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 = "201402201816vanilla", 38 .help = "disable\t\t\tdo not activate plugin\n" 39 "performance-mode\tenable cacheline-aware layout randomization\n" 40 }; 41 42 struct whitelist_entry { 43 const char *pathname; 44 const char *lhs; 45 const char *rhs; 46 }; 47 48 static const struct whitelist_entry whitelist[] = { 49 /* NIU overloads mapping with page struct */ 50 { "drivers/net/ethernet/sun/niu.c", "page", "address_space" }, 51 /* unix_skb_parms via UNIXCB() buffer */ 52 { "net/unix/af_unix.c", "unix_skb_parms", "char" }, 53 /* big_key payload.data struct splashing */ 54 { "security/keys/big_key.c", "path", "void *" }, 55 /* walk struct security_hook_heads as an array of struct list_head */ 56 { "security/security.c", "list_head", "security_hook_heads" }, 57 { } 58 }; 59 60 /* from old Linux dcache.h */ 61 static inline unsigned long 62 partial_name_hash(unsigned long c, unsigned long prevhash) 63 { 64 return (prevhash + (c << 4) + (c >> 4)) * 11; 65 } 66 static inline unsigned int 67 name_hash(const unsigned char *name) 68 { 69 unsigned long hash = 0; 70 unsigned int len = strlen((const char *)name); 71 while (len--) 72 hash = partial_name_hash(*name++, hash); 73 return (unsigned int)hash; 74 } 75 76 static tree handle_randomize_layout_attr(tree *node, tree name, tree args, int flags, bool *no_add_attrs) 77 { 78 tree type; 79 80 *no_add_attrs = true; 81 if (TREE_CODE(*node) == FUNCTION_DECL) { 82 error("%qE attribute does not apply to functions (%qF)", name, *node); 83 return NULL_TREE; 84 } 85 86 if (TREE_CODE(*node) == PARM_DECL) { 87 error("%qE attribute does not apply to function parameters (%qD)", name, *node); 88 return NULL_TREE; 89 } 90 91 if (TREE_CODE(*node) == VAR_DECL) { 92 error("%qE attribute does not apply to variables (%qD)", name, *node); 93 return NULL_TREE; 94 } 95 96 if (TYPE_P(*node)) { 97 type = *node; 98 } else { 99 gcc_assert(TREE_CODE(*node) == TYPE_DECL); 100 type = TREE_TYPE(*node); 101 } 102 103 if (TREE_CODE(type) != RECORD_TYPE) { 104 error("%qE attribute used on %qT applies to struct types only", name, type); 105 return NULL_TREE; 106 } 107 108 if (lookup_attribute(IDENTIFIER_POINTER(name), TYPE_ATTRIBUTES(type))) { 109 error("%qE attribute is already applied to the type %qT", name, type); 110 return NULL_TREE; 111 } 112 113 *no_add_attrs = false; 114 115 return NULL_TREE; 116 } 117 118 /* set on complete types that we don't need to inspect further at all */ 119 static tree handle_randomize_considered_attr(tree *node, tree name, tree args, int flags, bool *no_add_attrs) 120 { 121 *no_add_attrs = false; 122 return NULL_TREE; 123 } 124 125 /* 126 * set on types that we've performed a shuffle on, to prevent re-shuffling 127 * this does not preclude us from inspecting its fields for potential shuffles 128 */ 129 static tree handle_randomize_performed_attr(tree *node, tree name, tree args, int flags, bool *no_add_attrs) 130 { 131 *no_add_attrs = false; 132 return NULL_TREE; 133 } 134 135 /* 136 * 64bit variant of Bob Jenkins' public domain PRNG 137 * 256 bits of internal state 138 */ 139 140 typedef unsigned long long u64; 141 142 typedef struct ranctx { u64 a; u64 b; u64 c; u64 d; } ranctx; 143 144 #define rot(x,k) (((x)<<(k))|((x)>>(64-(k)))) 145 static u64 ranval(ranctx *x) { 146 u64 e = x->a - rot(x->b, 7); 147 x->a = x->b ^ rot(x->c, 13); 148 x->b = x->c + rot(x->d, 37); 149 x->c = x->d + e; 150 x->d = e + x->a; 151 return x->d; 152 } 153 154 static void raninit(ranctx *x, u64 *seed) { 155 int