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gcc-plugins: Add the randstruct plugin
[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 = {
37 .version = "201402201816vanilla",
38 .help = "disable\t\t\tdo not activate plugin\n"
39 "performance-mode\tenable cacheline-aware layout randomization\n"
40};
41
42struct whitelist_entry {
43 const char *pathname;
44 const char *lhs;
45 const char *rhs;
46};
47
48static const struct whitelist_entry whitelist[] = {
49 { }
50};
51
52/* from old Linux dcache.h */
53static inline unsigned long
54partial_name_hash(unsigned long c, unsigned long prevhash)
55{
56 return (prevhash + (c << 4) + (c >> 4)) * 11;
57}
58static inline unsigned int
59name_hash(const unsigned char *name)
60{
61 unsigned long hash = 0;
62 unsigned int len = strlen((const char *)name);
63 while (len--)
64 hash = partial_name_hash(*name++, hash);
65 return (unsigned int)hash;
66}
67
68static tree handle_randomize_layout_attr(tree *node, tree name, tree args, int flags, bool *no_add_attrs)
69{
70 tree type;
71
72 *no_add_attrs = true;
73 if (TREE_CODE(*node) == FUNCTION_DECL) {
74 error("%qE attribute does not apply to functions (%qF)", name, *node);
75 return NULL_TREE;
76 }
77
78 if (TREE_CODE(*node) == PARM_DECL) {
79 error("%qE attribute does not apply to function parameters (%qD)", name, *node);
80 return NULL_TREE;
81 }
82
83 if (TREE_CODE(*node) == VAR_DECL) {
84 error("%qE attribute does not apply to variables (%qD)", name, *node);
85 return NULL_TREE;
86 }
87
88 if (TYPE_P(*node)) {
89 type = *node;
90 } else {
91 gcc_assert(TREE_CODE(*node) == TYPE_DECL);
92 type = TREE_TYPE(*node);
93 }
94
95 if (TREE_CODE(type) != RECORD_TYPE) {
96 error("%qE attribute used on %qT applies to struct types only", name, type);
97 return NULL_TREE;
98 }
99
100 if (lookup_attribute(IDENTIFIER_POINTER(name), TYPE_ATTRIBUTES(type))) {
101 error("%qE attribute is already applied to the type %qT", name, type);
102 return NULL_TREE;
103 }
104
105 *no_add_attrs = false;
106
107 return NULL_TREE;
108}
109
110/* set on complete types that we don't need to inspect further at all */
111static tree handle_randomize_considered_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 * set on types that we've performed a shuffle on, to prevent re-shuffling
119 * this does not preclude us from inspecting its fields for potential shuffles
120 */
121static tree handle_randomize_performed_attr(tree *node, tree name, tree args, int flags, bool *no_add_attrs)
122{
123 *no_add_attrs = false;
124 return NULL_TREE;
125}
126
127/*
128 * 64bit variant of Bob Jenkins' public domain PRNG
129 * 256 bits of internal state
130 */
131
132typedef unsigned long long u64;
133
134typedef struct ranctx { u64 a; u64 b; u64 c; u64 d; } ranctx;
135
136#define rot(x,k) (((x)<<(k))|((x)>>(64-(k))))
137static u64 ranval(ranctx *x) {
138 u64 e = x->a - rot(x->b, 7);
139 x->a = x->b ^ rot(x->c, 13);
140 x->b = x->c + rot(x->d, 37);
141 x->c = x->d + e;
142 x->d = e + x->a;
143 return x->d;
144}
145
146static void raninit(ranctx *x, u64 *seed) {
147 int i;
148
149 x->a = seed[0];
150 x->b = seed[1];
151 x->c = seed[2];
152 x->d = seed[3];
153
154 for (i=0; i < 30; ++i)
155 (void)ranval(x);
156}
157
158static u64 shuffle_seed[4];
159
160struct partition_group {
161 tree tree_start;
162 unsigned long start;
163 unsigned long length;
164};
165
166static void partition_struct(tree *fields, unsigned long length, struct partition_group *size_groups, unsigned long *num_groups)
