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niu: Silence randstruct warnings
[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 = {
61f60bac 37 .version = UTS_RELEASE,
313dd1b6
KC		 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[] = {
b07b6584
KC		 49 /* unix_skb_parms via UNIXCB() buffer */
50 { "net/unix/af_unix.c", "unix_skb_parms", "char" },
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
313dd1b6
KC		 433 for (field = TYPE_FIELDS(node); field; field = TREE_CHAIN(field)) {
434 const_tree fieldtype = get_field_type(field);
435 enum tree_code code = TREE_CODE(fieldtype);
436
437 if (node == fieldtype)
438 continue;
439
60f2c82e
JK		 440 if (code == RECORD_TYPE || code == UNION_TYPE) {
441 if (!is_pure_ops_struct(fieldtype))
442 return 0;
313dd1b6 443 continue;
60f2c82e 444 }
313dd1b6 445
60f2c82e 446 if (!is_fptr(fieldtype))
313dd1b6
KC		 447 return 0;
448 }
449
450 return 1;
451}
452
453static void randomize_type(tree type)
454{
455 tree variant;
456
457 gcc_assert(TREE_CODE(type) == RECORD_TYPE);
458
459 if (lookup_attribute("randomize_considered", TYPE_ATTRIBUTES(type)))
460 return;
461
462 if (lookup_attribute("randomize_layout", TYPE_ATTRIBUTES(TYPE_MAIN_VARIANT(type))) || is_pure_ops_struct(type))
463 relayout_struct(type);
464
465 for (variant = TYPE_MAIN_VARIANT(type); variant; variant = TYPE_NEXT_VARIANT(variant)) {
466 TYPE_ATTRIBUTES(type) = copy_list(TYPE_ATTRIBUTES(type));
467 TYPE_ATTRIBUTES(type) = tree_cons(get_identifier("randomize_considered"), NULL_TREE, TYPE_ATTRIBUTES(type));
468 }
469#ifdef __DEBUG_PLUGIN
470 fprintf(stderr, "Marking randomize_considered on struct %s\n", ORIG_TYPE_NAME(type));
471#ifdef __DEBUG_VERBOSE
472 debug_tree(type);
473#endif
474#endif
475}
476
477static void update_decl_size(tree decl)
478{
479 tree lastval, lastidx, field, init, type, flexsize;
480 unsigned HOST_WIDE_INT len;
481
482 type = TREE_TYPE(decl);
483
484 if (!lookup_attribute("has_flexarray", TYPE_ATTRIBUTES(type)))
485 return;
486
487 init = DECL_INITIAL(decl);
488 if (init == NULL_TREE || init == error_mark_node)
489 return;
490
491 if (TREE_CODE(init) != CONSTRUCTOR)
492 return;
493
494 len = CONSTRUCTOR_NELTS(init);
495 if (!len)
496 return;
497
498 lastval = CONSTRUCTOR_ELT(init, CONSTRUCTOR_NELTS(init) - 1)->value;
499 lastidx = CONSTRUCTOR_ELT(init, CONSTRUCTOR_NELTS(init) - 1)->index;
500
501 for (field = TYPE_FIELDS(TREE_TYPE(decl)); TREE_CHAIN(field); field = TREE_CHAIN(field))
502 ;
503
504 if (lastidx != field)
505 return;
506
507 if (TREE_CODE(lastval) != STRING_CST) {
508 error("Only string constants are supported as initializers "
509 "for randomized structures with flexible arrays");
510 return;
511 }
512
513 flexsize = bitsize_int(TREE_STRING_LENGTH(lastval) *
514 tree_to_uhwi(TYPE_SIZE(TREE_TYPE(TREE_TYPE(lastval)))));
515
516 DECL_SIZE(decl) = size_binop(PLUS_EXPR, TYPE_SIZE(type), flexsize);
517
518 return;
519}
520
521
522static void randomize_layout_finish_decl(void *event_data, void *data)
523{
524 tree decl = (tree)event_data;
525 tree type;
526
527 if (decl == NULL_TREE || decl == error_mark_node)
528 return;
529
530 type = TREE_TYPE(decl);
531
532 if (TREE_CODE(decl) != VAR_DECL)
533 return;
534
535 if (TREE_CODE(type) != RECORD_TYPE && TREE_CODE(type) != UNION_TYPE)
536 return;
