1 // SPDX-License-Identifier: GPL-2.0-only 2 /* Authors: Karl MacMillan <kmacmillan@tresys.com> 3 * Frank Mayer <mayerf@tresys.com> 4 * 5 * Copyright (C) 2003 - 2004 Tresys Technology, LLC 6 */ 7 8 #include <linux/kernel.h> 9 #include <linux/errno.h> 10 #include <linux/string.h> 11 #include <linux/spinlock.h> 12 #include <linux/slab.h> 13 14 #include "security.h" 15 #include "conditional.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->bool - 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 } 156 157 void cond_policydb_destroy(struct policydb *p) 158 { 159 kfree(p->bool_val_to_struct); 160 avtab_destroy(&p->te_cond_avtab); 161 cond_list_destroy(p); 162 } 163 164 int cond_init_bool_indexes(struct policydb *p) 165 { 166 kfree(p->bool_val_to_struct); 167 p->bool_val_to_struct = kmalloc_array(p->p_bools.nprim, 168 sizeof(*p->bool_val_to_struct), 169 GFP_KERNEL); 170 if (!p->bool_val_to_struct) 171 return -ENOMEM; 172 return 0; 173 } 174 175 int cond_destroy_bool(void *key, void *datum, void *p) 176 { 177 kfree(key); 178 kfree(datum); 179 return 0; 180 } 181 182 int cond_index_bool(void *key, void *datum, void *datap) 183 { 184 struct policydb *p; 185 struct cond_bool_datum *booldatum; 186 187 booldatum = datum; 188 p = datap; 189 190 if (!booldatum->value || booldatum->value > p->p_bools.nprim) 191 return -EINVAL; 192 193 p->sym_val_to_name[SYM_BOOLS][booldatum->value - 1] = key; 194 p->bool_val_to_struct[booldatum->value - 1] = booldatum; 195 196 return 0; 197 } 198 199 static int bool_isvalid(struct cond_bool_datum *b) 200 { 201 if (!(b->state == 0 || b->state == 1)) 202 return 0; 203 return 1; 204 } 205 206 int cond_read_bool(struct policydb *p, struct symtab *s, void *fp) 207 { 208 char *key = NULL; 209 struct cond_bool_datum *booldatum; 210 __le32 buf[3]; 211 u32 len; 212 int rc; 213 214 booldatum = kzalloc(sizeof(*booldatum), GFP_KERNEL); 215 if (!booldatum) 216 return -ENOMEM; 217 218 rc = next_entry(buf, fp, sizeof(buf)); 219 if (rc) 220 goto err; 221 222 booldatum->value = le32_to_cpu(buf[0]); 223 booldatum->state = le32_to_cpu(buf[1]); 224 225 rc = -EINVAL; 226 if (!bool_isvalid(booldatum)) 227 goto err; 228 229 len = le32_to_cpu(buf[2]); 230 if (((len == 0) || (len == (u32)-1))) 231 goto err; 232 233 rc = -ENOMEM; 234 key = kmalloc(len + 1, GFP_KERNEL); 235 if (!key) 236 goto err; 237 rc = next_entry(key, fp, len); 238 if (rc) 239 goto err; 240 key[len] = '\0'; 241 rc = symtab_insert(s, key, booldatum); 242 if (rc) 243 goto err; 244 245 return 0; 246 err: 247 cond_destroy_bool(key, booldatum, NULL); 248 return rc; 249 } 250 251 struct cond_insertf_data { 252 struct policydb *p; 253 struct avtab_node **dst; 254 struct cond_av_list *other; 255 }; 256 257 static int cond_insertf(struct avtab *a, const struct avtab_key *k, 258 const struct avtab_datum *d, void *ptr) 259 { 260 struct cond_insertf_data *data = ptr; 261 struct policydb *p = data->p; 262 struct cond_av_list *other = data->other; 263 struct avtab_node *node_ptr; 264 u32 i; 265 bool found; 266 267 /* 268 * For type rules we have to make certain there aren't any 269 * conflicting rules by searching the te_avtab and the 270 * cond_te_avtab. 