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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Implementation of the SID table type.
4 *
5 * Author : Stephen Smalley, <sds@tycho.nsa.gov>
6 */
7#include <linux/kernel.h>
8#include <linux/slab.h>
9#include <linux/spinlock.h>
10#include <linux/errno.h>
11#include "flask.h"
12#include "security.h"
13#include "sidtab.h"
14
15#define SIDTAB_HASH(sid) \
16(sid & SIDTAB_HASH_MASK)
17
18int sidtab_init(struct sidtab *s)
19{
20 int i;
21
22 s->htable = kmalloc_array(SIDTAB_SIZE, sizeof(*s->htable), GFP_ATOMIC);
23 if (!s->htable)
24 return -ENOMEM;
25 for (i = 0; i < SIDTAB_SIZE; i++)
26 s->htable[i] = NULL;
27 s->nel = 0;
28 s->next_sid = 1;
29 s->shutdown = 0;
30 spin_lock_init(&s->lock);
31 return 0;
32}
33
34int sidtab_insert(struct sidtab *s, u32 sid, struct context *context)
35{
36 int hvalue;
37 struct sidtab_node *prev, *cur, *newnode;
38
39 if (!s)
40 return -ENOMEM;
41
42 hvalue = SIDTAB_HASH(sid);
43 prev = NULL;
44 cur = s->htable[hvalue];
45 while (cur && sid > cur->sid) {
46 prev = cur;
47 cur = cur->next;
48 }
49
50 if (cur && sid == cur->sid)
51 return -EEXIST;
52
53 newnode = kmalloc(sizeof(*newnode), GFP_ATOMIC);
54 if (!newnode)
55 return -ENOMEM;
56
57 newnode->sid = sid;
58 if (context_cpy(&newnode->context, context)) {
59 kfree(newnode);
60 return -ENOMEM;
61 }
62
63 if (prev) {
64 newnode->next = prev->next;
65 wmb();
66 prev->next = newnode;
67 } else {
68 newnode->next = s->htable[hvalue];
69 wmb();
70 s->htable[hvalue] = newnode;
71 }
72
73 s->nel++;
74 if (sid >= s->next_sid)
75 s->next_sid = sid + 1;
76 return 0;
77}
78
79static struct context *sidtab_search_core(struct sidtab *s, u32 sid, int force)
80{
81 int hvalue;
82 struct sidtab_node *cur;
83
84 if (!s)
85 return NULL;
86
87 hvalue = SIDTAB_HASH(sid);
88 cur = s->htable[hvalue];
89 while (cur && sid > cur->sid)
90 cur = cur->next;
91
92 if (force && cur && sid == cur->sid && cur->context.len)
93 return &cur->context;
94
95 if (!cur || sid != cur->sid || cur->context.len) {
96 /* Remap invalid SIDs to the unlabeled SID. */
97 sid = SECINITSID_UNLABELED;
98 hvalue = SIDTAB_HASH(sid);
99 cur = s->htable[hvalue];
100 while (cur && sid > cur->sid)
101 cur = cur->next;
102 if (!cur || sid != cur->sid)
103 return NULL;
104 }
105
106 return &cur->context;
107}
108
109struct context *sidtab_search(struct sidtab *s, u32 sid)
110{
111 return sidtab_search_core(s, sid, 0);
112}
113
114struct context *sidtab_search_force(struct sidtab *s, u32 sid)
115{
116 return sidtab_search_core(s, sid, 1);
117}
118
119int sidtab_map(struct sidtab *s,
120 int (*apply) (u32 sid,
121 struct context *context,
122 void *args),
123 void *args)
124{
125 int i, rc = 0;
126 struct sidtab_node *cur;
127
128 if (!s)
129 goto out;
130
131 for (i = 0; i < SIDTAB_SIZE; i++) {
132 cur = s->htable[i];
133 while (cur) {
134 rc = apply(cur->sid, &cur->context, args);
135 if (rc)
136 goto out;
137 cur = cur->next;
138 }
139 }
140out:
141 return rc;
142}
143
144static void sidtab_update_cache(struct sidtab *s, struct sidtab_node *n, int loc)
145{
146 BUG_ON(loc >= SIDTAB_CACHE_LEN);
147
148 while (loc > 0) {
149 s->cache[loc] = s->cache[loc - 1];
150 loc--;
151 }
152 s->cache[0] = n;
153}
154
155static inline u32 sidtab_search_context(struct sidtab *s,
156 struct context *context)
157{
158 int i;
159 struct sidtab_node *cur;
