc_reclaim_node(void) |
| 237 | { |
| 238 | struct avc_node *node; |
| 239 | int hvalue, try, ecx; |
| 240 | unsigned long flags; |
| 241 | struct hlist_head *head; |
| 242 | spinlock_t *lock; |
| 243 | |
| 244 | for (try = 0, ecx = 0; try < AVC_CACHE_SLOTS; try++) { |
| 245 | hvalue = atomic_inc_return(&avc_cache.lru_hint) & (AVC_CACHE_SLOTS - 1); |
| 246 | head = &avc_cache.slots[hvalue]; |
| 247 | lock = &avc_cache.slots_lock[hvalue]; |
| 248 | |
| 249 | if (!spin_trylock_irqsave(lock, flags)) |
| 250 | continue; |
| 251 | |
| 252 | rcu_read_lock(); |
| 253 | hlist_for_each_entry(node, head, list) { |
| 254 | avc_node_delete(node); |
| 255 | avc_cache_stats_incr(reclaims); |
| 256 | ecx++; |
| 257 | if (ecx >= AVC_CACHE_RECLAIM) { |
| 258 | rcu_read_unlock(); |
| 259 | spin_unlock_irqrestore(lock, flags); |
| 260 | goto out; |
| 261 | } |
| 262 | } |
| 263 | rcu_read_unlock(); |
| 264 | spin_unlock_irqrestore(lock, flags); |
| 265 | } |
| 266 | out: |
| 267 | return ecx; |
| 268 | } |
| 269 | |
| 270 | static struct avc_node *avc_alloc_node(void) |
| 271 | { |
| 272 | struct avc_node *node; |
| 273 | |
| 274 | node = kmem_cache_zalloc(avc_node_cachep, GFP_ATOMIC|__GFP_NOMEMALLOC); |
| 275 | if (!node) |
| 276 | goto out; |
| 277 | |
| 278 | INIT_HLIST_NODE(&node->list); |
| 279 | avc_cache_stats_incr(allocations); |
| 280 | |
| 281 | if (atomic_inc_return(&avc_cache.active_nodes) > avc_cache_threshold) |
| 282 | avc_reclaim_node(); |
| 283 | |
| 284 | out: |
| 285 | return node; |
| 286 | } |
| 287 | |
| 288 | static void avc_node_populate(struct avc_node *node, u32 ssid, u32 tsid, u16 tclass, struct av_decision *avd) |
| 289 | { |
| 290 | node->ae.ssid = ssid; |
| 291 | node->ae.tsid = tsid; |
| 292 | node->ae.tclass = tclass; |
| 293 | memcpy(&node->ae.avd, avd, sizeof(node->ae.avd)); |
| 294 | } |
| 295 | |
| 296 | static inline struct avc_node *avc_search_node(u32 ssid, u32 tsid, u16 tclass) |
| 297 | { |
| 298 | struct avc_node *node, *ret = NULL; |
| 299 | int hvalue; |
| 300 | struct hlist_head *head; |
| 301 | |
| 302 | hvalue = avc_hash(ssid, tsid, tclass); |
| 303 | head = &avc_cache.slots[hvalue]; |
| 304 | hlist_for_each_entry_rcu(node, head, list) { |
| 305 | if (ssid == node->ae.ssid && |
| 306 | tclass == node->ae.tclass && |
| 307 | tsid == node->ae.tsid) { |
| 308 | ret = node; |
| 309 | break; |
| 310 | } |
| 311 | } |
| 312 | |
| 313 | return ret; |
| 314 | } |
| 315 | |
| 316 | /** |
| 317 | * avc_lookup - Look up an AVC entry. |
| 318 | * @ssid: source security identifier |
| 319 | * @tsid: target security identifier |
| 320 | * @tclass: target security class |
| 321 | * |
| 322 | * Look up an AVC entry that is valid for the |
| 323 | * (@ssid, @tsid), interpreting the permissions |
| 324 | * based on @tclass. If a valid AVC entry exists, |
| 325 | * then this function returns the avc_node. |
| 326 | * Otherwise, this function returns NULL. |
| 327 | */ |
| 328 | static struct avc_node *avc_lookup(u32 ssid, u32 tsid, u16 tclass) |
| 329 | { |
| 330 | struct avc_node *node; |
| 331 | |
| 332 | avc_cache_stats_incr(lookups); |
| 333 | node = avc_search_node(ssid, tsid, tclass); |
| 334 | |
| 335 | if (node) |
| 336 | return node; |
| 337 | |
| 338 | avc_cache_stats_incr(misses); |
| 339 | return NULL; |
