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