?  search:
summary | log | graphiclog1 | graphiclog2 | commit | commitdiff | tree | refs | edit | fork
blame | history | raw | HEAD
comparison: improve "foo = min(...);" assignment handling
[smatch.git] / check_user_data2.c
blob7c11b589744c59cbf0c3a6405d40752dc087305e
1 /*
2 * Copyright (C) 2011 Dan Carpenter.
3 *
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU General Public License
6 * as published by the Free Software Foundation; either version 2
7 * of the License, or (at your option) any later version.
8 *
9 * This program is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 * GNU General Public License for more details.
13 *
14 * You should have received a copy of the GNU General Public License
15 * along with this program; if not, see http://www.gnu.org/copyleft/gpl.txt
16 */
17
18 /*
19 * There are a couple checks that try to see if a variable
20 * comes from the user. It would be better to unify them
21 * into one place. Also it we should follow the data down
22 * the call paths. Hence this file.
23 */
24
25 #include "smatch.h"
26 #include "smatch_slist.h"
27 #include "smatch_extra.h"
28
29 static int my_id;
30 static int my_call_id;
31
32 STATE(called);
33 static bool func_gets_user_data;
34
35 static const char * kstr_funcs[] = {
36 "kstrtoull", "kstrtoll", "kstrtoul", "kstrtol", "kstrtouint",
37 "kstrtoint", "kstrtou64", "kstrtos64", "kstrtou32", "kstrtos32",
38 "kstrtou16", "kstrtos16", "kstrtou8", "kstrtos8", "kstrtoull_from_user"
39 "kstrtoll_from_user", "kstrtoul_from_user", "kstrtol_from_user",
40 "kstrtouint_from_user", "kstrtoint_from_user", "kstrtou16_from_user",
41 "kstrtos16_from_user", "kstrtou8_from_user", "kstrtos8_from_user",
42 "kstrtou64_from_user", "kstrtos64_from_user", "kstrtou32_from_user",
43 "kstrtos32_from_user",
44 };
45
46 static const char *returns_user_data[] = {
47 "simple_strtol", "simple_strtoll", "simple_strtoul", "simple_strtoull",
48 "kvm_register_read", "nlmsg_data", "nla_data", "memdup_user",
49 "kmap_atomic", "skb_network_header",
50 };
51
52 static void set_points_to_user_data(struct expression *expr);
53
54 static struct stree *start_states;
55 static struct stree_stack *saved_stack;
56 static void save_start_states(struct statement *stmt)
57 {
58 start_states = clone_stree(__get_cur_stree());
59 }
60
61 static void free_start_states(void)
62 {
63 free_stree(&start_states);
64 }
65
66 static void match_save_states(struct expression *expr)
67 {
68 push_stree(&saved_stack, start_states);
69 start_states = NULL;
70 }
71
72 static void match_restore_states(struct expression *expr)
73 {
74 free_stree(&start_states);
75 start_states = pop_stree(&saved_stack);
76 }
77
78 static struct smatch_state *empty_state(struct sm_state *sm)
79 {
80 return alloc_estate_empty();
81 }
82
83 static void pre_merge_hook(struct sm_state *sm)
84 {
85 struct smatch_state *user;
86 struct smatch_state *extra;
87 struct range_list *rl;
88 sval_t dummy;
89 sval_t sval_100 = {
90 .type = &int_ctype,
91 .value = 100,
92 };
93
94 user = get_state(my_id, sm->name, sm->sym);
95 if (!user)
96 return;
97 if (!__in_function_def && !estate_rl(sm->state)) {
98 /*
99 * If the one side is capped and the other side is empty then
100 * let's just mark it as not-user data because the information
101 * isn't going to be useful. How this looks is:
102 *
103 * if (user_var > trusted)
104 * user_var = trusted; <-- empty state
105 * else
106 * <-- capped
107 *
108 * The problem is that sometimes things are capped to a literal
109 * and we'd like to keep the state in that case... Ugh. I've
110 * added a check which assumes that everything less than 100 is
111 * probably capped against a literal.
