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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Implementation of the SID table type.
4 *
5 * Original author: Stephen Smalley, <sds@tycho.nsa.gov>
6 * Author: Ondrej Mosnacek, <omosnacek@gmail.com>
7 *
8 * Copyright (C) 2018 Red Hat, Inc.
9 */
10#include <linux/errno.h>
11#include <linux/kernel.h>
12#include <linux/list.h>
13#include <linux/rcupdate.h>
14#include <linux/slab.h>
15#include <linux/sched.h>
16#include <linux/spinlock.h>
17#include <asm/barrier.h>
18#include "flask.h"
19#include "security.h"
20#include "sidtab.h"
21#include "services.h"
22
23struct sidtab_str_cache {
24 struct rcu_head rcu_member;
25 struct list_head lru_member;
26 struct sidtab_entry *parent;
27 u32 len;
28 char str[];
29};
30
31#define index_to_sid(index) ((index) + SECINITSID_NUM + 1)
32#define sid_to_index(sid) ((sid) - (SECINITSID_NUM + 1))
33
34int sidtab_init(struct sidtab *s)
35{
36 u32 i;
37
38 memset(s->roots, 0, sizeof(s->roots));
39
40 for (i = 0; i < SECINITSID_NUM; i++)
41 s->isids[i].set = 0;
42
43 s->frozen = false;
44 s->count = 0;
45 s->convert = NULL;
46 hash_init(s->context_to_sid);
47
48 spin_lock_init(&s->lock);
49
50#if CONFIG_SECURITY_SELINUX_SID2STR_CACHE_SIZE > 0
51 s->cache_free_slots = CONFIG_SECURITY_SELINUX_SID2STR_CACHE_SIZE;
52 INIT_LIST_HEAD(&s->cache_lru_list);
53 spin_lock_init(&s->cache_lock);
54#endif
55
56 return 0;
57}
58
59static u32 context_to_sid(struct sidtab *s, struct context *context, u32 hash)
60{
61 struct sidtab_entry *entry;
62 u32 sid = 0;
63
64 rcu_read_lock();
65 hash_for_each_possible_rcu(s->context_to_sid, entry, list, hash) {
66 if (entry->hash != hash)
67 continue;
68 if (context_cmp(&entry->context, context)) {
69 sid = entry->sid;
70 break;
71 }
72 }
73 rcu_read_unlock();
74 return sid;
75}
76
77int sidtab_set_initial(struct sidtab *s, u32 sid, struct context *context)
78{
79 struct sidtab_isid_entry *isid;
80 u32 hash;
81 int rc;
82
83 if (sid == 0 || sid > SECINITSID_NUM)
84 return -EINVAL;
85
86 isid = &s->isids[sid - 1];
87
88 rc = context_cpy(&isid->entry.context, context);
89 if (rc)
90 return rc;
91
92#if CONFIG_SECURITY_SELINUX_SID2STR_CACHE_SIZE > 0
93 isid->entry.cache = NULL;
94#endif
95 isid->set = 1;
96
97 hash = context_compute_hash(context);
98
99 /*
100 * Multiple initial sids may map to the same context. Check that this
101 * context is not already represented in the context_to_sid hashtable
102 * to avoid duplicate entries and long linked lists upon hash
103 * collision.
104 */
105 if (!context_to_sid(s, context, hash)) {
106 isid->entry.sid = sid;
107 isid->entry.hash = hash;
108 hash_add(s->context_to_sid, &isid->entry.list, hash);
109 }
110
111 return 0;
112}
113
114int sidtab_hash_stats(struct sidtab *sidtab, char *page)
115{
116 int i;
117 int chain_len = 0;
118 int slots_used = 0;
119 int entries = 0;
120 int max_chain_len = 0;
121 int cur_bucket = 0;
122 struct sidtab_entry *entry;
123
124 rcu_read_lock();
125 hash_for_each_rcu(sidtab->context_to_sid, i, entry, list) {
126 entries++;
127 if (i == cur_bucket) {
128 chain_len++;
129 if (chain_len == 1)
130 slots_used++;
131 } else {
132 cur_bucket = i;
133 if (chain_len > max_chain_len)
134 max_chain_len = chain_len;
135 chain_len = 0;
136 }
137 }
138 rcu_read_unlock();
139
140 if (chain_len > max_chain_len)
141 max_chain_len = chain_len;
142
143 return scnprintf(page, PAGE_SIZE, "entries: %d\nbuckets used: %d/%d\n"
144 "longest chain: %d\n", entries,
145 slots_used, SIDTAB_HASH_BUCKETS, max_chain_len);
146}
147
148static u32 sidtab_level_from_count(u32 count)
149{
150 u32 capacity = SIDTAB_LEAF_ENTRIES;
