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->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 = kmalloc_array(p->p_bools.nprim, 170 sizeof(*p->bool_val_to_struct), 171 GFP_KERNEL); 172 if (!p->bool_val_to_struct) 173 return -ENOMEM; 174 return 0; 175 } 176 177 int cond_destroy_bool(void *key, void *datum, void *p) 178 { 179 kfree(key); 180 kfree(datum); 181 return 0; 182 } 183 184 int cond_index_bool(void *key, void *datum, void *datap) 185 { 186 struct policydb *p; 187 struct cond_bool_datum *booldatum; 188 189 booldatum = datum; 190 p = datap; 191 192 if (!booldatum->value || booldatum->value > p->p_bools.nprim) 193 return -EINVAL; 194 195 p->sym_val_to_name[SYM_BOOLS][booldatum->value - 1] = key; 196 p->bool_val_to_struct[booldatum->value - 1] = booldatum; 197 198 return 0; 199 } 200 201 static int bool_isvalid(struct cond_bool_datum *b) 202 { 203 if (!(b->state == 0 || b->state == 1)) 204 return 0; 205 return 1; 206 } 207 208 int cond_read_bool(struct policydb *p, struct symtab *s, void *fp) 209 { 210 char *key = NULL; 211 struct cond_bool_datum *booldatum; 212 __le32 buf[3]; 213 u32 len; 214 int rc; 215 216 booldatum = kzalloc(sizeof(*booldatum), GFP_KERNEL); 217 if (!booldatum) 218 return -ENOMEM; 219 220 rc = next_entry(buf, fp, sizeof(buf)); 221 if (rc) 222 goto err; 223 224 booldatum->value = le32_to_cpu(buf[0]); 225 booldatum->state = le32_to_cpu(buf[1]); 226 227 rc = -EINVAL; 228 if (!bool_isvalid(booldatum)) 229 goto err; 230 231 len = le32_to_cpu(buf[2]); 232 if (((len == 0) || (len == (u32)-1))) 233 goto err; 234 235 rc = -ENOMEM; 236 key = kmalloc(len + 1, GFP_KERNEL); 237 if (!key) 238 goto err; 239 rc = next_entry(key, fp, len); 240 if (rc) 241 goto err; 242 key[len] = '\0'; 243 rc = symtab_insert(s, key, booldatum); 244 if (rc) 245 goto err; 246 247 return 0; 248 err: 249 cond_destroy_bool(key, booldatum, NULL); 250 return rc; 251 } 252 253 struct cond_insertf_data { 254 struct policydb *p; 255 struct avtab_node **dst; 256 struct cond_av_list *other; 257 }; 258 259 static int cond_insertf(struct avtab *a, const struct avtab_key *k, 260 const struct avtab_datum *d, void *ptr) 261 { 262 struct cond_insertf_data *data = ptr; 263 struct policydb *p = data->p; 264 struct cond_av_list *other = data->other; 265 struct avtab_node *node_ptr; 266 u32 i; 267 bool found; 268 269 /* 270 * For type rules we have to make certain there aren't any 271 * conflicting rules by searching the te_avtab and the 272 * cond_te_avtab. 273 */ 274 if (k->specified & AVTAB_TYPE) { 275 if (avtab_search_node(&p->te_avtab, k)) { 276 pr_err("SELinux: type rule already exists outside of a conditional.\n"); 277 return -EINVAL; 278 } 279 /* 280 * If we are reading the false list other will be a pointer to 281 * the true list. We can have duplicate entries if there is only 282 * 1 other entry and it is in our true list. 283 * 284 * If we are reading the true list (other == NULL) there shouldn't 285 * be any other entries. 286 */ 287 if (other) { 288 node_ptr = avtab_search_node(&p->te_cond_avtab, k); 289 if (node_ptr) { 290 if (avtab_search_node_next(node_ptr, k->specified)) { 291 pr_err("SELinux: too many conflicting type rules.\n"); 292 return -EINVAL; 293 } 294 found = false; 295 for (i = 0; i < other->len; i++) { 296 if (other->nodes[i] == node_ptr) { 297 found = true; 298 break; 299 } 300 } 301 if (!found) { 302 pr_err("SELinux: conflicting type rules.\n"); 303 return -EINVAL; 304 } 305 } 306 } else { 307 if (avtab_search_node(&p->te_cond_avtab, k)) { 308 pr_err("SELinux: conflicting type rules when adding type rule for true.\n"); 309 return -EINVAL; 310 } 311 } 312 } 313 314 node_ptr = avtab_insert_nonunique(&p->te_cond_avtab, k, d); 315 if (!node_ptr) { 316 pr_err("SELinux: could not insert rule.