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 const_tree elemtype; 282 const_tree elemsize; 283 284 fieldtype = TREE_TYPE(field); 285 typesize = TYPE_SIZE(fieldtype); 286 287 if (TREE_CODE(fieldtype) != ARRAY_TYPE) 288 return false; 289 290 elemtype = TREE_TYPE(fieldtype); 291 elemsize = TYPE_SIZE(elemtype); 292 293 /* size of type is represented in bits */ 294 295 if (typesize == NULL_TREE && TYPE_DOMAIN(fieldtype) != NULL_TREE && 296 TYPE_MAX_VALUE(TYPE_DOMAIN(fieldtype)) == NULL_TREE) 297 return true; 298 299 if (typesize != NULL_TREE && 300 (TREE_CONSTANT(typesize) && (!tree_to_uhwi(typesize) || 301 tree_to_uhwi(typesize) == tree_to_uhwi(elemsize)))) 302 return true; 303 304 return false; 305 } 306 307 static int relayout_struct(tree type) 308 { 309 unsigned long num_fields = (unsigned long)list_length(TYPE_FIELDS(type)); 310 unsigned long shuffle_length = num_fields; 311 tree field; 312 tree newtree[num_fields]; 313 unsigned long i; 314 tree list; 315 tree variant; 316 tree main_variant; 317 expanded_location xloc; 318 bool has_flexarray = false; 319 320 if (TYPE_FIELDS(type) == NULL_TREE) 321 return 0; 322 323 if (num_fields < 2) 324 return 0; 325 326 gcc_assert(TREE_CODE(type) == RECORD_TYPE); 327 328 gcc_assert(num_fields < INT_MAX); 329 330 if (lookup_attribute("randomize_performed", TYPE_ATTRIBUTES(type)) || 331 lookup_attribute("no_randomize_layout", TYPE_ATTRIBUTES(TYPE_MAIN_VARIANT(type)))) 332 return 0; 333 334 /* Workaround for 3rd-party VirtualBox source that we can't modify ourselves */ 335 if (!strcmp((const char *)ORIG_TYPE_NAME(type), "INTNETTRUNKFACTORY") || 336 !strcmp((const char *)ORIG_TYPE_NAME(type), "RAWPCIFACTORY")) 337 return 0; 338 339 /* throw out any structs in uapi */ 340 xloc = expand_location(DECL_SOURCE_LOCATION(TYPE_FIELDS(type))); 341 342 if (strstr(xloc.file, "/uapi/")) 343 error(G_("attempted to randomize userland API struct %s"), ORIG_TYPE_NAME(type)); 344 345 for (field = TYPE_FIELDS(type), i = 0; field; field = TREE_CHAIN(field), i++) { 346 gcc_assert(TREE_CODE(field) == FIELD_DECL); 347 newtree[i] = field; 348 } 349 350 /* 351 * enforce that we don't randomize the layout of the last 352 * element of a struct if it's a 0 or 1-length array 353 * or a proper flexible array 354 */ 355 if (is_flexible_array(newtree[num_fields - 1])) { 356 has_flexarray = true; 357 shuffle_length--; 358 } 359 360 shuffle(type, (tree *)newtree, shuffle_length); 361 362 /* 363 * set up a bogus anonymous struct field designed to error out on unnamed struct initializers 364 * as gcc provides no other way to detect such code 365 */ 366 list = make_node(FIELD_DECL); 367 TREE_CHAIN(list) = newtree[0]; 368 TREE_TYPE(list) = void_type_node; 369 DECL_SIZE(list) = bitsize_zero_node; 370 DECL_NONADDRESSABLE_P(list) = 1; 371 DECL_FIELD_BIT_OFFSET(list) = bitsize_zero_node; 372 DECL_SIZE_UNIT(list) = size_zero_node; 373 DECL_FIELD_OFFSET(list) = size_zero_node; 374 DECL_CONTEXT(list) = type; 375 // to satisfy the constify plugin 376 TREE_READONLY(list) = 1; 377 378 for (i = 0; i < num_fields - 1; i++) 379 TREE_CHAIN(newtree[i]) = newtree[i+1]; 380 TREE_CHAIN(newtree[num_fields - 1]) = NULL_TREE; 381 382 main_variant = TYPE_MAIN_VARIANT(type); 383 for (variant = main_variant; variant; variant = TYPE_NEXT_VARIANT(variant)) { 384 TYPE_FIELDS(variant) = list; 385 TYPE_ATTRIBUTES(variant) = copy_list(TYPE_ATTRIBUTES(variant)); 386 TYPE_ATTRIBUTES(variant) = tree_cons(get_identifier("randomize_performed"), NULL_TREE, TYPE_ATTRIBUTES(variant)); 387 TYPE_ATTRIBUTES(variant) = tree_cons(get_identifier("designated_init"), NULL_TREE, TYPE_ATTRIBUTES(variant)); 388 if (has_flexarray) 389 TYPE_ATTRIBUTES(type) = tree_cons(get_identifier("has_flexarray"), NULL_TREE, TYPE_ATTRIBUTES(type)); 390 } 391 392 /* 393 * force a re-layout of the main variant 394 * the TYPE_SIZE for all variants will be recomputed 395 * by finalize_type_size() 396 */ 397 TYPE_SIZE(main_variant) = NULL_TREE; 398 layout_type(main_variant); 399 gcc_assert(TYPE_SIZE(main_variant) != NULL_TREE); 400 401 return 1; 402 } 403 404 /* from constify plugin */ 405 static const_tree get_field_type(const_tree field) 406 { 407 return strip_array_types(TREE_TYPE(field)); 408 } 409 410 /* from constify plugin */ 411 static bool is_fptr(const_tree fieldtype) 412 { 413 if (TREE_CODE(fieldtype) != POINTER_TYPE) 414 return false; 415 416 return TREE_CODE(TREE_TYPE(fieldtype)) == FUNCTION_TYPE; 417 } 418 419 /* derived from constify plugin */ 420 static int is_pure_ops_struct(const_tree node) 421 { 422 const_tree field; 423 424 gcc_assert(TREE_CODE(node) == RECORD_TYPE || TREE_CODE(node) == UNION_TYPE); 425 426 for (field = TYPE_FIELDS(node); field; field = TREE_CHAIN(field)) { 427 const_tree fieldtype = get_field_type(field); 428 enum tree_code code = TREE_CODE(fieldtype); 429 430 if (node == fieldtype) 431 continue; 432 433 if (code == RECORD_TYPE || code == UNION_TYPE) { 434 if (!is_pure_ops_struct(fieldtype)) 435 return 0; 436 continue; 437 } 438 439 if (!is_fptr(fieldtype)) 440 return 0; 441 } 442 443 return 1; 444 } 445 446 static void randomize_type(tree type) 447 { 448 tree variant; 449 450 gcc_assert(TREE_CODE(type) == RECORD_TYPE); 451 452 if (lookup_attribute("randomize_considered", TYPE_ATTRIBUTES(type))) 453 return; 454 455 if (lookup_attribute("randomize_layout", TYPE_ATTRIBUTES(TYPE_MAIN_VARIANT(type))) || is_pure_ops_struct(type)) 456 relayout_struct(type); 457 458 for (variant = TYPE_MAIN_VARIANT(type); variant; variant = TYPE_NEXT_VARIANT(variant)) { 459 TYPE_ATTRIBUTES(type) = copy_list(TYPE_ATTRIBUTES(type)); 460 TYPE_ATTRIBUTES(type) = tree_cons(get_identifier("randomize_considered"), NULL_TREE, TYPE_ATTRIBUTES(type)); 461 } 462 #ifdef __DEBUG_PLUGIN 463 fprintf(stderr, "Marking randomize_considered on struct %s\n", ORIG_TYPE_NAME(type)); 464 #ifdef __DEBUG_VERBOSE 465 debug_tree(type); 466 #endif 467 #endif 468 } 469 470 static void update_decl_size(tree decl) 471 { 472 tree lastval, lastidx, field, init, type, flexsize; 473 unsigned HOST_WIDE_INT len; 474 475 type = TREE_TYPE(decl); 476 477 if (!lookup_attribute("has_flexarray", TYPE_ATTRIBUTES(type))) 478 return; 479 480 init = DECL_INITIAL(decl); 481 if (init == NULL_TREE || init == error_mark_node) 482 return; 483 484 if (TREE_CODE(init) != CONSTRUCTOR) 485 return; 486 487 len = CONSTRUCTOR_NELTS(init); 488 if (!len) 489 return; 490 491 lastval = CONSTRUCTOR_ELT(init, CONSTRUCTOR_NELTS(init) - 1)->value; 492 lastidx = CONSTRUCTOR_ELT(init, CONSTRUCTOR_NELTS(init) - 1)->index; 493 494 for (field = TYPE_FIELDS(TREE_TYPE(decl)); TREE_CHAIN(field); field = TREE_CHAIN(field)) 495 ; 496 497 if (lastidx != field) 498 return; 499 500 if (TREE_CODE(lastval) != STRING_CST) { 501 error("Only string constants are supported as initializers " 502 "for randomized structures with flexible arrays"); 503 return; 504 } 505 506 flexsize = bitsize_int(TREE_STRING_LENGTH(lastval) * 507 tree_to_uhwi(TYPE_SIZE(TREE_TYPE(TREE_TYPE(lastval))))); 508 509 DECL_SIZE(decl) = size_binop(PLUS_EXPR, TYPE_SIZE(type), flexsize); 510 511 return; 512 } 513 514 515 static void randomize_layout_finish_decl(void *event_data, void *data) 516 { 517 tree decl = (tree)event_data; 518 tree type; 519 520 if (decl == NULL_TREE || decl == error_mark_node) 521 return; 522 523 type = TREE_TYPE(decl); 524 525 if (TREE_CODE(decl) != VAR_DECL) 526 return; 527 528 if (TREE_CODE(type) != RECORD_TYPE && TREE_CODE(type) != UNION_TYPE) 529 return; 530 531 if (!lookup_attribute("randomize_performed", TYPE_ATTRIBUTES(type))) 532 return; 533 534 DECL_SIZE(decl) = 0; 535 DECL_SIZE_UNIT(decl) = 0; 536 SET_DECL_ALIGN(decl, 0); 537 SET_DECL_MODE (decl, VOIDmode); 538 SET_DECL_RTL(decl, 0); 539 update_decl_size(decl); 540 layout_decl(decl, 0); 541 } 542 543 static void finish_type(void *event_data, void *data) 544 { 545 tree type = (tree)event_data; 546 547 if (type == NULL_TREE || type == error_mark_node) 548 return; 549 550 if (TREE_CODE(type) != RECORD_TYPE) 551 return; 552 553 if (TYPE_FIELDS(type) == NULL_TREE) 554 return; 555 556 if (lookup_attribute("randomize_considered", TYPE_ATTRIBUTES(type))) 557 return; 558 559 #ifdef __DEBUG_PLUGIN 560 fprintf(stderr, "Calling randomize_type on %s\n", ORIG_TYPE_NAME(type)); 561 #endif 562 #ifdef __DEBUG_VERBOSE 563 debug_tree(type); 564 #endif 565 randomize_type(type); 566 567 return; 568 } 569 570 static struct attribute_spec randomize_layout_attr = { }; 571 static struct attribute_spec no_randomize_layout_attr = { }; 572 static struct attribute_spec randomize_considered_attr = { }; 573 static struct attribute_spec randomize_performed_attr = { }; 574 575 static void register_attributes(void *event_data, void *data) 576 { 577 randomize_layout_attr.name = "randomize_layout"; 578 randomize_layout_attr.type_required = true; 579 randomize_layout_attr.handler = handle_randomize_layout_attr; 580 randomize_layout_attr.affects_type_identity = true; 581 582 no_randomize_layout_attr.name = "no_randomize_layout"; 583 no_randomize_layout_attr.type_required = true; 584 no_randomize_layout_attr.handler = handle_randomize_layout_attr; 585 no_randomize_layout_attr.affects_type_identity = true; 586 587 randomize_considered_attr.name = "randomize_considered"; 588 randomize_considered_attr.type_required = true; 589 randomize_considered_attr.handler = handle_randomize_considered_attr; 590 591 randomize_performed_attr.name = "randomize_performed"; 