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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 | ||
34 | static int performance_mode; | |
35 | ||
36 | static 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 | ||
42 | struct whitelist_entry { | |
43 | const char *pathname; | |
44 | const char *lhs; | |
45 | const char *rhs; | |
46 | }; | |
47 | ||
48 | static 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 *" }, | |
fd466e06 KC |
55 | /* walk struct security_hook_heads as an array of struct list_head */ |
56 | { "security/security.c", "list_head", "security_hook_heads" }, | |
313dd1b6 KC |
57 | { } |
58 | }; | |
59 | ||
60 | /* from old Linux dcache.h */ | |
61 | static inline unsigned long | |
62 | partial_name_hash(unsigned long c, unsigned long prevhash) | |
63 | { | |
64 | return (prevhash + (c << 4) + (c >> 4)) * 11; | |
65 | } | |
66 | static inline unsigned int | |
67 | name_hash(const unsigned char *name) | |
68 | { | |
69 | unsigned long hash = 0; | |
70 | unsigned int len = strlen((const char *)name); | |
71 | while (len--) | |
72 | hash = partial_name_hash(*name++, hash); | |
73 | return (unsigned int)hash; | |
74 | } | |
75 | ||
76 | static tree handle_randomize_layout_attr(tree *node, tree name, tree args, int flags, bool *no_add_attrs) | |
77 | { | |
78 | tree type; | |
79 | ||
80 | *no_add_attrs = true; | |
81 | if (TREE_CODE(*node) == FUNCTION_DECL) { | |
82 | error("%qE attribute does not apply to functions (%qF)", name, *node); | |
83 | return NULL_TREE; | |
84 | } | |
85 | ||
86 | if (TREE_CODE(*node) == PARM_DECL) { | |
87 | error("%qE attribute does not apply to function parameters (%qD)", name, *node); | |
88 | return NULL_TREE; | |
89 | } | |
90 | ||
91 | if (TREE_CODE(*node) == VAR_DECL) { | |
92 | error("%qE attribute does not apply to variables (%qD)", name, *node); | |
93 | return NULL_TREE; | |
94 | } | |
95 | ||
96 | if (TYPE_P(*node)) { | |
97 | type = *node; | |
98 | } else { | |
99 | gcc_assert(TREE_CODE(*node) == TYPE_DECL); | |
100 | type = TREE_TYPE(*node); | |
101 | } | |
102 | ||
103 | if (TREE_CODE(type) != RECORD_TYPE) { | |
104 | error("%qE attribute used on %qT applies to struct types only", name, type); | |
105 | return NULL_TREE; | |
106 | } | |
107 | ||
108 | if (lookup_attribute(IDENTIFIER_POINTER(name), TYPE_ATTRIBUTES(type))) { | |
109 | error("%qE attribute is already applied to the type %qT", name, type); | |
110 | return NULL_TREE; | |
111 | } | |
112 | ||
113 | *no_add_attrs = false; | |
114 | ||
115 | return NULL_TREE; | |
116 | } | |
117 | ||
118 | /* set on complete types that we don't need to inspect further at all */ | |
119 | static tree handle_randomize_considered_attr(tree *node, tree name, tree args, int flags, bool *no_add_attrs) | |
120 | { | |
121 | *no_add_attrs = false; | |
122 | return NULL_TREE; | |
123 | } | |
124 | ||
125 | /* | |
126 | * set on types that we've performed a shuffle on, to prevent re-shuffling | |
127 | * this does not preclude us from inspecting its fields for potential shuffles | |
128 | */ | |
129 | static tree handle_randomize_performed_attr(tree *node, tree name, tree args, int flags, bool *no_add_attrs) | |
130 | { | |
131 | *no_add_attrs = false; | |
132 | return NULL_TREE; | |
133 | } | |
134 | ||
135 | /* | |
136 | * 64bit variant of Bob Jenkins' public domain PRNG | |
137 | * 256 bits of internal state | |
138 | */ | |
139 | ||
140 | typedef unsigned long long u64; | |
141 | ||
142 | typedef struct ranctx { u64 a; u64 b; u64 c; u64 d; } ranctx; | |
143 | ||
144 | #define rot(x,k) (((x)<<(k))|((x)>>(64-(k)))) | |
145 | static u64 ranval(ranctx *x) { | |
146 | u64 e = x->a - rot(x->b, 7); | |
147 | x->a = x->b ^ rot(x->c, 13); | |
148 | x->b = x->c + rot(x->d, 37); | |
149 | x->c = x->d + e; | |
150 | x->d = e + x->a; | |
151 | return x->d; | |
152 | } | |
153 | ||
154 | static void raninit(ranctx *x, u64 *seed) { | |
155 | int i; | |
156 | ||
157 | x->a = seed[0]; | |
158 | x->b = seed[1]; | |
159 | x->c = seed[2]; | |
160 | x->d = seed[3]; | |
161 | ||
162 | for (i=0; i < 30; ++i) | |
163 | (void)ranval(x); | |
164 | } | |
165 | ||
166 | static u64 shuffle_seed[4]; | |
167 | ||
168 | struct partition_group { | |
