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security: don't treat structure as an array of struct hlist_head
[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[] = {
1854c19c
KC		 49 /* NIU overloads mapping with page struct */
50 { "drivers/net/ethernet/sun/niu.c", "page", "address_space" },
b07b6584
KC		 51 /* unix_skb_parms via UNIXCB() buffer */
52 { "net/unix/af_unix.c", "unix_skb_parms", "char" },
802762cd
KC		 53 /* big_key payload.data struct splashing */
54 { "security/keys/big_key.c", "path", "void *" },
313dd1b6
KC		 55 { }
56};
57
58/* from old Linux dcache.h */
59static inline unsigned long
60partial_name_hash(unsigned long c, unsigned long prevhash)
61{
62 return (prevhash + (c << 4) + (c >> 4)) * 11;
63}
64static inline unsigned int
65name_hash(const unsigned char *name)
66{
67 unsigned long hash = 0;
68 unsigned int len = strlen((const char *)name);
69 while (len--)
70 hash = partial_name_hash(*name++, hash);
71 return (unsigned int)hash;
72}
73
74static tree handle_randomize_layout_attr(tree *node, tree name, tree args, int flags, bool *no_add_attrs)
75{
76 tree type;
77
78 *no_add_attrs = true;
79 if (TREE_CODE(*node) == FUNCTION_DECL) {
80 error("%qE attribute does not apply to functions (%qF)", name, *node);
81 return NULL_TREE;
82 }
83
84 if (TREE_CODE(*node) == PARM_DECL) {
85 error("%qE attribute does not apply to function parameters (%qD)", name, *node);
86 return NULL_TREE;
87 }
88
89 if (TREE_CODE(*node) == VAR_DECL) {
90 error("%qE attribute does not apply to variables (%qD)", name, *node);
91 return NULL_TREE;
92 }
93
94 if (TYPE_P(*node)) {
95 type = *node;
96 } else {
97 gcc_assert(TREE_CODE(*node) == TYPE_DECL);
98 type = TREE_TYPE(*node);
99 }
100
101 if (TREE_CODE(type) != RECORD_TYPE) {
102 error("%qE attribute used on %qT applies to struct types only", name, type);
103 return NULL_TREE;
104 }
105
106 if (lookup_attribute(IDENTIFIER_POINTER(name), TYPE_ATTRIBUTES(type))) {
107 error("%qE attribute is already applied to the type %qT", name, type);
108 return NULL_TREE;
109 }
110
111 *no_add_attrs = false;
112
113 return NULL_TREE;
114}
115
116/* set on complete types that we don't need to inspect further at all */
117static tree handle_randomize_considered_attr(tree *node, tree name, tree args, int flags, bool *no_add_attrs)
118{
119 *no_add_attrs = false;
120 return NULL_TREE;
121}
122
123/*
124 * set on types that we've performed a shuffle on, to prevent re-shuffling
125 * this does not preclude us from inspecting its fields for potential shuffles
126 */
127static tree handle_randomize_performed_attr(tree *node, tree name, tree args, int flags, bool *no_add_attrs)
128{
129 *no_add_attrs = false;
130 return NULL_TREE;
131}
132
133/*
134 * 64bit variant of Bob Jenkins' public domain PRNG
135 * 256 bits of internal state
136 */
137
138typedef unsigned long long u64;
139
140typedef struct ranctx { u64 a; u64 b; u64 c; u64 d; } ranctx;
141
142#define rot(x,k) (((x)<<(k))|((x)>>(64-(k))))
143static u64 ranval(ranctx *x) {
144 u64 e = x->a - rot(x->b, 7);
145 x->a = x->b ^ rot(x->c, 13);
146 x->b = x->c + rot(x->d, 37);
147 x->c = x->d + e;
148 x->d = e + x->a;
149 return x->d;
150}
151
152static void raninit(ranctx *x, u64 *seed) {
153 int i;
154
155 x->a = seed[0];
156 x->b = seed[1];
157 x->c = seed[2];
158 x->d = seed[3];
159
160 for (i=0; i < 30; ++i)
161 (void)ranval(x);
162}
163
164static u64 shuffle_seed[4];
165
166struct partition_group {