537
538 if (!lookup_attribute("randomize_performed", TYPE_ATTRIBUTES(type)))
539 return;
540
541 DECL_SIZE(decl) = 0;
542 DECL_SIZE_UNIT(decl) = 0;
543 SET_DECL_ALIGN(decl, 0);
544 SET_DECL_MODE (decl, VOIDmode);
545 SET_DECL_RTL(decl, 0);
546 update_decl_size(decl);
547 layout_decl(decl, 0);
548}
549
550static void finish_type(void *event_data, void *data)
551{
552 tree type = (tree)event_data;
553
554 if (type == NULL_TREE || type == error_mark_node)
555 return;
556
557 if (TREE_CODE(type) != RECORD_TYPE)
558 return;
559
560 if (TYPE_FIELDS(type) == NULL_TREE)
561 return;
562
563 if (lookup_attribute("randomize_considered", TYPE_ATTRIBUTES(type)))
564 return;
565
566#ifdef __DEBUG_PLUGIN
567 fprintf(stderr, "Calling randomize_type on %s\n", ORIG_TYPE_NAME(type));
568#endif
569#ifdef __DEBUG_VERBOSE
570 debug_tree(type);
571#endif
572 randomize_type(type);
573
574 return;
575}
576
b8672910
KC		 577static struct attribute_spec randomize_layout_attr = { };
578static struct attribute_spec no_randomize_layout_attr = { };
579static struct attribute_spec randomize_considered_attr = { };
580static struct attribute_spec randomize_performed_attr = { };
313dd1b6 581
b8672910
KC		 582static void register_attributes(void *event_data, void *data)
583{
584 randomize_layout_attr.name = "randomize_layout";
585 randomize_layout_attr.type_required = true;
586 randomize_layout_attr.handler = handle_randomize_layout_attr;
b8672910 587 randomize_layout_attr.affects_type_identity = true;
313dd1b6 588
b8672910
KC		 589 no_randomize_layout_attr.name = "no_randomize_layout";
590 no_randomize_layout_attr.type_required = true;
591 no_randomize_layout_attr.handler = handle_randomize_layout_attr;
b8672910 592 no_randomize_layout_attr.affects_type_identity = true;
313dd1b6 593
b8672910
KC		 594 randomize_considered_attr.name = "randomize_considered";
595 randomize_considered_attr.type_required = true;
596 randomize_considered_attr.handler = handle_randomize_considered_attr;
597
598 randomize_performed_attr.name = "randomize_performed";
599 randomize_performed_attr.type_required = true;
600 randomize_performed_attr.handler = handle_randomize_performed_attr;
313dd1b6 601
313dd1b6
KC		 602 register_attribute(&randomize_layout_attr);
603 register_attribute(&no_randomize_layout_attr);
604 register_attribute(&randomize_considered_attr);
605 register_attribute(&randomize_performed_attr);
606}
607
608static void check_bad_casts_in_constructor(tree var, tree init)
609{
610 unsigned HOST_WIDE_INT idx;
611 tree field, val;
612 tree field_type, val_type;
613
614 FOR_EACH_CONSTRUCTOR_ELT(CONSTRUCTOR_ELTS(init), idx, field, val) {
615 if (TREE_CODE(val) == CONSTRUCTOR) {
616 check_bad_casts_in_constructor(var, val);
617 continue;
618 }
619
620 /* pipacs' plugin creates franken-arrays that differ from those produced by
621 normal code which all have valid 'field' trees. work around this */
622 if (field == NULL_TREE)
623 continue;
624 field_type = TREE_TYPE(field);
625 val_type = TREE_TYPE(val);
626
627 if (TREE_CODE(field_type) != POINTER_TYPE || TREE_CODE(val_type) != POINTER_TYPE)
628 continue;
629
630 if (field_type == val_type)
631 continue;
632
633 field_type = TYPE_MAIN_VARIANT(strip_array_types(TYPE_MAIN_VARIANT(TREE_TYPE(field_type))));
