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db: use the load_strings_from_file() helper function
[smatch.git] / smatch_kernel_user_data.c
blob348ff7e4762410a0f972a0506f9d0172c99af57b
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 unsigned long 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",
49 };
50
51 static struct stree *start_states;
52 static void save_start_states(struct statement *stmt)
53 {
54 start_states = clone_stree(__get_cur_stree());
55 }
56
57 static void free_start_states(void)
58 {
59 free_stree(&start_states);
60 }
61
62 static struct smatch_state *empty_state(struct sm_state *sm)
63 {
64 return alloc_estate_empty();
65 }
66
67 static struct smatch_state *new_state(struct symbol *type)
68 {
69 struct smatch_state *state;
70
71 if (!type || type_is_ptr(type))
72 return NULL;
73
74 state = alloc_estate_whole(type);
75 estate_set_new(state);
76 return state;
77 }
78
79 static void pre_merge_hook(struct sm_state *cur, struct sm_state *other)
80 {
81 struct smatch_state *user = cur->state;
82 struct smatch_state *extra;
83 struct smatch_state *state;
84 struct range_list *rl;
85
86 extra = __get_state(SMATCH_EXTRA, cur->name, cur->sym);
87 if (!extra)
88 return;
89 rl = rl_intersection(estate_rl(user), estate_rl(extra));
90 state = alloc_estate_rl(clone_rl(rl));
91 if (estate_capped(user) || is_capped_var_sym(cur->name, cur->sym))
92 estate_set_capped(state);
93 if (estate_treat_untagged(user))
94 estate_set_treat_untagged(state);
95 if (estates_equiv(state, cur->state))
96 return;
97 set_state(my_id, cur->name, cur->sym, state);
98 }
99
100 static void extra_nomod_hook(const char *name, struct symbol *sym, struct expression *expr, struct smatch_state *state)
101 {
102 struct smatch_state *user, *new;
103 struct range_list *rl;
104
105 user = __get_state(my_id, name, sym);
106 if (!user)
107 return;
108 rl = rl_intersection(estate_rl(user), estate_rl(state));
109 if (rl_equiv(rl, estate_rl(user)))
110 return;
111 new = alloc_estate_rl(rl);
112 if (estate_capped(user))
113 estate_set_capped(new);
114 if (estate_treat_untagged(user))
115 estate_set_treat_untagged(new);
116 set_state(my_id, name, sym, new);
117 }
118
119 static bool user_rl_known(struct expression *expr)
120 {
121 struct range_list *rl;
122 sval_t close_to_max;
123
124 if (!get_user_rl(expr, &rl))
125 return true;
126
127 close_to_max = sval_type_max(rl_type(rl));
128 close_to_max.value -= 100;
129
130 if (sval_cmp(rl_max(rl), close_to_max) >= 0)
131 return false;
132 return true;
133 }
134
135 static bool is_array_index_mask_nospec(struct expression *expr)
136 {
137 struct expression *orig;
138
139 orig = get_assigned_expr(expr);
140 if (!orig || orig->type != EXPR_CALL)
141 return false;
142 return sym_name_is("array_index_mask_nospec", orig->fn);
143 }
144
145 static bool binop_capped(struct expression *expr)
146 {
147 struct range_list *left_rl;
148 int comparison;
149 sval_t sval;
150
151 if (expr->op == '-' && get_user_rl(expr->left, &left_rl)) {
152 if (user_rl_capped(expr->left))
153 return true;
154 comparison = get_comparison(expr->left, expr->right);
155 if (comparison && show_special(comparison)[0] == '>')
156 return true;
157 return false;
158 }
159
160 if (expr->op == '&' || expr->op == '%') {
161 bool left_user, left_capped, right_user, right_capped;
162
163 if (!get_value(expr->right, &sval) && is_capped(expr->right))
164 return true;
165 if (is_array_index_mask_nospec(expr->right))
166 return true;
167 if (is_capped(expr->left))
168 return true;
169 left_user = is_user_rl(expr->left);
170 right_user = is_user_rl(expr->right);
171 if (!left_user && !right_user)
172 return true;
173
174 left_capped = user_rl_capped(expr->left);
175 right_capped = user_rl_capped(expr->right);
176
177 if (left_user && left_capped) {
178 if (!right_user)
179 return true;
180 if (right_user && right_capped)
181 return true;
182 return false;
183 }
184 if (right_user && right_capped) {
185 if (!left_user)
186 return true;
187 return false;
188 }
189 return false;
190 }
191
192 /*
193 * Generally "capped" means that we capped it to an unknown value.
194 * This is useful because if Smatch doesn't know what the value is then
195 * we have to trust that it is correct. But if we known cap value is
196 * 100 then we can check if 100 is correct and complain if it's wrong.
197 *
198 * So then the problem is with BINOP when we take a capped variable
199 * plus a user variable which is clamped to a known range (uncapped)
200 * the result should be capped.