112 *
113 */
114 if (is_capped_var_sym(sm->name, sm->sym) &&
115 sval_cmp(estate_max(user), sval_100) > 0)
116 set_state(my_id, sm->name, sm->sym, alloc_estate_empty());
117 return;
118 }
119 extra = get_state(SMATCH_EXTRA, sm->name, sm->sym);
120 if (!extra || !estate_rl(extra))
121 return;
122 rl = rl_intersection(estate_rl(user), estate_rl(extra));
123 if (rl_to_sval(rl, &dummy))
124 rl = NULL;
125 set_state(my_id, sm->name, sm->sym, alloc_estate_rl(clone_rl(rl)));
126 }
127
128 static void extra_nomod_hook(const char *name, struct symbol *sym, struct expression *expr, struct smatch_state *state)
129 {
130 struct smatch_state *user;
131 struct range_list *rl;
132
133 user = get_state(my_id, name, sym);
134 if (!user)
135 return;
136 rl = rl_intersection(estate_rl(user), estate_rl(state));
137 if (rl_equiv(rl, estate_rl(user)))
138 return;
139 set_state(my_id, name, sym, alloc_estate_rl(rl));
140 }
141
142 static void tag_inner_struct_members(struct expression *expr, struct symbol *member)
143 {
144 struct expression *edge_member;
145 struct symbol *base = get_real_base_type(member);
146 struct symbol *tmp;
147
148 if (member->ident)
149 expr = member_expression(expr, '.', member->ident);
150
151 FOR_EACH_PTR(base->symbol_list, tmp) {
152 struct symbol *type;
153
154 type = get_real_base_type(tmp);
155 if (!type)
156 continue;
157
158 if (type->type == SYM_UNION || type->type == SYM_STRUCT) {
159 tag_inner_struct_members(expr, tmp);
160 continue;
161 }
162
163 if (!tmp->ident)
164 continue;
165
166 edge_member = member_expression(expr, '.', tmp->ident);
167 set_state_expr(my_id, edge_member, alloc_estate_whole(type));
168 } END_FOR_EACH_PTR(tmp);
169 }
170
171 static void tag_struct_members(struct symbol *type, struct expression *expr)
172 {
173 struct symbol *tmp;
174 struct expression *member;
175 int op = '*';
176
177 if (expr->type == EXPR_PREOP && expr->op == '&') {
178 expr = strip_expr(expr->unop);
179 op = '.';
180 }
181
182 FOR_EACH_PTR(type->symbol_list, tmp) {
183 type = get_real_base_type(tmp);
184 if (!type)
185 continue;
186
187 if (type->type == SYM_UNION || type->type == SYM_STRUCT) {
188 tag_inner_struct_members(expr, tmp);
189 continue;
190 }
191
192 if (!tmp->ident)
193 continue;
194
195 member = member_expression(expr, op, tmp->ident);
196 set_state_expr(my_id, member, alloc_estate_whole(get_type(member)));
197
198 if (type->type == SYM_ARRAY)
199 set_points_to_user_data(member);
200 } END_FOR_EACH_PTR(tmp);
201 }
202
203 static void tag_base_type(struct expression *expr)
204 {
205 if (expr->type == EXPR_PREOP && expr->op == '&')
206 expr = strip_expr(expr->unop);
207 else
208 expr = deref_expression(expr);
209 set_state_expr(my_id, expr, alloc_estate_whole(get_type(expr)));
210 }
211
212 static void tag_as_user_data(struct expression *expr)
213 {
214 struct symbol *type;
215
216 expr = strip_expr(expr);
217
218 type = get_type(expr);
219 if (!type || type->type != SYM_PTR)
220 return;
221 type = get_real_base_type(type);
222 if (!type)
223 return;
224 if (type == &void_ctype) {
225 set_state_expr(my_id, deref_expression(expr), alloc_estate_whole(&ulong_ctype));
226 return;
227 }
228 if (type->type == SYM_BASETYPE)
229 tag_base_type(expr);
230 if (type->type == SYM_STRUCT || type->type == SYM_UNION) {
231 if (expr->type != EXPR_PREOP || expr->op != '&')
232 expr = deref_expression(expr);
233 else
234 set_state_expr(my_id, deref_expression(expr), alloc_estate_whole(&ulong_ctype));
235 tag_struct_members(type, expr);
236 }
237 }
238
239 static void match_user_copy(const char *fn, struct expression *expr, void *_param)
240 {
241 int param = PTR_INT(_param);
242 struct expression *dest;
243
244 func_gets_user_data = true;
245
246 dest = get_argument_from_call_expr(expr->args, param);
247 dest = strip_expr(dest);
248 if (!dest)
249 return;
250 tag_as_user_data(dest);
251 }
252
253 static int is_dev_attr_name(struct expression *expr)
254 {
255 char *name;
256 int ret = 0;
257
258 name = expr_to_str(expr);
259 if (!name)
260 return 0;
261 if (strstr(name, "->attr.name"))
262 ret = 1;
263 free_string(name);
264 return ret;
265 }
266
267 static int ends_in_n(struct expression *expr)
268 {
269 struct string *str;
270
271 if (!expr)
272 return 0;
273 if (expr->type != EXPR_STRING || !expr->string)
274 return 0;
275
276 str = expr->string;
277 if (str->length < 3)
278 return 0;
279
280 if (str->data[str->length - 3] == '%' &&
281 str->data[str->length - 2] == 'n')
282 return 1;
283 return 0;
284 }
285
286 static void match_sscanf(const char *fn, struct expression *expr, void *unused)
287 {
288 struct expression *str, *format, *arg;
289 int i, last;
290
291 func_gets_user_data = true;
292
293 str = get_argument_from_call_expr(expr->args, 0);
294 if (is_dev_attr_name(str))
295 return;
296
297 format = get_argument_from_call_expr(expr->args, 1);
298 if (is_dev_attr_name(format))
299 return;
300
301 last = ptr_list_size((struct ptr_list *)expr->args) - 1;
302
303 i = -1;
304 FOR_EACH_PTR(expr->args, arg) {
305 i++;
306 if (i < 2)
307 continue;
308 if (i == last && ends_in_n(format))
309 continue;
310 tag_as_user_data(arg);
311 } END_FOR_EACH_PTR(arg);
312 }
313
314 static int is_skb_data(struct expression *expr)
315 {
316 struct symbol *sym;
317
318 if (!expr)
319 return 0;
320
321 if (expr->type == EXPR_BINOP && expr->op == '+')
322 return is_skb_data(expr->left);
323
324 expr = strip_expr(expr);
325 if (!expr)
326 return 0;
327 if (expr->type != EXPR_DEREF || expr->op != '.')
