projects / linux-block.git / blame
? search:
summary | shortlog | log | commit | commitdiff | tree
blob | blame (incremental) | history | HEAD
gcc-plugins: randstruct: Only warn about true flexible arrays
[linux-block.git] / scripts / gcc-plugins / randomize_layout_plugin.c
CommitLineData
313dd1b6
KC		 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
34static int performance_mode;
35
36static struct plugin_info randomize_layout_plugin_info = {
d37aa2ef 37 .version = PLUGIN_VERSION,
313dd1b6
KC		 38 .help = "disable\t\t\tdo not activate plugin\n"
39 "performance-mode\tenable cacheline-aware layout randomization\n"
40};
41
313dd1b6
KC		 42/* from old Linux dcache.h */
43static inline unsigned long
44partial_name_hash(unsigned long c, unsigned long prevhash)
45{
46 return (prevhash + (c << 4) + (c >> 4)) * 11;
47}
48static inline unsigned int
49name_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
58static 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 */
101static 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 */
111static 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
122typedef unsigned long long u64;
123
124typedef struct ranctx { u64 a; u64 b; u64 c; u64 d; } ranctx;
125
126#define rot(x,k) (((x)<<(k))|((x)>>(64-(k))))
127static 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
136static 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
148static u64 shuffle_seed[4];
149
150struct partition_group {
151 tree tree_start;
152 unsigned long start;
153 unsigned long length;
154};
155
156static 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
192static void performance_shuffle(tree *newtree, unsigned long length, ranctx *prng_state)
193{
381fdb73 194 unsigned long i, x, index;
313dd1b6
KC		 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);
381fdb73
KC		 200
201 /* FIXME: this group shuffle is currently a no-op. */
313dd1b6
KC		 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++) {
381fdb73 211 for (index = size_group[x].length - 1; index > 0; index--) {
313dd1b6 212 tree tmp;
381fdb73
KC		 213
214 i = size_group[x].start + index;
313dd1b6
KC		 215 if (DECL_BIT_FIELD_TYPE(newtree[i]))
216 continue;
381fdb73
KC		 217 randnum = ranval(prng_state) % (index + 1);
218 randnum += size_group[x].start;
313dd1b6
KC		 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
229static 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 */
243static 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
277static bool is_flexible_array(const_tree field)
278{
279 const_tree fieldtype;
280 const_tree typesize;
313dd1b6
KC		 281
282 fieldtype = TREE_TYPE(field);
283 typesize = TYPE_SIZE(fieldtype);
284
285 if (TREE_CODE(fieldtype) != ARRAY_TYPE)
286 return false;
287
313dd1b6
KC		 288 /* size of type is represented in bits */
289
290 if (typesize == NULL_TREE && TYPE_DOMAIN(fieldtype) != NULL_TREE &&
291 TYPE_MAX_VALUE(TYPE_DOMAIN(fieldtype)) == NULL_TREE)
292 return true;
293
313dd1b6
KC		 294 return false;
295}
296
297static int relayout_struct(tree type)
298{
