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 | |
34 | static int performance_mode; |
35 | |
36 | static struct plugin_info randomize_layout_plugin_info = { |
37 | .version = PLUGIN_VERSION, |
38 | .help = "disable\t\t\tdo not activate plugin\n" |
39 | "performance-mode\tenable cacheline-aware layout randomization\n" |
40 | }; |
41 | |
42 | /* from old Linux dcache.h */ |
43 | static inline unsigned long |
44 | partial_name_hash(unsigned long c, unsigned long prevhash) |
45 | { |
46 | return (prevhash + (c << 4) + (c >> 4)) * 11; |
47 | } |
48 | static inline unsigned int |
49 | name_hash(const unsigned char *name) |
50 | { |
51 | unsigned long hash = 0; |
52 | unsigned int len = strlen((const char *)name); |
53 | while (len--) |
54 | hash = partial_name_hash(c: *name++, prevhash: hash); |
55 | return (unsigned int)hash; |
56 | } |
57 | |
58 | static tree handle_randomize_layout_attr(tree *node, tree name, tree args, int flags, bool *no_add_attrs) |
59 | { |
60 | tree type; |
61 | |
62 | *no_add_attrs = true; |
63 | if (TREE_CODE(*node) == FUNCTION_DECL) { |
64 | error("%qE attribute does not apply to functions (%qF)" , name, *node); |
65 | return NULL_TREE; |
66 | } |
67 | |
68 | if (TREE_CODE(*node) == PARM_DECL) { |
69 | error("%qE attribute does not apply to function parameters (%qD)" , name, *node); |
70 | return NULL_TREE; |
71 | } |
72 | |
73 | if (TREE_CODE(*node) == VAR_DECL) { |
74 | error("%qE attribute does not apply to variables (%qD)" , name, *node); |
75 | return NULL_TREE; |
76 | } |
77 | |
78 | if (TYPE_P(*node)) { |
79 | type = *node; |
80 | } else { |
81 | gcc_assert(TREE_CODE(*node) == TYPE_DECL); |
82 | type = TREE_TYPE(*node); |
83 | } |
84 | |
85 | if (TREE_CODE(type) != RECORD_TYPE) { |
86 | error("%qE attribute used on %qT applies to struct types only" , name, type); |
87 | return NULL_TREE; |
88 | } |
89 | |
90 | if (lookup_attribute(IDENTIFIER_POINTER(name), TYPE_ATTRIBUTES(type))) { |
91 | error("%qE attribute is already applied to the type %qT" , name, type); |
92 | return NULL_TREE; |
93 | } |
94 | |
95 | *no_add_attrs = false; |
96 | |
97 | return NULL_TREE; |
98 | } |
99 | |
100 | /* set on complete types that we don't need to inspect further at all */ |
101 | static tree handle_randomize_considered_attr(tree *node, tree name, tree args, int flags, bool *no_add_attrs) |
102 | { |
103 | *no_add_attrs = false; |
104 | return NULL_TREE; |
105 | } |
106 | |
107 | /* |
108 | * set on types that we've performed a shuffle on, to prevent re-shuffling |
109 | * this does not preclude us from inspecting its fields for potential shuffles |
110 | */ |
111 | static tree handle_randomize_performed_attr(tree *node, tree name, tree args, int flags, bool *no_add_attrs) |
112 | { |
113 | *no_add_attrs = false; |
114 | return NULL_TREE; |
115 | } |
116 | |
117 | /* |
118 | * 64bit variant of Bob Jenkins' public domain PRNG |
119 | * 256 bits of internal state |
120 | */ |
121 | |
122 | typedef unsigned long long u64; |
123 | |
124 | typedef struct ranctx { u64 a; u64 b; u64 c; u64 d; } ranctx; |
125 | |
126 | #define rot(x,k) (((x)<<(k))|((x)>>(64-(k)))) |
127 | static u64 ranval(ranctx *x) { |
128 | u64 e = x->a - rot(x->b, 7); |
129 | x->a = x->b ^ rot(x->c, 13); |
130 | x->b = x->c + rot(x->d, 37); |
131 | x->c = x->d + e; |
132 | x->d = e + x->a; |
133 | return x->d; |
134 | } |
135 | |
136 | static void raninit(ranctx *x, u64 *seed) { |
137 | int i; |
138 | |
139 | x->a = seed[0]; |
140 | x->b = seed[1]; |
141 | x->c = seed[2]; |
142 | x->d = seed[3]; |
143 | |
144 | for (i=0; i < 30; ++i) |
145 | (void)ranval(x); |