167{
168 unsigned long i;
169 unsigned long accum_size = 0;
170 unsigned long accum_length = 0;
171 unsigned long group_idx = 0;
172
173 gcc_assert(length < INT_MAX);
174
175 memset(size_groups, 0, sizeof(struct partition_group) * length);
176
177 for (i = 0; i < length; i++) {
178 if (size_groups[group_idx].tree_start == NULL_TREE) {
179 size_groups[group_idx].tree_start = fields[i];
180 size_groups[group_idx].start = i;
181 accum_length = 0;
182 accum_size = 0;
183 }
184 accum_size += (unsigned long)int_size_in_bytes(TREE_TYPE(fields[i]));
185 accum_length++;
186 if (accum_size >= 64) {
187 size_groups[group_idx].length = accum_length;
188 accum_length = 0;
189 group_idx++;
190 }
191 }
192
193 if (size_groups[group_idx].tree_start != NULL_TREE &&
194 !size_groups[group_idx].length) {
195 size_groups[group_idx].length = accum_length;
196 group_idx++;
197 }
198
199 *num_groups = group_idx;
200}
201
202static void performance_shuffle(tree *newtree, unsigned long length, ranctx *prng_state)
203{
204 unsigned long i, x;
205 struct partition_group size_group[length];
206 unsigned long num_groups = 0;
207 unsigned long randnum;
208
209 partition_struct(newtree, length, (struct partition_group *)&size_group, &num_groups);
210 for (i = num_groups - 1; i > 0; i--) {
211 struct partition_group tmp;
212 randnum = ranval(prng_state) % (i + 1);
213 tmp = size_group[i];
214 size_group[i] = size_group[randnum];
215 size_group[randnum] = tmp;
216 }
217
218 for (x = 0; x < num_groups; x++) {
219 for (i = size_group[x].start + size_group[x].length - 1; i > size_group[x].start; i--) {
220 tree tmp;
221 if (DECL_BIT_FIELD_TYPE(newtree[i]))
222 continue;
223 randnum = ranval(prng_state) % (i + 1);
224 // we could handle this case differently if desired
225 if (DECL_BIT_FIELD_TYPE(newtree[randnum]))
226 continue;
227 tmp = newtree[i];
228 newtree[i] = newtree[randnum];
229 newtree[randnum] = tmp;
230 }
231 }
232}
233
234static void full_shuffle(tree *newtree, unsigned long length, ranctx *prng_state)
235{
236 unsigned long i, randnum;
237
238 for (i = length - 1; i > 0; i--) {
239 tree tmp;
240 randnum = ranval(prng_state) % (i + 1);
241 tmp = newtree[i];
242 newtree[i] = newtree[randnum];
243 newtree[randnum] = tmp;
244 }
245}
246
247/* modern in-place Fisher-Yates shuffle */
248static void shuffle(const_tree type, tree *newtree, unsigned long length)
249{
250 unsigned long i;
251 u64 seed[4];
252 ranctx prng_state;
253 const unsigned char *structname;
254
255 if (length == 0)
256 return;
257
258 gcc_assert(TREE_CODE(type) == RECORD_TYPE);
259
260 structname = ORIG_TYPE_NAME(type);
261
262#ifdef __DEBUG_PLUGIN
263 fprintf(stderr, "Shuffling struct %s %p\n", (const char *)structname, type);
264#ifdef __DEBUG_VERBOSE
265 debug_tree((tree)type);
266#endif
267#endif
268
269 for (i = 0; i < 4; i++) {
270 seed[i] = shuffle_seed[i];
271 seed[i] ^= name_hash(structname);
272 }
273
274 raninit(&prng_state, (u64 *)&seed);
275
276 if (performance_mode)
277 performance_shuffle(newtree, length, &prng_state);
278 else
279 full_shuffle(newtree, length, &prng_state);
280}
281
282static bool is_flexible_array(const_tree field)
283{
284 const_tree fieldtype;
285 const_tree typesize;
286 const_tree elemtype;
287 const_tree elemsize;
288
289 fieldtype = TREE_TYPE(field);
290 typesize = TYPE_SIZE(fieldtype);
291
292 if (TREE_CODE(fieldtype) != ARRAY_TYPE)
293 return false;
294
295 elemtype = TREE_TYPE(fieldtype);
296 elemsize = TYPE_SIZE(elemtype);
