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 | const_tree elemtype; |
282 | const_tree elemsize; |
283 | |
284 | fieldtype = TREE_TYPE(field); |
285 | typesize = TYPE_SIZE(fieldtype); |
286 | |
287 | if (TREE_CODE(fieldtype) != ARRAY_TYPE) |
288 | return false; |
289 | |
290 | elemtype = TREE_TYPE(fieldtype); |
291 | elemsize = TYPE_SIZE(elemtype); |
292 | |
293 | /* size of type is represented in bits */ |
294 | |
295 | if (typesize == NULL_TREE && TYPE_DOMAIN(fieldtype) != NULL_TREE && |
296 | TYPE_MAX_VALUE(TYPE_DOMAIN(fieldtype)) == NULL_TREE) |
297 | return true; |
298 | |
299 | if (typesize != NULL_TREE && |
300 | (TREE_CONSTANT(typesize) && (!tree_to_uhwi(typesize) || |
301 | tree_to_uhwi(typesize) == tree_to_uhwi(elemsize)))) |
302 | return true; |
303 | |
304 | return false; |
305 | } |
306 | |
307 | static int relayout_struct(tree type) |
308 | { |
309 | unsigned long num_fields = (unsigned long)list_length(TYPE_FIELDS(type)); |
310 | unsigned long shuffle_length = num_fields; |
311 | tree field; |
312 | tree newtree[num_fields]; |
313 | unsigned long i; |
314 | tree list; |
315 | tree variant; |
316 | tree main_variant; |
317 | expanded_location xloc; |
318 | bool has_flexarray = false; |
319 | |
320 | if (TYPE_FIELDS(type) == NULL_TREE) |
321 | return 0; |
322 | |
323 | if (num_fields < 2) |
324 | return 0; |
325 | |
326 | gcc_assert(TREE_CODE(type) == RECORD_TYPE); |
327 | |
328 | gcc_assert(num_fields < INT_MAX); |
329 | |
330 | if (lookup_attribute("randomize_performed" , TYPE_ATTRIBUTES(type)) || |
331 | lookup_attribute("no_randomize_layout" , TYPE_ATTRIBUTES(TYPE_MAIN_VARIANT(type)))) |
332 | return 0; |
333 | |
334 | /* Workaround for 3rd-party VirtualBox source that we can't modify ourselves */ |
335 | if (!strcmp((const char *)ORIG_TYPE_NAME(type), "INTNETTRUNKFACTORY" ) || |
336 | !strcmp((const char *)ORIG_TYPE_NAME(type), "RAWPCIFACTORY" )) |
337 | return 0; |
338 | |
339 | /* throw out any structs in uapi */ |
340 | xloc = expand_location(DECL_SOURCE_LOCATION(TYPE_FIELDS(type))); |
341 | |
342 | if (strstr(xloc.file, "/uapi/" )) |
343 | error(G_("attempted to randomize userland API struct %s" ), ORIG_TYPE_NAME(type)); |
344 | |
345 | for (field = TYPE_FIELDS(type), i = 0; field; field = TREE_CHAIN(field), i++) { |
346 | gcc_assert(TREE_CODE(field) == FIELD_DECL); |
347 | newtree[i] = field; |
348 | } |
349 | |
350 | /* |
351 | * enforce that we don't randomize the layout of the last |
352 | * element of a struct if it's a 0 or 1-length array |
353 | * or a proper flexible array |
354 | */ |
355 | if (is_flexible_array(newtree[num_fields - 1])) { |
356 | has_flexarray = true; |
357 | shuffle_length--; |
358 | } |
359 | |
360 | shuffle(type, (tree *)newtree, shuffle_length); |
361 | |
362 | /* |
363 | * set up a bogus anonymous struct field designed to error out on unnamed struct initializers |
364 | * as gcc provides no other way to detect such code |
365 | */ |
366 | list = make_node(FIELD_DECL); |
367 | TREE_CHAIN(list) = newtree[0]; |
368 | TREE_TYPE(list) = void_type_node; |
