1 /* 2 * Copyright 2014-2016 by Open Source Security, Inc., Brad Spengler <[email protected]> 3 * and PaX Team <[email protected]> 4 * Licensed under the GPL v2 5 * 6 * Note: the choice of the license means that the compilation process is 7 * NOT 'eligible' as defined by gcc's library exception to the GPL v3, 8 * but for the kernel it doesn't matter since it doesn't link against 9 * any of the gcc libraries 10 * 11 * Usage: 12 * $ # for 4.5/4.6/C based 4.7 13 * $ gcc -I`gcc -print-file-name=plugin`/include -I`gcc -print-file-name=plugin`/include/c-family -fPIC -shared -O2 -o randomize_layout_plugin.so randomize_layout_plugin.c 14 * $ # for C++ based 4.7/4.8+ 15 * $ g++ -I`g++ -print-file-name=plugin`/include -I`g++ -print-file-name=plugin`/include/c-family -fPIC -shared -O2 -o randomize_layout_plugin.so randomize_layout_plugin.c 16 * $ gcc -fplugin=./randomize_layout_plugin.so test.c -O2 17 */ 18 19 #include "gcc-common.h" 20 #include "randomize_layout_seed.h" 21 22 #if BUILDING_GCC_MAJOR < 4 || (BUILDING_GCC_MAJOR == 4 && BUILDING_GCC_MINOR < 7) 23 #error "The RANDSTRUCT plugin requires GCC 4.7 or newer." 24 #endif 25 26 #define ORIG_TYPE_NAME(node) \ 27 (TYPE_NAME(TYPE_MAIN_VARIANT(node)) != NULL_TREE ? ((const unsigned char *)IDENTIFIER_POINTER(TYPE_NAME(TYPE_MAIN_VARIANT(node)))) : (const unsigned char *)"anonymous") 28 29 #define INFORM(loc, msg, ...) inform(loc, "randstruct: " msg, ##__VA_ARGS__) 30 #define MISMATCH(loc, how, ...) INFORM(loc, "casting between randomized structure pointer types (" how "): %qT and %qT\n", __VA_ARGS__) 31 32 __visible int plugin_is_GPL_compatible; 33 34 static int performance_mode; 35 36 static struct plugin_info randomize_layout_plugin_info = { 37 .version = "201402201816vanilla", 38 .help = "disable\t\t\tdo not activate plugin\n" 39 "performance-mode\tenable cacheline-aware layout randomization\n" 40 }; 41 42 struct whitelist_entry { 43 const char *pathname; 44 const char *lhs; 45 const char *rhs; 46 }; 47 48 static const struct whitelist_entry whitelist[] = { 49 { } 50 }; 51 52 /* from old Linux dcache.h */ 53 static inline unsigned long 54 partial_name_hash(unsigned long c, unsigned long prevhash) 55 { 56 return (prevhash + (c << 4) + (c >> 4)) * 11; 57 } 58 static inline unsigned int 59 name_hash(const unsigned char *name) 60 { 61 unsigned long hash = 0; 62 unsigned int len = strlen((const char *)name); 63 while (len--) 64 hash = partial_name_hash(*name++, hash); 65 return (unsigned int)hash; 66 } 67 68 static tree handle_randomize_layout_attr(tree *node, tree name, tree args, int flags, bool *no_add_attrs) 69 { 70 tree type; 71 72 *no_add_attrs = true; 73 if (TREE_CODE(*node) == FUNCTION_DECL) { 74 error("%qE attribute does not apply to functions (%qF)", name, *node); 75 return NULL_TREE; 76 } 77 78 if (TREE_CODE(*node) == PARM_DECL) { 79 error("%qE attribute does not apply to function parameters (%qD)", name, *node); 80 return NULL_TREE; 81 } 82 83 if (TREE_CODE(*node) == VAR_DECL) { 84 error("%qE attribute does not apply to variables (%qD)", name, *node); 85 return NULL_TREE; 86 } 87 88 if (TYPE_P(*node)) { 89 type = *node; 90 } else { 91 gcc_assert(TREE_CODE(*node) == TYPE_DECL); 92 type = TREE_TYPE(*node); 93 } 94 95 if (TREE_CODE(type) != RECORD_TYPE) { 96 error("%qE attribute used on %qT applies to struct types only", name, type); 97 return NULL_TREE; 98 } 99 100 if (lookup_attribute(IDENTIFIER_POINTER(name), TYPE_ATTRIBUTES(type))) { 101 error("%qE attribute is already applied to the type %qT", name, type); 102 return NULL_TREE; 103 } 104 105 *no_add_attrs = false; 106 107 return NULL_TREE; 108 } 109 110 /* set on complete types that we don't need to inspect further at all */ 111 