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