369 | DECL_SIZE(list) = bitsize_zero_node; |
370 | DECL_NONADDRESSABLE_P(list) = 1; |
371 | DECL_FIELD_BIT_OFFSET(list) = bitsize_zero_node; |
372 | DECL_SIZE_UNIT(list) = size_zero_node; |
373 | DECL_FIELD_OFFSET(list) = size_zero_node; |
374 | DECL_CONTEXT(list) = type; |
375 | // to satisfy the constify plugin |
376 | TREE_READONLY(list) = 1; |
377 | |
378 | for (i = 0; i < num_fields - 1; i++) |
379 | TREE_CHAIN(newtree[i]) = newtree[i+1]; |
380 | TREE_CHAIN(newtree[num_fields - 1]) = NULL_TREE; |
381 | |
382 | main_variant = TYPE_MAIN_VARIANT(type); |
383 | for (variant = main_variant; variant; variant = TYPE_NEXT_VARIANT(variant)) { |
384 | TYPE_FIELDS(variant) = list; |
385 | TYPE_ATTRIBUTES(variant) = copy_list(TYPE_ATTRIBUTES(variant)); |
386 | TYPE_ATTRIBUTES(variant) = tree_cons(get_identifier("randomize_performed" ), NULL_TREE, TYPE_ATTRIBUTES(variant)); |
387 | TYPE_ATTRIBUTES(variant) = tree_cons(get_identifier("designated_init" ), NULL_TREE, TYPE_ATTRIBUTES(variant)); |
388 | if (has_flexarray) |
389 | TYPE_ATTRIBUTES(type) = tree_cons(get_identifier("has_flexarray" ), NULL_TREE, TYPE_ATTRIBUTES(type)); |
390 | } |
391 | |
392 | /* |
393 | * force a re-layout of the main variant |
394 | * the TYPE_SIZE for all variants will be recomputed |
395 | * by finalize_type_size() |
396 | */ |
397 | TYPE_SIZE(main_variant) = NULL_TREE; |
398 | layout_type(main_variant); |
399 | gcc_assert(TYPE_SIZE(main_variant) != NULL_TREE); |
400 | |
401 | return 1; |
402 | } |
403 | |
404 | /* from constify plugin */ |
405 | static const_tree get_field_type(const_tree field) |
406 | { |
407 | return strip_array_types(TREE_TYPE(field)); |
408 | } |
409 | |
410 | /* from constify plugin */ |
411 | static bool is_fptr(const_tree fieldtype) |
412 | { |
413 | if (TREE_CODE(fieldtype) != POINTER_TYPE) |
414 | return false; |
415 | |
416 | return TREE_CODE(TREE_TYPE(fieldtype)) == FUNCTION_TYPE; |
417 | } |
418 | |
419 | /* derived from constify plugin */ |
420 | static int is_pure_ops_struct(const_tree node) |
421 | { |
422 | const_tree field; |
423 | |
424 | gcc_assert(TREE_CODE(node) == RECORD_TYPE || TREE_CODE(node) == UNION_TYPE); |
425 | |
426 | for (field = TYPE_FIELDS(node); field; field = TREE_CHAIN(field)) { |
427 | const_tree fieldtype = get_field_type(field); |
428 | enum tree_code code = TREE_CODE(fieldtype); |
429 | |
430 | if (node == fieldtype) |
431 | continue; |
432 | |
433 | if (code == RECORD_TYPE || code == UNION_TYPE) { |
434 | if (!is_pure_ops_struct(fieldtype)) |
435 | return 0; |
436 | continue; |
437 | } |
438 | |
439 | if (!is_fptr(fieldtype)) |
440 | return 0; |
441 | } |
442 | |
443 | return 1; |
444 | } |
445 | |
446 | static void randomize_type(tree type) |
447 | { |
448 | tree variant; |
449 | |
450 | gcc_assert(TREE_CODE(type) == RECORD_TYPE); |
451 | |
452 | if (lookup_attribute("randomize_considered" , TYPE_ATTRIBUTES(type))) |
453 | return; |
454 | |
455 | if (lookup_attribute("randomize_layout" , TYPE_ATTRIBUTES(TYPE_MAIN_VARIANT(type))) || is_pure_ops_struct(type)) |