static tree handle_randomize_considered_attr(tree *node, tree name, tree args, int flags, bool *no_add_attrs) 112 { 113 *no_add_attrs = false; 114 return NULL_TREE; 115 } 116 117 /* 118 * set on types that we've performed a shuffle on, to prevent re-shuffling 119 * this does not preclude us from inspecting its fields for potential shuffles 120 */ 121 static tree handle_randomize_performed_attr(tree *node, tree name, tree args, int flags, bool *no_add_attrs) 122 { 123 *no_add_attrs = false; 124 return NULL_TREE; 125 } 126 127 /* 128 * 64bit variant of Bob Jenkins' public domain PRNG 129 * 256 bits of internal state 130 */ 131 132 typedef unsigned long long u64; 133 134 typedef struct ranctx { u64 a; u64 b; u64 c; u64 d; } ranctx; 135 136 #define rot(x,k) (((x)<<(k))|((x)>>(64-(k)))) 137 static u64 ranval(ranctx *x) { 138 u64 e = x->a - rot(x->b, 7); 139 x->a = x->b ^ rot(x->c, 13); 140 x->b = x->c + rot(x->d, 37); 141 x->c = x->d + e; 142 x->d = e + x->a; 143 return x->d; 144 } 145 146 static void raninit(ranctx *x, u64 *seed) { 147 int i; 148 149 x->a = seed[0]; 150 x->b = seed[1]; 151 x->c = seed[2]; 152 x->d = seed[3]; 153 154 for (i=0; i < 30; ++i) 155 (void)ranval(x); 156 } 157 158 static u64 shuffle_seed[4]; 159 160 struct partition_group { 161 tree tree_start; 162 unsigned long start; 163 unsigned long length; 164 }; 165 166 static void partition_struct(tree *fields, unsigned long length, struct partition_group *size_groups, unsigned long *num_groups) 167 { 168 unsigned long i; 169 unsigned long accum_size = 0; 170 unsigned long accum_length = 0; 171 unsigned long group_idx = 0; 172 173 gcc_assert(length < INT_MAX); 174 175 memset(size_groups, 0, sizeof(struct partition_group) * length); 176 177 for (i = 0; i < length; i++) { 178 if (size_groups[group_idx].tree_start == NULL_TREE) { 179 size_groups[group_idx].tree_start = fields[i]; 180 size_groups[group_idx].start = i; 181 accum_length = 0; 182 accum_size = 0; 183 } 184 accum_size += (unsigned long)int_size_in_bytes(TREE_TYPE(fields[i])); 185 accum_length++; 186 if (accum_size >= 64) { 187 size_groups[group_idx].length = accum_length; 188 accum_length = 0; 189 group_idx++; 190 } 191 } 192 193 if (size_groups[group_idx].tree_start != NULL_TREE && 194 !size_groups[group_idx].length) { 195 size_groups[group_idx].length = accum_length; 196 group_idx++; 197 } 198 199 *num_groups = group_idx; 200 } 201 202 static void performance_shuffle(tree *newtree, unsigned long length, ranctx *prng_state) 203 { 204 unsigned long i, x; 205 struct partition_group size_group[length]; 206 unsigned long num_groups = 0; 207 unsigned long randnum; 208 209 partition_struct(newtree, length, (struct partition_group *)&size_group, &num_groups); 210 for (i = num_groups - 1; i > 0; i--) { 211 struct partition_group tmp; 212 randnum = ranval(prng_state) % (i + 1); 213 tmp = size_group[i]; 214 size_group[i] = size_group[randnum]; 215 size_group[randnum] = tmp; 216 } 217 218 for (x = 0; x < num_groups; x++) { 219 for (i = size_group[x].start + size_group[x].length - 1; i > size_group[x].start; i--) { 220 tree tmp; 221 if (DECL_BIT_FIELD_TYPE(newtree[i])) 222 continue; 223 randnum = ranval(prng_state) % (i + 1); 224 // we could handle this case differently if desired 225 if (DECL_BIT_FIELD_TYPE(newtree[randnum])) 226 continue; 227 tmp = newtree[i]; 228 newtree[i] = newtree[randnum]; 229 newtree[randnum] = tmp; 230 } 231 } 232 } 233 234 static void full_shuffle(tree *newtree, unsigned long length, ranctx *prng_state) 235 { 236 unsigned long i, randnum; 237 238 for (i = length - 1; i > 0; i--) { 239 tree tmp; 240 randnum = ranval(prng_state) % (i + 1); 241 tmp = newtree[i]; 242 newtree[i] = newtree[randnum]; 243 