\n"); 317 return -ENOMEM; 318 } 319 320 *data->dst = node_ptr; 321 return 0; 322 } 323 324 static int cond_read_av_list(struct policydb *p, void *fp, 325 struct cond_av_list *list, 326 struct cond_av_list *other) 327 { 328 int rc; 329 __le32 buf[1]; 330 u32 i, len; 331 struct cond_insertf_data data; 332 333 rc = next_entry(buf, fp, sizeof(u32)); 334 if (rc) 335 return rc; 336 337 len = le32_to_cpu(buf[0]); 338 if (len == 0) 339 return 0; 340 341 list->nodes = kcalloc(len, sizeof(*list->nodes), GFP_KERNEL); 342 if (!list->nodes) 343 return -ENOMEM; 344 345 data.p = p; 346 data.other = other; 347 for (i = 0; i < len; i++) { 348 data.dst = &list->nodes[i]; 349 rc = avtab_read_item(&p->te_cond_avtab, fp, p, cond_insertf, 350 &data); 351 if (rc) { 352 kfree(list->nodes); 353 list->nodes = NULL; 354 return rc; 355 } 356 } 357 358 list->len = len; 359 return 0; 360 } 361 362 static int expr_node_isvalid(struct policydb *p, struct cond_expr_node *expr) 363 { 364 if (expr->expr_type <= 0 || expr->expr_type > COND_LAST) { 365 pr_err("SELinux: conditional expressions uses unknown operator.\n"); 366 return 0; 367 } 368 369 if (expr->boolean > p->p_bools.nprim) { 370 pr_err("SELinux: conditional expressions uses unknown bool.\n"); 371 return 0; 372 } 373 return 1; 374 } 375 376 static int cond_read_node(struct policydb *p, struct cond_node *node, void *fp) 377 { 378 __le32 buf[2]; 379 u32 i, len; 380 int rc; 381 382 rc = next_entry(buf, fp, sizeof(u32) * 2); 383 if (rc) 384 return rc; 385 386 node->cur_state = le32_to_cpu(buf[0]); 387 388 /* expr */ 389 len = le32_to_cpu(buf[1]); 390 node->expr.nodes = kcalloc(len, sizeof(*node->expr.nodes), GFP_KERNEL); 391 if (!node->expr.nodes) 392 return -ENOMEM; 393 394 node->expr.len = len; 395 396 for (i = 0; i < len; i++) { 397 struct cond_expr_node *expr = &node->expr.nodes[i]; 398 399 rc = next_entry(buf, fp, sizeof(u32) * 2); 400 if (rc) 401 return rc; 402 403 expr->expr_type = le32_to_cpu(buf[0]); 404 expr->boolean = le32_to_cpu(buf[1]); 405 406 if (!expr_node_isvalid(p, expr)) 407 return -EINVAL; 408 } 409 410 rc = cond_read_av_list(p, fp, &node->true_list, NULL); 411 if (rc) 412 return rc; 413 return cond_read_av_list(p, fp, &node->false_list, &node->true_list); 414 } 415 416 int cond_read_list(struct policydb *p, void *fp) 417 { 418 __le32 buf[1]; 419 u32 i, len; 420 int rc; 421 422 rc = next_entry(buf, fp, sizeof(buf)); 423 if (rc) 424 return rc; 425 426 len = le32_to_cpu(buf[0]); 427 428 p->cond_list = kcalloc(len, sizeof(*p->cond_list), GFP_KERNEL); 429 if (!p->cond_list) 430 return -ENOMEM; 431 432 rc = avtab_alloc(&(p->te_cond_avtab), p->te_avtab.nel); 433 if (rc) 434 goto err; 435 436 p->cond_list_len = len; 437 438 for (i = 0; i < len; i++) { 439 rc = cond_read_node(p, &p->cond_list[i], fp); 440 if (rc) 441 goto err; 442 } 443 return 0; 444 err: 445 cond_list_destroy(p); 446 return rc; 447 } 448 449 int cond_write_bool(void *vkey, void *datum, void *ptr) 450 { 451 char *key = vkey; 452 struct cond_bool_datum *booldatum = datum; 453 struct policy_data *pd = ptr; 454 void *fp = pd->fp; 455 __le32 buf[3]; 456 u32 len; 457 int rc; 458 459 len = strlen(key); 460 buf[0] = cpu_to_le32(booldatum->value); 461 buf[1] = cpu_to_le32(booldatum->state); 462 buf[2] = cpu_to_le32(len); 463 rc = put_entry(buf, sizeof(u32), 3, fp); 464 if (rc) 465 return rc; 466 rc = put_entry(key, 1, len, fp); 467 if (rc) 468 return rc; 469 return 0; 470 } 471 472 /* 473 * cond_write_cond_av_list doesn't write out the av_list nodes. 