456 | relayout_struct(type); |
457 | |
458 | for (variant = TYPE_MAIN_VARIANT(type); variant; variant = TYPE_NEXT_VARIANT(variant)) { |
459 | TYPE_ATTRIBUTES(type) = copy_list(TYPE_ATTRIBUTES(type)); |
460 | TYPE_ATTRIBUTES(type) = tree_cons(get_identifier("randomize_considered" ), NULL_TREE, TYPE_ATTRIBUTES(type)); |
461 | } |
462 | #ifdef __DEBUG_PLUGIN |
463 | fprintf(stderr, "Marking randomize_considered on struct %s\n" , ORIG_TYPE_NAME(type)); |
464 | #ifdef __DEBUG_VERBOSE |
465 | debug_tree(type); |
466 | #endif |
467 | #endif |
468 | } |
469 | |
470 | static void update_decl_size(tree decl) |
471 | { |
472 | tree lastval, lastidx, field, init, type, flexsize; |
473 | unsigned HOST_WIDE_INT len; |
474 | |
475 | type = TREE_TYPE(decl); |
476 | |
477 | if (!lookup_attribute("has_flexarray" , TYPE_ATTRIBUTES(type))) |
478 | return; |
479 | |
480 | init = DECL_INITIAL(decl); |
481 | if (init == NULL_TREE || init == error_mark_node) |
482 | return; |
483 | |
484 | if (TREE_CODE(init) != CONSTRUCTOR) |
485 | return; |
486 | |
487 | len = CONSTRUCTOR_NELTS(init); |
488 | if (!len) |
489 | return; |
490 | |
491 | lastval = CONSTRUCTOR_ELT(init, CONSTRUCTOR_NELTS(init) - 1)->value; |
492 | lastidx = CONSTRUCTOR_ELT(init, CONSTRUCTOR_NELTS(init) - 1)->index; |
493 | |
494 | for (field = TYPE_FIELDS(TREE_TYPE(decl)); TREE_CHAIN(field); field = TREE_CHAIN(field)) |
495 | ; |
496 | |
497 | if (lastidx != field) |
498 | return; |
499 | |
500 | if (TREE_CODE(lastval) != STRING_CST) { |
501 | error("Only string constants are supported as initializers " |
502 | "for randomized structures with flexible arrays" ); |
503 | return; |
504 | } |
505 | |
506 | flexsize = bitsize_int(TREE_STRING_LENGTH(lastval) * |
507 | tree_to_uhwi(TYPE_SIZE(TREE_TYPE(TREE_TYPE(lastval))))); |
508 | |
509 | DECL_SIZE(decl) = size_binop(PLUS_EXPR, TYPE_SIZE(type), flexsize); |
510 | |
511 | return; |
512 | } |
513 | |
514 | |
515 | static void randomize_layout_finish_decl(void *event_data, void *data) |
516 | { |
517 | tree decl = (tree)event_data; |
518 | tree type; |
519 | |
520 | if (decl == NULL_TREE || decl == error_mark_node) |
521 | return; |
522 | |
523 | type = TREE_TYPE(decl); |
524 | |
525 | if (TREE_CODE(decl) != VAR_DECL) |
526 | return; |
527 | |
528 | if (TREE_CODE(type) != RECORD_TYPE && TREE_CODE(type) != UNION_TYPE) |
529 | return; |
530 | |
531 | if (!lookup_attribute("randomize_performed" , TYPE_ATTRIBUTES(type))) |
532 | return; |
533 | |
534 | DECL_SIZE(decl) = 0; |
535 | DECL_SIZE_UNIT(decl) = 0; |
536 | SET_DECL_ALIGN(decl, 0); |
537 | SET_DECL_MODE (decl, VOIDmode); |
538 | SET_DECL_RTL(decl, 0); |
539 | update_decl_size(decl); |
540 | layout_decl(decl, 0); |
541 | } |
542 | |
543 | static void finish_type(void *event_data, void *data) |
544 | { |
545 | tree type = (tree)event_data; |
546 | |
547 | if (type == NULL_TREE || type == error_mark_node) |
548 | return; |
549 | |
550 | if (TREE_CODE(type) != RECORD_TYPE) |
551 | return; |
552 | |
553 | if (TYPE_FIELDS(type) == NULL_TREE) |
554 | return; |
555 | |