newtree[randnum] = tmp; 244 } 245 } 246 247 /* modern in-place Fisher-Yates shuffle */ 248 static void shuffle(const_tree type, tree *newtree, unsigned long length) 249 { 250 unsigned long i; 251 u64 seed[4]; 252 ranctx prng_state; 253 const unsigned char *structname; 254 255 if (length == 0) 256 return; 257 258 gcc_assert(TREE_CODE(type) == RECORD_TYPE); 259 260 structname = ORIG_TYPE_NAME(type); 261 262 #ifdef __DEBUG_PLUGIN 263 fprintf(stderr, "Shuffling struct %s %p\n", (const char *)structname, type); 264 #ifdef __DEBUG_VERBOSE 265 debug_tree((tree)type); 266 #endif 267 #endif 268 269 for (i = 0; i < 4; i++) { 270 seed[i] = shuffle_seed[i]; 271 seed[i] ^= name_hash(structname); 272 } 273 274 raninit(&prng_state, (u64 *)&seed); 275 276 if (performance_mode) 277 performance_shuffle(newtree, length, &prng_state); 278 else 279 full_shuffle(newtree, length, &prng_state); 280 } 281 282 static bool is_flexible_array(const_tree field) 283 { 284 const_tree fieldtype; 285 const_tree typesize; 286 const_tree elemtype; 287 const_tree elemsize; 288 289 fieldtype = TREE_TYPE(field); 290 typesize = TYPE_SIZE(fieldtype); 291 292 if (TREE_CODE(fieldtype) != ARRAY_TYPE) 293 return false; 294 295 elemtype = TREE_TYPE(fieldtype); 296 elemsize = TYPE_SIZE(elemtype); 297 298 /* size of type is represented in bits */ 299 300 if (typesize == NULL_TREE && TYPE_DOMAIN(fieldtype) != NULL_TREE && 301 TYPE_MAX_VALUE(TYPE_DOMAIN(fieldtype)) == NULL_TREE) 302 return true; 303 304 if (typesize != NULL_TREE && 305 (TREE_CONSTANT(typesize) && (!tree_to_uhwi(typesize) || 306 tree_to_uhwi(typesize) == tree_to_uhwi(elemsize)))) 307 return true; 308 309 return false; 310 } 311 312 static int relayout_struct(tree type) 313 { 314 unsigned long num_fields = (unsigned long)list_length(TYPE_FIELDS(type)); 315 unsigned long shuffle_length = num_fields; 316 tree field; 317 tree newtree[num_fields]; 318 unsigned long i; 319 tree list; 320 tree variant; 321 tree main_variant; 322 expanded_location xloc; 323 bool has_flexarray = false; 324 325 if (TYPE_FIELDS(type) == NULL_TREE) 326 return 0; 327 328 if (num_fields < 2) 329 return 0; 330 331 gcc_assert(TREE_CODE(type) == RECORD_TYPE); 332 333 gcc_assert(num_fields < INT_MAX); 334 335 if (lookup_attribute("randomize_performed", TYPE_ATTRIBUTES(type)) || 336 lookup_attribute("no_randomize_layout", TYPE_ATTRIBUTES(TYPE_MAIN_VARIANT(type)))) 337 return 0; 338 339 /* Workaround for 3rd-party VirtualBox source that we can't modify ourselves */ 340 if (!strcmp((const char *)ORIG_TYPE_NAME(type), "INTNETTRUNKFACTORY") || 341 !strcmp((const char *)ORIG_TYPE_NAME(type), "RAWPCIFACTORY")) 342 return 0; 343 344 /* throw out any structs in uapi */ 345 xloc = expand_location(DECL_SOURCE_LOCATION(TYPE_FIELDS(type))); 346 347 if (strstr(xloc.file, "/uapi/")) 348 error(G_("attempted to randomize userland API struct %s"), ORIG_TYPE_NAME(type)); 349 350 for (field = TYPE_FIELDS(type), i = 0; field; field = TREE_CHAIN(field), i++) { 351 gcc_assert(TREE_CODE(field) == FIELD_DECL); 352 newtree[i] = field; 353 } 354 355 /* 356 * enforce that we don't randomize the layout of the last 357 * element of a struct if it's a 0 or 1-length array 358 * or a proper flexible array 359 */ 360 if (is_flexible_array(newtree[num_fields - 1])) { 361 has_flexarray = true; 362 shuffle_length--; 363 } 364 365 shuffle(type, (tree *)newtree, shuffle_length); 366 367 /* 368 * set up a bogus anonymous struct field designed to error out on unnamed struct initializers 369 * as gcc provides no other way to detect such code 370 */ 371 list = make_node(FIELD_DECL); 372 TREE_CHAIN(list) = newtree[0]; 373 TREE_TYPE(list) = void_type_node; 374 DECL_SIZE(list) = bitsize_zero_node; 