297
298 /* size of type is represented in bits */
299
300 if (typesize == NULL_TREE && TYPE_DOMAIN(fieldtype) != NULL_TREE &&
301 TYPE_MAX_VALUE(TYPE_DOMAIN(fieldtype)) == NULL_TREE)
302 return true;
303
304 if (typesize != NULL_TREE &&
305 (TREE_CONSTANT(typesize) && (!tree_to_uhwi(typesize) ||
306 tree_to_uhwi(typesize) == tree_to_uhwi(elemsize))))
307 return true;
308
309 return false;
310}
311
312static int relayout_struct(tree type)
313{
314 unsigned long num_fields = (unsigned long)list_length(TYPE_FIELDS(type));
315 unsigned long shuffle_length = num_fields;
316 tree field;
317 tree newtree[num_fields];
318 unsigned long i;
319 tree list;
320 tree variant;
321 tree main_variant;
322 expanded_location xloc;
323 bool has_flexarray = false;
324
325 if (TYPE_FIELDS(type) == NULL_TREE)
326 return 0;
327
328 if (num_fields < 2)
329 return 0;
330
331 gcc_assert(TREE_CODE(type) == RECORD_TYPE);
332
333 gcc_assert(num_fields < INT_MAX);
334
335 if (lookup_attribute("randomize_performed", TYPE_ATTRIBUTES(type)) ||
336 lookup_attribute("no_randomize_layout", TYPE_ATTRIBUTES(TYPE_MAIN_VARIANT(type))))
337 return 0;
338
339 /* Workaround for 3rd-party VirtualBox source that we can't modify ourselves */
340 if (!strcmp((const char *)ORIG_TYPE_NAME(type), "INTNETTRUNKFACTORY") ||
341 !strcmp((const char *)ORIG_TYPE_NAME(type), "RAWPCIFACTORY"))
342 return 0;
343
344 /* throw out any structs in uapi */
345 xloc = expand_location(DECL_SOURCE_LOCATION(TYPE_FIELDS(type)));
346
347 if (strstr(xloc.file, "/uapi/"))
348 error(G_("attempted to randomize userland API struct %s"), ORIG_TYPE_NAME(type));
349
350 for (field = TYPE_FIELDS(type), i = 0; field; field = TREE_CHAIN(field), i++) {
351 gcc_assert(TREE_CODE(field) == FIELD_DECL);
352 newtree[i] = field;
353 }
354
355 /*
356 * enforce that we don't randomize the layout of the last
357 * element of a struct if it's a 0 or 1-length array
358 * or a proper flexible array
359 */
360 if (is_flexible_array(newtree[num_fields - 1])) {
361 has_flexarray = true;
362 shuffle_length--;
363 }
364
365 shuffle(type, (tree *)newtree, shuffle_length);
366
367 /*
368 * set up a bogus anonymous struct field designed to error out on unnamed struct initializers
369 * as gcc provides no other way to detect such code
370 */
371 list = make_node(FIELD_DECL);
372 TREE_CHAIN(list) = newtree[0];
373 TREE_TYPE(list) = void_type_node;
374 DECL_SIZE(list) = bitsize_zero_node;
375 DECL_NONADDRESSABLE_P(list) = 1;
376 DECL_FIELD_BIT_OFFSET(list) = bitsize_zero_node;
377 DECL_SIZE_UNIT(list) = size_zero_node;
378 DECL_FIELD_OFFSET(list) = size_zero_node;
379 DECL_CONTEXT(list) = type;
380 // to satisfy the constify plugin
381 TREE_READONLY(list) = 1;
382
383 for (i = 0; i < num_fields - 1; i++)
384 TREE_CHAIN(newtree[i]) = newtree[i+1];
385 TREE_CHAIN(newtree[num_fields - 1]) = NULL_TREE;
386
387 main_variant = TYPE_MAIN_VARIANT(type);
388 for (variant = main_variant; variant; variant = TYPE_NEXT_VARIANT(variant)) {
389 TYPE_FIELDS(variant) = list;
390 TYPE_ATTRIBUTES(variant) = copy_list(TYPE_ATTRIBUTES(variant));
391 TYPE_ATTRIBUTES(variant) = tree_cons(get_identifier("randomize_performed"), NULL_TREE, TYPE_ATTRIBUTES(variant));
392 TYPE_ATTRIBUTES(variant) = tree_cons(get_identifier("designated_init"), NULL_TREE, TYPE_ATTRIBUTES(variant));
393 if (has_flexarray)
394 TYPE_ATTRIBUTES(type) = tree_cons(get_identifier("has_flexarray"), NULL_TREE, TYPE_ATTRIBUTES(type));
395 }
396
397 /*