151 u32 level = 0;
152
153 while (count > capacity) {
154 capacity <<= SIDTAB_INNER_SHIFT;
155 ++level;
156 }
157 return level;
158}
159
160static int sidtab_alloc_roots(struct sidtab *s, u32 level)
161{
162 u32 l;
163
164 if (!s->roots[0].ptr_leaf) {
165 s->roots[0].ptr_leaf = kzalloc(SIDTAB_NODE_ALLOC_SIZE,
166 GFP_ATOMIC);
167 if (!s->roots[0].ptr_leaf)
168 return -ENOMEM;
169 }
170 for (l = 1; l <= level; ++l)
171 if (!s->roots[l].ptr_inner) {
172 s->roots[l].ptr_inner = kzalloc(SIDTAB_NODE_ALLOC_SIZE,
173 GFP_ATOMIC);
174 if (!s->roots[l].ptr_inner)
175 return -ENOMEM;
176 s->roots[l].ptr_inner->entries[0] = s->roots[l - 1];
177 }
178 return 0;
179}
180
181static struct sidtab_entry *sidtab_do_lookup(struct sidtab *s, u32 index,
182 int alloc)
183{
184 union sidtab_entry_inner *entry;
185 u32 level, capacity_shift, leaf_index = index / SIDTAB_LEAF_ENTRIES;
186
187 /* find the level of the subtree we need */
188 level = sidtab_level_from_count(index + 1);
189 capacity_shift = level * SIDTAB_INNER_SHIFT;
190
191 /* allocate roots if needed */
192 if (alloc && sidtab_alloc_roots(s, level) != 0)
193 return NULL;
194
195 /* lookup inside the subtree */
196 entry = &s->roots[level];
197 while (level != 0) {
198 capacity_shift -= SIDTAB_INNER_SHIFT;
199 --level;
200
201 entry = &entry->ptr_inner->entries[leaf_index >> capacity_shift];
202 leaf_index &= ((u32)1 << capacity_shift) - 1;
203
204 if (!entry->ptr_inner) {
205 if (alloc)
206 entry->ptr_inner = kzalloc(SIDTAB_NODE_ALLOC_SIZE,
207 GFP_ATOMIC);
208 if (!entry->ptr_inner)
209 return NULL;
210 }
211 }
212 if (!entry->ptr_leaf) {
213 if (alloc)
214 entry->ptr_leaf = kzalloc(SIDTAB_NODE_ALLOC_SIZE,
215 GFP_ATOMIC);
216 if (!entry->ptr_leaf)
217 return NULL;
218 }
219 return &entry->ptr_leaf->entries[index % SIDTAB_LEAF_ENTRIES];
220}
221
222static struct sidtab_entry *sidtab_lookup(struct sidtab *s, u32 index)
223{
224 /* read entries only after reading count */
225 u32 count = smp_load_acquire(&s->count);
226
227 if (index >= count)
228 return NULL;
229
230 return sidtab_do_lookup(s, index, 0);
231}
232
233static struct sidtab_entry *sidtab_lookup_initial(struct sidtab *s, u32 sid)
234{
235 return s->isids[sid - 1].set ? &s->isids[sid - 1].entry : NULL;
236}
237
238static struct sidtab_entry *sidtab_search_core(struct sidtab *s, u32 sid,
239 int force)
240{
241 if (sid != 0) {
242 struct sidtab_entry *entry;
243
244 if (sid > SECINITSID_NUM)
245 entry = sidtab_lookup(s, sid_to_index(sid));
246 else
247 entry = sidtab_lookup_initial(s, sid);
248 if (entry && (!entry->context.len || force))
249 return entry;
250 }
251
252 return sidtab_lookup_initial(s, SECINITSID_UNLABELED);
253}
254
255struct sidtab_entry *sidtab_search_entry(struct sidtab *s, u32 sid)
256{
257 return sidtab_search_core(s, sid, 0);
258}
259
260struct sidtab_entry *sidtab_search_entry_force(struct sidtab *s, u32 sid)
261{
262 return sidtab_search_core(s, sid, 1);
263}
264
265int sidtab_context_to_sid(struct sidtab *s, struct context *context,
266 u32 *sid)
267{
268 unsigned long flags;
269 u32 count, hash = context_compute_hash(context);
270 struct sidtab_convert_params *convert;
271 struct sidtab_entry *dst, *dst_convert;
272 int rc;
273
274 *sid = context_to_sid(s, context, hash);
275 if (*sid)
276 return 0;
277
278 /* lock-free search failed: lock, re-search, and insert if not found */
279 spin_lock_irqsave(&s->lock, flags);
280
281 rc = 0;
282 *sid = context_to_sid(s, context, hash);
283 if (*sid)
284 goto out_unlock;
285
286 if (unlikely(s->frozen)) {
287 /*
288 * This sidtab is now frozen - tell the caller to abort and
289 * get the new one.
