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randstruct: Whitelist struct security_hook_heads cast
[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[] = {
fd466e06
KC		 49 /* walk struct security_hook_heads as an array of struct list_head */
50 { "security/security.c", "list_head", "security_hook_heads" },
313dd1b6
KC		 51 { }
52};
53
54/* from old Linux dcache.h */
55static inline unsigned long
56partial_name_hash(unsigned long c, unsigned long prevhash)
57{
58 return (prevhash + (c << 4) + (c >> 4)) * 11;
59}
60static inline unsigned int
61name_hash(const unsigned char *name)
62{
63 unsigned long hash = 0;
64 unsigned int len = strlen((const char *)name);
65 while (len--)
66 hash = partial_name_hash(*name++, hash);
67 return (unsigned int)hash;
68}
69
70static tree handle_randomize_layout_attr(tree *node, tree name, tree args, int flags, bool *no_add_attrs)
71{
72 tree type;
73
74 *no_add_attrs = true;
75 if (TREE_CODE(*node) == FUNCTION_DECL) {
76 error("%qE attribute does not apply to functions (%qF)", name, *node);
77 return NULL_TREE;
78 }
79
80 if (TREE_CODE(*node) == PARM_DECL) {
81 error("%qE attribute does not apply to function parameters (%qD)", name, *node);
82 return NULL_TREE;
83 }
84
85 if (TREE_CODE(*node) == VAR_DECL) {
86 error("%qE attribute does not apply to variables (%qD)", name, *node);
87 return NULL_TREE;
88 }
89
90 if (TYPE_P(*node)) {
91 type = *node;
92 } else {
93 gcc_assert(TREE_CODE(*node) == TYPE_DECL);
94 type = TREE_TYPE(*node);
95 }
96
97 if (TREE_CODE(type) != RECORD_TYPE) {
98 error("%qE attribute used on %qT applies to struct types only", name, type);
99 return NULL_TREE;
100 }
101
102 if (lookup_attribute(IDENTIFIER_POINTER(name), TYPE_ATTRIBUTES(type))) {
103 error("%qE attribute is already applied to the type %qT", name, type);
104 return NULL_TREE;
105 }
106
107 *no_add_attrs = false;
108
109 return NULL_TREE;
110}
111
112/* set on complete types that we don't need to inspect further at all */
113static tree handle_randomize_considered_attr(tree *node, tree name, tree args, int flags, bool *no_add_attrs)
114{
115 *no_add_attrs = false;
116 return NULL_TREE;
117}
118
119/*
120 * set on types that we've performed a shuffle on, to prevent re-shuffling
121 * this does not preclude us from inspecting its fields for potential shuffles
122 */
123static tree handle_randomize_performed_attr(tree *node, tree name, tree args, int flags, bool *no_add_attrs)
124{
125 *no_add_attrs = false;
126 return NULL_TREE;
127}
128
129/*
130 * 64bit variant of Bob Jenkins' public domain PRNG
131 * 256 bits of internal state
132 */
133
134typedef unsigned long long u64;
135
136typedef struct ranctx { u64 a; u64 b; u64 c; u64 d; } ranctx;
137
138#define rot(x,k) (((x)<<(k))|((x)>>(64-(k))))
139static u64 ranval(ranctx *x) {
140 u64 e = x->a - rot(x->b, 7);
141 x->a = x->b ^ rot(x->c, 13);
142 x->b = x->c + rot(x->d, 37);
143 x->c = x->d + e;
144 x->d = e + x->a;
145 return x->d;
146}
147
148static void raninit(ranctx *x, u64 *seed) {
149 int i;
150
151 x->a = seed[0];
152 x->b = seed[1];
153 x->c = seed[2];
154 x->d = seed[3];
155
156 for (i=0; i < 30; ++i)
157 (void)ranval(x);
158}
159
160static u64 shuffle_seed[4];
161
162struct partition_group {
163 tree tree_start;
164 unsigned long start;
165 unsigned long length;
166};
167
168static void partition_struct(tree *fields, unsigned long length, struct partition_group *size_groups, unsigned long *num_groups)
169{
170 unsigned long i;