299 unsigned long num_fields = (unsigned long)list_length(TYPE_FIELDS(type));
300 unsigned long shuffle_length = num_fields;
301 tree field;
302 tree newtree[num_fields];
303 unsigned long i;
304 tree list;
305 tree variant;
306 tree main_variant;
307 expanded_location xloc;
308 bool has_flexarray = false;
309
310 if (TYPE_FIELDS(type) == NULL_TREE)
311 return 0;
312
313 if (num_fields < 2)
314 return 0;
315
316 gcc_assert(TREE_CODE(type) == RECORD_TYPE);
317
318 gcc_assert(num_fields < INT_MAX);
319
320 if (lookup_attribute("randomize_performed", TYPE_ATTRIBUTES(type)) ||
321 lookup_attribute("no_randomize_layout", TYPE_ATTRIBUTES(TYPE_MAIN_VARIANT(type))))
322 return 0;
323
324 /* Workaround for 3rd-party VirtualBox source that we can't modify ourselves */
325 if (!strcmp((const char *)ORIG_TYPE_NAME(type), "INTNETTRUNKFACTORY") ||
326 !strcmp((const char *)ORIG_TYPE_NAME(type), "RAWPCIFACTORY"))
327 return 0;
328
329 /* throw out any structs in uapi */
330 xloc = expand_location(DECL_SOURCE_LOCATION(TYPE_FIELDS(type)));
331
332 if (strstr(xloc.file, "/uapi/"))
333 error(G_("attempted to randomize userland API struct %s"), ORIG_TYPE_NAME(type));
334
335 for (field = TYPE_FIELDS(type), i = 0; field; field = TREE_CHAIN(field), i++) {
336 gcc_assert(TREE_CODE(field) == FIELD_DECL);
337 newtree[i] = field;
338 }
339
340 /*
341 * enforce that we don't randomize the layout of the last
342 * element of a struct if it's a 0 or 1-length array
343 * or a proper flexible array
344 */
345 if (is_flexible_array(newtree[num_fields - 1])) {
346 has_flexarray = true;
347 shuffle_length--;
348 }
349
350 shuffle(type, (tree *)newtree, shuffle_length);
351
352 /*
353 * set up a bogus anonymous struct field designed to error out on unnamed struct initializers
354 * as gcc provides no other way to detect such code
355 */
356 list = make_node(FIELD_DECL);
357 TREE_CHAIN(list) = newtree[0];
358 TREE_TYPE(list) = void_type_node;
359 DECL_SIZE(list) = bitsize_zero_node;
360 DECL_NONADDRESSABLE_P(list) = 1;
361 DECL_FIELD_BIT_OFFSET(list) = bitsize_zero_node;
362 DECL_SIZE_UNIT(list) = size_zero_node;
363 DECL_FIELD_OFFSET(list) = size_zero_node;
364 DECL_CONTEXT(list) = type;
365 // to satisfy the constify plugin
366 TREE_READONLY(list) = 1;
367
368 for (i = 0; i < num_fields - 1; i++)
369 TREE_CHAIN(newtree[i]) = newtree[i+1];
370 TREE_CHAIN(newtree[num_fields - 1]) = NULL_TREE;
371
372 main_variant = TYPE_MAIN_VARIANT(type);
373 for (variant = main_variant; variant; variant = TYPE_NEXT_VARIANT(variant)) {
374 TYPE_FIELDS(variant) = list;
375 TYPE_ATTRIBUTES(variant) = copy_list(TYPE_ATTRIBUTES(variant));
376 TYPE_ATTRIBUTES(variant) = tree_cons(get_identifier("randomize_performed"), NULL_TREE, TYPE_ATTRIBUTES(variant));
377 TYPE_ATTRIBUTES(variant) = tree_cons(get_identifier("designated_init"), NULL_TREE, TYPE_ATTRIBUTES(variant));
378 if (has_flexarray)
379 TYPE_ATTRIBUTES(type) = tree_cons(get_identifier("has_flexarray"), NULL_TREE, TYPE_ATTRIBUTES(type));
380 }
381
382 /*
383 * force a re-layout of the main variant