290 */
291 rc = -ESTALE;
292 goto out_unlock;
293 }
294
295 count = s->count;
296
297 /* bail out if we already reached max entries */
298 rc = -EOVERFLOW;
299 if (count >= SIDTAB_MAX)
300 goto out_unlock;
301
302 /* insert context into new entry */
303 rc = -ENOMEM;
304 dst = sidtab_do_lookup(s, count, 1);
305 if (!dst)
306 goto out_unlock;
307
308 dst->sid = index_to_sid(count);
309 dst->hash = hash;
310
311 rc = context_cpy(&dst->context, context);
312 if (rc)
313 goto out_unlock;
314
315 /*
316 * if we are building a new sidtab, we need to convert the context
317 * and insert it there as well
318 */
319 convert = s->convert;
320 if (convert) {
321 struct sidtab *target = convert->target;
322
323 rc = -ENOMEM;
324 dst_convert = sidtab_do_lookup(target, count, 1);
325 if (!dst_convert) {
326 context_destroy(&dst->context);
327 goto out_unlock;
328 }
329
330 rc = services_convert_context(convert->args,
331 context, &dst_convert->context,
332 GFP_ATOMIC);
333 if (rc) {
334 context_destroy(&dst->context);
335 goto out_unlock;
336 }
337 dst_convert->sid = index_to_sid(count);
338 dst_convert->hash = context_compute_hash(&dst_convert->context);
339 target->count = count + 1;
340
341 hash_add_rcu(target->context_to_sid,
342 &dst_convert->list, dst_convert->hash);
343 }
344
345 if (context->len)
346 pr_info("SELinux: Context %s is not valid (left unmapped).\n",
347 context->str);
348
349 *sid = index_to_sid(count);
350
351 /* write entries before updating count */
352 smp_store_release(&s->count, count + 1);
353 hash_add_rcu(s->context_to_sid, &dst->list, dst->hash);
354
355 rc = 0;
356out_unlock:
357 spin_unlock_irqrestore(&s->lock, flags);
358 return rc;
359}
360
361static void sidtab_convert_hashtable(struct sidtab *s, u32 count)
362{
363 struct sidtab_entry *entry;
364 u32 i;
365
366 for (i = 0; i < count; i++) {
367 entry = sidtab_do_lookup(s, i, 0);
368 entry->sid = index_to_sid(i);
369 entry->hash = context_compute_hash(&entry->context);
370
371 hash_add_rcu(s->context_to_sid, &entry->list, entry->hash);
372 }
373}
374
375static int sidtab_convert_tree(union sidtab_entry_inner *edst,
376 union sidtab_entry_inner *esrc,
377 u32 *pos, u32 count, u32 level,
378 struct sidtab_convert_params *convert)
379{
380 int rc;
381 u32 i;
382
383 if (level != 0) {
384 if (!edst->ptr_inner) {
385 edst->ptr_inner = kzalloc(SIDTAB_NODE_ALLOC_SIZE,
386 GFP_KERNEL);
387 if (!edst->ptr_inner)
388 return -ENOMEM;
389 }
390 i = 0;
391 while (i < SIDTAB_INNER_ENTRIES && *pos < count) {
392 rc = sidtab_convert_tree(&edst->ptr_inner->entries[i],
393 &esrc->ptr_inner->entries[i],
394 pos, count, level - 1,
395 convert);
396 if (rc)
397 return rc;
398 i++;
399 }
400 } else {
401 if (!edst->ptr_leaf) {
402 edst->ptr_leaf = kzalloc(SIDTAB_NODE_ALLOC_SIZE,
403 GFP_KERNEL);
404 if (!edst->ptr_leaf)
405 return -ENOMEM;
406 }
407 i = 0;
408 while (i < SIDTAB_LEAF_ENTRIES && *pos < count) {
409 rc = services_convert_context(convert->args,
410 &esrc->ptr_leaf->entries[i].context,
411 &edst->ptr_leaf->entries[i].context,
412 GFP_KERNEL);
413 if (rc)
414 return rc;
415 (*pos)++;
416 i++;
417 }
418 cond_resched();
419 }
420 return 0;
421}
422
423int sidtab_convert(struct sidtab *s, struct sidtab_convert_params *params)
424{
425 unsigned long flags;
426 u32 count, level, pos;
427 int rc;
428
429 spin_lock_irqsave(&s->lock, flags);
430
431 /* concurrent policy loads are not allowed */
432 if (s->convert) {
433 spin_unlock_irqrestore(&s->lock, flags);
434 return -EBUSY;
435 }
436
437 count = s->count;
438 level = sidtab_level_from_count(count);
439
440 /* allocate last leaf in the new sidtab (to avoid race with
441 * live convert)
442 */
443 rc = sidtab_do_lookup(params->target, count - 1, 1) ? 0 : -ENOMEM;
444 if (rc) {
445 spin_unlock_irqrestore(&s->lock, flags);
446 return rc;
447 }
448
449 /* set count in case no new entries are added during conversion */
450 params->target->count = count;
451
452 /* enable live convert of new entries */
453 s->convert = params;
454
455 /* we can safely convert the tree outside the lock */
456 spin_unlock_irqrestore(&s->lock, flags);
457
458 pr_info("SELinux: Converting %u SID table entries...\n", count);
459
460 /* convert all entries not covered by live convert */
461 pos = 0;
462 rc = sidtab_convert_tree(¶ms->target->roots[level],
463 &s->roots[level], &pos, count, level, params);
464 if (rc) {
465 /* we need to keep the old table - disable live convert */
466 spin_lock_irqsave(&s->lock, flags);
467 s->convert = NULL;
468 spin_unlock_irqrestore(&s->lock, flags);
469 return rc;
470 }
471 /*
472 * The hashtable can also be modified in sidtab_context_to_sid()
473 * so we must re-acquire the lock here.
