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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
30static int performance_mode;
31
32static 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 */
39static inline unsigned long
40partial_name_hash(unsigned long c, unsigned long prevhash)
41{
42 return (prevhash + (c << 4) + (c >> 4)) * 11;
43}
44static inline unsigned int
45name_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
54static 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 if (TREE_CODE(*node) == FIELD_DECL) {
77 *no_add_attrs = false;
78 return NULL_TREE;
79 } else {
80 gcc_assert(TREE_CODE(*node) == TYPE_DECL);
81 type = TREE_TYPE(*node);
82 }
83
84 if (TREE_CODE(type) != RECORD_TYPE) {
85 error("%qE attribute used on %qT applies to struct types only", name, type);
86 return NULL_TREE;
87 }
88
89 if (lookup_attribute(IDENTIFIER_POINTER(name), TYPE_ATTRIBUTES(type))) {
90 error("%qE attribute is already applied to the type %qT", name, type);
91 return NULL_TREE;
92 }
93
94 *no_add_attrs = false;
95
96 return NULL_TREE;
97}
98
99/* set on complete types that we don't need to inspect further at all */
100static tree handle_randomize_considered_attr(tree *node, tree name, tree args, int flags, bool *no_add_attrs)
101{
102 *no_add_attrs = false;
103 return NULL_TREE;
104}
105
106/*
107 * set on types that we've performed a shuffle on, to prevent re-shuffling
108 * this does not preclude us from inspecting its fields for potential shuffles
109 */
110static tree handle_randomize_performed_attr(tree *node, tree name, tree args, int flags, bool *no_add_attrs)
111{
112 *no_add_attrs = false;
113 return NULL_TREE;
114}
115
116/*
117 * 64bit variant of Bob Jenkins' public domain PRNG
118 * 256 bits of internal state
119 */
120
121typedef unsigned long long u64;
122
123typedef struct ranctx { u64 a; u64 b; u64 c; u64 d; } ranctx;
124
125#define rot(x,k) (((x)<<(k))|((x)>>(64-(k))))
126static u64 ranval(ranctx *x) {
127 u64 e = x->a - rot(x->b, 7);
128 x->a = x->b ^ rot(x->c, 13);
129 x->b = x->c + rot(x->d, 37);
130 x->c = x->d + e;
131 x->d = e + x->a;
132 return x->d;
133}
134
135static void raninit(ranctx *x, u64 *seed) {
136 int i;
137
138 x->a = seed[0];
139 x->b = seed[1];
140 x->c = seed[2];
141 x->d = seed[3];
142
143 for (i=0; i < 30; ++i)
144 (void)ranval(x);
145}
146
147static u64 shuffle_seed[4];
148
149struct partition_group {
150 tree tree_start;
151 unsigned long start;
152 unsigned long length;
153};
154
155static void partition_struct(tree *fields, unsigned long length, struct partition_group *size_groups, unsigned long *num_groups)
156{
157 unsigned long i;
158 unsigned long accum_size = 0;
159 unsigned long accum_length = 0;
160 unsigned long group_idx = 0;
161
162 gcc_assert(length < INT_MAX);
163
164 memset(size_groups, 0, sizeof(struct partition_group) * length);
165
166 for (i = 0; i < length; i++) {
167 if (size_groups[group_idx].tree_start == NULL_TREE) {
168 size_groups[group_idx].tree_start = fields[i];
169 size_groups[group_idx].start = i;
170 accum_length = 0;
171 accum_size = 0;
172 }
173 accum_size += (unsigned long)int_size_in_bytes(TREE_TYPE(fields[i]));
174 accum_length++;
175 if (accum_size >= 64) {
176 size_groups[group_idx].length = accum_length;
177 accum_length = 0;
178 group_idx++;
179 }
180 }
181
