1 /*
2 * Implementation of the access vector table type.
3 *
4 * Author : Stephen Smalley, <sds@tycho.nsa.gov>
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;
27 static struct kmem_cache *avtab_xperms_cachep;
28
29 /* Based on MurmurHash3, written by Austin Appleby and placed in the
30 * public domain.
31 */
avtab_hash(struct avtab_key * keyp,u32 mask)32 static inline int avtab_hash(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) { \
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 }
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,int hvalue,struct avtab_node * prev,struct avtab_node * cur,struct avtab_key * key,struct avtab_datum * datum)69 avtab_insert_node(struct avtab *h, int hvalue,
70 struct avtab_node *prev, struct avtab_node *cur,
71 struct avtab_key *key, 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 newnode->next = flex_array_get_ptr(h->htable, hvalue);
97 if (flex_array_put_ptr(h->htable, hvalue, newnode,
98 GFP_KERNEL|__GFP_ZERO)) {
99 kmem_cache_free(avtab_node_cachep, newnode);
100 return NULL;
101 }
102 }
103
104 h->nel++;
105 return newnode;
106 }
107
avtab_insert(struct avtab * h,struct avtab_key * key,struct avtab_datum * datum)108 static int avtab_insert(struct avtab *h, struct avtab_key *key, struct avtab_datum *datum)
109 {
110 int hvalue;
111 struct avtab_node *prev, *cur, *newnode;
112 u16 specified = key->specified & ~(AVTAB_ENABLED|AVTAB_ENABLED_OLD);
113
114 if (!h || !h->htable)
115 return -EINVAL;
116
117 hvalue = avtab_hash(key, h->mask);
118 for (prev = NULL, cur = flex_array_get_ptr(h->htable, hvalue);
119 cur;
120 prev = cur, cur = cur->next) {
121 if (key->source_type == cur->key.source_type &&
122 key->target_type == cur->key.target_type &&
123 key->target_class == cur->key.target_class &&
124 (specified & cur->key.specified)) {
125 /* extended perms may not be unique */
126 if (specified & AVTAB_XPERMS)
127 break;
128 return -EEXIST;
129 }
130 if (key->source_type < cur->key.source_type)
131 break;
132 if (key->source_type == cur->key.source_type &&
133 key->target_type < cur->key.target_type)
134 break;
135 if (key->source_type == cur->key.source_type &&
136 key->target_type == cur->key.target_type &&
137 key->target_class < cur->key.target_class)
138 break;
139 }
140
141 newnode = avtab_insert_node(h, hvalue, prev, cur, key, datum);
142 if (!newnode)
143 return -ENOMEM;
144
145 return 0;
146 }
147
148 /* Unlike avtab_insert(), this function allow multiple insertions of the same
149 * key/specified mask into the table, as needed by the conditional avtab.
150 * It also returns a pointer to the node inserted.
151 */
152 struct avtab_node *
avtab_insert_nonunique(struct avtab * h,struct avtab_key * key,struct avtab_datum * datum)153 avtab_insert_nonunique(struct avtab *h, struct avtab_key *key, struct avtab_datum *datum)
154 {
155 int hvalue;
156 struct avtab_node *prev, *cur;
157 u16 specified = key->specified & ~(AVTAB_ENABLED|AVTAB_ENABLED_OLD);
158
159 if (!h || !h->htable)
160 return NULL;
161 hvalue = avtab_hash(key, h->mask);
162 for (prev = NULL, cur = flex_array_get_ptr(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, cur, key, datum);
181 }
182
avtab_search(struct avtab * h,struct avtab_key * key)183 struct avtab_datum *avtab_search(struct avtab *h, struct avtab_key *key)
184 {
185 int hvalue;
186 struct avtab_node *cur;