474 */
475 spin_lock_irqsave(&s->lock, flags);
476 sidtab_convert_hashtable(params->target, count);
477 spin_unlock_irqrestore(&s->lock, flags);
478
479 return 0;
480}
481
482void sidtab_cancel_convert(struct sidtab *s)
483{
484 unsigned long flags;
485
486 /* cancelling policy load - disable live convert of sidtab */
487 spin_lock_irqsave(&s->lock, flags);
488 s->convert = NULL;
489 spin_unlock_irqrestore(&s->lock, flags);
490}
491
492void sidtab_freeze_begin(struct sidtab *s, unsigned long *flags) __acquires(&s->lock)
493{
494 spin_lock_irqsave(&s->lock, *flags);
495 s->frozen = true;
496 s->convert = NULL;
497}
498void sidtab_freeze_end(struct sidtab *s, unsigned long *flags) __releases(&s->lock)
499{
500 spin_unlock_irqrestore(&s->lock, *flags);
501}
502
503static void sidtab_destroy_entry(struct sidtab_entry *entry)
504{
505 context_destroy(&entry->context);
506#if CONFIG_SECURITY_SELINUX_SID2STR_CACHE_SIZE > 0
507 kfree(rcu_dereference_raw(entry->cache));
508#endif
509}
510
511static void sidtab_destroy_tree(union sidtab_entry_inner entry, u32 level)
512{
513 u32 i;
514
515 if (level != 0) {
516 struct sidtab_node_inner *node = entry.ptr_inner;
517
518 if (!node)
519 return;
520
521 for (i = 0; i < SIDTAB_INNER_ENTRIES; i++)
522 sidtab_destroy_tree(node->entries[i], level - 1);
523 kfree(node);
524 } else {
525 struct sidtab_node_leaf *node = entry.ptr_leaf;
526
527 if (!node)
528 return;
529
530 for (i = 0; i < SIDTAB_LEAF_ENTRIES; i++)
531 sidtab_destroy_entry(&node->entries[i]);
532 kfree(node);
533 }
534}
535
536void sidtab_destroy(struct sidtab *s)
537{
538 u32 i, level;
539
540 for (i = 0; i < SECINITSID_NUM; i++)
541 if (s->isids[i].set)
542 sidtab_destroy_entry(&s->isids[i].entry);
543
544 level = SIDTAB_MAX_LEVEL;
545 while (level && !s->roots[level].ptr_inner)
546 --level;
547
548 sidtab_destroy_tree(s->roots[level], level);
549 /*
550 * The context_to_sid hashtable's objects are all shared
551 * with the isids array and context tree, and so don't need
552 * to be cleaned up here.
553 */
554}
555
556#if CONFIG_SECURITY_SELINUX_SID2STR_CACHE_SIZE > 0
557
558void sidtab_sid2str_put(struct sidtab *s, struct sidtab_entry *entry,
559 const char *str, u32 str_len)
560{
561 struct sidtab_str_cache *cache, *victim = NULL;
562 unsigned long flags;
563
564 /* do not cache invalid contexts */
565 if (entry->context.len)
566 return;
567
568 spin_lock_irqsave(&s->cache_lock, flags);
569
570 cache = rcu_dereference_protected(entry->cache,
571 lockdep_is_held(&s->cache_lock));
572 if (cache) {
573 /* entry in cache - just bump to the head of LRU list */
574 list_move(&cache->lru_member, &s->cache_lru_list);
575 goto out_unlock;
576 }
577
578 cache = kmalloc(struct_size(cache, str, str_len), GFP_ATOMIC);
579 if (!cache)
580 goto out_unlock;
581
582 if (s->cache_free_slots == 0) {
583 /* pop a cache entry from the tail and free it */
584 victim = container_of(s->cache_lru_list.prev,
585 struct sidtab_str_cache, lru_member);
586 list_del(&victim->lru_member);
587 rcu_assign_pointer(victim->parent->cache, NULL);
588 } else {
589 s->cache_free_slots--;
590 }
591 cache->parent = entry;
592 cache->len = str_len;
593 memcpy(cache->str, str, str_len);
594 list_add(&cache->lru_member, &s->cache_lru_list);
595
596 rcu_assign_pointer(entry->cache, cache);
597
598out_unlock:
599 spin_unlock_irqrestore(&s->cache_lock, flags);
600 kfree_rcu(victim, rcu_member);
601}
602
603int sidtab_sid2str_get(struct sidtab *s, struct sidtab_entry *entry,
604 char **out, u32 *out_len)
605{
606 struct sidtab_str_cache *cache;
607 int rc = 0;
608
609 if (entry->context.len)
610 return -ENOENT; /* do not cache invalid contexts */
611
612 rcu_read_lock();
613
614 cache = rcu_dereference(entry->cache);
615 if (!cache) {
616 rc = -ENOENT;
617 } else {
618 *out_len = cache->len;
619 if (out) {
620 *out = kmemdup(cache->str, cache->len, GFP_ATOMIC);
621 if (!*out)
622 rc = -ENOMEM;
623 }
624 }
625
626 rcu_read_unlock();
627
628 if (!rc && out)
629 sidtab_sid2str_put(s, entry, *out, *out_len);
630 return rc;
631}
632
633#endif /* CONFIG_SECURITY_SELINUX_SID2STR_CACHE_SIZE > 0 */
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Implementation of the SID table type.