171 unsigned long accum_size = 0;
172 unsigned long accum_length = 0;
173 unsigned long group_idx = 0;
174
175 gcc_assert(length < INT_MAX);
176
177 memset(size_groups, 0, sizeof(struct partition_group) * length);
178
179 for (i = 0; i < length; i++) {
180 if (size_groups[group_idx].tree_start == NULL_TREE) {
181 size_groups[group_idx].tree_start = fields[i];
182 size_groups[group_idx].start = i;
183 accum_length = 0;
184 accum_size = 0;
185 }
186 accum_size += (unsigned long)int_size_in_bytes(TREE_TYPE(fields[i]));
187 accum_length++;
188 if (accum_size >= 64) {
189 size_groups[group_idx].length = accum_length;
190 accum_length = 0;
191 group_idx++;
192 }
193 }
194
195 if (size_groups[group_idx].tree_start != NULL_TREE &&
196 !size_groups[group_idx].length) {
197 size_groups[group_idx].length = accum_length;
198 group_idx++;
199 }
200
201 *num_groups = group_idx;
202}
203
204static void performance_shuffle(tree *newtree, unsigned long length, ranctx *prng_state)
205{
206 unsigned long i, x;
207 struct partition_group size_group[length];
208 unsigned long num_groups = 0;
209 unsigned long randnum;
210
211 partition_struct(newtree, length, (struct partition_group *)&size_group, &num_groups);
212 for (i = num_groups - 1; i > 0; i--) {
213 struct partition_group tmp;
214 randnum = ranval(prng_state) % (i + 1);
215 tmp = size_group[i];
216 size_group[i] = size_group[randnum];
217 size_group[randnum] = tmp;
218 }
219
220 for (x = 0; x < num_groups; x++) {
221 for (i = size_group[x].start + size_group[x].length - 1; i > size_group[x].start; i--) {
222 tree tmp;
223 if (DECL_BIT_FIELD_TYPE(newtree[i]))
224 continue;
225 randnum = ranval(prng_state) % (i + 1);
226 // we could handle this case differently if desired
227 if (DECL_BIT_FIELD_TYPE(newtree[randnum]))
228 continue;
229 tmp = newtree[i];
230 newtree[i] = newtree[randnum];
231 newtree[randnum] = tmp;
232 }
233 }
234}
235
236static void full_shuffle(tree *newtree, unsigned long length, ranctx *prng_state)
237{
238 unsigned long i, randnum;
239
240 for (i = length - 1; i > 0; i--) {
241 tree tmp;
242 randnum = ranval(prng_state) % (i + 1);
243 tmp = newtree[i];
244 newtree[i] = newtree[randnum];
245 newtree[randnum] = tmp;
246 }
247}
248
249/* modern in-place Fisher-Yates shuffle */
250static void shuffle(const_tree type, tree *newtree, unsigned long length)
251{
252 unsigned long i;
253 u64 seed[4];
254 ranctx prng_state;
255 const unsigned char *structname;
256
257 if (length == 0)
258 return;
259
260 gcc_assert(TREE_CODE(type) == RECORD_TYPE);
261
262 structname = ORIG_TYPE_NAME(type);
263
264#ifdef __DEBUG_PLUGIN
265 fprintf(stderr, "Shuffling struct %s %p\n", (const char *)structname, type);
266#ifdef __DEBUG_VERBOSE
267 debug_tree((tree)type);
268#endif
269#endif
270
271 for (i = 0; i < 4; i++) {
272 seed[i] = shuffle_seed[i];
273 seed[i] ^= name_hash(structname);
274 }
275
276 raninit(&prng_state, (u64 *)&seed);
277
278 if (performance_mode)
279 performance_shuffle(newtree, length, &prng_state);
280 else
281 full_shuffle(newtree, length, &prng_state);
282}
283
284static bool is_flexible_array(const_tree field)
285{
286 const_tree fieldtype;
287 const_tree typesize;
288 const_tree elemtype;
289 const_tree elemsize;
290
291 fieldtype = TREE_TYPE(field);
292 typesize = TYPE_SIZE(fieldtype);
293
294 if (TREE_CODE(fieldtype) != ARRAY_TYPE)
295 return false;
296
297 elemtype = TREE_TYPE(fieldtype);
298 elemsize = TYPE_SIZE(elemtype);
299