201 */
202 if ((user_rl_capped(expr->left) || user_rl_known(expr->left)) &&
203 (user_rl_capped(expr->right) || user_rl_known(expr->right)))
204 return true;
205
206 return false;
207 }
208
209 bool user_rl_capped(struct expression *expr)
210 {
211 struct smatch_state *state;
212 struct range_list *rl;
213 sval_t sval;
214
215 expr = strip_expr(expr);
216 if (!expr)
217 return false;
218 if (get_value(expr, &sval))
219 return true;
220 if (expr->type == EXPR_BINOP)
221 return binop_capped(expr);
222 if ((expr->type == EXPR_PREOP || expr->type == EXPR_POSTOP) &&
223 (expr->op == SPECIAL_INCREMENT || expr->op == SPECIAL_DECREMENT))
224 return user_rl_capped(expr->unop);
225 state = get_state_expr(my_id, expr);
226 if (state)
227 return estate_capped(state);
228
229 if (!get_user_rl(expr, &rl)) {
230 /*
231 * The non user data parts of a binop are capped and
232 * also empty user rl states are capped.
233 */
234 return true;
235 }
236
237 if (rl_to_sval(rl, &sval))
238 return true;
239
240 return false; /* uncapped user data */
241 }
242
243 bool user_rl_treat_untagged(struct expression *expr)
244 {
245 struct smatch_state *state;
246 struct range_list *rl;
247 sval_t sval;
248
249 expr = strip_expr(expr);
250 if (!expr)
251 return false;
252 if (get_value(expr, &sval))
253 return true;
254
255 state = get_state_expr(my_id, expr);
256 if (state)
257 return estate_treat_untagged(state);
258
259 if (get_user_rl(expr, &rl))
260 return false; /* uncapped user data */
261
262 return true; /* not actually user data */
263 }
264
265 static void tag_inner_struct_members(struct expression *expr, struct symbol *member)
266 {
267 struct expression *edge_member;
268 struct symbol *base = get_real_base_type(member);
269 struct symbol *tmp;
270
271 if (member->ident)
272 expr = member_expression(expr, '.', member->ident);
273
274 FOR_EACH_PTR(base->symbol_list, tmp) {
275 struct symbol *type;
276
277 type = get_real_base_type(tmp);
278 if (!type)
279 continue;
280
281 if (type->type == SYM_UNION || type->type == SYM_STRUCT) {
282 tag_inner_struct_members(expr, tmp);
283 continue;
284 }
285
286 if (!tmp->ident)
287 continue;
288
289 edge_member = member_expression(expr, '.', tmp->ident);
290 set_state_expr(my_id, edge_member, new_state(type));
291 } END_FOR_EACH_PTR(tmp);
292 }
293
294 void __set_user_string(struct expression *expr);
295 static void tag_struct_members(struct symbol *type, struct expression *expr)
296 {
297 struct symbol *tmp;
298 struct expression *member;
299 int op = '*';
300
301 if (expr->type == EXPR_PREOP && expr->op == '&') {
302 expr = strip_expr(expr->unop);
303 op = '.';
304 }
305
306 FOR_EACH_PTR(type->symbol_list, tmp) {
307 type = get_real_base_type(tmp);
308 if (!type)
309 continue;
310
311 if (type->type == SYM_UNION || type->type == SYM_STRUCT) {
312 tag_inner_struct_members(expr, tmp);
313 continue;
314 }
315
316 if (!tmp->ident)
317 continue;
318
319 member = member_expression(expr, op, tmp->ident);
320 if (type->type == SYM_ARRAY) {
321 set_points_to_user_data(member);
322 } else {
323 set_state_expr(my_id, member, new_state(get_type(member)));
324 }
325 } END_FOR_EACH_PTR(tmp);
326 }
327
328 static void tag_base_type(struct expression *expr)
329 {
330 if (expr->type == EXPR_PREOP && expr->op == '&')
331 expr = strip_expr(expr->unop);
332 else
333 expr = deref_expression(expr);
334 set_state_expr(my_id, expr, new_state(get_type(expr)));
335 }
336
337 static void tag_as_user_data(struct expression *expr)
338 {
339 struct symbol *type;
340
341 expr = strip_expr(expr);
342
343 type = get_type(expr);
344 if (!type || type->type != SYM_PTR)
345 return;
346 type = get_real_base_type(type);
347 if (!type)
348 return;
349 if (type == &void_ctype) {
350 set_state_expr(my_id, deref_expression(expr), new_state(&ulong_ctype));
351 return;
352 }
353 if (type->type == SYM_BASETYPE) {
354 if (expr->type != EXPR_PREOP && expr->op != '&')
355 set_points_to_user_data(expr);
356 tag_base_type(expr);
357 return;
358 }
359 if (type->type == SYM_STRUCT || type->type == SYM_UNION) {
360 if (expr->type != EXPR_PREOP || expr->op != '&')
361 expr = deref_expression(expr);
362 else
363 set_state_expr(my_id, deref_expression(expr), new_state(&ulong_ctype));
364 tag_struct_members(type, expr);
365 }
366 }
367
368 static void match_user_copy(const char *fn, struct expression *expr, void *_param)
369 {
370 int param = PTR_INT(_param);
371 struct expression *dest;
372
373 func_gets_user_data = true;
374
375 dest = get_argument_from_call_expr(expr->args, param);
376 dest = strip_expr(dest);
377 if (!dest)
378 return;
379 tag_as_user_data(dest);