4 *
5 * Original author: Stephen Smalley, <sds@tycho.nsa.gov>
6 * Author: Ondrej Mosnacek, <omosnacek@gmail.com>
7 *
8 * Copyright (C) 2018 Red Hat, Inc.
9 */
10#include <linux/errno.h>
11#include <linux/kernel.h>
12#include <linux/list.h>
13#include <linux/rcupdate.h>
14#include <linux/slab.h>
15#include <linux/sched.h>
16#include <linux/spinlock.h>
17#include <asm/barrier.h>
18#include "flask.h"
19#include "security.h"
20#include "sidtab.h"
21
22struct sidtab_str_cache {
23 struct rcu_head rcu_member;
24 struct list_head lru_member;
25 struct sidtab_entry *parent;
26 u32 len;
27 char str[];
28};
29
30#define index_to_sid(index) (index + SECINITSID_NUM + 1)
31#define sid_to_index(sid) (sid - (SECINITSID_NUM + 1))
32
33int sidtab_init(struct sidtab *s)
34{
35 u32 i;
36
37 memset(s->roots, 0, sizeof(s->roots));
38
39 for (i = 0; i < SECINITSID_NUM; i++)
40 s->isids[i].set = 0;
41
42 s->count = 0;
43 s->convert = NULL;
44 hash_init(s->context_to_sid);
45
46 spin_lock_init(&s->lock);
47
48#if CONFIG_SECURITY_SELINUX_SID2STR_CACHE_SIZE > 0
49 s->cache_free_slots = CONFIG_SECURITY_SELINUX_SID2STR_CACHE_SIZE;
50 INIT_LIST_HEAD(&s->cache_lru_list);
51 spin_lock_init(&s->cache_lock);
52#endif
53
54 return 0;
55}
56
57static u32 context_to_sid(struct sidtab *s, struct context *context, u32 hash)
58{
59 struct sidtab_entry *entry;
60 u32 sid = 0;
61
62 rcu_read_lock();
63 hash_for_each_possible_rcu(s->context_to_sid, entry, list, hash) {
64 if (entry->hash != hash)
65 continue;
66 if (context_cmp(&entry->context, context)) {
67 sid = entry->sid;
68 break;
69 }
70 }
71 rcu_read_unlock();
72 return sid;
73}
74
75int sidtab_set_initial(struct sidtab *s, u32 sid, struct context *context)
76{
77 struct sidtab_isid_entry *isid;
78 u32 hash;
79 int rc;
80
81 if (sid == 0 || sid > SECINITSID_NUM)
82 return -EINVAL;
83
84 isid = &s->isids[sid - 1];
85
86 rc = context_cpy(&isid->entry.context, context);
87 if (rc)
88 return rc;
89
90#if CONFIG_SECURITY_SELINUX_SID2STR_CACHE_SIZE > 0
91 isid->entry.cache = NULL;
92#endif
93 isid->set = 1;
94
95 hash = context_compute_hash(context);
96
97 /*
98 * Multiple initial sids may map to the same context. Check that this
99 * context is not already represented in the context_to_sid hashtable
100 * to avoid duplicate entries and long linked lists upon hash
101 * collision.