i; 156 157 x->a = seed[0]; 158 x->b = seed[1]; 159 x->c = seed[2]; 160 x->d = seed[3]; 161 162 for (i=0; i < 30; ++i) 163 (void)ranval(x); 164 } 165 166 static u64 shuffle_seed[4]; 167 168 struct partition_group { 169 tree tree_start; 170 unsigned long start; 171 unsigned long length; 172 }; 173 174 static void partition_struct(tree *fields, unsigned long length, struct partition_group *size_groups, unsigned long *num_groups) 175 { 176 unsigned long i; 177 unsigned long accum_size = 0; 178 unsigned long accum_length = 0; 179 unsigned long group_idx = 0; 180 181 gcc_assert(length < INT_MAX); 182 183 memset(size_groups, 0, sizeof(struct partition_group) * length); 184 185 for (i = 0; i < length; i++) { 186 if (size_groups[group_idx].tree_start == NULL_TREE) { 187 size_groups[group_idx].tree_start = fields[i]; 188 size_groups[group_idx].start = i; 189 accum_length = 0; 190 accum_size = 0; 191 } 192 accum_size += (unsigned long)int_size_in_bytes(TREE_TYPE(fields[i])); 193 accum_length++; 194 if (accum_size >= 64) { 195 size_groups[group_idx].length = accum_length; 196 accum_length = 0; 197 group_idx++; 198 } 199 } 200 201 if (size_groups[group_idx].tree_start != NULL_TREE && 202 !size_groups[group_idx].length) { 203 size_groups[group_idx].length = accum_length; 204 group_idx++; 205 } 206 207 *num_groups = group_idx; 208 } 209 210 static void performance_shuffle(tree *newtree, unsigned long length, ranctx *prng_state) 211 { 212 unsigned long i, x; 213 struct partition_group size_group[length]; 214 unsigned long num_groups = 0; 215 unsigned long randnum; 216 217 partition_struct(newtree, length, (struct partition_group *)&size_group, &num_groups); 218 for (i = num_groups - 1; i > 0; i--) { 219 struct partition_group tmp; 220 randnum = ranval(prng_state) % (i + 1); 221 tmp = size_group[i]; 222 size_group[i] = size_group[randnum]; 223 size_group[randnum] = tmp; 224 } 225 226 for (x = 0; x < num_groups; x++) { 227 for (i = size_group[x].start + size_group[x].length - 1; i > size_group[x].start; i--) { 228 tree tmp; 229 if (DECL_BIT_FIELD_TYPE(newtree[i])) 230 continue; 231 randnum = ranval(prng_state) % (i + 1); 232 // we could handle this case differently if desired 233 if (DECL_BIT_FIELD_TYPE(newtree[randnum])) 234 continue; 235 tmp = newtree[i]; 236 newtree[i] = newtree[randnum]; 237 newtree[randnum] = tmp; 238 } 239 } 240 } 241 242 static void full_shuffle(tree *newtree, unsigned long length, ranctx *prng_state) 243 { 244 unsigned long i, randnum; 245 246 for (i = length - 1; i > 0; i--) { 247 tree tmp; 248 randnum = ranval(prng_state) % (i + 1); 249 tmp = newtree[i]; 250 newtree[i] = newtree[randnum]; 251 newtree[randnum] = tmp; 252 } 253 } 254 255 /* modern in-place Fisher-Yates shuffle */ 256 static void shuffle(const_tree type, tree *newtree, unsigned long length) 257 { 258 unsigned long i; 259 u64 seed[4]; 260 ranctx prng_state; 261 const unsigned char *structname; 262 263 if (length == 0) 264 return; 265 266 gcc_assert(TREE_CODE(type) == RECORD_TYPE); 267 268 structname = ORIG_TYPE_NAME(type); 269 270 #ifdef __DEBUG_PLUGIN 271 fprintf(stderr, "Shuffling struct %s %p\n", (const char *)structname, type); 272 #ifdef __DEBUG_VERBOSE 273 debug_tree((tree)type); 274 #endif 275 #endif 276 277 for (i = 0; i < 4; i++) { 278 seed[i] = shuffle_seed[i]; 279 seed[i] ^= name_hash(structname); 280 } 281 282 raninit(&prng_state, (u64 *)&seed); 283 284 if (performance_mode) 285 performance_shuffle(newtree, length, &prng_state); 286 else 287 full_shuffle(newtree, length, &prng_state); 288 } 289 290 static bool is_flexible_array(const_tree field) 291 { 292 const_tree fieldtype; 293 const_tree typesize; 294 const_tree elemtype; 295 const_tree elemsize; 296 297 fieldtype = TREE_TYPE(field); 298 typesize = TYPE_SIZE(fieldtype); 299 300 if (TREE_CODE(fieldtype) != ARRAY_TYPE) 301 return false; 302 303 elemtype = TREE_TYPE(fieldtype); 304 elemsize = TYPE_SIZE(elemtype); 305 306 /* size of type is represented in bits */ 307 308 if (typesize == NULL_TREE && TYPE_DOMAIN(fieldtype) != NULL_TREE && 309 TYPE_MAX_VALUE(TYPE_DOMAIN(fieldtype)) == NULL_TREE) 310 return true; 311 312 if (typesize != NULL_TREE && 313 (TREE_CONSTANT(typesize) && (!tree_to_uhwi(typesize) || 314 tree_to_uhwi(typesize) == tree_to_uhwi(elemsize)))) 315 return true; 316 317 return false; 318 } 319 320 static int relayout_struct(tree type) 321 { 322 unsigned long num_fields = (unsigned long)list_length(TYPE_FIELDS(type)); 323 unsigned long shuffle_length = num_fields; 324 tree field; 325 tree newtree[num_fields]; 326 unsigned long i; 327 tree list; 328 tree variant; 329 tree main_variant; 330 expanded_location xloc; 331 bool has_flexarray = false; 332 333 if (TYPE_FIELDS(type) == NULL_TREE) 334 return 0; 335 336 if (num_fields < 2) 337 return 0; 338 339 gcc_assert(TREE_CODE(type) == RECORD_TYPE); 340 341 gcc_assert(num_fields < INT_MAX); 342 343 if (lookup_attribute("randomize_performed", TYPE_ATTRIBUTES(type)) || 344 lookup_attribute("no_randomize_layout", TYPE_ATTRIBUTES(TYPE_MAIN_VARIANT(type)))) 345 return 0; 346 347 /* Workaround for 3rd-party VirtualBox source that we can't modify ourselves */ 348 if (!strcmp((const char *)ORIG_TYPE_NAME(type), "INTNETTRUNKFACTORY") || 349 !strcmp((const char *)ORIG_TYPE_NAME(type), "RAWPCIFACTORY")) 350 return 0; 351 352 /* throw out any structs in uapi */ 353 xloc = expand_location(DECL_SOURCE_LOCATION(TYPE_FIELDS(type))); 354 355 if (strstr(xloc.file, "/uapi/")) 356 error(G_("attempted to randomize userland API struct %s"), ORIG_TYPE_NAME(type)); 357 358 for (field = TYPE_FIELDS(type), i = 0; field; field = TREE_CHAIN(field), i++) { 359 gcc_assert(TREE_CODE(field) == FIELD_DECL); 360 newtree[i] = field; 361 } 362 363 /* 364 * enforce that we don't randomize the layout of the last 365 * element of a struct if it's a 0 or 1-length array 366 * or a proper flexible array 367 */ 368 if (is_flexible_array(newtree[num_fields - 1])) { 369 has_flexarray = true; 370 shuffle_length--; 371 } 372 373 shuffle(type, (tree *)newtree, shuffle_length); 374 375 /* 376 * set up a bogus anonymous struct field designed to error out on unnamed struct initializers 377 * as gcc provides no other way to detect such code 378 */ 379 list = make_node(FIELD_DECL); 380 TREE_CHAIN(list) = newtree[0]; 381 TREE_TYPE(list) = void_type_node; 382 DECL_SIZE(list) = bitsize_zero_node; 383 DECL_NONADDRESSABLE_P(list) = 1; 384 DECL_FIELD_BIT_OFFSET(list) = bitsize_zero_node; 385 DECL_SIZE_UNIT(list) = size_zero_node; 386 DECL_FIELD_OFFSET(list) = size_zero_node; 387 DECL_CONTEXT(list) = type; 388 // to satisfy the constify plugin 389 TREE_READONLY(list) = 1; 390 391 for (i = 0; i < num_fields - 1; i++) 392 TREE_CHAIN(newtree[i]) = newtree[i+1]; 393 TREE_CHAIN(newtree[num_fields - 1]) = NULL_TREE; 394 395 main_variant = TYPE_MAIN_VARIANT(type); 396 for (variant = main_variant; variant; variant = TYPE_NEXT_VARIANT(variant)) { 397 TYPE_FIELDS(variant) = list; 398 TYPE_ATTRIBUTES(variant) = copy_list(TYPE_ATTRIBUTES(variant)); 399 TYPE_ATTRIBUTES(variant) = tree_cons(get_identifier("randomize_performed"), NULL_TREE, TYPE_ATTRIBUTES(variant)); 