182 if (size_groups[group_idx].tree_start != NULL_TREE &&
183 !size_groups[group_idx].length) {
184 size_groups[group_idx].length = accum_length;
185 group_idx++;
186 }
187
188 *num_groups = group_idx;
189}
190
191static void performance_shuffle(tree *newtree, unsigned long length, ranctx *prng_state)
192{
193 unsigned long i, x, index;
194 struct partition_group size_group[length];
195 unsigned long num_groups = 0;
196 unsigned long randnum;
197
198 partition_struct(newtree, length, (struct partition_group *)&size_group, &num_groups);
199
200 /* FIXME: this group shuffle is currently a no-op. */
201 for (i = num_groups - 1; i > 0; i--) {
202 struct partition_group tmp;
203 randnum = ranval(prng_state) % (i + 1);
204 tmp = size_group[i];
205 size_group[i] = size_group[randnum];
206 size_group[randnum] = tmp;
207 }
208
209 for (x = 0; x < num_groups; x++) {
210 for (index = size_group[x].length - 1; index > 0; index--) {
211 tree tmp;
212
213 i = size_group[x].start + index;
214 if (DECL_BIT_FIELD_TYPE(newtree[i]))
215 continue;
216 randnum = ranval(prng_state) % (index + 1);
217 randnum += size_group[x].start;
218 // we could handle this case differently if desired
219 if (DECL_BIT_FIELD_TYPE(newtree[randnum]))
220 continue;
221 tmp = newtree[i];
222 newtree[i] = newtree[randnum];
223 newtree[randnum] = tmp;
224 }
225 }
226}
227
228static void full_shuffle(tree *newtree, unsigned long length, ranctx *prng_state)
229{
230 unsigned long i, randnum;
231
232 for (i = length - 1; i > 0; i--) {
233 tree tmp;
234 randnum = ranval(prng_state) % (i + 1);
235 tmp = newtree[i];
236 newtree[i] = newtree[randnum];
237 newtree[randnum] = tmp;
238 }
239}
240
241/* modern in-place Fisher-Yates shuffle */
242static void shuffle(const_tree type, tree *newtree, unsigned long length)
243{
244 unsigned long i;
245 u64 seed[4];
246 ranctx prng_state;
247 const unsigned char *structname;
248
249 if (length == 0)
250 return;
251
252 gcc_assert(TREE_CODE(type) == RECORD_TYPE);
253
254 structname = ORIG_TYPE_NAME(type);
255
256#ifdef __DEBUG_PLUGIN
257 fprintf(stderr, "Shuffling struct %s %p\n", (const char *)structname, type);
258#ifdef __DEBUG_VERBOSE
259 debug_tree((tree)type);
260#endif
261#endif
262
263 for (i = 0; i < 4; i++) {
264 seed[i] = shuffle_seed[i];
265 seed[i] ^= name_hash(structname);
266 }
267
268 raninit(&prng_state, (u64 *)&seed);
269
270 if (performance_mode)
271 performance_shuffle(newtree, length, &prng_state);
272 else
273 full_shuffle(newtree, length, &prng_state);
274}
275
276static bool is_flexible_array(const_tree field)
277{
278 const_tree fieldtype;
279 const_tree typesize;
280
281 fieldtype = TREE_TYPE(field);
282 typesize = TYPE_SIZE(fieldtype);
283
284 if (TREE_CODE(fieldtype) != ARRAY_TYPE)
285 return false;
286
287 /* size of type is represented in bits */
288
289 if (typesize == NULL_TREE && TYPE_DOMAIN(fieldtype) != NULL_TREE &&
290 TYPE_MAX_VALUE(TYPE_DOMAIN(fieldtype)) == NULL_TREE)
291 return true;
292
293 return false;
294}
295
296static int relayout_struct(tree type)
297{
298 unsigned long num_fields = (unsigned long)list_length(TYPE_FIELDS(type));
299 unsigned long shuffle_length = num_fields;
300 tree field;
301 tree newtree[num_fields];
302 unsigned long i;
303 tree list;
304 tree variant;
305 tree main_variant;
306 expanded_location xloc;