| 340 | } |
| 341 | |
| 342 | static int avc_latest_notif_update(int seqno, int is_insert) |
| 343 | { |
| 344 | int ret = 0; |
| 345 | static DEFINE_SPINLOCK(notif_lock); |
| 346 | unsigned long flag; |
| 347 | |
| 348 | spin_lock_irqsave(¬if_lock, flag); |
| 349 | if (is_insert) { |
| 350 | if (seqno < avc_cache.latest_notif) { |
| 351 | printk(KERN_WARNING "SELinux: avc: seqno %d < latest_notif %d\n", |
| 352 | seqno, avc_cache.latest_notif); |
| 353 | ret = -EAGAIN; |
| 354 | } |
| 355 | } else { |
| 356 | if (seqno > avc_cache.latest_notif) |
| 357 | avc_cache.latest_notif = seqno; |
| 358 | } |
| 359 | spin_unlock_irqrestore(¬if_lock, flag); |
| 360 | |
| 361 | return ret; |
| 362 | } |
| 363 | |
| 364 | /** |
| 365 | * avc_insert - Insert an AVC entry. |
| 366 | * @ssid: source security identifier |
| 367 | * @tsid: target security identifier |
| 368 | * @tclass: target security class |
| 369 | * @avd: resulting av decision |
| 370 | * |
| 371 | * Insert an AVC entry for the SID pair |
| 372 | * (@ssid, @tsid) and class @tclass. |
| 373 | * The access vectors and the sequence number are |
| 374 | * normally provided by the security server in |
| 375 | * response to a security_compute_av() call. If the |
| 376 | * sequence number @avd->seqno is not less than the latest |
| 377 | * revocation notification, then the function copies |
| 378 | * the access vectors into a cache entry, returns |
| 379 | * avc_node inserted. Otherwise, this function returns NULL. |
| 380 | */ |
| 381 | static struct avc_node *avc_insert(u32 ssid, u32 tsid, u16 tclass, struct av_decision *avd) |
| 382 | { |
| 383 | struct avc_node *pos, *node = NULL; |
| 384 | int hvalue; |
| 385 | unsigned long flag; |
| 386 | |
| 387 | if (avc_latest_notif_update(avd->seqno, 1)) |
| 388 | goto out; |
| 389 | |
| 390 | node = avc_alloc_node(); |
| 391 | if (node) { |
| 392 | struct hlist_head *head; |
| 393 | spinlock_t *lock; |
| 394 | |
| 395 | hvalue = avc_hash(ssid, tsid, tclass); |
| 396 | avc_node_populate(node, ssid, tsid, tclass, avd); |
| 397 | |
| 398 | head = &avc_cache.slots[hvalue]; |
| 399 | lock = &avc_cache.slots_lock[hvalue]; |
| 400 | |
| 401 | spin_lock_irqsave(lock, flag); |
| 402 | hlist_for_each_entry(pos, head, list) { |
| 403 | if (pos->ae.ssid == ssid && |
| 404 | pos->ae.tsid == tsid && |
| 405 | pos->ae.tclass == tclass) { |
| 406 | avc_node_replace(node, pos); |
| 407 | goto found; |
| 408 | } |
| 409 | } |
| 410 | hlist_add_head_rcu(&node->list, head); |
| 411 | found: |
| 412 | spin_unlock_irqrestore(lock, flag); |
| 413 | } |
| 414 | out: |
| 415 | return node; |
| 416 | } |
| 417 | |
| 418 | /** |
| 419 | * avc_audit_pre_callback - SELinux specific information |
| 420 | * will be called by generic audit code |
| 421 | * @ab: the audit buffer |
| 422 | * @a: audit_data |
| 423 | */ |
| 424 | static void avc_audit_pre_callback(struct audit_buffer *ab, void *a) |
| 425 | { |
| 426 | struct common_audit_data *ad = a; |
| 427 | audit_log_format(ab, "avc: %s ", |
| 428 | ad->selinux_audit_data->denied ? "denied" : "granted"); |
| 429 | avc_dump_av(ab, ad->selinux_audit_data->tclass, |
| 430 | ad->selinux_audit_data->audited); |
| 431 | audit_log_format(ab, " for "); |
| 432 | } |
| 433 | |
| 434 | /** |
| 435 | * avc_audit_post_callback - SELinux specific information |