400 TYPE_ATTRIBUTES(variant) = tree_cons(get_identifier("designated_init"), NULL_TREE, TYPE_ATTRIBUTES(variant)); 401 if (has_flexarray) 402 TYPE_ATTRIBUTES(type) = tree_cons(get_identifier("has_flexarray"), NULL_TREE, TYPE_ATTRIBUTES(type)); 403 } 404 405 /* 406 * force a re-layout of the main variant 407 * the TYPE_SIZE for all variants will be recomputed 408 * by finalize_type_size() 409 */ 410 TYPE_SIZE(main_variant) = NULL_TREE; 411 layout_type(main_variant); 412 gcc_assert(TYPE_SIZE(main_variant) != NULL_TREE); 413 414 return 1; 415 } 416 417 /* from constify plugin */ 418 static const_tree get_field_type(const_tree field) 419 { 420 return strip_array_types(TREE_TYPE(field)); 421 } 422 423 /* from constify plugin */ 424 static bool is_fptr(const_tree fieldtype) 425 { 426 if (TREE_CODE(fieldtype) != POINTER_TYPE) 427 return false; 428 429 return TREE_CODE(TREE_TYPE(fieldtype)) == FUNCTION_TYPE; 430 } 431 432 /* derived from constify plugin */ 433 static int is_pure_ops_struct(const_tree node) 434 { 435 const_tree field; 436 437 gcc_assert(TREE_CODE(node) == RECORD_TYPE || TREE_CODE(node) == UNION_TYPE); 438 439 for (field = TYPE_FIELDS(node); field; field = TREE_CHAIN(field)) { 440 const_tree fieldtype = get_field_type(field); 441 enum tree_code code = TREE_CODE(fieldtype); 442 443 if (node == fieldtype) 444 continue; 445 446 if (!is_fptr(fieldtype)) 447 return 0; 448 449 if (code != RECORD_TYPE && code != UNION_TYPE) 450 continue; 451 452 if (!is_pure_ops_struct(fieldtype)) 453 return 0; 454 } 455 456 return 1; 457 } 458 459 static void randomize_type(tree type) 460 { 461 tree variant; 462 463 gcc_assert(TREE_CODE(type) == RECORD_TYPE); 464 465 if (lookup_attribute("randomize_considered", TYPE_ATTRIBUTES(type))) 466 return; 467 468 if (lookup_attribute("randomize_layout", TYPE_ATTRIBUTES(TYPE_MAIN_VARIANT(type))) || is_pure_ops_struct(type)) 469 relayout_struct(type); 470 471 for (variant = TYPE_MAIN_VARIANT(type); variant; variant = TYPE_NEXT_VARIANT(variant)) { 472 TYPE_ATTRIBUTES(type) = copy_list(TYPE_ATTRIBUTES(type)); 473 TYPE_ATTRIBUTES(type) = tree_cons(get_identifier("randomize_considered"), NULL_TREE, TYPE_ATTRIBUTES(type)); 474 } 475 #ifdef __DEBUG_PLUGIN 476 fprintf(stderr, "Marking randomize_considered on struct %s\n", ORIG_TYPE_NAME(type)); 477 #ifdef __DEBUG_VERBOSE 478 debug_tree(type); 479 #endif 480 #endif 481 } 482 483 static void update_decl_size(tree decl) 484 { 485 tree lastval, lastidx, field, init, type, flexsize; 486 unsigned HOST_WIDE_INT len; 487 488 type = TREE_TYPE(decl); 489 490 if (!lookup_attribute("has_flexarray", TYPE_ATTRIBUTES(type))) 491 return; 492 493 init = DECL_INITIAL(decl); 494 if (init == NULL_TREE || init == error_mark_node) 495 return; 496 497 if (TREE_CODE(init) != CONSTRUCTOR) 498 return; 499 500 len = CONSTRUCTOR_NELTS(init); 501 if (!len) 502 return; 503 504 lastval = CONSTRUCTOR_ELT(init, CONSTRUCTOR_NELTS(init) - 1)->value; 505 lastidx = CONSTRUCTOR_ELT(init, CONSTRUCTOR_NELTS(init) - 1)->index; 506 507 for (field = TYPE_FIELDS(TREE_TYPE(decl)); TREE_CHAIN(field); field = TREE_CHAIN(field)) 508 ; 509 510 if (lastidx != field) 511 return; 512 513 if (TREE_CODE(lastval) != STRING_CST) { 514 error("Only string constants are supported as initializers " 515 "for randomized structures with flexible arrays"); 516 return; 517 } 518 519 flexsize = bitsize_int(TREE_STRING_LENGTH(lastval) * 520 tree_to_uhwi(TYPE_SIZE(TREE_TYPE(TREE_TYPE(lastval))))); 521 522 