169 | tree tree_start; | |
170 | unsigned long start; | |
171 | unsigned long length; | |
172 | }; | |
173 | ||
174 | static void partition_struct(tree *fields, unsigned long length, struct partition_group *size_groups, unsigned long *num_groups) | |
175 | { | |
176 | unsigned long i; | |
177 | unsigned long accum_size = 0; | |
178 | unsigned long accum_length = 0; | |
179 | unsigned long group_idx = 0; | |
180 | ||
181 | gcc_assert(length < INT_MAX); | |
182 | ||
183 | memset(size_groups, 0, sizeof(struct partition_group) * length); | |
184 | ||
185 | for (i = 0; i < length; i++) { | |
186 | if (size_groups[group_idx].tree_start == NULL_TREE) { | |
187 | size_groups[group_idx].tree_start = fields[i]; | |
188 | size_groups[group_idx].start = i; | |
189 | accum_length = 0; | |
190 | accum_size = 0; | |
191 | } | |
192 | accum_size += (unsigned long)int_size_in_bytes(TREE_TYPE(fields[i])); | |
193 | accum_length++; | |
194 | if (accum_size >= 64) { | |
195 | size_groups[group_idx].length = accum_length; | |
196 | accum_length = 0; | |
197 | group_idx++; | |
198 | } | |
199 | } | |
200 | ||
201 | if (size_groups[group_idx].tree_start != NULL_TREE && | |
202 | !size_groups[group_idx].length) { | |
203 | size_groups[group_idx].length = accum_length; | |
204 | group_idx++; | |
205 | } | |
206 | ||
207 | *num_groups = group_idx; | |
208 | } | |
209 | ||
210 | static void performance_shuffle(tree *newtree, unsigned long length, ranctx *prng_state) | |
211 | { | |
212 | unsigned long i, x; | |
213 | struct partition_group size_group[length]; | |
214 | unsigned long num_groups = 0; | |
215 | unsigned long randnum; | |
216 | ||
217 | partition_struct(newtree, length, (struct partition_group *)&size_group, &num_groups); | |
218 | for (i = num_groups - 1; i > 0; i--) { | |
219 | struct partition_group tmp; | |
220 | randnum = ranval(prng_state) % (i + 1); | |
221 | tmp = size_group[i]; | |
222 | size_group[i] = size_group[randnum]; | |
223 | size_group[randnum] = tmp; | |
224 | } | |
225 | ||
226 | for (x = 0; x < num_groups; x++) { | |
227 | for (i = size_group[x].start + size_group[x].length - 1; i > size_group[x].start; i--) { | |
228 | tree tmp; | |
229 | if (DECL_BIT_FIELD_TYPE(newtree[i])) | |
230 | continue; | |
231 | randnum = ranval(prng_state) % (i + 1); | |
232 | // we could handle this case differently if desired | |
233 | if (DECL_BIT_FIELD_TYPE(newtree[randnum])) | |
234 | continue; | |
235 | tmp = newtree[i]; | |
236 | newtree[i] = newtree[randnum]; | |
237 | newtree[randnum] = tmp; | |
238 | } | |
239 | } | |
240 | } | |
241 | ||
242 | static void full_shuffle(tree *newtree, unsigned long length, ranctx *prng_state) | |
243 | { | |
244 | unsigned long i, randnum; | |
245 | ||
246 | for (i = length - 1; i > 0; i--) { | |
247 | tree tmp; | |
248 | randnum = ranval(prng_state) % (i + 1); | |
249 | tmp = newtree[i]; | |
250 | newtree[i] = newtree[randnum]; | |
251 | newtree[randnum] = tmp; | |
252 | } | |
253 | } | |
254 | ||
255 | /* modern in-place Fisher-Yates shuffle */ | |
256 | static void shuffle(const_tree type, tree *newtree, unsigned long length) | |
257 | { | |
258 | unsigned long i; | |
259 | u64 seed[4]; | |
260 | ranctx prng_state; | |
261 | const unsigned char *structname; | |
262 | ||
263 | if (length == 0) | |
264 | return; | |
265 | ||
266 | gcc_assert(TREE_CODE(type) == RECORD_TYPE); | |
267 | ||
268 | structname = ORIG_TYPE_NAME(type); | |
269 | ||
270 | #ifdef __DEBUG_PLUGIN | |
271 | fprintf(stderr, "Shuffling struct %s %p\n", (const char *)structname, type); | |
272 | #ifdef __DEBUG_VERBOSE | |
273 | debug_tree((tree)type); | |
274 | #endif | |
275 | #endif | |
276 | ||
277 | for (i = 0; i < 4; i++) { | |
278 | seed[i] = shuffle_seed[i]; | |
279 | seed[i] ^= name_hash(structname); | |
280 | } | |
281 | ||
282 | raninit(&prng_state, (u64 *)&seed); | |
283 | ||
284 | if (performance_mode) | |
285 | performance_shuffle(newtree, length, &prng_state); | |
286 | else | |
287 | full_shuffle(newtree, length, &prng_state); | |
288 | } | |
289 | ||
290 | static bool is_flexible_array(const_tree field) | |
291 | { | |
292 | const_tree fieldtype; | |
293 | const_tree typesize; | |
294 | const_tree elemtype; | |
295 | const_tree elemsize; | |