160
161 for (i = 0; i < SIDTAB_SIZE; i++) {
162 cur = s->htable[i];
163 while (cur) {
164 if (context_cmp(&cur->context, context)) {
165 sidtab_update_cache(s, cur, SIDTAB_CACHE_LEN - 1);
166 return cur->sid;
167 }
168 cur = cur->next;
169 }
170 }
171 return 0;
172}
173
174static inline u32 sidtab_search_cache(struct sidtab *s, struct context *context)
175{
176 int i;
177 struct sidtab_node *node;
178
179 for (i = 0; i < SIDTAB_CACHE_LEN; i++) {
180 node = s->cache[i];
181 if (unlikely(!node))
182 return 0;
183 if (context_cmp(&node->context, context)) {
184 sidtab_update_cache(s, node, i);
185 return node->sid;
186 }
187 }
188 return 0;
189}
190
191int sidtab_context_to_sid(struct sidtab *s,
192 struct context *context,
193 u32 *out_sid)
194{
195 u32 sid;
196 int ret = 0;
197 unsigned long flags;
198
199 *out_sid = SECSID_NULL;
200
201 sid = sidtab_search_cache(s, context);
202 if (!sid)
203 sid = sidtab_search_context(s, context);
204 if (!sid) {
205 spin_lock_irqsave(&s->lock, flags);
206 /* Rescan now that we hold the lock. */
207 sid = sidtab_search_context(s, context);
208 if (sid)
209 goto unlock_out;
210 /* No SID exists for the context. Allocate a new one. */
211 if (s->next_sid == UINT_MAX || s->shutdown) {
212 ret = -ENOMEM;
213 goto unlock_out;
214 }
215 sid = s->next_sid++;
216 if (context->len)
217 printk(KERN_INFO
218 "SELinux: Context %s is not valid (left unmapped).\n",
219 context->str);
220 ret = sidtab_insert(s, sid, context);
221 if (ret)
222 s->next_sid--;
223unlock_out:
224 spin_unlock_irqrestore(&s->lock, flags);
225 }
226
227 if (ret)
228 return ret;
229
230 *out_sid = sid;
231 return 0;
232}
233
234void sidtab_hash_eval(struct sidtab *h, char *tag)
235{
236 int i, chain_len, slots_used, max_chain_len;
237 struct sidtab_node *cur;
238
239 slots_used = 0;
240 max_chain_len = 0;
241 for (i = 0; i < SIDTAB_SIZE; i++) {
242 cur = h->htable[i];
243 if (cur) {
244 slots_used++;
245 chain_len = 0;
246 while (cur) {
247 chain_len++;
248 cur = cur->next;
249 }
250
251 if (chain_len > max_chain_len)
252 max_chain_len = chain_len;
253 }
254 }
255
256 printk(KERN_DEBUG "%s: %d entries and %d/%d buckets used, longest "
257 "chain length %d\n", tag, h->nel, slots_used, SIDTAB_SIZE,
258 max_chain_len);
259}
260
261void sidtab_destroy(struct sidtab *s)
262{
263 int i;
264 struct sidtab_node *cur, *temp;
265
266 if (!s)
267 return;
268
269 for (i = 0; i < SIDTAB_SIZE; i++) {
270 cur = s->htable[i];
271 while (cur) {
272 temp = cur;
273 cur = cur->next;
274 context_destroy(&temp->context);
275 kfree(temp);
276 }
277 s->htable[i] = NULL;
278 }
279 kfree(s->htable);
280 s->htable = NULL;
281 s->nel = 0;
282 s->next_sid = 1;
283}
284
285void sidtab_set(struct sidtab *dst, struct sidtab *src)
286{
287 unsigned long flags;
288 int i;
289
290 spin_lock_irqsave(&src->lock, flags);
291 dst->htable = src->htable;
292 dst->nel = src->nel;
293 dst->next_sid = src->next_sid;
294 dst->shutdown = 0;
295 for (i = 0; i < SIDTAB_CACHE_LEN; i++)
296 dst->cache[i] = NULL;
297 spin_unlock_irqrestore(&src->lock, flags);
298}
299
300void sidtab_shutdown(struct sidtab *s)
301{
302 unsigned long flags;
303
304 spin_lock_irqsave(&s->lock, flags);
305 s->shutdown = 1;
306 spin_unlock_irqrestore(&s->lock, flags);
307}
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Implementation of the SID table type.