187 u16 specified = key->specified & ~(AVTAB_ENABLED|AVTAB_ENABLED_OLD);
188
189 if (!h || !h->htable)
190 return NULL;
191
192 hvalue = avtab_hash(key, h->mask);
193 for (cur = flex_array_get_ptr(h->htable, hvalue); cur;
194 cur = cur->next) {
195 if (key->source_type == cur->key.source_type &&
196 key->target_type == cur->key.target_type &&
197 key->target_class == cur->key.target_class &&
198 (specified & cur->key.specified))
199 return &cur->datum;
200
201 if (key->source_type < cur->key.source_type)
202 break;
203 if (key->source_type == cur->key.source_type &&
204 key->target_type < cur->key.target_type)
205 break;
206 if (key->source_type == cur->key.source_type &&
207 key->target_type == cur->key.target_type &&
208 key->target_class < cur->key.target_class)
209 break;
210 }
211
212 return NULL;
213 }
214
215 /* This search function returns a node pointer, and can be used in
216 * conjunction with avtab_search_next_node()
217 */
218 struct avtab_node*
avtab_search_node(struct avtab * h,struct avtab_key * key)219 avtab_search_node(struct avtab *h, struct avtab_key *key)
220 {
221 int hvalue;
222 struct avtab_node *cur;
223 u16 specified = key->specified & ~(AVTAB_ENABLED|AVTAB_ENABLED_OLD);
224
225 if (!h || !h->htable)
226 return NULL;
227
228 hvalue = avtab_hash(key, h->mask);
229 for (cur = flex_array_get_ptr(h->htable, hvalue); cur;
230 cur = cur->next) {
231 if (key->source_type == cur->key.source_type &&
232 key->target_type == cur->key.target_type &&
233 key->target_class == cur->key.target_class &&
234 (specified & cur->key.specified))
235 return cur;
236
237 if (key->source_type < cur->key.source_type)
238 break;
239 if (key->source_type == cur->key.source_type &&
240 key->target_type < cur->key.target_type)
241 break;
242 if (key->source_type == cur->key.source_type &&
243 key->target_type == cur->key.target_type &&
244 key->target_class < cur->key.target_class)
245 break;
246 }
247 return NULL;
248 }
249
250 struct avtab_node*
avtab_search_node_next(struct avtab_node * node,int specified)251 avtab_search_node_next(struct avtab_node *node, int specified)
252 {
253 struct avtab_node *cur;
254
255 if (!node)
256 return NULL;
257
258 specified &= ~(AVTAB_ENABLED|AVTAB_ENABLED_OLD);
259 for (cur = node->next; cur; cur = cur->next) {
260 if (node->key.source_type == cur->key.source_type &&
261 node->key.target_type == cur->key.target_type &&
262 node->key.target_class == cur->key.target_class &&
263 (specified & cur->key.specified))
264 return cur;
265
266 if (node->key.source_type < cur->key.source_type)
267 break;
268 if (node->key.source_type == cur->key.source_type &&
269 node->key.target_type < cur->key.target_type)
270 break;
271 if (node->key.source_type == cur->key.source_type &&
272 node->key.target_type == cur->key.target_type &&
273 node->key.target_class < cur->key.target_class)
274 break;
275 }
276 return NULL;
277 }
278
avtab_destroy(struct avtab * h)279 void avtab_destroy(struct avtab *h)
280 {
281 int i;
282 struct avtab_node *cur, *temp;
283
284 if (!h || !h->htable)
285 return;
286
287 for (i = 0; i < h->nslot; i++) {
288 cur = flex_array_get_ptr(h->htable, i);
289 while (cur) {
290 temp = cur;
291 cur = cur->next;
292 if (temp->key.specified & AVTAB_XPERMS)
293 kmem_cache_free(avtab_xperms_cachep,
294 temp->datum.u.xperms);
295 kmem_cache_free(avtab_node_cachep, temp);
296 }
297 }