300 /* size of type is represented in bits */
301
302 if (typesize == NULL_TREE && TYPE_DOMAIN(fieldtype) != NULL_TREE &&
303 TYPE_MAX_VALUE(TYPE_DOMAIN(fieldtype)) == NULL_TREE)
304 return true;
305
306 if (typesize != NULL_TREE &&
307 (TREE_CONSTANT(typesize) && (!tree_to_uhwi(typesize) ||
308 tree_to_uhwi(typesize) == tree_to_uhwi(elemsize))))
309 return true;
310
311 return false;
312}
313
314static int relayout_struct(tree type)
315{
316 unsigned long num_fields = (unsigned long)list_length(TYPE_FIELDS(type));
317 unsigned long shuffle_length = num_fields;
318 tree field;
319 tree newtree[num_fields];
320 unsigned long i;
321 tree list;
322 tree variant;
323 tree main_variant;
324 expanded_location xloc;
325 bool has_flexarray = false;
326
327 if (TYPE_FIELDS(type) == NULL_TREE)
328 return 0;
329
330 if (num_fields < 2)
331 return 0;
332
333 gcc_assert(TREE_CODE(type) == RECORD_TYPE);
334
335 gcc_assert(num_fields < INT_MAX);
336
337 if (lookup_attribute("randomize_performed", TYPE_ATTRIBUTES(type)) ||
338 lookup_attribute("no_randomize_layout", TYPE_ATTRIBUTES(TYPE_MAIN_VARIANT(type))))
339 return 0;
340
341 /* Workaround for 3rd-party VirtualBox source that we can't modify ourselves */
342 if (!strcmp((const char *)ORIG_TYPE_NAME(type), "INTNETTRUNKFACTORY") ||
343 !strcmp((const char *)ORIG_TYPE_NAME(type), "RAWPCIFACTORY"))
344 return 0;
345
346 /* throw out any structs in uapi */
347 xloc = expand_location(DECL_SOURCE_LOCATION(TYPE_FIELDS(type)));
348
349 if (strstr(xloc.file, "/uapi/"))
350 error(G_("attempted to randomize userland API struct %s"), ORIG_TYPE_NAME(type));
351
352 for (field = TYPE_FIELDS(type), i = 0; field; field = TREE_CHAIN(field), i++) {
353 gcc_assert(TREE_CODE(field) == FIELD_DECL);
354 newtree[i] = field;
355 }
356
357 /*
358 * enforce that we don't randomize the layout of the last
359 * element of a struct if it's a 0 or 1-length array
360 * or a proper flexible array
361 */
362 if (is_flexible_array(newtree[num_fields - 1])) {
363 has_flexarray = true;
364 shuffle_length--;
365 }
366
367 shuffle(type, (tree *)newtree, shuffle_length);
368
369 /*
370 * set up a bogus anonymous struct field designed to error out on unnamed struct initializers
371 * as gcc provides no other way to detect such code
372 */
373 list = make_node(FIELD_DECL);
374 TREE_CHAIN(list) = newtree[0];
375 TREE_TYPE(list) = void_type_node;
376 DECL_SIZE(list) = bitsize_zero_node;
377 DECL_NONADDRESSABLE_P(list) = 1;
378 DECL_FIELD_BIT_OFFSET(list) = bitsize_zero_node;
379 DECL_SIZE_UNIT(list) = size_zero_node;
380 DECL_FIELD_OFFSET(list) = size_zero_node;
381 DECL_CONTEXT(list) = type;
382 // to satisfy the constify plugin
383 TREE_READONLY(list) = 1;
384
385 for (i = 0; i < num_fields - 1; i++)
386 TREE_CHAIN(newtree[i]) = newtree[i+1];
387 TREE_CHAIN(newtree[num_fields - 1]) = NULL_TREE;
388
389 main_variant = TYPE_MAIN_VARIANT(type);
390 for (variant = main_variant; variant; variant = TYPE_NEXT_VARIANT(variant)) {
391 TYPE_FIELDS(variant) = list;
392 TYPE_ATTRIBUTES(variant) = copy_list(TYPE_ATTRIBUTES(variant));
393 TYPE_ATTRIBUTES(variant) = tree_cons(get_identifier("randomize_performed"), NULL_TREE, TYPE_ATTRIBUTES(variant));
394 TYPE_ATTRIBUTES(variant) = tree_cons(get_identifier("designated_init"), NULL_TREE, TYPE_ATTRIBUTES(variant));
395 if (has_flexarray)
396 TYPE_ATTRIBUTES(type) = tree_cons(get_identifier("has_flexarray"), NULL_TREE, TYPE_ATTRIBUTES(type));
397 }
398
399 /*
400 * force a re-layout of the main variant