146 | } |
147 | |
148 | static u64 shuffle_seed[4]; |
149 | |
150 | struct partition_group { |
151 | tree tree_start; |
152 | unsigned long start; |
153 | unsigned long length; |
154 | }; |
155 | |
156 | static void partition_struct(tree *fields, unsigned long length, struct partition_group *size_groups, unsigned long *num_groups) |
157 | { |
158 | unsigned long i; |
159 | unsigned long accum_size = 0; |
160 | unsigned long accum_length = 0; |
161 | unsigned long group_idx = 0; |
162 | |
163 | gcc_assert(length < INT_MAX); |
164 | |
165 | memset(size_groups, 0, sizeof(struct partition_group) * length); |
166 | |
167 | for (i = 0; i < length; i++) { |
168 | if (size_groups[group_idx].tree_start == NULL_TREE) { |
169 | size_groups[group_idx].tree_start = fields[i]; |
170 | size_groups[group_idx].start = i; |
171 | accum_length = 0; |
172 | accum_size = 0; |
173 | } |
174 | accum_size += (unsigned long)int_size_in_bytes(TREE_TYPE(fields[i])); |
175 | accum_length++; |
176 | if (accum_size >= 64) { |
177 | size_groups[group_idx].length = accum_length; |
178 | accum_length = 0; |
179 | group_idx++; |
180 | } |
181 | } |
182 | |
183 | if (size_groups[group_idx].tree_start != NULL_TREE && |
184 | !size_groups[group_idx].length) { |
185 | size_groups[group_idx].length = accum_length; |
186 | group_idx++; |
187 | } |
188 | |
189 | *num_groups = group_idx; |
190 | } |
191 | |
192 | static void performance_shuffle(tree *newtree, unsigned long length, ranctx *prng_state) |
193 | { |
194 | unsigned long i, x, index; |
195 | struct partition_group size_group[length]; |
196 | unsigned long num_groups = 0; |
197 | unsigned long randnum; |
198 | |
199 | partition_struct(newtree, length, (struct partition_group *)&size_group, &num_groups); |
200 | |
201 | /* FIXME: this group shuffle is currently a no-op. */ |
202 | for (i = num_groups - 1; i > 0; i--) { |
203 | struct partition_group tmp; |
204 | randnum = ranval(x: prng_state) % (i + 1); |
205 | tmp = size_group[i]; |
206 | size_group[i] = size_group[randnum]; |
207 | size_group[randnum] = tmp; |
208 | } |
209 | |
210 | for (x = 0; x < num_groups; x++) { |
211 | for (index = size_group[x].length - 1; index > 0; index--) { |
212 | tree tmp; |
213 | |
214 | i = size_group[x].start + index; |
215 | if (DECL_BIT_FIELD_TYPE(newtree[i])) |
216 | continue; |
217 | randnum = ranval(x: prng_state) % (index + 1); |
218 | randnum += size_group[x].start; |
219 | // we could handle this case differently if desired |
220 | if (DECL_BIT_FIELD_TYPE(newtree[randnum])) |
221 | continue; |
222 | tmp = newtree[i]; |
223 | newtree[i] = newtree[randnum]; |
224 | newtree[randnum] = tmp; |
225 | } |
226 | } |
227 | } |
228 | |
229 | static void full_shuffle(tree *newtree, unsigned long length, ranctx *prng_state) |
230 | { |
231 | unsigned long i, randnum; |
232 | |
233 | for (i = length - 1; i > 0; i--) { |
234 | tree tmp; |
235 | randnum = ranval(x: prng_state) % (i + 1); |
236 | tmp = newtree[i]; |
237 | newtree[i] = newtree[randnum]; |
238 | newtree[randnum] = tmp; |
239 | } |
240 | } |
241 | |
242 | /* modern in-place Fisher-Yates shuffle */ |
243 | static void shuffle(const_tree type, tree *newtree, unsigned long length) |
244 | { |
245 | unsigned long i; |
246 | u64 seed[4]; |
247 | ranctx prng_state; |
248 | const unsigned char *structname; |
249 | |
250 | if (length == 0) |
251 | return; |
252 | |
253 | gcc_assert(TREE_CODE(type) == RECORD_TYPE); |
254 | |
255 | structname = ORIG_TYPE_NAME(type); |
256 | |
257 | #ifdef __DEBUG_PLUGIN |
258 | fprintf(stderr, "Shuffling struct %s %p\n" , (const char *)structname, type); |