271 */ 272 if (k->specified & AVTAB_TYPE) { 273 if (avtab_search(&p->te_avtab, k)) { 274 pr_err("SELinux: type rule already exists outside of a conditional.\n"); 275 return -EINVAL; 276 } 277 /* 278 * If we are reading the false list other will be a pointer to 279 * the true list. We can have duplicate entries if there is only 280 * 1 other entry and it is in our true list. 281 * 282 * If we are reading the true list (other == NULL) there shouldn't 283 * be any other entries. 284 */ 285 if (other) { 286 node_ptr = avtab_search_node(&p->te_cond_avtab, k); 287 if (node_ptr) { 288 if (avtab_search_node_next(node_ptr, k->specified)) { 289 pr_err("SELinux: too many conflicting type rules.\n"); 290 return -EINVAL; 291 } 292 found = false; 293 for (i = 0; i < other->len; i++) { 294 if (other->nodes[i] == node_ptr) { 295 found = true; 296 break; 297 } 298 } 299 if (!found) { 300 pr_err("SELinux: conflicting type rules.\n"); 301 return -EINVAL; 302 } 303 } 304 } else { 305 if (avtab_search(&p->te_cond_avtab, k)) { 306 pr_err("SELinux: conflicting type rules when adding type rule for true.\n"); 307 return -EINVAL; 308 } 309 } 310 } 311 312 node_ptr = avtab_insert_nonunique(&p->te_cond_avtab, k, d); 313 if (!node_ptr) { 314 pr_err("SELinux: could not insert rule.\n"); 315 return -ENOMEM; 316 } 317 318 *data->dst = node_ptr; 319 return 0; 320 } 321 322 static int cond_read_av_list(struct policydb *p, void *fp, 323 struct cond_av_list *list, 324 struct cond_av_list *other) 325 { 326 int rc; 327 __le32 buf[1]; 328 u32 i, len; 329 struct cond_insertf_data data; 330 331 rc = next_entry(buf, fp, sizeof(u32)); 332 if (rc) 333 return rc; 334 335 len = le32_to_cpu(buf[0]); 336 if (len == 0) 337 return 0; 338 339 list->nodes = kcalloc(len, sizeof(*list->nodes), GFP_KERNEL); 340 if (!list->nodes) 341 return -ENOMEM; 342 343 data.p = p; 344 data.other = other; 345 for (i = 0; i < len; i++) { 346 data.dst = &list->nodes[i]; 347 rc = avtab_read_item(&p->te_cond_avtab, fp, p, cond_insertf, 348 &data); 349 if (rc) { 350 kfree(list->nodes); 351 list->nodes = NULL; 352 return rc; 353 } 354 } 355 356 list->len = len; 357 return 0; 358 } 359 360 static int expr_node_isvalid(struct policydb *p, struct cond_expr_node *expr) 361 { 362 if (expr->expr_type <= 0 || expr->expr_type > COND_LAST) { 363 pr_err("SELinux: conditional expressions uses unknown operator.\n"); 364 return 0; 365 } 366 367 if (expr->bool > 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, void *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 node->expr.nodes = kcalloc(len, sizeof(*node->expr.nodes), GFP_KERNEL); 389 if (!node->expr.nodes) 390 return -ENOMEM; 391 392 node->expr.len = len; 393 394 for (i = 0; i < len; i++) { 395 struct cond_expr_node *expr = &node->expr.nodes[i]; 396 397 rc = next_entry(buf, fp, sizeof(u32) * 2); 398 if (rc) 399 return rc; 400 401 expr->expr_type = le32_to_cpu(buf[0]); 402 expr->bool = le32_to_cpu(buf[1]); 