398 * force a re-layout of the main variant
399 * the TYPE_SIZE for all variants will be recomputed
400 * by finalize_type_size()
401 */
402 TYPE_SIZE(main_variant) = NULL_TREE;
403 layout_type(main_variant);
404 gcc_assert(TYPE_SIZE(main_variant) != NULL_TREE);
405
406 return 1;
407}
408
409/* from constify plugin */
410static const_tree get_field_type(const_tree field)
411{
412 return strip_array_types(TREE_TYPE(field));
413}
414
415/* from constify plugin */
416static bool is_fptr(const_tree fieldtype)
417{
418 if (TREE_CODE(fieldtype) != POINTER_TYPE)
419 return false;
420
421 return TREE_CODE(TREE_TYPE(fieldtype)) == FUNCTION_TYPE;
422}
423
424/* derived from constify plugin */
425static int is_pure_ops_struct(const_tree node)
426{
427 const_tree field;
428
429 gcc_assert(TREE_CODE(node) == RECORD_TYPE || TREE_CODE(node) == UNION_TYPE);
430
431 /* XXX: Do not apply randomization to all-ftpr structs yet. */
432 return 0;
433
434 for (field = TYPE_FIELDS(node); field; field = TREE_CHAIN(field)) {
435 const_tree fieldtype = get_field_type(field);
436 enum tree_code code = TREE_CODE(fieldtype);
437
438 if (node == fieldtype)
439 continue;
440
441 if (!is_fptr(fieldtype))
442 return 0;
443
444 if (code != RECORD_TYPE && code != UNION_TYPE)
445 continue;
446
447 if (!is_pure_ops_struct(fieldtype))
448 return 0;
449 }
450
451 return 1;
452}
453
454static void randomize_type(tree type)
455{
456 tree variant;
457
458 gcc_assert(TREE_CODE(type) == RECORD_TYPE);
459
460 if (lookup_attribute("randomize_considered", TYPE_ATTRIBUTES(type)))
461 return;
462
463 if (lookup_attribute("randomize_layout", TYPE_ATTRIBUTES(TYPE_MAIN_VARIANT(type))) || is_pure_ops_struct(type))
464 relayout_struct(type);
465
466 for (variant = TYPE_MAIN_VARIANT(type); variant; variant = TYPE_NEXT_VARIANT(variant)) {
467 TYPE_ATTRIBUTES(type) = copy_list(TYPE_ATTRIBUTES(type));
468 TYPE_ATTRIBUTES(type) = tree_cons(get_identifier("randomize_considered"), NULL_TREE, TYPE_ATTRIBUTES(type));
469 }
470#ifdef __DEBUG_PLUGIN
471 fprintf(stderr, "Marking randomize_considered on struct %s\n", ORIG_TYPE_NAME(type));
472#ifdef __DEBUG_VERBOSE
473 debug_tree(type);
474#endif
475#endif
476}
477
478static void update_decl_size(tree decl)
479{
480 tree lastval, lastidx, field, init, type, flexsize;
481 unsigned HOST_WIDE_INT len;
482
483 type = TREE_TYPE(decl);
484
485 if (!lookup_attribute("has_flexarray", TYPE_ATTRIBUTES(type)))
486 return;
487
488 init = DECL_INITIAL(decl);
489 if (init == NULL_TREE || init == error_mark_node)
490 return;
491
492 if (TREE_CODE(init) != CONSTRUCTOR)
493 return;
494
495 len = CONSTRUCTOR_NELTS(init);
496 if (!len)
497 return;
498
499 lastval = CONSTRUCTOR_ELT(init, CONSTRUCTOR_NELTS(init) - 1)->value;
500 lastidx = CONSTRUCTOR_ELT(init, CONSTRUCTOR_NELTS(init) - 1)->index;
501
502 for (field = TYPE_FIELDS(TREE_TYPE(decl)); TREE_CHAIN(field); field = TREE_CHAIN(field))
503 ;
504
505 if (lastidx != field)
506 return;
507
508 if (TREE_CODE(lastval) != STRING_CST) {
509 error("Only string constants are supported as initializers "
510 "for randomized structures with flexible arrays");
511 return;
512 }
513
514 flexsize = bitsize_int(TREE_STRING_LENGTH(lastval) *
515 tree_to_uhwi(TYPE_SIZE(TREE_TYPE(TREE_TYPE(lastval)))));
516
517 DECL_SIZE(decl) = size_binop(PLUS_EXPR, TYPE_SIZE(type), flexsize);
518
519 return;
520}
521
522
523static void randomize_layout_finish_decl(void *event_data, void *data)
524{
525 tree decl = (tree)event_data;
526 tree type;