| 436 | * will be called by generic audit code |
| 437 | * @ab: the audit buffer |
| 438 | * @a: audit_data |
| 439 | */ |
| 440 | static void avc_audit_post_callback(struct audit_buffer *ab, void *a) |
| 441 | { |
| 442 | struct common_audit_data *ad = a; |
| 443 | audit_log_format(ab, " "); |
| 444 | avc_dump_query(ab, ad->selinux_audit_data->ssid, |
| 445 | ad->selinux_audit_data->tsid, |
| 446 | ad->selinux_audit_data->tclass); |
| 447 | if (ad->selinux_audit_data->denied) { |
| 448 | audit_log_format(ab, " permissive=%u", |
| 449 | ad->selinux_audit_data->result ? 0 : 1); |
| 450 | } |
| 451 | } |
| 452 | |
| 453 | /* This is the slow part of avc audit with big stack footprint */ |
| 454 | noinline int slow_avc_audit(u32 ssid, u32 tsid, u16 tclass, |
| 455 | u32 requested, u32 audited, u32 denied, int result, |
| 456 | struct common_audit_data *a, |
| 457 | unsigned flags) |
| 458 | { |
| 459 | struct common_audit_data stack_data; |
| 460 | struct selinux_audit_data sad; |
| 461 | |
| 462 | if (!a) { |
| 463 | a = &stack_data; |
| 464 | a->type = LSM_AUDIT_DATA_NONE; |
| 465 | } |
| 466 | |
| 467 | /* |
| 468 | * When in a RCU walk do the audit on the RCU retry. This is because |
| 469 | * the collection of the dname in an inode audit message is not RCU |
| 470 | * safe. Note this may drop some audits when the situation changes |
| 471 | * during retry. However this is logically just as if the operation |
| 472 | * happened a little later. |
| 473 | */ |
| 474 | if ((a->type == LSM_AUDIT_DATA_INODE) && |
| 475 | (flags & MAY_NOT_BLOCK)) |
| 476 | return -ECHILD; |
| 477 | |
| 478 | sad.tclass = tclass; |
| 479 | sad.requested = requested; |
| 480 | sad.ssid = ssid; |
| 481 | sad.tsid = tsid; |
| 482 | sad.audited = audited; |
| 483 | sad.denied = denied; |
| 484 | sad.result = result; |
| 485 | |
| 486 | a->selinux_audit_data = &sad; |
| 487 | |
| 488 | common_lsm_audit(a, avc_audit_pre_callback, avc_audit_post_callback); |
| 489 | return 0; |
| 490 | } |
| 491 | |
| 492 | /** |
| 493 | * avc_add_callback - Register a callback for security events. |
| 494 | * @callback: callback function |
| 495 | * @events: security events |
| 496 | * |
| 497 | * Register a callback function for events in the set @events. |
| 498 | * Returns %0 on success or -%ENOMEM if insufficient memory |
| 499 | * exists to add the callback. |
| 500 | */ |
| 501 | int __init avc_add_callback(int (*callback)(u32 event), u32 events) |
| 502 | { |
| 503 | struct avc_callback_node *c; |
| 504 | int rc = 0; |
| 505 | |
| 506 | c = kmalloc(sizeof(*c), GFP_KERNEL); |
| 507 | if (!c) { |
| 508 | rc = -ENOMEM; |
| 509 | goto out; |
| 510 | } |
| 511 | |
| 512 | c->callback = callback; |
| 513 | c->events = events; |
| 514 | c->next = avc_callbacks; |
| 515 | avc_callbacks = c; |
| 516 | out: |
| 517 | return rc; |
| 518 | } |
| 519 | |
| 520 | /** |
| 521 | * avc_update_node Update an AVC entry |
| 522 | * @event : Updating event |
| 523 | * @perms : Permission mask bits |
| 524 | * @ssid,@tsid,@tclass : identifier of an AVC entry |
| 525 | * @seqno : sequence number when decision was made |
| 526 | * |
| 527 | * if a valid AVC entry doesn't exist,this function returns -ENOENT. |
| 528 | * if kmalloc() called internal returns NULL, this function returns -ENOMEM. |