403 404 if (!expr_node_isvalid(p, expr)) 405 return -EINVAL; 406 } 407 408 rc = cond_read_av_list(p, fp, &node->true_list, NULL); 409 if (rc) 410 return rc; 411 return cond_read_av_list(p, fp, &node->false_list, &node->true_list); 412 } 413 414 int cond_read_list(struct policydb *p, void *fp) 415 { 416 __le32 buf[1]; 417 u32 i, len; 418 int rc; 419 420 rc = next_entry(buf, fp, sizeof(buf)); 421 if (rc) 422 return rc; 423 424 len = le32_to_cpu(buf[0]); 425 426 p->cond_list = kcalloc(len, sizeof(*p->cond_list), GFP_KERNEL); 427 if (!p->cond_list) 428 return -ENOMEM; 429 430 rc = avtab_alloc(&(p->te_cond_avtab), p->te_avtab.nel); 431 if (rc) 432 goto err; 433 434 p->cond_list_len = len; 435 436 for (i = 0; i < len; i++) { 437 rc = cond_read_node(p, &p->cond_list[i], fp); 438 if (rc) 439 goto err; 440 } 441 return 0; 442 err: 443 cond_list_destroy(p); 444 p->cond_list = NULL; 445 return rc; 446 } 447 448 int cond_write_bool(void *vkey, void *datum, void *ptr) 449 { 450 char *key = vkey; 451 struct cond_bool_datum *booldatum = datum; 452 struct policy_data *pd = ptr; 453 void *fp = pd->fp; 454 __le32 buf[3]; 455 u32 len; 456 int rc; 457 458 len = strlen(key); 459 buf[0] = cpu_to_le32(booldatum->value); 460 buf[1] = cpu_to_le32(booldatum->state); 461 buf[2] = cpu_to_le32(len); 462 rc = put_entry(buf, sizeof(u32), 3, fp); 463 if (rc) 464 return rc; 465 rc = put_entry(key, 1, len, fp); 466 if (rc) 467 return rc; 468 return 0; 469 } 470 471 /* 472 * cond_write_cond_av_list doesn't write out the av_list nodes. 473 * Instead it writes out the key/value pairs from the avtab. This 474 * is necessary because there is no way to uniquely identifying rules 475 * in the avtab so it is not possible to associate individual rules 476 * in the avtab with a conditional without saving them as part of 477 * the conditional. This means that the avtab with the conditional 478 * rules will not be saved but will be rebuilt on policy load. 479 */ 480 static int cond_write_av_list(struct policydb *p, 481 struct cond_av_list *list, struct policy_file *fp) 482 { 483 __le32 buf[1]; 484 u32 i; 485 int rc; 486 487 buf[0] = cpu_to_le32(list->len); 488 rc = put_entry(buf, sizeof(u32), 1, fp); 489 if (rc) 490 return rc; 491 492 for (i = 0; i < list->len; i++) { 493 rc = avtab_write_item(p, list->nodes[i], fp); 494 if (rc) 495 return rc; 496 } 497 498 return 0; 499 } 500 501 static int cond_write_node(struct policydb *p, struct cond_node *node, 502 struct policy_file *fp) 503 { 504 __le32 buf[2]; 505 int rc; 506 u32 i; 507 508 buf[0] = cpu_to_le32(node->cur_state); 509 rc = put_entry(buf, sizeof(u32), 1, fp); 510 if (rc) 511 return rc; 512 513 buf[0] = cpu_to_le32(node->expr.len); 514 rc = put_entry(buf, sizeof(u32), 1, fp); 515 if (rc) 516 return rc; 517 518 for (i = 0; i < node->expr.len; i++) { 519 buf[0] = cpu_to_le32(node->expr.nodes[i].expr_type); 520 buf[1] = cpu_to_le32(node->expr.nodes[i].bool); 521 rc = put_entry(buf, sizeof(u32), 2, fp); 522 if (rc) 523 return rc; 524 } 525 526 rc = cond_write_av_list(p, &node->true_list, fp); 