375 DECL_NONADDRESSABLE_P(list) = 1; 376 DECL_FIELD_BIT_OFFSET(list) = bitsize_zero_node; 377 DECL_SIZE_UNIT(list) = size_zero_node; 378 DECL_FIELD_OFFSET(list) = size_zero_node; 379 DECL_CONTEXT(list) = type; 380 // to satisfy the constify plugin 381 TREE_READONLY(list) = 1; 382 383 for (i = 0; i < num_fields - 1; i++) 384 TREE_CHAIN(newtree[i]) = newtree[i+1]; 385 TREE_CHAIN(newtree[num_fields - 1]) = NULL_TREE; 386 387 main_variant = TYPE_MAIN_VARIANT(type); 388 for (variant = main_variant; variant; variant = TYPE_NEXT_VARIANT(variant)) { 389 TYPE_FIELDS(variant) = list; 390 TYPE_ATTRIBUTES(variant) = copy_list(TYPE_ATTRIBUTES(variant)); 391 TYPE_ATTRIBUTES(variant) = tree_cons(get_identifier("randomize_performed"), NULL_TREE, TYPE_ATTRIBUTES(variant)); 392 TYPE_ATTRIBUTES(variant) = tree_cons(get_identifier("designated_init"), NULL_TREE, TYPE_ATTRIBUTES(variant)); 393 if (has_flexarray) 394 TYPE_ATTRIBUTES(type) = tree_cons(get_identifier("has_flexarray"), NULL_TREE, TYPE_ATTRIBUTES(type)); 395 } 396 397 /* 398 * force a re-layout of the main variant 399 * the TYPE_SIZE for all variants will be recomputed 400 * by finalize_type_size() 401 */ 402 TYPE_SIZE(main_variant) = NULL_TREE; 403 layout_type(main_variant); 404 gcc_assert(TYPE_SIZE(main_variant) != NULL_TREE); 405 406 return 1; 407 } 408 409 /* from constify plugin */ 410 static const_tree get_field_type(const_tree field) 411 { 412 return strip_array_types(TREE_TYPE(field)); 413 } 414 415 /* from constify plugin */ 416 static bool is_fptr(const_tree fieldtype) 417 { 418 if (TREE_CODE(fieldtype) != POINTER_TYPE) 419 return false; 420 421 return TREE_CODE(TREE_TYPE(fieldtype)) == FUNCTION_TYPE; 422 } 423 424 /* derived from constify plugin */ 425 static int is_pure_ops_struct(const_tree node) 426 { 427 const_tree field; 428 429 gcc_assert(TREE_CODE(node) == RECORD_TYPE || TREE_CODE(node) == UNION_TYPE); 430 431 /* XXX: Do not apply randomization to all-ftpr structs yet. */ 432 return 0; 433 434 for (field = TYPE_FIELDS(node); field; field = TREE_CHAIN(field)) { 435 const_tree fieldtype = get_field_type(field); 436 enum tree_code code = TREE_CODE(fieldtype); 437 438 if (node == fieldtype) 439 continue; 440 441 if (!is_fptr(fieldtype)) 442 return 0; 443 444 if (code != RECORD_TYPE && code != UNION_TYPE) 445 continue; 446 447 if (!is_pure_ops_struct(fieldtype)) 448 return 0; 449 } 450 451 return 1; 452 } 453 454 static void randomize_type(tree type) 455 { 456 tree variant; 457 458 gcc_assert(TREE_CODE(type) == RECORD_TYPE); 459 460 if (lookup_attribute("randomize_considered", TYPE_ATTRIBUTES(type))) 461 return; 462 463 if (lookup_attribute("randomize_layout", TYPE_ATTRIBUTES(TYPE_MAIN_VARIANT(type))) || is_pure_ops_struct(type)) 464 relayout_struct(type); 465 466 for (variant = TYPE_MAIN_VARIANT(type); variant; variant = TYPE_NEXT_VARIANT(variant)) { 467 TYPE_ATTRIBUTES(type) = copy_list(TYPE_ATTRIBUTES(type)); 468 TYPE_ATTRIBUTES(type) = tree_cons(get_identifier("randomize_considered"), NULL_TREE, TYPE_ATTRIBUTES(type)); 469 } 470 #ifdef __DEBUG_PLUGIN 471 fprintf(stderr, "Marking randomize_considered on struct %s\n", ORIG_TYPE_NAME(type)); 472 #ifdef __DEBUG_VERBOSE 473 debug_tree(type); 474 #endif 475 #endif 476 } 477 478 static void update_decl_size(tree decl) 479 { 480 tree lastval, lastidx, field, init, type, flexsize; 481 unsigned HOST_WIDE_INT len; 482 483 type = TREE_TYPE(decl); 484 485 if (!lookup_attribute("has_flexarray", TYPE_ATTRIBUTES(type))) 486 return; 487 488 init = DECL_INITIAL(decl); 489 if (init == NULL_TREE || init == error_mark_node) 490 return; 491 492 if (TREE_CODE(init) != CONSTRUCTOR) 493 return; 494 495 len = CONSTRUCTOR_NELTS(init); 496 if (!len) 