556 | if (lookup_attribute("randomize_considered" , TYPE_ATTRIBUTES(type))) |
557 | return; |
558 | |
559 | #ifdef __DEBUG_PLUGIN |
560 | fprintf(stderr, "Calling randomize_type on %s\n" , ORIG_TYPE_NAME(type)); |
561 | #endif |
562 | #ifdef __DEBUG_VERBOSE |
563 | debug_tree(type); |
564 | #endif |
565 | randomize_type(type); |
566 | |
567 | return; |
568 | } |
569 | |
570 | static struct attribute_spec randomize_layout_attr = { }; |
571 | static struct attribute_spec no_randomize_layout_attr = { }; |
572 | static struct attribute_spec randomize_considered_attr = { }; |
573 | static struct attribute_spec randomize_performed_attr = { }; |
574 | |
575 | static void register_attributes(void *event_data, void *data) |
576 | { |
577 | randomize_layout_attr.name = "randomize_layout" ; |
578 | randomize_layout_attr.type_required = true; |
579 | randomize_layout_attr.handler = handle_randomize_layout_attr; |
580 | randomize_layout_attr.affects_type_identity = true; |
581 | |
582 | no_randomize_layout_attr.name = "no_randomize_layout" ; |
583 | no_randomize_layout_attr.type_required = true; |
584 | no_randomize_layout_attr.handler = handle_randomize_layout_attr; |
585 | no_randomize_layout_attr.affects_type_identity = true; |
586 | |
587 | randomize_considered_attr.name = "randomize_considered" ; |
588 | randomize_considered_attr.type_required = true; |
589 | randomize_considered_attr.handler = handle_randomize_considered_attr; |
590 | |
591 | randomize_performed_attr.name = "randomize_performed" ; |
592 | randomize_performed_attr.type_required = true; |
593 | randomize_performed_attr.handler = handle_randomize_performed_attr; |
594 | |
595 | register_attribute(&randomize_layout_attr); |
596 | register_attribute(&no_randomize_layout_attr); |
597 | register_attribute(&randomize_considered_attr); |
598 | register_attribute(&randomize_performed_attr); |
599 | } |
600 | |
601 | static void check_bad_casts_in_constructor(tree var, tree init) |
602 | { |
603 | unsigned HOST_WIDE_INT idx; |
604 | tree field, val; |
605 | tree field_type, val_type; |
606 | |
607 | FOR_EACH_CONSTRUCTOR_ELT(CONSTRUCTOR_ELTS(init), idx, field, val) { |
608 | if (TREE_CODE(val) == CONSTRUCTOR) { |
609 | check_bad_casts_in_constructor(var, val); |
610 | continue; |
611 | } |
612 | |
613 | /* pipacs' plugin creates franken-arrays that differ from those produced by |
614 | normal code which all have valid 'field' trees. work around this */ |
615 | if (field == NULL_TREE) |
616 | continue; |
617 | field_type = TREE_TYPE(field); |
618 | val_type = TREE_TYPE(val); |
619 | |
620 | if (TREE_CODE(field_type) != POINTER_TYPE || TREE_CODE(val_type) != POINTER_TYPE) |
621 | continue; |
622 | |
623 | if (field_type == val_type) |
624 | continue; |
625 | |
626 | field_type = TYPE_MAIN_VARIANT(strip_array_types(TYPE_MAIN_VARIANT(TREE_TYPE(field_type)))); |
627 | val_type = TYPE_MAIN_VARIANT(strip_array_types(TYPE_MAIN_VARIANT(TREE_TYPE(val_type)))); |
628 | |
629 | if (field_type == void_type_node) |
630 | continue; |
631 | if (field_type == val_type) |