102 */
103 if (!context_to_sid(s, context, hash)) {
104 isid->entry.sid = sid;
105 isid->entry.hash = hash;
106 hash_add(s->context_to_sid, &isid->entry.list, hash);
107 }
108
109 return 0;
110}
111
112int sidtab_hash_stats(struct sidtab *sidtab, char *page)
113{
114 int i;
115 int chain_len = 0;
116 int slots_used = 0;
117 int entries = 0;
118 int max_chain_len = 0;
119 int cur_bucket = 0;
120 struct sidtab_entry *entry;
121
122 rcu_read_lock();
123 hash_for_each_rcu(sidtab->context_to_sid, i, entry, list) {
124 entries++;
125 if (i == cur_bucket) {
126 chain_len++;
127 if (chain_len == 1)
128 slots_used++;
129 } else {
130 cur_bucket = i;
131 if (chain_len > max_chain_len)
132 max_chain_len = chain_len;
133 chain_len = 0;
134 }
135 }
136 rcu_read_unlock();
137
138 if (chain_len > max_chain_len)
139 max_chain_len = chain_len;
140
141 return scnprintf(page, PAGE_SIZE, "entries: %d\nbuckets used: %d/%d\n"
142 "longest chain: %d\n", entries,
143 slots_used, SIDTAB_HASH_BUCKETS, max_chain_len);
144}
145
146static u32 sidtab_level_from_count(u32 count)
147{
148 u32 capacity = SIDTAB_LEAF_ENTRIES;
149 u32 level = 0;
150
151 while (count > capacity) {
152 capacity <<= SIDTAB_INNER_SHIFT;
153 ++level;
154 }
155 return level;
156}
157
158static int sidtab_alloc_roots(struct sidtab *s, u32 level)
159{
160 u32 l;
161
162 if (!s->roots[0].ptr_leaf) {
163 s->roots[0].ptr_leaf = kzalloc(SIDTAB_NODE_ALLOC_SIZE,
164 GFP_ATOMIC);
165 if (!s->roots[0].ptr_leaf)
166 return -ENOMEM;
167 }
168 for (l = 1; l <= level; ++l)
169 if (!s->roots[l].ptr_inner) {
170 s->roots[l].ptr_inner = kzalloc(SIDTAB_NODE_ALLOC_SIZE,
171 GFP_ATOMIC);
172 if (!s->roots[l].ptr_inner)
173 return -ENOMEM;
174 s->roots[l].ptr_inner->entries[0] = s->roots[l - 1];
175 }
176 return 0;
177}
178
179static struct sidtab_entry *sidtab_do_lookup(struct sidtab *s, u32 index,
180 int alloc)
181{
182 union sidtab_entry_inner *entry;
183 u32 level, capacity_shift, leaf_index = index / SIDTAB_LEAF_ENTRIES;
184
185 /* find the level of the subtree we need */
186 level = sidtab_level_from_count(index + 1);
187 capacity_shift = level * SIDTAB_INNER_SHIFT;
188
189 /* allocate roots if needed */
190 if (alloc && sidtab_alloc_roots(s, level) != 0)
191 return NULL;
192
193 /* lookup inside the subtree */
194 entry = &s->roots[level];
195 while (level != 0) {
196 capacity_shift -= SIDTAB_INNER_SHIFT;
197 --level;
198
199 entry = &entry->ptr_inner->entries[leaf_index >> capacity_shift];
200 leaf_index &= ((u32)1 << capacity_shift) - 1;
201
202 if (!entry->ptr_inner) {
203 if (alloc)
204 entry->ptr_inner = kzalloc(SIDTAB_NODE_ALLOC_SIZE,
205 GFP_ATOMIC);
206 if (!entry->ptr_inner)
207 return NULL;
208 }
209 }
210 if (!entry->ptr_leaf) {
211 if (alloc)
212 entry->ptr_leaf = kzalloc(SIDTAB_NODE_ALLOC_SIZE,
213 GFP_ATOMIC);
214 if (!entry->ptr_leaf)
215 return NULL;
216 }
217 return &entry->ptr_leaf->entries[index % SIDTAB_LEAF_ENTRIES];
218}
219
220static struct sidtab_entry *sidtab_lookup(struct sidtab *s, u32 index)
221{
222 /* read entries only after reading count */
223 u32 count = smp_load_acquire(&s->count);
224
225 if (index >= count)
226 return NULL;
227
228 return sidtab_do_lookup(s, index, 0);
229}
230
231static struct sidtab_entry *sidtab_lookup_initial(struct sidtab *s, u32 sid)
232{
233 return s->isids[sid - 1].set ? &s->isids[sid - 1].entry : NULL;
234}
235
236static struct sidtab_entry *sidtab_search_core(struct sidtab *s, u32 sid,
237 int force)
238{
239 if (sid != 0) {
240 struct sidtab_entry *entry;
241
242 if (sid > SECINITSID_NUM)
243 entry = sidtab_lookup(s, sid_to_index(sid));
244 else
245 entry = sidtab_lookup_initial(s, sid);
246 if (entry && (!entry->context.len || force))
247 return entry;
248 }
249
250 return sidtab_lookup_initial(s, SECINITSID_UNLABELED);
251}
252
253struct sidtab_entry *sidtab_search_entry(struct sidtab *s, u32 sid)
254{
255 return sidtab_search_core(s, sid, 0);
256}
257
258struct sidtab_entry *sidtab_search_entry_force(struct sidtab *s, u32 sid)
259{
260 return sidtab_search_core(s, sid, 1);
261}
262
263int sidtab_context_to_sid(struct sidtab *s, struct context *context,
264 u32 *sid)
265{
266 unsigned long flags;
267 u32 count, hash = context_compute_hash(context);
268 struct sidtab_convert_params *convert;
269 struct sidtab_entry *dst, *dst_convert;
270 int rc;
271
272 *sid = context_to_sid(s, context, hash);
273 if (*sid)
274 return 0;
275
276 /* lock-free search failed: lock, re-search, and insert if not found */
277 spin_lock_irqsave(&s->lock, flags);
278
279 rc = 0;
280 *sid = context_to_sid(s, context, hash);
281 if (*sid)