4 *
5 * Original author: Stephen Smalley, <stephen.smalley.work@gmail.com>
6 * Author: Ondrej Mosnacek, <omosnacek@gmail.com>
7 *
8 * Copyright (C) 2018 Red Hat, Inc.
9 */
10
11#include <linux/errno.h>
12#include <linux/kernel.h>
13#include <linux/list.h>
14#include <linux/rcupdate.h>
15#include <linux/slab.h>
16#include <linux/sched.h>
17#include <linux/spinlock.h>
18#include <asm/barrier.h>
19#include "flask.h"
20#include "security.h"
21#include "sidtab.h"
22#include "services.h"
23
24struct sidtab_str_cache {
25 struct rcu_head rcu_member;
26 struct list_head lru_member;
27 struct sidtab_entry *parent;
28 u32 len;
29 char str[] __counted_by(len);
30};
31
32#define index_to_sid(index) ((index) + SECINITSID_NUM + 1)
33#define sid_to_index(sid) ((sid) - (SECINITSID_NUM + 1))
34
35int sidtab_init(struct sidtab *s)
36{
37 u32 i;
38
39 memset(s->roots, 0, sizeof(s->roots));
40
41 for (i = 0; i < SECINITSID_NUM; i++)
42 s->isids[i].set = 0;
43
44 s->frozen = false;
45 s->count = 0;
46 s->convert = NULL;
47 hash_init(s->context_to_sid);
48
49 spin_lock_init(&s->lock);
50
51#if CONFIG_SECURITY_SELINUX_SID2STR_CACHE_SIZE > 0
52 s->cache_free_slots = CONFIG_SECURITY_SELINUX_SID2STR_CACHE_SIZE;
53 INIT_LIST_HEAD(&s->cache_lru_list);
54 spin_lock_init(&s->cache_lock);
55#endif
56
57 return 0;
58}
59
60static u32 context_to_sid(struct sidtab *s, struct context *context, u32 hash)
61{
62 struct sidtab_entry *entry;
63 u32 sid = 0;
64
65 rcu_read_lock();
66 hash_for_each_possible_rcu(s->context_to_sid, entry, list, hash) {
67 if (entry->hash != hash)
68 continue;
69 if (context_cmp(&entry->context, context)) {
70 sid = entry->sid;
71 break;
72 }
73 }
74 rcu_read_unlock();
75 return sid;
76}
77
78int sidtab_set_initial(struct sidtab *s, u32 sid, struct context *context)
79{
80 struct sidtab_isid_entry *isid;
81 u32 hash;
82 int rc;
83
84 if (sid == 0 || sid > SECINITSID_NUM)
85 return -EINVAL;
86
87 isid = &s->isids[sid - 1];
88
89 rc = context_cpy(&isid->entry.context, context);
90 if (rc)
91 return rc;
92
93#if CONFIG_SECURITY_SELINUX_SID2STR_CACHE_SIZE > 0
94 isid->entry.cache = NULL;
95#endif
96 isid->set = 1;
97
98 hash = context_compute_hash(context);
99
100 /*
101 * Multiple initial sids may map to the same context. Check that this
102 * context is not already represented in the context_to_sid hashtable
103 * to avoid duplicate entries and long linked lists upon hash
104 * collision.