307 bool has_flexarray = false;
308
309 if (TYPE_FIELDS(type) == NULL_TREE)
310 return 0;
311
312 if (num_fields < 2)
313 return 0;
314
315 gcc_assert(TREE_CODE(type) == RECORD_TYPE);
316
317 gcc_assert(num_fields < INT_MAX);
318
319 if (lookup_attribute("randomize_performed", TYPE_ATTRIBUTES(type)) ||
320 lookup_attribute("no_randomize_layout", TYPE_ATTRIBUTES(TYPE_MAIN_VARIANT(type))))
321 return 0;
322
323 /* Workaround for 3rd-party VirtualBox source that we can't modify ourselves */
324 if (!strcmp((const char *)ORIG_TYPE_NAME(type), "INTNETTRUNKFACTORY") ||
325 !strcmp((const char *)ORIG_TYPE_NAME(type), "RAWPCIFACTORY"))
326 return 0;
327
328 /* throw out any structs in uapi */
329 xloc = expand_location(DECL_SOURCE_LOCATION(TYPE_FIELDS(type)));
330
331 if (strstr(xloc.file, "/uapi/"))
332 error(G_("attempted to randomize userland API struct %s"), ORIG_TYPE_NAME(type));
333
334 for (field = TYPE_FIELDS(type), i = 0; field; field = TREE_CHAIN(field), i++) {
335 gcc_assert(TREE_CODE(field) == FIELD_DECL);
336 newtree[i] = field;
337 }
338
339 /*
340 * enforce that we don't randomize the layout of the last
341 * element of a struct if it's a proper flexible array
342 */
343 if (is_flexible_array(newtree[num_fields - 1])) {
344 has_flexarray = true;
345 shuffle_length--;
346 }
347
348 shuffle(type, (tree *)newtree, shuffle_length);
349
350 for (i = 0; i < num_fields - 1; i++)
351 TREE_CHAIN(newtree[i]) = newtree[i+1];
352 TREE_CHAIN(newtree[num_fields - 1]) = NULL_TREE;
353
354 add_type_attr(type, "randomize_performed", NULL_TREE);
355 add_type_attr(type, "designated_init", NULL_TREE);
356 if (has_flexarray)
357 add_type_attr(type, "has_flexarray", NULL_TREE);
358
359 main_variant = TYPE_MAIN_VARIANT(type);
360 for (variant = main_variant; variant; variant = TYPE_NEXT_VARIANT(variant))
361 TYPE_FIELDS(variant) = newtree[0];
362
363 /*
364 * force a re-layout of the main variant
365 * the TYPE_SIZE for all variants will be recomputed
366 * by finalize_type_size()
367 */
368 TYPE_SIZE(main_variant) = NULL_TREE;
369 layout_type(main_variant);
370 gcc_assert(TYPE_SIZE(main_variant) != NULL_TREE);
371
372 return 1;
373}
374
375/* from constify plugin */
376static const_tree get_field_type(const_tree field)
377{
378 return strip_array_types(TREE_TYPE(field));
379}
380
381/* from constify plugin */
382static bool is_fptr(const_tree fieldtype)
383{
384 if (TREE_CODE(fieldtype) != POINTER_TYPE)
385 return false;
386
387 return TREE_CODE(TREE_TYPE(fieldtype)) == FUNCTION_TYPE;
388}
389
390/* derived from constify plugin */
391static int is_pure_ops_struct(const_tree node)
392{
393 const_tree field;
394
395 gcc_assert(TREE_CODE(node) == RECORD_TYPE || TREE_CODE(node) == UNION_TYPE);
396
397 for (field = TYPE_FIELDS(node); field; field = TREE_CHAIN(field)) {
398 const_tree fieldtype = get_field_type(field);
399 enum tree_code code = TREE_CODE(fieldtype);
400
401 if (node == fieldtype)
402 continue;
403
404 if (code == RECORD_TYPE || code == UNION_TYPE) {
405 if (!is_pure_ops_struct(fieldtype))
406 return 0;
407 continue;
408 }
409
410 if (!is_fptr(fieldtype))
411 return 0;
412 }
413
414 return 1;
415}
416
417static void randomize_type(tree type)
418{
419 tree variant;
420
421 gcc_assert(TREE_CODE(type) == RECORD_TYPE);
422
423 if (lookup_attribute("randomize_considered", TYPE_ATTRIBUTES(type)))