259 | #ifdef __DEBUG_VERBOSE |
260 | debug_tree((tree)type); |
261 | #endif |
262 | #endif |
263 | |
264 | for (i = 0; i < 4; i++) { |
265 | seed[i] = shuffle_seed[i]; |
266 | seed[i] ^= name_hash(name: structname); |
267 | } |
268 | |
269 | raninit(x: &prng_state, seed: (u64 *)&seed); |
270 | |
271 | if (performance_mode) |
272 | performance_shuffle(newtree, length, &prng_state); |
273 | else |
274 | full_shuffle(newtree, length, &prng_state); |
275 | } |
276 | |
277 | static bool is_flexible_array(const_tree field) |
278 | { |
279 | const_tree fieldtype; |
280 | const_tree typesize; |
281 | |
282 | fieldtype = TREE_TYPE(field); |
283 | typesize = TYPE_SIZE(fieldtype); |
284 | |
285 | if (TREE_CODE(fieldtype) != ARRAY_TYPE) |
286 | return false; |
287 | |
288 | /* size of type is represented in bits */ |
289 | |
290 | if (typesize == NULL_TREE && TYPE_DOMAIN(fieldtype) != NULL_TREE && |
291 | TYPE_MAX_VALUE(TYPE_DOMAIN(fieldtype)) == NULL_TREE) |
292 | return true; |
293 | |
294 | return false; |
295 | } |
296 | |
297 | static int relayout_struct(tree type) |
298 | { |
299 | unsigned long num_fields = (unsigned long)list_length(TYPE_FIELDS(type)); |
300 | unsigned long shuffle_length = num_fields; |
301 | tree field; |
302 | tree newtree[num_fields]; |
303 | unsigned long i; |
304 | tree list; |
305 | tree variant; |
306 | tree main_variant; |
307 | expanded_location xloc; |
308 | bool has_flexarray = false; |
309 | |
310 | if (TYPE_FIELDS(type) == NULL_TREE) |
311 | return 0; |
312 | |
313 | if (num_fields < 2) |
314 | return 0; |
315 | |
316 | gcc_assert(TREE_CODE(type) == RECORD_TYPE); |
317 | |
318 | gcc_assert(num_fields < INT_MAX); |
319 | |
320 | if (lookup_attribute("randomize_performed" , TYPE_ATTRIBUTES(type)) || |
321 | lookup_attribute("no_randomize_layout" , TYPE_ATTRIBUTES(TYPE_MAIN_VARIANT(type)))) |
322 | return 0; |
323 | |
324 | /* Workaround for 3rd-party VirtualBox source that we can't modify ourselves */ |
325 | if (!strcmp((const char *)ORIG_TYPE_NAME(type), "INTNETTRUNKFACTORY" ) || |
326 | !strcmp((const char *)ORIG_TYPE_NAME(type), "RAWPCIFACTORY" )) |
327 | return 0; |
328 | |
329 | /* throw out any structs in uapi */ |
330 | xloc = expand_location(DECL_SOURCE_LOCATION(TYPE_FIELDS(type))); |
331 | |
332 | if (strstr(xloc.file, "/uapi/" )) |
333 | error(G_("attempted to randomize userland API struct %s" ), ORIG_TYPE_NAME(type)); |
334 | |
335 | for (field = TYPE_FIELDS(type), i = 0; field; field = TREE_CHAIN(field), i++) { |
336 | gcc_assert(TREE_CODE(field) == FIELD_DECL); |
337 | newtree[i] = field; |
338 | } |
339 | |
340 | /* |
341 | * enforce that we don't randomize the layout of the last |
342 | * element of a struct if it's a proper flexible array |
343 | */ |
344 | if (is_flexible_array(newtree[num_fields - 1])) { |
345 | has_flexarray = true; |
346 | shuffle_length--; |
347 | } |
348 | |
349 | shuffle(type, (tree *)newtree, shuffle_length); |
350 | |
351 | /* |
352 | * set up a bogus anonymous struct field designed to error out on unnamed struct initializers |
353 | * as gcc provides no other way to detect such code |
354 | */ |
355 | list = make_node(FIELD_DECL); |
356 | TREE_CHAIN(list) = newtree[0]; |
357 | TREE_TYPE(list) = void_type_node; |
358 | DECL_SIZE(list) = bitsize_zero_node; |
359 | DECL_NONADDRESSABLE_P(list) = 1; |
360 | DECL_FIELD_BIT_OFFSET(list) = bitsize_zero_node; |
361 | DECL_SIZE_UNIT(list) = size_zero_node; |
362 | DECL_FIELD_OFFSET(list) = size_zero_node; |
363 | DECL_CONTEXT(list) = type; |
364 | // to satisfy the constify plugin |
365 | TREE_READONLY(list) = 1; |