105 */
106 if (!context_to_sid(s, context, hash)) {
107 isid->entry.sid = sid;
108 isid->entry.hash = hash;
109 hash_add(s->context_to_sid, &isid->entry.list, hash);
110 }
111
112 return 0;
113}
114
115int sidtab_hash_stats(struct sidtab *sidtab, char *page)
116{
117 int i;
118 int chain_len = 0;
119 int slots_used = 0;
120 int entries = 0;
121 int max_chain_len = 0;
122 int cur_bucket = 0;
123 struct sidtab_entry *entry;
124
125 rcu_read_lock();
126 hash_for_each_rcu(sidtab->context_to_sid, i, entry, list) {
127 entries++;
128 if (i == cur_bucket) {
129 chain_len++;
130 if (chain_len == 1)
131 slots_used++;
132 } else {
133 cur_bucket = i;
134 if (chain_len > max_chain_len)
135 max_chain_len = chain_len;
136 chain_len = 0;
137 }
138 }
139 rcu_read_unlock();
140
141 if (chain_len > max_chain_len)
142 max_chain_len = chain_len;
143
144 return scnprintf(page, PAGE_SIZE,
145 "entries: %d\nbuckets used: %d/%d\n"
146 "longest chain: %d\n",
147 entries, slots_used, SIDTAB_HASH_BUCKETS,
148 max_chain_len);
149}
150
151static u32 sidtab_level_from_count(u32 count)
152{
153 u32 capacity = SIDTAB_LEAF_ENTRIES;
154 u32 level = 0;
155
156 while (count > capacity) {
157 capacity <<= SIDTAB_INNER_SHIFT;
158 ++level;
159 }
160 return level;
161}
162
163static int sidtab_alloc_roots(struct sidtab *s, u32 level)
164{
165 u32 l;
166
167 if (!s->roots[0].ptr_leaf) {
168 s->roots[0].ptr_leaf =
169 kzalloc(SIDTAB_NODE_ALLOC_SIZE, GFP_ATOMIC);
170 if (!s->roots[0].ptr_leaf)
171 return -ENOMEM;
172 }
173 for (l = 1; l <= level; ++l)
174 if (!s->roots[l].ptr_inner) {
175 s->roots[l].ptr_inner =
176 kzalloc(SIDTAB_NODE_ALLOC_SIZE, GFP_ATOMIC);
177 if (!s->roots[l].ptr_inner)
178 return -ENOMEM;
179 s->roots[l].ptr_inner->entries[0] = s->roots[l - 1];
180 }
181 return 0;
182}
183
184static struct sidtab_entry *sidtab_do_lookup(struct sidtab *s, u32 index,
185 int alloc)
186{
187 union sidtab_entry_inner *entry;
188 u32 level, capacity_shift, leaf_index = index / SIDTAB_LEAF_ENTRIES;
189
190 /* find the level of the subtree we need */
191 level = sidtab_level_from_count(index + 1);
192 capacity_shift = level * SIDTAB_INNER_SHIFT;
193
194 /* allocate roots if needed */
195 if (alloc && sidtab_alloc_roots(s, level) != 0)
196 return NULL;
197
198 /* lookup inside the subtree */
199 entry = &s->roots[level];
200 while (level != 0) {
201 capacity_shift -= SIDTAB_INNER_SHIFT;
202 --level;
203
204 entry = &entry->ptr_inner->entries[leaf_index >> capacity_shift];
205 leaf_index &= ((u32)1 << capacity_shift) - 1;
206
207 if (!entry->ptr_inner) {
208 if (alloc)
209 entry->ptr_inner = kzalloc(
210 SIDTAB_NODE_ALLOC_SIZE, GFP_ATOMIC);
211 if (!entry->ptr_inner)
212 return NULL;
213 }
214 }
215 if (!entry->ptr_leaf) {
216 if (alloc)
217 entry->ptr_leaf =
218 kzalloc(SIDTAB_NODE_ALLOC_SIZE, GFP_ATOMIC);
219 if (!entry->ptr_leaf)
220 return NULL;
221 }
222 return &entry->ptr_leaf->entries[index % SIDTAB_LEAF_ENTRIES];
223}
224
225static struct sidtab_entry *sidtab_lookup(struct sidtab *s, u32 index)
226{
227 /* read entries only after reading count */
228 u32 count = smp_load_acquire(&s->count);
229
230 if (index >= count)