424 return;
425
426 if (lookup_attribute("randomize_layout", TYPE_ATTRIBUTES(TYPE_MAIN_VARIANT(type))) || is_pure_ops_struct(type))
427 relayout_struct(type);
428
429 add_type_attr(type, "randomize_considered", NULL_TREE);
430
431#ifdef __DEBUG_PLUGIN
432 fprintf(stderr, "Marking randomize_considered on struct %s\n", ORIG_TYPE_NAME(type));
433#ifdef __DEBUG_VERBOSE
434 debug_tree(type);
435#endif
436#endif
437}
438
439static void update_decl_size(tree decl)
440{
441 tree lastval, lastidx, field, init, type, flexsize;
442 unsigned HOST_WIDE_INT len;
443
444 type = TREE_TYPE(decl);
445
446 if (!lookup_attribute("has_flexarray", TYPE_ATTRIBUTES(type)))
447 return;
448
449 init = DECL_INITIAL(decl);
450 if (init == NULL_TREE || init == error_mark_node)
451 return;
452
453 if (TREE_CODE(init) != CONSTRUCTOR)
454 return;
455
456 len = CONSTRUCTOR_NELTS(init);
457 if (!len)
458 return;
459
460 lastval = CONSTRUCTOR_ELT(init, CONSTRUCTOR_NELTS(init) - 1)->value;
461 lastidx = CONSTRUCTOR_ELT(init, CONSTRUCTOR_NELTS(init) - 1)->index;
462
463 for (field = TYPE_FIELDS(TREE_TYPE(decl)); TREE_CHAIN(field); field = TREE_CHAIN(field))
464 ;
465
466 if (lastidx != field)
467 return;
468
469 if (TREE_CODE(lastval) != STRING_CST) {
470 error("Only string constants are supported as initializers "
471 "for randomized structures with flexible arrays");
472 return;
473 }
474
475 flexsize = bitsize_int(TREE_STRING_LENGTH(lastval) *
476 tree_to_uhwi(TYPE_SIZE(TREE_TYPE(TREE_TYPE(lastval)))));
477
478 DECL_SIZE(decl) = size_binop(PLUS_EXPR, TYPE_SIZE(type), flexsize);
479
480 return;
481}
482
483
484static void randomize_layout_finish_decl(void *event_data, void *data)
485{
486 tree decl = (tree)event_data;
487 tree type;
488
489 if (decl == NULL_TREE || decl == error_mark_node)
490 return;
491
492 type = TREE_TYPE(decl);
493
494 if (TREE_CODE(decl) != VAR_DECL)
495 return;
496
497 if (TREE_CODE(type) != RECORD_TYPE && TREE_CODE(type) != UNION_TYPE)
498 return;
499
500 if (!lookup_attribute("randomize_performed", TYPE_ATTRIBUTES(type)))
501 return;
502
503 DECL_SIZE(decl) = 0;
504 DECL_SIZE_UNIT(decl) = 0;
505 SET_DECL_ALIGN(decl, 0);
506 SET_DECL_MODE (decl, VOIDmode);
507 SET_DECL_RTL(decl, 0);
508 update_decl_size(decl);
509 layout_decl(decl, 0);
510}
511
512static void finish_type(void *event_data, void *data)
513{
514 tree type = (tree)event_data;
515
516 if (type == NULL_TREE || type == error_mark_node)
517 return;
518
519 if (TREE_CODE(type) != RECORD_TYPE)
520 return;
521
522 if (TYPE_FIELDS(type) == NULL_TREE)
523 return;
524
525 if (lookup_attribute("randomize_considered", TYPE_ATTRIBUTES(type)))
526 return;
527
528#ifdef __DEBUG_PLUGIN
529 fprintf(stderr, "Calling randomize_type on %s\n", ORIG_TYPE_NAME(type));
530#endif
531#ifdef __DEBUG_VERBOSE
532 debug_tree(type);
533#endif
534 randomize_type(type);
535
536 return;
537}
538
539static struct attribute_spec randomize_layout_attr = { };
540static struct attribute_spec no_randomize_layout_attr = { };
541static struct attribute_spec randomize_considered_attr = { };
542static struct attribute_spec randomize_performed_attr = { };
543
544static void register_attributes(void *event_data, void *data)
545{
546 randomize_layout_attr.name = "randomize_layout";
547 randomize_layout_attr.type_required = true;