384 * the TYPE_SIZE for all variants will be recomputed
385 * by finalize_type_size()
386 */
387 TYPE_SIZE(main_variant) = NULL_TREE;
388 layout_type(main_variant);
389 gcc_assert(TYPE_SIZE(main_variant) != NULL_TREE);
390
391 return 1;
392}
393
394/* from constify plugin */
395static const_tree get_field_type(const_tree field)
396{
397 return strip_array_types(TREE_TYPE(field));
398}
399
400/* from constify plugin */
401static bool is_fptr(const_tree fieldtype)
402{
403 if (TREE_CODE(fieldtype) != POINTER_TYPE)
404 return false;
405
406 return TREE_CODE(TREE_TYPE(fieldtype)) == FUNCTION_TYPE;
407}
408
409/* derived from constify plugin */
410static int is_pure_ops_struct(const_tree node)
411{
412 const_tree field;
413
414 gcc_assert(TREE_CODE(node) == RECORD_TYPE || TREE_CODE(node) == UNION_TYPE);
415
313dd1b6
KC		 416 for (field = TYPE_FIELDS(node); field; field = TREE_CHAIN(field)) {
417 const_tree fieldtype = get_field_type(field);
418 enum tree_code code = TREE_CODE(fieldtype);
419
420 if (node == fieldtype)
421 continue;
422
60f2c82e
JK		 423 if (code == RECORD_TYPE || code == UNION_TYPE) {
424 if (!is_pure_ops_struct(fieldtype))
425 return 0;
313dd1b6 426 continue;
60f2c82e 427 }
313dd1b6 428
60f2c82e 429 if (!is_fptr(fieldtype))
313dd1b6
KC		 430 return 0;
431 }
432
433 return 1;
434}
435
436static void randomize_type(tree type)
437{
438 tree variant;
439
440 gcc_assert(TREE_CODE(type) == RECORD_TYPE);
441
442 if (lookup_attribute("randomize_considered", TYPE_ATTRIBUTES(type)))
443 return;
444
445 if (lookup_attribute("randomize_layout", TYPE_ATTRIBUTES(TYPE_MAIN_VARIANT(type))) || is_pure_ops_struct(type))
446 relayout_struct(type);
447
448 for (variant = TYPE_MAIN_VARIANT(type); variant; variant = TYPE_NEXT_VARIANT(variant)) {
449 TYPE_ATTRIBUTES(type) = copy_list(TYPE_ATTRIBUTES(type));
450 TYPE_ATTRIBUTES(type) = tree_cons(get_identifier("randomize_considered"), NULL_TREE, TYPE_ATTRIBUTES(type));
451 }
452#ifdef __DEBUG_PLUGIN
453 fprintf(stderr, "Marking randomize_considered on struct %s\n", ORIG_TYPE_NAME(type));
454#ifdef __DEBUG_VERBOSE
455 debug_tree(type);
456#endif
457#endif
458}
459
460static void update_decl_size(tree decl)
461{
462 tree lastval, lastidx, field, init, type, flexsize;
463 unsigned HOST_WIDE_INT len;
464
465 type = TREE_TYPE(decl);
466
467 if (!lookup_attribute("has_flexarray", TYPE_ATTRIBUTES(type)))
468 return;
469
470 init = DECL_INITIAL(decl);
471 if (init == NULL_TREE || init == error_mark_node)
472 return;
473
474 if (TREE_CODE(init) != CONSTRUCTOR)
475 return;
476
477 len = CONSTRUCTOR_NELTS(init);
478 if (!len)
479 return;
480
481 lastval = CONSTRUCTOR_ELT(init, CONSTRUCTOR_NELTS(init) - 1)->value;
482 lastidx = CONSTRUCTOR_ELT(init, CONSTRUCTOR_NELTS(init) - 1)->index;
483
484 for (field = TYPE_FIELDS(TREE_TYPE(decl)); TREE_CHAIN(field); field = TREE_CHAIN(field))
485 ;
486
487 if (lastidx != field)
488 return;
489
490 if (TREE_CODE(lastval) != STRING_CST) {
491 error("Only string constants are supported as initializers "