298 flex_array_free(h->htable);
299 h->htable = NULL;
300 h->nslot = 0;
301 h->mask = 0;
302 }
303
avtab_init(struct avtab * h)304 int avtab_init(struct avtab *h)
305 {
306 h->htable = NULL;
307 h->nel = 0;
308 return 0;
309 }
310
avtab_alloc(struct avtab * h,u32 nrules)311 int avtab_alloc(struct avtab *h, u32 nrules)
312 {
313 u32 mask = 0;
314 u32 shift = 0;
315 u32 work = nrules;
316 u32 nslot = 0;
317
318 if (nrules == 0)
319 goto avtab_alloc_out;
320
321 while (work) {
322 work = work >> 1;
323 shift++;
324 }
325 if (shift > 2)
326 shift = shift - 2;
327 nslot = 1 << shift;
328 if (nslot > MAX_AVTAB_HASH_BUCKETS)
329 nslot = MAX_AVTAB_HASH_BUCKETS;
330 mask = nslot - 1;
331
332 h->htable = flex_array_alloc(sizeof(struct avtab_node *), nslot,
333 GFP_KERNEL | __GFP_ZERO);
334 if (!h->htable)
335 return -ENOMEM;
336
337 avtab_alloc_out:
338 h->nel = 0;
339 h->nslot = nslot;
340 h->mask = mask;
341 pr_debug("SELinux: %d avtab hash slots, %d rules.\n",
342 h->nslot, nrules);
343 return 0;
344 }
345
avtab_hash_eval(struct avtab * h,char * tag)346 void avtab_hash_eval(struct avtab *h, char *tag)
347 {
348 int i, chain_len, slots_used, max_chain_len;
349 unsigned long long chain2_len_sum;
350 struct avtab_node *cur;
351
352 slots_used = 0;
353 max_chain_len = 0;
354 chain2_len_sum = 0;
355 for (i = 0; i < h->nslot; i++) {
356 cur = flex_array_get_ptr(h->htable, i);
357 if (cur) {
358 slots_used++;
359 chain_len = 0;
360 while (cur) {
361 chain_len++;
362 cur = cur->next;
363 }
364
365 if (chain_len > max_chain_len)
366 max_chain_len = chain_len;
367 chain2_len_sum += chain_len * chain_len;
368 }
369 }
370
371 pr_debug("SELinux: %s: %d entries and %d/%d buckets used, "
372 "longest chain length %d sum of chain length^2 %llu\n",
373 tag, h->nel, slots_used, h->nslot, max_chain_len,
374 chain2_len_sum);
375 }
376
377 static uint16_t spec_order[] = {
378 AVTAB_ALLOWED,
379 AVTAB_AUDITDENY,
380 AVTAB_AUDITALLOW,
381 AVTAB_TRANSITION,
382 AVTAB_CHANGE,
383 AVTAB_MEMBER,
384 AVTAB_XPERMS_ALLOWED,
385 AVTAB_XPERMS_AUDITALLOW,
386 AVTAB_XPERMS_DONTAUDIT
387 };
388
avtab_read_item(struct avtab * a,void * fp,struct policydb * pol,int (* insertf)(struct avtab * a,struct avtab_key * k,struct avtab_datum * d,void * p),void * p)389 int avtab_read_item(struct avtab *a, void *fp, struct policydb *pol,
390 int (*insertf)(struct avtab *a, struct avtab_key *k,
391 struct avtab_datum *d, void *p),
392 void *p)
393 {
394 __le16 buf16[4];
395 u16 enabled;
396 u32 items, items2, val, vers = pol->policyvers;
397 struct avtab_key key;
398 struct avtab_datum datum;
399 struct avtab_extended_perms xperms;
400 __le32 buf32[ARRAY_SIZE(xperms.perms.p)];
401 int i, rc;
402 unsigned set;
403
404 memset(&key, 0, sizeof(struct avtab_key));
405 memset(&datum, 0, sizeof(struct avtab_datum));
406
407 if (vers < POLICYDB_VERSION_AVTAB) {
408 rc = next_entry(buf32, fp, sizeof(u32));
409 if (rc) {
410 pr_err("SELinux: avtab: truncated entry\n");
411 return rc;
412 }
413 items2 = le32_to_cpu(buf32[0]);
414 if (items2 > ARRAY_SIZE(buf32)) {
415 pr_err("SELinux: avtab: entry overflow\n");
416 return -EINVAL;
417
418 }
419 rc = next_entry(buf32, fp, sizeof(u32)*items2);
420 if (rc) {
421 pr_err("SELinux: avtab: truncated entry\n");
422 return rc;
423 }
424 items = 0;
425
426 val = le32_to_cpu(buf32[items++]);
427 key.source_type = (u16)val;