474 * Instead it writes out the key/value pairs from the avtab. This 475 * is necessary because there is no way to uniquely identifying rules 476 * in the avtab so it is not possible to associate individual rules 477 * in the avtab with a conditional without saving them as part of 478 * the conditional. This means that the avtab with the conditional 479 * rules will not be saved but will be rebuilt on policy load. 480 */ 481 static int cond_write_av_list(struct policydb *p, 482 struct cond_av_list *list, struct policy_file *fp) 483 { 484 __le32 buf[1]; 485 u32 i; 486 int rc; 487 488 buf[0] = cpu_to_le32(list->len); 489 rc = put_entry(buf, sizeof(u32), 1, fp); 490 if (rc) 491 return rc; 492 493 for (i = 0; i < list->len; i++) { 494 rc = avtab_write_item(p, list->nodes[i], fp); 495 if (rc) 496 return rc; 497 } 498 499 return 0; 500 } 501 502 static int cond_write_node(struct policydb *p, struct cond_node *node, 503 struct policy_file *fp) 504 { 505 __le32 buf[2]; 506 int rc; 507 u32 i; 508 509 buf[0] = cpu_to_le32(node->cur_state); 510 rc = put_entry(buf, sizeof(u32), 1, fp); 511 if (rc) 512 return rc; 513 514 buf[0] = cpu_to_le32(node->expr.len); 515 rc = put_entry(buf, sizeof(u32), 1, fp); 516 if (rc) 517 return rc; 518 519 for (i = 0; i < node->expr.len; i++) { 520 buf[0] = cpu_to_le32(node->expr.nodes[i].expr_type); 521 buf[1] = cpu_to_le32(node->expr.nodes[i].boolean); 522 rc = put_entry(buf, sizeof(u32), 2, fp); 523 if (rc) 524 return rc; 525 } 526 527 rc = cond_write_av_list(p, &node->true_list, fp); 528 if (rc) 529 return rc; 530 rc = cond_write_av_list(p, &node->false_list, fp); 531 if (rc) 532 return rc; 533 534 return 0; 535 } 536 537 int cond_write_list(struct policydb *p, void *fp) 538 { 539 u32 i; 540 __le32 buf[1]; 541 int rc; 542 543 buf[0] = cpu_to_le32(p->cond_list_len); 544 rc = put_entry(buf, sizeof(u32), 1, fp); 545 if (rc) 546 return rc; 547 548 for (i = 0; i < p->cond_list_len; i++) { 549 rc = cond_write_node(p, &p->cond_list[i], fp); 550 if (rc) 551 return rc; 552 } 553 554 return 0; 555 } 556 557 void cond_compute_xperms(struct avtab *ctab, struct avtab_key *key, 558 struct extended_perms_decision *xpermd) 559 { 560 struct avtab_node *node; 561 562 if (!ctab || !key || !xpermd) 563 return; 564 565 for (node = avtab_search_node(ctab, key); node; 566 node = avtab_search_node_next(node, key->specified)) { 567 if (node->key.specified & AVTAB_ENABLED) 568 services_compute_xperms_decision(xpermd, node); 569 } 570 } 571 /* Determine whether additional permissions are granted by the conditional 572 * av table, and if so, add them to the result 573 */ 574 void cond_compute_av(struct avtab *ctab, struct avtab_key *key, 575 struct av_decision *avd, struct extended_perms *xperms) 576 { 577 struct avtab_node *node; 578 579 if (!ctab || !key || !avd) 580 return; 581 582 for (node = avtab_search_node(ctab, key); node; 583 node = avtab_search_node_next(node, key->specified)) { 584 if ((u16)(AVTAB_ALLOWED|AVTAB_ENABLED) == 585 (node->key.specified & (AVTAB_ALLOWED|AVTAB_ENABLED))) 586 avd->allowed |= node->datum.u.data; 587 if ((u16)(AVTAB_AUDITDENY|AVTAB_ENABLED) == 588 (node->key.specified & (AVTAB_AUDITDENY|AVTAB_ENABLED))) 589 /* Since a '0' in an auditdeny mask represents a 590 * permission we do NOT want to audit (dontaudit), we use 591 * the '&' operand to ensure that all '0's in the mask 592 * are retained (much unlike the allow and auditallow cases). 