167 tree tree_start;
168 unsigned long start;
169 unsigned long length;
170};
171
172static void partition_struct(tree *fields, unsigned long length, struct partition_group *size_groups, unsigned long *num_groups)
173{
174 unsigned long i;
175 unsigned long accum_size = 0;
176 unsigned long accum_length = 0;
177 unsigned long group_idx = 0;
178
179 gcc_assert(length < INT_MAX);
180
181 memset(size_groups, 0, sizeof(struct partition_group) * length);
182
183 for (i = 0; i < length; i++) {
184 if (size_groups[group_idx].tree_start == NULL_TREE) {
185 size_groups[group_idx].tree_start = fields[i];
186 size_groups[group_idx].start = i;
187 accum_length = 0;
188 accum_size = 0;
189 }
190 accum_size += (unsigned long)int_size_in_bytes(TREE_TYPE(fields[i]));
191 accum_length++;
192 if (accum_size >= 64) {
193 size_groups[group_idx].length = accum_length;
194 accum_length = 0;
195 group_idx++;
196 }
197 }
198
199 if (size_groups[group_idx].tree_start != NULL_TREE &&
200 !size_groups[group_idx].length) {
201 size_groups[group_idx].length = accum_length;
202 group_idx++;
203 }
204
205 *num_groups = group_idx;
206}
207
208static void performance_shuffle(tree *newtree, unsigned long length, ranctx *prng_state)
209{
210 unsigned long i, x;
211 struct partition_group size_group[length];
212 unsigned long num_groups = 0;
213 unsigned long randnum;
214
215 partition_struct(newtree, length, (struct partition_group *)&size_group, &num_groups);
216 for (i = num_groups - 1; i > 0; i--) {
217 struct partition_group tmp;
218 randnum = ranval(prng_state) % (i + 1);
219 tmp = size_group[i];
220 size_group[i] = size_group[randnum];
221 size_group[randnum] = tmp;
222 }
223
224 for (x = 0; x < num_groups; x++) {
225 for (i = size_group[x].start + size_group[x].length - 1; i > size_group[x].start; i--) {
226 tree tmp;
227 if (DECL_BIT_FIELD_TYPE(newtree[i]))
228 continue;
229 randnum = ranval(prng_state) % (i + 1);
230 // we could handle this case differently if desired
231 if (DECL_BIT_FIELD_TYPE(newtree[randnum]))
232 continue;
233 tmp = newtree[i];
234 newtree[i] = newtree[randnum];
235 newtree[randnum] = tmp;
236 }
237 }
238}
239
240static void full_shuffle(tree *newtree, unsigned long length, ranctx *prng_state)
241{
242 unsigned long i, randnum;
243
244 for (i = length - 1; i > 0; i--) {
245 tree tmp;
246 randnum = ranval(prng_state) % (i + 1);
247 tmp = newtree[i];
248 newtree[i] = newtree[randnum];
249 newtree[randnum] = tmp;
250 }
251}
252
253/* modern in-place Fisher-Yates shuffle */
254static void shuffle(const_tree type, tree *newtree, unsigned long length)
255{
256 unsigned long i;
257 u64 seed[4];
258 ranctx prng_state;
259 const unsigned char *structname;
260
261 if (length == 0)
262 return;
263
264 gcc_assert(TREE_CODE(type) == RECORD_TYPE);
265
266 structname = ORIG_TYPE_NAME(type);
267
268#ifdef __DEBUG_PLUGIN
269 fprintf(stderr, "Shuffling struct %s %p\n", (const char *)structname, type);
270#ifdef __DEBUG_VERBOSE
271 debug_tree((tree)type);
272#endif
273#endif
274
275 for (i = 0; i < 4; i++) {
276 seed[i] = shuffle_seed[i];
277 seed[i] ^= name_hash(structname);
278 }
279
280 raninit(&prng_state, (u64 *)&seed);
281
282 if (performance_mode)
283 performance_shuffle(newtree, length, &prng_state);
284 else
285 full_shuffle(newtree, length, &prng_state);
286}
287
288static bool is_flexible_array(const_tree field)
289{
290 const_tree fieldtype;
291 const_tree typesize;
292 const_tree elemtype;
