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 hashtab *h, 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 = hashtab_insert(h, 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, struct avtab_key *k, struct avtab_datum *d, void *ptr) 258 { 259 struct cond_insertf_data *data = ptr; 260 struct policydb *p = data->p; 261 struct cond_av_list *other = data->other; 262 struct avtab_node *node_ptr; 263 u32 i; 264 bool found; 265 266 /* 267 * For type rules we have to make certain there aren't any 268 * conflicting rules by searching the te_avtab and the 269 * cond_te_avtab. 270 */ 271 if (k->specified & AVTAB_TYPE) { 272 if (avtab_search(&p->te_avtab, k)) { 273 pr_err("SELinux: type rule already exists outside of a conditional.\n"); 274 return -EINVAL; 275 } 276 /* 277 * If we are reading the false list other will be a pointer to 278 * the true list. We can have duplicate entries if there is only 279 * 1 other entry and it is in our true list. 280 * 281 * If we are reading the true list (other == NULL) there shouldn't 282 * be any other entries. 283 */ 284 if (other) { 285 node_ptr = avtab_search_node(&p->te_cond_avtab, k); 286 if (node_ptr) { 287 if (avtab_search_node_next(node_ptr, k->specified)) { 288 pr_err("SELinux: too many conflicting type rules.\n"); 289 return -EINVAL; 290 } 291 found = false; 292 for (i = 0; i < other->len; i++) { 293 if (other->nodes[i] == node_ptr) { 294 found = true; 295 break; 296 } 297 } 298 if (!found) { 299 pr_err("SELinux: conflicting type rules.\n"); 300 return -EINVAL; 301 } 302 } 303 } else { 304 if (avtab_search(&p->te_cond_avtab, k)) { 305 pr_err("SELinux: conflicting type rules when adding type rule for true.\n"); 306 return -EINVAL; 307 } 308 } 309 } 310 311 node_ptr = avtab_insert_nonunique(&p->te_cond_avtab, k, d); 312 if (!node_ptr) { 313 pr_err("SELinux: could not insert rule.\n"); 314 return -ENOMEM; 315 } 316 317 *data->dst = node_ptr; 318 return 0; 319 } 320 321 static int cond_read_av_list(struct policydb *p, void *fp, 322 struct cond_av_list *list, 323 struct cond_av_list *other) 324 { 325 int rc; 326 __le32 buf[1]; 327 u32 i, len; 328 struct cond_insertf_data data; 329 330 rc = next_entry(buf, fp, sizeof(u32)); 331 if (rc) 332 return rc; 333 334 len = le32_to_cpu(buf[0]); 335 if (len == 0) 336 return 0; 337 338 list->nodes = kcalloc(len, sizeof(*list->nodes), GFP_KERNEL); 339 if (!list->nodes) 340 return -ENOMEM; 341 342 data.p = p; 343 data.other = other; 344 for (i = 0; i < len; i++) { 345 data.dst = &list->nodes[i]; 346 rc = avtab_read_item(&p->te_cond_avtab, fp, p, cond_insertf, 347 &data); 348 if (rc) { 349 kfree(list->nodes); 350 list->nodes = NULL; 351 return rc; 352 } 353 } 354 355 list->len = len; 356 return 0; 357 } 358 359 static int expr_node_isvalid(struct policydb *p, struct cond_expr_node *expr) 360 { 361 if (expr->expr_type <= 0 || expr->expr_type > COND_LAST) { 362 pr_err("SELinux: conditional expressions uses unknown operator.\n"); 363 return 0; 364 } 365 366 if (expr->bool > p->p_bools.nprim) { 367 pr_err("SELinux: conditional expressions uses unknown bool.\n"); 368 return 0; 369 } 370 return 1; 371 } 372 373 static int cond_read_node(struct policydb *p, struct cond_node *node, void *fp) 374 { 375 __le32 buf[2]; 376 u32 i, len; 377 int rc; 378 379 rc = next_entry(buf, fp, sizeof(u32) * 2); 380 if (rc) 381 return rc; 382 383 node->cur_state = le32_to_cpu(buf[0]); 384 385 /* expr */ 386 len = le32_to_cpu(buf[1]); 387 node->expr.nodes = kcalloc(len, sizeof(*node->expr.nodes), GFP_KERNEL); 388 if (!node->expr.nodes) 389 return -ENOMEM; 390 391 node->expr.len = len; 392 393 for (i = 0; i < len; i++) { 394 struct cond_expr_node *expr = &node->expr.nodes[i]; 395 396 rc = next_entry(buf, fp, sizeof(u32) * 2); 397 if (rc) 398 return rc; 399 400 expr->expr_type = le32_to_cpu(buf[0]); 401 expr->bool = le32_to_cpu(buf[1]); 402 403 if (!expr_node_isvalid(p, expr)) 404 return -EINVAL; 405 } 406 407 rc = cond_read_av_list(p, fp, &node->true_list, NULL); 408 if (rc) 409 return rc; 410 return cond_read_av_list(p, fp, &node->false_list, &node->true_list); 411 } 412 413 int cond_read_list(struct policydb *p, void *fp) 414 { 415 __le32 buf[1]; 416 u32 i, len; 417 int rc; 418 419 rc = next_entry(buf, fp, sizeof buf); 420 if (rc) 421 return rc; 422 423 len = le32_to_cpu(buf[0]); 424 425 p->cond_list = kcalloc(len, sizeof(*p->cond_list), GFP_KERNEL); 426 if (!p->cond_list) 427 return -ENOMEM; 428 429 rc = avtab_alloc(&(p->te_cond_avtab), p->te_avtab.nel); 430 if (rc) 431 goto err; 432 433 p->cond_list_len = len; 434 435 for (i = 0; i < len; i++) { 436 rc = cond_read_node(p, &p->cond_list[i], fp); 437 if (rc) 438 goto err; 439 } 440 return 0; 441 err: 442 cond_list_destroy(p); 443 p->cond_list = NULL; 444 return rc; 445 } 446 447 int cond_write_bool(void *vkey, void *datum, void *ptr) 448 { 449 char *key = vkey; 450 struct cond_bool_datum *booldatum = datum; 451 struct policy_data *pd = ptr; 452 void *fp = pd->fp; 453 __le32 buf[3]; 454 u32 len; 455 int rc; 456 457 len = strlen(key); 458 buf[0] = cpu_to_le32(booldatum->value); 459 buf[1] = cpu_to_le32(booldatum->state); 460 buf[2] = cpu_to_le32(len); 461 rc = put_entry(buf, sizeof(u32), 3, fp); 462 if (rc) 463 return rc; 464 rc = put_entry(key, 1, len, fp); 465 if (rc) 466 return rc; 467 return 0; 468 } 469 470 /* 471 * cond_write_cond_av_list doesn't write out the av_list nodes. 472 * Instead it writes out the key/value pairs from the avtab. This 473 * is necessary because there is no way to uniquely identifying rules 474 * in the avtab so it is not possible to associate individual rules 475 * in the avtab with a conditional without saving them as part of 476 * the conditional. This means that the avtab with the conditional 477 * rules will not be saved but will be rebuilt on policy load. 478 */ 479 static int cond_write_av_list(struct policydb *p, 480 struct cond_av_list *list, struct policy_file *fp) 481 { 482 __le32 buf[1]; 483 u32 i; 484 int rc; 485 486 buf[0] = cpu_to_le32(list->len); 487 rc = put_entry(buf, sizeof(u32), 1, fp); 488 if (rc) 489 return rc; 490 491 for (i = 0; i < list->len; i++) { 492 rc = avtab_write_item(p, list->nodes[i], fp); 493 if (rc) 494 return rc; 495 } 496 497 return 0; 498 } 499 500 static int cond_write_node(struct policydb *p, struct cond_node *node, 501 struct policy_file *fp) 502 { 503 __le32 buf[2]; 504 int rc; 505 u32 i; 506 507 buf[0] = cpu_to_le32(node->cur_state); 508 rc = put_entry(buf, sizeof(u32), 1, fp); 509 if (rc) 510 return rc; 511 512 buf[0] = cpu_to_le32(node->expr.len); 513 rc = put_entry(buf, sizeof(u32), 1, fp); 514 if (rc) 515 return rc; 516 517 for (i = 0; i < node->expr.len; i++) { 518 buf[0] = cpu_to_le32(node->expr.nodes[i].expr_type); 519 buf[1] = cpu_to_le32(node->expr.nodes[i].bool); 520 rc = put_entry(buf, sizeof(u32), 2, fp); 521 if (rc) 522 return rc; 523 } 524 525 rc = cond_write_av_list(p, &node->true_list, fp); 526 if (rc) 527 return rc; 528 rc = cond_write_av_list(p, &node->false_list, fp); 529 if (rc) 530 return rc; 531 532 return 0; 533 } 534 535 int cond_write_list(struct policydb *p, void *fp) 536 { 537 u32 i; 538 __le32 buf[1]; 539 int rc; 540 541 buf[0] = cpu_to_le32(p->cond_list_len); 542 rc = put_entry(buf, sizeof(u32), 1, fp); 543 if (rc) 544 return rc; 545 546 for (i = 0; i < p->cond_list_len; i++) { 547 rc = cond_write_node(p, &p->cond_list[i], fp); 548 if (rc) 549 return rc; 550 } 551 552 return 0; 553 } 554 555 void cond_compute_xperms(struct avtab *ctab, struct avtab_key *key, 556 struct extended_perms_decision *xpermd) 557 { 558 struct avtab_node *node; 559 560 if (!ctab || !key || !xpermd) 561 return; 562 563 for (node = avtab_search_node(ctab, key); node; 564 node = avtab_search_node_next(node, key->specified)) { 565 if (node->key.specified & AVTAB_ENABLED) 566 services_compute_xperms_decision(xpermd, node); 567 } 568 return; 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