231 return NULL;
232
233 return sidtab_do_lookup(s, index, 0);
234}
235
236static struct sidtab_entry *sidtab_lookup_initial(struct sidtab *s, u32 sid)
237{
238 return s->isids[sid - 1].set ? &s->isids[sid - 1].entry : NULL;
239}
240
241static struct sidtab_entry *sidtab_search_core(struct sidtab *s, u32 sid,
242 int force)
243{
244 if (sid != 0) {
245 struct sidtab_entry *entry;
246
247 if (sid > SECINITSID_NUM)
248 entry = sidtab_lookup(s, sid_to_index(sid));
249 else
250 entry = sidtab_lookup_initial(s, sid);
251 if (entry && (!entry->context.len || force))
252 return entry;
253 }
254
255 return sidtab_lookup_initial(s, SECINITSID_UNLABELED);
256}
257
258struct sidtab_entry *sidtab_search_entry(struct sidtab *s, u32 sid)
259{
260 return sidtab_search_core(s, sid, 0);
261}
262
263struct sidtab_entry *sidtab_search_entry_force(struct sidtab *s, u32 sid)
264{
265 return sidtab_search_core(s, sid, 1);
266}
267
268int sidtab_context_to_sid(struct sidtab *s, struct context *context, u32 *sid)
269{
270 unsigned long flags;
271 u32 count, hash = context_compute_hash(context);
272 struct sidtab_convert_params *convert;
273 struct sidtab_entry *dst, *dst_convert;
274 int rc;
275
276 *sid = context_to_sid(s, context, hash);
277 if (*sid)
278 return 0;
279
280 /* lock-free search failed: lock, re-search, and insert if not found */
281 spin_lock_irqsave(&s->lock, flags);
282
283 rc = 0;
284 *sid = context_to_sid(s, context, hash);
285 if (*sid)
286 goto out_unlock;
287
288 if (unlikely(s->frozen)) {
289 /*
290 * This sidtab is now frozen - tell the caller to abort and
291 * get the new one.
292 */
293 rc = -ESTALE;
294 goto out_unlock;
295 }
296
297 count = s->count;
298
299 /* bail out if we already reached max entries */
300 rc = -EOVERFLOW;
301 if (count >= SIDTAB_MAX)
302 goto out_unlock;
303
304 /* insert context into new entry */
305 rc = -ENOMEM;
306 dst = sidtab_do_lookup(s, count, 1);
307 if (!dst)
308 goto out_unlock;
309
310 dst->sid = index_to_sid(count);
311 dst->hash = hash;
312
313 rc = context_cpy(&dst->context, context);
314 if (rc)
315 goto out_unlock;
316
317 /*
318 * if we are building a new sidtab, we need to convert the context
319 * and insert it there as well
320 */
321 convert = s->convert;
322 if (convert) {
323 struct sidtab *target = convert->target;
324
325 rc = -ENOMEM;
326 dst_convert = sidtab_do_lookup(target, count, 1);
327 if (!dst_convert) {
328 context_destroy(&dst->context);
329 goto out_unlock;
330 }
331
332 rc = services_convert_context(convert->args, context,
333 &dst_convert->context,
334 GFP_ATOMIC);
335 if (rc) {
336 context_destroy(&dst->context);
337 goto out_unlock;
338 }
339 dst_convert->sid = index_to_sid(count);
340 dst_convert->hash = context_compute_hash(&dst_convert->context);
341 target->count = count + 1;
342
343 hash_add_rcu(target->context_to_sid, &dst_convert->list,
344 dst_convert->hash);
345 }
346
347 if (context->len)
348 pr_info("SELinux: Context %s is not valid (left unmapped).\n",
349 context->str);
350
351 *sid = index_to_sid(count);
352
353 /* write entries before updating count */
354 smp_store_release(&s->count, count + 1);