328 return 0;
329
330 if (!expr->member)
331 return 0;
332 if (strcmp(expr->member->name, "data") != 0)
333 return 0;
334
335 sym = expr_to_sym(expr->deref);
336 if (!sym)
337 return 0;
338 sym = get_real_base_type(sym);
339 if (!sym || sym->type != SYM_PTR)
340 return 0;
341 sym = get_real_base_type(sym);
342 if (!sym || sym->type != SYM_STRUCT || !sym->ident)
343 return 0;
344 if (strcmp(sym->ident->name, "sk_buff") != 0)
345 return 0;
346
347 return 1;
348 }
349
350 static int get_rl_from_function(struct expression *expr, struct range_list **rl)
351 {
352 int i;
353
354 if (expr->type != EXPR_CALL || expr->fn->type != EXPR_SYMBOL ||
355 !expr->fn->symbol_name || !expr->fn->symbol_name->name)
356 return 0;
357
358 for (i = 0; i < ARRAY_SIZE(returns_user_data); i++) {
359 if (strcmp(expr->fn->symbol_name->name, returns_user_data[i]) == 0) {
360 *rl = alloc_whole_rl(get_type(expr));
361 return 1;
362 }
363 }
364 return 0;
365 }
366
367 int points_to_user_data(struct expression *expr)
368 {
369 struct smatch_state *state;
370 struct range_list *rl;
371 char buf[256];
372 struct symbol *sym;
373 char *name;
374 int ret = 0;
375
376 expr = strip_expr(expr);
377 if (!expr)
378 return 0;
379 if (is_skb_data(expr))
380 return 1;
381 if (get_rl_from_function(expr, &rl))
382 return 1;
383
384 if (expr->type == EXPR_BINOP && expr->op == '+') {
385 if (points_to_user_data(expr->left))
386 return 1;
387 if (points_to_user_data(expr->right))
388 return 1;
389 return 0;
390 }
391
392 name = expr_to_var_sym(expr, &sym);
393 if (!name || !sym)
394 goto free;
395 snprintf(buf, sizeof(buf), "*%s", name);
396 state = get_state(my_id, buf, sym);
397 if (state && estate_rl(state))
398 ret = 1;
399 free:
400 free_string(name);
401 return ret;
402 }
403
404 static void set_points_to_user_data(struct expression *expr)
405 {
406 char *name;
407 struct symbol *sym;
408 char buf[256];
409
410 name = expr_to_var_sym(expr, &sym);
411 if (!name || !sym)
412 goto free;
413 snprintf(buf, sizeof(buf), "*%s", name);
414 set_state(my_id, buf, sym, alloc_estate_whole(&llong_ctype));
415 free:
416 free_string(name);
417 }
418
419 static int comes_from_skb_data(struct expression *expr)
420 {
421 expr = strip_expr(expr);
422 if (!expr || expr->type != EXPR_PREOP || expr->op != '*')
423 return 0;
424
425 expr = strip_expr(expr->unop);
426 if (!expr)
427 return 0;
428 if (expr->type == EXPR_BINOP && expr->op == '+')
429 expr = strip_expr(expr->left);
430
431 return is_skb_data(expr);
432 }
433
434 static int handle_struct_assignment(struct expression *expr)
435 {
436 struct expression *right;
437 struct symbol *left_type, *right_type;
438
439 left_type = get_type(expr->left);
440 if (!left_type || left_type->type != SYM_PTR)
441 return 0;
442 left_type = get_real_base_type(left_type);
443 if (!left_type)
444 return 0;
445 if (left_type->type != SYM_STRUCT &&
446 left_type->type != SYM_UNION)
447 return 0;
448
449 /*
450 * Ignore struct to struct assignments because for those we look at the
451 * individual members.
452 */
453 right = strip_expr(expr->right);
454 right_type = get_type(right);
455 if (!right_type || right_type->type != SYM_PTR)
456 return 0;
457
458 /* If we are assigning struct members then normally that is handled
459 * by fake assignments, however if we cast one struct to a different
460 * of struct then we handle that here.