497 return; 498 499 lastval = CONSTRUCTOR_ELT(init, CONSTRUCTOR_NELTS(init) - 1)->value; 500 lastidx = CONSTRUCTOR_ELT(init, CONSTRUCTOR_NELTS(init) - 1)->index; 501 502 for (field = TYPE_FIELDS(TREE_TYPE(decl)); TREE_CHAIN(field); field = TREE_CHAIN(field)) 503 ; 504 505 if (lastidx != field) 506 return; 507 508 if (TREE_CODE(lastval) != STRING_CST) { 509 error("Only string constants are supported as initializers " 510 "for randomized structures with flexible arrays"); 511 return; 512 } 513 514 flexsize = bitsize_int(TREE_STRING_LENGTH(lastval) * 515 tree_to_uhwi(TYPE_SIZE(TREE_TYPE(TREE_TYPE(lastval))))); 516 517 DECL_SIZE(decl) = size_binop(PLUS_EXPR, TYPE_SIZE(type), flexsize); 518 519 return; 520 } 521 522 523 static void randomize_layout_finish_decl(void *event_data, void *data) 524 { 525 tree decl = (tree)event_data; 526 tree type; 527 528 if (decl == NULL_TREE || decl == error_mark_node) 529 return; 530 531 type = TREE_TYPE(decl); 532 533 if (TREE_CODE(decl) != VAR_DECL) 534 return; 535 536 if (TREE_CODE(type) != RECORD_TYPE && TREE_CODE(type) != UNION_TYPE) 537 return; 538 539 if (!lookup_attribute("randomize_performed", TYPE_ATTRIBUTES(type))) 540 return; 541 542 DECL_SIZE(decl) = 0; 543 DECL_SIZE_UNIT(decl) = 0; 544 SET_DECL_ALIGN(decl, 0); 545 SET_DECL_MODE (decl, VOIDmode); 546 SET_DECL_RTL(decl, 0); 547 update_decl_size(decl); 548 layout_decl(decl, 0); 549 } 550 551 static void finish_type(void *event_data, void *data) 552 { 553 tree type = (tree)event_data; 554 555 if (type == NULL_TREE || type == error_mark_node) 556 return; 557 558 if (TREE_CODE(type) != RECORD_TYPE) 559 return; 560 561 if (TYPE_FIELDS(type) == NULL_TREE) 562 return; 563 564 if (lookup_attribute("randomize_considered", TYPE_ATTRIBUTES(type))) 565 return; 566 567 #ifdef __DEBUG_PLUGIN 568 fprintf(stderr, "Calling randomize_type on %s\n", ORIG_TYPE_NAME(type)); 569 #endif 570 #ifdef __DEBUG_VERBOSE 571 debug_tree(type); 572 #endif 573 randomize_type(type); 574 575 return; 576 } 577 578 static struct attribute_spec randomize_layout_attr = { 579 .name = "randomize_layout", 580 // related to args 581 .min_length = 0, 582 .max_length = 0, 583 .decl_required = false, 584 // need type declaration 585 .type_required = true, 586 .function_type_required = false, 587 .handler = handle_randomize_layout_attr, 588 #if BUILDING_GCC_VERSION >= 4007 589 .affects_type_identity = true 590 #endif 591 }; 592 593 static struct attribute_spec no_randomize_layout_attr = { 594 .name = "no_randomize_layout", 595 // related to args 596 .min_length = 0, 597 .max_length = 0, 598 .decl_required = false, 599 // need type declaration 600 .type_required = true, 601 .function_type_required = false, 602 .handler = handle_randomize_layout_attr, 603 #if BUILDING_GCC_VERSION >= 4007 604 .affects_type_identity = true 605 #endif 606 }; 607 608 static struct attribute_spec randomize_considered_attr = { 609 .name = "randomize_considered", 610 // related to args 611 .min_length = 0, 612 .max_length = 0, 613 .decl_required = false, 614 // need type declaration 615 .type_required = true, 616 .function_type_required = false, 617 .handler = handle_randomize_considered_attr, 618 #if BUILDING_GCC_VERSION >= 4007 619 .affects_type_identity = false 620 #endif 621 }; 622 623 static struct attribute_spec randomize_performed_attr = { 624 .name = "randomize_performed", 625 // related to args 626 .min_length = 0, 627 .max_length = 0, 628 .decl_required = false, 629 // need type declaration 630 .type_required = true, 631 .function_type_required = false, 632 .handler = handle_randomize_performed_attr, 633 #if BUILDING_GCC_VERSION >= 4007 634 .affects_type_identity = false 635 #endif 636 }; 637 638 static