355 hash_add_rcu(s->context_to_sid, &dst->list, dst->hash);
356
357 rc = 0;
358out_unlock:
359 spin_unlock_irqrestore(&s->lock, flags);
360 return rc;
361}
362
363static void sidtab_convert_hashtable(struct sidtab *s, u32 count)
364{
365 struct sidtab_entry *entry;
366 u32 i;
367
368 for (i = 0; i < count; i++) {
369 entry = sidtab_do_lookup(s, i, 0);
370 entry->sid = index_to_sid(i);
371 entry->hash = context_compute_hash(&entry->context);
372
373 hash_add_rcu(s->context_to_sid, &entry->list, entry->hash);
374 }
375}
376
377static int sidtab_convert_tree(union sidtab_entry_inner *edst,
378 union sidtab_entry_inner *esrc, u32 *pos,
379 u32 count, u32 level,
380 struct sidtab_convert_params *convert)
381{
382 int rc;
383 u32 i;
384
385 if (level != 0) {
386 if (!edst->ptr_inner) {
387 edst->ptr_inner =
388 kzalloc(SIDTAB_NODE_ALLOC_SIZE, GFP_KERNEL);
389 if (!edst->ptr_inner)
390 return -ENOMEM;
391 }
392 i = 0;
393 while (i < SIDTAB_INNER_ENTRIES && *pos < count) {
394 rc = sidtab_convert_tree(&edst->ptr_inner->entries[i],
395 &esrc->ptr_inner->entries[i],
396 pos, count, level - 1,
397 convert);
398 if (rc)
399 return rc;
400 i++;
401 }
402 } else {
403 if (!edst->ptr_leaf) {
404 edst->ptr_leaf =
405 kzalloc(SIDTAB_NODE_ALLOC_SIZE, GFP_KERNEL);
406 if (!edst->ptr_leaf)
407 return -ENOMEM;
408 }
409 i = 0;
410 while (i < SIDTAB_LEAF_ENTRIES && *pos < count) {
411 rc = services_convert_context(
412 convert->args,
413 &esrc->ptr_leaf->entries[i].context,
414 &edst->ptr_leaf->entries[i].context,
415 GFP_KERNEL);
416 if (rc)
417 return rc;
418 (*pos)++;
419 i++;
420 }
421 cond_resched();
422 }
423 return 0;
424}
425
426int sidtab_convert(struct sidtab *s, struct sidtab_convert_params *params)
427{
428 unsigned long flags;
429 u32 count, level, pos;
430 int rc;
431
432 spin_lock_irqsave(&s->lock, flags);
433
434 /* concurrent policy loads are not allowed */
435 if (s->convert) {
436 spin_unlock_irqrestore(&s->lock, flags);
437 return -EBUSY;
438 }
439
440 count = s->count;
441 level = sidtab_level_from_count(count);
442
443 /* allocate last leaf in the new sidtab (to avoid race with
444 * live convert)
445 */
446 rc = sidtab_do_lookup(params->target, count - 1, 1) ? 0 : -ENOMEM;
447 if (rc) {
448 spin_unlock_irqrestore(&s->lock, flags);
449 return rc;
450 }
451
452 /* set count in case no new entries are added during conversion */
453 params->target->count = count;
454
455 /* enable live convert of new entries */
456 s->convert = params;
457
458 /* we can safely convert the tree outside the lock */
459 spin_unlock_irqrestore(&s->lock, flags);
460
461 pr_info("SELinux: Converting %u SID table entries...\n", count);
462
463 /* convert all entries not covered by live convert */
464 pos = 0;
465 rc = sidtab_convert_tree(¶ms->target->roots[level],
466 &s->roots[level], &pos, count, level, params);
467 if (rc) {
468 /* we need to keep the old table - disable live convert */
469 spin_lock_irqsave(&s->lock, flags);
470 s->convert = NULL;
471 spin_unlock_irqrestore(&s->lock, flags);
472 return rc;
473 }
474 /*
475 * The hashtable can also be modified in sidtab_context_to_sid()
476 * so we must re-acquire the lock here.
