1 /*
2 * Implementation of the access vector table type.
3 *
4 * Author : Stephen Smalley, <stephen.smalley.work@gmail.com>
5 */
6
7 /* Updated: Frank Mayer <mayerf@tresys.com> and Karl MacMillan <kmacmillan@tresys.com>
8 *
9 * Added conditional policy language extensions
10 *
11 * Copyright (C) 2003 Tresys Technology, LLC
12 * This program is free software; you can redistribute it and/or modify
13 * it under the terms of the GNU General Public License as published by
14 * the Free Software Foundation, version 2.
15 *
16 * Updated: Yuichi Nakamura <ynakam@hitachisoft.jp>
17 * Tuned number of hash slots for avtab to reduce memory usage
18 */
19
20 #include <linux/kernel.h>
21 #include <linux/slab.h>
22 #include <linux/errno.h>
23 #include "avtab.h"
24 #include "policydb.h"
25
26 static struct kmem_cache *avtab_node_cachep __ro_after_init;
27 static struct kmem_cache *avtab_xperms_cachep __ro_after_init;
28
29 /* Based on MurmurHash3, written by Austin Appleby and placed in the
30 * public domain.
31 */
avtab_hash(const struct avtab_key * keyp,u32 mask)32 static inline u32 avtab_hash(const struct avtab_key *keyp, u32 mask)
33 {
34 static const u32 c1 = 0xcc9e2d51;
35 static const u32 c2 = 0x1b873593;
36 static const u32 r1 = 15;
37 static const u32 r2 = 13;
38 static const u32 m = 5;
39 static const u32 n = 0xe6546b64;
40
41 u32 hash = 0;
42
43 #define mix(input) do { \
44 u32 v = input; \
45 v *= c1; \
46 v = (v << r1) | (v >> (32 - r1)); \
47 v *= c2; \
48 hash ^= v; \
49 hash = (hash << r2) | (hash >> (32 - r2)); \
50 hash = hash * m + n; \
51 } while (0)
52
53 mix(keyp->target_class);
54 mix(keyp->target_type);
55 mix(keyp->source_type);
56
57 #undef mix
58
59 hash ^= hash >> 16;
60 hash *= 0x85ebca6b;
61 hash ^= hash >> 13;
62 hash *= 0xc2b2ae35;
63 hash ^= hash >> 16;
64
65 return hash & mask;
66 }
67
68 static struct avtab_node*
avtab_insert_node(struct avtab * h,u32 hvalue,struct avtab_node * prev,const struct avtab_key * key,const struct avtab_datum * datum)69 avtab_insert_node(struct avtab *h, u32 hvalue,
70 struct avtab_node *prev,
71 const struct avtab_key *key, const struct avtab_datum *datum)
72 {
73 struct avtab_node *newnode;
74 struct avtab_extended_perms *xperms;
75 newnode = kmem_cache_zalloc(avtab_node_cachep, GFP_KERNEL);
76 if (newnode == NULL)
77 return NULL;
78 newnode->key = *key;
79
80 if (key->specified & AVTAB_XPERMS) {
81 xperms = kmem_cache_zalloc(avtab_xperms_cachep, GFP_KERNEL);
82 if (xperms == NULL) {
83 kmem_cache_free(avtab_node_cachep, newnode);
84 return NULL;
85 }
86 *xperms = *(datum->u.xperms);
87 newnode->datum.u.xperms = xperms;
88 } else {
89 newnode->datum.u.data = datum->u.data;
90 }
91
92 if (prev) {
93 newnode->next = prev->next;
94 prev->next = newnode;
95 } else {
96 struct avtab_node **n = &h->htable[hvalue];
97
98 newnode->next = *n;
99 *n = newnode;
100 }
101
102 h->nel++;
103 return newnode;
104 }
105
avtab_insert(struct avtab * h,const struct avtab_key * key,const struct avtab_datum * datum)106 static int avtab_insert(struct avtab *h, const struct avtab_key *key,
107 const struct avtab_datum *datum)