void register_attributes(void *event_data, void *data) 639 { 640 register_attribute(&randomize_layout_attr); 641 register_attribute(&no_randomize_layout_attr); 642 register_attribute(&randomize_considered_attr); 643 register_attribute(&randomize_performed_attr); 644 } 645 646 static void check_bad_casts_in_constructor(tree var, tree init) 647 { 648 unsigned HOST_WIDE_INT idx; 649 tree field, val; 650 tree field_type, val_type; 651 652 FOR_EACH_CONSTRUCTOR_ELT(CONSTRUCTOR_ELTS(init), idx, field, val) { 653 if (TREE_CODE(val) == CONSTRUCTOR) { 654 check_bad_casts_in_constructor(var, val); 655 continue; 656 } 657 658 /* pipacs' plugin creates franken-arrays that differ from those produced by 659 normal code which all have valid 'field' trees. work around this */ 660 if (field == NULL_TREE) 661 continue; 662 field_type = TREE_TYPE(field); 663 val_type = TREE_TYPE(val); 664 665 if (TREE_CODE(field_type) != POINTER_TYPE || TREE_CODE(val_type) != POINTER_TYPE) 666 continue; 667 668 if (field_type == val_type) 669 continue; 670 671 field_type = TYPE_MAIN_VARIANT(strip_array_types(TYPE_MAIN_VARIANT(TREE_TYPE(field_type)))); 672 val_type = TYPE_MAIN_VARIANT(strip_array_types(TYPE_MAIN_VARIANT(TREE_TYPE(val_type)))); 673 674 if (field_type == void_type_node) 675 continue; 676 if (field_type == val_type) 677 continue; 678 if (TREE_CODE(val_type) != RECORD_TYPE) 679 continue; 680 681 if (!lookup_attribute("randomize_performed", TYPE_ATTRIBUTES(val_type))) 682 continue; 683 MISMATCH(DECL_SOURCE_LOCATION(var), "constructor\n", TYPE_MAIN_VARIANT(field_type), TYPE_MAIN_VARIANT(val_type)); 684 } 685 } 686 687 /* derived from the constify plugin */ 688 static void check_global_variables(void *event_data, void *data) 689 { 690 struct varpool_node *node; 691 tree init; 692 693 FOR_EACH_VARIABLE(node) { 694 tree var = NODE_DECL(node); 695 init = DECL_INITIAL(var); 696 if (init == NULL_TREE) 697 continue; 698 699 if (TREE_CODE(init) != CONSTRUCTOR) 700 continue; 701 702 check_bad_casts_in_constructor(var, init); 703 } 704 } 705 706 static bool dominated_by_is_err(const_tree rhs, basic_block bb) 707 { 708 basic_block dom; 709 gimple dom_stmt; 710 gimple call_stmt; 711 const_tree dom_lhs; 712 const_tree poss_is_err_cond; 713 const_tree poss_is_err_func; 714 const_tree is_err_arg; 715 716 dom = get_immediate_dominator(CDI_DOMINATORS, bb); 717 if (!dom) 718 return false; 719 720 dom_stmt = last_stmt(dom); 721 if (!dom_stmt) 722 return false; 723 724 if (gimple_code(dom_stmt) != GIMPLE_COND) 725 return false; 726 727 if (gimple_cond_code(dom_stmt) != NE_EXPR) 728 return false; 729 730 if (!integer_zerop(gimple_cond_rhs(dom_stmt))) 731 return false; 732 733 poss_is_err_cond = gimple_cond_lhs(dom_stmt); 734 735 if (TREE_CODE(poss_is_err_cond) != SSA_NAME) 736 return false; 737 738 call_stmt = SSA_NAME_DEF_STMT(poss_is_err_cond); 739 740 if (gimple_code(call_stmt) != GIMPLE_CALL) 741 return false; 742 743 dom_lhs = gimple_get_lhs(call_stmt); 744 poss_is_err_func = gimple_call_fndecl(call_stmt); 745 if (!poss_is_err_func) 746 return false; 747 if (dom_lhs != poss_is_err_cond) 748 return false; 749 if (strcmp(DECL_NAME_POINTER(poss_is_err_func), "IS_ERR")) 750 return false; 751 752 is_err_arg = gimple_call_arg(call_stmt, 0); 753 if (!is_err_arg) 754 return false; 755 756 if (is_err_arg != rhs) 757 return false; 758 759 return true; 760 } 761 762 static void handle_local_var_initializers(void) 763 { 764 tree var; 765 unsigned int i; 766 767 FOR_EACH_LOCAL_DECL(cfun, i, var) { 768 tree init = DECL_INITIAL(var); 769 if (!init) 770 continue; 771 if (TREE_CODE(init) != CONSTRUCTOR) 772 continue; 773 check_bad_casts_in_constructor(var, init); 774 } 775 } 776 777 static bool