380 }
381
382 static int is_dev_attr_name(struct expression *expr)
383 {
384 char *name;
385 int ret = 0;
386
387 name = expr_to_str(expr);
388 if (!name)
389 return 0;
390 if (strstr(name, "->attr.name"))
391 ret = 1;
392 free_string(name);
393 return ret;
394 }
395
396 static int ends_in_n(struct expression *expr)
397 {
398 struct string *str;
399
400 if (!expr)
401 return 0;
402 if (expr->type != EXPR_STRING || !expr->string)
403 return 0;
404
405 str = expr->string;
406 if (str->length < 3)
407 return 0;
408
409 if (str->data[str->length - 3] == '%' &&
410 str->data[str->length - 2] == 'n')
411 return 1;
412 return 0;
413 }
414
415 static void match_sscanf(const char *fn, struct expression *expr, void *unused)
416 {
417 struct expression *str, *format, *arg;
418 int i, last;
419
420 func_gets_user_data = true;
421
422 str = get_argument_from_call_expr(expr->args, 0);
423 if (is_dev_attr_name(str))
424 return;
425
426 format = get_argument_from_call_expr(expr->args, 1);
427 if (is_dev_attr_name(format))
428 return;
429
430 last = ptr_list_size((struct ptr_list *)expr->args) - 1;
431
432 i = -1;
433 FOR_EACH_PTR(expr->args, arg) {
434 i++;
435 if (i < 2)
436 continue;
437 if (i == last && ends_in_n(format))
438 continue;
439 tag_as_user_data(arg);
440 } END_FOR_EACH_PTR(arg);
441 }
442
443 static int get_rl_from_function(struct expression *expr, struct range_list **rl)
444 {
445 int i;
446
447 if (expr->type != EXPR_CALL || expr->fn->type != EXPR_SYMBOL ||
448 !expr->fn->symbol_name || !expr->fn->symbol_name->name)
449 return 0;
450
451 for (i = 0; i < ARRAY_SIZE(returns_user_data); i++) {
452 if (strcmp(expr->fn->symbol_name->name, returns_user_data[i]) == 0) {
453 *rl = alloc_whole_rl(get_type(expr));
454 return 1;
455 }
456 }
457 return 0;
458 }
459
460 static int comes_from_skb_data(struct expression *expr)
461 {
462 expr = strip_expr(expr);
463 if (!expr || expr->type != EXPR_PREOP || expr->op != '*')
464 return 0;
465
466 expr = strip_expr(expr->unop);
467 if (!expr)
468 return 0;
469 if (expr->type == EXPR_BINOP && expr->op == '+')
470 expr = strip_expr(expr->left);
471
472 return is_skb_data(expr);
473 }
474
475 static int handle_get_user(struct expression *expr)
476 {
477 char *name;
478 int ret = 0;
479
480 name = get_macro_name(expr->pos);
481 if (!name || strcmp(name, "get_user") != 0)
482 return 0;
483
484 name = expr_to_var(expr->right);
485 if (!name || (strcmp(name, "__val_gu") != 0 && strcmp(name, "__gu_val") != 0))
486 goto free;
487 set_state_expr(my_id, expr->left, new_state(get_type(expr->left)));
488 ret = 1;
489 free:
490 free_string(name);
491 return ret;
492 }
493
494 static bool state_is_new(struct expression *expr)
495 {
496 struct smatch_state *state;
497
498 state = get_state_expr(my_id, expr);
499 if (estate_new(state))
500 return true;
501
502 if (expr->type == EXPR_BINOP) {
503 if (state_is_new(expr->left))
504 return true;
505 if (state_is_new(expr->right))
506 return true;
507 }
508 return false;
509 }
510
511 static bool handle_op_assign(struct expression *expr)
512 {
513 struct expression *binop_expr;
514 struct smatch_state *state;
515 struct range_list *rl;
516
517 switch (expr->op) {
518 case SPECIAL_ADD_ASSIGN:
519 case SPECIAL_SUB_ASSIGN:
520 case SPECIAL_AND_ASSIGN:
521 case SPECIAL_MOD_ASSIGN:
522 case SPECIAL_SHL_ASSIGN:
523 case SPECIAL_SHR_ASSIGN:
524 case SPECIAL_OR_ASSIGN:
525 case SPECIAL_XOR_ASSIGN:
526 case SPECIAL_MUL_ASSIGN:
527 case SPECIAL_DIV_ASSIGN:
528 binop_expr = binop_expression(expr->left,
529 op_remove_assign(expr->op),
530 expr->right);
531 if (!get_user_rl(binop_expr, &rl))
532 return true;
533
534 rl = cast_rl(get_type(expr->left), rl);
535 state = alloc_estate_rl(rl);
536 if (user_rl_capped(binop_expr))
537 estate_set_capped(state);
538 if (user_rl_treat_untagged(expr->left))
539 estate_set_treat_untagged(state);
540 if (state_is_new(binop_expr))
541 estate_set_new(state);
542 set_state_expr(my_id, expr->left, state);
543 return true;
544 }
545 return false;
546 }
547
548 static void match_assign(struct expression *expr)
549 {
550 struct symbol *left_type, *right_type;
551 struct range_list *rl;
552 static struct expression *handled;
553 struct smatch_state *state;
554 struct expression *faked;
555 bool is_capped = false;
556 bool is_new = false;
557
558 left_type = get_type(expr->left);
559 if (left_type == &void_ctype)
560 return;
561
562 faked = get_faked_expression();
563
564 /* FIXME: handle fake array assignments frob(&user_array[x]); */
565
566 if (is_fake_call(expr->right) && faked &&
567 faked->type == EXPR_ASSIGNMENT &&
