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