461 */
462 right_type = get_real_base_type(right_type);
463 if (right_type == left_type)
464 return 0;
465
466 if (!points_to_user_data(right))
467 return 0;
468
469 tag_as_user_data(expr->left);
470 return 1;
471 }
472
473 static int handle_get_user(struct expression *expr)
474 {
475 char *name;
476 int ret = 0;
477
478 name = get_macro_name(expr->pos);
479 if (!name || strcmp(name, "get_user") != 0)
480 return 0;
481
482 name = expr_to_var(expr->right);
483 if (!name || strcmp(name, "__val_gu") != 0)
484 goto free;
485 set_state_expr(my_id, expr->left, alloc_estate_whole(get_type(expr->left)));
486 ret = 1;
487 free:
488 free_string(name);
489 return ret;
490 }
491
492 static void match_assign(struct expression *expr)
493 {
494 struct range_list *rl;
495
496 if (is_fake_call(expr->right))
497 goto clear_old_state;
498 if (handle_get_user(expr))
499 return;
500 if (points_to_user_data(expr->right))
501 set_points_to_user_data(expr->left);
502 if (handle_struct_assignment(expr))
503 return;
504
505 if (!get_user_rl(expr->right, &rl))
506 goto clear_old_state;
507
508 rl = cast_rl(get_type(expr->left), rl);
509 set_state_expr(my_id, expr->left, alloc_estate_rl(rl));
510
511 return;
512
513 clear_old_state:
514 if (get_state_expr(my_id, expr->left))
515 set_state_expr(my_id, expr->left, alloc_estate_empty());
516 }
517
518 static void handle_eq_noteq(struct expression *expr)
519 {
520 struct smatch_state *left_orig, *right_orig;
521
522 left_orig = get_state_expr(my_id, expr->left);
523 right_orig = get_state_expr(my_id, expr->right);
524
525 if (!left_orig && !right_orig)
526 return;
527 if (left_orig && right_orig)
528 return;
529
530 if (left_orig) {
531 set_true_false_states_expr(my_id, expr->left,
532 expr->op == SPECIAL_EQUAL ? alloc_estate_empty() : NULL,
533 expr->op == SPECIAL_EQUAL ? NULL : alloc_estate_empty());
534 } else {
535 set_true_false_states_expr(my_id, expr->right,
536 expr->op == SPECIAL_EQUAL ? alloc_estate_empty() : NULL,
537 expr->op == SPECIAL_EQUAL ? NULL : alloc_estate_empty());
538 }
539 }
540
541 static void handle_unsigned_lt_gt(struct expression *expr)
542 {
543 struct symbol *type;
544 struct range_list *left;
545 struct range_list *right;
546 struct range_list *non_negative;
547 sval_t min, minus_one;
548
549 /*
550 * conditions are mostly handled by smatch_extra.c. The special case
551 * here is that say you have if (user_int < unknown_u32) {
552 * In Smatch extra we say that, We have no idea what value
553 * unknown_u32 is so the only thin we can say for sure is that
554 * user_int is not -1 (UINT_MAX). But in check_user_data2.c we should
555 * assume that unless unknown_u32 is user data, it's probably less than
556 * INT_MAX.
557 *
558 */
559
560 type = get_type(expr);
561 if (!type_unsigned(type))
562 return;
563
564 /*
565 * Assume if (user < trusted) { ... because I am lazy and because this
566 * is the correct way to write code.
567 */
568 if (!get_user_rl(expr->left, &left))
569 return;
570 if (get_user_rl(expr->right, &right))
571 return;
572
573 if (!sval_is_negative(rl_min(left)))
574 return;
575 min = rl_min(left);
576 minus_one.type = rl_type(left);
577 minus_one.value = -1;
578 non_negative = remove_range(left, min, minus_one);
579
580 switch (expr->op) {
581 case '<':
582 case SPECIAL_UNSIGNED_LT:
583 case SPECIAL_LTE:
584 case SPECIAL_UNSIGNED_LTE:
585 set_true_false_states_expr(my_id, expr->left,
586 alloc_estate_rl(non_negative), NULL);
587 break;
588 case '>':
589 case SPECIAL_UNSIGNED_GT:
590 case SPECIAL_GTE:
591 case SPECIAL_UNSIGNED_GTE:
592 set_true_false_states_expr(my_id, expr->left,
593 NULL, alloc_estate_rl(non_negative));
594 break;
595 }
596 }
597
598 static void match_condition(struct expression *expr)
599 {
600 if (expr->type != EXPR_COMPARE)
601 return;
602
603 if (expr->op == SPECIAL_EQUAL ||
604 expr->op == SPECIAL_NOTEQUAL) {
605 handle_eq_noteq(expr);
606 return;
607 }
608
609 handle_unsigned_lt_gt(expr);
610 }
611
612 static void match_user_assign_function(const char *fn, struct expression *expr, void *unused)
613 {
614 tag_as_user_data(expr->left);
615 set_points_to_user_data(expr->left);
616 }
617