568 points_to_user_data(faked->right)) {
569 if (is_skb_data(faked->right))
570 func_gets_user_data = true;
571 rl = alloc_whole_rl(get_type(expr->left));
572 is_new = true;
573 goto set;
574 }
575
576 if (faked && faked == handled)
577 return;
578 if (is_fake_call(expr->right))
579 goto clear_old_state;
580 if (handle_get_user(expr))
581 return;
582 if (points_to_user_data(expr->right) &&
583 is_struct_ptr(get_type(expr->left))) {
584 handled = expr;
585 // This should be handled by smatch_points_to_user_data.c
586 // set_points_to_user_data(expr->left);
587 }
588
589 if (handle_op_assign(expr))
590 return;
591 if (expr->op != '=')
592 goto clear_old_state;
593
594 /* Handled by DB code */
595 if (expr->right->type == EXPR_CALL || __in_fake_parameter_assign)
596 return;
597
598 if (!get_user_rl(expr->right, &rl))
599 goto clear_old_state;
600 is_capped = user_rl_capped(expr->right);
601 is_new = state_is_new(expr->right);
602
603 set:
604 if (type_is_ptr(left_type)) {
605 right_type = get_type(expr->right);
606 if (right_type && right_type->type == SYM_ARRAY)
607 set_points_to_user_data(expr->left);
608 return;
609 }
610
611 rl = cast_rl(left_type, rl);
612 state = alloc_estate_rl(rl);
613 if (is_new)
614 estate_set_new(state);
615 if (is_capped)
616 estate_set_capped(state);
617 if (user_rl_treat_untagged(expr->right))
618 estate_set_treat_untagged(state);
619
620 set_state_expr(my_id, expr->left, state);
621
622 return;
623
624 clear_old_state:
625
626 /*
627 * HACK ALERT!!! This should be at the start of the function. The
628 * the problem is that handling "pointer = array;" assignments is
629 * handled in this function instead of in kernel_points_to_user_data.c.
630 */
631 if (type_is_ptr(left_type))
632 return;
633
634 if (get_state_expr(my_id, expr->left))
635 set_state_expr(my_id, expr->left, alloc_estate_empty());
636 }
637
638 static void handle_eq_noteq(struct expression *expr)
639 {
640 struct smatch_state *left_orig, *right_orig;
641
642 left_orig = get_state_expr(my_id, expr->left);
643 right_orig = get_state_expr(my_id, expr->right);
644
645 if (!left_orig && !right_orig)
646 return;
647 if (left_orig && right_orig)
648 return;
649
650 if (left_orig) {
651 set_true_false_states_expr(my_id, expr->left,
652 expr->op == SPECIAL_EQUAL ? alloc_estate_empty() : NULL,
653 expr->op == SPECIAL_EQUAL ? NULL : alloc_estate_empty());
654 } else {
655 set_true_false_states_expr(my_id, expr->right,
656 expr->op == SPECIAL_EQUAL ? alloc_estate_empty() : NULL,
657 expr->op == SPECIAL_EQUAL ? NULL : alloc_estate_empty());
658 }
659 }
660
661 static struct range_list *strip_negatives(struct range_list *rl)
662 {
663 sval_t min = rl_min(rl);
664 sval_t minus_one = { .type = rl_type(rl), .value = -1 };
665 sval_t over = { .type = rl_type(rl), .value = INT_MAX + 1ULL };
666 sval_t max = sval_type_max(rl_type(rl));
667
668 if (!rl)
669 return NULL;
670
671 if (type_unsigned(rl_type(rl)) && type_bits(rl_type(rl)) > 31)
672 return remove_range(rl, over, max);
673
674 return remove_range(rl, min, minus_one);
675 }
676
677 static void handle_compare(struct expression *expr)
678 {
679 struct expression *left, *right;
680 struct range_list *left_rl = NULL;
681 struct range_list *right_rl = NULL;
682 struct range_list *user_rl;
683 struct smatch_state *capped_state;
684 struct smatch_state *left_true = NULL;
685 struct smatch_state *left_false = NULL;
686 struct smatch_state *right_true = NULL;
687 struct smatch_state *right_false = NULL;
688 struct symbol *type;
689 sval_t sval;
690
691 left = strip_expr(expr->left);
692 right = strip_expr(expr->right);
693
694 while (left->type == EXPR_ASSIGNMENT)
695 left = strip_expr(left->left);
696
697 /*
698 * Conditions are mostly handled by smatch_extra.c, but there are some
699 * times where the exact values are not known so we can't do that.
700 *
701 * Normally, we might consider using smatch_capped.c to supliment smatch
702 * extra but that doesn't work when we merge unknown uncapped kernel
703 * data with unknown capped user data. The result is uncapped user
704 * data. We need to keep it separate and say that the user data is
705 * capped. In the past, I would have marked this as just regular
706 * kernel data (not user data) but we can't do that these days because
707 * we need to track user data for Spectre.
708 *
709 * The other situation which we have to handle is when we do have an
710 * int and we compare against an unknown unsigned kernel variable. In
711 * that situation we assume that the kernel data is less than INT_MAX.
712 * Otherwise then we get all sorts of array underflow false positives.