296 | ||
297 | fieldtype = TREE_TYPE(field); | |
298 | typesize = TYPE_SIZE(fieldtype); | |
299 | ||
300 | if (TREE_CODE(fieldtype) != ARRAY_TYPE) | |
301 | return false; | |
302 | ||
303 | elemtype = TREE_TYPE(fieldtype); | |
304 | elemsize = TYPE_SIZE(elemtype); | |
305 | ||
306 | /* size of type is represented in bits */ | |
307 | ||
308 | if (typesize == NULL_TREE && TYPE_DOMAIN(fieldtype) != NULL_TREE && | |
309 | TYPE_MAX_VALUE(TYPE_DOMAIN(fieldtype)) == NULL_TREE) | |
310 | return true; | |
311 | ||
312 | if (typesize != NULL_TREE && | |
313 | (TREE_CONSTANT(typesize) && (!tree_to_uhwi(typesize) || | |
314 | tree_to_uhwi(typesize) == tree_to_uhwi(elemsize)))) | |
315 | return true; | |
316 | ||
317 | return false; | |
318 | } | |
319 | ||
320 | static int relayout_struct(tree type) | |
321 | { | |
322 | unsigned long num_fields = (unsigned long)list_length(TYPE_FIELDS(type)); | |
323 | unsigned long shuffle_length = num_fields; | |
324 | tree field; | |
325 | tree newtree[num_fields]; | |
326 | unsigned long i; | |
327 | tree list; | |
328 | tree variant; | |
329 | tree main_variant; | |
330 | expanded_location xloc; | |
331 | bool has_flexarray = false; | |
332 | ||
333 | if (TYPE_FIELDS(type) == NULL_TREE) | |
334 | return 0; | |
335 | ||
336 | if (num_fields < 2) | |
337 | return 0; | |
338 | ||
339 | gcc_assert(TREE_CODE(type) == RECORD_TYPE); | |
340 | ||
341 | gcc_assert(num_fields < INT_MAX); | |
342 | ||
343 | if (lookup_attribute("randomize_performed", TYPE_ATTRIBUTES(type)) || | |
344 | lookup_attribute("no_randomize_layout", TYPE_ATTRIBUTES(TYPE_MAIN_VARIANT(type)))) | |
345 | return 0; | |
346 | ||
347 | /* Workaround for 3rd-party VirtualBox source that we can't modify ourselves */ | |
348 | if (!strcmp((const char *)ORIG_TYPE_NAME(type), "INTNETTRUNKFACTORY") || | |
349 | !strcmp((const char *)ORIG_TYPE_NAME(type), "RAWPCIFACTORY")) | |
350 | return 0; | |
351 | ||
352 | /* throw out any structs in uapi */ | |
353 | xloc = expand_location(DECL_SOURCE_LOCATION(TYPE_FIELDS(type))); | |
354 | ||
355 | if (strstr(xloc.file, "/uapi/")) | |
356 | error(G_("attempted to randomize userland API struct %s"), ORIG_TYPE_NAME(type)); | |
357 | ||
358 | for (field = TYPE_FIELDS(type), i = 0; field; field = TREE_CHAIN(field), i++) { | |
359 | gcc_assert(TREE_CODE(field) == FIELD_DECL); | |
360 | newtree[i] = field; | |
361 | } | |
362 | ||
363 | /* | |
364 | * enforce that we don't randomize the layout of the last | |
365 | * element of a struct if it's a 0 or 1-length array | |
366 | * or a proper flexible array | |
367 | */ | |
368 | if (is_flexible_array(newtree[num_fields - 1])) { | |
369 | has_flexarray = true; | |
370 | shuffle_length--; | |
371 | } | |
372 | ||
373 | shuffle(type, (tree *)newtree, shuffle_length); | |
374 | ||
375 | /* | |
376 | * set up a bogus anonymous struct field designed to error out on unnamed struct initializers | |
377 | * as gcc provides no other way to detect such code | |
378 | */ | |
379 | list = make_node(FIELD_DECL); | |
380 | TREE_CHAIN(list) = newtree[0]; | |
381 | TREE_TYPE(list) = void_type_node; | |
382 | DECL_SIZE(list) = bitsize_zero_node; | |
383 | DECL_NONADDRESSABLE_P(list) = 1; | |
384 | DECL_FIELD_BIT_OFFSET(list) = bitsize_zero_node; | |
385 | DECL_SIZE_UNIT(list) = size_zero_node; | |
386 | DECL_FIELD_OFFSET(list) = size_zero_node; | |
387 | DECL_CONTEXT(list) = type; | |
388 | // to satisfy the constify plugin | |
389 | TREE_READONLY(list) = 1; | |
390 | ||
391 | for (i = 0; i < num_fields - 1; i++) | |
392 | TREE_CHAIN(newtree[i]) = newtree[i+1]; | |
393 | TREE_CHAIN(newtree[num_fields - 1]) = NULL_TREE; | |
394 | ||
395 | main_variant = TYPE_MAIN_VARIANT(type); | |
396 | for (variant = main_variant; variant; variant = TYPE_NEXT_VARIANT(variant)) { | |
397 | TYPE_FIELDS(variant) = list; | |
398 | TYPE_ATTRIBUTES(variant) = copy_list(TYPE_ATTRIBUTES(variant)); | |
399 | TYPE_ATTRIBUTES(variant) = tree_cons(get_identifier("randomize_performed"), NULL_TREE, TYPE_ATTRIBUTES(variant)); | |
400 | TYPE_ATTRIBUTES(variant) = tree_cons(get_identifier("designated_init"), NULL_TREE, TYPE_ATTRIBUTES(variant)); | |
401 | if (has_flexarray) | |
