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