527
528 if (decl == NULL_TREE || decl == error_mark_node)
529 return;
530
531 type = TREE_TYPE(decl);
532
533 if (TREE_CODE(decl) != VAR_DECL)
534 return;
535
536 if (TREE_CODE(type) != RECORD_TYPE && TREE_CODE(type) != UNION_TYPE)
537 return;
538
539 if (!lookup_attribute("randomize_performed", TYPE_ATTRIBUTES(type)))
540 return;
541
542 DECL_SIZE(decl) = 0;
543 DECL_SIZE_UNIT(decl) = 0;
544 SET_DECL_ALIGN(decl, 0);
545 SET_DECL_MODE (decl, VOIDmode);
546 SET_DECL_RTL(decl, 0);
547 update_decl_size(decl);
548 layout_decl(decl, 0);
549}
550
551static void finish_type(void *event_data, void *data)
552{
553 tree type = (tree)event_data;
554
555 if (type == NULL_TREE || type == error_mark_node)
556 return;
557
558 if (TREE_CODE(type) != RECORD_TYPE)
559 return;
560
561 if (TYPE_FIELDS(type) == NULL_TREE)
562 return;
563
564 if (lookup_attribute("randomize_considered", TYPE_ATTRIBUTES(type)))
565 return;
566
567#ifdef __DEBUG_PLUGIN
568 fprintf(stderr, "Calling randomize_type on %s\n", ORIG_TYPE_NAME(type));
569#endif
570#ifdef __DEBUG_VERBOSE
571 debug_tree(type);
572#endif
573 randomize_type(type);
574
575 return;
576}
577
578static struct attribute_spec randomize_layout_attr = {
579 .name = "randomize_layout",
580 // related to args
581 .min_length = 0,
582 .max_length = 0,
583 .decl_required = false,
584 // need type declaration
585 .type_required = true,
586 .function_type_required = false,
587 .handler = handle_randomize_layout_attr,
588#if BUILDING_GCC_VERSION >= 4007
589 .affects_type_identity = true
590#endif
591};
592
593static struct attribute_spec no_randomize_layout_attr = {
594 .name = "no_randomize_layout",
595 // related to args
596 .min_length = 0,
597 .max_length = 0,
598 .decl_required = false,
599 // need type declaration
600 .type_required = true,
601 .function_type_required = false,
602 .handler = handle_randomize_layout_attr,
603#if BUILDING_GCC_VERSION >= 4007
604 .affects_type_identity = true
605#endif
606};
607
608static struct attribute_spec randomize_considered_attr = {
609 .name = "randomize_considered",
610 // related to args
611 .min_length = 0,
612 .max_length = 0,
613 .decl_required = false,
614 // need type declaration
615 .type_required = true,
616 .function_type_required = false,
617 .handler = handle_randomize_considered_attr,
618#if BUILDING_GCC_VERSION >= 4007
619 .affects_type_identity = false
620#endif
621};
622
623static struct attribute_spec randomize_performed_attr = {
624 .name = "randomize_performed",
625 // related to args
626 .min_length = 0,
627 .max_length = 0,
628 .decl_required = false,
629 // need type declaration
630 .type_required = true,
631 .function_type_required = false,
632 .handler = handle_randomize_performed_attr,
633#if BUILDING_GCC_VERSION >= 4007
634 .affects_type_identity = false
635#endif
636};
637
638static void register_attributes(void *event_data, void *data)
639{
640 register_attribute(&randomize_layout_attr);
641 register_attribute(&no_randomize_layout_attr);
642 register_attribute(&randomize_considered_attr);
643 register_attribute(&randomize_performed_attr);
644}
645
646static void check_bad_casts_in_constructor(tree var, tree init)
647{
648 unsigned HOST_WIDE_INT idx;
649 tree field, val;
650 tree field_type, val_type;
651
652 FOR_EACH_CONSTRUCTOR_ELT(CONSTRUCTOR_ELTS(init), idx, field, val) {
653 if (TREE_CODE(val) == CONSTRUCTOR) {
654 check_bad_casts_in_constructor(var, val);
655 continue;
656 }
657
658 /* pipacs' plugin creates franken-arrays that differ from those produced by