402 | TYPE_ATTRIBUTES(type) = tree_cons(get_identifier("has_flexarray"), NULL_TREE, TYPE_ATTRIBUTES(type)); | |
403 | } | |
404 | ||
405 | /* | |
406 | * force a re-layout of the main variant | |
407 | * the TYPE_SIZE for all variants will be recomputed | |
408 | * by finalize_type_size() | |
409 | */ | |
410 | TYPE_SIZE(main_variant) = NULL_TREE; | |
411 | layout_type(main_variant); | |
412 | gcc_assert(TYPE_SIZE(main_variant) != NULL_TREE); | |
413 | ||
414 | return 1; | |
415 | } | |
416 | ||
417 | /* from constify plugin */ | |
418 | static const_tree get_field_type(const_tree field) | |
419 | { | |
420 | return strip_array_types(TREE_TYPE(field)); | |
421 | } | |
422 | ||
423 | /* from constify plugin */ | |
424 | static bool is_fptr(const_tree fieldtype) | |
425 | { | |
426 | if (TREE_CODE(fieldtype) != POINTER_TYPE) | |
427 | return false; | |
428 | ||
429 | return TREE_CODE(TREE_TYPE(fieldtype)) == FUNCTION_TYPE; | |
430 | } | |
431 | ||
432 | /* derived from constify plugin */ | |
433 | static int is_pure_ops_struct(const_tree node) | |
434 | { | |
435 | const_tree field; | |
436 | ||
437 | gcc_assert(TREE_CODE(node) == RECORD_TYPE || TREE_CODE(node) == UNION_TYPE); | |
438 | ||
313dd1b6 KC |
439 | for (field = TYPE_FIELDS(node); field; field = TREE_CHAIN(field)) { |
440 | const_tree fieldtype = get_field_type(field); | |
441 | enum tree_code code = TREE_CODE(fieldtype); | |
442 | ||
443 | if (node == fieldtype) | |
444 | continue; | |
445 | ||
446 | if (!is_fptr(fieldtype)) | |
447 | return 0; | |
448 | ||
449 | if (code != RECORD_TYPE && code != UNION_TYPE) | |
450 | continue; | |
451 | ||
452 | if (!is_pure_ops_struct(fieldtype)) | |
453 | return 0; | |
454 | } | |
455 | ||
456 | return 1; | |
457 | } | |
458 | ||
459 | static void randomize_type(tree type) | |
460 | { | |
461 | tree variant; | |
462 | ||
463 | gcc_assert(TREE_CODE(type) == RECORD_TYPE); | |
464 | ||
465 | if (lookup_attribute("randomize_considered", TYPE_ATTRIBUTES(type))) | |
466 | return; | |
467 | ||
468 | if (lookup_attribute("randomize_layout", TYPE_ATTRIBUTES(TYPE_MAIN_VARIANT(type))) || is_pure_ops_struct(type)) | |
469 | relayout_struct(type); | |
470 | ||
471 | for (variant = TYPE_MAIN_VARIANT(type); variant; variant = TYPE_NEXT_VARIANT(variant)) { | |
472 | TYPE_ATTRIBUTES(type) = copy_list(TYPE_ATTRIBUTES(type)); | |
473 | TYPE_ATTRIBUTES(type) = tree_cons(get_identifier("randomize_considered"), NULL_TREE, TYPE_ATTRIBUTES(type)); | |
474 | } | |
475 | #ifdef __DEBUG_PLUGIN | |
476 | fprintf(stderr, "Marking randomize_considered on struct %s\n", ORIG_TYPE_NAME(type)); | |
477 | #ifdef __DEBUG_VERBOSE | |
478 | debug_tree(type); | |
479 | #endif | |
480 | #endif | |
481 | } | |
482 | ||
483 | static void update_decl_size(tree decl) | |
484 | { | |
485 | tree lastval, lastidx, field, init, type, flexsize; | |
486 | unsigned HOST_WIDE_INT len; | |
487 | ||
488 | type = TREE_TYPE(decl); | |
489 | ||
490 | if (!lookup_attribute("has_flexarray", TYPE_ATTRIBUTES(type))) | |
491 | return; | |
492 | ||
493 | init = DECL_INITIAL(decl); | |
494 | if (init == NULL_TREE || init == error_mark_node) | |
495 | return; | |
496 | ||
497 | if (TREE_CODE(init) != CONSTRUCTOR) | |
498 | return; | |
499 | ||
500 | len = CONSTRUCTOR_NELTS(init); | |
501 | if (!len) | |
502 | return; | |
503 | ||
504 | lastval = CONSTRUCTOR_ELT(init, CONSTRUCTOR_NELTS(init) - 1)->value; | |
505 | lastidx = CONSTRUCTOR_ELT(init, CONSTRUCTOR_NELTS(init) - 1)->index; | |
506 | ||
507 | for (field = TYPE_FIELDS(TREE_TYPE(decl)); TREE_CHAIN(field); field = TREE_CHAIN(field)) | |
508 | ; | |
509 | ||
510 | if (lastidx != field) | |
511 | return; | |
512 | ||
513 | if (TREE_CODE(lastval) != STRING_CST) { | |
514 | error("Only string constants are supported as initializers " | |
515 | "for randomized structures with flexible arrays"); | |
516 | return; | |
517 | } | |
518 | ||
519 | flexsize = bitsize_int(TREE_STRING_LENGTH(lastval) * | |
520 | tree_to_uhwi(TYPE_SIZE(TREE_TYPE(TREE_TYPE(lastval))))); | |
521 | ||
522 | DECL_SIZE(decl) = size_binop(PLUS_EXPR, TYPE_SIZE(type), flexsize); | |
523 | ||
524 | return; | |
525 | } | |
526 | ||
527 | ||
528 | static void randomize_layout_finish_decl(void *event_data, void *data) | |
529 | { | |