108 {
109 u32 hvalue;
110 struct avtab_node *prev, *cur, *newnode;
111 u16 specified = key->specified & ~(AVTAB_ENABLED|AVTAB_ENABLED_OLD);
112
113 if (!h || !h->nslot || h->nel == U32_MAX)
114 return -EINVAL;
115
116 hvalue = avtab_hash(key, h->mask);
117 for (prev = NULL, cur = h->htable[hvalue];
118 cur;
119 prev = cur, cur = cur->next) {
120 if (key->source_type == cur->key.source_type &&
121 key->target_type == cur->key.target_type &&
122 key->target_class == cur->key.target_class &&
123 (specified & cur->key.specified)) {
124 /* extended perms may not be unique */
125 if (specified & AVTAB_XPERMS)
126 break;
127 return -EEXIST;
128 }
129 if (key->source_type < cur->key.source_type)
130 break;
131 if (key->source_type == cur->key.source_type &&
132 key->target_type < cur->key.target_type)
133 break;
134 if (key->source_type == cur->key.source_type &&
135 key->target_type == cur->key.target_type &&
136 key->target_class < cur->key.target_class)
137 break;
138 }
139
140 newnode = avtab_insert_node(h, hvalue, prev, key, datum);
141 if (!newnode)
142 return -ENOMEM;
143
144 return 0;
145 }
146
147 /* Unlike avtab_insert(), this function allow multiple insertions of the same
148 * key/specified mask into the table, as needed by the conditional avtab.
149 * It also returns a pointer to the node inserted.
150 */
avtab_insert_nonunique(struct avtab * h,const struct avtab_key * key,const struct avtab_datum * datum)151 struct avtab_node *avtab_insert_nonunique(struct avtab *h,
152 const struct avtab_key *key,
153 const struct avtab_datum *datum)
154 {
155 u32 hvalue;
156 struct avtab_node *prev, *cur;
157 u16 specified = key->specified & ~(AVTAB_ENABLED|AVTAB_ENABLED_OLD);
158
159 if (!h || !h->nslot || h->nel == U32_MAX)
160 return NULL;
161 hvalue = avtab_hash(key, h->mask);
162 for (prev = NULL, cur = h->htable[hvalue];
163 cur;
164 prev = cur, cur = cur->next) {
165 if (key->source_type == cur->key.source_type &&
166 key->target_type == cur->key.target_type &&
167 key->target_class == cur->key.target_class &&
168 (specified & cur->key.specified))
169 break;
170 if (key->source_type < cur->key.source_type)
171 break;
172 if (key->source_type == cur->key.source_type &&
173 key->target_type < cur->key.target_type)
174 break;
175 if (key->source_type == cur->key.source_type &&
176 key->target_type == cur->key.target_type &&
177 key->target_class < cur->key.target_class)
178 break;
179 }
180 return avtab_insert_node(h, hvalue, prev, key, datum);
181 }
182
183 /* This search function returns a node pointer, and can be used in
184 * conjunction with avtab_search_next_node()
185 */
avtab_search_node(struct avtab * h,const struct avtab_key * key)186 struct avtab_node *avtab_search_node(struct avtab *h,
187 const struct avtab_key *key)
188 {
189 u32 hvalue;
190 struct avtab_node *cur;
191 u16 specified = key->specified & ~(AVTAB_ENABLED|AVTAB_ENABLED_OLD);
192
193 if (!h || !h->nslot)
194 return NULL;
195
196 hvalue = avtab_hash(key, h->mask);
197 for (cur = h->htable[hvalue]; cur;
198 cur = cur->next) {
199 if (key->source_type == cur->key.source_type &&
