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 */ 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* 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 } 105 106 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 */ 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 */ 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* 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 } 246 247 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 } 272 273 void avtab_init(struct avtab *h) 274 { 275 h->htable = NULL; 276 h->nel = 0; 277 h->nslot = 0; 278 h->mask = 0; 279 } 280 281 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 } 294 295 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 } 319 320 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 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 }; 369 370 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 } 531 532 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 } 537 538 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 } 581 582 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 } 616 617 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 } 640 641 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