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