1 /* SPDX-License-Identifier: GPL-2.0-only */ 2 /* Authors: Karl MacMillan <kmacmillan@tresys.com> 3 * Frank Mayer <mayerf@tresys.com> 4 * Copyright (C) 2003 - 2004 Tresys Technology, LLC 5 */ 6 7 #include <linux/kernel.h> 8 #include <linux/errno.h> 9 #include <linux/string.h> 10 #include <linux/spinlock.h> 11 #include <linux/slab.h> 12 13 #include "security.h" 14 #include "conditional.h" 15 #include "policydb.h" 16 #include "services.h" 17 18 /* 19 * cond_evaluate_expr evaluates a conditional expr 20 * in reverse polish notation. It returns true (1), false (0), 21 * or undefined (-1). Undefined occurs when the expression 22 * exceeds the stack depth of COND_EXPR_MAXDEPTH. 23 */ 24 static int cond_evaluate_expr(struct policydb *p, struct cond_expr *expr) 25 { 26 u32 i; 27 int s[COND_EXPR_MAXDEPTH]; 28 int sp = -1; 29 30 if (expr->len == 0) 31 return -1; 32 33 for (i = 0; i < expr->len; i++) { 34 struct cond_expr_node *node = &expr->nodes[i]; 35 36 switch (node->expr_type) { 37 case COND_BOOL: 38 if (sp == (COND_EXPR_MAXDEPTH - 1)) 39 return -1; 40 sp++; 41 s[sp] = p->bool_val_to_struct[node->boolean - 1]->state; 42 break; 43 case COND_NOT: 44 if (sp < 0) 45 return -1; 46 s[sp] = !s[sp]; 47 break; 48 case COND_OR: 49 if (sp < 1) 50 return -1; 51 sp--; 52 s[sp] |= s[sp + 1]; 53 break; 54 case COND_AND: 55 if (sp < 1) 56 return -1; 57 sp--; 58 s[sp] &= s[sp + 1]; 59 break; 60 case COND_XOR: 61 if (sp < 1) 62 return -1; 63 sp--; 64 s[sp] ^= s[sp + 1]; 65 break; 66 case COND_EQ: 67 if (sp < 1) 68 return -1; 69 sp--; 70 s[sp] = (s[sp] == s[sp + 1]); 71 break; 72 case COND_NEQ: 73 if (sp < 1) 74 return -1; 75 sp--; 76 s[sp] = (s[sp] != s[sp + 1]); 77 break; 78 default: 79 return -1; 80 } 81 } 82 return s[0]; 83 } 84 85 /* 86 * evaluate_cond_node evaluates the conditional stored in 87 * a struct cond_node and if the result is different than the 88 * current state of the node it sets the rules in the true/false 89 * list appropriately. If the result of the expression is undefined 90 * all of the rules are disabled for safety. 91 */ 92 static void evaluate_cond_node(struct policydb *p, struct cond_node *node) 93 { 94 struct avtab_node *avnode; 95 int new_state; 96 u32 i; 97 98 new_state = cond_evaluate_expr(p, &node->expr); 99 if (new_state != node->cur_state) { 100 node->cur_state = new_state; 101 if (new_state == -1) 102 pr_err("SELinux: expression result was undefined - disabling all rules.\n"); 103 /* turn the rules on or off */ 104 for (i = 0; i < node->true_list.len; i++) { 105 avnode = node->true_list.nodes[i]; 106 if (new_state <= 0) 107 avnode->key.specified &= ~AVTAB_ENABLED; 108 else 109 avnode->key.specified |= AVTAB_ENABLED; 110 } 111 112 for (i = 0; i < node->false_list.len; i++) { 113 avnode = node->false_list.nodes[i]; 114 /* -1 or 1 */ 115 if (new_state) 116 avnode->key.specified &= ~AVTAB_ENABLED; 117 else 118 avnode->key.specified |= AVTAB_ENABLED; 119 } 120 } 121 } 122 123 void evaluate_cond_nodes(struct policydb *p) 124 { 125 u32 i; 126 127 for (i = 0; i < p->cond_list_len; i++) 128 evaluate_cond_node(p, &p->cond_list[i]); 129 } 130 131 void cond_policydb_init(struct policydb *p) 132 { 133 p->bool_val_to_struct = NULL; 134 