530 | tree decl = (tree)event_data; | |
531 | tree type; | |
532 | ||
533 | if (decl == NULL_TREE || decl == error_mark_node) | |
534 | return; | |
535 | ||
536 | type = TREE_TYPE(decl); | |
537 | ||
538 | if (TREE_CODE(decl) != VAR_DECL) | |
539 | return; | |
540 | ||
541 | if (TREE_CODE(type) != RECORD_TYPE && TREE_CODE(type) != UNION_TYPE) | |
542 | return; | |
543 | ||
544 | if (!lookup_attribute("randomize_performed", TYPE_ATTRIBUTES(type))) | |
545 | return; | |
546 | ||
547 | DECL_SIZE(decl) = 0; | |
548 | DECL_SIZE_UNIT(decl) = 0; | |
549 | SET_DECL_ALIGN(decl, 0); | |
550 | SET_DECL_MODE (decl, VOIDmode); | |
551 | SET_DECL_RTL(decl, 0); | |
552 | update_decl_size(decl); | |
553 | layout_decl(decl, 0); | |
554 | } | |
555 | ||
556 | static void finish_type(void *event_data, void *data) | |
557 | { | |
558 | tree type = (tree)event_data; | |
559 | ||
560 | if (type == NULL_TREE || type == error_mark_node) | |
561 | return; | |
562 | ||
563 | if (TREE_CODE(type) != RECORD_TYPE) | |
564 | return; | |
565 | ||
566 | if (TYPE_FIELDS(type) == NULL_TREE) | |
567 | return; | |
568 | ||
569 | if (lookup_attribute("randomize_considered", TYPE_ATTRIBUTES(type))) | |
570 | return; | |
571 | ||
572 | #ifdef __DEBUG_PLUGIN | |
573 | fprintf(stderr, "Calling randomize_type on %s\n", ORIG_TYPE_NAME(type)); | |
574 | #endif | |
575 | #ifdef __DEBUG_VERBOSE | |
576 | debug_tree(type); | |
577 | #endif | |
578 | randomize_type(type); | |
579 | ||
580 | return; | |
581 | } | |
582 | ||
583 | static struct attribute_spec randomize_layout_attr = { | |
584 | .name = "randomize_layout", | |
585 | // related to args | |
586 | .min_length = 0, | |
587 | .max_length = 0, | |
588 | .decl_required = false, | |
589 | // need type declaration | |
590 | .type_required = true, | |
591 | .function_type_required = false, | |
592 | .handler = handle_randomize_layout_attr, | |
593 | #if BUILDING_GCC_VERSION >= 4007 | |
594 | .affects_type_identity = true | |
595 | #endif | |
596 | }; | |
597 | ||
598 | static struct attribute_spec no_randomize_layout_attr = { | |
599 | .name = "no_randomize_layout", | |
600 | // related to args | |
601 | .min_length = 0, | |
602 | .max_length = 0, | |
603 | .decl_required = false, | |
604 | // need type declaration | |
605 | .type_required = true, | |
606 | .function_type_required = false, | |
607 | .handler = handle_randomize_layout_attr, | |
608 | #if BUILDING_GCC_VERSION >= 4007 | |
609 | .affects_type_identity = true | |
610 | #endif | |
611 | }; | |
612 | ||
613 | static struct attribute_spec randomize_considered_attr = { | |
614 | .name = "randomize_considered", | |
615 | // related to args | |
616 | .min_length = 0, | |
617 | .max_length = 0, | |
618 | .decl_required = false, | |
619 | // need type declaration | |
620 | .type_required = true, | |
621 | .function_type_required = false, | |
622 | .handler = handle_randomize_considered_attr, | |
623 | #if BUILDING_GCC_VERSION >= 4007 | |
624 | .affects_type_identity = false | |
625 | #endif | |
626 | }; | |
627 | ||
628 | static struct attribute_spec randomize_performed_attr = { | |
629 | .name = "randomize_performed", | |
630 | // related to args | |
631 | .min_length = 0, | |
632 | .max_length = 0, | |
633 | .decl_required = false, | |
634 | // need type declaration | |
635 | .type_required = true, | |
636 | .function_type_required = false, | |
637 | .handler = handle_randomize_performed_attr, | |
638 | #if BUILDING_GCC_VERSION >= 4007 | |
639 | .affects_type_identity = false | |
640 | #endif | |
641 | }; | |
642 | ||
643 | static void register_attributes(void *event_data, void *data) | |
644 | { | |
645 | register_attribute(&randomize_layout_attr); | |
646 | register_attribute(&no_randomize_layout_attr); | |
647 | register_attribute(&randomize_considered_attr); | |
648 | register_attribute(&randomize_performed_attr); | |
649 | } | |
650 | ||
651 | static void check_bad_casts_in_constructor(tree var, tree init) | |
652 | { | |
653 | unsigned HOST_WIDE_INT idx; | |
654 | tree field, val; | |
655 | tree field_type, val_type; | |
656 | ||
657 | FOR_EACH_CONSTRUCTOR_ELT(CONSTRUCTOR_ELTS(init), idx, field, val) { | |
658 | if (TREE_CODE(val) == CONSTRUCTOR) { | |
659 | check_bad_casts_in_constructor(var, val); | |
