0073af326449864b4da5f7a64677c0de2d5eafa2
[muen/linux.git] / scripts / gcc-plugins / randomize_layout_plugin.c
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[] = {
49         /* NIU overloads mapping with page struct */
50         { "drivers/net/ethernet/sun/niu.c", "page", "address_space" },
51         /* unix_skb_parms via UNIXCB() buffer */
52         { "net/unix/af_unix.c", "unix_skb_parms", "char" },
53         /* big_key payload.data struct splashing */
54         { "security/keys/big_key.c", "path", "void *" },
55         /* walk struct security_hook_heads as an array of struct list_head */
56         { "security/security.c", "list_head", "security_hook_heads" },
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
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 }