632 | continue; |
633 | if (TREE_CODE(val_type) != RECORD_TYPE) |
634 | continue; |
635 | |
636 | if (!lookup_attribute("randomize_performed" , TYPE_ATTRIBUTES(val_type))) |
637 | continue; |
638 | MISMATCH(DECL_SOURCE_LOCATION(var), "constructor\n" , TYPE_MAIN_VARIANT(field_type), TYPE_MAIN_VARIANT(val_type)); |
639 | } |
640 | } |
641 | |
642 | /* derived from the constify plugin */ |
643 | static void check_global_variables(void *event_data, void *data) |
644 | { |
645 | struct varpool_node *node; |
646 | tree init; |
647 | |
648 | FOR_EACH_VARIABLE(node) { |
649 | tree var = NODE_DECL(node); |
650 | init = DECL_INITIAL(var); |
651 | if (init == NULL_TREE) |
652 | continue; |
653 | |
654 | if (TREE_CODE(init) != CONSTRUCTOR) |
655 | continue; |
656 | |
657 | check_bad_casts_in_constructor(var, init); |
658 | } |
659 | } |
660 | |
661 | static bool dominated_by_is_err(const_tree rhs, basic_block bb) |
662 | { |
663 | basic_block dom; |
664 | gimple dom_stmt; |
665 | gimple call_stmt; |
666 | const_tree dom_lhs; |
667 | const_tree poss_is_err_cond; |
668 | const_tree poss_is_err_func; |
669 | const_tree is_err_arg; |
670 | |
671 | dom = get_immediate_dominator(CDI_DOMINATORS, bb); |
672 | if (!dom) |
673 | return false; |
674 | |
675 | dom_stmt = last_stmt(dom); |
676 | if (!dom_stmt) |
677 | return false; |
678 | |
679 | if (gimple_code(dom_stmt) != GIMPLE_COND) |
680 | return false; |
681 | |
682 | if (gimple_cond_code(dom_stmt) != NE_EXPR) |
683 | return false; |
684 | |
685 | if (!integer_zerop(gimple_cond_rhs(dom_stmt))) |
686 | return false; |
687 | |
688 | poss_is_err_cond = gimple_cond_lhs(dom_stmt); |
689 | |
690 | if (TREE_CODE(poss_is_err_cond) != SSA_NAME) |
691 | return false; |
692 | |
693 | call_stmt = SSA_NAME_DEF_STMT(poss_is_err_cond); |
694 | |
695 | if (gimple_code(call_stmt) != GIMPLE_CALL) |
696 | return false; |
697 | |
698 | dom_lhs = gimple_get_lhs(call_stmt); |
699 | poss_is_err_func = gimple_call_fndecl(call_stmt); |
700 | if (!poss_is_err_func) |
701 | return false; |
702 | if (dom_lhs != poss_is_err_cond) |
703 | return false; |
704 | if (strcmp(DECL_NAME_POINTER(poss_is_err_func), "IS_ERR" )) |
705 | return false; |
706 | |
707 | is_err_arg = gimple_call_arg(call_stmt, 0); |
708 | if (!is_err_arg) |
709 | return false; |
710 | |
711 | if (is_err_arg != rhs) |
712 | return false; |
713 | |
714 | return true; |
715 | } |
716 | |
717 | static void handle_local_var_initializers(void) |
718 | { |
719 | tree var; |
720 | unsigned int i; |
721 | |
722 | FOR_EACH_LOCAL_DECL(cfun, i, var) { |
723 | tree init = DECL_INITIAL(var); |
724 | if (!init) |
725 | continue; |
726 | if (TREE_CODE(init) != CONSTRUCTOR) |
727 | continue; |
728 | check_bad_casts_in_constructor(var, init); |
729 | } |
730 | } |
731 | |
732 | /* |
733 | * iterate over all statements to find "bad" casts: |
734 | * those where the address of the start of a structure is cast |
735 | * to a pointer of a structure of a different type, or a |
736 | * structure pointer type is cast to a different structure pointer type |