660 | continue; | |
661 | } | |
662 | ||
663 | /* pipacs' plugin creates franken-arrays that differ from those produced by | |
664 | normal code which all have valid 'field' trees. work around this */ | |
665 | if (field == NULL_TREE) | |
666 | continue; | |
667 | field_type = TREE_TYPE(field); | |
668 | val_type = TREE_TYPE(val); | |
669 | ||
670 | if (TREE_CODE(field_type) != POINTER_TYPE || TREE_CODE(val_type) != POINTER_TYPE) | |
671 | continue; | |
672 | ||
673 | if (field_type == val_type) | |
674 | continue; | |
675 | ||
676 | field_type = TYPE_MAIN_VARIANT(strip_array_types(TYPE_MAIN_VARIANT(TREE_TYPE(field_type)))); | |
677 | val_type = TYPE_MAIN_VARIANT(strip_array_types(TYPE_MAIN_VARIANT(TREE_TYPE(val_type)))); | |
678 | ||
679 | if (field_type == void_type_node) | |
680 | continue; | |
681 | if (field_type == val_type) | |
682 | continue; | |
683 | if (TREE_CODE(val_type) != RECORD_TYPE) | |
684 | continue; | |
685 | ||
686 | if (!lookup_attribute("randomize_performed", TYPE_ATTRIBUTES(val_type))) | |
687 | continue; | |
688 | MISMATCH(DECL_SOURCE_LOCATION(var), "constructor\n", TYPE_MAIN_VARIANT(field_type), TYPE_MAIN_VARIANT(val_type)); | |
689 | } | |
690 | } | |
691 | ||
692 | /* derived from the constify plugin */ | |
693 | static void check_global_variables(void *event_data, void *data) | |
694 | { | |
695 | struct varpool_node *node; | |
696 | tree init; | |
697 | ||
698 | FOR_EACH_VARIABLE(node) { | |
699 | tree var = NODE_DECL(node); | |
700 | init = DECL_INITIAL(var); | |
701 | if (init == NULL_TREE) | |
702 | continue; | |
703 | ||
704 | if (TREE_CODE(init) != CONSTRUCTOR) | |
705 | continue; | |
706 | ||
707 | check_bad_casts_in_constructor(var, init); | |
708 | } | |
709 | } | |
710 | ||
711 | static bool dominated_by_is_err(const_tree rhs, basic_block bb) | |
712 | { | |
713 | basic_block dom; | |
714 | gimple dom_stmt; | |
715 | gimple call_stmt; | |
716 | const_tree dom_lhs; | |
717 | const_tree poss_is_err_cond; | |
718 | const_tree poss_is_err_func; | |
719 | const_tree is_err_arg; | |
720 | ||
721 | dom = get_immediate_dominator(CDI_DOMINATORS, bb); | |
722 | if (!dom) | |
723 | return false; | |
724 | ||
725 | dom_stmt = last_stmt(dom); | |
726 | if (!dom_stmt) | |
727 | return false; | |
728 | ||
729 | if (gimple_code(dom_stmt) != GIMPLE_COND) | |
730 | return false; | |
731 | ||
732 | if (gimple_cond_code(dom_stmt) != NE_EXPR) | |
733 | return false; | |
734 | ||
735 | if (!integer_zerop(gimple_cond_rhs(dom_stmt))) | |
736 | return false; | |
737 | ||
738 | poss_is_err_cond = gimple_cond_lhs(dom_stmt); | |
739 | ||
740 | if (TREE_CODE(poss_is_err_cond) != SSA_NAME) | |
741 | return false; | |
742 | ||
743 | call_stmt = SSA_NAME_DEF_STMT(poss_is_err_cond); | |
744 | ||
745 | if (gimple_code(call_stmt) != GIMPLE_CALL) | |
746 | return false; | |
747 | ||
748 | dom_lhs = gimple_get_lhs(call_stmt); | |
749 | poss_is_err_func = gimple_call_fndecl(call_stmt); | |
750 | if (!poss_is_err_func) | |
751 | return false; | |
752 | if (dom_lhs != poss_is_err_cond) | |
753 | return false; | |
754 | if (strcmp(DECL_NAME_POINTER(poss_is_err_func), "IS_ERR")) | |
755 | return false; | |
756 | ||
757 | is_err_arg = gimple_call_arg(call_stmt, 0); | |
758 | if (!is_err_arg) | |
759 | return false; | |
760 | ||
761 | if (is_err_arg != rhs) | |
762 | return false; | |
763 | ||
764 | return true; | |
765 | } | |
766 | ||
767 | static void handle_local_var_initializers(void) | |
768 | { | |
769 | tree var; | |
770 | unsigned int i; | |
771 | ||
772 | FOR_EACH_LOCAL_DECL(cfun, i, var) { | |
773 | tree init = DECL_INITIAL(var); | |
774 | if (!init) | |
775 | continue; | |
776 | if (TREE_CODE(init) != CONSTRUCTOR) | |
777 | continue; | |
778 | check_bad_casts_in_constructor(var, init); | |
779 | } | |
780 | } | |
781 | ||
782 | static bool type_name_eq(gimple stmt, const_tree type_tree, const char *wanted_name) | |
783 | { | |
784 | const char *type_name; | |
785 | ||
786 | if (type_tree == NULL_TREE) | |
787 | return false; | |
788 | ||
789 | switch (TREE_CODE(type_tree)) { | |
790 | case RECORD_TYPE: | |
791 | type_name = TYPE_NAME_POINTER(type_tree); | |
792 | break; | |
793 | case INTEGER_TYPE: | |