477 */
478 spin_lock_irqsave(&s->lock, flags);
479 sidtab_convert_hashtable(params->target, count);
480 spin_unlock_irqrestore(&s->lock, flags);
481
482 return 0;
483}
484
485void sidtab_cancel_convert(struct sidtab *s)
486{
487 unsigned long flags;
488
489 /* cancelling policy load - disable live convert of sidtab */
490 spin_lock_irqsave(&s->lock, flags);
491 s->convert = NULL;
492 spin_unlock_irqrestore(&s->lock, flags);
493}
494
495void sidtab_freeze_begin(struct sidtab *s, unsigned long *flags)
496 __acquires(&s->lock)
497{
498 spin_lock_irqsave(&s->lock, *flags);
499 s->frozen = true;
500 s->convert = NULL;
501}
502void sidtab_freeze_end(struct sidtab *s, unsigned long *flags)
503 __releases(&s->lock)
504{
505 spin_unlock_irqrestore(&s->lock, *flags);
506}
507
508static void sidtab_destroy_entry(struct sidtab_entry *entry)
509{
510 context_destroy(&entry->context);
511#if CONFIG_SECURITY_SELINUX_SID2STR_CACHE_SIZE > 0
512 kfree(rcu_dereference_raw(entry->cache));
513#endif
514}
515
516static void sidtab_destroy_tree(union sidtab_entry_inner entry, u32 level)
517{
518 u32 i;
519
520 if (level != 0) {
521 struct sidtab_node_inner *node = entry.ptr_inner;
522
523 if (!node)
524 return;
525
526 for (i = 0; i < SIDTAB_INNER_ENTRIES; i++)
527 sidtab_destroy_tree(node->entries[i], level - 1);
528 kfree(node);
529 } else {
530 struct sidtab_node_leaf *node = entry.ptr_leaf;
531
532 if (!node)
533 return;
534
535 for (i = 0; i < SIDTAB_LEAF_ENTRIES; i++)
536 sidtab_destroy_entry(&node->entries[i]);
537 kfree(node);
538 }
539}
540
541void sidtab_destroy(struct sidtab *s)
542{
543 u32 i, level;
544
545 for (i = 0; i < SECINITSID_NUM; i++)
546 if (s->isids[i].set)
547 sidtab_destroy_entry(&s->isids[i].entry);
548
549 level = SIDTAB_MAX_LEVEL;
550 while (level && !s->roots[level].ptr_inner)
551 --level;
552
553 sidtab_destroy_tree(s->roots[level], level);
554 /*
555 * The context_to_sid hashtable's objects are all shared
556 * with the isids array and context tree, and so don't need
557 * to be cleaned up here.
558 */
559}
560
561#if CONFIG_SECURITY_SELINUX_SID2STR_CACHE_SIZE > 0
562
563void sidtab_sid2str_put(struct sidtab *s, struct sidtab_entry *entry,
564 const char *str, u32 str_len)
565{
566 struct sidtab_str_cache *cache, *victim = NULL;
567 unsigned long flags;
568
569 /* do not cache invalid contexts */
570 if (entry->context.len)
571 return;
572
573 spin_lock_irqsave(&s->cache_lock, flags);
574
575 cache = rcu_dereference_protected(entry->cache,
576 lockdep_is_held(&s->cache_lock));
577 if (cache) {
578 /* entry in cache - just bump to the head of LRU list */
579 list_move(&cache->lru_member, &s->cache_lru_list);
580 goto out_unlock;
581 }
582
583 cache = kmalloc(struct_size(cache, str, str_len), GFP_ATOMIC);
584 if (!cache)
585 goto out_unlock;
586
587 if (s->cache_free_slots == 0) {
588 /* pop a cache entry from the tail and free it */
589 victim = container_of(s->cache_lru_list.prev,
590 struct sidtab_str_cache, lru_member);
591 list_del(&victim->lru_member);
592 rcu_assign_pointer(victim->parent->cache, NULL);
593 } else {
594 s->cache_free_slots--;
595 }
596 cache->parent = entry;
597 cache->len = str_len;
598 memcpy(cache->str, str, str_len);
599 list_add(&cache->lru_member, &s->cache_lru_list);
600
601 rcu_assign_pointer(entry->cache, cache);
602
603out_unlock:
604 spin_unlock_irqrestore(&s->cache_lock, flags);
605 kfree_rcu(victim, rcu_member);
606}
607
608int sidtab_sid2str_get(struct sidtab *s, struct sidtab_entry *entry, char **out,
609 u32 *out_len)
610{
611 struct sidtab_str_cache *cache;
612 int rc = 0;
613
614 if (entry->context.len)
615 return -ENOENT; /* do not cache invalid contexts */
616
617 rcu_read_lock();
618
619 cache = rcu_dereference(entry->cache);
620 if (!cache) {
621 rc = -ENOENT;
622 } else {
623 *out_len = cache->len;
624 if (out) {
625 *out = kmemdup(cache->str, cache->len, GFP_ATOMIC);
626 if (!*out)
627 rc = -ENOMEM;
628 }
629 }
630
631 rcu_read_unlock();
632
633 if (!rc && out)
634 sidtab_sid2str_put(s, entry, *out, *out_len);
635 return rc;
636}
637
638#endif /* CONFIG_SECURITY_SELINUX_SID2STR_CACHE_SIZE > 0 */