DECL_SIZE(decl) = size_binop(PLUS_EXPR, TYPE_SIZE(type), flexsize); 523 524 return; 525 } 526 527 528 static void randomize_layout_finish_decl(void *event_data, void *data) 529 { 530 tree decl = (tree)event_data; 531 tree type; 532 533 if (decl == NULL_TREE || decl == error_mark_node) 534 return; 535 536 type = TREE_TYPE(decl); 537 538 if (TREE_CODE(decl) != VAR_DECL) 539 return; 540 541 if (TREE_CODE(type) != RECORD_TYPE && TREE_CODE(type) != UNION_TYPE) 542 return; 543 544 if (!lookup_attribute("randomize_performed", TYPE_ATTRIBUTES(type))) 545 return; 546 547 DECL_SIZE(decl) = 0; 548 DECL_SIZE_UNIT(decl) = 0; 549 SET_DECL_ALIGN(decl, 0); 550 SET_DECL_MODE (decl, VOIDmode); 551 SET_DECL_RTL(decl, 0); 552 update_decl_size(decl); 553 layout_decl(decl, 0); 554 } 555 556 static void finish_type(void *event_data, void *data) 557 { 558 tree type = (tree)event_data; 559 560 if (type == NULL_TREE || type == error_mark_node) 561 return; 562 563 if (TREE_CODE(type) != RECORD_TYPE) 564 return; 565 566 if (TYPE_FIELDS(type) == NULL_TREE) 567 return; 568 569 if (lookup_attribute("randomize_considered", TYPE_ATTRIBUTES(type))) 570 return; 571 572 #ifdef __DEBUG_PLUGIN 573 fprintf(stderr, "Calling randomize_type on %s\n", ORIG_TYPE_NAME(type)); 574 #endif 575 #ifdef __DEBUG_VERBOSE 576 debug_tree(type); 577 #endif 578 randomize_type(type); 579 580 return; 581 } 582 583 static struct attribute_spec randomize_layout_attr = { 584 .name = "randomize_layout", 585 // related to args 586 .min_length = 0, 587 .max_length = 0, 588 .decl_required = false, 589 // need type declaration 590 .type_required = true, 591 .function_type_required = false, 592 .handler = handle_randomize_layout_attr, 593 #if BUILDING_GCC_VERSION >= 4007 594 .affects_type_identity = true 595 #endif 596 }; 597 598 static struct attribute_spec no_randomize_layout_attr = { 599 .name = "no_randomize_layout", 600 // related to args 601 .min_length = 0, 602 .max_length = 0, 603 .decl_required = false, 604 // need type declaration 605 .type_required = true, 606 .function_type_required = false, 607 .handler = handle_randomize_layout_attr, 608 #if BUILDING_GCC_VERSION >= 4007 609 .affects_type_identity = true 610 #endif 611 }; 612 613 static struct attribute_spec randomize_considered_attr = { 614 .name = "randomize_considered", 615 // related to args 616 .min_length = 0, 617 .max_length = 0, 618 .decl_required = false, 619 // need type declaration 620 .type_required = true, 621 .function_type_required = false, 622 .handler = handle_randomize_considered_attr, 623 #if BUILDING_GCC_VERSION >= 4007 624 .affects_type_identity = false 625 #endif 626 }; 627 628 static struct attribute_spec randomize_performed_attr = { 629 .name = "randomize_performed", 630 // related to args 631 .min_length = 0, 632 .max_length = 0, 633 .decl_required = false, 634 // need type declaration 635 .type_required = true, 636 .function_type_required = false, 637 .handler = handle_randomize_performed_attr, 638 #if BUILDING_GCC_VERSION >= 4007 639 .affects_type_identity = false 640 #endif 641 }; 642 643 static void register_attributes(void *event_data, void *data) 644 { 645 register_attribute(&randomize_layout_attr); 646 register_attribute(&no_randomize_layout_attr); 647 register_attribute(&randomize_considered_attr); 648 register_attribute(&randomize_performed_attr); 649 } 650 651 static void check_bad_casts_in_constructor(tree var, tree init) 652 { 653 unsigned HOST_WIDE_INT idx; 654 tree field, val; 655 tree field_type, val_type; 656 657 FOR_EACH_CONSTRUCTOR_ELT(CONSTRUCTOR_ELTS(init), idx, field, val) { 