401 * the TYPE_SIZE for all variants will be recomputed
402 * by finalize_type_size()
403 */
404 TYPE_SIZE(main_variant) = NULL_TREE;
405 layout_type(main_variant);
406 gcc_assert(TYPE_SIZE(main_variant) != NULL_TREE);
407
408 return 1;
409}
410
411/* from constify plugin */
412static const_tree get_field_type(const_tree field)
413{
414 return strip_array_types(TREE_TYPE(field));
415}
416
417/* from constify plugin */
418static bool is_fptr(const_tree fieldtype)
419{
420 if (TREE_CODE(fieldtype) != POINTER_TYPE)
421 return false;
422
423 return TREE_CODE(TREE_TYPE(fieldtype)) == FUNCTION_TYPE;
424}
425
426/* derived from constify plugin */
427static int is_pure_ops_struct(const_tree node)
428{
429 const_tree field;
430
431 gcc_assert(TREE_CODE(node) == RECORD_TYPE || TREE_CODE(node) == UNION_TYPE);
432
433 /* XXX: Do not apply randomization to all-ftpr structs yet. */
434 return 0;
435
436 for (field = TYPE_FIELDS(node); field; field = TREE_CHAIN(field)) {
437 const_tree fieldtype = get_field_type(field);
438 enum tree_code code = TREE_CODE(fieldtype);
439
440 if (node == fieldtype)
441 continue;
442
443 if (!is_fptr(fieldtype))
444 return 0;
445
446 if (code != RECORD_TYPE && code != UNION_TYPE)
447 continue;
448
449 if (!is_pure_ops_struct(fieldtype))
450 return 0;
451 }
452
453 return 1;
454}
455
456static void randomize_type(tree type)
457{
458 tree variant;
459
460 gcc_assert(TREE_CODE(type) == RECORD_TYPE);
461
462 if (lookup_attribute("randomize_considered", TYPE_ATTRIBUTES(type)))
463 return;
464
465 if (lookup_attribute("randomize_layout", TYPE_ATTRIBUTES(TYPE_MAIN_VARIANT(type))) || is_pure_ops_struct(type))
466 relayout_struct(type);
467
468 for (variant = TYPE_MAIN_VARIANT(type); variant; variant = TYPE_NEXT_VARIANT(variant)) {
469 TYPE_ATTRIBUTES(type) = copy_list(TYPE_ATTRIBUTES(type));
470 TYPE_ATTRIBUTES(type) = tree_cons(get_identifier("randomize_considered"), NULL_TREE, TYPE_ATTRIBUTES(type));
471 }
472#ifdef __DEBUG_PLUGIN
473 fprintf(stderr, "Marking randomize_considered on struct %s\n", ORIG_TYPE_NAME(type));
474#ifdef __DEBUG_VERBOSE
475 debug_tree(type);
476#endif
477#endif
478}
479
480static void update_decl_size(tree decl)
481{
482 tree lastval, lastidx, field, init, type, flexsize;
483 unsigned HOST_WIDE_INT len;
484
485 type = TREE_TYPE(decl);
486
487 if (!lookup_attribute("has_flexarray", TYPE_ATTRIBUTES(type)))
488 return;
489
490 init = DECL_INITIAL(decl);
491 if (init == NULL_TREE || init == error_mark_node)
492 return;
493
494 if (TREE_CODE(init) != CONSTRUCTOR)
495 return;
496
497 len = CONSTRUCTOR_NELTS(init);
498 if (!len)
499 return;
500
501 lastval = CONSTRUCTOR_ELT(init, CONSTRUCTOR_NELTS(init) - 1)->value;
502 lastidx = CONSTRUCTOR_ELT(init, CONSTRUCTOR_NELTS(init) - 1)->index;
503
504 for (field = TYPE_FIELDS(TREE_TYPE(decl)); TREE_CHAIN(field); field = TREE_CHAIN(field))
505 ;
506
507 if (lastidx != field)
508 return;
509
510 if (TREE_CODE(lastval) != STRING_CST) {
511 error("Only string constants are supported as initializers "
512 "for randomized structures with flexible arrays");
513 return;
514 }
515
516 flexsize = bitsize_int(TREE_STRING_LENGTH(lastval) *
517 tree_to_uhwi(TYPE_SIZE(TREE_TYPE(TREE_TYPE(lastval)))));
518
519 DECL_SIZE(decl) = size_binop(PLUS_EXPR, TYPE_SIZE(type), flexsize);
520
521 return;
522}
523
524
525static void randomize_layout_finish_decl(void *event_data, void *data)
526{
527 tree decl = (tree)event_data;
528 tree type;
529