492 "for randomized structures with flexible arrays");
493 return;
494 }
495
496 flexsize = bitsize_int(TREE_STRING_LENGTH(lastval) *
497 tree_to_uhwi(TYPE_SIZE(TREE_TYPE(TREE_TYPE(lastval)))));
498
499 DECL_SIZE(decl) = size_binop(PLUS_EXPR, TYPE_SIZE(type), flexsize);
500
501 return;
502}
503
504
505static void randomize_layout_finish_decl(void *event_data, void *data)
506{
507 tree decl = (tree)event_data;
508 tree type;
509
510 if (decl == NULL_TREE || decl == error_mark_node)
511 return;
512
513 type = TREE_TYPE(decl);
514
515 if (TREE_CODE(decl) != VAR_DECL)
516 return;
517
518 if (TREE_CODE(type) != RECORD_TYPE && TREE_CODE(type) != UNION_TYPE)
519 return;
520
521 if (!lookup_attribute("randomize_performed", TYPE_ATTRIBUTES(type)))
522 return;
523
524 DECL_SIZE(decl) = 0;
525 DECL_SIZE_UNIT(decl) = 0;
526 SET_DECL_ALIGN(decl, 0);
527 SET_DECL_MODE (decl, VOIDmode);
528 SET_DECL_RTL(decl, 0);
529 update_decl_size(decl);
530 layout_decl(decl, 0);
531}
532
533static void finish_type(void *event_data, void *data)
534{
535 tree type = (tree)event_data;
536
537 if (type == NULL_TREE || type == error_mark_node)
538 return;
539
540 if (TREE_CODE(type) != RECORD_TYPE)
541 return;
542
543 if (TYPE_FIELDS(type) == NULL_TREE)
544 return;
545
546 if (lookup_attribute("randomize_considered", TYPE_ATTRIBUTES(type)))
547 return;
548
549#ifdef __DEBUG_PLUGIN
550 fprintf(stderr, "Calling randomize_type on %s\n", ORIG_TYPE_NAME(type));
551#endif
552#ifdef __DEBUG_VERBOSE
553 debug_tree(type);
554#endif
555 randomize_type(type);
556
557 return;
558}
559
b8672910
KC		 560static struct attribute_spec randomize_layout_attr = { };
561static struct attribute_spec no_randomize_layout_attr = { };
562static struct attribute_spec randomize_considered_attr = { };
563static struct attribute_spec randomize_performed_attr = { };
313dd1b6 564
b8672910
KC		 565static void register_attributes(void *event_data, void *data)
566{
567 randomize_layout_attr.name = "randomize_layout";
568 randomize_layout_attr.type_required = true;
569 randomize_layout_attr.handler = handle_randomize_layout_attr;
b8672910 570 randomize_layout_attr.affects_type_identity = true;
313dd1b6 571
b8672910
KC		 572 no_randomize_layout_attr.name = "no_randomize_layout";
573 no_randomize_layout_attr.type_required = true;
574 no_randomize_layout_attr.handler = handle_randomize_layout_attr;
b8672910 575 no_randomize_layout_attr.affects_type_identity = true;
313dd1b6 576
b8672910
KC		 577 randomize_considered_attr.name = "randomize_considered";
578 randomize_considered_attr.type_required = true;
579 randomize_considered_attr.handler = handle_randomize_considered_attr;
580
581 randomize_performed_attr.name = "randomize_performed";
582 randomize_performed_attr.type_required = true;
583 randomize_performed_attr.handler = handle_randomize_performed_attr;
313dd1b6 584
313dd1b6
KC		 585 register_attribute(&randomize_layout_attr);
586 register_attribute(&no_randomize_layout_attr);
587 register_attribute(&randomize_considered_attr);
588 register_attribute(&randomize_performed_attr);
589}