618 static void match_returns_user_rl(const char *fn, struct expression *expr, void *unused)
619 {
620 func_gets_user_data = true;
621 }
622
623 static int get_user_macro_rl(struct expression *expr, struct range_list **rl)
624 {
625 struct expression *parent;
626 char *macro;
627
628 if (!expr)
629 return 0;
630
631 macro = get_macro_name(expr->pos);
632 if (!macro)
633 return 0;
634
635 /* handle ntohl(foo[i]) where "i" is trusted */
636 parent = expr_get_parent_expr(expr);
637 while (parent && parent->type != EXPR_BINOP)
638 parent = expr_get_parent_expr(parent);
639 if (parent && parent->type == EXPR_BINOP) {
640 char *parent_macro = get_macro_name(parent->pos);
641
642 if (parent_macro && strcmp(macro, parent_macro) == 0)
643 return 0;
644 }
645
646 if (strcmp(macro, "ntohl") == 0) {
647 *rl = alloc_whole_rl(&uint_ctype);
648 return 1;
649 }
650 if (strcmp(macro, "ntohs") == 0) {
651 *rl = alloc_whole_rl(&ushort_ctype);
652 return 1;
653 }
654 return 0;
655 }
656
657 struct db_info {
658 struct range_list *rl;
659 struct expression *call;
660 };
661 static int returned_rl_callback(void *_info, int argc, char **argv, char **azColName)
662 {
663 struct db_info *db_info = _info;
664 struct range_list *rl;
665 char *return_ranges = argv[0];
666 char *user_ranges = argv[1];
667 struct expression *arg;
668 int comparison;
669
670 if (argc != 2)
671 return 0;
672
673 call_results_to_rl(db_info->call, get_type(db_info->call), user_ranges, &rl);
674 if (str_to_comparison_arg(return_ranges, db_info->call, &comparison, &arg) &&
675 comparison == SPECIAL_EQUAL) {
676 struct range_list *orig_rl;
677
678 if (!get_user_rl(arg, &orig_rl))
679 return 0;
680 rl = rl_intersection(rl, orig_rl);
681 if (!rl)
682 return 0;
683 }
684 db_info->rl = rl_union(db_info->rl, rl);
685
686 return 0;
687 }
688
689 static int has_user_data(struct symbol *sym)
690 {
691 struct sm_state *tmp;
692
693 FOR_EACH_MY_SM(my_id, __get_cur_stree(), tmp) {
694 if (tmp->sym == sym)
695 return 1;
696 } END_FOR_EACH_SM(tmp);
697 return 0;
698 }
699
700 static int we_pass_user_data(struct expression *call)
701 {
702 struct expression *arg;
703 struct symbol *sym;
704
705 FOR_EACH_PTR(call->args, arg) {
706 sym = expr_to_sym(arg);
707 if (!sym)
708 continue;
709 if (has_user_data(sym))
710 return 1;
711 } END_FOR_EACH_PTR(arg);
712
713 return 0;
714 }
715
716 static int db_returned_user_rl(struct expression *call, struct range_list **rl)
717 {
718 struct db_info db_info = {};
719
720 /* for function pointers assume everything is used */
721 if (call->fn->type != EXPR_SYMBOL)
722 return 0;
723 if (is_fake_call(call))
724 return 0;
725
726 db_info.call = call;
727 run_sql(&returned_rl_callback, &db_info,
728 "select return, value from return_states where %s and type = %d and parameter = -1 and key = '$';",
729 get_static_filter(call->fn->symbol), USER_DATA3_SET);
730 if (db_info.rl) {
731 func_gets_user_data = true;
732 *rl = db_info.rl;
733 return 1;
734 }
735
736 run_sql(&returned_rl_callback, &db_info,
737 "select return, value from return_states where %s and type = %d and parameter = -1 and key = '$';",
738 get_static_filter(call->fn->symbol), USER_DATA3);
739 if (db_info.rl) {
740 if (!we_pass_user_data(call))
741 return 0;
742 *rl = db_info.rl;
743 return 1;
744 }
745
746 return 0;
747 }
748
749 static int user_data_flag;
750 static int no_user_data_flag;
751 static struct range_list *var_user_rl(struct expression *expr)
752 {
753 struct smatch_state *state;
754 struct range_list *rl;
755 struct range_list *absolute_rl;
756
757 if (expr->type == EXPR_BINOP && expr->op == '%') {
758 struct range_list *left, *right;
759
760 if (!get_user_rl(expr->right, &right))
761 return NULL;
762 get_absolute_rl(expr->left, &left);
763 rl = rl_binop(left, '%', right);
764 goto found;
765 }
766
767 if (!option_spammy && expr->type == EXPR_BINOP && expr->op == '/') {
768 struct range_list *left = NULL;
769 struct range_list *right = NULL;
770 struct range_list *abs_right;
771
772 /*
773 * The specific bug I'm dealing with is:
774 *
775 * foo = capped_user / unknown;
776 *
777 * Instead of just saying foo is now entirely user_rl we should
778 * probably say instead that it is not at all user data.