634 val_type = TYPE_MAIN_VARIANT(strip_array_types(TYPE_MAIN_VARIANT(TREE_TYPE(val_type))));
635
636 if (field_type == void_type_node)
637 continue;
638 if (field_type == val_type)
639 continue;
640 if (TREE_CODE(val_type) != RECORD_TYPE)
641 continue;
642
643 if (!lookup_attribute("randomize_performed", TYPE_ATTRIBUTES(val_type)))
644 continue;
645 MISMATCH(DECL_SOURCE_LOCATION(var), "constructor\n", TYPE_MAIN_VARIANT(field_type), TYPE_MAIN_VARIANT(val_type));
646 }
647}
648
649/* derived from the constify plugin */
650static void check_global_variables(void *event_data, void *data)
651{
652 struct varpool_node *node;
653 tree init;
654
655 FOR_EACH_VARIABLE(node) {
656 tree var = NODE_DECL(node);
657 init = DECL_INITIAL(var);
658 if (init == NULL_TREE)
659 continue;
660
661 if (TREE_CODE(init) != CONSTRUCTOR)
662 continue;
663
664 check_bad_casts_in_constructor(var, init);
665 }
666}
667
668static bool dominated_by_is_err(const_tree rhs, basic_block bb)
669{
670 basic_block dom;
671 gimple dom_stmt;
672 gimple call_stmt;
673 const_tree dom_lhs;
674 const_tree poss_is_err_cond;
675 const_tree poss_is_err_func;
676 const_tree is_err_arg;
677
678 dom = get_immediate_dominator(CDI_DOMINATORS, bb);
679 if (!dom)
680 return false;
681
682 dom_stmt = last_stmt(dom);
683 if (!dom_stmt)
684 return false;
685
686 if (gimple_code(dom_stmt) != GIMPLE_COND)
687 return false;
688
689 if (gimple_cond_code(dom_stmt) != NE_EXPR)
690 return false;
691
692 if (!integer_zerop(gimple_cond_rhs(dom_stmt)))
693 return false;
694
695 poss_is_err_cond = gimple_cond_lhs(dom_stmt);
696
697 if (TREE_CODE(poss_is_err_cond) != SSA_NAME)
698 return false;
699
700 call_stmt = SSA_NAME_DEF_STMT(poss_is_err_cond);
701
702 if (gimple_code(call_stmt) != GIMPLE_CALL)
703 return false;
704
705 dom_lhs = gimple_get_lhs(call_stmt);
706 poss_is_err_func = gimple_call_fndecl(call_stmt);
707 if (!poss_is_err_func)
708 return false;
709 if (dom_lhs != poss_is_err_cond)
710 return false;
711 if (strcmp(DECL_NAME_POINTER(poss_is_err_func), "IS_ERR"))
712 return false;
713
714 is_err_arg = gimple_call_arg(call_stmt, 0);
715 if (!is_err_arg)
716 return false;
717
718 if (is_err_arg != rhs)
719 return false;
720
721 return true;
722}
723
724static void handle_local_var_initializers(void)
725{
726 tree var;
727 unsigned int i;
728
729 FOR_EACH_LOCAL_DECL(cfun, i, var) {
730 tree init = DECL_INITIAL(var);
731 if (!init)
732 continue;
733 if (TREE_CODE(init) != CONSTRUCTOR)
734 continue;
735 check_bad_casts_in_constructor(var, init);
736 }
737}
738
739static bool type_name_eq(gimple stmt, const_tree type_tree, const char *wanted_name)
740{
741 const char *type_name;
742
743 if (type_tree == NULL_TREE)
744 return false;
745
746 switch (TREE_CODE(type_tree)) {
747 case RECORD_TYPE:
748 type_name = TYPE_NAME_POINTER(type_tree);
749 break;
750 case INTEGER_TYPE:
751 if (TYPE_PRECISION(type_tree) == CHAR_TYPE_SIZE)
752 type_name = "char";
753 else {
754 INFORM(gimple_location(stmt), "found non-char INTEGER_TYPE cast comparison: %qT\n", type_tree);
755 debug_tree(type_tree);
756 return false;
757 }
758 break;
759 case POINTER_TYPE:
760 if (TREE_CODE(TREE_TYPE(type_tree)) == VOID_TYPE) {
761 type_name = "void *";
762 break;
763 } else {
764 INFORM(gimple_location(stmt), "found non-void POINTER_TYPE cast comparison %qT\n", type_tree);