293 const_tree elemsize;
294
295 fieldtype = TREE_TYPE(field);
296 typesize = TYPE_SIZE(fieldtype);
297
298 if (TREE_CODE(fieldtype) != ARRAY_TYPE)
299 return false;
300
301 elemtype = TREE_TYPE(fieldtype);
302 elemsize = TYPE_SIZE(elemtype);
303
304 /* size of type is represented in bits */
305
306 if (typesize == NULL_TREE && TYPE_DOMAIN(fieldtype) != NULL_TREE &&
307 TYPE_MAX_VALUE(TYPE_DOMAIN(fieldtype)) == NULL_TREE)
308 return true;
309
310 if (typesize != NULL_TREE &&
311 (TREE_CONSTANT(typesize) && (!tree_to_uhwi(typesize) ||
312 tree_to_uhwi(typesize) == tree_to_uhwi(elemsize))))
313 return true;
314
315 return false;
316}
317
318static int relayout_struct(tree type)
319{
320 unsigned long num_fields = (unsigned long)list_length(TYPE_FIELDS(type));
321 unsigned long shuffle_length = num_fields;
322 tree field;
323 tree newtree[num_fields];
324 unsigned long i;
325 tree list;
326 tree variant;
327 tree main_variant;
328 expanded_location xloc;
329 bool has_flexarray = false;
330
331 if (TYPE_FIELDS(type) == NULL_TREE)
332 return 0;
333
334 if (num_fields < 2)
335 return 0;
336
337 gcc_assert(TREE_CODE(type) == RECORD_TYPE);
338
339 gcc_assert(num_fields < INT_MAX);
340
341 if (lookup_attribute("randomize_performed", TYPE_ATTRIBUTES(type)) ||
342 lookup_attribute("no_randomize_layout", TYPE_ATTRIBUTES(TYPE_MAIN_VARIANT(type))))
343 return 0;
344
345 /* Workaround for 3rd-party VirtualBox source that we can't modify ourselves */
346 if (!strcmp((const char *)ORIG_TYPE_NAME(type), "INTNETTRUNKFACTORY") ||
347 !strcmp((const char *)ORIG_TYPE_NAME(type), "RAWPCIFACTORY"))
348 return 0;
349
350 /* throw out any structs in uapi */
351 xloc = expand_location(DECL_SOURCE_LOCATION(TYPE_FIELDS(type)));
352
353 if (strstr(xloc.file, "/uapi/"))
354 error(G_("attempted to randomize userland API struct %s"), ORIG_TYPE_NAME(type));
355
356 for (field = TYPE_FIELDS(type), i = 0; field; field = TREE_CHAIN(field), i++) {
357 gcc_assert(TREE_CODE(field) == FIELD_DECL);
358 newtree[i] = field;
359 }
360
361 /*
362 * enforce that we don't randomize the layout of the last
363 * element of a struct if it's a 0 or 1-length array
364 * or a proper flexible array
365 */
366 if (is_flexible_array(newtree[num_fields - 1])) {
367 has_flexarray = true;
368 shuffle_length--;
369 }
370
371 shuffle(type, (tree *)newtree, shuffle_length);
372
373 /*
374 * set up a bogus anonymous struct field designed to error out on unnamed struct initializers
375 * as gcc provides no other way to detect such code
376 */
377 list = make_node(FIELD_DECL);
378 TREE_CHAIN(list) = newtree[0];
379 TREE_TYPE(list) = void_type_node;
380 DECL_SIZE(list) = bitsize_zero_node;
381 DECL_NONADDRESSABLE_P(list) = 1;
382 DECL_FIELD_BIT_OFFSET(list) = bitsize_zero_node;
383 DECL_SIZE_UNIT(list) = size_zero_node;
384 DECL_FIELD_OFFSET(list) = size_zero_node;
385 DECL_CONTEXT(list) = type;
386 // to satisfy the constify plugin
387 TREE_READONLY(list) = 1;
388
389 for (i = 0; i < num_fields - 1; i++)
390 TREE_CHAIN(newtree[i]) = newtree[i+1];
391 TREE_CHAIN(newtree[num_fields - 1]) = NULL_TREE;
392
393 main_variant = TYPE_MAIN_VARIANT(type);
394 for (variant = main_variant; variant; variant = TYPE_NEXT_VARIANT(variant)) {
395 TYPE_FIELDS(variant) = list;
396 TYPE_ATTRIBUTES(variant) = copy_list(TYPE_ATTRIBUTES(variant));
397 TYPE_ATTRIBUTES(variant) = tree_cons(get_identifier("randomize_performed"), NULL_TREE, TYPE_ATTRIBUTES(variant));
