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 */ 24static 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 */ 92static 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 123void 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 131void 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 140static 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 148static 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 159void 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 166int 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 177int cond_destroy_bool(void *key, void *datum, void *p) 178{ 179 kfree(key); 180 kfree(datum); 181 return 0; 182} 183 184int 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 201static 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 208int 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; 248err: 249 cond_destroy_bool(key, booldatum, NULL); 250 return rc; 251} 252 253struct cond_insertf_data { 254 struct policydb *p; 255 struct avtab_node **dst; 256 struct cond_av_list *other; 257}; 258 259static int cond_insertf(struct avtab *a, struct avtab_key *k, struct avtab_datum *d, void *ptr) 260{ 261 struct cond_insertf_data *data = ptr; 262 struct policydb *p = data->p; 263 struct cond_av_list *other = data->other; 264 struct avtab_node *node_ptr; 265 u32 i; 266 bool found; 267 268 /* 269 * For type rules we have to make certain there aren't any 270 * conflicting rules by searching the te_avtab and the 271 * cond_te_avtab. 272 */ 273 if (k->specified & AVTAB_TYPE) { 274 if (avtab_search(&p->te_avtab, k)) { 275 pr_err("SELinux: type rule already exists outside of a conditional.\n"); 276 return -EINVAL; 277 } 278 /* 279 * If we are reading the false list other will be a pointer to 280 * the true list. We can have duplicate entries if there is only 281 * 1 other entry and it is in our true list. 282 * 283 * If we are reading the true list (other == NULL) there shouldn't 284 * be any other entries. 285 */ 286 if (other) { 287 node_ptr = avtab_search_node(&p->te_cond_avtab, k); 288 if (node_ptr) { 289 if (avtab_search_node_next(node_ptr, k->specified)) { 290 pr_err("SELinux: too many conflicting type rules.\n"); 291 return -EINVAL; 292 } 293 found = false; 294 for (i = 0; i < other->len; i++) { 295 if (other->nodes[i] == node_ptr) { 296 found = true; 297 break; 298 } 299 } 300 if (!found) { 301 pr_err("SELinux: conflicting type rules.\n"); 302 return -EINVAL; 303 } 304 } 305 } else { 306 if (avtab_search(&p->te_cond_avtab, k)) { 307 pr_err("SELinux: conflicting type rules when adding type rule for true.\n"); 308 return -EINVAL; 309 } 310 } 311 } 312 313 node_ptr = avtab_insert_nonunique(&p->te_cond_avtab, k, d); 314 if (!node_ptr) { 315 pr_err("SELinux: could not insert rule.\n"); 316 return -ENOMEM; 317 } 318 319 *data->dst = node_ptr; 320 return 0; 321} 322 323static int cond_read_av_list(struct policydb *p, void *fp, 324 struct cond_av_list *list, 325 struct cond_av_list *other) 326{ 327 int rc; 328 __le32 buf[1]; 329 u32 i, len; 330 struct cond_insertf_data data; 331 332 rc = next_entry(buf, fp, sizeof(u32)); 333 if (rc) 334 return rc; 335 336 len = le32_to_cpu(buf[0]); 337 if (len == 0) 338 return 0; 339 340 list->nodes = kcalloc(len, sizeof(*list->nodes), GFP_KERNEL); 341 if (!list->nodes) 342 return -ENOMEM; 343 344 data.p = p; 345 data.other = other; 346 for (i = 0; i < len; i++) { 347 data.dst = &list->nodes[i]; 348 rc = avtab_read_item(&p->te_cond_avtab, fp, p, cond_insertf, 349 &data); 350 if (rc) { 351 kfree(list->nodes); 352 list->nodes = NULL; 353 return rc; 354 } 355 } 356 357 list->len = len; 358 return 0; 359} 360 361static int expr_node_isvalid(struct policydb *p, struct cond_expr_node *expr) 362{ 363 if (expr->expr_type <= 0 || expr->expr_type > COND_LAST) { 364 pr_err("SELinux: conditional expressions uses unknown operator.\n"); 365 return 0; 366 } 367 368 if (expr->bool > p->p_bools.nprim) { 369 pr_err("SELinux: conditional expressions uses unknown bool.\n"); 370 return 0; 371 } 372 return 1; 373} 374 375static int cond_read_node(struct policydb *p, struct cond_node *node, void *fp) 376{ 377 __le32 buf[2]; 378 u32 i, len; 379 int rc; 380 381 rc = next_entry(buf, fp, sizeof(u32) * 2); 382 if (rc) 383 return rc; 384 385 node->cur_state = le32_to_cpu(buf[0]); 386 387 /* expr */ 388 len = le32_to_cpu(buf[1]); 389 node->expr.nodes = kcalloc(len, sizeof(*node->expr.nodes), GFP_KERNEL); 390 if (!node->expr.nodes) 391 return -ENOMEM; 392 393 node->expr.len = len; 394 395 for (i = 0; i < len; i++) { 396 struct cond_expr_node *expr = &node->expr.nodes[i]; 397 398 rc = next_entry(buf, fp, sizeof(u32) * 2); 399 if (rc) 400 return rc; 401 402 expr->expr_type = le32_to_cpu(buf[0]); 403 expr->bool = le32_to_cpu(buf[1]); 404 405 if (!expr_node_isvalid(p, expr)) 406 return -EINVAL; 407 } 408 409 rc = cond_read_av_list(p, fp, &node->true_list, NULL); 410 if (rc) 411 return rc; 412 return cond_read_av_list(p, fp, &node->false_list, &node->true_list); 413} 414 415int cond_read_list(struct policydb *p, void *fp) 416{ 417 __le32 buf[1]; 418 u32 i, len; 419 int rc; 420 421 rc = next_entry(buf, fp, sizeof(buf)); 422 if (rc) 423 return rc; 424 425 len = le32_to_cpu(buf[0]); 426 427 p->cond_list = kcalloc(len, sizeof(*p->cond_list), GFP_KERNEL); 428 if (!p->cond_list) 429 return -ENOMEM; 430 431 rc = avtab_alloc(&(p->te_cond_avtab), p->te_avtab.nel); 432 if (rc) 433 goto err; 434 435 p->cond_list_len = len; 436 437 for (i = 0; i < len; i++) { 438 rc = cond_read_node(p, &p->cond_list[i], fp); 439 if (rc) 440 goto err; 441 } 442 return 0; 443err: 444 cond_list_destroy(p); 445 return rc; 446} 447 448int 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 */ 480static 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 501static 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 536int 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 556void 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 */ 575void 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 605static 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 629static int duplicate_policydb_cond_list(struct policydb *newp, 630 struct policydb *origp) 631{ 632 int rc, i, j; 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 = kcalloc(orign->expr.len, 653 sizeof(*newn->expr.nodes), GFP_KERNEL); 654 if (!newn->expr.nodes) 655 goto error; 656 for (j = 0; j < orign->expr.len; j++) 657 newn->expr.nodes[j] = orign->expr.nodes[j]; 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 673error: 674 avtab_destroy(&newp->te_cond_avtab); 675 cond_list_destroy(newp); 676 return -ENOMEM; 677} 678 679static 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 686static 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 700static 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 711static 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 738void 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 745int 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