590
591static void check_bad_casts_in_constructor(tree var, tree init)
592{
593 unsigned HOST_WIDE_INT idx;
594 tree field, val;
595 tree field_type, val_type;
596
597 FOR_EACH_CONSTRUCTOR_ELT(CONSTRUCTOR_ELTS(init), idx, field, val) {
598 if (TREE_CODE(val) == CONSTRUCTOR) {
599 check_bad_casts_in_constructor(var, val);
600 continue;
601 }
602
603 /* pipacs' plugin creates franken-arrays that differ from those produced by
604 normal code which all have valid 'field' trees. work around this */
605 if (field == NULL_TREE)
606 continue;
607 field_type = TREE_TYPE(field);
608 val_type = TREE_TYPE(val);
609
610 if (TREE_CODE(field_type) != POINTER_TYPE || TREE_CODE(val_type) != POINTER_TYPE)
611 continue;
612
613 if (field_type == val_type)
614 continue;
615
616 field_type = TYPE_MAIN_VARIANT(strip_array_types(TYPE_MAIN_VARIANT(TREE_TYPE(field_type))));
617 val_type = TYPE_MAIN_VARIANT(strip_array_types(TYPE_MAIN_VARIANT(TREE_TYPE(val_type))));
618
619 if (field_type == void_type_node)
620 continue;
621 if (field_type == val_type)
622 continue;
623 if (TREE_CODE(val_type) != RECORD_TYPE)
624 continue;
625
626 if (!lookup_attribute("randomize_performed", TYPE_ATTRIBUTES(val_type)))
627 continue;
628 MISMATCH(DECL_SOURCE_LOCATION(var), "constructor\n", TYPE_MAIN_VARIANT(field_type), TYPE_MAIN_VARIANT(val_type));
629 }
630}
631
632/* derived from the constify plugin */
633static void check_global_variables(void *event_data, void *data)
634{
635 struct varpool_node *node;
636 tree init;
637
638 FOR_EACH_VARIABLE(node) {
639 tree var = NODE_DECL(node);
640 init = DECL_INITIAL(var);
641 if (init == NULL_TREE)
642 continue;
643
644 if (TREE_CODE(init) != CONSTRUCTOR)
645 continue;
646
647 check_bad_casts_in_constructor(var, init);
648 }
649}
650
651static bool dominated_by_is_err(const_tree rhs, basic_block bb)
652{
653 basic_block dom;
654 gimple dom_stmt;
655 gimple call_stmt;
656 const_tree dom_lhs;
657 const_tree poss_is_err_cond;
658 const_tree poss_is_err_func;
659 const_tree is_err_arg;
660
661 dom = get_immediate_dominator(CDI_DOMINATORS, bb);
662 if (!dom)
663 return false;
664
665 dom_stmt = last_stmt(dom);
666 if (!dom_stmt)
667 return false;
668
669 if (gimple_code(dom_stmt) != GIMPLE_COND)
670 return false;
671
672 if (gimple_cond_code(dom_stmt) != NE_EXPR)
673 return false;
674
675 if (!integer_zerop(gimple_cond_rhs(dom_stmt)))
676 return false;
677
678 poss_is_err_cond = gimple_cond_lhs(dom_stmt);
679
680 if (TREE_CODE(poss_is_err_cond) != SSA_NAME)
681 return false;
682
683 call_stmt = SSA_NAME_DEF_STMT(poss_is_err_cond);
684
685 if (gimple_code(call_stmt) != GIMPLE_CALL)
686 return false;
687
688 dom_lhs = gimple_get_lhs(call_stmt);
689 poss_is_err_func = gimple_call_fndecl(call_stmt);
690 if (!poss_is_err_func)
691 return false;
692 if (dom_lhs != poss_is_err_cond)
693 return false;
694 if (strcmp(DECL_NAME_POINTER(poss_is_err_func), "IS_ERR"))
695 return false;
696
697 is_err_arg = gimple_call_arg(call_stmt, 0);
698 if (!is_err_arg)
699 return false;
700
701 if (is_err_arg != rhs)