398 TYPE_ATTRIBUTES(variant) = tree_cons(get_identifier("designated_init"), NULL_TREE, TYPE_ATTRIBUTES(variant));
399 if (has_flexarray)
400 TYPE_ATTRIBUTES(type) = tree_cons(get_identifier("has_flexarray"), NULL_TREE, TYPE_ATTRIBUTES(type));
401 }
402
403 /*
404 * force a re-layout of the main variant
405 * the TYPE_SIZE for all variants will be recomputed
406 * by finalize_type_size()
407 */
408 TYPE_SIZE(main_variant) = NULL_TREE;
409 layout_type(main_variant);
410 gcc_assert(TYPE_SIZE(main_variant) != NULL_TREE);
411
412 return 1;
413}
414
415/* from constify plugin */
416static const_tree get_field_type(const_tree field)
417{
418 return strip_array_types(TREE_TYPE(field));
419}
420
421/* from constify plugin */
422static bool is_fptr(const_tree fieldtype)
423{
424 if (TREE_CODE(fieldtype) != POINTER_TYPE)
425 return false;
426
427 return TREE_CODE(TREE_TYPE(fieldtype)) == FUNCTION_TYPE;
428}
429
430/* derived from constify plugin */
431static int is_pure_ops_struct(const_tree node)
432{
433 const_tree field;
434
435 gcc_assert(TREE_CODE(node) == RECORD_TYPE || TREE_CODE(node) == UNION_TYPE);
436
313dd1b6
KC		 437 for (field = TYPE_FIELDS(node); field; field = TREE_CHAIN(field)) {
438 const_tree fieldtype = get_field_type(field);
439 enum tree_code code = TREE_CODE(fieldtype);
440
441 if (node == fieldtype)
442 continue;
443
60f2c82e
JK		 444 if (code == RECORD_TYPE || code == UNION_TYPE) {
445 if (!is_pure_ops_struct(fieldtype))
446 return 0;
313dd1b6 447 continue;
60f2c82e 448 }
313dd1b6 449
60f2c82e 450 if (!is_fptr(fieldtype))
313dd1b6
KC		 451 return 0;
452 }
453
454 return 1;
455}
456
457static void randomize_type(tree type)
458{
459 tree variant;
460
461 gcc_assert(TREE_CODE(type) == RECORD_TYPE);
462
463 if (lookup_attribute("randomize_considered", TYPE_ATTRIBUTES(type)))
464 return;
465
466 if (lookup_attribute("randomize_layout", TYPE_ATTRIBUTES(TYPE_MAIN_VARIANT(type))) || is_pure_ops_struct(type))
467 relayout_struct(type);
468
469 for (variant = TYPE_MAIN_VARIANT(type); variant; variant = TYPE_NEXT_VARIANT(variant)) {
470 TYPE_ATTRIBUTES(type) = copy_list(TYPE_ATTRIBUTES(type));
471 TYPE_ATTRIBUTES(type) = tree_cons(get_identifier("randomize_considered"), NULL_TREE, TYPE_ATTRIBUTES(type));
472 }
473#ifdef __DEBUG_PLUGIN
474 fprintf(stderr, "Marking randomize_considered on struct %s\n", ORIG_TYPE_NAME(type));
475#ifdef __DEBUG_VERBOSE
476 debug_tree(type);
477#endif
478#endif
479}
480
481static void update_decl_size(tree decl)
482{
483 tree lastval, lastidx, field, init, type, flexsize;
484 unsigned HOST_WIDE_INT len;
485
486 type = TREE_TYPE(decl);
487
488 if (!lookup_attribute("has_flexarray", TYPE_ATTRIBUTES(type)))
489 return;
490
491 init = DECL_INITIAL(decl);
492 if (init == NULL_TREE || init == error_mark_node)
493 return;
494
495 if (TREE_CODE(init) != CONSTRUCTOR)
496 return;
497
498 len = CONSTRUCTOR_NELTS(init);
499 if (!len)
500 return;
501
502 lastval = CONSTRUCTOR_ELT(init, CONSTRUCTOR_NELTS(init) - 1)->value;
503 lastidx = CONSTRUCTOR_ELT(init, CONSTRUCTOR_NELTS(init) - 1)->index;
504
505 for (field = TYPE_FIELDS(TREE_TYPE(decl)); TREE_CHAIN(field); field = TREE_CHAIN(field))
506 ;
507
508 if (lastidx != field)
509 return;
510
511 if (TREE_CODE(lastval) != STRING_CST) {
512 error("Only string constants are supported as initializers "
513 "for randomized structures with flexible arrays");
514 return;
515 }
516
517 flexsize = bitsize_int(TREE_STRING_LENGTH(lastval) *