p->cond_list = NULL; 135 p->cond_list_len = 0; 136 137 avtab_init(&p->te_cond_avtab); 138 } 139 140 static void cond_node_destroy(struct cond_node *node) 141 { 142 kfree(node->expr.nodes); 143 /* the avtab_ptr_t nodes are destroyed by the avtab */ 144 kfree(node->true_list.nodes); 145 kfree(node->false_list.nodes); 146 } 147 148 static void cond_list_destroy(struct policydb *p) 149 { 150 u32 i; 151 152 for (i = 0; i < p->cond_list_len; i++) 153 cond_node_destroy(&p->cond_list[i]); 154 kfree(p->cond_list); 155 p->cond_list = NULL; 156 p->cond_list_len = 0; 157 } 158 159 void cond_policydb_destroy(struct policydb *p) 160 { 161 kfree(p->bool_val_to_struct); 162 avtab_destroy(&p->te_cond_avtab); 163 cond_list_destroy(p); 164 } 165 166 int cond_init_bool_indexes(struct policydb *p) 167 { 168 kfree(p->bool_val_to_struct); 169 p->bool_val_to_struct = kzalloc_objs(*p->bool_val_to_struct, 170 p->p_bools.nprim); 171 if (!p->bool_val_to_struct) 172 return -ENOMEM; 173 174 avtab_hash_eval(&p->te_cond_avtab, "conditional_rules"); 175 176 return 0; 177 } 178 179 int cond_destroy_bool(void *key, void *datum, void *p) 180 { 181 kfree(key); 182 kfree(datum); 183 return 0; 184 } 185 186 int cond_index_bool(void *key, void *datum, void *datap) 187 { 188 struct policydb *p; 189 struct cond_bool_datum *booldatum; 190 191 booldatum = datum; 192 p = datap; 193 194 if (!booldatum->value || booldatum->value > p->p_bools.nprim) 195 return -EINVAL; 196 197 p->sym_val_to_name[SYM_BOOLS][booldatum->value - 1] = key; 198 p->bool_val_to_struct[booldatum->value - 1] = booldatum; 199 200 return 0; 201 } 202 203 int cond_read_bool(struct policydb *p, struct symtab *s, struct policy_file *fp) 204 { 205 char *key = NULL; 206 struct cond_bool_datum *booldatum; 207 __le32 buf[3]; 208 u32 len, val; 209 int rc; 210 211 booldatum = kzalloc_obj(*booldatum); 212 if (!booldatum) 213 return -ENOMEM; 214 215 rc = next_entry(buf, fp, sizeof(buf)); 216 if (rc) 217 goto err; 218 219 booldatum->value = le32_to_cpu(buf[0]); 220 val = le32_to_cpu(buf[1]); 221 222 rc = -EINVAL; 223 if (!val_is_boolean(val)) 224 goto err; 225 booldatum->state = (int)val; 226 227 len = le32_to_cpu(buf[2]); 228 229 rc = str_read(&key, GFP_KERNEL, fp, len); 230 if (rc) 231 goto err; 232 233 rc = symtab_insert(s, key, booldatum); 234 if (rc) 235 goto err; 236 237 return 0; 238 err: 239 pr_err("SELinux: conditional: failed to read boolean\n"); 240 cond_destroy_bool(key, booldatum, NULL); 241 return rc; 242 } 243 244 struct cond_insertf_data { 245 struct policydb *p; 246 struct avtab_node **dst; 247 struct cond_av_list *other; 248 }; 249 250 static int cond_insertf(struct avtab *a, const struct avtab_key *k, 251 const struct avtab_datum *d, void *ptr) 252 { 253 struct cond_insertf_data *data = ptr; 254 struct policydb *p = data->p; 255 struct cond_av_list *other = data->other; 256 struct avtab_node *node_ptr; 257 u32 i; 258 bool found; 259 260 /* 261 * For type rules we have to make certain there aren't any 262 * conflicting rules by searching the te_avtab and the 263 * cond_te_avtab. 264 */ 265 if (k->specified & AVTAB_TYPE) { 266 if (avtab_search_node(&p->te_avtab, k)) { 267 pr_err("SELinux: type rule already exists outside of a conditional.