200 key->target_type == cur->key.target_type &&
201 key->target_class == cur->key.target_class &&
202 (specified & cur->key.specified))
203 return cur;
204
205 if (key->source_type < cur->key.source_type)
206 break;
207 if (key->source_type == cur->key.source_type &&
208 key->target_type < cur->key.target_type)
209 break;
210 if (key->source_type == cur->key.source_type &&
211 key->target_type == cur->key.target_type &&
212 key->target_class < cur->key.target_class)
213 break;
214 }
215 return NULL;
216 }
217
218 struct avtab_node*
avtab_search_node_next(struct avtab_node * node,u16 specified)219 avtab_search_node_next(struct avtab_node *node, u16 specified)
220 {
221 struct avtab_node *cur;
222
223 if (!node)
224 return NULL;
225
226 specified &= ~(AVTAB_ENABLED|AVTAB_ENABLED_OLD);
227 for (cur = node->next; cur; cur = cur->next) {
228 if (node->key.source_type == cur->key.source_type &&
229 node->key.target_type == cur->key.target_type &&
230 node->key.target_class == cur->key.target_class &&
231 (specified & cur->key.specified))
232 return cur;
233
234 if (node->key.source_type < cur->key.source_type)
235 break;
236 if (node->key.source_type == cur->key.source_type &&
237 node->key.target_type < cur->key.target_type)
238 break;
239 if (node->key.source_type == cur->key.source_type &&
240 node->key.target_type == cur->key.target_type &&
241 node->key.target_class < cur->key.target_class)
242 break;
243 }
244 return NULL;
245 }
246
avtab_destroy(struct avtab * h)247 void avtab_destroy(struct avtab *h)
248 {
249 u32 i;
250 struct avtab_node *cur, *temp;
251
252 if (!h)
253 return;
254
255 for (i = 0; i < h->nslot; i++) {
256 cur = h->htable[i];
257 while (cur) {
258 temp = cur;
259 cur = cur->next;
260 if (temp->key.specified & AVTAB_XPERMS)
261 kmem_cache_free(avtab_xperms_cachep,
262 temp->datum.u.xperms);
263 kmem_cache_free(avtab_node_cachep, temp);
264 }
265 }
266 kvfree(h->htable);
267 h->htable = NULL;
268 h->nel = 0;
269 h->nslot = 0;
270 h->mask = 0;
271 }
272
avtab_init(struct avtab * h)273 void avtab_init(struct avtab *h)
274 {
275 h->htable = NULL;
276 h->nel = 0;
277 h->nslot = 0;
278 h->mask = 0;
279 }
280
avtab_alloc_common(struct avtab * h,u32 nslot)281 static int avtab_alloc_common(struct avtab *h, u32 nslot)
282 {
283 if (!nslot)
284 return 0;
285
286 h->htable = kvcalloc(nslot, sizeof(void *), GFP_KERNEL);
287 if (!h->htable)
288 return -ENOMEM;
289
290 h->nslot = nslot;
291 h->mask = nslot - 1;
292 return 0;
293 }
294
avtab_alloc(struct avtab * h,u32 nrules)295 int avtab_alloc(struct avtab *h, u32 nrules)
296 {
297 int rc;
298 u32 nslot = 0;
299
300 if (nrules != 0) {
301 u32 shift = 1;
302 u32 work = nrules >> 3;
303 while (work) {
304 work >>= 1;
305 shift++;
306 }
307 nslot = 1 << shift;
308 if (nslot > MAX_AVTAB_HASH_BUCKETS)
309 nslot = MAX_AVTAB_HASH_BUCKETS;
310
311 rc = avtab_alloc_common(h, nslot);
312 if (rc)
313 return rc;
314 }
315
316 pr_debug("SELinux: %d avtab hash slots, %d rules.\n", nslot, nrules);
317 return 0;
318 }
319
avtab_alloc_dup(struct avtab * new,const struct avtab * orig)320 int avtab_alloc_dup(struct avtab *new, const struct avtab *orig)