518 tree_to_uhwi(TYPE_SIZE(TREE_TYPE(TREE_TYPE(lastval)))));
519
520 DECL_SIZE(decl) = size_binop(PLUS_EXPR, TYPE_SIZE(type), flexsize);
521
522 return;
523}
524
525
526static void randomize_layout_finish_decl(void *event_data, void *data)
527{
528 tree decl = (tree)event_data;
529 tree type;
530
531 if (decl == NULL_TREE || decl == error_mark_node)
532 return;
533
534 type = TREE_TYPE(decl);
535
536 if (TREE_CODE(decl) != VAR_DECL)
537 return;
538
539 if (TREE_CODE(type) != RECORD_TYPE && TREE_CODE(type) != UNION_TYPE)
540 return;
541
542 if (!lookup_attribute("randomize_performed", TYPE_ATTRIBUTES(type)))
543 return;
544
545 DECL_SIZE(decl) = 0;
546 DECL_SIZE_UNIT(decl) = 0;
547 SET_DECL_ALIGN(decl, 0);
548 SET_DECL_MODE (decl, VOIDmode);
549 SET_DECL_RTL(decl, 0);
550 update_decl_size(decl);
551 layout_decl(decl, 0);
552}
553
554static void finish_type(void *event_data, void *data)
555{
556 tree type = (tree)event_data;
557
558 if (type == NULL_TREE || type == error_mark_node)
559 return;
560
561 if (TREE_CODE(type) != RECORD_TYPE)
562 return;
563
564 if (TYPE_FIELDS(type) == NULL_TREE)
565 return;
566
567 if (lookup_attribute("randomize_considered", TYPE_ATTRIBUTES(type)))
568 return;
569
570#ifdef __DEBUG_PLUGIN
571 fprintf(stderr, "Calling randomize_type on %s\n", ORIG_TYPE_NAME(type));
572#endif
573#ifdef __DEBUG_VERBOSE
574 debug_tree(type);
575#endif
576 randomize_type(type);
577
578 return;
579}
580
b8672910
KC		 581static struct attribute_spec randomize_layout_attr = { };
582static struct attribute_spec no_randomize_layout_attr = { };
583static struct attribute_spec randomize_considered_attr = { };
584static struct attribute_spec randomize_performed_attr = { };
313dd1b6 585
b8672910
KC		 586static void register_attributes(void *event_data, void *data)
587{
588 randomize_layout_attr.name = "randomize_layout";
589 randomize_layout_attr.type_required = true;
590 randomize_layout_attr.handler = handle_randomize_layout_attr;
b8672910 591 randomize_layout_attr.affects_type_identity = true;
313dd1b6 592
b8672910
KC		 593 no_randomize_layout_attr.name = "no_randomize_layout";
594 no_randomize_layout_attr.type_required = true;
595 no_randomize_layout_attr.handler = handle_randomize_layout_attr;
b8672910 596 no_randomize_layout_attr.affects_type_identity = true;
313dd1b6 597
b8672910
KC		 598 randomize_considered_attr.name = "randomize_considered";
599 randomize_considered_attr.type_required = true;
600 randomize_considered_attr.handler = handle_randomize_considered_attr;
601
602 randomize_performed_attr.name = "randomize_performed";
603 randomize_performed_attr.type_required = true;
604 randomize_performed_attr.handler = handle_randomize_performed_attr;
313dd1b6 605
313dd1b6
KC		 606 register_attribute(&randomize_layout_attr);
607 register_attribute(&no_randomize_layout_attr);
608 register_attribute(&randomize_considered_attr);
609 register_attribute(&randomize_performed_attr);
610}
611
612static void check_bad_casts_in_constructor(tree var, tree init)
613{
614 unsigned HOST_WIDE_INT idx;
615 tree field, val;
616 tree field_type, val_type;
617
618 FOR_EACH_CONSTRUCTOR_ELT(CONSTRUCTOR_ELTS(init), idx, field, val) {
619 if (TREE_CODE(val) == CONSTRUCTOR) {
620 check_bad_casts_in_constructor(var, val);
621 continue;
622 }
623
624 /* pipacs' plugin creates franken-arrays that differ from those produced by
625 normal code which all have valid 'field' trees. work around this */
