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