366 | |
367 | for (i = 0; i < num_fields - 1; i++) |
368 | TREE_CHAIN(newtree[i]) = newtree[i+1]; |
369 | TREE_CHAIN(newtree[num_fields - 1]) = NULL_TREE; |
370 | |
371 | main_variant = TYPE_MAIN_VARIANT(type); |
372 | for (variant = main_variant; variant; variant = TYPE_NEXT_VARIANT(variant)) { |
373 | TYPE_FIELDS(variant) = list; |
374 | TYPE_ATTRIBUTES(variant) = copy_list(TYPE_ATTRIBUTES(variant)); |
375 | TYPE_ATTRIBUTES(variant) = tree_cons(get_identifier("randomize_performed" ), NULL_TREE, TYPE_ATTRIBUTES(variant)); |
376 | TYPE_ATTRIBUTES(variant) = tree_cons(get_identifier("designated_init" ), NULL_TREE, TYPE_ATTRIBUTES(variant)); |
377 | if (has_flexarray) |
378 | TYPE_ATTRIBUTES(type) = tree_cons(get_identifier("has_flexarray" ), NULL_TREE, TYPE_ATTRIBUTES(type)); |
379 | } |
380 | |
381 | /* |
382 | * force a re-layout of the main variant |
383 | * the TYPE_SIZE for all variants will be recomputed |
384 | * by finalize_type_size() |
385 | */ |
386 | TYPE_SIZE(main_variant) = NULL_TREE; |
387 | layout_type(main_variant); |
388 | gcc_assert(TYPE_SIZE(main_variant) != NULL_TREE); |
389 | |
390 | return 1; |
391 | } |
392 | |
393 | /* from constify plugin */ |
394 | static const_tree get_field_type(const_tree field) |
395 | { |
396 | return strip_array_types(TREE_TYPE(field)); |
397 | } |
398 | |
399 | /* from constify plugin */ |
400 | static bool is_fptr(const_tree fieldtype) |
401 | { |
402 | if (TREE_CODE(fieldtype) != POINTER_TYPE) |
403 | return false; |
404 | |
405 | return TREE_CODE(TREE_TYPE(fieldtype)) == FUNCTION_TYPE; |
406 | } |
407 | |
408 | /* derived from constify plugin */ |
409 | static int is_pure_ops_struct(const_tree node) |
410 | { |
411 | const_tree field; |
412 | |
413 | gcc_assert(TREE_CODE(node) == RECORD_TYPE || TREE_CODE(node) == UNION_TYPE); |
414 | |
415 | for (field = TYPE_FIELDS(node); field; field = TREE_CHAIN(field)) { |
416 | const_tree fieldtype = get_field_type(field); |
417 | enum tree_code code = TREE_CODE(fieldtype); |
418 | |
419 | if (node == fieldtype) |
420 | continue; |
421 | |
422 | if (code == RECORD_TYPE || code == UNION_TYPE) { |
423 | if (!is_pure_ops_struct(fieldtype)) |
424 | return 0; |
425 | continue; |
426 | } |
427 | |
428 | if (!is_fptr(fieldtype)) |
429 | return 0; |
430 | } |
431 | |
432 | return 1; |
433 | } |
434 | |
435 | static void randomize_type(tree type) |
436 | { |
437 | tree variant; |
438 | |
439 | gcc_assert(TREE_CODE(type) == RECORD_TYPE); |
440 | |
441 | if (lookup_attribute("randomize_considered" , TYPE_ATTRIBUTES(type))) |
442 | return; |
443 | |
444 | if (lookup_attribute("randomize_layout" , TYPE_ATTRIBUTES(TYPE_MAIN_VARIANT(type))) || is_pure_ops_struct(type)) |
445 | relayout_struct(type); |
446 | |
447 | for (variant = TYPE_MAIN_VARIANT(type); variant; variant = TYPE_NEXT_VARIANT(variant)) { |
448 | TYPE_ATTRIBUTES(type) = copy_list(TYPE_ATTRIBUTES(type)); |
449 | TYPE_ATTRIBUTES(type) = tree_cons(get_identifier("randomize_considered" ), NULL_TREE, TYPE_ATTRIBUTES(type)); |
450 | } |
451 | #ifdef __DEBUG_PLUGIN |
452 | fprintf(stderr, "Marking randomize_considered on struct %s\n" , ORIG_TYPE_NAME(type)); |
453 | #ifdef __DEBUG_VERBOSE |
454 | debug_tree(type); |
455 | #endif |
456 | #endif |
457 | } |
458 | |
459 | static void update_decl_size(tree decl) |
460 | { |
461 | tree lastval, lastidx, field, init, type, flexsize; |
462 | unsigned HOST_WIDE_INT len; |
463 | |
464 | type = TREE_TYPE(decl); |
465 | |
466 | if (!lookup_attribute("has_flexarray" , TYPE_ATTRIBUTES(type))) |
467 | return; |
468 | |
469 | init = DECL_INITIAL(decl); |