626 if (field == NULL_TREE)
627 continue;
628 field_type = TREE_TYPE(field);
629 val_type = TREE_TYPE(val);
630
631 if (TREE_CODE(field_type) != POINTER_TYPE || TREE_CODE(val_type) != POINTER_TYPE)
632 continue;
633
634 if (field_type == val_type)
635 continue;
636
637 field_type = TYPE_MAIN_VARIANT(strip_array_types(TYPE_MAIN_VARIANT(TREE_TYPE(field_type))));
638 val_type = TYPE_MAIN_VARIANT(strip_array_types(TYPE_MAIN_VARIANT(TREE_TYPE(val_type))));
639
640 if (field_type == void_type_node)
641 continue;
642 if (field_type == val_type)
643 continue;
644 if (TREE_CODE(val_type) != RECORD_TYPE)
645 continue;
646
647 if (!lookup_attribute("randomize_performed", TYPE_ATTRIBUTES(val_type)))
648 continue;
649 MISMATCH(DECL_SOURCE_LOCATION(var), "constructor\n", TYPE_MAIN_VARIANT(field_type), TYPE_MAIN_VARIANT(val_type));
650 }
651}
652
653/* derived from the constify plugin */
654static void check_global_variables(void *event_data, void *data)
655{
656 struct varpool_node *node;
657 tree init;
658
659 FOR_EACH_VARIABLE(node) {
660 tree var = NODE_DECL(node);
661 init = DECL_INITIAL(var);
662 if (init == NULL_TREE)
663 continue;
664
665 if (TREE_CODE(init) != CONSTRUCTOR)
666 continue;
667
668 check_bad_casts_in_constructor(var, init);
669 }
670}
671
672static bool dominated_by_is_err(const_tree rhs, basic_block bb)
673{
674 basic_block dom;
675 gimple dom_stmt;
676 gimple call_stmt;
677 const_tree dom_lhs;
678 const_tree poss_is_err_cond;
679 const_tree poss_is_err_func;
680 const_tree is_err_arg;
681
682 dom = get_immediate_dominator(CDI_DOMINATORS, bb);
683 if (!dom)
684 return false;
685
686 dom_stmt = last_stmt(dom);
687 if (!dom_stmt)
688 return false;
689
690 if (gimple_code(dom_stmt) != GIMPLE_COND)
691 return false;
692
693 if (gimple_cond_code(dom_stmt) != NE_EXPR)
694 return false;
695
696 if (!integer_zerop(gimple_cond_rhs(dom_stmt)))
697 return false;
698
699 poss_is_err_cond = gimple_cond_lhs(dom_stmt);
700
701 if (TREE_CODE(poss_is_err_cond) != SSA_NAME)
702 return false;
703
704 call_stmt = SSA_NAME_DEF_STMT(poss_is_err_cond);
705
706 if (gimple_code(call_stmt) != GIMPLE_CALL)
707 return false;
708
709 dom_lhs = gimple_get_lhs(call_stmt);
710 poss_is_err_func = gimple_call_fndecl(call_stmt);
711 if (!poss_is_err_func)
712 return false;
713 if (dom_lhs != poss_is_err_cond)
714 return false;
715 if (strcmp(DECL_NAME_POINTER(poss_is_err_func), "IS_ERR"))
716 return false;
717
718 is_err_arg = gimple_call_arg(call_stmt, 0);
719 if (!is_err_arg)
720 return false;
721
722 if (is_err_arg != rhs)
723 return false;
724
725 return true;
726}
727
728static void handle_local_var_initializers(void)
729{
730 tree var;
731 unsigned int i;
732
733 FOR_EACH_LOCAL_DECL(cfun, i, var) {
734 tree init = DECL_INITIAL(var);
735 if (!init)
736 continue;
737 if (TREE_CODE(init) != CONSTRUCTOR)
738 continue;
739 check_bad_casts_in_constructor(var, init);
740 }
741}
742
743static bool type_name_eq(gimple stmt, const_tree type_tree, const char *wanted_name)
744{
745 const char *type_name;
746
747 if (type_tree == NULL_TREE)
748 return false;
749
750 switch (TREE_CODE(type_tree)) {
751 case RECORD_TYPE:
752 type_name = TYPE_NAME_POINTER(type_tree);
753 break;
754 case INTEGER_TYPE:
755 if (TYPE_PRECISION(type_tree) == CHAR_TYPE_SIZE)
756 type_name = "char";
757 else {
758 INFORM(gimple_location(stmt), "found non-char INTEGER_TYPE cast comparison: %qT\n", type_tree);
