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2024-05-10 cde9070d9970eef1f7ec2360586c802a16230ad8 
 kernel/security/selinux/ss/sidtab.c
....@@ -9,6 +9,8 @@
99  */
1010 #include <linux/errno.h>
1111 #include <linux/kernel.h>
12
+#include <linux/list.h>
13
+#include <linux/rcupdate.h>
1214 #include <linux/slab.h>
1315 #include <linux/sched.h>
1416 #include <linux/spinlock.h>
....@@ -16,6 +18,14 @@
1618 #include "flask.h"
1719 #include "security.h"
1820 #include "sidtab.h"
21
+
22
+struct 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
+};
1929 
2030 #define index_to_sid(index) (index + SECINITSID_NUM + 1)
2131 #define sid_to_index(sid) (sid - (SECINITSID_NUM + 1))
....@@ -29,22 +39,31 @@
2939 	for (i = 0; i < SECINITSID_NUM; i++)
3040 		s->isids[i].set = 0;
3141 
42
+	s->frozen = false;
3243 	s->count = 0;
3344 	s->convert = NULL;
3445 	hash_init(s->context_to_sid);
3546 
3647 	spin_lock_init(&s->lock);
48
+
49
+#if CONFIG_SECURITY_SELINUX_SID2STR_CACHE_SIZE > 0
50
+	s->cache_free_slots = CONFIG_SECURITY_SELINUX_SID2STR_CACHE_SIZE;
51
+	INIT_LIST_HEAD(&s->cache_lru_list);
52
+	spin_lock_init(&s->cache_lock);
53
+#endif
54
+
3755 	return 0;
3856 }
3957 
40
-static u32 context_to_sid(struct sidtab *s, struct context *context)
58
+static u32 context_to_sid(struct sidtab *s, struct context *context, u32 hash)
4159 {
42
-	struct sidtab_entry_leaf *entry;
60
+	struct sidtab_entry *entry;
4361 	u32 sid = 0;
4462 
4563 	rcu_read_lock();
46
-	hash_for_each_possible_rcu(s->context_to_sid, entry, list,
47
-				   context->hash) {
64
+	hash_for_each_possible_rcu(s->context_to_sid, entry, list, hash) {
65
+		if (entry->hash != hash)
66
+			continue;
4867 		if (context_cmp(&entry->context, context)) {
4968 			sid = entry->sid;
5069 			break;
....@@ -56,19 +75,25 @@
5675 
5776 int sidtab_set_initial(struct sidtab *s, u32 sid, struct context *context)
5877 {
59
-	struct sidtab_isid_entry *entry;
78
+	struct sidtab_isid_entry *isid;
79
+	u32 hash;
6080 	int rc;
6181 
6282 	if (sid == 0 || sid > SECINITSID_NUM)
6383 		return -EINVAL;
6484 
65
-	entry = &s->isids[sid - 1];
85
+	isid = &s->isids[sid - 1];
6686 
67
-	rc = context_cpy(&entry->leaf.context, context);
87
+	rc = context_cpy(&isid->entry.context, context);
6888 	if (rc)
6989 		return rc;
7090 
71
-	entry->set = 1;
91
+#if CONFIG_SECURITY_SELINUX_SID2STR_CACHE_SIZE > 0
92
+	isid->entry.cache = NULL;
93
+#endif
94
+	isid->set = 1;
95
+
96
+	hash = context_compute_hash(context);
7297 
7398 	/*
7499 	 * Multiple initial sids may map to the same context. Check that this
....@@ -76,9 +101,10 @@
76101 	 * to avoid duplicate entries and long linked lists upon hash
77102 	 * collision.