470 | if (init == NULL_TREE || init == error_mark_node) |
471 | return; |
472 | |
473 | if (TREE_CODE(init) != CONSTRUCTOR) |
474 | return; |
475 | |
476 | len = CONSTRUCTOR_NELTS(init); |
477 | if (!len) |
478 | return; |
479 | |
480 | lastval = CONSTRUCTOR_ELT(init, CONSTRUCTOR_NELTS(init) - 1)->value; |
481 | lastidx = CONSTRUCTOR_ELT(init, CONSTRUCTOR_NELTS(init) - 1)->index; |
482 | |
483 | for (field = TYPE_FIELDS(TREE_TYPE(decl)); TREE_CHAIN(field); field = TREE_CHAIN(field)) |
484 | ; |
485 | |
486 | if (lastidx != field) |
487 | return; |
488 | |
489 | if (TREE_CODE(lastval) != STRING_CST) { |
490 | error("Only string constants are supported as initializers " |
491 | "for randomized structures with flexible arrays" ); |
492 | return; |
493 | } |
494 | |
495 | flexsize = bitsize_int(TREE_STRING_LENGTH(lastval) * |
496 | tree_to_uhwi(TYPE_SIZE(TREE_TYPE(TREE_TYPE(lastval))))); |
497 | |
498 | DECL_SIZE(decl) = size_binop(PLUS_EXPR, TYPE_SIZE(type), flexsize); |
499 | |
500 | return; |
501 | } |
502 | |
503 | |
504 | static void randomize_layout_finish_decl(void *event_data, void *data) |
505 | { |
506 | tree decl = (tree)event_data; |
507 | tree type; |
508 | |
509 | if (decl == NULL_TREE || decl == error_mark_node) |
510 | return; |
511 | |
512 | type = TREE_TYPE(decl); |
513 | |
514 | if (TREE_CODE(decl) != VAR_DECL) |
515 | return; |
516 | |
517 | if (TREE_CODE(type) != RECORD_TYPE && TREE_CODE(type) != UNION_TYPE) |
518 | return; |
519 | |
520 | if (!lookup_attribute("randomize_performed" , TYPE_ATTRIBUTES(type))) |
521 | return; |
522 | |
523 | DECL_SIZE(decl) = 0; |
524 | DECL_SIZE_UNIT(decl) = 0; |
525 | SET_DECL_ALIGN(decl, 0); |
526 | SET_DECL_MODE (decl, VOIDmode); |
527 | SET_DECL_RTL(decl, 0); |
528 | update_decl_size(decl); |
529 | layout_decl(decl, 0); |
530 | } |
531 | |
532 | static void finish_type(void *event_data, void *data) |
533 | { |
534 | tree type = (tree)event_data; |
535 | |
536 | if (type == NULL_TREE || type == error_mark_node) |
537 | return; |
538 | |
539 | if (TREE_CODE(type) != RECORD_TYPE) |
540 | return; |
541 | |
542 | if (TYPE_FIELDS(type) == NULL_TREE) |
543 | return; |
544 | |
545 | if (lookup_attribute("randomize_considered" , TYPE_ATTRIBUTES(type))) |
546 | return; |
547 | |
548 | #ifdef __DEBUG_PLUGIN |
549 | fprintf(stderr, "Calling randomize_type on %s\n" , ORIG_TYPE_NAME(type)); |
550 | #endif |
551 | #ifdef __DEBUG_VERBOSE |
552 | debug_tree(type); |
553 | #endif |
554 | randomize_type(type); |
555 | |
556 | return; |
557 | } |
558 | |
559 | static struct attribute_spec randomize_layout_attr = { }; |
560 | static struct attribute_spec no_randomize_layout_attr = { }; |
561 | static struct attribute_spec randomize_considered_attr = { }; |
562 | static struct attribute_spec randomize_performed_attr = { }; |
563 | |
564 | static void register_attributes(void *event_data, void *data) |
565 | { |
566 | randomize_layout_attr.name = "randomize_layout" ; |
567 | randomize_layout_attr.type_required = true; |
568 | randomize_layout_attr.handler = handle_randomize_layout_attr; |
569 | randomize_layout_attr.affects_type_identity = true; |
570 | |
571 | no_randomize_layout_attr.name = "no_randomize_layout" ; |
572 | no_randomize_layout_attr.type_required = true; |
573 | no_randomize_layout_attr.handler = handle_randomize_layout_attr; |
574 | no_randomize_layout_attr.affects_type_identity = true; |
575 | |
576 | randomize_considered_attr.name = "randomize_considered" ; |
577 | randomize_considered_attr.type_required = true; |
578 | randomize_considered_attr.handler = handle_randomize_considered_attr; |