737 | */ |
738 | static unsigned int find_bad_casts_execute(void) |
739 | { |
740 | basic_block bb; |
741 | |
742 | handle_local_var_initializers(); |
743 | |
744 | FOR_EACH_BB_FN(bb, cfun) { |
745 | gimple_stmt_iterator gsi; |
746 | |
747 | for (gsi = gsi_start_bb(bb); !gsi_end_p(gsi); gsi_next(&gsi)) { |
748 | gimple stmt; |
749 | const_tree lhs; |
750 | const_tree lhs_type; |
751 | const_tree rhs1; |
752 | const_tree rhs_type; |
753 | const_tree ptr_lhs_type; |
754 | const_tree ptr_rhs_type; |
755 | const_tree op0; |
756 | const_tree op0_type; |
757 | enum tree_code rhs_code; |
758 | |
759 | stmt = gsi_stmt(gsi); |
760 | |
761 | #ifdef __DEBUG_PLUGIN |
762 | #ifdef __DEBUG_VERBOSE |
763 | debug_gimple_stmt(stmt); |
764 | debug_tree(gimple_get_lhs(stmt)); |
765 | #endif |
766 | #endif |
767 | |
768 | if (gimple_code(stmt) != GIMPLE_ASSIGN) |
769 | continue; |
770 | |
771 | #ifdef __DEBUG_PLUGIN |
772 | #ifdef __DEBUG_VERBOSE |
773 | debug_tree(gimple_assign_rhs1(stmt)); |
774 | #endif |
775 | #endif |
776 | |
777 | |
778 | rhs_code = gimple_assign_rhs_code(stmt); |
779 | |
780 | if (rhs_code != ADDR_EXPR && rhs_code != SSA_NAME) |
781 | continue; |
782 | |
783 | lhs = gimple_get_lhs(stmt); |
784 | lhs_type = TREE_TYPE(lhs); |
785 | rhs1 = gimple_assign_rhs1(stmt); |
786 | rhs_type = TREE_TYPE(rhs1); |
787 | |
788 | if (TREE_CODE(rhs_type) != POINTER_TYPE || |
789 | TREE_CODE(lhs_type) != POINTER_TYPE) |
790 | continue; |
791 | |
792 | ptr_lhs_type = TYPE_MAIN_VARIANT(strip_array_types(TYPE_MAIN_VARIANT(TREE_TYPE(lhs_type)))); |
793 | ptr_rhs_type = TYPE_MAIN_VARIANT(strip_array_types(TYPE_MAIN_VARIANT(TREE_TYPE(rhs_type)))); |
794 | |
795 | if (ptr_rhs_type == void_type_node) |
796 | continue; |
797 | |
798 | if (ptr_lhs_type == void_type_node) |
799 | continue; |
800 | |
801 | if (dominated_by_is_err(rhs1, bb)) |
802 | continue; |
803 | |
804 | if (TREE_CODE(ptr_rhs_type) != RECORD_TYPE) { |
805 | #ifndef __DEBUG_PLUGIN |
806 | if (lookup_attribute("randomize_performed" , TYPE_ATTRIBUTES(ptr_lhs_type))) |
807 | #endif |
808 | MISMATCH(gimple_location(stmt), "rhs" , ptr_lhs_type, ptr_rhs_type); |
809 | continue; |
810 | } |
811 | |
812 | if (rhs_code == SSA_NAME && ptr_lhs_type == ptr_rhs_type) |
813 | continue; |
814 | |
815 | if (rhs_code == ADDR_EXPR) { |
816 | op0 = TREE_OPERAND(rhs1, 0); |
817 | |
818 | if (op0 == NULL_TREE) |
819 | continue; |
820 | |
821 | if (TREE_CODE(op0) != VAR_DECL) |
822 | continue; |
823 | |
824 | op0_type = TYPE_MAIN_VARIANT(strip_array_types(TYPE_MAIN_VARIANT(TREE_TYPE(op0)))); |
825 | if (op0_type == ptr_lhs_type) |
826 | continue; |
827 | |
828 | #ifndef __DEBUG_PLUGIN |
829 | if (lookup_attribute("randomize_performed" , TYPE_ATTRIBUTES(op0_type))) |
830 | #endif |
831 | MISMATCH(gimple_location(stmt), "op0" , ptr_lhs_type, op0_type); |
832 | } else { |
833 | const_tree ssa_name_var = SSA_NAME_VAR(rhs1); |
834 | /* skip bogus type casts introduced by container_of */ |
835 | if (ssa_name_var != NULL_TREE && DECL_NAME(ssa_name_var) && |