713 *
714 */
715
716 /* Handled in smatch_extra.c */
717 if (get_implied_value(left, &sval) ||
718 get_implied_value(right, &sval))
719 return;
720
721 get_user_rl(left, &left_rl);
722 get_user_rl(right, &right_rl);
723
724 /* nothing to do */
725 if (!left_rl && !right_rl)
726 return;
727 /* if both sides are user data that's not a good limit */
728 if (left_rl && right_rl)
729 return;
730
731 if (left_rl)
732 user_rl = left_rl;
733 else
734 user_rl = right_rl;
735
736 type = get_type(expr);
737 if (type_unsigned(type))
738 user_rl = strip_negatives(user_rl);
739 capped_state = alloc_estate_rl(user_rl);
740 estate_set_capped(capped_state);
741
742 switch (expr->op) {
743 case '<':
744 case SPECIAL_UNSIGNED_LT:
745 case SPECIAL_LTE:
746 case SPECIAL_UNSIGNED_LTE:
747 if (left_rl)
748 left_true = capped_state;
749 else
750 right_false = capped_state;
751 break;
752 case '>':
753 case SPECIAL_UNSIGNED_GT:
754 case SPECIAL_GTE:
755 case SPECIAL_UNSIGNED_GTE:
756 if (left_rl)
757 left_false = capped_state;
758 else
759 right_true = capped_state;
760 break;
761 }
762
763 set_true_false_states_expr(my_id, left, left_true, left_false);
764 set_true_false_states_expr(my_id, right, right_true, right_false);
765 }
766
767 static void match_condition(struct expression *expr)
768 {
769 if (expr->type != EXPR_COMPARE)
770 return;
771
772 if (expr->op == SPECIAL_EQUAL ||
773 expr->op == SPECIAL_NOTEQUAL) {
774 handle_eq_noteq(expr);
775 return;
776 }
777
778 handle_compare(expr);
779 }
780
781 static void match_returns_user_rl(const char *fn, struct expression *expr, void *unused)
782 {
783 func_gets_user_data = true;
784 }
785
786 static int get_user_macro_rl(struct expression *expr, struct range_list **rl)
787 {
788 struct expression *parent;
789 char *macro;
790
791 if (!expr)
792 return 0;
793
794 macro = get_macro_name(expr->pos);
795 if (!macro)
796 return 0;
797
798 /* handle ntohl(foo[i]) where "i" is trusted */
799 parent = expr_get_parent_expr(expr);
800 while (parent && parent->type != EXPR_BINOP)
801 parent = expr_get_parent_expr(parent);
802 if (parent && parent->type == EXPR_BINOP) {
803 char *parent_macro = get_macro_name(parent->pos);
804
805 if (parent_macro && strcmp(macro, parent_macro) == 0)
806 return 0;
807 }
808
809 if (strcmp(macro, "ntohl") == 0) {
810 *rl = alloc_whole_rl(&uint_ctype);
811 return 1;
812 }
813 if (strcmp(macro, "ntohs") == 0) {
814 *rl = alloc_whole_rl(&ushort_ctype);
815 return 1;
816 }
817 return 0;
818 }
819
820 static int has_user_data(struct symbol *sym)
821 {
822 struct sm_state *tmp;
823
824 FOR_EACH_MY_SM(my_id, __get_cur_stree(), tmp) {
825 if (tmp->sym == sym)
826 return 1;
827 } END_FOR_EACH_SM(tmp);
828 return 0;
829 }
830
831 bool we_pass_user_data(struct expression *call)
832 {
833 struct expression *arg;
834 struct symbol *sym;
835
836 FOR_EACH_PTR(call->args, arg) {
837 if (points_to_user_data(arg))
838 return true;
839 sym = expr_to_sym(arg);
840 if (!sym)
841 continue;
842 if (has_user_data(sym))
843 return true;
844 } END_FOR_EACH_PTR(arg);
845
846 return false;
847 }
848
849 static int db_returned_user_rl(struct expression *call, struct range_list **rl)
850 {
851 struct smatch_state *state;
852 char buf[48];
853
854 if (is_fake_call(call))
855 return 0;
856 snprintf(buf, sizeof(buf), "return %p", call);
857 state = get_state(my_id, buf, NULL);
858 if (!state || !estate_rl(state))
859 return 0;
860 *rl = estate_rl(state);
861 return 1;
862 }
863
864 struct stree *get_user_stree(void)
865 {
866 return get_all_states_stree(my_id);
867 }
868
869 static int user_data_flag;
870 static int no_user_data_flag;
871 struct range_list *var_user_rl(struct expression *expr)
872 {
873 struct smatch_state *state;
874 struct range_list *rl;
875 struct range_list *absolute_rl;
876
877 if (expr->type == EXPR_PREOP && expr->op == '&') {
878 no_user_data_flag = 1;
879 return NULL;
880 }
881
882 if (expr->type == EXPR_BINOP && expr->op == '%') {
883 struct range_list *left, *right;
884
885 if (!get_user_rl(expr->right, &right))
886 return NULL;
887 get_absolute_rl(expr->left, &left);
888 rl = rl_binop(left, '%', right);
889 goto found;
890 }
891
892 if (expr->type == EXPR_BINOP && expr->op == '/') {
893 struct range_list *left = NULL;
894 struct range_list *right = NULL;
895 struct range_list *abs_right;
896
897 /*
898 * The specific bug I'm dealing with is:
899 *
900 * foo = capped_user / unknown;
901 *
902 * Instead of just saying foo is now entirely user_rl we should
903 * probably say instead that it is not at all user data.