548 randomize_layout_attr.handler = handle_randomize_layout_attr;
549 randomize_layout_attr.affects_type_identity = true;
550
551 no_randomize_layout_attr.name = "no_randomize_layout";
552 no_randomize_layout_attr.type_required = true;
553 no_randomize_layout_attr.handler = handle_randomize_layout_attr;
554 no_randomize_layout_attr.affects_type_identity = true;
555
556 randomize_considered_attr.name = "randomize_considered";
557 randomize_considered_attr.type_required = true;
558 randomize_considered_attr.handler = handle_randomize_considered_attr;
559
560 randomize_performed_attr.name = "randomize_performed";
561 randomize_performed_attr.type_required = true;
562 randomize_performed_attr.handler = handle_randomize_performed_attr;
563
564 register_attribute(&randomize_layout_attr);
565 register_attribute(&no_randomize_layout_attr);
566 register_attribute(&randomize_considered_attr);
567 register_attribute(&randomize_performed_attr);
568}
569
570static void check_bad_casts_in_constructor(tree var, tree init)
571{
572 unsigned HOST_WIDE_INT idx;
573 tree field, val;
574 tree field_type, val_type;
575
576 FOR_EACH_CONSTRUCTOR_ELT(CONSTRUCTOR_ELTS(init), idx, field, val) {
577 if (TREE_CODE(val) == CONSTRUCTOR) {
578 check_bad_casts_in_constructor(var, val);
579 continue;
580 }
581
582 /* pipacs' plugin creates franken-arrays that differ from those produced by
583 normal code which all have valid 'field' trees. work around this */
584 if (field == NULL_TREE)
585 continue;
586 field_type = TREE_TYPE(field);
587 val_type = TREE_TYPE(val);
588
589 if (TREE_CODE(field_type) != POINTER_TYPE || TREE_CODE(val_type) != POINTER_TYPE)
590 continue;
591
592 if (field_type == val_type)
593 continue;
594
595 field_type = TYPE_MAIN_VARIANT(strip_array_types(TYPE_MAIN_VARIANT(TREE_TYPE(field_type))));
596 val_type = TYPE_MAIN_VARIANT(strip_array_types(TYPE_MAIN_VARIANT(TREE_TYPE(val_type))));
597
598 if (field_type == void_type_node)
599 continue;
600 if (field_type == val_type)
601 continue;
602 if (TREE_CODE(val_type) != RECORD_TYPE)
603 continue;
604
605 if (!lookup_attribute("randomize_performed", TYPE_ATTRIBUTES(val_type)))
606 continue;
607 MISMATCH(DECL_SOURCE_LOCATION(var), "constructor\n", TYPE_MAIN_VARIANT(field_type), TYPE_MAIN_VARIANT(val_type));
608 }
609}
610
611/* derived from the constify plugin */
612static void check_global_variables(void *event_data, void *data)
613{
614 struct varpool_node *node;
615 tree init;
616
617 FOR_EACH_VARIABLE(node) {
618 tree var = NODE_DECL(node);
619 init = DECL_INITIAL(var);
620 if (init == NULL_TREE)
621 continue;
622
623 if (TREE_CODE(init) != CONSTRUCTOR)
624 continue;
625
626 check_bad_casts_in_constructor(var, init);
627 }
628}
629
630static bool dominated_by_is_err(const_tree rhs, basic_block bb)
631{
632 basic_block dom;
633 gimple dom_stmt;
634 gimple call_stmt;
635 const_tree dom_lhs;
636 const_tree poss_is_err_cond;
637 const_tree poss_is_err_func;
638 const_tree is_err_arg;
639
640 dom = get_immediate_dominator(CDI_DOMINATORS, bb);
641 if (!dom)
642 return false;
643
644 dom_stmt = last_stmt(dom);
645 if (!dom_stmt)
646 return false;
647
648 if (gimple_code(dom_stmt) != GIMPLE_COND)
649 return false;
650
651 if (gimple_cond_code(dom_stmt) != NE_EXPR)
652 return false;
653
654 if (!integer_zerop(gimple_cond_rhs(dom_stmt)))