592 randomize_performed_attr.type_required = true; 593 randomize_performed_attr.handler = handle_randomize_performed_attr; 594 595 register_attribute(&randomize_layout_attr); 596 register_attribute(&no_randomize_layout_attr); 597 register_attribute(&randomize_considered_attr); 598 register_attribute(&randomize_performed_attr); 599 } 600 601 static void check_bad_casts_in_constructor(tree var, tree init) 602 { 603 unsigned HOST_WIDE_INT idx; 604 tree field, val; 605 tree field_type, val_type; 606 607 FOR_EACH_CONSTRUCTOR_ELT(CONSTRUCTOR_ELTS(init), idx, field, val) { 608 if (TREE_CODE(val) == CONSTRUCTOR) { 609 check_bad_casts_in_constructor(var, val); 610 continue; 611 } 612 613 /* pipacs' plugin creates franken-arrays that differ from those produced by 614 normal code which all have valid 'field' trees. work around this */ 615 if (field == NULL_TREE) 616 continue; 617 field_type = TREE_TYPE(field); 618 val_type = TREE_TYPE(val); 619 620 if (TREE_CODE(field_type) != POINTER_TYPE || TREE_CODE(val_type) != POINTER_TYPE) 621 continue; 622 623 if (field_type == val_type) 624 continue; 625 626 field_type = TYPE_MAIN_VARIANT(strip_array_types(TYPE_MAIN_VARIANT(TREE_TYPE(field_type)))); 627 val_type = TYPE_MAIN_VARIANT(strip_array_types(TYPE_MAIN_VARIANT(TREE_TYPE(val_type)))); 628 629 if (field_type == void_type_node) 630 continue; 631 if (field_type == val_type) 632 continue; 633 if (TREE_CODE(val_type) != RECORD_TYPE) 634 continue; 635 636 if (!lookup_attribute("randomize_performed", TYPE_ATTRIBUTES(val_type))) 637 continue; 638 MISMATCH(DECL_SOURCE_LOCATION(var), "constructor\n", TYPE_MAIN_VARIANT(field_type), TYPE_MAIN_VARIANT(val_type)); 639 } 640 } 641 642 /* derived from the constify plugin */ 643 static void check_global_variables(void *event_data, void *data) 644 { 645 struct varpool_node *node; 646 tree init; 647 648 FOR_EACH_VARIABLE(node) { 649 tree var = NODE_DECL(node); 650 init = DECL_INITIAL(var); 651 if (init == NULL_TREE) 652 continue; 653 654 if (TREE_CODE(init) != CONSTRUCTOR) 655 continue; 656 657 check_bad_casts_in_constructor(var, init); 658 } 659 } 660 661 static bool dominated_by_is_err(const_tree rhs, basic_block bb) 662 { 663 basic_block dom; 664 gimple dom_stmt; 665 gimple call_stmt; 666 const_tree dom_lhs; 667 const_tree poss_is_err_cond; 668 const_tree poss_is_err_func; 669 const_tree is_err_arg; 670 671 dom = get_immediate_dominator(CDI_DOMINATORS, bb); 672 if (!dom) 673 return false; 674 675 dom_stmt = last_stmt(dom); 676 if (!dom_stmt) 677 return false; 678 679 if (gimple_code(dom_stmt) != GIMPLE_COND) 680 return false; 681 682 if (gimple_cond_code(dom_stmt) != NE_EXPR) 683 return false; 684 685 if (!integer_zerop(gimple_cond_rhs(dom_stmt))) 686 return false; 687 688 poss_is_err_cond = gimple_cond_lhs(dom_stmt); 689 690 if (TREE_CODE(poss_is_err_cond) != SSA_NAME) 691 return false; 692 693 call_stmt = SSA_NAME_DEF_STMT(poss_is_err_cond); 694 695 if (gimple_code(call_stmt) != GIMPLE_CALL) 696 return false; 697 698 dom_lhs = gimple_get_lhs(call_stmt); 699 poss_is_err_func = gimple_call_fndecl(call_stmt); 700 if (!poss_is_err_func) 701 return false; 