759 debug_tree(type_tree);
760 return false;
761 }
762 break;
763 case POINTER_TYPE:
764 if (TREE_CODE(TREE_TYPE(type_tree)) == VOID_TYPE) {
765 type_name = "void *";
766 break;
767 } else {
768 INFORM(gimple_location(stmt), "found non-void POINTER_TYPE cast comparison %qT\n", type_tree);
769 debug_tree(type_tree);
770 return false;
771 }
772 default:
773 INFORM(gimple_location(stmt), "unhandled cast comparison: %qT\n", type_tree);
774 debug_tree(type_tree);
775 return false;
776 }
777
778 return strcmp(type_name, wanted_name) == 0;
779}
780
781static bool whitelisted_cast(gimple stmt, const_tree lhs_tree, const_tree rhs_tree)
782{
783 const struct whitelist_entry *entry;
784 expanded_location xloc = expand_location(gimple_location(stmt));
785
786 for (entry = whitelist; entry->pathname; entry++) {
787 if (!strstr(xloc.file, entry->pathname))
788 continue;
789
790 if (type_name_eq(stmt, lhs_tree, entry->lhs) && type_name_eq(stmt, rhs_tree, entry->rhs))
791 return true;
792 }
793
794 return false;
795}
796
797/*
798 * iterate over all statements to find "bad" casts:
799 * those where the address of the start of a structure is cast
800 * to a pointer of a structure of a different type, or a
801 * structure pointer type is cast to a different structure pointer type
802 */
803static unsigned int find_bad_casts_execute(void)
804{
805 basic_block bb;
806
807 handle_local_var_initializers();
808
809 FOR_EACH_BB_FN(bb, cfun) {
810 gimple_stmt_iterator gsi;
811
812 for (gsi = gsi_start_bb(bb); !gsi_end_p(gsi); gsi_next(&gsi)) {
813 gimple stmt;
814 const_tree lhs;
815 const_tree lhs_type;
816 const_tree rhs1;
817 const_tree rhs_type;
818 const_tree ptr_lhs_type;
819 const_tree ptr_rhs_type;
820 const_tree op0;
821 const_tree op0_type;
822 enum tree_code rhs_code;
823
824 stmt = gsi_stmt(gsi);
825
826#ifdef __DEBUG_PLUGIN
827#ifdef __DEBUG_VERBOSE
828 debug_gimple_stmt(stmt);
829 debug_tree(gimple_get_lhs(stmt));
830#endif
831#endif
832
833 if (gimple_code(stmt) != GIMPLE_ASSIGN)
834 continue;
835
836#ifdef __DEBUG_PLUGIN
837#ifdef __DEBUG_VERBOSE
838 debug_tree(gimple_assign_rhs1(stmt));
839#endif
840#endif
841
842
843 rhs_code = gimple_assign_rhs_code(stmt);
844
845 if (rhs_code != ADDR_EXPR && rhs_code != SSA_NAME)
846 continue;
847
848 lhs = gimple_get_lhs(stmt);
849 lhs_type = TREE_TYPE(lhs);
850 rhs1 = gimple_assign_rhs1(stmt);
851 rhs_type = TREE_TYPE(rhs1);
852
853 if (TREE_CODE(rhs_type) != POINTER_TYPE ||
854 TREE_CODE(lhs_type) != POINTER_TYPE)
855 continue;
856
857 ptr_lhs_type = TYPE_MAIN_VARIANT(strip_array_types(TYPE_MAIN_VARIANT(TREE_TYPE(lhs_type))));
858 ptr_rhs_type = TYPE_MAIN_VARIANT(strip_array_types(TYPE_MAIN_VARIANT(TREE_TYPE(rhs_type))));
859
860 if (ptr_rhs_type == void_type_node)
861 continue;
862
863 if (ptr_lhs_type == void_type_node)
864 continue;
865
866 if (dominated_by_is_err(rhs1, bb))
867 continue;
868
869 if (TREE_CODE(ptr_rhs_type) != RECORD_TYPE) {
870#ifndef __DEBUG_PLUGIN
871 if (lookup_attribute("randomize_performed", TYPE_ATTRIBUTES(ptr_lhs_type)))
872#endif
873 {
874 if (!whitelisted_cast(stmt, ptr_lhs_type, ptr_rhs_type))
875 MISMATCH(gimple_location(stmt), "rhs", ptr_lhs_type, ptr_rhs_type);
876 }
877 continue;
878 }
879
880 if (rhs_code == SSA_NAME && ptr_lhs_type == ptr_rhs_type)
881 continue;
882
883 if (rhs_code == ADDR_EXPR) {
884 op0 = TREE_OPERAND(rhs1, 0);
885
886 if (op0 == NULL_TREE)
887 continue;
888
889 if (TREE_CODE(op0) != VAR_DECL)
890 continue;