904 *
905 */
906
907 get_user_rl(expr->left, &left);
908 get_user_rl(expr->right, &right);
909 get_absolute_rl(expr->right, &abs_right);
910
911 if (left && !right) {
912 rl = rl_binop(left, '/', abs_right);
913 if (sval_cmp(rl_max(left), rl_max(rl)) < 0)
914 no_user_data_flag = 1;
915 }
916
917 return NULL;
918 }
919
920 if (get_rl_from_function(expr, &rl))
921 goto found;
922
923 if (get_user_macro_rl(expr, &rl))
924 goto found;
925
926 if (comes_from_skb_data(expr)) {
927 rl = alloc_whole_rl(get_type(expr));
928 goto found;
929 }
930
931 state = get_state_expr(my_id, expr);
932 if (state && estate_rl(state)) {
933 rl = estate_rl(state);
934 goto found;
935 }
936
937 if (expr->type == EXPR_CALL && db_returned_user_rl(expr, &rl))
938 goto found;
939
940 if (expr->type == EXPR_PREOP && expr->op == '*' &&
941 points_to_user_data(expr->unop)) {
942 rl = var_to_absolute_rl(expr);
943 goto found;
944 }
945
946 if (is_array(expr)) {
947 struct expression *array = get_array_base(expr);
948
949 if (!get_state_expr(my_id, array)) {
950 no_user_data_flag = 1;
951 return NULL;
952 }
953 }
954
955 return NULL;
956 found:
957 user_data_flag = 1;
958 absolute_rl = var_to_absolute_rl(expr);
959 return clone_rl(rl_intersection(rl, absolute_rl));
960 }
961
962 static bool is_ptr_subtract(struct expression *expr)
963 {
964 expr = strip_expr(expr);
965 if (!expr)
966 return false;
967 if (expr->type == EXPR_BINOP && expr->op == '-' &&
968 type_is_ptr(get_type(expr->left))) {
969 return true;
970 }
971 return false;
972 }
973
974 int get_user_rl(struct expression *expr, struct range_list **rl)
975 {
976 if (is_ptr_subtract(expr))
977 return 0;
978
979 user_data_flag = 0;
980 no_user_data_flag = 0;
981 custom_get_absolute_rl(expr, &var_user_rl, rl);
982 if (!user_data_flag || no_user_data_flag)
983 *rl = NULL;
984
985 return !!*rl;
986 }
987
988 int is_user_rl(struct expression *expr)
989 {
990 struct range_list *tmp;
991
992 return get_user_rl(expr, &tmp) && tmp;
993 }
994
995 int get_user_rl_var_sym(const char *name, struct symbol *sym, struct range_list **rl)
996 {
997 struct smatch_state *state;
998
999 state = get_state(my_id, name, sym);
1000 if (state && estate_rl(state)) {
1001 *rl = estate_rl(state);
1002 return 1;
1003 }
1004 return 0;
1005 }
1006
1007 static void return_info_callback(int return_id, char *return_ranges,
1008 struct expression *returned_expr,
1009 int param,
1010 const char *printed_name,
1011 struct sm_state *sm)
1012 {
1013 struct smatch_state *extra;
1014 struct range_list *rl;
1015 char buf[64];
1016
1017 if (param >= 0) {
1018 if (strcmp(printed_name, "$") == 0)
1019 return;
1020 if (!param_was_set_var_sym(sm->name, sm->sym))
1021 return;
1022 }
1023 rl = estate_rl(sm->state);
1024 if (!rl)
1025 return;
1026 extra = get_state(SMATCH_EXTRA, sm->name, sm->sym);
1027 if (estate_rl(extra))
1028 rl = rl_intersection(estate_rl(sm->state), estate_rl(extra));
1029 if (!rl)
1030 return;
1031
1032 snprintf(buf, sizeof(buf), "%s%s%s",
1033 show_rl(rl),
1034 estate_capped(sm->state) ? "[c]" : "",
1035 estate_treat_untagged(sm->state) ? "[u]" : "");
1036 sql_insert_return_states(return_id, return_ranges,
1037 estate_new(sm->state) ? USER_DATA_SET : USER_DATA,
1038 param, printed_name, buf);
1039 }
1040
1041 static void caller_info_callback(struct expression *call, int param, char *printed_name, struct sm_state *sm)
1042 {
1043 struct smatch_state *state;
1044 struct range_list *rl;
1045 struct symbol *type;
1046 char buf[64];
1047
1048 /*
1049 * Smatch uses a hack where if we get an unsigned long we say it's
1050 * both user data and it points to user data. But if we pass it to a
1051 * function which takes an int, then it's just user data. There's not
1052 * enough bytes for it to be a pointer.