78103 	 */
79
-	if (!context_to_sid(s, context)) {
80
-		entry->leaf.sid = sid;
81
-		hash_add(s->context_to_sid, &entry->leaf.list, context->hash);
104
+	if (!context_to_sid(s, context, hash)) {
105
+		isid->entry.sid = sid;
106
+		isid->entry.hash = hash;
107
+		hash_add(s->context_to_sid, &isid->entry.list, hash);
82108 	}
83109 
84110 	return 0;
....@@ -92,7 +118,7 @@
92118 	int entries = 0;
93119 	int max_chain_len = 0;
94120 	int cur_bucket = 0;
95
-	struct sidtab_entry_leaf *entry;
121
+	struct sidtab_entry *entry;
96122 
97123 	rcu_read_lock();
98124 	hash_for_each_rcu(sidtab->context_to_sid, i, entry, list) {
....@@ -151,8 +177,8 @@
151177 	return 0;
152178 }
153179 
154
-static struct sidtab_entry_leaf *sidtab_do_lookup(struct sidtab *s, u32 index,
155
-						  int alloc)
180
+static struct sidtab_entry *sidtab_do_lookup(struct sidtab *s, u32 index,
181
+					     int alloc)
156182 {
157183 	union sidtab_entry_inner *entry;
158184 	u32 level, capacity_shift, leaf_index = index / SIDTAB_LEAF_ENTRIES;
....@@ -192,7 +218,7 @@
192218 	return &entry->ptr_leaf->entries[index % SIDTAB_LEAF_ENTRIES];
193219 }
194220 
195
-static struct context *sidtab_lookup(struct sidtab *s, u32 index)
221
+static struct sidtab_entry *sidtab_lookup(struct sidtab *s, u32 index)
196222 {
197223 	/* read entries only after reading count */
198224 	u32 count = smp_load_acquire(&s->count);
....@@ -200,36 +226,37 @@
200226 	if (index >= count)
201227 		return NULL;
202228 
203
-	return &sidtab_do_lookup(s, index, 0)->context;
229
+	return sidtab_do_lookup(s, index, 0);
204230 }
205231 
206
-static struct context *sidtab_lookup_initial(struct sidtab *s, u32 sid)
232
+static struct sidtab_entry *sidtab_lookup_initial(struct sidtab *s, u32 sid)
207233 {
208
-	return s->isids[sid - 1].set ? &s->isids[sid - 1].leaf.context : NULL;
234
+	return s->isids[sid - 1].set ? &s->isids[sid - 1].entry : NULL;
209235 }
210236 
211
-static struct context *sidtab_search_core(struct sidtab *s, u32 sid, int force)
237
+static struct sidtab_entry *sidtab_search_core(struct sidtab *s, u32 sid,
238
+					       int force)
212239 {
213
-	struct context *context;
214
-
215240 	if (sid != 0) {
241
+		struct sidtab_entry *entry;
242
+
216243 		if (sid > SECINITSID_NUM)
217
-			context = sidtab_lookup(s, sid_to_index(sid));
244
+			entry = sidtab_lookup(s, sid_to_index(sid));
218245 		else
219
-			context = sidtab_lookup_initial(s, sid);
220
-		if (context && (!context->len || force))
221
-			return context;
246
+			entry = sidtab_lookup_initial(s, sid);
247
+		if (entry && (!entry->context.len || force))
248
+			return entry;
222249 	}
223250 
224251 	return sidtab_lookup_initial(s, SECINITSID_UNLABELED);
225252 }
226253 
227
-struct context *sidtab_search(struct sidtab *s, u32 sid)
254
+struct sidtab_entry *sidtab_search_entry(struct sidtab *s, u32 sid)
228255 {
229256 	return sidtab_search_core(s, sid, 0);
230257 }
231258 
232
-struct context *sidtab_search_force(struct sidtab *s, u32 sid)
259
+struct sidtab_entry *sidtab_search_entry_force(struct sidtab *s, u32 sid)
233260 {
234261 	return sidtab_search_core(s, sid, 1);
235262 }
....@@ -238,12 +265,12 @@
238265 			  u32 *sid)
239266 {
240267 	unsigned long flags;
241
-	u32 count;
268
+	u32 count, hash = context_compute_hash(context);
242269 	struct sidtab_convert_params *convert;
243
-	struct sidtab_entry_leaf *dst, *dst_convert;
270
+	struct sidtab_entry *dst, *dst_convert;
244271 	int rc;
245272 
246
-	*sid = context_to_sid(s, context);
273
+	*sid = context_to_sid(s, context, hash);
247274 	if (*sid)
248275 		return 0;
249276 
....@@ -251,12 +278,20 @@
251278 	spin_lock_irqsave(&s->lock, flags);
252279 
253280 	rc = 0;
254
-	*sid = context_to_sid(s, context);
281
+	*sid = context_to_sid(s, context, hash);
255282 	if (*sid)
256283 		goto out_unlock;
257284 
258
-	/* read entries only after reading count */
259
-	count = smp_load_acquire(&s->count);
285
+	if (unlikely(s->frozen)) {
286
+		/*
287
+		 * This sidtab is now frozen - tell the caller to abort and
288
+		 * get the new one.