527 if (rc) 528 return rc; 529 rc = cond_write_av_list(p, &node->false_list, fp); 530 if (rc) 531 return rc; 532 533 return 0; 534 } 535 536 int cond_write_list(struct policydb *p, void *fp) 537 { 538 u32 i; 539 __le32 buf[1]; 540 int rc; 541 542 buf[0] = cpu_to_le32(p->cond_list_len); 543 rc = put_entry(buf, sizeof(u32), 1, fp); 544 if (rc) 545 return rc; 546 547 for (i = 0; i < p->cond_list_len; i++) { 548 rc = cond_write_node(p, &p->cond_list[i], fp); 549 if (rc) 550 return rc; 551 } 552 553 return 0; 554 } 555 556 void cond_compute_xperms(struct avtab *ctab, struct avtab_key *key, 557 struct extended_perms_decision *xpermd) 558 { 559 struct avtab_node *node; 560 561 if (!ctab || !key || !xpermd) 562 return; 563 564 for (node = avtab_search_node(ctab, key); node; 565 node = avtab_search_node_next(node, key->specified)) { 566 if (node->key.specified & AVTAB_ENABLED) 567 services_compute_xperms_decision(xpermd, node); 568 } 569 return; 570 571 } 572 /* Determine whether additional permissions are granted by the conditional 573 * av table, and if so, add them to the result 574 */ 575 void cond_compute_av(struct avtab *ctab, struct avtab_key *key, 576 struct av_decision *avd, struct extended_perms *xperms) 577 { 578 struct avtab_node *node; 579 580 if (!ctab || !key || !avd) 581 return; 582 583 for (node = avtab_search_node(ctab, key); node; 584 node = avtab_search_node_next(node, key->specified)) { 585 if ((u16)(AVTAB_ALLOWED|AVTAB_ENABLED) == 586 (node->key.specified & (AVTAB_ALLOWED|AVTAB_ENABLED))) 587 avd->allowed |= node->datum.u.data; 588 if ((u16)(AVTAB_AUDITDENY|AVTAB_ENABLED) == 589 (node->key.specified & (AVTAB_AUDITDENY|AVTAB_ENABLED))) 590 /* Since a '0' in an auditdeny mask represents a 591 * permission we do NOT want to audit (dontaudit), we use 592 * the '&' operand to ensure that all '0's in the mask 593 * are retained (much unlike the allow and auditallow cases). 594 */ 595 avd->auditdeny &= node->datum.u.data; 596 if ((u16)(AVTAB_AUDITALLOW|AVTAB_ENABLED) == 597 (node->key.specified & (AVTAB_AUDITALLOW|AVTAB_ENABLED))) 598 avd->auditallow |= node->datum.u.data; 599 if (xperms && (node->key.specified & AVTAB_ENABLED) && 600 (node->key.specified & AVTAB_XPERMS)) 601 services_compute_xperms_drivers(xperms, node); 602 } 603 } 604 605 static int cond_dup_av_list(struct cond_av_list *new, 606 struct cond_av_list *orig, 607 struct avtab *avtab) 608 { 609 u32 i; 610 611 memset(new, 0, sizeof(*new)); 612 613 new->nodes = kcalloc(orig->len, sizeof(*new->nodes), GFP_KERNEL); 614 if (!new->nodes) 615 return -ENOMEM; 616 617 for (i = 0; i < orig->len; i++) { 618 new->nodes[i] = avtab_insert_nonunique(avtab, 619 &orig->nodes[i]->key, 620 &orig->nodes[i]->datum); 621 if (!new->nodes[i]) 622 return -ENOMEM; 623 new->len++; 624 } 625 626 return 0; 627 } 628 629 static int duplicate_policydb_cond_list(struct policydb *newp, 630 struct policydb *origp) 631 { 632 int rc; 633 u32 i; 634 635 rc = avtab_alloc_dup(&newp->te_cond_avtab, &origp->te_cond_avtab); 636 if (rc) 637 return rc; 