type_name_eq(gimple stmt, const_tree type_tree, const char *wanted_name) 778 { 779 const char *type_name; 780 781 if (type_tree == NULL_TREE) 782 return false; 783 784 switch (TREE_CODE(type_tree)) { 785 case RECORD_TYPE: 786 type_name = TYPE_NAME_POINTER(type_tree); 787 break; 788 case INTEGER_TYPE: 789 if (TYPE_PRECISION(type_tree) == CHAR_TYPE_SIZE) 790 type_name = "char"; 791 else { 792 INFORM(gimple_location(stmt), "found non-char INTEGER_TYPE cast comparison: %qT\n", type_tree); 793 debug_tree(type_tree); 794 return false; 795 } 796 break; 797 case POINTER_TYPE: 798 if (TREE_CODE(TREE_TYPE(type_tree)) == VOID_TYPE) { 799 type_name = "void *"; 800 break; 801 } else { 802 INFORM(gimple_location(stmt), "found non-void POINTER_TYPE cast comparison %qT\n", type_tree); 803 debug_tree(type_tree); 804 return false; 805 } 806 default: 807 INFORM(gimple_location(stmt), "unhandled cast comparison: %qT\n", type_tree); 808 debug_tree(type_tree); 809 return false; 810 } 811 812 return strcmp(type_name, wanted_name) == 0; 813 } 814 815 static bool whitelisted_cast(gimple stmt, const_tree lhs_tree, const_tree rhs_tree) 816 { 817 const struct whitelist_entry *entry; 818 expanded_location xloc = expand_location(gimple_location(stmt)); 819 820 for (entry = whitelist; entry->pathname; entry++) { 821 if (!strstr(xloc.file, entry->pathname)) 822 continue; 823 824 if (type_name_eq(stmt, lhs_tree, entry->lhs) && type_name_eq(stmt, rhs_tree, entry->rhs)) 825 return true; 826 } 827 828 return false; 829 } 830 831 /* 832 * iterate over all statements to find "bad" casts: 833 * those where the address of the start of a structure is cast 834 * to a pointer of a structure of a different type, or a 835 * structure pointer type is cast to a different structure pointer type 836 */ 837 static unsigned int find_bad_casts_execute(void) 838 { 839 basic_block bb; 840 841 handle_local_var_initializers(); 842 843 FOR_EACH_BB_FN(bb, cfun) { 844 gimple_stmt_iterator gsi; 845 846 for (gsi = gsi_start_bb(bb); !gsi_end_p(gsi); gsi_next(&gsi)) { 847 gimple stmt; 848 const_tree lhs; 849 const_tree lhs_type; 850 const_tree rhs1; 851 const_tree rhs_type; 852 const_tree ptr_lhs_type; 853 const_tree ptr_rhs_type; 854 const_tree op0; 855 const_tree op0_type; 856 enum tree_code rhs_code; 857 858 stmt = gsi_stmt(gsi); 859 860 #ifdef __DEBUG_PLUGIN 861 #ifdef __DEBUG_VERBOSE 862 debug_gimple_stmt(stmt); 863 debug_tree(gimple_get_lhs(stmt)); 864 #endif 865 #endif 866 867 if (gimple_code(stmt) != GIMPLE_ASSIGN) 868 continue; 869 870 #ifdef __DEBUG_PLUGIN 871 #ifdef __DEBUG_VERBOSE 872 debug_tree(gimple_assign_rhs1(stmt)); 873 #endif 874 #endif 875 876 877 rhs_code = gimple_assign_rhs_code(stmt); 878 879 if (rhs_code != ADDR_EXPR && rhs_code != SSA_NAME) 880 continue; 881 882 lhs = gimple_get_lhs(stmt); 883 lhs_type = TREE_TYPE(lhs); 884 rhs1 = gimple_assign_rhs1(stmt); 885 rhs_type = TREE_TYPE(rhs1); 886 887 if (TREE_CODE(rhs_type) != POINTER_TYPE || 888 TREE_CODE(lhs_type) != POINTER_TYPE) 889 continue; 890 891 ptr_lhs_type = TYPE_MAIN_VARIANT(strip_array_types(TYPE_MAIN_VARIANT(TREE_TYPE(lhs_type)))); 892 ptr_rhs_type = TYPE_MAIN_VARIANT(strip_array_types(TYPE_MAIN_VARIANT(TREE_TYPE(rhs_type)))); 893 894 if (ptr_rhs_type == void_type_node) 895 continue; 896 897 if (ptr_lhs_type == void_type_node) 898 continue; 899 900 if (dominated_by_is_err(rhs1, bb)) 901 continue; 902 903 if (TREE_CODE(ptr_rhs_type) != RECORD_TYPE) { 904 #ifndef __DEBUG_PLUGIN 905 if (lookup_attribute("randomize_performed", TYPE_ATTRIBUTES(ptr_lhs_type))) 906 #endif 907 { 908 if (!whitelisted_cast(stmt, ptr_lhs_type, ptr_rhs_type)) 909 MISMATCH(gimple_location(stmt), "rhs", ptr_lhs_type, ptr_rhs_type); 910 } 