658 if (TREE_CODE(val) == CONSTRUCTOR) { 659 check_bad_casts_in_constructor(var, val); 660 continue; 661 } 662 663 /* pipacs' plugin creates franken-arrays that differ from those produced by 664 normal code which all have valid 'field' trees. work around this */ 665 if (field == NULL_TREE) 666 continue; 667 field_type = TREE_TYPE(field); 668 val_type = TREE_TYPE(val); 669 670 if (TREE_CODE(field_type) != POINTER_TYPE || TREE_CODE(val_type) != POINTER_TYPE) 671 continue; 672 673 if (field_type == val_type) 674 continue; 675 676 field_type = TYPE_MAIN_VARIANT(strip_array_types(TYPE_MAIN_VARIANT(TREE_TYPE(field_type)))); 677 val_type = TYPE_MAIN_VARIANT(strip_array_types(TYPE_MAIN_VARIANT(TREE_TYPE(val_type)))); 678 679 if (field_type == void_type_node) 680 continue; 681 if (field_type == val_type) 682 continue; 683 if (TREE_CODE(val_type) != RECORD_TYPE) 684 continue; 685 686 if (!lookup_attribute("randomize_performed", TYPE_ATTRIBUTES(val_type))) 687 continue; 688 MISMATCH(DECL_SOURCE_LOCATION(var), "constructor\n", TYPE_MAIN_VARIANT(field_type), TYPE_MAIN_VARIANT(val_type)); 689 } 690 } 691 692 /* derived from the constify plugin */ 693 static void check_global_variables(void *event_data, void *data) 694 { 695 struct varpool_node *node; 696 tree init; 697 698 FOR_EACH_VARIABLE(node) { 699 tree var = NODE_DECL(node); 700 init = DECL_INITIAL(var); 701 if (init == NULL_TREE) 702 continue; 703 704 if (TREE_CODE(init) != CONSTRUCTOR) 705 continue; 706 707 check_bad_casts_in_constructor(var, init); 708 } 709 } 710 711 static bool dominated_by_is_err(const_tree rhs, basic_block bb) 712 { 713 basic_block dom; 714 gimple dom_stmt; 715 gimple call_stmt; 716 const_tree dom_lhs; 717 const_tree poss_is_err_cond; 718 const_tree poss_is_err_func; 719 const_tree is_err_arg; 720 721 dom = get_immediate_dominator(CDI_DOMINATORS, bb); 722 if (!dom) 723 return false; 724 725 dom_stmt = last_stmt(dom); 726 if (!dom_stmt) 727 return false; 728 729 if (gimple_code(dom_stmt) != GIMPLE_COND) 730 return false; 731 732 if (gimple_cond_code(dom_stmt) != NE_EXPR) 733 return false; 734 735 if (!integer_zerop(gimple_cond_rhs(dom_stmt))) 736 return false; 737 738 poss_is_err_cond = gimple_cond_lhs(dom_stmt); 739 740 if (TREE_CODE(poss_is_err_cond) != SSA_NAME) 741 return false; 742 743 call_stmt = SSA_NAME_DEF_STMT(poss_is_err_cond); 744 745 if (gimple_code(call_stmt) != GIMPLE_CALL) 746 return false; 747 748 dom_lhs = gimple_get_lhs(call_stmt); 749 poss_is_err_func = gimple_call_fndecl(call_stmt); 750 if (!poss_is_err_func) 751 return false; 752 if (dom_lhs != poss_is_err_cond) 753 return false; 754 if (strcmp(DECL_NAME_POINTER(poss_is_err_func), "IS_ERR")) 755 return false; 756 757 is_err_arg = gimple_call_arg(call_stmt, 0); 758 if (!is_err_arg) 759 return false; 760 761 if (is_err_arg != rhs) 762 return false; 763 764 return true; 765 } 766 767 static void handle_local_var_initializers(void) 768 { 769 tree var; 770 unsigned int i; 771 772 FOR_EACH_LOCAL_DECL(cfun, i, var) { 773 tree init = DECL_INITIAL(var); 774 if (!init) 775 continue; 776 if (TREE_CODE(init) != CONSTRUCTOR) 777 continue; 778 check_bad_casts_in_constructor(var, init); 779 } 780 } 781 782 static bool type_name_eq(gimple stmt, const_tree type_tree, const char *wanted_name) 783 { 784 const char *type_name; 785 786 if (type_tree == NULL_TREE) 787 return false; 788 789 switch (TREE_CODE(type_tree)) { 790 case RECORD_TYPE: 791 type_name = TYPE_NAME_POINTER(type_tree); 792 break; 793 case INTEGER_TYPE: 794 if (TYPE_PRECISION(type_tree) == CHAR_TYPE_SIZE) 795 type_name = "char"; 796 else { 797 INFORM(gimple_location(stmt), "found non-char INTEGER_TYPE cast comparison: %qT\n", type_tree); 798 debug_tree(type_tree); 799 return false; 800 } 801 break; 802 case POINTER_TYPE: 803 if (TREE_CODE(TREE_TYPE(type_tree)) == VOID_TYPE) { 804 type_name = "void *"; 805 break; 806 } else { 807 INFORM(gimple_location(stmt), "found non-void POINTER_TYPE cast comparison %qT\n", type_tree); 808 debug_tree(type_tree); 809 return false; 810 } 811 default: 812 INFORM(gimple_location(stmt), "unhandled cast comparison: %qT\n", type_tree); 813 debug_tree(type_tree); 814 return false; 815 } 816 817 return strcmp(type_name, wanted_name) == 0; 818 } 819 820 static bool whitelisted_cast(gimple stmt, const_tree lhs_tree, const_tree rhs_tree) 821 { 822 const struct whitelist_entry *entry; 823 expanded_location xloc = expand_location(gimple_location(stmt)); 824 825 for (entry = whitelist; entry->pathname; entry++) { 826 if (!strstr(xloc.file, entry->pathname)) 827 continue; 828 829 if (type_name_eq(stmt, lhs_tree, entry->lhs) && type_name_eq(stmt, rhs_tree, entry->rhs)) 830 return true; 831 } 832 833 return false; 834 } 835 836 /* 837 * iterate over all statements to find "bad" casts: 838 * those where the address of the start of a structure is cast 839 * to a pointer of a structure of a different type, or a 840 * structure pointer type is cast to a different structure pointer type 841 */ 842 static unsigned int find_bad_casts_execute(void) 843 { 844 basic_block bb; 845 846 handle_local_var_initializers(); 847 848 FOR_EACH_BB_FN(bb, cfun) { 849 gimple_stmt_iterator gsi; 850 851 for (gsi = gsi_start_bb(bb); !gsi_end_p(gsi); gsi_next(&gsi)) { 852 gimple stmt; 853 const_tree lhs; 854 const_tree lhs_type; 855 const_tree rhs1; 856 const_tree rhs_type; 857 const_tree ptr_lhs_type; 858 const_tree ptr_rhs_type; 859 const_tree op0; 860 const_tree op0_type; 861 enum tree_code rhs_code; 862 863 stmt = gsi_stmt(gsi); 864 865 #ifdef __DEBUG_PLUGIN 866 #ifdef __DEBUG_VERBOSE 867 debug_gimple_stmt(stmt); 868 debug_tree(gimple_get_lhs(stmt)); 869 #endif 870 #endif 871 872 if (gimple_code(stmt) != GIMPLE_ASSIGN) 873 continue; 874 875 #ifdef __DEBUG_PLUGIN 876 #ifdef __DEBUG_VERBOSE 877 debug_tree(gimple_assign_rhs1(stmt)); 878 #endif 879 #endif 880 881 882 rhs_code = gimple_assign_rhs_code(stmt); 883 884 if (rhs_code != ADDR_EXPR && rhs_code != SSA_NAME) 885 continue; 886 887 lhs = gimple_get_lhs(stmt); 888 lhs_type = TREE_TYPE(lhs); 889 rhs1 = gimple_assign_rhs1(stmt); 890 rhs_type = TREE_TYPE(rhs1); 891 892 if (TREE_CODE(rhs_type) != POINTER_TYPE || 893 TREE_CODE(lhs_type) != POINTER_TYPE) 894 continue; 895 896 ptr_lhs_type = TYPE_MAIN_VARIANT(strip_array_types(TYPE_MAIN_VARIANT(TREE_TYPE(lhs_type)))); 897 ptr_rhs_type = TYPE_MAIN_VARIANT(strip_array_types(TYPE_MAIN_VARIANT(TREE_TYPE(rhs_type)))); 898 899 if (ptr_rhs_type == void_type_node) 900 continue; 901 902 if (ptr_lhs_type == void_type_node) 903 continue; 904 905 if (dominated_by_is_err(rhs1, bb)) 906 continue; 907 908 if (TREE_CODE(ptr_rhs_type) != RECORD_TYPE) { 909 #ifndef __DEBUG_PLUGIN 910 if (lookup_attribute("randomize_performed", TYPE_ATTRIBUTES(ptr_lhs_type))) 911 #endif 912 { 913 if (!whitelisted_cast(stmt, ptr_lhs_type, ptr_rhs_type)) 914 MISMATCH(gimple_location(stmt), "rhs", ptr_lhs_type, ptr_rhs_type); 915 } 916 continue; 917 } 918 919 if (rhs_code == SSA_NAME && ptr_lhs_type == ptr_rhs_type) 920 continue; 921 922 if (rhs_code == ADDR_EXPR) { 923 op0 = TREE_OPERAND(rhs1, 