638 639 newp->cond_list_len = 0; 640 newp->cond_list = kcalloc(origp->cond_list_len, 641 sizeof(*newp->cond_list), 642 GFP_KERNEL); 643 if (!newp->cond_list) 644 goto error; 645 646 for (i = 0; i < origp->cond_list_len; i++) { 647 struct cond_node *newn = &newp->cond_list[i]; 648 struct cond_node *orign = &origp->cond_list[i]; 649 650 newp->cond_list_len++; 651 652 newn->cur_state = orign->cur_state; 653 newn->expr.nodes = kmemdup(orign->expr.nodes, 654 orign->expr.len * sizeof(*orign->expr.nodes), 655 GFP_KERNEL); 656 if (!newn->expr.nodes) 657 goto error; 658 659 newn->expr.len = orign->expr.len; 660 661 rc = cond_dup_av_list(&newn->true_list, &orign->true_list, 662 &newp->te_cond_avtab); 663 if (rc) 664 goto error; 665 666 rc = cond_dup_av_list(&newn->false_list, &orign->false_list, 667 &newp->te_cond_avtab); 668 if (rc) 669 goto error; 670 } 671 672 return 0; 673 674 error: 675 avtab_destroy(&newp->te_cond_avtab); 676 cond_list_destroy(newp); 677 return -ENOMEM; 678 } 679 680 static int cond_bools_destroy(void *key, void *datum, void *args) 681 { 682 /* key was not copied so no need to free here */ 683 kfree(datum); 684 return 0; 685 } 686 687 static int cond_bools_copy(struct hashtab_node *new, struct hashtab_node *orig, void *args) 688 { 689 struct cond_bool_datum *datum; 690 691 datum = kmemdup(orig->datum, sizeof(struct cond_bool_datum), 692 GFP_KERNEL); 693 if (!datum) 694 return -ENOMEM; 695 696 new->key = orig->key; /* No need to copy, never modified */ 697 new->datum = datum; 698 return 0; 699 } 700 701 static int cond_bools_index(void *key, void *datum, void *args) 702 { 703 struct cond_bool_datum *booldatum, **cond_bool_array; 704 705 booldatum = datum; 706 cond_bool_array = args; 707 cond_bool_array[booldatum->value - 1] = booldatum; 708 709 return 0; 710 } 711 712 static int duplicate_policydb_bools(struct policydb *newdb, 713 struct policydb *orig) 714 { 715 struct cond_bool_datum **cond_bool_array; 716 int rc; 717 718 cond_bool_array = kmalloc_array(orig->p_bools.nprim, 719 sizeof(*orig->bool_val_to_struct), 720 GFP_KERNEL); 721 if (!cond_bool_array) 722 return -ENOMEM; 723 724 rc = hashtab_duplicate(&newdb->p_bools.table, &orig->p_bools.table, 725 cond_bools_copy, cond_bools_destroy, NULL); 726 if (rc) { 727 kfree(cond_bool_array); 728 return -ENOMEM; 729 } 730 731 hashtab_map(&newdb->p_bools.table, cond_bools_index, cond_bool_array); 732 newdb->bool_val_to_struct = cond_bool_array; 733 734 newdb->p_bools.nprim = orig->p_bools.nprim; 735 736 return 0; 737 } 738 739 void cond_policydb_destroy_dup(struct policydb *p) 740 { 741 hashtab_map(&p->p_bools.table, cond_bools_destroy, NULL); 742 hashtab_destroy(&p->p_bools.table); 743 cond_policydb_destroy(p); 744 } 745 746 int cond_policydb_dup(struct policydb *new, struct policydb *orig) 747 { 748 cond_policydb_init(new); 749 750 if (duplicate_policydb_bools(new, orig)) 751 return -ENOMEM; 752 753 if (duplicate_policydb_cond_list(new, orig)) { 754 cond_policydb_destroy_dup(new); 755 return -ENOMEM; 756 } 757 758 return 0; 759 } 760