702 if (dom_lhs != poss_is_err_cond) 703 return false; 704 if (strcmp(DECL_NAME_POINTER(poss_is_err_func), "IS_ERR")) 705 return false; 706 707 is_err_arg = gimple_call_arg(call_stmt, 0); 708 if (!is_err_arg) 709 return false; 710 711 if (is_err_arg != rhs) 712 return false; 713 714 return true; 715 } 716 717 static void handle_local_var_initializers(void) 718 { 719 tree var; 720 unsigned int i; 721 722 FOR_EACH_LOCAL_DECL(cfun, i, var) { 723 tree init = DECL_INITIAL(var); 724 if (!init) 725 continue; 726 if (TREE_CODE(init) != CONSTRUCTOR) 727 continue; 728 check_bad_casts_in_constructor(var, init); 729 } 730 } 731 732 /* 733 * iterate over all statements to find "bad" casts: 734 * those where the address of the start of a structure is cast 735 * to a pointer of a structure of a different type, or a 736 * structure pointer type is cast to a different structure pointer type 737 */ 738 static unsigned int find_bad_casts_execute(void) 739 { 740 basic_block bb; 741 742 handle_local_var_initializers(); 743 744 FOR_EACH_BB_FN(bb, cfun) { 745 gimple_stmt_iterator gsi; 746 747 for (gsi = gsi_start_bb(bb); !gsi_end_p(gsi); gsi_next(&gsi)) { 748 gimple stmt; 749 const_tree lhs; 750 const_tree lhs_type; 751 const_tree rhs1; 752 const_tree rhs_type; 753 const_tree ptr_lhs_type; 754 const_tree ptr_rhs_type; 755 const_tree op0; 756 const_tree op0_type; 757 enum tree_code rhs_code; 758 759 stmt = gsi_stmt(gsi); 760 761 #ifdef __DEBUG_PLUGIN 762 #ifdef __DEBUG_VERBOSE 763 debug_gimple_stmt(stmt); 764 debug_tree(gimple_get_lhs(stmt)); 765 #endif 766 #endif 767 768 if (gimple_code(stmt) != GIMPLE_ASSIGN) 769 continue; 770 771 #ifdef __DEBUG_PLUGIN 772 #ifdef __DEBUG_VERBOSE 773 debug_tree(gimple_assign_rhs1(stmt)); 774 #endif 775 #endif 776 777 778 rhs_code = gimple_assign_rhs_code(stmt); 779 780 if (rhs_code != ADDR_EXPR && rhs_code != SSA_NAME) 781 continue; 782 783 lhs = gimple_get_lhs(stmt); 784 lhs_type = TREE_TYPE(lhs); 785 rhs1 = gimple_assign_rhs1(stmt); 786 rhs_type = TREE_TYPE(rhs1); 787 788 if (TREE_CODE(rhs_type) != POINTER_TYPE || 789 TREE_CODE(lhs_type) != POINTER_TYPE) 790 continue; 791 792 ptr_lhs_type = TYPE_MAIN_VARIANT(strip_array_types(TYPE_MAIN_VARIANT(TREE_TYPE(lhs_type)))); 793 ptr_rhs_type = TYPE_MAIN_VARIANT(strip_array_types(TYPE_MAIN_VARIANT(TREE_TYPE(rhs_type)))); 794 795 if (ptr_rhs_type == void_type_node) 796 continue; 797 798 if (ptr_lhs_type == void_type_node) 799 continue; 800 801 if (dominated_by_is_err(rhs1, bb)) 802 continue; 803 804 if (TREE_CODE(ptr_rhs_type) != RECORD_TYPE) { 805 #ifndef __DEBUG_PLUGIN 806 if (lookup_attribute("randomize_performed", TYPE_ATTRIBUTES(ptr_lhs_type))) 807 #endif 808 MISMATCH(gimple_location(stmt), "rhs", ptr_lhs_type, ptr_rhs_type); 809 continue; 810 } 811 812 if (rhs_code == SSA_NAME && ptr_lhs_type == ptr_rhs_type) 813 continue; 814 815 if (rhs_code == ADDR_EXPR) { 816 op0 = TREE_OPERAND(rhs1, 0); 817 818 if (op0 == NULL_TREE) 819 continue; 820 821 if (TREE_CODE(op0) != VAR_DECL) 822 continue; 823 824 op0_type = TYPE_MAIN_VARIANT(strip_array_types(TYPE_MAIN_VARIANT(TREE_TYPE(op0)))); 825 if (op0_type == ptr_lhs_type) 826 