891
892 op0_type = TYPE_MAIN_VARIANT(strip_array_types(TYPE_MAIN_VARIANT(TREE_TYPE(op0))));
893 if (op0_type == ptr_lhs_type)
894 continue;
895
896#ifndef __DEBUG_PLUGIN
897 if (lookup_attribute("randomize_performed", TYPE_ATTRIBUTES(op0_type)))
898#endif
899 {
900 if (!whitelisted_cast(stmt, ptr_lhs_type, op0_type))
901 MISMATCH(gimple_location(stmt), "op0", ptr_lhs_type, op0_type);
902 }
903 } else {
904 const_tree ssa_name_var = SSA_NAME_VAR(rhs1);
905 /* skip bogus type casts introduced by container_of */
906 if (ssa_name_var != NULL_TREE && DECL_NAME(ssa_name_var) &&
907 !strcmp((const char *)DECL_NAME_POINTER(ssa_name_var), "__mptr"))
908 continue;
909#ifndef __DEBUG_PLUGIN
910 if (lookup_attribute("randomize_performed", TYPE_ATTRIBUTES(ptr_rhs_type)))
911#endif
912 {
913 if (!whitelisted_cast(stmt, ptr_lhs_type, ptr_rhs_type))
914 MISMATCH(gimple_location(stmt), "ssa", ptr_lhs_type, ptr_rhs_type);
915 }
916 }
917
918 }
919 }
920 return 0;
921}
922
923#define PASS_NAME find_bad_casts
924#define NO_GATE
925#define TODO_FLAGS_FINISH TODO_dump_func
926#include "gcc-generate-gimple-pass.h"
927
928__visible int plugin_init(struct plugin_name_args *plugin_info, struct plugin_gcc_version *version)
929{
930 int i;
931 const char * const plugin_name = plugin_info->base_name;
932 const int argc = plugin_info->argc;
933 const struct plugin_argument * const argv = plugin_info->argv;
934 bool enable = true;
935 int obtained_seed = 0;
936 struct register_pass_info find_bad_casts_pass_info;
937
938 find_bad_casts_pass_info.pass = make_find_bad_casts_pass();
939 find_bad_casts_pass_info.reference_pass_name = "ssa";
940 find_bad_casts_pass_info.ref_pass_instance_number = 1;
941 find_bad_casts_pass_info.pos_op = PASS_POS_INSERT_AFTER;
942
943 if (!plugin_default_version_check(version, &gcc_version)) {
944 error(G_("incompatible gcc/plugin versions"));
945 return 1;
946 }
947
948 if (strncmp(lang_hooks.name, "GNU C", 5) && !strncmp(lang_hooks.name, "GNU C+", 6)) {
949 inform(UNKNOWN_LOCATION, G_("%s supports C only, not %s"), plugin_name, lang_hooks.name);
950 enable = false;
951 }
952
953 for (i = 0; i < argc; ++i) {
954 if (!strcmp(argv[i].key, "disable")) {
955 enable = false;
956 continue;
957 }
958 if (!strcmp(argv[i].key, "performance-mode")) {
959 performance_mode = 1;
960 continue;
961 }
962 error(G_("unknown option '-fplugin-arg-%s-%s'"), plugin_name, argv[i].key);
963 }
964
965 if (strlen(randstruct_seed) != 64) {
966 error(G_("invalid seed value supplied for %s plugin"), plugin_name);
967 return 1;
968 }
969 obtained_seed = sscanf(randstruct_seed, "%016llx%016llx%016llx%016llx",
970 &shuffle_seed[0], &shuffle_seed[1], &shuffle_seed[2], &shuffle_seed[3]);
971 if (obtained_seed != 4) {
972 error(G_("Invalid seed supplied for %s plugin"), plugin_name);
973 return 1;
974 }
975
976 register_callback(plugin_name, PLUGIN_INFO, NULL, &randomize_layout_plugin_info);
977 if (enable) {
978 register_callback(plugin_name, PLUGIN_ALL_IPA_PASSES_START, check_global_variables, NULL);
979 register_callback(plugin_name, PLUGIN_PASS_MANAGER_SETUP, NULL, &find_bad_casts_pass_info);
980 register_callback(plugin_name, PLUGIN_FINISH_TYPE, finish_type, NULL);
981 register_callback(plugin_name, PLUGIN_FINISH_DECL, randomize_layout_finish_decl, NULL);
982 }
983 register_callback(plugin_name, PLUGIN_ATTRIBUTES, register_attributes, NULL);
984
985 return 0;
986}
Linux 6.x block layer and io_uring tree(s)