428 if (key.source_type != val) {
429 pr_err("SELinux: avtab: truncated source type\n");
430 return -EINVAL;
431 }
432 val = le32_to_cpu(buf32[items++]);
433 key.target_type = (u16)val;
434 if (key.target_type != val) {
435 pr_err("SELinux: avtab: truncated target type\n");
436 return -EINVAL;
437 }
438 val = le32_to_cpu(buf32[items++]);
439 key.target_class = (u16)val;
440 if (key.target_class != val) {
441 pr_err("SELinux: avtab: truncated target class\n");
442 return -EINVAL;
443 }
444
445 val = le32_to_cpu(buf32[items++]);
446 enabled = (val & AVTAB_ENABLED_OLD) ? AVTAB_ENABLED : 0;
447
448 if (!(val & (AVTAB_AV | AVTAB_TYPE))) {
449 pr_err("SELinux: avtab: null entry\n");
450 return -EINVAL;
451 }
452 if ((val & AVTAB_AV) &&
453 (val & AVTAB_TYPE)) {
454 pr_err("SELinux: avtab: entry has both access vectors and types\n");
455 return -EINVAL;
456 }
457 if (val & AVTAB_XPERMS) {
458 pr_err("SELinux: avtab: entry has extended permissions\n");
459 return -EINVAL;
460 }
461
462 for (i = 0; i < ARRAY_SIZE(spec_order); i++) {
463 if (val & spec_order[i]) {
464 key.specified = spec_order[i] | enabled;
465 datum.u.data = le32_to_cpu(buf32[items++]);
466 rc = insertf(a, &key, &datum, p);
467 if (rc)
468 return rc;
469 }
470 }
471
472 if (items != items2) {
473 pr_err("SELinux: avtab: entry only had %d items, expected %d\n",
474 items2, items);
475 return -EINVAL;
476 }
477 return 0;
478 }
479
480 rc = next_entry(buf16, fp, sizeof(u16)*4);
481 if (rc) {
482 pr_err("SELinux: avtab: truncated entry\n");
483 return rc;
484 }
485
486 items = 0;
487 key.source_type = le16_to_cpu(buf16[items++]);
488 key.target_type = le16_to_cpu(buf16[items++]);
489 key.target_class = le16_to_cpu(buf16[items++]);
490 key.specified = le16_to_cpu(buf16[items++]);
491
492 if (!policydb_type_isvalid(pol, key.source_type) ||
493 !policydb_type_isvalid(pol, key.target_type) ||
494 !policydb_class_isvalid(pol, key.target_class)) {
495 pr_err("SELinux: avtab: invalid type or class\n");
496 return -EINVAL;
497 }
498
499 set = 0;
500 for (i = 0; i < ARRAY_SIZE(spec_order); i++) {
501 if (key.specified & spec_order[i])
502 set++;
503 }
504 if (!set || set > 1) {
505 pr_err("SELinux: avtab: more than one specifier\n");
506 return -EINVAL;
507 }
508
509 if ((vers < POLICYDB_VERSION_XPERMS_IOCTL) &&
510 (key.specified & AVTAB_XPERMS)) {
511 pr_err("SELinux: avtab: policy version %u does not "
512 "support extended permissions rules and one "
513 "was specified\n", vers);
514 return -EINVAL;
515 } else if (key.specified & AVTAB_XPERMS) {
516 memset(&xperms, 0, sizeof(struct avtab_extended_perms));
517 rc = next_entry(&xperms.specified, fp, sizeof(u8));
518 if (rc) {
519 pr_err("SELinux: avtab: truncated entry\n");
520 return rc;
521 }
522 rc = next_entry(&xperms.driver, fp, sizeof(u8));
523 if (rc) {
524 pr_err("SELinux: avtab: truncated entry\n");
525 return rc;
526 }
527 rc = next_entry(buf32, fp, sizeof(u32)*ARRAY_SIZE(xperms.perms.p));
528 if (rc) {
529 pr_err("SELinux: avtab: truncated entry\n");
530 return rc;
531 }
532 for (i = 0; i < ARRAY_SIZE(xperms.perms.p); i++)
533 xperms.perms.p[i] = le32_to_cpu(buf32[i]);
534 datum.u.xperms = &xperms;
535 } else {
536 rc = next_entry(buf32, fp, sizeof(u32));
537 if (rc) {
538 pr_err("SELinux: avtab: truncated entry\n");
539 return rc;
540 }
541 datum.u.data = le32_to_cpu(*buf32);
542 }
543 if ((key.specified & AVTAB_TYPE) &&