659 normal code which all have valid 'field' trees. work around this */
660 if (field == NULL_TREE)
661 continue;
662 field_type = TREE_TYPE(field);
663 val_type = TREE_TYPE(val);
664
665 if (TREE_CODE(field_type) != POINTER_TYPE || TREE_CODE(val_type) != POINTER_TYPE)
666 continue;
667
668 if (field_type == val_type)
669 continue;
670
671 field_type = TYPE_MAIN_VARIANT(strip_array_types(TYPE_MAIN_VARIANT(TREE_TYPE(field_type))));
672 val_type = TYPE_MAIN_VARIANT(strip_array_types(TYPE_MAIN_VARIANT(TREE_TYPE(val_type))));
673
674 if (field_type == void_type_node)
675 continue;
676 if (field_type == val_type)
677 continue;
678 if (TREE_CODE(val_type) != RECORD_TYPE)
679 continue;
680
681 if (!lookup_attribute("randomize_performed", TYPE_ATTRIBUTES(val_type)))
682 continue;
683 MISMATCH(DECL_SOURCE_LOCATION(var), "constructor\n", TYPE_MAIN_VARIANT(field_type), TYPE_MAIN_VARIANT(val_type));
684 }
685}
686
687/* derived from the constify plugin */
688static void check_global_variables(void *event_data, void *data)
689{
690 struct varpool_node *node;
691 tree init;
692
693 FOR_EACH_VARIABLE(node) {
694 tree var = NODE_DECL(node);
695 init = DECL_INITIAL(var);
696 if (init == NULL_TREE)
697 continue;
698
699 if (TREE_CODE(init) != CONSTRUCTOR)
700 continue;
701
702 check_bad_casts_in_constructor(var, init);
703 }
704}
705
706static bool dominated_by_is_err(const_tree rhs, basic_block bb)
707{
708 basic_block dom;
709 gimple dom_stmt;
710 gimple call_stmt;
711 const_tree dom_lhs;
712 const_tree poss_is_err_cond;
713 const_tree poss_is_err_func;
714 const_tree is_err_arg;
715
716 dom = get_immediate_dominator(CDI_DOMINATORS, bb);
717 if (!dom)
718 return false;
719
720 dom_stmt = last_stmt(dom);
721 if (!dom_stmt)
722 return false;
723
724 if (gimple_code(dom_stmt) != GIMPLE_COND)
725 return false;
726
727 if (gimple_cond_code(dom_stmt) != NE_EXPR)
728 return false;
729
730 if (!integer_zerop(gimple_cond_rhs(dom_stmt)))
731 return false;
732
733 poss_is_err_cond = gimple_cond_lhs(dom_stmt);
734
735 if (TREE_CODE(poss_is_err_cond) != SSA_NAME)
736 return false;
737
738 call_stmt = SSA_NAME_DEF_STMT(poss_is_err_cond);
739
740 if (gimple_code(call_stmt) != GIMPLE_CALL)
741 return false;
742
743 dom_lhs = gimple_get_lhs(call_stmt);
744 poss_is_err_func = gimple_call_fndecl(call_stmt);
745 if (!poss_is_err_func)
746 return false;
747 if (dom_lhs != poss_is_err_cond)
748 return false;
749 if (strcmp(DECL_NAME_POINTER(poss_is_err_func), "IS_ERR"))
750 return false;
751
752 is_err_arg = gimple_call_arg(call_stmt, 0);
753 if (!is_err_arg)
754 return false;
755
756 if (is_err_arg != rhs)
757 return false;
758
759 return true;
760}
761
762static void handle_local_var_initializers(void)
763{
764 tree var;
765 unsigned int i;
766
767 FOR_EACH_LOCAL_DECL(cfun, i, var) {
768 tree init = DECL_INITIAL(var);
769 if (!init)
770 continue;
771 if (TREE_CODE(init) != CONSTRUCTOR)
772 continue;
773 check_bad_casts_in_constructor(var, init);
774 }
775}
776
777static bool type_name_eq(gimple stmt, const_tree type_tree, const char *wanted_name)
778{
779 const char *type_name;
780
781 if (type_tree == NULL_TREE)
782 return false;
783
784 switch (TREE_CODE(type_tree)) {
785 case RECORD_TYPE:
786 type_name = TYPE_NAME_POINTER(type_tree);
787 break;
788 case INTEGER_TYPE:
789 if (TYPE_PRECISION(type_tree) == CHAR_TYPE_SIZE)
790 type_name = "char";
791 else {
792 INFORM(gimple_location(stmt), "found non-char INTEGER_TYPE cast comparison: %qT\n", type_tree);