836 | !strcmp((const char *)DECL_NAME_POINTER(ssa_name_var), "__mptr" )) |
837 | continue; |
838 | #ifndef __DEBUG_PLUGIN |
839 | if (lookup_attribute("randomize_performed" , TYPE_ATTRIBUTES(ptr_rhs_type))) |
840 | #endif |
841 | MISMATCH(gimple_location(stmt), "ssa" , ptr_lhs_type, ptr_rhs_type); |
842 | } |
843 | |
844 | } |
845 | } |
846 | return 0; |
847 | } |
848 | |
849 | #define PASS_NAME find_bad_casts |
850 | #define NO_GATE |
851 | #define TODO_FLAGS_FINISH TODO_dump_func |
852 | #include "gcc-generate-gimple-pass.h" |
853 | |
854 | __visible int plugin_init(struct plugin_name_args *plugin_info, struct plugin_gcc_version *version) |
855 | { |
856 | int i; |
857 | const char * const plugin_name = plugin_info->base_name; |
858 | const int argc = plugin_info->argc; |
859 | const struct plugin_argument * const argv = plugin_info->argv; |
860 | bool enable = true; |
861 | int obtained_seed = 0; |
862 | struct register_pass_info find_bad_casts_pass_info; |
863 | |
864 | find_bad_casts_pass_info.pass = make_find_bad_casts_pass(); |
865 | find_bad_casts_pass_info.reference_pass_name = "ssa" ; |
866 | find_bad_casts_pass_info.ref_pass_instance_number = 1; |
867 | find_bad_casts_pass_info.pos_op = PASS_POS_INSERT_AFTER; |
868 | |
869 | if (!plugin_default_version_check(version, &gcc_version)) { |
870 | error(G_("incompatible gcc/plugin versions" )); |
871 | return 1; |
872 | } |
873 | |
874 | if (strncmp(lang_hooks.name, "GNU C" , 5) && !strncmp(lang_hooks.name, "GNU C+" , 6)) { |
875 | inform(UNKNOWN_LOCATION, G_("%s supports C only, not %s" ), plugin_name, lang_hooks.name); |
876 | enable = false; |
877 | } |
878 | |
879 | for (i = 0; i < argc; ++i) { |
880 | if (!strcmp(argv[i].key, "disable" )) { |
881 | enable = false; |
882 | continue; |
883 | } |
884 | if (!strcmp(argv[i].key, "performance-mode" )) { |
885 | performance_mode = 1; |
886 | continue; |
887 | } |
888 | error(G_("unknown option '-fplugin-arg-%s-%s'" ), plugin_name, argv[i].key); |
889 | } |
890 | |
891 | if (strlen(randstruct_seed) != 64) { |
892 | error(G_("invalid seed value supplied for %s plugin" ), plugin_name); |
893 | return 1; |
894 | } |
895 | obtained_seed = sscanf(randstruct_seed, "%016llx%016llx%016llx%016llx" , |
896 | &shuffle_seed[0], &shuffle_seed[1], &shuffle_seed[2], &shuffle_seed[3]); |
897 | if (obtained_seed != 4) { |
898 | error(G_("Invalid seed supplied for %s plugin" ), plugin_name); |
899 | return 1; |
900 | } |
901 | |
902 | register_callback(plugin_name, PLUGIN_INFO, NULL, &randomize_layout_plugin_info); |
903 | if (enable) { |
904 | register_callback(plugin_name, PLUGIN_ALL_IPA_PASSES_START, check_global_variables, NULL); |
905 | register_callback(plugin_name, PLUGIN_PASS_MANAGER_SETUP, NULL, &find_bad_casts_pass_info); |
906 | register_callback(plugin_name, PLUGIN_FINISH_TYPE, finish_type, NULL); |
907 | register_callback(plugin_name, PLUGIN_FINISH_DECL, randomize_layout_finish_decl, NULL); |
908 | } |
909 | register_callback(plugin_name, PLUGIN_ATTRIBUTES, register_attributes, NULL); |
910 | |
911 | return 0; |
912 | } |
913 | |