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 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_node(&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, 289 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_node(&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 } 322 323 static 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 } 360 361 static 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->boolean > p->p_bools.nprim) { 369 pr_err("SELinux: conditional expressions uses unknown bool.\n"); 370 return 0; 371 } 372 return 1; 373 } 374 375 static 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->boolean = 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 } 414 415 int 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; 443 err: 444 cond_list_destroy(p); 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, struct cond_av_list *list, 481 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].boolean); 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 } 570 /* Determine whether additional permissions are granted by the conditional 571 * av table, and if so, add them to the result 572 */ 573 void cond_compute_av(struct avtab *ctab, struct avtab_key *key, 574 struct av_decision *avd, struct extended_perms *xperms) 575 { 576 struct avtab_node *node; 577 578 if (!ctab || !key || !avd) 579 return; 580 581 for (node = avtab_search_node(ctab, key); node; 582 node = avtab_search_node_next(node, key->specified)) { 583 if ((u16)(AVTAB_ALLOWED | AVTAB_ENABLED) == 584 (node->key.specified & (AVTAB_ALLOWED | AVTAB_ENABLED))) 585 avd->allowed |= node->datum.u.data; 586 if ((u16)(AVTAB_AUDITDENY | AVTAB_ENABLED) == 587 (node->key.specified & (AVTAB_AUDITDENY | AVTAB_ENABLED))) 588 /* Since a '0' in an auditdeny mask represents a 589 * permission we do NOT want to audit (dontaudit), we use 590 * the '&' operand to ensure that all '0's in the mask 591 * are retained (much unlike the allow and auditallow cases). 592 */ 593 avd->auditdeny &= node->datum.u.data; 594 if ((u16)(AVTAB_AUDITALLOW | AVTAB_ENABLED) == 595 (node->key.specified & (AVTAB_AUDITALLOW | AVTAB_ENABLED))) 596 avd->auditallow |= node->datum.u.data; 597 if (xperms && (node->key.specified & AVTAB_ENABLED) && 598 (node->key.specified & AVTAB_XPERMS)) 599 services_compute_xperms_drivers(xperms, node); 600 } 601 } 602 603 static int cond_dup_av_list(struct cond_av_list *new, struct cond_av_list *orig, 604 struct avtab *avtab) 605 { 606 u32 i; 607 608 memset(new, 0, sizeof(*new)); 609 610 new->nodes = kcalloc(orig->len, sizeof(*new->nodes), GFP_KERNEL); 611 if (!new->nodes) 612 return -ENOMEM; 613 614 for (i = 0; i < orig->len; i++) { 615 new->nodes[i] = avtab_insert_nonunique( 616 avtab, &orig->nodes[i]->key, &orig->nodes[i]->datum); 617 if (!new->nodes[i]) 618 return -ENOMEM; 619 new->len++; 620 } 621 622 return 0; 623 } 624 625 static int duplicate_policydb_cond_list(struct policydb *newp, 626 struct policydb *origp) 627 { 628 int rc; 629 u32 i; 630 631 rc = avtab_alloc_dup(&newp->te_cond_avtab, &origp->te_cond_avtab); 632 if (rc) 633 return rc; 634 635 newp->cond_list_len = 0; 636 newp->cond_list = kcalloc(origp->cond_list_len, 637 sizeof(*newp->cond_list), GFP_KERNEL); 638 if (!newp->cond_list) 639 goto error; 640 641 for (i = 0; i < origp->cond_list_len; i++) { 642 struct cond_node *newn = &newp->cond_list[i]; 643 struct cond_node *orign = &origp->cond_list[i]; 644 645 newp->cond_list_len++; 646 647 newn->cur_state = orign->cur_state; 648 newn->expr.nodes = 649 kmemdup(orign->expr.nodes, 650 orign->expr.len * sizeof(*orign->expr.nodes), 651 GFP_KERNEL); 652 if (!newn->expr.nodes) 653 goto error; 654 655 newn->expr.len = orign->expr.len; 656 657 rc = cond_dup_av_list(&newn->true_list, &orign->true_list, 658 &newp->te_cond_avtab); 659 if (rc) 660 goto error; 661 662 rc = cond_dup_av_list(&newn->false_list, &orign->false_list, 663 &newp->te_cond_avtab); 664 if (rc) 665 goto error; 666 } 667 668 return 0; 669 670 error: 671 avtab_destroy(&newp->te_cond_avtab); 672 cond_list_destroy(newp); 673 return -ENOMEM; 674 } 675 676 static int cond_bools_destroy(void *key, void *datum, void *args) 677 { 678 /* key was not copied so no need to free here */ 679 kfree(datum); 680 return 0; 681 } 682 683 static int cond_bools_copy(struct hashtab_node *new, struct hashtab_node *orig, 684 void *args) 685 { 686 struct cond_bool_datum *datum; 687 688 datum = kmemdup(orig->datum, sizeof(struct cond_bool_datum), 689 GFP_KERNEL); 690 if (!datum) 691 return -ENOMEM; 692 693 new->key = orig->key; /* No need to copy, never modified */ 694 new->datum = datum; 695 return 0; 696 } 697 698 static int cond_bools_index(void *key, void *datum, void *args) 699 { 700 struct cond_bool_datum *booldatum, **cond_bool_array; 701 702 booldatum = datum; 703 cond_bool_array = args; 704 cond_bool_array[booldatum->value - 1] = booldatum; 705 706 return 0; 707 } 708 709 static int duplicate_policydb_bools(struct policydb *newdb, 710 struct policydb *orig) 711 { 712 struct cond_bool_datum **cond_bool_array; 713 int rc; 714 715 cond_bool_array = kmalloc_array(orig->p_bools.nprim, 716 sizeof(*orig->bool_val_to_struct), 717 GFP_KERNEL); 718 if (!cond_bool_array) 719 return -ENOMEM; 720 721 rc = hashtab_duplicate(&newdb->p_bools.table, &orig->p_bools.table, 722 cond_bools_copy, cond_bools_destroy, NULL); 723 if (rc) { 724 kfree(cond_bool_array); 725 return -ENOMEM; 726 } 727 728 hashtab_map(&newdb->p_bools.table, cond_bools_index, cond_bool_array); 729 newdb->bool_val_to_struct = cond_bool_array; 730 731 newdb->p_bools.nprim = orig->p_bools.nprim; 732 733 return 0; 734 } 735 736 void cond_policydb_destroy_dup(struct policydb *p) 737 { 738 hashtab_map(&p->p_bools.table, cond_bools_destroy, NULL); 739 hashtab_destroy(&p->p_bools.table); 740 cond_policydb_destroy(p); 741 } 742 743 int cond_policydb_dup(struct policydb *new, struct policydb *orig) 744 { 745 cond_policydb_init(new); 746 747 if (duplicate_policydb_bools(new, orig)) 748 return -ENOMEM; 749 750 if (duplicate_policydb_cond_list(new, orig)) { 751 cond_policydb_destroy_dup(new); 752 return -ENOMEM; 753 } 754 755 return 0; 756 } 757