779 *
780 */
781
782 get_user_rl(expr->left, &left);
783 get_user_rl(expr->right, &right);
784 get_absolute_rl(expr->right, &abs_right);
785
786 if (left && !right) {
787 rl = rl_binop(left, '/', abs_right);
788 if (sval_cmp(rl_max(left), rl_max(rl)) < 0)
789 no_user_data_flag = 1;
790 }
791
792 return NULL;
793 }
794
795 if (get_rl_from_function(expr, &rl))
796 goto found;
797
798 if (get_user_macro_rl(expr, &rl))
799 goto found;
800
801 if (comes_from_skb_data(expr)) {
802 rl = alloc_whole_rl(get_type(expr));
803 goto found;
804 }
805
806 state = get_state_expr(my_id, expr);
807 if (state && estate_rl(state)) {
808 rl = estate_rl(state);
809 goto found;
810 }
811
812 if (expr->type == EXPR_CALL && db_returned_user_rl(expr, &rl))
813 goto found;
814
815 if (is_array(expr)) {
816 struct expression *array = get_array_base(expr);
817
818 if (!get_state_expr(my_id, array)) {
819 no_user_data_flag = 1;
820 return NULL;
821 }
822 }
823
824 if (expr->type == EXPR_PREOP && expr->op == '*' &&
825 is_user_rl(expr->unop)) {
826 rl = var_to_absolute_rl(expr);
827 goto found;
828 }
829
830 return NULL;
831 found:
832 user_data_flag = 1;
833 absolute_rl = var_to_absolute_rl(expr);
834 return clone_rl(rl_intersection(rl, absolute_rl));
835 }
836
837 int get_user_rl(struct expression *expr, struct range_list **rl)
838 {
839 user_data_flag = 0;
840 no_user_data_flag = 0;
841 custom_get_absolute_rl(expr, &var_user_rl, rl);
842 if (!user_data_flag || no_user_data_flag)
843 *rl = NULL;
844
845 return !!*rl;
846 }
847
848 int get_user_rl_spammy(struct expression *expr, struct range_list **rl)
849 {
850 int ret;
851
852 option_spammy++;
853 ret = get_user_rl(expr, rl);
854 option_spammy--;
855
856 return ret;
857 }
858
859 int is_user_rl(struct expression *expr)
860 {
861 struct range_list *tmp;
862
863 return get_user_rl_spammy(expr, &tmp);
864 }
865
866 int get_user_rl_var_sym(const char *name, struct symbol *sym, struct range_list **rl)
867 {
868 struct smatch_state *state;
869
870 state = get_state(my_id, name, sym);
871 if (state && estate_rl(state)) {
872 *rl = estate_rl(state);
873 return 1;
874 }
875 return 0;
876 }
877
878 static void match_call_info(struct expression *expr)
879 {
880 struct range_list *rl;
881 struct expression *arg;
882 int i = 0;
883
884 i = -1;
885 FOR_EACH_PTR(expr->args, arg) {
886 i++;
887
888 if (!get_user_rl(arg, &rl))
889 continue;
890
891 sql_insert_caller_info(expr, USER_DATA3, i, "$", show_rl(rl));
892 } END_FOR_EACH_PTR(arg);
893 }
894
895 static int is_struct_ptr(struct symbol *sym)
896 {
897 struct symbol *type;
898
899 if (!sym)
900 return 0;
901 type = get_real_base_type(sym);
902 if (!type || type->type != SYM_PTR)
903 return 0;
904 type = get_real_base_type(type);
905 if (!type || type->type != SYM_STRUCT)
906 return 0;
907 return 1;
908 }
909
910 static void struct_member_callback(struct expression *call, int param, char *printed_name, struct sm_state *sm)
911 {
912 struct smatch_state *state;
913 struct range_list *rl;
914
915 if (strcmp(sm->state->name, "") == 0)
916 return;
917
918 if (strcmp(printed_name, "*$") == 0 &&
919 is_struct_ptr(sm->sym))
920 return;
921
922 state = get_state(SMATCH_EXTRA, sm->name, sm->sym);
923 if (!state || !estate_rl(state))
924 rl = estate_rl(sm->state);
925 else
926 rl = rl_intersection(estate_rl(sm->state), estate_rl(state));
927
928 sql_insert_caller_info(call, USER_DATA3, param, printed_name, show_rl(rl));
929 }
930
931 static void set_param_user_data(const char *name, struct symbol *sym, char *key, char *value)
932 {
933 struct range_list *rl = NULL;
934 struct smatch_state *state;
935 struct symbol *type;
936 char fullname[256];
937
938 if (strcmp(key, "*$") == 0)
939 snprintf(fullname, sizeof(fullname), "*%s", name);
940 else if (strncmp(key, "$", 1) == 0)
941 snprintf(fullname, 256, "%s%s", name, key + 1);
942 else
943 return;
944
945 type = get_member_type_from_key(symbol_expression(sym), key);
946
947 /* if the caller passes a void pointer with user data */
948 if (strcmp(key, "*$") == 0 && type && type != &void_ctype) {
949 struct expression *expr = symbol_expression(sym);
950
951 tag_as_user_data(expr);
952 set_points_to_user_data(expr);
953 return;
954 }
955 str_to_rl(type, value, &rl);