321 {
322 return avtab_alloc_common(new, orig->nslot);
323 }
324
325 #ifdef CONFIG_SECURITY_SELINUX_DEBUG
avtab_hash_eval(struct avtab * h,const char * tag)326 void avtab_hash_eval(struct avtab *h, const char *tag)
327 {
328 u32 i, chain_len, slots_used, max_chain_len;
329 unsigned long long chain2_len_sum;
330 struct avtab_node *cur;
331
332 slots_used = 0;
333 max_chain_len = 0;
334 chain2_len_sum = 0;
335 for (i = 0; i < h->nslot; i++) {
336 cur = h->htable[i];
337 if (cur) {
338 slots_used++;
339 chain_len = 0;
340 while (cur) {
341 chain_len++;
342 cur = cur->next;
343 }
344
345 if (chain_len > max_chain_len)
346 max_chain_len = chain_len;
347 chain2_len_sum += (unsigned long long)chain_len * chain_len;
348 }
349 }
350
351 pr_debug("SELinux: %s: %d entries and %d/%d buckets used, "
352 "longest chain length %d sum of chain length^2 %llu\n",
353 tag, h->nel, slots_used, h->nslot, max_chain_len,
354 chain2_len_sum);
355 }
356 #endif /* CONFIG_SECURITY_SELINUX_DEBUG */
357
358 static const uint16_t spec_order[] = {
359 AVTAB_ALLOWED,
360 AVTAB_AUDITDENY,
361 AVTAB_AUDITALLOW,
362 AVTAB_TRANSITION,
363 AVTAB_CHANGE,
364 AVTAB_MEMBER,
365 AVTAB_XPERMS_ALLOWED,
366 AVTAB_XPERMS_AUDITALLOW,
367 AVTAB_XPERMS_DONTAUDIT
368 };
369
avtab_read_item(struct avtab * a,void * fp,struct policydb * pol,int (* insertf)(struct avtab * a,const struct avtab_key * k,const struct avtab_datum * d,void * p),void * p)370 int avtab_read_item(struct avtab *a, void *fp, struct policydb *pol,
371 int (*insertf)(struct avtab *a, const struct avtab_key *k,
372 const struct avtab_datum *d, void *p),
373 void *p)
374 {
375 __le16 buf16[4];
376 u16 enabled;
377 u32 items, items2, val, i;
378 struct avtab_key key;
379 struct avtab_datum datum;
380 struct avtab_extended_perms xperms;
381 __le32 buf32[ARRAY_SIZE(xperms.perms.p)];
382 int rc;
383 unsigned int set, vers = pol->policyvers;
384
385 memset(&key, 0, sizeof(struct avtab_key));
386 memset(&datum, 0, sizeof(struct avtab_datum));
387
388 if (vers < POLICYDB_VERSION_AVTAB) {
389 rc = next_entry(buf32, fp, sizeof(u32));
390 if (rc) {
391 pr_err("SELinux: avtab: truncated entry\n");
392 return rc;
393 }
394 items2 = le32_to_cpu(buf32[0]);
395 if (items2 > ARRAY_SIZE(buf32)) {
396 pr_err("SELinux: avtab: entry overflow\n");
397 return -EINVAL;
398
399 }
400 rc = next_entry(buf32, fp, sizeof(u32)*items2);
401 if (rc) {
402 pr_err("SELinux: avtab: truncated entry\n");
403 return rc;
404 }
405 items = 0;
406
407 val = le32_to_cpu(buf32[items++]);
408 key.source_type = (u16)val;
409 if (key.source_type != val) {
410 pr_err("SELinux: avtab: truncated source type\n");
411 return -EINVAL;
412 }
413 val = le32_to_cpu(buf32[items++]);
414 key.target_type = (u16)val;
415 if (key.target_type != val) {
416 pr_err("SELinux: avtab: truncated target type\n");
417 return -EINVAL;
418 }
419 val = le32_to_cpu(buf32[items++]);
420 key.target_class = (u16)val;
421 if (key.target_class != val) {
422 pr_err("SELinux: avtab: truncated target class\n");
423 return -EINVAL;
424 }
425
426 val = le32_to_cpu(buf32[items++]);