| 529 | * otherwise, this function updates the AVC entry. The original AVC-entry object |
| 530 | * will release later by RCU. |
| 531 | */ |
| 532 | static int avc_update_node(u32 event, u32 perms, u32 ssid, u32 tsid, u16 tclass, |
| 533 | u32 seqno) |
| 534 | { |
| 535 | int hvalue, rc = 0; |
| 536 | unsigned long flag; |
| 537 | struct avc_node *pos, *node, *orig = NULL; |
| 538 | struct hlist_head *head; |
| 539 | spinlock_t *lock; |
| 540 | |
| 541 | node = avc_alloc_node(); |
| 542 | if (!node) { |
| 543 | rc = -ENOMEM; |
| 544 | goto out; |
| 545 | } |
| 546 | |
| 547 | /* Lock the target slot */ |
| 548 | hvalue = avc_hash(ssid, tsid, tclass); |
| 549 | |
| 550 | head = &avc_cache.slots[hvalue]; |
| 551 | lock = &avc_cache.slots_lock[hvalue]; |
| 552 | |
| 553 | spin_lock_irqsave(lock, flag); |
| 554 | |
| 555 | hlist_for_each_entry(pos, head, list) { |
| 556 | if (ssid == pos->ae.ssid && |
| 557 | tsid == pos->ae.tsid && |
| 558 | tclass == pos->ae.tclass && |
| 559 | seqno == pos->ae.avd.seqno){ |
| 560 | orig = pos; |
| 561 | break; |
| 562 | } |
| 563 | } |
| 564 | |
| 565 | if (!orig) { |
| 566 | rc = -ENOENT; |
| 567 | avc_node_kill(node); |
| 568 | goto out_unlock; |
| 569 | } |
| 570 | |
| 571 | /* |
| 572 | * Copy and replace original node. |
| 573 | */ |
| 574 | |
| 575 | avc_node_populate(node, ssid, tsid, tclass, &orig->ae.avd); |
| 576 | |
| 577 | switch (event) { |
| 578 | case AVC_CALLBACK_GRANT: |
| 579 | node->ae.avd.allowed |= perms; |
| 580 | break; |
| 581 | case AVC_CALLBACK_TRY_REVOKE: |
| 582 | case AVC_CALLBACK_REVOKE: |
| 583 | node->ae.avd.allowed &= ~perms; |
| 584 | break; |
| 585 | case AVC_CALLBACK_AUDITALLOW_ENABLE: |
| 586 | node->ae.avd.auditallow |= perms; |
| 587 | break; |
| 588 | case AVC_CALLBACK_AUDITALLOW_DISABLE: |
| 589 | node->ae.avd.auditallow &= ~perms; |
| 590 | break; |
| 591 | case AVC_CALLBACK_AUDITDENY_ENABLE: |
| 592 | node->ae.avd.auditdeny |= perms; |
| 593 | break; |
| 594 | case AVC_CALLBACK_AUDITDENY_DISABLE: |
| 595 | node->ae.avd.auditdeny &= ~perms; |
| 596 | break; |
| 597 | } |
| 598 | avc_node_replace(node, orig); |
| 599 | out_unlock: |
| 600 | spin_unlock_irqrestore(lock, flag); |
| 601 | out: |
| 602 | return rc; |
| 603 | } |
| 604 | |
| 605 | /** |
| 606 | * avc_flush - Flush the cache |
| 607 | */ |
| 608 | static void avc_flush(void) |
| 609 | { |
| 610 | struct hlist_head *head; |
| 611 | struct avc_node *node; |
| 612 | spinlock_t *lock; |
| 613 | unsigned long flag; |
| 614 | int i; |
| 615 | |
| 616 | for (i = 0; i < AVC_CACHE_SLOTS; i++) { |
| 617 | head = &avc_cache.slots[i]; |
| 618 | lock = &avc_cache.slots_lock[i]; |
| 619 | |
| 620 | spin_lock_irqsave(lock, flag); |
| 621 | /* |
| 622 | * With preemptable RCU, the outer spinlock does not |
| 623 | * prevent RCU grace periods from ending. |
| 624 | */ |
| 625 | rcu_read_lock(); |
| 626 | hlist_for_each_entry(node, head, list) |
| 627 | avc_node_delete(node); |
| 628 | rcu_read_unlock(); |
| 629 | spin_unlock_irqrestore(lock, flag); |
| 630 | } |
| 631 | } |
| 632 | |
| 633 | /** |
| 634 | * avc_ss_reset - Flush the cache and revalidate migrated permissions. |
| 635 | * @seqno: policy sequence number |
| 636 | */ |
| 637 | int avc_ss_reset(u32 seqno) |
| 638 | { |
