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