427 enabled = (val & AVTAB_ENABLED_OLD) ? AVTAB_ENABLED : 0;
428
429 if (!(val & (AVTAB_AV | AVTAB_TYPE))) {
430 pr_err("SELinux: avtab: null entry\n");
431 return -EINVAL;
432 }
433 if ((val & AVTAB_AV) &&
434 (val & AVTAB_TYPE)) {
435 pr_err("SELinux: avtab: entry has both access vectors and types\n");
436 return -EINVAL;
437 }
438 if (val & AVTAB_XPERMS) {
439 pr_err("SELinux: avtab: entry has extended permissions\n");
440 return -EINVAL;
441 }
442
443 for (i = 0; i < ARRAY_SIZE(spec_order); i++) {
444 if (val & spec_order[i]) {
445 key.specified = spec_order[i] | enabled;
446 datum.u.data = le32_to_cpu(buf32[items++]);
447 rc = insertf(a, &key, &datum, p);
448 if (rc)
449 return rc;
450 }
451 }
452
453 if (items != items2) {
454 pr_err("SELinux: avtab: entry only had %d items, expected %d\n",
455 items2, items);
456 return -EINVAL;
457 }
458 return 0;
459 }
460
461 rc = next_entry(buf16, fp, sizeof(u16)*4);
462 if (rc) {
463 pr_err("SELinux: avtab: truncated entry\n");
464 return rc;
465 }
466
467 items = 0;
468 key.source_type = le16_to_cpu(buf16[items++]);
469 key.target_type = le16_to_cpu(buf16[items++]);
470 key.target_class = le16_to_cpu(buf16[items++]);
471 key.specified = le16_to_cpu(buf16[items++]);
472
473 if (!policydb_type_isvalid(pol, key.source_type) ||
474 !policydb_type_isvalid(pol, key.target_type) ||
475 !policydb_class_isvalid(pol, key.target_class)) {
476 pr_err("SELinux: avtab: invalid type or class\n");
477 return -EINVAL;
478 }
479
480 set = 0;
481 for (i = 0; i < ARRAY_SIZE(spec_order); i++) {
482 if (key.specified & spec_order[i])
483 set++;
484 }
485 if (!set || set > 1) {
486 pr_err("SELinux: avtab: more than one specifier\n");
487 return -EINVAL;
488 }
489
490 if ((vers < POLICYDB_VERSION_XPERMS_IOCTL) &&
491 (key.specified & AVTAB_XPERMS)) {
492 pr_err("SELinux: avtab: policy version %u does not "
493 "support extended permissions rules and one "
494 "was specified\n", vers);
495 return -EINVAL;
496 } else if (key.specified & AVTAB_XPERMS) {
497 memset(&xperms, 0, sizeof(struct avtab_extended_perms));
498 rc = next_entry(&xperms.specified, fp, sizeof(u8));
499 if (rc) {
500 pr_err("SELinux: avtab: truncated entry\n");
501 return rc;
502 }
503 rc = next_entry(&xperms.driver, fp, sizeof(u8));
504 if (rc) {
505 pr_err("SELinux: avtab: truncated entry\n");
506 return rc;
507 }
508 rc = next_entry(buf32, fp, sizeof(u32)*ARRAY_SIZE(xperms.perms.p));
509 if (rc) {
510 pr_err("SELinux: avtab: truncated entry\n");
511 return rc;
512 }
513 for (i = 0; i < ARRAY_SIZE(xperms.perms.p); i++)
514 xperms.perms.p[i] = le32_to_cpu(buf32[i]);
515 datum.u.xperms = &xperms;
516 } else {
517 rc = next_entry(buf32, fp, sizeof(u32));
518 if (rc) {
519 pr_err("SELinux: avtab: truncated entry\n");
520 return rc;
521 }
522 datum.u.data = le32_to_cpu(*buf32);
523 }
524 if ((key.specified & AVTAB_TYPE) &&
525 !policydb_type_isvalid(pol, datum.u.data)) {
526 pr_err("SELinux: avtab: invalid type\n");
527 return -EINVAL;
528 }
529 return insertf(a, &key, &datum, p);
530 }
531