\n"); 268 return -EINVAL; 269 } 270 /* 271 * If we are reading the false list other will be a pointer to 272 * the true list. We can have duplicate entries if there is only 273 * 1 other entry and it is in our true list. 274 * 275 * If we are reading the true list (other == NULL) there shouldn't 276 * be any other entries. 277 */ 278 if (other) { 279 node_ptr = avtab_search_node(&p->te_cond_avtab, k); 280 if (node_ptr) { 281 if (avtab_search_node_next(node_ptr, 282 k->specified)) { 283 pr_err("SELinux: too many conflicting type rules.\n"); 284 return -EINVAL; 285 } 286 found = false; 287 for (i = 0; i < other->len; i++) { 288 if (other->nodes[i] == node_ptr) { 289 found = true; 290 break; 291 } 292 } 293 if (!found) { 294 pr_err("SELinux: conflicting type rules.\n"); 295 return -EINVAL; 296 } 297 } 298 } else { 299 if (avtab_search_node(&p->te_cond_avtab, k)) { 300 pr_err("SELinux: conflicting type rules when adding type rule for true.\n"); 301 return -EINVAL; 302 } 303 } 304 } 305 306 node_ptr = avtab_insert_nonunique(&p->te_cond_avtab, k, d); 307 if (!node_ptr) { 308 pr_err("SELinux: could not insert rule.\n"); 309 return -ENOMEM; 310 } 311 312 *data->dst = node_ptr; 313 return 0; 314 } 315 316 static int cond_read_av_list(struct policydb *p, struct policy_file *fp, 317 struct cond_av_list *list, 318 struct cond_av_list *other) 319 { 320 int rc; 321 __le32 buf[1]; 322 u32 i, len; 323 struct cond_insertf_data data; 324 325 rc = next_entry(buf, fp, sizeof(u32)); 326 if (rc) 327 return rc; 328 329 len = le32_to_cpu(buf[0]); 330 if (len == 0) 331 return 0; 332 333 /* avtab_read_item() reads at least 96 bytes for any valid entry */ 334 rc = size_check(3 * sizeof(u32), len, fp); 335 if (rc) 336 return rc; 337 338 list->nodes = kzalloc_objs(*list->nodes, len); 339 if (!list->nodes) 340 return -ENOMEM; 341 342 data.p = p; 343 data.other = other; 344 for (i = 0; i < len; i++) { 345 data.dst = &list->nodes[i]; 346 rc = avtab_read_item(&p->te_cond_avtab, fp, p, cond_insertf, 347 &data, true); 348 if (rc) { 349 kfree(list->nodes); 350 list->nodes = NULL; 351 return rc; 352 } 353 } 354 355 list->len = len; 356 return 0; 357 } 358 359 static int expr_node_isvalid(struct policydb *p, struct cond_expr_node *expr) 360 { 361 if (expr->expr_type <= 0 || expr->expr_type > COND_LAST) { 362 pr_err("SELinux: conditional expressions uses unknown operator.\n"); 363 return 0; 364 } 365 366 if (expr->expr_type == COND_BOOL && 367 (expr->boolean == 0 || expr->boolean > p->p_bools.nprim)) { 368 pr_err("SELinux: conditional expressions uses unknown bool.\n"); 369 return 0; 370 } 371 return 1; 372 } 373 374 static int cond_read_node(struct policydb *p, struct cond_node *node, struct policy_file *fp) 375 { 376 __le32 buf[2]; 377 u32 i, len; 378 int rc; 379 380 rc = next_entry(buf, fp, sizeof(u32) * 2); 381 if (rc) 382 return rc; 383 384 node->cur_state = le32_to_cpu(buf[0]); 385 386 /* expr */ 387 len = le32_to_cpu(buf[1]); 388 389 /* we will read 64 bytes per node */ 390 rc = size_check(2 * sizeof(u32), len, fp); 391 if (rc) 392 return rc; 393 394 node->expr.nodes = kzalloc_objs(*node->expr.nodes, len); 395 if (!node->expr.nodes) 