0); 924 925 if (op0 == NULL_TREE) 926 continue; 927 928 if (TREE_CODE(op0) != VAR_DECL) 929 continue; 930 931 op0_type = TYPE_MAIN_VARIANT(strip_array_types(TYPE_MAIN_VARIANT(TREE_TYPE(op0)))); 932 if (op0_type == ptr_lhs_type) 933 continue; 934 935 #ifndef __DEBUG_PLUGIN 936 if (lookup_attribute("randomize_performed", TYPE_ATTRIBUTES(op0_type))) 937 #endif 938 { 939 if (!whitelisted_cast(stmt, ptr_lhs_type, op0_type)) 940 MISMATCH(gimple_location(stmt), "op0", ptr_lhs_type, op0_type); 941 } 942 } else { 943 const_tree ssa_name_var = SSA_NAME_VAR(rhs1); 944 /* skip bogus type casts introduced by container_of */ 945 if (ssa_name_var != NULL_TREE && DECL_NAME(ssa_name_var) && 946 !strcmp((const char *)DECL_NAME_POINTER(ssa_name_var), "__mptr")) 947 continue; 948 #ifndef __DEBUG_PLUGIN 949 if (lookup_attribute("randomize_performed", TYPE_ATTRIBUTES(ptr_rhs_type))) 950 #endif 951 { 952 if (!whitelisted_cast(stmt, ptr_lhs_type, ptr_rhs_type)) 953 MISMATCH(gimple_location(stmt), "ssa", ptr_lhs_type, ptr_rhs_type); 954 } 955 } 956 957 } 958 } 959 return 0; 960 } 961 962 #define PASS_NAME find_bad_casts 963 #define NO_GATE 964 #define TODO_FLAGS_FINISH TODO_dump_func 965 #include "gcc-generate-gimple-pass.h" 966 967 __visible int plugin_init(struct plugin_name_args *plugin_info, struct plugin_gcc_version *version) 968 { 969 int i; 970 const char * const plugin_name = plugin_info->base_name; 971 const int argc = plugin_info->argc; 972 const struct plugin_argument * const argv = plugin_info->argv; 973 bool enable = true; 974 int obtained_seed = 0; 975 struct register_pass_info find_bad_casts_pass_info; 976 977 find_bad_casts_pass_info.pass = make_find_bad_casts_pass(); 978 find_bad_casts_pass_info.reference_pass_name = "ssa"; 979 find_bad_casts_pass_info.ref_pass_instance_number = 1; 980 find_bad_casts_pass_info.pos_op = PASS_POS_INSERT_AFTER; 981 982 if (!plugin_default_version_check(version, &gcc_version)) { 983 error(G_("incompatible gcc/plugin versions")); 984 return 1; 985 } 986 987 if (strncmp(lang_hooks.name, "GNU C", 5) && !strncmp(lang_hooks.name, "GNU C+", 6)) { 988 inform(UNKNOWN_LOCATION, G_("%s supports C only, not %s"), plugin_name, lang_hooks.name); 989 enable = false; 990 } 991 992 for (i = 0; i < argc; ++i) { 993 if (!strcmp(argv[i].key, "disable")) { 994 enable = false; 995 continue; 996 } 997 if (!strcmp(argv[i].key, "performance-mode")) { 998 performance_mode = 1; 999 continue; 1000 } 1001 error(G_("unknown option '-fplugin-arg-%s-%s'"), plugin_name, argv[i].key); 1002 } 1003 1004 if (strlen(randstruct_seed) != 64) { 1005 error(G_("invalid seed value supplied for %s plugin"), plugin_name); 1006 return 1; 1007 } 1008 obtained_seed = sscanf(randstruct_seed, "%016llx%016llx%016llx%016llx", 1009 &shuffle_seed[0], &shuffle_seed[1], &shuffle_seed[2], &shuffle_seed[3]); 1010 if (obtained_seed != 4) { 1011 error(G_("Invalid seed supplied for %s plugin"), plugin_name); 1012 return 1; 1013 } 1014 1015 register_callback(plugin_name, PLUGIN_INFO, NULL, &randomize_layout_plugin_info); 1016 if (enable) { 1017 register_callback(plugin_name, PLUGIN_ALL_IPA_PASSES_START, check_global_variables, NULL); 1018 register_callback(plugin_name, PLUGIN_PASS_MANAGER_SETUP, NULL, &find_bad_casts_pass_info); 1019 register_callback(plugin_name, PLUGIN_FINISH_TYPE, finish_type, NULL); 1020 register_callback(plugin_name, PLUGIN_FINISH_DECL, randomize_layout_finish_decl, NULL); 1021 } 1022 register_callback(plugin_name, PLUGIN_ATTRIBUTES, register_attributes, NULL); 1023 1024 return 0; 1025 } 1026