794 | if (TYPE_PRECISION(type_tree) == CHAR_TYPE_SIZE) | |
795 | type_name = "char"; | |
796 | else { | |
797 | INFORM(gimple_location(stmt), "found non-char INTEGER_TYPE cast comparison: %qT\n", type_tree); | |
798 | debug_tree(type_tree); | |
799 | return false; | |
800 | } | |
801 | break; | |
802 | case POINTER_TYPE: | |
803 | if (TREE_CODE(TREE_TYPE(type_tree)) == VOID_TYPE) { | |
804 | type_name = "void *"; | |
805 | break; | |
806 | } else { | |
807 | INFORM(gimple_location(stmt), "found non-void POINTER_TYPE cast comparison %qT\n", type_tree); | |
808 | debug_tree(type_tree); | |
809 | return false; | |
810 | } | |
811 | default: | |
812 | INFORM(gimple_location(stmt), "unhandled cast comparison: %qT\n", type_tree); | |
813 | debug_tree(type_tree); | |
814 | return false; | |
815 | } | |
816 | ||
817 | return strcmp(type_name, wanted_name) == 0; | |
818 | } | |
819 | ||
820 | static bool whitelisted_cast(gimple stmt, const_tree lhs_tree, const_tree rhs_tree) | |
821 | { | |
822 | const struct whitelist_entry *entry; | |
823 | expanded_location xloc = expand_location(gimple_location(stmt)); | |
824 | ||
825 | for (entry = whitelist; entry->pathname; entry++) { | |
826 | if (!strstr(xloc.file, entry->pathname)) | |
827 | continue; | |
828 | ||
829 | if (type_name_eq(stmt, lhs_tree, entry->lhs) && type_name_eq(stmt, rhs_tree, entry->rhs)) | |
830 | return true; | |
831 | } | |
832 | ||
833 | return false; | |
834 | } | |
835 | ||
836 | /* | |
837 | * iterate over all statements to find "bad" casts: | |
838 | * those where the address of the start of a structure is cast | |
839 | * to a pointer of a structure of a different type, or a | |
840 | * structure pointer type is cast to a different structure pointer type | |
841 | */ | |
842 | static unsigned int find_bad_casts_execute(void) | |
843 | { | |
844 | basic_block bb; | |
845 | ||
846 | handle_local_var_initializers(); | |
847 | ||
848 | FOR_EACH_BB_FN(bb, cfun) { | |
849 | gimple_stmt_iterator gsi; | |
850 | ||
851 | for (gsi = gsi_start_bb(bb); !gsi_end_p(gsi); gsi_next(&gsi)) { | |
852 | gimple stmt; | |
853 | const_tree lhs; | |
854 | const_tree lhs_type; | |
855 | const_tree rhs1; | |
856 | const_tree rhs_type; | |
857 | const_tree ptr_lhs_type; | |
858 | const_tree ptr_rhs_type; | |
859 | const_tree op0; | |
860 | const_tree op0_type; | |
861 | enum tree_code rhs_code; | |
862 | ||
863 | stmt = gsi_stmt(gsi); | |
864 | ||
865 | #ifdef __DEBUG_PLUGIN | |
866 | #ifdef __DEBUG_VERBOSE | |
867 | debug_gimple_stmt(stmt); | |
868 | debug_tree(gimple_get_lhs(stmt)); | |
869 | #endif | |
870 | #endif | |
871 | ||
872 | if (gimple_code(stmt) != GIMPLE_ASSIGN) | |
873 | continue; | |
874 | ||
875 | #ifdef __DEBUG_PLUGIN | |
876 | #ifdef __DEBUG_VERBOSE | |
877 | debug_tree(gimple_assign_rhs1(stmt)); | |
878 | #endif | |
879 | #endif | |
880 | ||
881 | ||
882 | rhs_code = gimple_assign_rhs_code(stmt); | |
883 | ||
884 | if (rhs_code != ADDR_EXPR && rhs_code != SSA_NAME) | |
885 | continue; | |
886 | ||
887 | lhs = gimple_get_lhs(stmt); | |
888 | lhs_type = TREE_TYPE(lhs); | |
889 | rhs1 = gimple_assign_rhs1(stmt); | |
890 | rhs_type = TREE_TYPE(rhs1); | |
891 | ||
892 | if (TREE_CODE(rhs_type) != POINTER_TYPE || | |
893 | TREE_CODE(lhs_type) != POINTER_TYPE) | |
894 | continue; | |
895 | ||
896 | ptr_lhs_type = TYPE_MAIN_VARIANT(strip_array_types(TYPE_MAIN_VARIANT(TREE_TYPE(lhs_type)))); | |
897 | ptr_rhs_type = TYPE_MAIN_VARIANT(strip_array_types(TYPE_MAIN_VARIANT(TREE_TYPE(rhs_type)))); | |
898 | ||
899 | if (ptr_rhs_type == void_type_node) | |
900 | continue; | |
901 | ||
902 | if (ptr_lhs_type == void_type_node) | |
903 | continue; | |
904 | ||
905 | if (dominated_by_is_err(rhs1, bb)) | |
906 | continue; | |
907 | ||
908 | if (TREE_CODE(ptr_rhs_type) != RECORD_TYPE) { | |
909 | #ifndef __DEBUG_PLUGIN | |
910 | if (lookup_attribute("randomize_performed", TYPE_ATTRIBUTES(ptr_lhs_type))) | |
911 | #endif | |
912 | { | |
913 | if (!whitelisted_cast(stmt, ptr_lhs_type, ptr_rhs_type)) | |
914 | MISMATCH(gimple_location(stmt), "rhs", ptr_lhs_type, ptr_rhs_type); | |
915 | } | |
916 | continue; | |
917 | } | |
918 | ||
919 | if (rhs_code == SSA_NAME && ptr_lhs_type == ptr_rhs_type) | |
920 | continue; | |