1053 *
1054 */
1055 type = get_arg_type(call->fn, param);
1056 if (strcmp(printed_name, "$") != 0 && type && type_bits(type) < type_bits(&ptr_ctype))
1057 return;
1058
1059 if (strcmp(sm->state->name, "") == 0)
1060 return;
1061
1062 state = __get_state(SMATCH_EXTRA, sm->name, sm->sym);
1063 if (!state || !estate_rl(state))
1064 rl = estate_rl(sm->state);
1065 else
1066 rl = rl_intersection(estate_rl(sm->state), estate_rl(state));
1067
1068 if (!rl)
1069 return;
1070
1071 snprintf(buf, sizeof(buf), "%s%s%s", show_rl(rl),
1072 estate_capped(sm->state) ? "[c]" : "",
1073 estate_treat_untagged(sm->state) ? "[u]" : "");
1074 sql_insert_caller_info(call, USER_DATA, param, printed_name, buf);
1075 }
1076
1077 static void db_param_set(struct expression *expr, int param, char *key, char *value)
1078 {
1079 struct expression *arg;
1080 char *name;
1081 struct symbol *sym;
1082 struct smatch_state *state;
1083
1084 while (expr->type == EXPR_ASSIGNMENT)
1085 expr = strip_expr(expr->right);
1086 if (expr->type != EXPR_CALL)
1087 return;
1088
1089 arg = get_argument_from_call_expr(expr->args, param);
1090 if (!arg)
1091 return;
1092 name = get_variable_from_key(arg, key, &sym);
1093 if (!name || !sym)
1094 goto free;
1095
1096 state = get_state(my_id, name, sym);
1097 if (!state)
1098 goto free;
1099
1100 set_state(my_id, name, sym, alloc_estate_empty());
1101 free:
1102 free_string(name);
1103 }
1104
1105 static bool param_data_capped(const char *value)
1106 {
1107 if (strstr(value, ",c") || strstr(value, "[c"))
1108 return true;
1109 return false;
1110 }
1111
1112 static bool param_data_treat_untagged(const char *value)
1113 {
1114 if (strstr(value, ",u") || strstr(value, "[u"))
1115 return true;
1116 return false;
1117 }
1118
1119 static void set_param_user_data(const char *name, struct symbol *sym, char *key, char *value)
1120 {
1121 struct expression *expr;
1122 struct range_list *rl = NULL;
1123 struct smatch_state *state;
1124 struct symbol *type;
1125 char *fullname;
1126
1127 expr = symbol_expression(sym);
1128 fullname = get_variable_from_key(expr, key, NULL);
1129 if (!fullname)
1130 return;
1131
1132 type = get_member_type_from_key(expr, key);
1133 if (type && type->type == SYM_STRUCT)
1134 return;
1135
1136 // FIXME: This is temporary. Just run this on Thursday and then
1137 // let's make it a printf() and then delete it.
1138 if (!type)
1139 return;
1140
1141 str_to_rl(type, value, &rl);
1142 rl = swap_mtag_seed(expr, rl);
1143 state = alloc_estate_rl(rl);
1144 if (param_data_capped(value) || is_capped(expr))
1145 estate_set_capped(state);
1146 if (param_data_treat_untagged(value) || sym->ctype.as == 5)
1147 estate_set_treat_untagged(state);
1148 set_state(my_id, fullname, sym, state);
1149 }
1150
1151 static void set_called(const char *name, struct symbol *sym, char *key, char *value)
1152 {
1153 set_state(my_call_id, "this_function", NULL, &called);
1154 }
1155
1156 static void match_syscall_definition(struct symbol *sym)
1157 {
1158 struct symbol *arg;
1159 char *macro;
1160 char *name;
1161 int is_syscall = 0;
1162
1163 macro = get_macro_name(sym->pos);
1164 if (macro &&
1165 (strncmp("SYSCALL_DEFINE", macro, strlen("SYSCALL_DEFINE")) == 0 ||
1166 strncmp("COMPAT_SYSCALL_DEFINE", macro, strlen("COMPAT_SYSCALL_DEFINE")) == 0))
1167 is_syscall = 1;
1168
1169 name = get_function();
1170 if (!option_no_db && get_state(my_call_id, "this_function", NULL) != &called) {
1171 if (name && strncmp(name, "sys_", 4) == 0)
1172 is_syscall = 1;
1173 }
1174
1175 if (name && strncmp(name, "compat_sys_", 11) == 0)
1176 is_syscall = 1;
1177
1178 if (!is_syscall)
1179 return;
1180
1181 FOR_EACH_PTR(sym->ctype.base_type->arguments, arg) {
1182 set_state(my_id, arg->ident->name, arg, alloc_estate_whole(get_real_base_type(arg)));
1183 } END_FOR_EACH_PTR(arg);
1184 }
1185
1186 #define OLD 0
1187 #define NEW 1
1188
1189 static void store_user_data_return(struct expression *expr, char *key, char *value, bool is_new)
1190 {
1191 struct smatch_state *state;
1192 struct range_list *rl;
1193 struct symbol *type;
1194 char buf[48];
1195
1196 if (key[0] != '$')
1197 return;
1198
1199 type = get_type(expr);
1200 snprintf(buf, sizeof(buf), "return %p%s", expr, key + 1);
1201 call_results_to_rl(expr, type, value, &rl);
1202
1203 state = alloc_estate_rl(rl);
1204 if (is_new)
1205 estate_set_new(state);
1206
1207 set_state(my_id, buf, NULL, state);
1208 }
1209
1210 static void set_to_user_data(struct expression *expr, char *key, char *value, bool is_new)
1211 {
1212 struct smatch_state *state;
1213 char *name;
1214 struct symbol *sym;
1215 struct symbol *type;
1216 struct range_list *rl = NULL;
1217
1218 type = get_member_type_from_key(expr, key);