530 if (decl == NULL_TREE || decl == error_mark_node)
531 return;
532
533 type = TREE_TYPE(decl);
534
535 if (TREE_CODE(decl) != VAR_DECL)
536 return;
537
538 if (TREE_CODE(type) != RECORD_TYPE && TREE_CODE(type) != UNION_TYPE)
539 return;
540
541 if (!lookup_attribute("randomize_performed", TYPE_ATTRIBUTES(type)))
542 return;
543
544 DECL_SIZE(decl) = 0;
545 DECL_SIZE_UNIT(decl) = 0;
546 SET_DECL_ALIGN(decl, 0);
547 SET_DECL_MODE (decl, VOIDmode);
548 SET_DECL_RTL(decl, 0);
549 update_decl_size(decl);
550 layout_decl(decl, 0);
551}
552
553static void finish_type(void *event_data, void *data)
554{
555 tree type = (tree)event_data;
556
557 if (type == NULL_TREE || type == error_mark_node)
558 return;
559
560 if (TREE_CODE(type) != RECORD_TYPE)
561 return;
562
563 if (TYPE_FIELDS(type) == NULL_TREE)
564 return;
565
566 if (lookup_attribute("randomize_considered", TYPE_ATTRIBUTES(type)))
567 return;
568
569#ifdef __DEBUG_PLUGIN
570 fprintf(stderr, "Calling randomize_type on %s\n", ORIG_TYPE_NAME(type));
571#endif
572#ifdef __DEBUG_VERBOSE
573 debug_tree(type);
574#endif
575 randomize_type(type);
576
577 return;
578}
579
580static struct attribute_spec randomize_layout_attr = {
581 .name = "randomize_layout",
582 // related to args
583 .min_length = 0,
584 .max_length = 0,
585 .decl_required = false,
586 // need type declaration
587 .type_required = true,
588 .function_type_required = false,
589 .handler = handle_randomize_layout_attr,
590#if BUILDING_GCC_VERSION >= 4007
591 .affects_type_identity = true
592#endif
593};
594
595static struct attribute_spec no_randomize_layout_attr = {
596 .name = "no_randomize_layout",
597 // related to args
598 .min_length = 0,
599 .max_length = 0,
600 .decl_required = false,
601 // need type declaration
602 .type_required = true,
603 .function_type_required = false,
604 .handler = handle_randomize_layout_attr,
605#if BUILDING_GCC_VERSION >= 4007
606 .affects_type_identity = true
607#endif
608};
609
610static struct attribute_spec randomize_considered_attr = {
611 .name = "randomize_considered",
612 // related to args
613 .min_length = 0,
614 .max_length = 0,
615 .decl_required = false,
616 // need type declaration
617 .type_required = true,
618 .function_type_required = false,
619 .handler = handle_randomize_considered_attr,
620#if BUILDING_GCC_VERSION >= 4007
621 .affects_type_identity = false
622#endif
623};
624
625static struct attribute_spec randomize_performed_attr = {
626 .name = "randomize_performed",
627 // related to args
628 .min_length = 0,
629 .max_length = 0,
630 .decl_required = false,
631 // need type declaration
632 .type_required = true,
633 .function_type_required = false,
634 .handler = handle_randomize_performed_attr,
635#if BUILDING_GCC_VERSION >= 4007
636 .affects_type_identity = false
637#endif
638};
639
640static void register_attributes(void *event_data, void *data)
641{
642 register_attribute(&randomize_layout_attr);
643 register_attribute(&no_randomize_layout_attr);
644 register_attribute(&randomize_considered_attr);
645 register_attribute(&randomize_performed_attr);
646}
647
648static void check_bad_casts_in_constructor(tree var, tree init)
649{
650 unsigned HOST_WIDE_INT idx;
651 tree field, val;
652 tree field_type, val_type;
653
654 FOR_EACH_CONSTRUCTOR_ELT(CONSTRUCTOR_ELTS(init), idx, field, val) {
655 if (TREE_CODE(val) == CONSTRUCTOR) {
656 check_bad_casts_in_constructor(var, val);
657 continue;
658 }
659
660 /* pipacs' plugin creates franken-arrays that differ from those produced by