579 | |
580 | randomize_performed_attr.name = "randomize_performed" ; |
581 | randomize_performed_attr.type_required = true; |
582 | randomize_performed_attr.handler = handle_randomize_performed_attr; |
583 | |
584 | register_attribute(&randomize_layout_attr); |
585 | register_attribute(&no_randomize_layout_attr); |
586 | register_attribute(&randomize_considered_attr); |
587 | register_attribute(&randomize_performed_attr); |
588 | } |
589 | |
590 | static void check_bad_casts_in_constructor(tree var, tree init) |
591 | { |
592 | unsigned HOST_WIDE_INT idx; |
593 | tree field, val; |
594 | tree field_type, val_type; |
595 | |
596 | FOR_EACH_CONSTRUCTOR_ELT(CONSTRUCTOR_ELTS(init), idx, field, val) { |
597 | if (TREE_CODE(val) == CONSTRUCTOR) { |
598 | check_bad_casts_in_constructor(var, val); |
599 | continue; |
600 | } |
601 | |
602 | /* pipacs' plugin creates franken-arrays that differ from those produced by |
603 | normal code which all have valid 'field' trees. work around this */ |
604 | if (field == NULL_TREE) |
605 | continue; |
606 | field_type = TREE_TYPE(field); |
607 | val_type = TREE_TYPE(val); |
608 | |
609 | if (TREE_CODE(field_type) != POINTER_TYPE || TREE_CODE(val_type) != POINTER_TYPE) |
610 | continue; |
611 | |
612 | if (field_type == val_type) |
613 | continue; |
614 | |
615 | field_type = TYPE_MAIN_VARIANT(strip_array_types(TYPE_MAIN_VARIANT(TREE_TYPE(field_type)))); |
616 | val_type = TYPE_MAIN_VARIANT(strip_array_types(TYPE_MAIN_VARIANT(TREE_TYPE(val_type)))); |
617 | |
618 | if (field_type == void_type_node) |
619 | continue; |
620 | if (field_type == val_type) |
621 | continue; |
622 | if (TREE_CODE(val_type) != RECORD_TYPE) |
623 | continue; |
624 | |
625 | if (!lookup_attribute("randomize_performed" , TYPE_ATTRIBUTES(val_type))) |
626 | continue; |
627 | MISMATCH(DECL_SOURCE_LOCATION(var), "constructor\n" , TYPE_MAIN_VARIANT(field_type), TYPE_MAIN_VARIANT(val_type)); |
628 | } |
629 | } |
630 | |
631 | /* derived from the constify plugin */ |
632 | static void check_global_variables(void *event_data, void *data) |
633 | { |
634 | struct varpool_node *node; |
635 | tree init; |
636 | |
637 | FOR_EACH_VARIABLE(node) { |
638 | tree var = NODE_DECL(node); |
639 | init = DECL_INITIAL(var); |
640 | if (init == NULL_TREE) |
641 | continue; |
642 | |
643 | if (TREE_CODE(init) != CONSTRUCTOR) |
644 | continue; |
645 | |
646 | check_bad_casts_in_constructor(var, init); |
647 | } |
648 | } |
649 | |
650 | static bool dominated_by_is_err(const_tree rhs, basic_block bb) |
651 | { |
652 | basic_block dom; |
653 | gimple dom_stmt; |
654 | gimple call_stmt; |
655 | const_tree dom_lhs; |
656 | const_tree poss_is_err_cond; |
657 | const_tree poss_is_err_func; |
658 | const_tree is_err_arg; |
659 | |
660 | dom = get_immediate_dominator(CDI_DOMINATORS, bb); |
661 | if (!dom) |
662 | return false; |
663 | |
664 | dom_stmt = last_stmt(dom); |
665 | if (!dom_stmt) |
666 | return false; |
667 | |
668 | if (gimple_code(dom_stmt) != GIMPLE_COND) |
669 | return false; |
670 | |
671 | if (gimple_cond_code(dom_stmt) != NE_EXPR) |
672 | return false; |
673 | |
674 | if (!integer_zerop(gimple_cond_rhs(dom_stmt))) |
675 | return false; |
676 | |
677 | poss_is_err_cond = gimple_cond_lhs(dom_stmt); |
678 | |
679 | if (TREE_CODE(poss_is_err_cond) != SSA_NAME) |
680 | return false; |
681 | |
682 | call_stmt = SSA_NAME_DEF_STMT(poss_is_err_cond); |
683 | |
684 | if (gimple_code(call_stmt) != GIMPLE_CALL) |
685 | return false; |
686 | |
687 | dom_lhs = gimple_get_lhs(call_stmt); |
688 | poss_is_err_func = gimple_call_fndecl(call_stmt); |