| 639 | struct avc_callback_node *c; |
| 640 | int rc = 0, tmprc; |
| 641 | |
| 642 | avc_flush(); |
| 643 | |
| 644 | for (c = avc_callbacks; c; c = c->next) { |
| 645 | if (c->events & AVC_CALLBACK_RESET) { |
| 646 | tmprc = c->callback(AVC_CALLBACK_RESET); |
| 647 | /* save the first error encountered for the return |
| 648 | value and continue processing the callbacks */ |
| 649 | if (!rc) |
| 650 | rc = tmprc; |
| 651 | } |
| 652 | } |
| 653 | |
| 654 | avc_latest_notif_update(seqno, 0); |
| 655 | return rc; |
| 656 | } |
| 657 | |
| 658 | /* |
| 659 | * Slow-path helper function for avc_has_perm_noaudit, |
| 660 | * when the avc_node lookup fails. We get called with |
| 661 | * the RCU read lock held, and need to return with it |
| 662 | * still held, but drop if for the security compute. |
| 663 | * |
| 664 | * Don't inline this, since it's the slow-path and just |
| 665 | * results in a bigger stack frame. |
| 666 | */ |
| 667 | static noinline struct avc_node *avc_compute_av(u32 ssid, u32 tsid, |
| 668 | u16 tclass, struct av_decision *avd) |
| 669 | { |
| 670 | rcu_read_unlock(); |
| 671 | security_compute_av(ssid, tsid, tclass, avd); |
| 672 | rcu_read_lock(); |
| 673 | return avc_insert(ssid, tsid, tclass, avd); |
| 674 | } |
| 675 | |
| 676 | static noinline int avc_denied(u32 ssid, u32 tsid, |
| 677 | u16 tclass, u32 requested, |
| 678 | unsigned flags, |
| 679 | struct av_decision *avd) |
| 680 | { |
| 681 | if (flags & AVC_STRICT) |
| 682 | return -EACCES; |
| 683 | |
| 684 | if (selinux_enforcing && !(avd->flags & AVD_FLAGS_PERMISSIVE)) |
| 685 | return -EACCES; |
| 686 | |
| 687 | avc_update_node(AVC_CALLBACK_GRANT, requested, ssid, |
| 688 | tsid, tclass, avd->seqno); |
| 689 | return 0; |
| 690 | } |
| 691 | |
| 692 | |
| 693 | /** |
| 694 | * avc_has_perm_noaudit - Check permissions but perform no auditing. |
| 695 | * @ssid: source security identifier |
| 696 | * @tsid: target security identifier |
| 697 | * @tclass: target security class |
| 698 | * @requested: requested permissions, interpreted based on @tclass |
| 699 | * @flags: AVC_STRICT or 0 |
| 700 | * @avd: access vector decisions |
| 701 | * |
| 702 | * Check the AVC to determine whether the @requested permissions are granted |
| 703 | * for the SID pair (@ssid, @tsid), interpreting the permissions |
| 704 | * based on @tclass, and call the security server on a cache miss to obtain |
| 705 | * a new decision and add it to the cache. Return a copy of the decisions |
| 706 | * in @avd. Return %0 if all @requested permissions are granted, |
| 707 | * -%EACCES if any permissions are denied, or another -errno upon |
| 708 | * other errors. This function is typically called by avc_has_perm(), |
| 709 | * but may also be called directly to separate permission checking from |
| 710 | * auditing, e.g. in cases where a lock must be held for the check but |
| 711 | * should be released for the auditing. |
| 712 | */ |
| 713 | inline int avc_has_perm_noaudit(u32 ssid, u32 tsid, |
| 714 | u16 tclass, u32 requested, |
| 715 | unsigned flags, |
| 716 | struct av_decision *avd) |
| 717 | { |
| 718 | struct avc_node *node; |
| 719 | int rc = 0; |
| 720 | u32 denied; |
| 721 | |
| 722 | BUG_ON(!requested); |
| 723 | |
| 724 | rcu_read_lock(); |
| 725 | |