765 debug_tree(type_tree);
766 return false;
767 }
768 default:
769 INFORM(gimple_location(stmt), "unhandled cast comparison: %qT\n", type_tree);
770 debug_tree(type_tree);
771 return false;
772 }
773
774 return strcmp(type_name, wanted_name) == 0;
775}
776
777static bool whitelisted_cast(gimple stmt, const_tree lhs_tree, const_tree rhs_tree)
778{
779 const struct whitelist_entry *entry;
780 expanded_location xloc = expand_location(gimple_location(stmt));
781
782 for (entry = whitelist; entry->pathname; entry++) {
783 if (!strstr(xloc.file, entry->pathname))
784 continue;
785
786 if (type_name_eq(stmt, lhs_tree, entry->lhs) && type_name_eq(stmt, rhs_tree, entry->rhs))
787 return true;
788 }
789
790 return false;
791}
792
793/*
794 * iterate over all statements to find "bad" casts:
795 * those where the address of the start of a structure is cast
796 * to a pointer of a structure of a different type, or a
797 * structure pointer type is cast to a different structure pointer type
798 */
799static unsigned int find_bad_casts_execute(void)
800{
801 basic_block bb;
802
803 handle_local_var_initializers();
804
805 FOR_EACH_BB_FN(bb, cfun) {
806 gimple_stmt_iterator gsi;
807
808 for (gsi = gsi_start_bb(bb); !gsi_end_p(gsi); gsi_next(&gsi)) {
809 gimple stmt;
810 const_tree lhs;
811 const_tree lhs_type;
812 const_tree rhs1;
813 const_tree rhs_type;
814 const_tree ptr_lhs_type;
815 const_tree ptr_rhs_type;
816 const_tree op0;
817 const_tree op0_type;
818 enum tree_code rhs_code;
819
820 stmt = gsi_stmt(gsi);
821
822#ifdef __DEBUG_PLUGIN
823#ifdef __DEBUG_VERBOSE
824 debug_gimple_stmt(stmt);
825 debug_tree(gimple_get_lhs(stmt));
826#endif
827#endif
828
829 if (gimple_code(stmt) != GIMPLE_ASSIGN)
830 continue;
831
832#ifdef __DEBUG_PLUGIN
833#ifdef __DEBUG_VERBOSE
834 debug_tree(gimple_assign_rhs1(stmt));
835#endif
836#endif
837
838
839 rhs_code = gimple_assign_rhs_code(stmt);
840
841 if (rhs_code != ADDR_EXPR && rhs_code != SSA_NAME)
842 continue;
843
844 lhs = gimple_get_lhs(stmt);
845 lhs_type = TREE_TYPE(lhs);
846 rhs1 = gimple_assign_rhs1(stmt);
847 rhs_type = TREE_TYPE(rhs1);
848
849 if (TREE_CODE(rhs_type) != POINTER_TYPE ||
850 TREE_CODE(lhs_type) != POINTER_TYPE)
851 continue;
852
853 ptr_lhs_type = TYPE_MAIN_VARIANT(strip_array_types(TYPE_MAIN_VARIANT(TREE_TYPE(lhs_type))));
854 ptr_rhs_type = TYPE_MAIN_VARIANT(strip_array_types(TYPE_MAIN_VARIANT(TREE_TYPE(rhs_type))));
855
856 if (ptr_rhs_type == void_type_node)
857 continue;
858
859 if (ptr_lhs_type == void_type_node)
860 continue;
861
862 if (dominated_by_is_err(rhs1, bb))
863 continue;
864
865 if (TREE_CODE(ptr_rhs_type) != RECORD_TYPE) {
866#ifndef __DEBUG_PLUGIN
867 if (lookup_attribute("randomize_performed", TYPE_ATTRIBUTES(ptr_lhs_type)))
868#endif
869 {
870 if (!whitelisted_cast(stmt, ptr_lhs_type, ptr_rhs_type))
871 MISMATCH(gimple_location(stmt), "rhs", ptr_lhs_type, ptr_rhs_type);
872 }
873 continue;
874 }
875
876 if (rhs_code == SSA_NAME && ptr_lhs_type == ptr_rhs_type)
877 continue;
878
879 if (rhs_code == ADDR_EXPR) {
880 op0 = TREE_OPERAND(rhs1, 0);
881
882 if (op0 == NULL_TREE)
883 continue;
884
885 if (TREE_CODE(op0) != VAR_DECL)
886 continue;
887
888 op0_type = TYPE_MAIN_VARIANT(strip_array_types(TYPE_MAIN_VARIANT(TREE_TYPE(op0))));
889 if (op0_type == ptr_lhs_type)
890 continue;