avtab_insertf(struct avtab * a,const struct avtab_key * k,const struct avtab_datum * d,void * p)532 static int avtab_insertf(struct avtab *a, const struct avtab_key *k,
533 const struct avtab_datum *d, void *p)
534 {
535 return avtab_insert(a, k, d);
536 }
537
avtab_read(struct avtab * a,void * fp,struct policydb * pol)538 int avtab_read(struct avtab *a, void *fp, struct policydb *pol)
539 {
540 int rc;
541 __le32 buf[1];
542 u32 nel, i;
543
544
545 rc = next_entry(buf, fp, sizeof(u32));
546 if (rc < 0) {
547 pr_err("SELinux: avtab: truncated table\n");
548 goto bad;
549 }
550 nel = le32_to_cpu(buf[0]);
551 if (!nel) {
552 pr_err("SELinux: avtab: table is empty\n");
553 rc = -EINVAL;
554 goto bad;
555 }
556
557 rc = avtab_alloc(a, nel);
558 if (rc)
559 goto bad;
560
561 for (i = 0; i < nel; i++) {
562 rc = avtab_read_item(a, fp, pol, avtab_insertf, NULL);
563 if (rc) {
564 if (rc == -ENOMEM)
565 pr_err("SELinux: avtab: out of memory\n");
566 else if (rc == -EEXIST)
567 pr_err("SELinux: avtab: duplicate entry\n");
568
569 goto bad;
570 }
571 }
572
573 rc = 0;
574 out:
575 return rc;
576
577 bad:
578 avtab_destroy(a);
579 goto out;
580 }
581
avtab_write_item(struct policydb * p,const struct avtab_node * cur,void * fp)582 int avtab_write_item(struct policydb *p, const struct avtab_node *cur, void *fp)
583 {
584 __le16 buf16[4];
585 __le32 buf32[ARRAY_SIZE(cur->datum.u.xperms->perms.p)];
586 int rc;
587 unsigned int i;
588
589 buf16[0] = cpu_to_le16(cur->key.source_type);
590 buf16[1] = cpu_to_le16(cur->key.target_type);
591 buf16[2] = cpu_to_le16(cur->key.target_class);
592 buf16[3] = cpu_to_le16(cur->key.specified);
593 rc = put_entry(buf16, sizeof(u16), 4, fp);
594 if (rc)
595 return rc;
596
597 if (cur->key.specified & AVTAB_XPERMS) {
598 rc = put_entry(&cur->datum.u.xperms->specified, sizeof(u8), 1, fp);
599 if (rc)
600 return rc;
601 rc = put_entry(&cur->datum.u.xperms->driver, sizeof(u8), 1, fp);
602 if (rc)
603 return rc;
604 for (i = 0; i < ARRAY_SIZE(cur->datum.u.xperms->perms.p); i++)
605 buf32[i] = cpu_to_le32(cur->datum.u.xperms->perms.p[i]);
606 rc = put_entry(buf32, sizeof(u32),
607 ARRAY_SIZE(cur->datum.u.xperms->perms.p), fp);
608 } else {
609 buf32[0] = cpu_to_le32(cur->datum.u.data);
610 rc = put_entry(buf32, sizeof(u32), 1, fp);
611 }
612 if (rc)
613 return rc;
614 return 0;
615 }
616
avtab_write(struct policydb * p,struct avtab * a,void * fp)617 int avtab_write(struct policydb *p, struct avtab *a, void *fp)
618 {
619 u32 i;
620 int rc = 0;
621 struct avtab_node *cur;
622 __le32 buf[1];
623
624 buf[0] = cpu_to_le32(a->nel);
625 rc = put_entry(buf, sizeof(u32), 1, fp);
626 if (rc)
627 return rc;
628
629 for (i = 0; i < a->nslot; i++) {
630 for (cur = a->htable[i]; cur;
631 cur = cur->next) {
632 rc = avtab_write_item(p, cur, fp);
633 if (rc)
634 return rc;
635 }
636 }
637
638 return rc;
639 }
640
avtab_cache_init(void)641 void __init avtab_cache_init(void)
642 {
643 avtab_node_cachep = kmem_cache_create("avtab_node",
644 sizeof(struct avtab_node),
645 0, SLAB_PANIC, NULL);
646 avtab_xperms_cachep = kmem_cache_create("avtab_extended_perms",
647 sizeof(struct avtab_extended_perms),
648 0, SLAB_PANIC, NULL);
649 }
650