702 return false;
703
704 return true;
705}
706
707static void handle_local_var_initializers(void)
708{
709 tree var;
710 unsigned int i;
711
712 FOR_EACH_LOCAL_DECL(cfun, i, var) {
713 tree init = DECL_INITIAL(var);
714 if (!init)
715 continue;
716 if (TREE_CODE(init) != CONSTRUCTOR)
717 continue;
718 check_bad_casts_in_constructor(var, init);
719 }
720}
721
313dd1b6
KC		 722/*
723 * iterate over all statements to find "bad" casts:
724 * those where the address of the start of a structure is cast
725 * to a pointer of a structure of a different type, or a
726 * structure pointer type is cast to a different structure pointer type
727 */
728static unsigned int find_bad_casts_execute(void)
729{
730 basic_block bb;
731
732 handle_local_var_initializers();
733
734 FOR_EACH_BB_FN(bb, cfun) {
735 gimple_stmt_iterator gsi;
736
737 for (gsi = gsi_start_bb(bb); !gsi_end_p(gsi); gsi_next(&gsi)) {
738 gimple stmt;
739 const_tree lhs;
740 const_tree lhs_type;
741 const_tree rhs1;
742 const_tree rhs_type;
743 const_tree ptr_lhs_type;
744 const_tree ptr_rhs_type;
745 const_tree op0;
746 const_tree op0_type;
747 enum tree_code rhs_code;
748
749 stmt = gsi_stmt(gsi);
750
751#ifdef __DEBUG_PLUGIN
752#ifdef __DEBUG_VERBOSE
753 debug_gimple_stmt(stmt);
754 debug_tree(gimple_get_lhs(stmt));
755#endif
756#endif
757
758 if (gimple_code(stmt) != GIMPLE_ASSIGN)
759 continue;
760
761#ifdef __DEBUG_PLUGIN
762#ifdef __DEBUG_VERBOSE
763 debug_tree(gimple_assign_rhs1(stmt));
764#endif
765#endif
766
767
768 rhs_code = gimple_assign_rhs_code(stmt);
769
770 if (rhs_code != ADDR_EXPR && rhs_code != SSA_NAME)
771 continue;
772
773 lhs = gimple_get_lhs(stmt);
774 lhs_type = TREE_TYPE(lhs);
775 rhs1 = gimple_assign_rhs1(stmt);
776 rhs_type = TREE_TYPE(rhs1);
777
778 if (TREE_CODE(rhs_type) != POINTER_TYPE ||
779 TREE_CODE(lhs_type) != POINTER_TYPE)
780 continue;
781
782 ptr_lhs_type = TYPE_MAIN_VARIANT(strip_array_types(TYPE_MAIN_VARIANT(TREE_TYPE(lhs_type))));
783 ptr_rhs_type = TYPE_MAIN_VARIANT(strip_array_types(TYPE_MAIN_VARIANT(TREE_TYPE(rhs_type))));
784
785 if (ptr_rhs_type == void_type_node)
786 continue;
787
788 if (ptr_lhs_type == void_type_node)
789 continue;
790
791 if (dominated_by_is_err(rhs1, bb))
792 continue;
793
794 if (TREE_CODE(ptr_rhs_type) != RECORD_TYPE) {
795#ifndef __DEBUG_PLUGIN
796 if (lookup_attribute("randomize_performed", TYPE_ATTRIBUTES(ptr_lhs_type)))
797#endif
710e4ebf 798 MISMATCH(gimple_location(stmt), "rhs", ptr_lhs_type, ptr_rhs_type);
313dd1b6
KC		 799 continue;
800 }
801
802 if (rhs_code == SSA_NAME && ptr_lhs_type == ptr_rhs_type)
803 continue;
804
805 if (rhs_code == ADDR_EXPR) {
806 op0 = TREE_OPERAND(rhs1, 0);
807
808 if (op0 == NULL_TREE)
809 continue;
810
811 if (TREE_CODE(op0) != VAR_DECL)
812 continue;
813
814 op0_type = TYPE_MAIN_VARIANT(strip_array_types(TYPE_MAIN_VARIANT(TREE_TYPE(op0))));
815 if (op0_type == ptr_lhs_type)
816 continue;
817
818#ifndef __DEBUG_PLUGIN
819 if (lookup_attribute("randomize_performed", TYPE_ATTRIBUTES(op0_type)))
820#endif
