scripts/gcc-plugins/randomize_layout_plugin.c

   1 /*
   2  * Copyright 2014-2016 by Open Source Security, Inc., Brad Spengler <[email protected]>
   3  *                   and PaX Team <[email protected]>
   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 }