661 normal code which all have valid 'field' trees. work around this */
662 if (field == NULL_TREE)
663 continue;
664 field_type = TREE_TYPE(field);
665 val_type = TREE_TYPE(val);
666
667 if (TREE_CODE(field_type) != POINTER_TYPE || TREE_CODE(val_type) != POINTER_TYPE)
668 continue;
669
670 if (field_type == val_type)
671 continue;
672
673 field_type = TYPE_MAIN_VARIANT(strip_array_types(TYPE_MAIN_VARIANT(TREE_TYPE(field_type))));
674 val_type = TYPE_MAIN_VARIANT(strip_array_types(TYPE_MAIN_VARIANT(TREE_TYPE(val_type))));
675
676 if (field_type == void_type_node)
677 continue;
678 if (field_type == val_type)
679 continue;
680 if (TREE_CODE(val_type) != RECORD_TYPE)
681 continue;
682
683 if (!lookup_attribute("randomize_performed", TYPE_ATTRIBUTES(val_type)))
684 continue;
685 MISMATCH(DECL_SOURCE_LOCATION(var), "constructor\n", TYPE_MAIN_VARIANT(field_type), TYPE_MAIN_VARIANT(val_type));
686 }
687}
688
689/* derived from the constify plugin */
690static void check_global_variables(void *event_data, void *data)
691{
692 struct varpool_node *node;
693 tree init;
694
695 FOR_EACH_VARIABLE(node) {
696 tree var = NODE_DECL(node);
697 init = DECL_INITIAL(var);
698 if (init == NULL_TREE)
699 continue;
700
701 if (TREE_CODE(init) != CONSTRUCTOR)
702 continue;
703
704 check_bad_casts_in_constructor(var, init);
705 }
706}
707
708static bool dominated_by_is_err(const_tree rhs, basic_block bb)
709{
710 basic_block dom;
711 gimple dom_stmt;
712 gimple call_stmt;
713 const_tree dom_lhs;
714 const_tree poss_is_err_cond;
715 const_tree poss_is_err_func;
716 const_tree is_err_arg;
717
718 dom = get_immediate_dominator(CDI_DOMINATORS, bb);
719 if (!dom)
720 return false;
721
722 dom_stmt = last_stmt(dom);
723 if (!dom_stmt)
724 return false;
725
726 if (gimple_code(dom_stmt) != GIMPLE_COND)
727 return false;
728
729 if (gimple_cond_code(dom_stmt) != NE_EXPR)
730 return false;
731
732 if (!integer_zerop(gimple_cond_rhs(dom_stmt)))
733 return false;
734
735 poss_is_err_cond = gimple_cond_lhs(dom_stmt);
736
737 if (TREE_CODE(poss_is_err_cond) != SSA_NAME)
738 return false;
739
740 call_stmt = SSA_NAME_DEF_STMT(poss_is_err_cond);
741
742 if (gimple_code(call_stmt) != GIMPLE_CALL)
743 return false;
744
745 dom_lhs = gimple_get_lhs(call_stmt);
746 poss_is_err_func = gimple_call_fndecl(call_stmt);
747 if (!poss_is_err_func)
748 return false;
749 if (dom_lhs != poss_is_err_cond)
750 return false;
751 if (strcmp(DECL_NAME_POINTER(poss_is_err_func), "IS_ERR"))
752 return false;
753
754 is_err_arg = gimple_call_arg(call_stmt, 0);
755 if (!is_err_arg)
756 return false;
757
758 if (is_err_arg != rhs)
759 return false;
760
761 return true;
762}
763
764static void handle_local_var_initializers(void)
765{
766 tree var;
767 unsigned int i;
768
769 FOR_EACH_LOCAL_DECL(cfun, i, var) {
770 tree init = DECL_INITIAL(var);
771 if (!init)
772 continue;
773 if (TREE_CODE(init) != CONSTRUCTOR)
774 continue;
775 check_bad_casts_in_constructor(var, init);
776 }
777}
778
779static bool type_name_eq(gimple stmt, const_tree type_tree, const char *wanted_name)
780{
781 const char *type_name;
782
783 if (type_tree == NULL_TREE)
784 return false;
785
786 switch (TREE_CODE(type_tree)) {
787 case RECORD_TYPE:
788 type_name = TYPE_NAME_POINTER(type_tree);
789 break;
790 case INTEGER_TYPE:
791 if (TYPE_PRECISION(type_tree) == CHAR_TYPE_SIZE)
792 type_name = "char";
793 else {
794 INFORM(gimple_location(stmt), "found non-char INTEGER_TYPE cast comparison: %qT\n", type_tree);