396 return -ENOMEM; 397 398 node->expr.len = len; 399 400 for (i = 0; i < len; i++) { 401 struct cond_expr_node *expr = &node->expr.nodes[i]; 402 403 rc = next_entry(buf, fp, sizeof(u32) * 2); 404 if (rc) 405 return rc; 406 407 expr->expr_type = le32_to_cpu(buf[0]); 408 expr->boolean = le32_to_cpu(buf[1]); 409 410 if (!expr_node_isvalid(p, expr)) 411 return -EINVAL; 412 } 413 414 rc = cond_read_av_list(p, fp, &node->true_list, NULL); 415 if (rc) 416 return rc; 417 return cond_read_av_list(p, fp, &node->false_list, &node->true_list); 418 } 419 420 int cond_read_list(struct policydb *p, struct policy_file *fp) 421 { 422 __le32 buf[1]; 423 u32 i, len; 424 int rc; 425 426 rc = next_entry(buf, fp, sizeof(buf)); 427 if (rc) 428 return rc; 429 430 len = le32_to_cpu(buf[0]); 431 432 /* cond_read_node() reads at least 128 bytes for any valid node */ 433 rc = size_check(4 * sizeof(u32), len, fp); 434 if (rc) 435 return rc; 436 437 p->cond_list = kzalloc_objs(*p->cond_list, len); 438 if (!p->cond_list) 439 return -ENOMEM; 440 441 rc = avtab_alloc(&(p->te_cond_avtab), p->te_avtab.nel); 442 if (rc) 443 goto err; 444 445 p->cond_list_len = len; 446 447 for (i = 0; i < len; i++) { 448 rc = cond_read_node(p, &p->cond_list[i], fp); 449 if (rc) 450 goto err; 451 } 452 return 0; 453 err: 454 cond_list_destroy(p); 455 return rc; 456 } 457 458 int cond_write_bool(void *vkey, void *datum, void *ptr) 459 { 460 char *key = vkey; 461 struct cond_bool_datum *booldatum = datum; 462 struct policy_data *pd = ptr; 463 struct policy_file *fp = pd->fp; 464 __le32 buf[3]; 465 u32 len; 466 int rc; 467 468 len = strlen(key); 469 buf[0] = cpu_to_le32(booldatum->value); 470 buf[1] = cpu_to_le32(booldatum->state); 471 buf[2] = cpu_to_le32(len); 472 rc = put_entry(buf, sizeof(u32), 3, fp); 473 if (rc) 474 return rc; 475 rc = put_entry(key, 1, len, fp); 476 if (rc) 477 return rc; 478 return 0; 479 } 480 481 /* 482 * cond_write_cond_av_list doesn't write out the av_list nodes. 483 * Instead it writes out the key/value pairs from the avtab. This 484 * is necessary because there is no way to uniquely identifying rules 485 * in the avtab so it is not possible to associate individual rules 486 * in the avtab with a conditional without saving them as part of 487 * the conditional. This means that the avtab with the conditional 488 * rules will not be saved but will be rebuilt on policy load. 489 */ 490 static int cond_write_av_list(struct policydb *p, struct cond_av_list *list, 491 struct policy_file *fp) 492 { 493 __le32 buf[1]; 494 u32 i; 495 int rc; 496 497 buf[0] = cpu_to_le32(list->len); 498 rc = put_entry(buf, sizeof(u32), 1, fp); 499 if (rc) 500 return rc; 501 502 for (i = 0; i < list->len; i++) { 503 rc = avtab_write_item(p, list->nodes[i], fp); 504 if (rc) 505 return rc; 506 } 507 508 return 0; 509 } 510 511 static int cond_write_node(struct policydb *p, struct cond_node *node, 512 struct policy_file *fp) 513 { 514 __le32 buf[2]; 515 int rc; 516 u32 i; 517 518 buf[0] = cpu_to_le32(node->cur_state); 519 rc = put_entry(buf, sizeof(u32), 1, fp); 520 if (rc) 521 return rc; 522 523 buf[0] = cpu_to_le32(node->expr.len); 524 rc = put_entry(buf, sizeof(u32), 1, fp); 525 if (rc) 526 return rc; 527 528 for (i = 0; i < node->expr.len; i++) { 529 buf[0] = cpu_to_le32(node->expr.nodes[i].expr_type); 530 buf[1] = cpu_to_le32(node->expr.nodes[i].boolean); 531 rc = put_entry(buf, sizeof(u32), 2, fp); 532 if (rc) 533 return rc; 534 } 535 536 rc = cond_write_av_list(p, &node->true_list, fp); 537 if (rc) 538 return rc; 539 rc = cond_write_av_list(p, &node->false_list, fp); 540 if (rc) 541 return rc; 542 543 return 0; 544 } 545 546 int cond_write_list(struct policydb *p, struct policy_file *fp) 547 { 548 u32 i; 549 __le32 buf[1]; 550 int rc; 551 552 buf[0] = cpu_to_le32(p->cond_list_len); 553 rc = put_entry(buf, sizeof(u32), 1, fp); 554 if (rc) 555 return rc; 556 557 for (i = 0; i < p->cond_list_len; i++) { 558 rc = cond_write_node(p, &p->cond_list[i], fp); 559 if (rc) 560 return rc; 561 } 562 563 return 0; 564 } 565 566 void cond_compute_xperms(struct avtab *ctab, struct avtab_key *key, 567 struct extended_perms_decision *xpermd) 568 { 569 struct avtab_node *node; 570 571 if (!ctab || !key || !xpermd) 572 return; 573 574 for (node = avtab_search_node(ctab, key); node; 575 node = avtab_search_node_next(node, key->specified)) { 576 if (node->key.specified & AVTAB_ENABLED) 577 services_compute_xperms_decision(xpermd, node); 578 } 579 } 580 /* Determine whether additional permissions are granted by the conditional 581 * av table, and if so, add them to the result 582 */ 583 void cond_compute_av(struct avtab *ctab, struct avtab_key *key, 584 struct av_decision *avd, struct extended_perms *xperms) 585 { 586 struct avtab_node *node; 587 588 if (!ctab || !key || !avd) 589 return; 590 591 for (node = avtab_search_node(ctab, key); node; 592 node = avtab_search_node_next(node, key->specified)) { 593 if ((u16)(AVTAB_ALLOWED | AVTAB_ENABLED) == 594 (node->key.specified & (AVTAB_ALLOWED | AVTAB_ENABLED))) 595 avd->allowed |= node->datum.u.data; 596 if ((u16)(AVTAB_AUDITDENY | AVTAB_ENABLED) == 597 (node->key.specified & (AVTAB_AUDITDENY | AVTAB_ENABLED))) 598 /* Since a '0' in an auditdeny mask represents a 599 * permission we do NOT want to audit (dontaudit), we use 600 * the '&' operand to ensure that all '0's in the mask 601 * are retained (much unlike the allow and auditallow cases). 602 */ 603 avd->auditdeny &= node->datum.u.data; 604 if ((u16)(AVTAB_AUDITALLOW | AVTAB_ENABLED) == 605 (node->key.specified & (AVTAB_AUDITALLOW | AVTAB_ENABLED))) 606 avd->auditallow |= node->datum.u.data; 607 if (xperms && (node->key.specified & AVTAB_ENABLED) && 608 (node->key.specified & AVTAB_XPERMS)) 609 services_compute_xperms_drivers(xperms, node); 610 } 611 } 612 613 static int cond_dup_av_list(struct cond_av_list *new, 614 const struct cond_av_list *orig, 615 struct avtab *avtab) 616 { 617 u32 i; 618 619 memset(new, 0, sizeof(*new)); 620 621 new->nodes = kzalloc_objs(*new->nodes, orig->len); 622 if (!new->nodes) 623 return -ENOMEM; 624 625 for (i = 0; i < orig->len; i++) { 626 new->nodes[i] = avtab_insert_nonunique( 627 avtab, &orig->nodes[i]->key, &orig->nodes[i]->datum); 628 if (!new->nodes[i]) 629 return -ENOMEM; 630 new->len++; 631 } 632 633 return 0; 634 } 635 636 static int duplicate_policydb_cond_list(struct policydb *newp, 637 