921 | ||
922 | if (rhs_code == ADDR_EXPR) { | |
923 | op0 = TREE_OPERAND(rhs1, 0); | |
924 | ||
925 | if (op0 == NULL_TREE) | |
926 | continue; | |
927 | ||
928 | if (TREE_CODE(op0) != VAR_DECL) | |
929 | continue; | |
930 | ||
931 | op0_type = TYPE_MAIN_VARIANT(strip_array_types(TYPE_MAIN_VARIANT(TREE_TYPE(op0)))); | |
932 | if (op0_type == ptr_lhs_type) | |
933 | continue; | |
934 | ||
935 | #ifndef __DEBUG_PLUGIN | |
936 | if (lookup_attribute("randomize_performed", TYPE_ATTRIBUTES(op0_type))) | |
937 | #endif | |
938 | { | |
939 | if (!whitelisted_cast(stmt, ptr_lhs_type, op0_type)) | |
940 | MISMATCH(gimple_location(stmt), "op0", ptr_lhs_type, op0_type); | |
941 | } | |
942 | } else { | |
943 | const_tree ssa_name_var = SSA_NAME_VAR(rhs1); | |
944 | /* skip bogus type casts introduced by container_of */ | |
945 | if (ssa_name_var != NULL_TREE && DECL_NAME(ssa_name_var) && | |
946 | !strcmp((const char *)DECL_NAME_POINTER(ssa_name_var), "__mptr")) | |
947 | continue; | |
948 | #ifndef __DEBUG_PLUGIN | |
949 | if (lookup_attribute("randomize_performed", TYPE_ATTRIBUTES(ptr_rhs_type))) | |
950 | #endif | |
951 | { | |
952 | if (!whitelisted_cast(stmt, ptr_lhs_type, ptr_rhs_type)) | |
953 | MISMATCH(gimple_location(stmt), "ssa", ptr_lhs_type, ptr_rhs_type); | |
954 | } | |
955 | } | |
956 | ||
957 | } | |
958 | } | |
959 | return 0; | |
960 | } | |
961 | ||
962 | #define PASS_NAME find_bad_casts | |
963 | #define NO_GATE | |
964 | #define TODO_FLAGS_FINISH TODO_dump_func | |
965 | #include "gcc-generate-gimple-pass.h" | |
966 | ||
967 | __visible int plugin_init(struct plugin_name_args *plugin_info, struct plugin_gcc_version *version) | |
968 | { | |
969 | int i; | |
970 | const char * const plugin_name = plugin_info->base_name; | |
971 | const int argc = plugin_info->argc; | |
972 | const struct plugin_argument * const argv = plugin_info->argv; | |
973 | bool enable = true; | |
974 | int obtained_seed = 0; | |
975 | struct register_pass_info find_bad_casts_pass_info; | |
976 | ||
977 | find_bad_casts_pass_info.pass = make_find_bad_casts_pass(); | |
978 | find_bad_casts_pass_info.reference_pass_name = "ssa"; | |
979 | find_bad_casts_pass_info.ref_pass_instance_number = 1; | |
980 | find_bad_casts_pass_info.pos_op = PASS_POS_INSERT_AFTER; | |
981 | ||
982 | if (!plugin_default_version_check(version, &gcc_version)) { | |
983 | error(G_("incompatible gcc/plugin versions")); | |
984 | return 1; | |
985 | } | |
986 | ||
987 | if (strncmp(lang_hooks.name, "GNU C", 5) && !strncmp(lang_hooks.name, "GNU C+", 6)) { | |
988 | inform(UNKNOWN_LOCATION, G_("%s supports C only, not %s"), plugin_name, lang_hooks.name); | |
989 | enable = false; | |
990 | } | |
991 | ||
992 | for (i = 0; i < argc; ++i) { | |
993 | if (!strcmp(argv[i].key, "disable")) { | |
994 | enable = false; | |
995 | continue; | |
996 | } | |
997 | if (!strcmp(argv[i].key, "performance-mode")) { | |
998 | performance_mode = 1; | |
999 | continue; | |
1000 | } | |
1001 | error(G_("unknown option '-fplugin-arg-%s-%s'"), plugin_name, argv[i].key); | |
1002 | } | |
1003 | ||
1004 | if (strlen(randstruct_seed) != 64) { | |
1005 | error(G_("invalid seed value supplied for %s plugin"), plugin_name); | |
1006 | return 1; | |
1007 | } | |
1008 | obtained_seed = sscanf(randstruct_seed, "%016llx%016llx%016llx%016llx", | |
1009 | &shuffle_seed[0], &shuffle_seed[1], &shuffle_seed[2], &shuffle_seed[3]); | |
1010 | if (obtained_seed != 4) { | |
1011 | error(G_("Invalid seed supplied for %s plugin"), plugin_name); | |
1012 | return 1; | |
1013 | } | |
1014 | ||
1015 | register_callback(plugin_name, PLUGIN_INFO, NULL, &randomize_layout_plugin_info); | |
1016 | if (enable) { | |
1017 | register_callback(plugin_name, PLUGIN_ALL_IPA_PASSES_START, check_global_variables, NULL); | |
1018 | register_callback(plugin_name, PLUGIN_PASS_MANAGER_SETUP, NULL, &find_bad_casts_pass_info); | |
1019 | register_callback(plugin_name, PLUGIN_FINISH_TYPE, finish_type, NULL); | |
1020 | register_callback(plugin_name, PLUGIN_FINISH_DECL, randomize_layout_finish_decl, NULL); | |
1021 | } | |
1022 | register_callback(plugin_name, PLUGIN_ATTRIBUTES, register_attributes, NULL); | |
1023 | ||
1024 | return 0; | |
1025 | } |