793 debug_tree(type_tree);
794 return false;
795 }
796 break;
797 case POINTER_TYPE:
798 if (TREE_CODE(TREE_TYPE(type_tree)) == VOID_TYPE) {
799 type_name = "void *";
800 break;
801 } else {
802 INFORM(gimple_location(stmt), "found non-void POINTER_TYPE cast comparison %qT\n", type_tree);
803 debug_tree(type_tree);
804 return false;
805 }
806 default:
807 INFORM(gimple_location(stmt), "unhandled cast comparison: %qT\n", type_tree);
808 debug_tree(type_tree);
809 return false;
810 }
811
812 return strcmp(type_name, wanted_name) == 0;
813}
814
815static bool whitelisted_cast(gimple stmt, const_tree lhs_tree, const_tree rhs_tree)
816{
817 const struct whitelist_entry *entry;
818 expanded_location xloc = expand_location(gimple_location(stmt));
819
820 for (entry = whitelist; entry->pathname; entry++) {
821 if (!strstr(xloc.file, entry->pathname))
822 continue;
823
824 if (type_name_eq(stmt, lhs_tree, entry->lhs) && type_name_eq(stmt, rhs_tree, entry->rhs))
825 return true;
826 }
827
828 return false;
829}
830
831/*
832 * iterate over all statements to find "bad" casts:
833 * those where the address of the start of a structure is cast
834 * to a pointer of a structure of a different type, or a
835 * structure pointer type is cast to a different structure pointer type
836 */
837static unsigned int find_bad_casts_execute(void)
838{
839 basic_block bb;
840
841 handle_local_var_initializers();
842
843 FOR_EACH_BB_FN(bb, cfun) {
844 gimple_stmt_iterator gsi;
845
846 for (gsi = gsi_start_bb(bb); !gsi_end_p(gsi); gsi_next(&gsi)) {
847 gimple stmt;
848 const_tree lhs;
849 const_tree lhs_type;
850 const_tree rhs1;
851 const_tree rhs_type;
852 const_tree ptr_lhs_type;
853 const_tree ptr_rhs_type;
854 const_tree op0;
855 const_tree op0_type;
856 enum tree_code rhs_code;
857
858 stmt = gsi_stmt(gsi);
859
860#ifdef __DEBUG_PLUGIN
861#ifdef __DEBUG_VERBOSE
862 debug_gimple_stmt(stmt);
863 debug_tree(gimple_get_lhs(stmt));
864#endif
865#endif
866
867 if (gimple_code(stmt) != GIMPLE_ASSIGN)
868 continue;
869
870#ifdef __DEBUG_PLUGIN
871#ifdef __DEBUG_VERBOSE
872 debug_tree(gimple_assign_rhs1(stmt));
873#endif
874#endif
875
876
877 rhs_code = gimple_assign_rhs_code(stmt);
878
879 if (rhs_code != ADDR_EXPR && rhs_code != SSA_NAME)
880 continue;
881
882 lhs = gimple_get_lhs(stmt);
883 lhs_type = TREE_TYPE(lhs);
884 rhs1 = gimple_assign_rhs1(stmt);
885 rhs_type = TREE_TYPE(rhs1);
886
887 if (TREE_CODE(rhs_type) != POINTER_TYPE ||
888 TREE_CODE(lhs_type) != POINTER_TYPE)
889 continue;
890
891 ptr_lhs_type = TYPE_MAIN_VARIANT(strip_array_types(TYPE_MAIN_VARIANT(TREE_TYPE(lhs_type))));
892 ptr_rhs_type = TYPE_MAIN_VARIANT(strip_array_types(TYPE_MAIN_VARIANT(TREE_TYPE(rhs_type))));
893
894 if (ptr_rhs_type == void_type_node)
895 continue;
896
897 if (ptr_lhs_type == void_type_node)
898 continue;
899
900 if (dominated_by_is_err(rhs1, bb))
901 continue;
902
903 if (TREE_CODE(ptr_rhs_type) != RECORD_TYPE) {
904#ifndef __DEBUG_PLUGIN
905 if (lookup_attribute("randomize_performed", TYPE_ATTRIBUTES(ptr_lhs_type)))
906#endif
907 {
908 if (!whitelisted_cast(stmt, ptr_lhs_type, ptr_rhs_type))
909 MISMATCH(gimple_location(stmt), "rhs", ptr_lhs_type, ptr_rhs_type);
910 }
911 continue;
912 }
913
914 if (rhs_code == SSA_NAME && ptr_lhs_type == ptr_rhs_type)
915 continue;
916
917 if (rhs_code == ADDR_EXPR) {
918 op0 = TREE_OPERAND(rhs1, 0);
919
920 if (op0 == NULL_TREE)
921 continue;
922
923 if (TREE_CODE(op0) != VAR_DECL)