1219 name = get_variable_from_key(expr, key, &sym);
1220 if (!name || !sym)
1221 goto free;
1222
1223 call_results_to_rl(expr, type, value, &rl);
1224
1225 state = alloc_estate_rl(rl);
1226 if (param_data_capped(value))
1227 estate_set_capped(state);
1228 if (param_data_treat_untagged(value))
1229 estate_set_treat_untagged(state);
1230 if (is_new)
1231 estate_set_new(state);
1232 set_state(my_id, name, sym, state);
1233 free:
1234 free_string(name);
1235 }
1236
1237 static void returns_param_user_data(struct expression *expr, int param, char *key, char *value)
1238 {
1239 struct expression *arg;
1240 struct expression *call;
1241
1242 call = expr;
1243 while (call->type == EXPR_ASSIGNMENT)
1244 call = strip_expr(call->right);
1245 if (call->type != EXPR_CALL)
1246 return;
1247
1248 if (!we_pass_user_data(call))
1249 return;
1250
1251 if (param == -1) {
1252 if (expr->type != EXPR_ASSIGNMENT) {
1253 store_user_data_return(expr, key, value, OLD);
1254 return;
1255 }
1256 set_to_user_data(expr->left, key, value, OLD);
1257 return;
1258 }
1259
1260 arg = get_argument_from_call_expr(call->args, param);
1261 if (!arg)
1262 return;
1263 set_to_user_data(arg, key, value, OLD);
1264 }
1265
1266 static void returns_param_user_data_set(struct expression *expr, int param, char *key, char *value)
1267 {
1268 struct expression *arg;
1269
1270 func_gets_user_data = true;
1271
1272 if (param == -1) {
1273 if (expr->type != EXPR_ASSIGNMENT) {
1274 store_user_data_return(expr, key, value, NEW);
1275 return;
1276 }
1277 set_to_user_data(expr->left, key, value, NEW);
1278 return;
1279 }
1280
1281 while (expr->type == EXPR_ASSIGNMENT)
1282 expr = strip_expr(expr->right);
1283 if (expr->type != EXPR_CALL)
1284 return;
1285
1286 arg = get_argument_from_call_expr(expr->args, param);
1287 if (!arg)
1288 return;
1289 set_to_user_data(arg, key, value, NEW);
1290 }
1291
1292 static void returns_param_capped(struct expression *expr, int param, char *key, char *value)
1293 {
1294 struct smatch_state *state, *new;
1295 struct symbol *sym;
1296 char *name;
1297
1298 name = get_name_sym_from_key(expr, param, key, &sym);
1299 if (!name || !sym)
1300 goto free;
1301
1302 state = get_state(my_id, name, sym);
1303 if (!state || estate_capped(state))
1304 goto free;
1305
1306 new = clone_estate(state);
1307 estate_set_capped(new);
1308
1309 set_state(my_id, name, sym, new);
1310 free:
1311 free_string(name);
1312 }
1313
1314 static void match_function_def(struct symbol *sym)
1315 {
1316 if (is_user_data_fn(sym))
1317 func_gets_user_data = true;
1318 }
1319
1320 void register_kernel_user_data(int id)
1321 {
1322 int i;
1323
1324 my_id = id;
1325
1326 if (option_project != PROJ_KERNEL)
1327 return;
1328
1329 set_dynamic_states(my_id);
1330
1331 add_function_data(&func_gets_user_data);
1332 add_hook(&match_function_def, FUNC_DEF_HOOK);
1333
1334 add_hook(&save_start_states, AFTER_DEF_HOOK);
1335 add_hook(&free_start_states, AFTER_FUNC_HOOK);
1336 add_function_data((unsigned long *)&start_states);
1337
1338 add_unmatched_state_hook(my_id, &empty_state);
1339 add_extra_nomod_hook(&extra_nomod_hook);
1340 add_pre_merge_hook(my_id, &pre_merge_hook);
1341 add_merge_hook(my_id, &merge_estates);
1342
1343 add_function_hook("copy_from_user", &match_user_copy, INT_PTR(0));
1344 add_function_hook("__copy_from_user", &match_user_copy, INT_PTR(0));
1345 add_function_hook("memcpy_fromiovec", &match_user_copy, INT_PTR(0));
1346 for (i = 0; i < ARRAY_SIZE(kstr_funcs); i++)
1347 add_function_hook(kstr_funcs[i], &match_user_copy, INT_PTR(2));
1348 add_function_hook("usb_control_msg", &match_user_copy, INT_PTR(6));
1349
1350 for (i = 0; i < ARRAY_SIZE(returns_user_data); i++)
1351 add_function_hook(returns_user_data[i], &match_returns_user_rl, NULL);
1352
1353 add_function_hook("sscanf", &match_sscanf, NULL);
1354
1355 add_hook(&match_syscall_definition, AFTER_DEF_HOOK);
1356
1357 add_hook(&match_assign, ASSIGNMENT_HOOK);
1358 select_return_states_hook(PARAM_SET, &db_param_set);
1359 add_hook(&match_condition, CONDITION_HOOK);
1360
1361 add_caller_info_callback(my_id, caller_info_callback);
1362 add_return_info_callback(my_id, return_info_callback);
1363 select_caller_info_hook(set_param_user_data, USER_DATA);
1364 select_return_states_hook(USER_DATA, &returns_param_user_data);
1365 select_return_states_hook(USER_DATA_SET, &returns_param_user_data_set);
1366 select_return_states_hook(CAPPED_DATA, &returns_param_capped);
1367 }
1368
1369 void register_kernel_user_data2(int id)
1370 {
1371 my_call_id = id;
1372
1373 if (option_project != PROJ_KERNEL)
1374 return;
1375 select_caller_info_hook(set_called, INTERNAL);
1376 }
1377
Static analysis for C