956 state = alloc_estate_rl(rl);
957 set_state(my_id, fullname, sym, state);
958 }
959
960 static void set_called(const char *name, struct symbol *sym, char *key, char *value)
961 {
962 set_state(my_call_id, "this_function", NULL, &called);
963 }
964
965 static void match_syscall_definition(struct symbol *sym)
966 {
967 struct symbol *arg;
968 char *macro;
969 char *name;
970 int is_syscall = 0;
971
972 macro = get_macro_name(sym->pos);
973 if (macro &&
974 (strncmp("SYSCALL_DEFINE", macro, strlen("SYSCALL_DEFINE")) == 0 ||
975 strncmp("COMPAT_SYSCALL_DEFINE", macro, strlen("COMPAT_SYSCALL_DEFINE")) == 0))
976 is_syscall = 1;
977
978 name = get_function();
979 if (!option_no_db && get_state(my_call_id, "this_function", NULL) != &called) {
980 if (name && strncmp(name, "sys_", 4) == 0)
981 is_syscall = 1;
982 }
983
984 if (name && strncmp(name, "compat_sys_", 11) == 0)
985 is_syscall = 1;
986
987 if (!is_syscall)
988 return;
989
990 FOR_EACH_PTR(sym->ctype.base_type->arguments, arg) {
991 set_state(my_id, arg->ident->name, arg, alloc_estate_whole(get_real_base_type(arg)));
992 } END_FOR_EACH_PTR(arg);
993 }
994
995 static void set_to_user_data(struct expression *expr, char *key, char *value)
996 {
997 char *name;
998 struct symbol *sym;
999 struct symbol *type;
1000 struct range_list *rl = NULL;
1001
1002 type = get_member_type_from_key(expr, key);
1003 name = get_variable_from_key(expr, key, &sym);
1004 if (!name || !sym)
1005 goto free;
1006
1007 call_results_to_rl(expr, type, value, &rl);
1008
1009 set_state(my_id, name, sym, alloc_estate_rl(rl));
1010 free:
1011 free_string(name);
1012
1013 }
1014
1015 static void returns_param_user_data(struct expression *expr, int param, char *key, char *value)
1016 {
1017 struct expression *arg;
1018 struct expression *call;
1019
1020 call = expr;
1021 while (call->type == EXPR_ASSIGNMENT)
1022 call = strip_expr(call->right);
1023 if (call->type != EXPR_CALL)
1024 return;
1025
1026 if (!we_pass_user_data(call))
1027 return;
1028
1029 if (param == -1) {
1030 if (expr->type != EXPR_ASSIGNMENT)
1031 return;
1032 set_to_user_data(expr->left, key, value);
1033 return;
1034 }
1035
1036 arg = get_argument_from_call_expr(call->args, param);
1037 if (!arg)
1038 return;
1039 set_to_user_data(arg, key, value);
1040 }
1041
1042 static void returns_param_user_data_set(struct expression *expr, int param, char *key, char *value)
1043 {
1044 struct expression *arg;
1045
1046 func_gets_user_data = true;
1047
1048 if (param == -1) {
1049 if (expr->type != EXPR_ASSIGNMENT)
1050 return;
1051 if (strcmp(key, "*$") == 0) {
1052 set_points_to_user_data(expr->left);
1053 tag_as_user_data(expr->left);
1054 } else {
1055 set_to_user_data(expr->left, key, value);
1056 }
1057 return;
1058 }
1059
1060 while (expr->type == EXPR_ASSIGNMENT)
1061 expr = strip_expr(expr->right);
1062 if (expr->type != EXPR_CALL)
1063 return;
1064
1065 arg = get_argument_from_call_expr(expr->args, param);
1066 if (!arg)
1067 return;
1068 set_to_user_data(arg, key, value);
1069 }
1070
1071 static int has_empty_state(struct sm_state *sm)
1072 {
1073 struct sm_state *tmp;
1074
1075 FOR_EACH_PTR(sm->possible, tmp) {
1076 if (!estate_rl(tmp->state))
1077 return 1;
1078 } END_FOR_EACH_PTR(tmp);
1079
1080 return 0;
1081 }
1082
1083 static void param_set_to_user_data(int return_id, char *return_ranges, struct expression *expr)
1084 {
1085 struct sm_state *sm;
1086 struct smatch_state *start_state;
1087 struct range_list *rl;
1088 int param;
1089 char *return_str;
1090 const char *param_name;
1091 struct symbol *ret_sym;
1092 bool return_found = false;
1093
1094 expr = strip_expr(expr);
1095 return_str = expr_to_str(expr);
1096 ret_sym = expr_to_sym(expr);
1097
1098 FOR_EACH_MY_SM(my_id, __get_cur_stree(), sm) {
1099 if (has_empty_state(sm))
1100 continue;
1101
1102 param = get_param_num_from_sym(sm->sym);
1103 if (param < 0)
1104 continue;
1105
1106 /* The logic here was that if we were passed in a user data then
1107 * we don't record that. It's like the difference between
1108 * param_filter and param_set. When I think about it, I'm not
1109 * sure it actually works. It's probably harmless because we
1110 * checked earlier that we're not returning a parameter...
1111 * Let's mark this as a TODO.