282 goto out_unlock;
283
284 count = s->count;
285 convert = s->convert;
286
287 /* bail out if we already reached max entries */
288 rc = -EOVERFLOW;
289 if (count >= SIDTAB_MAX)
290 goto out_unlock;
291
292 /* insert context into new entry */
293 rc = -ENOMEM;
294 dst = sidtab_do_lookup(s, count, 1);
295 if (!dst)
296 goto out_unlock;
297
298 dst->sid = index_to_sid(count);
299 dst->hash = hash;
300
301 rc = context_cpy(&dst->context, context);
302 if (rc)
303 goto out_unlock;
304
305 /*
306 * if we are building a new sidtab, we need to convert the context
307 * and insert it there as well
308 */
309 if (convert) {
310 rc = -ENOMEM;
311 dst_convert = sidtab_do_lookup(convert->target, count, 1);
312 if (!dst_convert) {
313 context_destroy(&dst->context);
314 goto out_unlock;
315 }
316
317 rc = convert->func(context, &dst_convert->context,
318 convert->args);
319 if (rc) {
320 context_destroy(&dst->context);
321 goto out_unlock;
322 }
323 dst_convert->sid = index_to_sid(count);
324 dst_convert->hash = context_compute_hash(&dst_convert->context);
325 convert->target->count = count + 1;
326
327 hash_add_rcu(convert->target->context_to_sid,
328 &dst_convert->list, dst_convert->hash);
329 }
330
331 if (context->len)
332 pr_info("SELinux: Context %s is not valid (left unmapped).\n",
333 context->str);
334
335 *sid = index_to_sid(count);
336
337 /* write entries before updating count */
338 smp_store_release(&s->count, count + 1);
339 hash_add_rcu(s->context_to_sid, &dst->list, dst->hash);
340
341 rc = 0;
342out_unlock:
343 spin_unlock_irqrestore(&s->lock, flags);
344 return rc;
345}
346
347static void sidtab_convert_hashtable(struct sidtab *s, u32 count)
348{
349 struct sidtab_entry *entry;
350 u32 i;
351
352 for (i = 0; i < count; i++) {
353 entry = sidtab_do_lookup(s, i, 0);
354 entry->sid = index_to_sid(i);
355 entry->hash = context_compute_hash(&entry->context);
356
357 hash_add_rcu(s->context_to_sid, &entry->list, entry->hash);
358 }
359}
360
361static int sidtab_convert_tree(union sidtab_entry_inner *edst,
362 union sidtab_entry_inner *esrc,
363 u32 *pos, u32 count, u32 level,
364 struct sidtab_convert_params *convert)
365{
366 int rc;
367 u32 i;
368
369 if (level != 0) {
370 if (!edst->ptr_inner) {
371 edst->ptr_inner = kzalloc(SIDTAB_NODE_ALLOC_SIZE,
372 GFP_KERNEL);
373 if (!edst->ptr_inner)
374 return -ENOMEM;
375 }
376 i = 0;
377 while (i < SIDTAB_INNER_ENTRIES && *pos < count) {
378 rc = sidtab_convert_tree(&edst->ptr_inner->entries[i],
379 &esrc->ptr_inner->entries[i],
380 pos, count, level - 1,
381 convert);
382 if (rc)
383 return rc;
384 i++;
385 }
386 } else {
387 if (!edst->ptr_leaf) {
388 edst->ptr_leaf = kzalloc(SIDTAB_NODE_ALLOC_SIZE,
389 GFP_KERNEL);
390 if (!edst->ptr_leaf)
391 return -ENOMEM;
392 }
393 i = 0;
394 while (i < SIDTAB_LEAF_ENTRIES && *pos < count) {
395 rc = convert->func(&esrc->ptr_leaf->entries[i].context,
396 &edst->ptr_leaf->entries[i].context,
397 convert->args);
398 if (rc)
399 return rc;
400 (*pos)++;
401 i++;
402 }
403 cond_resched();
404 }
405 return 0;
406}
407
408int sidtab_convert(struct sidtab *s, struct sidtab_convert_params *params)
409{
410 unsigned long flags;
411 u32 count, level, pos;
412 int rc;
413
414 spin_lock_irqsave(&s->lock, flags);
415
416 /* concurrent policy loads are not allowed */
417 if (s->convert) {
418 spin_unlock_irqrestore(&s->lock, flags);
419 return -EBUSY;
420 }
421
422 count = s->count;
423 level = sidtab_level_from_count(count);
424
425 /* allocate last leaf in the new sidtab (to avoid race with
426 * live convert)
427 */
428 rc = sidtab_do_lookup(params->target, count - 1, 1) ? 0 : -ENOMEM;
429 if (rc) {
430 spin_unlock_irqrestore(&s->lock, flags);
431 return rc;
432 }
433
434 /* set count in case no new entries are added during conversion */
435 params->target->count = count;
436
437 /* enable live convert of new entries */
438 s->convert = params;
439
440 /* we can safely convert the tree outside the lock */
441 spin_unlock_irqrestore(&s->lock, flags);
442
443 pr_info("SELinux: Converting %u SID table entries...\n", count);
444
445 /* convert all entries not covered by live convert */
446 pos = 0;
447 rc = sidtab_convert_tree(¶ms->target->roots[level],
448 &s->roots[level], &pos, count, level, params);
449 if (rc) {
450 /* we need to keep the old table - disable live convert */
451 spin_lock_irqsave(&s->lock, flags);
452 s->convert = NULL;
453 spin_unlock_irqrestore(&s->lock, flags);
454 return rc;
455 }
456 /*
457 * The hashtable can also be modified in sidtab_context_to_sid()
458 * so we must re-acquire the lock here.