710e4ebf 821 MISMATCH(gimple_location(stmt), "op0", ptr_lhs_type, op0_type);
313dd1b6
KC		 822 } else {
823 const_tree ssa_name_var = SSA_NAME_VAR(rhs1);
824 /* skip bogus type casts introduced by container_of */
825 if (ssa_name_var != NULL_TREE && DECL_NAME(ssa_name_var) &&
826 !strcmp((const char *)DECL_NAME_POINTER(ssa_name_var), "__mptr"))
827 continue;
828#ifndef __DEBUG_PLUGIN
829 if (lookup_attribute("randomize_performed", TYPE_ATTRIBUTES(ptr_rhs_type)))
830#endif
710e4ebf 831 MISMATCH(gimple_location(stmt), "ssa", ptr_lhs_type, ptr_rhs_type);
313dd1b6
KC		 832 }
833
834 }
835 }
836 return 0;
837}
838
839#define PASS_NAME find_bad_casts
840#define NO_GATE
841#define TODO_FLAGS_FINISH TODO_dump_func
842#include "gcc-generate-gimple-pass.h"
843
844__visible int plugin_init(struct plugin_name_args *plugin_info, struct plugin_gcc_version *version)
845{
846 int i;
847 const char * const plugin_name = plugin_info->base_name;
848 const int argc = plugin_info->argc;
849 const struct plugin_argument * const argv = plugin_info->argv;
850 bool enable = true;
851 int obtained_seed = 0;
852 struct register_pass_info find_bad_casts_pass_info;
853
854 find_bad_casts_pass_info.pass = make_find_bad_casts_pass();
855 find_bad_casts_pass_info.reference_pass_name = "ssa";
856 find_bad_casts_pass_info.ref_pass_instance_number = 1;
857 find_bad_casts_pass_info.pos_op = PASS_POS_INSERT_AFTER;
858
859 if (!plugin_default_version_check(version, &gcc_version)) {
860 error(G_("incompatible gcc/plugin versions"));
861 return 1;
862 }
863
864 if (strncmp(lang_hooks.name, "GNU C", 5) && !strncmp(lang_hooks.name, "GNU C+", 6)) {
865 inform(UNKNOWN_LOCATION, G_("%s supports C only, not %s"), plugin_name, lang_hooks.name);
866 enable = false;
867 }
868
869 for (i = 0; i < argc; ++i) {
870 if (!strcmp(argv[i].key, "disable")) {
871 enable = false;
872 continue;
873 }
874 if (!strcmp(argv[i].key, "performance-mode")) {
875 performance_mode = 1;
876 continue;
877 }
878 error(G_("unknown option '-fplugin-arg-%s-%s'"), plugin_name, argv[i].key);
879 }
880
881 if (strlen(randstruct_seed) != 64) {
882 error(G_("invalid seed value supplied for %s plugin"), plugin_name);
883 return 1;
884 }
885 obtained_seed = sscanf(randstruct_seed, "%016llx%016llx%016llx%016llx",
886 &shuffle_seed[0], &shuffle_seed[1], &shuffle_seed[2], &shuffle_seed[3]);
887 if (obtained_seed != 4) {
888 error(G_("Invalid seed supplied for %s plugin"), plugin_name);
889 return 1;
890 }
891
892 register_callback(plugin_name, PLUGIN_INFO, NULL, &randomize_layout_plugin_info);
893 if (enable) {
894 register_callback(plugin_name, PLUGIN_ALL_IPA_PASSES_START, check_global_variables, NULL);
895 register_callback(plugin_name, PLUGIN_PASS_MANAGER_SETUP, NULL, &find_bad_casts_pass_info);
896 register_callback(plugin_name, PLUGIN_FINISH_TYPE, finish_type, NULL);
897 register_callback(plugin_name, PLUGIN_FINISH_DECL, randomize_layout_finish_decl, NULL);
898 }
899 register_callback(plugin_name, PLUGIN_ATTRIBUTES, register_attributes, NULL);
900
901 return 0;
902}
Linux 6.x block layer and io_uring tree(s)