795 debug_tree(type_tree);
796 return false;
797 }
798 break;
799 case POINTER_TYPE:
800 if (TREE_CODE(TREE_TYPE(type_tree)) == VOID_TYPE) {
801 type_name = "void *";
802 break;
803 } else {
804 INFORM(gimple_location(stmt), "found non-void POINTER_TYPE cast comparison %qT\n", type_tree);
805 debug_tree(type_tree);
806 return false;
807 }
808 default:
809 INFORM(gimple_location(stmt), "unhandled cast comparison: %qT\n", type_tree);
810 debug_tree(type_tree);
811 return false;
812 }
813
814 return strcmp(type_name, wanted_name) == 0;
815}
816
817static bool whitelisted_cast(gimple stmt, const_tree lhs_tree, const_tree rhs_tree)
818{
819 const struct whitelist_entry *entry;
820 expanded_location xloc = expand_location(gimple_location(stmt));
821
822 for (entry = whitelist; entry->pathname; entry++) {
823 if (!strstr(xloc.file, entry->pathname))
824 continue;
825
826 if (type_name_eq(stmt, lhs_tree, entry->lhs) && type_name_eq(stmt, rhs_tree, entry->rhs))
827 return true;
828 }
829
830 return false;
831}
832
833/*
834 * iterate over all statements to find "bad" casts:
835 * those where the address of the start of a structure is cast
836 * to a pointer of a structure of a different type, or a
837 * structure pointer type is cast to a different structure pointer type
838 */
839static unsigned int find_bad_casts_execute(void)
840{
841 basic_block bb;
842
843 handle_local_var_initializers();
844
845 FOR_EACH_BB_FN(bb, cfun) {
846 gimple_stmt_iterator gsi;
847
848 for (gsi = gsi_start_bb(bb); !gsi_end_p(gsi); gsi_next(&gsi)) {
849 gimple stmt;
850 const_tree lhs;
851 const_tree lhs_type;
852 const_tree rhs1;
853 const_tree rhs_type;
854 const_tree ptr_lhs_type;
855 const_tree ptr_rhs_type;
856 const_tree op0;
857 const_tree op0_type;
858 enum tree_code rhs_code;
859
860 stmt = gsi_stmt(gsi);
861
862#ifdef __DEBUG_PLUGIN
863#ifdef __DEBUG_VERBOSE
864 debug_gimple_stmt(stmt);
865 debug_tree(gimple_get_lhs(stmt));
866#endif
867#endif
868
869 if (gimple_code(stmt) != GIMPLE_ASSIGN)
870 continue;
871
872#ifdef __DEBUG_PLUGIN
873#ifdef __DEBUG_VERBOSE
874 debug_tree(gimple_assign_rhs1(stmt));
875#endif
876#endif
877
878
879 rhs_code = gimple_assign_rhs_code(stmt);
880
881 if (rhs_code != ADDR_EXPR && rhs_code != SSA_NAME)
882 continue;
883
884 lhs = gimple_get_lhs(stmt);
885 lhs_type = TREE_TYPE(lhs);
886 rhs1 = gimple_assign_rhs1(stmt);
887 rhs_type = TREE_TYPE(rhs1);
888
889 if (TREE_CODE(rhs_type) != POINTER_TYPE ||
890 TREE_CODE(lhs_type) != POINTER_TYPE)
891 continue;
892
893 ptr_lhs_type = TYPE_MAIN_VARIANT(strip_array_types(TYPE_MAIN_VARIANT(TREE_TYPE(lhs_type))));
894 ptr_rhs_type = TYPE_MAIN_VARIANT(strip_array_types(TYPE_MAIN_VARIANT(TREE_TYPE(rhs_type))));
895
896 if (ptr_rhs_type == void_type_node)
897 continue;
898
899 if (ptr_lhs_type == void_type_node)
900 continue;
901
902 if (dominated_by_is_err(rhs1, bb))
903 continue;
904
905 if (TREE_CODE(ptr_rhs_type) != RECORD_TYPE) {
906#ifndef __DEBUG_PLUGIN
907 if (lookup_attribute("randomize_performed", TYPE_ATTRIBUTES(ptr_lhs_type)))
908#endif
909 {
910 if (!whitelisted_cast(stmt, ptr_lhs_type, ptr_rhs_type))
911 MISMATCH(gimple_location(stmt), "rhs", ptr_lhs_type, ptr_rhs_type);
912 }
913 continue;
914 }
915
916 if (rhs_code == SSA_NAME && ptr_lhs_type == ptr_rhs_type)
917 continue;
918
919 if (rhs_code == ADDR_EXPR) {
920 op0 = TREE_OPERAND(rhs1, 0);
921
922 if (op0 == NULL_TREE)
923 continue;
924
925 if (TREE_CODE(op0) != VAR_DECL)