593 */ 594 avd->auditdeny &= node->datum.u.data; 595 if ((u16)(AVTAB_AUDITALLOW|AVTAB_ENABLED) == 596 (node->key.specified & (AVTAB_AUDITALLOW|AVTAB_ENABLED))) 597 avd->auditallow |= node->datum.u.data; 598 if (xperms && (node->key.specified & AVTAB_ENABLED) && 599 (node->key.specified & AVTAB_XPERMS)) 600 services_compute_xperms_drivers(xperms, node); 601 } 602 } 603 604 static int cond_dup_av_list(struct cond_av_list *new, 605 struct cond_av_list *orig, 606 struct avtab *avtab) 607 { 608 u32 i; 609 610 memset(new, 0, sizeof(*new)); 611 612 new->nodes = kcalloc(orig->len, sizeof(*new->nodes), GFP_KERNEL); 613 if (!new->nodes) 614 return -ENOMEM; 615 616 for (i = 0; i < orig->len; i++) { 617 new->nodes[i] = avtab_insert_nonunique(avtab, 618 &orig->nodes[i]->key, 619 &orig->nodes[i]->datum); 620 if (!new->nodes[i]) 621 return -ENOMEM; 622 new->len++; 623 } 624 625 return 0; 626 } 627 628 static int duplicate_policydb_cond_list(struct policydb *newp, 629 struct policydb *origp) 630 { 631 int rc; 632 u32 i; 633 634 rc = avtab_alloc_dup(&newp->te_cond_avtab, &origp->te_cond_avtab); 635 if (rc) 636 return rc; 637 638 newp->cond_list_len = 0; 639 newp->cond_list = kcalloc(origp->cond_list_len, 640 sizeof(*newp->cond_list), 641 GFP_KERNEL); 642 if (!newp->cond_list) 643 goto error; 644 645 for (i = 0; i < origp->cond_list_len; i++) { 646 struct cond_node *newn = &newp->cond_list[i]; 647 struct cond_node *orign = &origp->cond_list[i]; 648 649 newp->cond_list_len++; 650 651 newn->cur_state = orign->cur_state; 652 newn->expr.nodes = kmemdup(orign->expr.nodes, 653 orign->expr.len * sizeof(*orign->expr.nodes), 654 GFP_KERNEL); 655 if (!newn->expr.nodes) 656 goto error; 657 658 newn->expr.len = orign->expr.len; 659 660 rc = cond_dup_av_list(&newn->true_list, &orign->true_list, 661 &newp->te_cond_avtab); 662 if (rc) 663 goto error; 664 665 rc = cond_dup_av_list(&newn->false_list, &orign->false_list, 666 &newp->te_cond_avtab); 667 if (rc) 668 goto error; 669 } 670 671 return 0; 672 673 error: 674 avtab_destroy(&newp->te_cond_avtab); 675 cond_list_destroy(newp); 676 return -ENOMEM; 677 } 678 679 static int cond_bools_destroy(void *key, void *datum, void *args) 680 { 681 /* key was not copied so no need to free here */ 682 kfree(datum); 683 return 0; 684 } 685 686 static int cond_bools_copy(struct hashtab_node *new, struct hashtab_node *orig, void *args) 687 { 688 struct cond_bool_datum *datum; 689 690 datum = kmemdup(orig->datum, sizeof(struct cond_bool_datum), 691 GFP_KERNEL); 692 if (!datum) 693 return -ENOMEM; 694 695 new->key = orig->key; /* No need to copy, never modified */ 696 new->datum = datum; 697 return 0; 698 } 699 700 static int cond_bools_index(void *key, void *datum, void *args) 701 { 702 struct cond_bool_datum *booldatum, **cond_bool_array; 703 704 booldatum = datum; 705 cond_bool_array = args; 706 cond_bool_array[booldatum->value - 1] = booldatum; 707 708 return 0; 709 } 710 711 static int duplicate_policydb_bools(struct policydb *newdb, 712 struct policydb *orig) 713 { 714 struct cond_bool_datum **cond_bool_array; 715 int rc; 716 717 cond_bool_array = kmalloc_array(orig->p_bools.nprim, 718 sizeof(*orig->bool_val_to_struct), 719 GFP_KERNEL); 720 if (!cond_bool_array) 721 return -ENOMEM; 722 723 rc = hashtab_duplicate(&newdb->p_bools.table, &orig->p_bools.table, 724 cond_bools_copy, cond_bools_destroy, NULL); 725 if (rc) { 726 kfree(cond_bool_array); 727 return -ENOMEM; 728 } 729 730 hashtab_map(&newdb->p_bools.table, cond_bools_index, cond_bool_array); 731 newdb->bool_val_to_struct = cond_bool_array; 732 733 newdb->p_bools.nprim = orig->p_bools.nprim; 734 735 return 0; 736 } 737 738 void cond_policydb_destroy_dup(struct policydb *p) 739 { 740 hashtab_map(&p->p_bools.table, cond_bools_destroy, NULL); 741 hashtab_destroy(&p->p_bools.table); 742 cond_policydb_destroy(p); 743 } 744 745 int cond_policydb_dup(struct policydb *new, struct policydb *orig) 746 { 747 cond_policydb_init(new); 748 749 if (duplicate_policydb_bools(new, orig)) 750 return -ENOMEM; 751 752 if (duplicate_policydb_cond_list(new, orig)) { 753 cond_policydb_destroy_dup(new); 754 return -ENOMEM; 755 } 756 757 return 0; 758 } 759