1112 */
1113 start_state = get_state_stree(start_states, my_id, sm->name, sm->sym);
1114 if (start_state && rl_equiv(estate_rl(sm->state), estate_rl(start_state)))
1115 continue;
1116
1117 param_name = get_param_name(sm);
1118 if (!param_name)
1119 continue;
1120 if (strcmp(param_name, "$") == 0) /* The -1 param is handled after the loop */
1121 continue;
1122
1123 sql_insert_return_states(return_id, return_ranges,
1124 func_gets_user_data ? USER_DATA3_SET : USER_DATA3,
1125 param, param_name, show_rl(estate_rl(sm->state)));
1126 } END_FOR_EACH_SM(sm);
1127
1128 if (points_to_user_data(expr)) {
1129 sql_insert_return_states(return_id, return_ranges,
1130 (is_skb_data(expr) || !func_gets_user_data) ?
1131 USER_DATA3_SET : USER_DATA3,
1132 -1, "*$", "");
1133 goto free_string;
1134 }
1135
1136
1137 FOR_EACH_MY_SM(my_id, __get_cur_stree(), sm) {
1138 if (!ret_sym)
1139 break;
1140 if (ret_sym != sm->sym)
1141 continue;
1142
1143 param_name = state_name_to_param_name(sm->name, return_str);
1144 if (!param_name)
1145 continue;
1146 if (strcmp(param_name, "$") == 0)
1147 return_found = true;
1148 sql_insert_return_states(return_id, return_ranges,
1149 func_gets_user_data ? USER_DATA3_SET : USER_DATA3,
1150 -1, param_name, show_rl(estate_rl(sm->state)));
1151 } END_FOR_EACH_SM(sm);
1152
1153
1154 if (!return_found && get_user_rl(expr, &rl)) {
1155 sql_insert_return_states(return_id, return_ranges,
1156 func_gets_user_data ? USER_DATA3_SET : USER_DATA3,
1157 -1, "$", show_rl(rl));
1158 goto free_string;
1159 }
1160
1161 free_string:
1162 free_string(return_str);
1163 }
1164
1165 static struct int_stack *gets_data_stack;
1166 static void match_function_def(struct symbol *sym)
1167 {
1168 func_gets_user_data = false;
1169 }
1170
1171 static void match_inline_start(struct expression *expr)
1172 {
1173 push_int(&gets_data_stack, func_gets_user_data);
1174 }
1175
1176 static void match_inline_end(struct expression *expr)
1177 {
1178 func_gets_user_data = pop_int(&gets_data_stack);
1179 }
1180
1181 void check_user_data2(int id)
1182 {
1183 int i;
1184
1185 my_id = id;
1186
1187 if (option_project != PROJ_KERNEL)
1188 return;
1189
1190 add_hook(&match_function_def, FUNC_DEF_HOOK);
1191 add_hook(&match_inline_start, INLINE_FN_START);
1192 add_hook(&match_inline_end, INLINE_FN_END);
1193
1194 add_hook(&save_start_states, AFTER_DEF_HOOK);
1195 add_hook(&free_start_states, AFTER_FUNC_HOOK);
1196 add_hook(&match_save_states, INLINE_FN_START);
1197 add_hook(&match_restore_states, INLINE_FN_END);
1198
1199 add_unmatched_state_hook(my_id, &empty_state);
1200 add_extra_nomod_hook(&extra_nomod_hook);
1201 add_pre_merge_hook(my_id, &pre_merge_hook);
1202 add_merge_hook(my_id, &merge_estates);
1203
1204 add_function_hook("copy_from_user", &match_user_copy, INT_PTR(0));
1205 add_function_hook("__copy_from_user", &match_user_copy, INT_PTR(0));
1206 add_function_hook("memcpy_fromiovec", &match_user_copy, INT_PTR(0));
1207 for (i = 0; i < ARRAY_SIZE(kstr_funcs); i++)
1208 add_function_hook(kstr_funcs[i], &match_user_copy, INT_PTR(2));
1209 add_function_hook("usb_control_msg", &match_user_copy, INT_PTR(6));
1210
1211 for (i = 0; i < ARRAY_SIZE(returns_user_data); i++) {
1212 add_function_assign_hook(returns_user_data[i], &match_user_assign_function, NULL);
1213 add_function_hook(returns_user_data[i], &match_returns_user_rl, NULL);
1214 }
1215
1216 add_function_hook("sscanf", &match_sscanf, NULL);
1217
1218 add_hook(&match_syscall_definition, AFTER_DEF_HOOK);
1219
1220 add_hook(&match_assign, ASSIGNMENT_HOOK);
1221 add_hook(&match_condition, CONDITION_HOOK);
1222
1223 add_hook(&match_call_info, FUNCTION_CALL_HOOK);
1224 add_member_info_callback(my_id, struct_member_callback);
1225 select_caller_info_hook(set_param_user_data, USER_DATA3);
1226 select_return_states_hook(USER_DATA3, &returns_param_user_data);
1227 select_return_states_hook(USER_DATA3_SET, &returns_param_user_data_set);
1228 add_split_return_callback(&param_set_to_user_data);
1229 }
1230
1231 void check_user_data3(int id)
1232 {
1233 my_call_id = id;
1234
1235 if (option_project != PROJ_KERNEL)
1236 return;
1237 select_caller_info_hook(set_called, INTERNAL);
1238 }
1239
Static analysis for C