459 */
460 spin_lock_irqsave(&s->lock, flags);
461 sidtab_convert_hashtable(params->target, count);
462 spin_unlock_irqrestore(&s->lock, flags);
463
464 return 0;
465}
466
467static void sidtab_destroy_entry(struct sidtab_entry *entry)
468{
469 context_destroy(&entry->context);
470#if CONFIG_SECURITY_SELINUX_SID2STR_CACHE_SIZE > 0
471 kfree(rcu_dereference_raw(entry->cache));
472#endif
473}
474
475static void sidtab_destroy_tree(union sidtab_entry_inner entry, u32 level)
476{
477 u32 i;
478
479 if (level != 0) {
480 struct sidtab_node_inner *node = entry.ptr_inner;
481
482 if (!node)
483 return;
484
485 for (i = 0; i < SIDTAB_INNER_ENTRIES; i++)
486 sidtab_destroy_tree(node->entries[i], level - 1);
487 kfree(node);
488 } else {
489 struct sidtab_node_leaf *node = entry.ptr_leaf;
490
491 if (!node)
492 return;
493
494 for (i = 0; i < SIDTAB_LEAF_ENTRIES; i++)
495 sidtab_destroy_entry(&node->entries[i]);
496 kfree(node);
497 }
498}
499
500void sidtab_destroy(struct sidtab *s)
501{
502 u32 i, level;
503
504 for (i = 0; i < SECINITSID_NUM; i++)
505 if (s->isids[i].set)
506 sidtab_destroy_entry(&s->isids[i].entry);
507
508 level = SIDTAB_MAX_LEVEL;
509 while (level && !s->roots[level].ptr_inner)
510 --level;
511
512 sidtab_destroy_tree(s->roots[level], level);
513 /*
514 * The context_to_sid hashtable's objects are all shared
515 * with the isids array and context tree, and so don't need
516 * to be cleaned up here.
517 */
518}
519
520#if CONFIG_SECURITY_SELINUX_SID2STR_CACHE_SIZE > 0
521
522void sidtab_sid2str_put(struct sidtab *s, struct sidtab_entry *entry,
523 const char *str, u32 str_len)
524{
525 struct sidtab_str_cache *cache, *victim = NULL;
526 unsigned long flags;
527
528 /* do not cache invalid contexts */
529 if (entry->context.len)
530 return;
531
532 spin_lock_irqsave(&s->cache_lock, flags);
533
534 cache = rcu_dereference_protected(entry->cache,
535 lockdep_is_held(&s->cache_lock));
536 if (cache) {
537 /* entry in cache - just bump to the head of LRU list */
538 list_move(&cache->lru_member, &s->cache_lru_list);
539 goto out_unlock;
540 }
541
542 cache = kmalloc(sizeof(struct sidtab_str_cache) + str_len, GFP_ATOMIC);
543 if (!cache)
544 goto out_unlock;
545
546 if (s->cache_free_slots == 0) {
547 /* pop a cache entry from the tail and free it */
548 victim = container_of(s->cache_lru_list.prev,
549 struct sidtab_str_cache, lru_member);
550 list_del(&victim->lru_member);
551 rcu_assign_pointer(victim->parent->cache, NULL);
552 } else {
553 s->cache_free_slots--;
554 }
555 cache->parent = entry;
556 cache->len = str_len;
557 memcpy(cache->str, str, str_len);
558 list_add(&cache->lru_member, &s->cache_lru_list);
559
560 rcu_assign_pointer(entry->cache, cache);
561
562out_unlock:
563 spin_unlock_irqrestore(&s->cache_lock, flags);
564 kfree_rcu(victim, rcu_member);
565}
566
567int sidtab_sid2str_get(struct sidtab *s, struct sidtab_entry *entry,
568 char **out, u32 *out_len)
569{
570 struct sidtab_str_cache *cache;
571 int rc = 0;
572
573 if (entry->context.len)
574 return -ENOENT; /* do not cache invalid contexts */
575
576 rcu_read_lock();
577
578 cache = rcu_dereference(entry->cache);
579 if (!cache) {
580 rc = -ENOENT;
581 } else {
582 *out_len = cache->len;
583 if (out) {
584 *out = kmemdup(cache->str, cache->len, GFP_ATOMIC);
585 if (!*out)
586 rc = -ENOMEM;
587 }
588 }
589
590 rcu_read_unlock();
591
592 if (!rc && out)
593 sidtab_sid2str_put(s, entry, *out, *out_len);
594 return rc;
595}
596
597#endif /* CONFIG_SECURITY_SELINUX_SID2STR_CACHE_SIZE > 0 */