544 !policydb_type_isvalid(pol, datum.u.data)) {
545 pr_err("SELinux: avtab: invalid type\n");
546 return -EINVAL;
547 }
548 return insertf(a, &key, &datum, p);
549 }
550
avtab_insertf(struct avtab * a,struct avtab_key * k,struct avtab_datum * d,void * p)551 static int avtab_insertf(struct avtab *a, struct avtab_key *k,
552 struct avtab_datum *d, void *p)
553 {
554 return avtab_insert(a, k, d);
555 }
556
avtab_read(struct avtab * a,void * fp,struct policydb * pol)557 int avtab_read(struct avtab *a, void *fp, struct policydb *pol)
558 {
559 int rc;
560 __le32 buf[1];
561 u32 nel, i;
562
563
564 rc = next_entry(buf, fp, sizeof(u32));
565 if (rc < 0) {
566 pr_err("SELinux: avtab: truncated table\n");
567 goto bad;
568 }
569 nel = le32_to_cpu(buf[0]);
570 if (!nel) {
571 pr_err("SELinux: avtab: table is empty\n");
572 rc = -EINVAL;
573 goto bad;
574 }
575
576 rc = avtab_alloc(a, nel);
577 if (rc)
578 goto bad;
579
580 for (i = 0; i < nel; i++) {
581 rc = avtab_read_item(a, fp, pol, avtab_insertf, NULL);
582 if (rc) {
583 if (rc == -ENOMEM)
584 pr_err("SELinux: avtab: out of memory\n");
585 else if (rc == -EEXIST)
586 pr_err("SELinux: avtab: duplicate entry\n");
587
588 goto bad;
589 }
590 }
591
592 rc = 0;
593 out:
594 return rc;
595
596 bad:
597 avtab_destroy(a);
598 goto out;
599 }
600
avtab_write_item(struct policydb * p,struct avtab_node * cur,void * fp)601 int avtab_write_item(struct policydb *p, struct avtab_node *cur, void *fp)
602 {
603 __le16 buf16[4];
604 __le32 buf32[ARRAY_SIZE(cur->datum.u.xperms->perms.p)];
605 int rc;
606 unsigned int i;
607
608 buf16[0] = cpu_to_le16(cur->key.source_type);
609 buf16[1] = cpu_to_le16(cur->key.target_type);
610 buf16[2] = cpu_to_le16(cur->key.target_class);
611 buf16[3] = cpu_to_le16(cur->key.specified);
612 rc = put_entry(buf16, sizeof(u16), 4, fp);
613 if (rc)
614 return rc;
615
616 if (cur->key.specified & AVTAB_XPERMS) {
617 rc = put_entry(&cur->datum.u.xperms->specified, sizeof(u8), 1, fp);
618 if (rc)
619 return rc;
620 rc = put_entry(&cur->datum.u.xperms->driver, sizeof(u8), 1, fp);
621 if (rc)
622 return rc;
623 for (i = 0; i < ARRAY_SIZE(cur->datum.u.xperms->perms.p); i++)
624 buf32[i] = cpu_to_le32(cur->datum.u.xperms->perms.p[i]);
625 rc = put_entry(buf32, sizeof(u32),
626 ARRAY_SIZE(cur->datum.u.xperms->perms.p), fp);
627 } else {
628 buf32[0] = cpu_to_le32(cur->datum.u.data);
629 rc = put_entry(buf32, sizeof(u32), 1, fp);
630 }
631 if (rc)
632 return rc;
633 return 0;
634 }
635
avtab_write(struct policydb * p,struct avtab * a,void * fp)636 int avtab_write(struct policydb *p, struct avtab *a, void *fp)
637 {
638 unsigned int i;
639 int rc = 0;
640 struct avtab_node *cur;
641 __le32 buf[1];
642
643 buf[0] = cpu_to_le32(a->nel);
644 rc = put_entry(buf, sizeof(u32), 1, fp);
645 if (rc)
646 return rc;
647
648 for (i = 0; i < a->nslot; i++) {
649 for (cur = flex_array_get_ptr(a->htable, i); cur;
650 cur = cur->next) {
651 rc = avtab_write_item(p, cur, fp);
652 if (rc)
653 return rc;
654 }
655 }
656
657 return rc;
658 }
659
avtab_cache_init(void)660 void __init avtab_cache_init(void)
661 {
662 avtab_node_cachep = kmem_cache_create("avtab_node",
663 sizeof(struct avtab_node),
664 0, SLAB_PANIC, NULL);
665 avtab_xperms_cachep = kmem_cache_create("avtab_extended_perms",
666 sizeof(struct avtab_extended_perms),
667 0, SLAB_PANIC, NULL);
668 }
669