const struct policydb *origp) 638 { 639 int rc; 640 u32 i; 641 642 rc = avtab_alloc_dup(&newp->te_cond_avtab, &origp->te_cond_avtab); 643 if (rc) 644 return rc; 645 646 newp->cond_list_len = 0; 647 newp->cond_list = kzalloc_objs(*newp->cond_list, origp->cond_list_len); 648 if (!newp->cond_list) 649 goto error; 650 651 for (i = 0; i < origp->cond_list_len; i++) { 652 struct cond_node *newn = &newp->cond_list[i]; 653 const struct cond_node *orign = &origp->cond_list[i]; 654 655 newp->cond_list_len++; 656 657 newn->cur_state = orign->cur_state; 658 newn->expr.nodes = 659 kmemdup(orign->expr.nodes, 660 orign->expr.len * sizeof(*orign->expr.nodes), 661 GFP_KERNEL); 662 if (!newn->expr.nodes) 663 goto error; 664 665 newn->expr.len = orign->expr.len; 666 667 rc = cond_dup_av_list(&newn->true_list, &orign->true_list, 668 &newp->te_cond_avtab); 669 if (rc) 670 goto error; 671 672 rc = cond_dup_av_list(&newn->false_list, &orign->false_list, 673 &newp->te_cond_avtab); 674 if (rc) 675 goto error; 676 } 677 678 return 0; 679 680 error: 681 avtab_destroy(&newp->te_cond_avtab); 682 cond_list_destroy(newp); 683 return -ENOMEM; 684 } 685 686 static int cond_bools_destroy(void *key, void *datum, void *args) 687 { 688 /* key was not copied so no need to free here */ 689 kfree(datum); 690 return 0; 691 } 692 693 static int cond_bools_copy(struct hashtab_node *new, 694 const struct hashtab_node *orig, void *args) 695 { 696 struct cond_bool_datum *datum; 697 698 datum = kmemdup(orig->datum, sizeof(struct cond_bool_datum), 699 GFP_KERNEL); 700 if (!datum) 701 return -ENOMEM; 702 703 new->key = orig->key; /* No need to copy, never modified */ 704 new->datum = datum; 705 return 0; 706 } 707 708 static int cond_bools_index(void *key, void *datum, void *args) 709 { 710 struct cond_bool_datum *booldatum, **cond_bool_array; 711 712 booldatum = datum; 713 cond_bool_array = args; 714 cond_bool_array[booldatum->value - 1] = booldatum; 715 716 return 0; 717 } 718 719 static int duplicate_policydb_bools(struct policydb *newdb, 720 const struct policydb *orig) 721 { 722 struct cond_bool_datum **cond_bool_array; 723 int rc; 724 725 cond_bool_array = kzalloc_objs(*orig->bool_val_to_struct, 726 orig->p_bools.nprim); 727 if (!cond_bool_array) 728 return -ENOMEM; 729 730 rc = hashtab_duplicate(&newdb->p_bools.table, &orig->p_bools.table, 731 cond_bools_copy, cond_bools_destroy, NULL); 732 if (rc) { 733 kfree(cond_bool_array); 734 return -ENOMEM; 735 } 736 737 hashtab_map(&newdb->p_bools.table, cond_bools_index, cond_bool_array); 738 newdb->bool_val_to_struct = cond_bool_array; 739 740 newdb->p_bools.nprim = orig->p_bools.nprim; 741 742 return 0; 743 } 744 745 void cond_policydb_destroy_dup(struct policydb *p) 746 { 747 hashtab_map(&p->p_bools.table, cond_bools_destroy, NULL); 748 hashtab_destroy(&p->p_bools.table); 749 cond_policydb_destroy(p); 750 } 751 752 int cond_policydb_dup(struct policydb *new, const struct policydb *orig) 753 { 754 cond_policydb_init(new); 755 756 if (duplicate_policydb_bools(new, orig)) 757 return -ENOMEM; 758 759 if (duplicate_policydb_cond_list(new, orig)) { 760 cond_policydb_destroy_dup(new); 761 return -ENOMEM; 762 } 763 764 return 0; 765 } 766