289
+		 */
290
+		rc = -ESTALE;
291
+		goto out_unlock;
292
+	}
293
+
294
+	count = s->count;
260295 	convert = s->convert;
261296 
262297 	/* bail out if we already reached max entries */
....@@ -271,6 +306,7 @@
271306 		goto out_unlock;
272307 
273308 	dst->sid = index_to_sid(count);
309
+	dst->hash = hash;
274310 
275311 	rc = context_cpy(&dst->context, context);
276312 	if (rc)
....@@ -289,16 +325,17 @@
289325 		}
290326 
291327 		rc = convert->func(context, &dst_convert->context,
292
-				convert->args);
328
+				   convert->args, GFP_ATOMIC);
293329 		if (rc) {
294330 			context_destroy(&dst->context);
295331 			goto out_unlock;
296332 		}
297333 		dst_convert->sid = index_to_sid(count);
334
+		dst_convert->hash = context_compute_hash(&dst_convert->context);
298335 		convert->target->count = count + 1;
299336 
300337 		hash_add_rcu(convert->target->context_to_sid,
301
-				&dst_convert->list, dst_convert->context.hash);
338
+			     &dst_convert->list, dst_convert->hash);
302339 	}
303340 
304341 	if (context->len)
....@@ -309,7 +346,7 @@
309346 
310347 	/* write entries before updating count */
311348 	smp_store_release(&s->count, count + 1);
312
-	hash_add_rcu(s->context_to_sid, &dst->list, dst->context.hash);
349
+	hash_add_rcu(s->context_to_sid, &dst->list, dst->hash);
313350 
314351 	rc = 0;
315352 out_unlock:
....@@ -319,16 +356,15 @@
319356 
320357 static void sidtab_convert_hashtable(struct sidtab *s, u32 count)
321358 {
322
-	struct sidtab_entry_leaf *entry;
359
+	struct sidtab_entry *entry;
323360 	u32 i;
324361 
325362 	for (i = 0; i < count; i++) {
326363 		entry = sidtab_do_lookup(s, i, 0);
327364 		entry->sid = index_to_sid(i);
365
+		entry->hash = context_compute_hash(&entry->context);
328366 
329
-		hash_add_rcu(s->context_to_sid, &entry->list,
330
-				entry->context.hash);
331
-
367
+		hash_add_rcu(s->context_to_sid, &entry->list, entry->hash);
332368 	}
333369 }
334370 
....@@ -368,7 +404,7 @@
368404 		while (i < SIDTAB_LEAF_ENTRIES && *pos < count) {
369405 			rc = convert->func(&esrc->ptr_leaf->entries[i].context,
370406 					   &edst->ptr_leaf->entries[i].context,
371
-					   convert->args);
407
+					   convert->args, GFP_KERNEL);
372408 			if (rc)
373409 				return rc;
374410 			(*pos)++;
....@@ -376,7 +412,6 @@
376412 		}
377413 		cond_resched();
378414 	}
379
-
380415 	return 0;
381416 }
382417 
....@@ -439,6 +474,35 @@
439474 	return 0;
440475 }
441476 
477
+void sidtab_cancel_convert(struct sidtab *s)
478
+{
479
+	unsigned long flags;
480
+
481
+	/* cancelling policy load - disable live convert of sidtab */
482
+	spin_lock_irqsave(&s->lock, flags);
483
+	s->convert = NULL;
484
+	spin_unlock_irqrestore(&s->lock, flags);
485
+}
486
+
487
+void sidtab_freeze_begin(struct sidtab *s, unsigned long *flags) __acquires(&s->lock)
488
+{
489
+	spin_lock_irqsave(&s->lock, *flags);
490
+	s->frozen = true;
491
+	s->convert = NULL;
492
+}
493
+void sidtab_freeze_end(struct sidtab *s, unsigned long *flags) __releases(&s->lock)
494
+{
495
+	spin_unlock_irqrestore(&s->lock, *flags);
496
+}
497
+
498
+static void sidtab_destroy_entry(struct sidtab_entry *entry)
499
+{
500
+	context_destroy(&entry->context);
501
+#if CONFIG_SECURITY_SELINUX_SID2STR_CACHE_SIZE > 0
502
+	kfree(rcu_dereference_raw(entry->cache));
503
+#endif
504
+}
505
+
442506 static void sidtab_destroy_tree(union sidtab_entry_inner entry, u32 level)
443507 {
444508 	u32 i;
....@@ -459,7 +523,7 @@
459523 			return;
460524 
461525 		for (i = 0; i < SIDTAB_LEAF_ENTRIES; i++)
462
-			context_destroy(&node->entries[i].context);
526
+			sidtab_destroy_entry(&node->entries[i]);
463527 		kfree(node);
464528 	}
465529 }
....@@ -470,7 +534,7 @@
470534 
471535 	for (i = 0; i < SECINITSID_NUM; i++)
472536 		if (s->isids[i].set)
473
-			context_destroy(&s->isids[i].leaf.context);
537
+			sidtab_destroy_entry(&s->isids[i].entry);
474538 
475539 	level = SIDTAB_MAX_LEVEL;
476540 	while (level && !s->roots[level].ptr_inner)
....@@ -483,3 +547,82 @@
483547 	 * to be cleaned up here.