689 | if (!poss_is_err_func) |
690 | return false; |
691 | if (dom_lhs != poss_is_err_cond) |
692 | return false; |
693 | if (strcmp(DECL_NAME_POINTER(poss_is_err_func), "IS_ERR" )) |
694 | return false; |
695 | |
696 | is_err_arg = gimple_call_arg(call_stmt, 0); |
697 | if (!is_err_arg) |
698 | return false; |
699 | |
700 | if (is_err_arg != rhs) |
701 | return false; |
702 | |
703 | return true; |
704 | } |
705 | |
706 | static void handle_local_var_initializers(void) |
707 | { |
708 | tree var; |
709 | unsigned int i; |
710 | |
711 | FOR_EACH_LOCAL_DECL(cfun, i, var) { |
712 | tree init = DECL_INITIAL(var); |
713 | if (!init) |
714 | continue; |
715 | if (TREE_CODE(init) != CONSTRUCTOR) |
716 | continue; |
717 | check_bad_casts_in_constructor(var, init); |
718 | } |
719 | } |
720 | |
721 | /* |
722 | * iterate over all statements to find "bad" casts: |
723 | * those where the address of the start of a structure is cast |
724 | * to a pointer of a structure of a different type, or a |
725 | * structure pointer type is cast to a different structure pointer type |
726 | */ |
727 | static unsigned int find_bad_casts_execute(void) |
728 | { |
729 | basic_block bb; |
730 | |
731 | handle_local_var_initializers(); |
732 | |
733 | FOR_EACH_BB_FN(bb, cfun) { |
734 | gimple_stmt_iterator gsi; |
735 | |
736 | for (gsi = gsi_start_bb(bb); !gsi_end_p(gsi); gsi_next(&gsi)) { |
737 | gimple stmt; |
738 | const_tree lhs; |
739 | const_tree lhs_type; |
740 | const_tree rhs1; |
741 | const_tree rhs_type; |
742 | const_tree ptr_lhs_type; |
743 | const_tree ptr_rhs_type; |
744 | const_tree op0; |
745 | const_tree op0_type; |
746 | enum tree_code rhs_code; |
747 | |
748 | stmt = gsi_stmt(gsi); |
749 | |
750 | #ifdef __DEBUG_PLUGIN |
751 | #ifdef __DEBUG_VERBOSE |
752 | debug_gimple_stmt(stmt); |
753 | debug_tree(gimple_get_lhs(stmt)); |
754 | #endif |
755 | #endif |
756 | |
757 | if (gimple_code(stmt) != GIMPLE_ASSIGN) |
758 | continue; |
759 | |
760 | #ifdef __DEBUG_PLUGIN |
761 | #ifdef __DEBUG_VERBOSE |
762 | debug_tree(gimple_assign_rhs1(stmt)); |
763 | #endif |
764 | #endif |
765 | |
766 | |
767 | rhs_code = gimple_assign_rhs_code(stmt); |
768 | |
769 | if (rhs_code != ADDR_EXPR && rhs_code != SSA_NAME) |
770 | continue; |
771 | |
772 | lhs = gimple_get_lhs(stmt); |
773 | lhs_type = TREE_TYPE(lhs); |
774 | rhs1 = gimple_assign_rhs1(stmt); |
775 | rhs_type = TREE_TYPE(rhs1); |
776 | |
777 | if (TREE_CODE(rhs_type) != POINTER_TYPE || |
778 | TREE_CODE(lhs_type) != POINTER_TYPE) |
779 | continue; |
780 | |
781 | ptr_lhs_type = TYPE_MAIN_VARIANT(strip_array_types(TYPE_MAIN_VARIANT(TREE_TYPE(lhs_type)))); |
782 | ptr_rhs_type = TYPE_MAIN_VARIANT(strip_array_types(TYPE_MAIN_VARIANT(TREE_TYPE(rhs_type)))); |
783 | |
784 | if (ptr_rhs_type == void_type_node) |
785 | continue; |
786 | |
787 | if (ptr_lhs_type == void_type_node) |
788 | continue; |
789 | |
790 | if (dominated_by_is_err(rhs1, bb)) |
791 | continue; |
792 | |
793 | if (TREE_CODE(ptr_rhs_type) != RECORD_TYPE) { |
794 | #ifndef __DEBUG_PLUGIN |
795 | if (lookup_attribute("randomize_performed" , TYPE_ATTRIBUTES(ptr_lhs_type))) |
796 | #endif |
797 | MISMATCH(gimple_location(stmt), "rhs" , ptr_lhs_type, ptr_rhs_type); |
798 | continue; |
799 | } |
800 | |
801 | if (rhs_code == SSA_NAME && ptr_lhs_type == ptr_rhs_type) |
802 | continue; |
803 | |
804 | if (rhs_code == ADDR_EXPR) { |
805 | op0 = TREE_OPERAND(rhs1, 0); |
806 | |
807 | if (op0 == NULL_TREE) |
808 | continue; |
809 | |
810 | if (TREE_CODE(op0) != VAR_DECL) |
811 | continue; |
812 | |