926 continue;
927
928 op0_type = TYPE_MAIN_VARIANT(strip_array_types(TYPE_MAIN_VARIANT(TREE_TYPE(op0))));
929 if (op0_type == ptr_lhs_type)
930 continue;
931
932#ifndef __DEBUG_PLUGIN
933 if (lookup_attribute("randomize_performed", TYPE_ATTRIBUTES(op0_type)))
934#endif
935 {
936 if (!whitelisted_cast(stmt, ptr_lhs_type, op0_type))
937 MISMATCH(gimple_location(stmt), "op0", ptr_lhs_type, op0_type);
938 }
939 } else {
940 const_tree ssa_name_var = SSA_NAME_VAR(rhs1);
941 /* skip bogus type casts introduced by container_of */
942 if (ssa_name_var != NULL_TREE && DECL_NAME(ssa_name_var) &&
943 !strcmp((const char *)DECL_NAME_POINTER(ssa_name_var), "__mptr"))
944 continue;
945#ifndef __DEBUG_PLUGIN
946 if (lookup_attribute("randomize_performed", TYPE_ATTRIBUTES(ptr_rhs_type)))
947#endif
948 {
949 if (!whitelisted_cast(stmt, ptr_lhs_type, ptr_rhs_type))
950 MISMATCH(gimple_location(stmt), "ssa", ptr_lhs_type, ptr_rhs_type);
951 }
952 }
953
954 }
955 }
956 return 0;
957}
958
959#define PASS_NAME find_bad_casts
960#define NO_GATE
961#define TODO_FLAGS_FINISH TODO_dump_func
962#include "gcc-generate-gimple-pass.h"
963
964__visible int plugin_init(struct plugin_name_args *plugin_info, struct plugin_gcc_version *version)
965{
966 int i;
967 const char * const plugin_name = plugin_info->base_name;
968 const int argc = plugin_info->argc;
969 const struct plugin_argument * const argv = plugin_info->argv;
970 bool enable = true;
971 int obtained_seed = 0;
972 struct register_pass_info find_bad_casts_pass_info;
973
974 find_bad_casts_pass_info.pass = make_find_bad_casts_pass();
975 find_bad_casts_pass_info.reference_pass_name = "ssa";
976 find_bad_casts_pass_info.ref_pass_instance_number = 1;
977 find_bad_casts_pass_info.pos_op = PASS_POS_INSERT_AFTER;
978
979 if (!plugin_default_version_check(version, &gcc_version)) {
980 error(G_("incompatible gcc/plugin versions"));
981 return 1;
982 }
983
984 if (strncmp(lang_hooks.name, "GNU C", 5) && !strncmp(lang_hooks.name, "GNU C+", 6)) {
985 inform(UNKNOWN_LOCATION, G_("%s supports C only, not %s"), plugin_name, lang_hooks.name);
986 enable = false;
987 }
988
989 for (i = 0; i < argc; ++i) {
990 if (!strcmp(argv[i].key, "disable")) {
991 enable = false;
992 continue;
993 }
994 if (!strcmp(argv[i].key, "performance-mode")) {
995 performance_mode = 1;
996 continue;
997 }
998 error(G_("unknown option '-fplugin-arg-%s-%s'"), plugin_name, argv[i].key);
999 }
1000
1001 if (strlen(randstruct_seed) != 64) {
1002 error(G_("invalid seed value supplied for %s plugin"), plugin_name);
1003 return 1;
1004 }
1005 obtained_seed = sscanf(randstruct_seed, "%016llx%016llx%016llx%016llx",
1006 &shuffle_seed[0], &shuffle_seed[1], &shuffle_seed[2], &shuffle_seed[3]);
1007 if (obtained_seed != 4) {
1008 error(G_("Invalid seed supplied for %s plugin"), plugin_name);
1009 return 1;
1010 }
1011
1012 register_callback(plugin_name, PLUGIN_INFO, NULL, &randomize_layout_plugin_info);
1013 if (enable) {
1014 register_callback(plugin_name, PLUGIN_ALL_IPA_PASSES_START, check_global_variables, NULL);
1015 register_callback(plugin_name, PLUGIN_PASS_MANAGER_SETUP, NULL, &find_bad_casts_pass_info);
1016 register_callback(plugin_name, PLUGIN_FINISH_TYPE, finish_type, NULL);
1017 register_callback(plugin_name, PLUGIN_FINISH_DECL, randomize_layout_finish_decl, NULL);
1018 }
1019 register_callback(plugin_name, PLUGIN_ATTRIBUTES, register_attributes, NULL);
1020
1021 return 0;
1022}
Linux 6.x block layer and io_uring tree(s)