| 726 | node = avc_lookup(ssid, tsid, tclass); |
| 727 | if (unlikely(!node)) |
| 728 | node = avc_compute_av(ssid, tsid, tclass, avd); |
| 729 | else |
| 730 | memcpy(avd, &node->ae.avd, sizeof(*avd)); |
| 731 | |
| 732 | denied = requested & ~(avd->allowed); |
| 733 | if (unlikely(denied)) |
| 734 | rc = avc_denied(ssid, tsid, tclass, requested, flags, avd); |
| 735 | |
| 736 | rcu_read_unlock(); |
| 737 | return rc; |
| 738 | } |
| 739 | |
| 740 | /** |
| 741 | * avc_has_perm - Check permissions and perform any appropriate auditing. |
| 742 | * @ssid: source security identifier |
| 743 | * @tsid: target security identifier |
| 744 | * @tclass: target security class |
| 745 | * @requested: requested permissions, interpreted based on @tclass |
| 746 | * @auditdata: auxiliary audit data |
| 747 | * |
| 748 | * Check the AVC to determine whether the @requested permissions are granted |
| 749 | * for the SID pair (@ssid, @tsid), interpreting the permissions |
| 750 | * based on @tclass, and call the security server on a cache miss to obtain |
| 751 | * a new decision and add it to the cache. Audit the granting or denial of |
| 752 | * permissions in accordance with the policy. Return %0 if all @requested |
| 753 | * permissions are granted, -%EACCES if any permissions are denied, or |
| 754 | * another -errno upon other errors. |
| 755 | */ |
| 756 | int avc_has_perm(u32 ssid, u32 tsid, u16 tclass, |
| 757 | u32 requested, struct common_audit_data *auditdata) |
| 758 | { |
| 759 | struct av_decision avd; |
| 760 | int rc, rc2; |
| 761 | |
| 762 | rc = avc_has_perm_noaudit(ssid, tsid, tclass, requested, 0, &avd); |
| 763 | |
| 764 | rc2 = avc_audit(ssid, tsid, tclass, requested, &avd, rc, auditdata, 0); |
| 765 | if (rc2) |
| 766 | return rc2; |
| 767 | return rc; |
| 768 | } |
| 769 | |
| 770 | int avc_has_perm_flags(u32 ssid, u32 tsid, u16 tclass, |
| 771 | u32 requested, struct common_audit_data *auditdata, |
| 772 | int flags) |
| 773 | { |
| 774 | struct av_decision avd; |
| 775 | int rc, rc2; |
| 776 | |
| 777 | rc = avc_has_perm_noaudit(ssid, tsid, tclass, requested, 0, &avd); |
| 778 | |
| 779 | rc2 = avc_audit(ssid, tsid, tclass, requested, &avd, rc, |
| 780 | auditdata, flags); |
| 781 | if (rc2) |
| 782 | return rc2; |
| 783 | return rc; |
| 784 | } |
| 785 | |
| 786 | u32 avc_policy_seqno(void) |
| 787 | { |
| 788 | return avc_cache.latest_notif; |
| 789 | } |
| 790 | |
| 791 | void avc_disable(void) |
| 792 | { |
| 793 | /* |
| 794 | * If you are looking at this because you have realized that we are |
| 795 | * not destroying the avc_node_cachep it might be easy to fix, but |
| 796 | * I don't know the memory barrier semantics well enough to know. It's |
| 797 | * possible that some other task dereferenced security_ops when |
| 798 | * it still pointed to selinux operations. If that is the case it's |
| 799 | * possible that it is about to use the avc and is about to need the |
| 800 | * avc_node_cachep. I know I could wrap the security.c security_ops call |
| 801 | * in an rcu_lock, but seriously, it's not worth it. Instead I just flush |
| 802 | * the cache and get that memory back. |
| 803 | */ |
| 804 | if (avc_node_cachep) { |
| 805 | avc_flush(); |
| 806 | /* kmem_cache_destroy(avc_node_cachep); */ |
| 807 | } |
| 808 | } |