911 continue; 912 } 913 914 if (rhs_code == SSA_NAME && ptr_lhs_type == ptr_rhs_type) 915 continue; 916 917 if (rhs_code == ADDR_EXPR) { 918 op0 = TREE_OPERAND(rhs1, 0); 919 920 if (op0 == NULL_TREE) 921 continue; 922 923 if (TREE_CODE(op0) != VAR_DECL) 924 continue; 925 926 op0_type = TYPE_MAIN_VARIANT(strip_array_types(TYPE_MAIN_VARIANT(TREE_TYPE(op0)))); 927 if (op0_type == ptr_lhs_type) 928 continue; 929 930 #ifndef __DEBUG_PLUGIN 931 if (lookup_attribute("randomize_performed", TYPE_ATTRIBUTES(op0_type))) 932 #endif 933 { 934 if (!whitelisted_cast(stmt, ptr_lhs_type, op0_type)) 935 MISMATCH(gimple_location(stmt), "op0", ptr_lhs_type, op0_type); 936 } 937 } else { 938 const_tree ssa_name_var = SSA_NAME_VAR(rhs1); 939 /* skip bogus type casts introduced by container_of */ 940 if (ssa_name_var != NULL_TREE && DECL_NAME(ssa_name_var) && 941 !strcmp((const char *)DECL_NAME_POINTER(ssa_name_var), "__mptr")) 942 continue; 943 #ifndef __DEBUG_PLUGIN 944 if (lookup_attribute("randomize_performed", TYPE_ATTRIBUTES(ptr_rhs_type))) 945 #endif 946 { 947 if (!whitelisted_cast(stmt, ptr_lhs_type, ptr_rhs_type)) 948 MISMATCH(gimple_location(stmt), "ssa", ptr_lhs_type, ptr_rhs_type); 949 } 950 } 951 952 } 953 } 954 return 0; 955 } 956 957 #define PASS_NAME find_bad_casts 958 #define NO_GATE 959 #define TODO_FLAGS_FINISH TODO_dump_func 960 #include "gcc-generate-gimple-pass.h" 961 962 __visible int plugin_init(struct plugin_name_args *plugin_info, struct plugin_gcc_version *version) 963 { 964 int i; 965 const char * const plugin_name = plugin_info->base_name; 966 const int argc = plugin_info->argc; 967 const struct plugin_argument * const argv = plugin_info->argv; 968 bool enable = true; 969 int obtained_seed = 0; 970 struct register_pass_info find_bad_casts_pass_info; 971 972 find_bad_casts_pass_info.pass = make_find_bad_casts_pass(); 973 find_bad_casts_pass_info.reference_pass_name = "ssa"; 974 find_bad_casts_pass_info.ref_pass_instance_number = 1; 975 find_bad_casts_pass_info.pos_op = PASS_POS_INSERT_AFTER; 976 977 if (!plugin_default_version_check(version, &gcc_version)) { 978 error(G_("incompatible gcc/plugin versions")); 979 return 1; 980 } 981 982 if (strncmp(lang_hooks.name, "GNU C", 5) && !strncmp(lang_hooks.name, "GNU C+", 6)) { 983 inform(UNKNOWN_LOCATION, G_("%s supports C only, not %s"), plugin_name, lang_hooks.name); 984 enable = false; 985 } 986 987 for (i = 0; i < argc; ++i) { 988 if (!strcmp(argv[i].key, "disable")) { 989 enable = false; 990 continue; 991 } 992 if (!strcmp(argv[i].key, "performance-mode")) { 993 performance_mode = 1; 994 continue; 995 } 996 error(G_("unknown option '-fplugin-arg-%s-%s'"), plugin_name, argv[i].key); 997 } 998 999 if (strlen(randstruct_seed) != 64) { 1000 error(G_("invalid seed value supplied for %s plugin"), plugin_name); 1001 return 1; 1002 } 1003 obtained_seed = sscanf(randstruct_seed, "%016llx%016llx%016llx%016llx", 1004 &shuffle_seed[0], &shuffle_seed[1], &shuffle_seed[2], &shuffle_seed[3]); 1005 if (obtained_seed != 4) { 1006 error(G_("Invalid seed supplied for %s plugin"), plugin_name); 1007 return 1; 1008 } 1009 1010 register_callback(plugin_name, PLUGIN_INFO, NULL, &randomize_layout_plugin_info); 1011 if (enable) { 1012 register_callback(plugin_name, PLUGIN_ALL_IPA_PASSES_START, check_global_variables, NULL); 1013 register_callback(plugin_name, PLUGIN_PASS_MANAGER_SETUP, NULL, &find_bad_casts_pass_info); 1014 register_callback(plugin_name, PLUGIN_FINISH_TYPE, finish_type, NULL); 1015 register_callback(plugin_name, PLUGIN_FINISH_DECL, randomize_layout_finish_decl, NULL); 1016 } 1017 register_callback(plugin_name, PLUGIN_ATTRIBUTES, register_attributes, NULL); 1018 1019 return 0; 1020 } 1021