continue; 827 828 #ifndef __DEBUG_PLUGIN 829 if (lookup_attribute("randomize_performed", TYPE_ATTRIBUTES(op0_type))) 830 #endif 831 MISMATCH(gimple_location(stmt), "op0", ptr_lhs_type, op0_type); 832 } else { 833 const_tree ssa_name_var = SSA_NAME_VAR(rhs1); 834 /* skip bogus type casts introduced by container_of */ 835 if (ssa_name_var != NULL_TREE && DECL_NAME(ssa_name_var) && 836 !strcmp((const char *)DECL_NAME_POINTER(ssa_name_var), "__mptr")) 837 continue; 838 #ifndef __DEBUG_PLUGIN 839 if (lookup_attribute("randomize_performed", TYPE_ATTRIBUTES(ptr_rhs_type))) 840 #endif 841 MISMATCH(gimple_location(stmt), "ssa", ptr_lhs_type, ptr_rhs_type); 842 } 843 844 } 845 } 846 return 0; 847 } 848 849 #define PASS_NAME find_bad_casts 850 #define NO_GATE 851 #define TODO_FLAGS_FINISH TODO_dump_func 852 #include "gcc-generate-gimple-pass.h" 853 854 __visible int plugin_init(struct plugin_name_args *plugin_info, struct plugin_gcc_version *version) 855 { 856 int i; 857 const char * const plugin_name = plugin_info->base_name; 858 const int argc = plugin_info->argc; 859 const struct plugin_argument * const argv = plugin_info->argv; 860 bool enable = true; 861 int obtained_seed = 0; 862 struct register_pass_info find_bad_casts_pass_info; 863 864 find_bad_casts_pass_info.pass = make_find_bad_casts_pass(); 865 find_bad_casts_pass_info.reference_pass_name = "ssa"; 866 find_bad_casts_pass_info.ref_pass_instance_number = 1; 867 find_bad_casts_pass_info.pos_op = PASS_POS_INSERT_AFTER; 868 869 if (!plugin_default_version_check(version, &gcc_version)) { 870 error(G_("incompatible gcc/plugin versions")); 871 return 1; 872 } 873 874 if (strncmp(lang_hooks.name, "GNU C", 5) && !strncmp(lang_hooks.name, "GNU C+", 6)) { 875 inform(UNKNOWN_LOCATION, G_("%s supports C only, not %s"), plugin_name, lang_hooks.name); 876 enable = false; 877 } 878 879 for (i = 0; i < argc; ++i) { 880 if (!strcmp(argv[i].key, "disable")) { 881 enable = false; 882 continue; 883 } 884 if (!strcmp(argv[i].key, "performance-mode")) { 885 performance_mode = 1; 886 continue; 887 } 888 error(G_("unknown option '-fplugin-arg-%s-%s'"), plugin_name, argv[i].key); 889 } 890 891 if (strlen(randstruct_seed) != 64) { 892 error(G_("invalid seed value supplied for %s plugin"), plugin_name); 893 return 1; 894 } 895 obtained_seed = sscanf(randstruct_seed, "%016llx%016llx%016llx%016llx", 896 &shuffle_seed[0], &shuffle_seed[1], &shuffle_seed[2], &shuffle_seed[3]); 897 if (obtained_seed != 4) { 898 error(G_("Invalid seed supplied for %s plugin"), plugin_name); 899 return 1; 900 } 901 902 register_callback(plugin_name, PLUGIN_INFO, NULL, &randomize_layout_plugin_info); 903 if (enable) { 904 register_callback(plugin_name, PLUGIN_ALL_IPA_PASSES_START, check_global_variables, NULL); 905 register_callback(plugin_name, PLUGIN_PASS_MANAGER_SETUP, NULL, &find_bad_casts_pass_info); 906 register_callback(plugin_name, PLUGIN_FINISH_TYPE, finish_type, NULL); 907 register_callback(plugin_name, PLUGIN_FINISH_DECL, randomize_layout_finish_decl, NULL); 908 } 909 register_callback(plugin_name, PLUGIN_ATTRIBUTES, register_attributes, NULL); 910 911 return 0; 912 } 913