655 return false;
656
657 poss_is_err_cond = gimple_cond_lhs(dom_stmt);
658
659 if (TREE_CODE(poss_is_err_cond) != SSA_NAME)
660 return false;
661
662 call_stmt = SSA_NAME_DEF_STMT(poss_is_err_cond);
663
664 if (gimple_code(call_stmt) != GIMPLE_CALL)
665 return false;
666
667 dom_lhs = gimple_get_lhs(call_stmt);
668 poss_is_err_func = gimple_call_fndecl(call_stmt);
669 if (!poss_is_err_func)
670 return false;
671 if (dom_lhs != poss_is_err_cond)
672 return false;
673 if (strcmp(DECL_NAME_POINTER(poss_is_err_func), "IS_ERR"))
674 return false;
675
676 is_err_arg = gimple_call_arg(call_stmt, 0);
677 if (!is_err_arg)
678 return false;
679
680 if (is_err_arg != rhs)
681 return false;
682
683 return true;
684}
685
686static void handle_local_var_initializers(void)
687{
688 tree var;
689 unsigned int i;
690
691 FOR_EACH_LOCAL_DECL(cfun, i, var) {
692 tree init = DECL_INITIAL(var);
693 if (!init)
694 continue;
695 if (TREE_CODE(init) != CONSTRUCTOR)
696 continue;
697 check_bad_casts_in_constructor(var, init);
698 }
699}
700
701/*
702 * iterate over all statements to find "bad" casts:
703 * those where the address of the start of a structure is cast
704 * to a pointer of a structure of a different type, or a
705 * structure pointer type is cast to a different structure pointer type
706 */
707static unsigned int find_bad_casts_execute(void)
708{
709 basic_block bb;
710
711 handle_local_var_initializers();
712
713 FOR_EACH_BB_FN(bb, cfun) {
714 gimple_stmt_iterator gsi;
715
716 for (gsi = gsi_start_bb(bb); !gsi_end_p(gsi); gsi_next(&gsi)) {
717 gimple stmt;
718 const_tree lhs;
719 const_tree lhs_type;
720 const_tree rhs1;
721 const_tree rhs_type;
722 const_tree ptr_lhs_type;
723 const_tree ptr_rhs_type;
724 const_tree op0;
725 const_tree op0_type;
726 enum tree_code rhs_code;
727
728 stmt = gsi_stmt(gsi);
729
730#ifdef __DEBUG_PLUGIN
731#ifdef __DEBUG_VERBOSE
732 debug_gimple_stmt(stmt);
733 debug_tree(gimple_get_lhs(stmt));
734#endif
735#endif
736
737 if (gimple_code(stmt) != GIMPLE_ASSIGN)
738 continue;
739
740#ifdef __DEBUG_PLUGIN
741#ifdef __DEBUG_VERBOSE
742 debug_tree(gimple_assign_rhs1(stmt));
743#endif
744#endif
745
746
747 rhs_code = gimple_assign_rhs_code(stmt);
748
749 if (rhs_code != ADDR_EXPR && rhs_code != SSA_NAME)
750 continue;
751
752 lhs = gimple_get_lhs(stmt);
753 lhs_type = TREE_TYPE(lhs);
754 rhs1 = gimple_assign_rhs1(stmt);
755 rhs_type = TREE_TYPE(rhs1);
756
757 if (TREE_CODE(rhs_type) != POINTER_TYPE ||
758 TREE_CODE(lhs_type) != POINTER_TYPE)
759 continue;
760
761 ptr_lhs_type = TYPE_MAIN_VARIANT(strip_array_types(TYPE_MAIN_VARIANT(TREE_TYPE(lhs_type))));
762 ptr_rhs_type = TYPE_MAIN_VARIANT(strip_array_types(TYPE_MAIN_VARIANT(TREE_TYPE(rhs_type))));
763
764 if (ptr_rhs_type == void_type_node)
765 continue;
766
767 if (ptr_lhs_type == void_type_node)
768 continue;
769
770 if (dominated_by_is_err(rhs1, bb))
771 continue;
772
773 if (TREE_CODE(ptr_rhs_type) != RECORD_TYPE) {
774#ifndef __DEBUG_PLUGIN
775 if (lookup_attribute("randomize_performed", TYPE_ATTRIBUTES(ptr_lhs_type)))
776#endif
777 MISMATCH(gimple_location(stmt), "rhs", ptr_lhs_type, ptr_rhs_type);
778 continue;
779 }
780
781 if (rhs_code == SSA_NAME && ptr_lhs_type == ptr_rhs_type)
782 continue;
783
784 if (rhs_code == ADDR_EXPR) {
785 op0 = TREE_OPERAND(rhs1, 0);
786
787 if (op0 == NULL_TREE)