891
892#ifndef __DEBUG_PLUGIN
893 if (lookup_attribute("randomize_performed", TYPE_ATTRIBUTES(op0_type)))
894#endif
895 {
896 if (!whitelisted_cast(stmt, ptr_lhs_type, op0_type))
897 MISMATCH(gimple_location(stmt), "op0", ptr_lhs_type, op0_type);
898 }
899 } else {
900 const_tree ssa_name_var = SSA_NAME_VAR(rhs1);
901 /* skip bogus type casts introduced by container_of */
902 if (ssa_name_var != NULL_TREE && DECL_NAME(ssa_name_var) &&
903 !strcmp((const char *)DECL_NAME_POINTER(ssa_name_var), "__mptr"))
904 continue;
905#ifndef __DEBUG_PLUGIN
906 if (lookup_attribute("randomize_performed", TYPE_ATTRIBUTES(ptr_rhs_type)))
907#endif
908 {
909 if (!whitelisted_cast(stmt, ptr_lhs_type, ptr_rhs_type))
910 MISMATCH(gimple_location(stmt), "ssa", ptr_lhs_type, ptr_rhs_type);
911 }
912 }
913
914 }
915 }
916 return 0;
917}
918
919#define PASS_NAME find_bad_casts
920#define NO_GATE
921#define TODO_FLAGS_FINISH TODO_dump_func
922#include "gcc-generate-gimple-pass.h"
923
924__visible int plugin_init(struct plugin_name_args *plugin_info, struct plugin_gcc_version *version)
925{
926 int i;
927 const char * const plugin_name = plugin_info->base_name;
928 const int argc = plugin_info->argc;
929 const struct plugin_argument * const argv = plugin_info->argv;
930 bool enable = true;
931 int obtained_seed = 0;
932 struct register_pass_info find_bad_casts_pass_info;
933
934 find_bad_casts_pass_info.pass = make_find_bad_casts_pass();
935 find_bad_casts_pass_info.reference_pass_name = "ssa";
936 find_bad_casts_pass_info.ref_pass_instance_number = 1;
937 find_bad_casts_pass_info.pos_op = PASS_POS_INSERT_AFTER;
938
939 if (!plugin_default_version_check(version, &gcc_version)) {
940 error(G_("incompatible gcc/plugin versions"));
941 return 1;
942 }
943
944 if (strncmp(lang_hooks.name, "GNU C", 5) && !strncmp(lang_hooks.name, "GNU C+", 6)) {
945 inform(UNKNOWN_LOCATION, G_("%s supports C only, not %s"), plugin_name, lang_hooks.name);
946 enable = false;
947 }
948
949 for (i = 0; i < argc; ++i) {
950 if (!strcmp(argv[i].key, "disable")) {
951 enable = false;
952 continue;
953 }
954 if (!strcmp(argv[i].key, "performance-mode")) {
955 performance_mode = 1;
956 continue;
957 }
958 error(G_("unknown option '-fplugin-arg-%s-%s'"), plugin_name, argv[i].key);
959 }
960
961 if (strlen(randstruct_seed) != 64) {
962 error(G_("invalid seed value supplied for %s plugin"), plugin_name);
963 return 1;
964 }
965 obtained_seed = sscanf(randstruct_seed, "%016llx%016llx%016llx%016llx",
966 &shuffle_seed[0], &shuffle_seed[1], &shuffle_seed[2], &shuffle_seed[3]);
967 if (obtained_seed != 4) {
968 error(G_("Invalid seed supplied for %s plugin"), plugin_name);
969 return 1;
970 }
971
972 register_callback(plugin_name, PLUGIN_INFO, NULL, &randomize_layout_plugin_info);
973 if (enable) {
974 register_callback(plugin_name, PLUGIN_ALL_IPA_PASSES_START, check_global_variables, NULL);
975 register_callback(plugin_name, PLUGIN_PASS_MANAGER_SETUP, NULL, &find_bad_casts_pass_info);
976 register_callback(plugin_name, PLUGIN_FINISH_TYPE, finish_type, NULL);
977 register_callback(plugin_name, PLUGIN_FINISH_DECL, randomize_layout_finish_decl, NULL);
978 }
979 register_callback(plugin_name, PLUGIN_ATTRIBUTES, register_attributes, NULL);
980
981 return 0;
982}
Linux 6.x block layer and io_uring tree(s)