484548 	 */
485549 }
550
+
551
+#if CONFIG_SECURITY_SELINUX_SID2STR_CACHE_SIZE > 0
552
+
553
+void sidtab_sid2str_put(struct sidtab *s, struct sidtab_entry *entry,
554
+			const char *str, u32 str_len)
555
+{
556
+	struct sidtab_str_cache *cache, *victim = NULL;
557
+	unsigned long flags;
558
+
559
+	/* do not cache invalid contexts */
560
+	if (entry->context.len)
561
+		return;
562
+
563
+	spin_lock_irqsave(&s->cache_lock, flags);
564
+
565
+	cache = rcu_dereference_protected(entry->cache,
566
+					  lockdep_is_held(&s->cache_lock));
567
+	if (cache) {
568
+		/* entry in cache - just bump to the head of LRU list */
569
+		list_move(&cache->lru_member, &s->cache_lru_list);
570
+		goto out_unlock;
571
+	}
572
+
573
+	cache = kmalloc(sizeof(struct sidtab_str_cache) + str_len, GFP_ATOMIC);
574
+	if (!cache)
575
+		goto out_unlock;
576
+
577
+	if (s->cache_free_slots == 0) {
578
+		/* pop a cache entry from the tail and free it */
579
+		victim = container_of(s->cache_lru_list.prev,
580
+				      struct sidtab_str_cache, lru_member);
581
+		list_del(&victim->lru_member);
582
+		rcu_assign_pointer(victim->parent->cache, NULL);
583
+	} else {
584
+		s->cache_free_slots--;
585
+	}
586
+	cache->parent = entry;
587
+	cache->len = str_len;
588
+	memcpy(cache->str, str, str_len);
589
+	list_add(&cache->lru_member, &s->cache_lru_list);
590
+
591
+	rcu_assign_pointer(entry->cache, cache);
592
+
593
+out_unlock:
594
+	spin_unlock_irqrestore(&s->cache_lock, flags);
595
+	kfree_rcu(victim, rcu_member);
596
+}
597
+
598
+int sidtab_sid2str_get(struct sidtab *s, struct sidtab_entry *entry,
599
+		       char **out, u32 *out_len)
600
+{
601
+	struct sidtab_str_cache *cache;
602
+	int rc = 0;
603
+
604
+	if (entry->context.len)
605
+		return -ENOENT; /* do not cache invalid contexts */
606
+
607
+	rcu_read_lock();
608
+
609
+	cache = rcu_dereference(entry->cache);
610
+	if (!cache) {
611
+		rc = -ENOENT;
612
+	} else {
613
+		*out_len = cache->len;
614
+		if (out) {
615
+			*out = kmemdup(cache->str, cache->len, GFP_ATOMIC);
616
+			if (!*out)
617
+				rc = -ENOMEM;
618
+		}
619
+	}
620
+
621
+	rcu_read_unlock();
622
+
623
+	if (!rc && out)
624
+		sidtab_sid2str_put(s, entry, *out, *out_len);
625
+	return rc;
626
+}
627
+
628
+#endif /* CONFIG_SECURITY_SELINUX_SID2STR_CACHE_SIZE > 0 */