788 continue;
789
790 if (TREE_CODE(op0) != VAR_DECL)
791 continue;
792
793 op0_type = TYPE_MAIN_VARIANT(strip_array_types(TYPE_MAIN_VARIANT(TREE_TYPE(op0))));
794 if (op0_type == ptr_lhs_type)
795 continue;
796
797#ifndef __DEBUG_PLUGIN
798 if (lookup_attribute("randomize_performed", TYPE_ATTRIBUTES(op0_type)))
799#endif
800 MISMATCH(gimple_location(stmt), "op0", ptr_lhs_type, op0_type);
801 } else {
802 const_tree ssa_name_var = SSA_NAME_VAR(rhs1);
803 /* skip bogus type casts introduced by container_of */
804 if (ssa_name_var != NULL_TREE && DECL_NAME(ssa_name_var) &&
805 !strcmp((const char *)DECL_NAME_POINTER(ssa_name_var), "__mptr"))
806 continue;
807#ifndef __DEBUG_PLUGIN
808 if (lookup_attribute("randomize_performed", TYPE_ATTRIBUTES(ptr_rhs_type)))
809#endif
810 MISMATCH(gimple_location(stmt), "ssa", ptr_lhs_type, ptr_rhs_type);
811 }
812
813 }
814 }
815 return 0;
816}
817
818#define PASS_NAME find_bad_casts
819#define NO_GATE
820#define TODO_FLAGS_FINISH TODO_dump_func
821#include "gcc-generate-gimple-pass.h"
822
823__visible int plugin_init(struct plugin_name_args *plugin_info, struct plugin_gcc_version *version)
824{
825 int i;
826 const char * const plugin_name = plugin_info->base_name;
827 const int argc = plugin_info->argc;
828 const struct plugin_argument * const argv = plugin_info->argv;
829 bool enable = true;
830 int obtained_seed = 0;
831 struct register_pass_info find_bad_casts_pass_info;
832
833 find_bad_casts_pass_info.pass = make_find_bad_casts_pass();
834 find_bad_casts_pass_info.reference_pass_name = "ssa";
835 find_bad_casts_pass_info.ref_pass_instance_number = 1;
836 find_bad_casts_pass_info.pos_op = PASS_POS_INSERT_AFTER;
837
838 if (!plugin_default_version_check(version, &gcc_version)) {
839 error(G_("incompatible gcc/plugin versions"));
840 return 1;
841 }
842
843 if (strncmp(lang_hooks.name, "GNU C", 5) && !strncmp(lang_hooks.name, "GNU C+", 6)) {
844 inform(UNKNOWN_LOCATION, G_("%s supports C only, not %s"), plugin_name, lang_hooks.name);
845 enable = false;
846 }
847
848 for (i = 0; i < argc; ++i) {
849 if (!strcmp(argv[i].key, "disable")) {
850 enable = false;
851 continue;
852 }
853 if (!strcmp(argv[i].key, "performance-mode")) {
854 performance_mode = 1;
855 continue;
856 }
857 error(G_("unknown option '-fplugin-arg-%s-%s'"), plugin_name, argv[i].key);
858 }
859
860 if (strlen(randstruct_seed) != 64) {
861 error(G_("invalid seed value supplied for %s plugin"), plugin_name);
862 return 1;
863 }
864 obtained_seed = sscanf(randstruct_seed, "%016llx%016llx%016llx%016llx",
865 &shuffle_seed[0], &shuffle_seed[1], &shuffle_seed[2], &shuffle_seed[3]);
866 if (obtained_seed != 4) {
867 error(G_("Invalid seed supplied for %s plugin"), plugin_name);
868 return 1;
869 }
870
871 register_callback(plugin_name, PLUGIN_INFO, NULL, &randomize_layout_plugin_info);
872 if (enable) {
873 register_callback(plugin_name, PLUGIN_ALL_IPA_PASSES_START, check_global_variables, NULL);
874 register_callback(plugin_name, PLUGIN_PASS_MANAGER_SETUP, NULL, &find_bad_casts_pass_info);
875 register_callback(plugin_name, PLUGIN_FINISH_TYPE, finish_type, NULL);
876 register_callback(plugin_name, PLUGIN_FINISH_DECL, randomize_layout_finish_decl, NULL);
877 }
878 register_callback(plugin_name, PLUGIN_ATTRIBUTES, register_attributes, NULL);
879
880 return 0;
881}