813 | op0_type = TYPE_MAIN_VARIANT(strip_array_types(TYPE_MAIN_VARIANT(TREE_TYPE(op0)))); |
814 | if (op0_type == ptr_lhs_type) |
815 | continue; |
816 | |
817 | #ifndef __DEBUG_PLUGIN |
818 | if (lookup_attribute("randomize_performed" , TYPE_ATTRIBUTES(op0_type))) |
819 | #endif |
820 | MISMATCH(gimple_location(stmt), "op0" , ptr_lhs_type, op0_type); |
821 | } else { |
822 | const_tree ssa_name_var = SSA_NAME_VAR(rhs1); |
823 | /* skip bogus type casts introduced by container_of */ |
824 | if (ssa_name_var != NULL_TREE && DECL_NAME(ssa_name_var) && |
825 | !strcmp((const char *)DECL_NAME_POINTER(ssa_name_var), "__mptr" )) |
826 | continue; |
827 | #ifndef __DEBUG_PLUGIN |
828 | if (lookup_attribute("randomize_performed" , TYPE_ATTRIBUTES(ptr_rhs_type))) |
829 | #endif |
830 | MISMATCH(gimple_location(stmt), "ssa" , ptr_lhs_type, ptr_rhs_type); |
831 | } |
832 | |
833 | } |
834 | } |
835 | return 0; |
836 | } |
837 | |
838 | #define PASS_NAME find_bad_casts |
839 | #define NO_GATE |
840 | #define TODO_FLAGS_FINISH TODO_dump_func |
841 | #include "gcc-generate-gimple-pass.h" |
842 | |
843 | __visible int plugin_init(struct plugin_name_args *plugin_info, struct plugin_gcc_version *version) |
844 | { |
845 | int i; |
846 | const char * const plugin_name = plugin_info->base_name; |
847 | const int argc = plugin_info->argc; |
848 | const struct plugin_argument * const argv = plugin_info->argv; |
849 | bool enable = true; |
850 | int obtained_seed = 0; |
851 | struct register_pass_info find_bad_casts_pass_info; |
852 | |
853 | find_bad_casts_pass_info.pass = make_find_bad_casts_pass(); |
854 | find_bad_casts_pass_info.reference_pass_name = "ssa" ; |
855 | find_bad_casts_pass_info.ref_pass_instance_number = 1; |
856 | find_bad_casts_pass_info.pos_op = PASS_POS_INSERT_AFTER; |
857 | |
858 | if (!plugin_default_version_check(version, &gcc_version)) { |
859 | error(G_("incompatible gcc/plugin versions" )); |
860 | return 1; |
861 | } |
862 | |
863 | if (strncmp(lang_hooks.name, "GNU C" , 5) && !strncmp(lang_hooks.name, "GNU C+" , 6)) { |
864 | inform(UNKNOWN_LOCATION, G_("%s supports C only, not %s" ), plugin_name, lang_hooks.name); |
865 | enable = false; |
866 | } |
867 | |
868 | for (i = 0; i < argc; ++i) { |
869 | if (!strcmp(argv[i].key, "disable" )) { |
870 | enable = false; |
871 | continue; |
872 | } |
873 | if (!strcmp(argv[i].key, "performance-mode" )) { |
874 | performance_mode = 1; |
875 | continue; |
876 | } |
877 | error(G_("unknown option '-fplugin-arg-%s-%s'" ), plugin_name, argv[i].key); |
878 | } |
879 | |
880 | if (strlen(randstruct_seed) != 64) { |
881 | error(G_("invalid seed value supplied for %s plugin" ), plugin_name); |
882 | return 1; |
883 | } |
884 | obtained_seed = sscanf(randstruct_seed, "%016llx%016llx%016llx%016llx" , |
885 | &shuffle_seed[0], &shuffle_seed[1], &shuffle_seed[2], &shuffle_seed[3]); |
886 | if (obtained_seed != 4) { |
887 | error(G_("Invalid seed supplied for %s plugin" ), plugin_name); |
888 | return 1; |
889 | } |
890 | |
891 | register_callback(plugin_name, PLUGIN_INFO, NULL, &randomize_layout_plugin_info); |
892 | if (enable) { |
893 | register_callback(plugin_name, PLUGIN_ALL_IPA_PASSES_START, check_global_variables, NULL); |
894 | register_callback(plugin_name, PLUGIN_PASS_MANAGER_SETUP, NULL, &find_bad_casts_pass_info); |
895 | register_callback(plugin_name, PLUGIN_FINISH_TYPE, finish_type, NULL); |
896 | register_callback(plugin_name, PLUGIN_FINISH_DECL, randomize_layout_finish_decl, NULL); |
897 | } |
898 | register_callback(plugin_name, PLUGIN_ATTRIBUTES, register_attributes, NULL); |
899 | |
900 | return 0; |
901 | } |
902 | |