924 continue;
925
926 op0_type = TYPE_MAIN_VARIANT(strip_array_types(TYPE_MAIN_VARIANT(TREE_TYPE(op0))));
927 if (op0_type == ptr_lhs_type)
928 continue;
929
930#ifndef __DEBUG_PLUGIN
931 if (lookup_attribute("randomize_performed", TYPE_ATTRIBUTES(op0_type)))
932#endif
933 {
934 if (!whitelisted_cast(stmt, ptr_lhs_type, op0_type))
935 MISMATCH(gimple_location(stmt), "op0", ptr_lhs_type, op0_type);
936 }
937 } else {
938 const_tree ssa_name_var = SSA_NAME_VAR(rhs1);
939 /* skip bogus type casts introduced by container_of */
940 if (ssa_name_var != NULL_TREE && DECL_NAME(ssa_name_var) &&
941 !strcmp((const char *)DECL_NAME_POINTER(ssa_name_var), "__mptr"))
942 continue;
943#ifndef __DEBUG_PLUGIN
944 if (lookup_attribute("randomize_performed", TYPE_ATTRIBUTES(ptr_rhs_type)))
945#endif
946 {
947 if (!whitelisted_cast(stmt, ptr_lhs_type, ptr_rhs_type))
948 MISMATCH(gimple_location(stmt), "ssa", ptr_lhs_type, ptr_rhs_type);
949 }
950 }
951
952 }
953 }
954 return 0;
955}
956
957#define PASS_NAME find_bad_casts
958#define NO_GATE
959#define TODO_FLAGS_FINISH TODO_dump_func
960#include "gcc-generate-gimple-pass.h"
961
962__visible int plugin_init(struct plugin_name_args *plugin_info, struct plugin_gcc_version *version)
963{
964 int i;
965 const char * const plugin_name = plugin_info->base_name;
966 const int argc = plugin_info->argc;
967 const struct plugin_argument * const argv = plugin_info->argv;
968 bool enable = true;
969 int obtained_seed = 0;
970 struct register_pass_info find_bad_casts_pass_info;
971
972 find_bad_casts_pass_info.pass = make_find_bad_casts_pass();
973 find_bad_casts_pass_info.reference_pass_name = "ssa";
974 find_bad_casts_pass_info.ref_pass_instance_number = 1;
975 find_bad_casts_pass_info.pos_op = PASS_POS_INSERT_AFTER;
976
977 if (!plugin_default_version_check(version, &gcc_version)) {
978 error(G_("incompatible gcc/plugin versions"));
979 return 1;
980 }
981
982 if (strncmp(lang_hooks.name, "GNU C", 5) && !strncmp(lang_hooks.name, "GNU C+", 6)) {
983 inform(UNKNOWN_LOCATION, G_("%s supports C only, not %s"), plugin_name, lang_hooks.name);
984 enable = false;
985 }
986
987 for (i = 0; i < argc; ++i) {
988 if (!strcmp(argv[i].key, "disable")) {
989 enable = false;
990 continue;
991 }
992 if (!strcmp(argv[i].key, "performance-mode")) {
993 performance_mode = 1;
994 continue;
995 }
996 error(G_("unknown option '-fplugin-arg-%s-%s'"), plugin_name, argv[i].key);
997 }
998
999 if (strlen(randstruct_seed) != 64) {
1000 error(G_("invalid seed value supplied for %s plugin"), plugin_name);
1001 return 1;
1002 }
1003 obtained_seed = sscanf(randstruct_seed, "%016llx%016llx%016llx%016llx",
1004 &shuffle_seed[0], &shuffle_seed[1], &shuffle_seed[2], &shuffle_seed[3]);
1005 if (obtained_seed != 4) {
1006 error(G_("Invalid seed supplied for %s plugin"), plugin_name);
1007 return 1;
1008 }
1009
1010 register_callback(plugin_name, PLUGIN_INFO, NULL, &randomize_layout_plugin_info);
1011 if (enable) {
1012 register_callback(plugin_name, PLUGIN_ALL_IPA_PASSES_START, check_global_variables, NULL);
1013 register_callback(plugin_name, PLUGIN_PASS_MANAGER_SETUP, NULL, &find_bad_casts_pass_info);
1014 register_callback(plugin_name, PLUGIN_FINISH_TYPE, finish_type, NULL);
1015 register_callback(plugin_name, PLUGIN_FINISH_DECL, randomize_layout_finish_decl, NULL);
1016 }
1017 register_callback(plugin_name, PLUGIN_ATTRIBUTES, register_attributes, NULL);
1018
1019 return 0;
1020}
Linux 6.x block layer and io_uring tree(s)