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",
49 };
50
51 static const char *returns_pointer_to_user_data[] = {
52 "nlmsg_data", "nla_data", "memdup_user", "kmap_atomic", "skb_network_header",
53 };
54
55 static void set_points_to_user_data(struct expression *expr);
56
57 static struct stree *start_states;
58 static struct stree_stack *saved_stack;
59 static void save_start_states(struct statement *stmt)
60 {
61 start_states = clone_stree(__get_cur_stree());
62 }
63
64 static void free_start_states(void)
65 {
66 free_stree(&start_states);
67 }
68
69 static void match_save_states(struct expression *expr)
70 {
71 push_stree(&saved_stack, start_states);
72 start_states = NULL;
73 }
74
75 static void match_restore_states(struct expression *expr)
76 {
77 free_stree(&start_states);
78 start_states = pop_stree(&saved_stack);
79 }
80
81 static struct smatch_state *empty_state(struct sm_state *sm)
82 {
83 return alloc_estate_empty();
84 }
85
86 static void pre_merge_hook(struct sm_state *sm)
87 {
88 struct smatch_state *user;
89 struct smatch_state *extra;
90 struct smatch_state *state;
91 struct range_list *rl;
92 sval_t dummy;
93 sval_t sval_100;
94
95 sval_100.value = 100;
96 sval_100.type = &int_ctype;
97
98 user = __get_state(my_id, sm->name, sm->sym);
99 if (!user || !estate_rl(user))
100 return;
101 extra = __get_state(SMATCH_EXTRA, sm->name, sm->sym);
102 if (!extra)
103 return;
104 rl = rl_intersection(estate_rl(user), estate_rl(extra));
105 if (rl_to_sval(rl, &dummy))
106 rl = NULL;
107 state = alloc_estate_rl(clone_rl(rl));
108 if (estate_capped(user) || is_capped_var_sym(sm->name, sm->sym))
109 estate_set_capped(state);
110 set_state(my_id, sm->name, sm->sym, state);
111 }
112
113 static void extra_nomod_hook(const char *name, struct symbol *sym, struct expression *expr, struct smatch_state *state)
114 {
115 struct smatch_state *user, *new;
116 struct range_list *rl;
117
118 user = __get_state(my_id, name, sym);
119 if (!user)
120 return;
121 rl = rl_intersection(estate_rl(user), estate_rl(state));
122 if (rl_equiv(rl, estate_rl(user)))
123 return;
124 new = alloc_estate_rl(rl);
125 if (estate_capped(user))
126 estate_set_capped(new);
127 set_state(my_id, name, sym, new);
128 }
129
130 static bool binop_capped(struct expression *expr)
131 {
132 struct range_list *left_rl;
133 int comparison;
134
135 if (expr->op == '-' && get_user_rl(expr->left, &left_rl)) {
136 if (user_rl_capped(expr->left))
137 return true;
138 comparison = get_comparison(expr->left, expr->right);
139 if (comparison && show_special(comparison)[0] == '>')
140 return true;
141 return false;
142 }
143
144 if (expr->op == '&' || expr->op == '%') {
145 if (is_capped(expr->left) || is_capped(expr->right))
146 return true;
147 if (user_rl_capped(expr->left) || user_rl_capped(expr->right))
148 return true;
149 return false;
150 }
151
152 if (user_rl_capped(expr->left) &&
153 user_rl_capped(expr->right))
154 return true;
155 return false;
156 }
157
158 bool user_rl_capped(struct expression *expr)
159 {
160 struct smatch_state *state;
161 struct range_list *rl;
162 sval_t sval;
163
164 expr = strip_expr(expr);
165 if (!expr)
166 return false;
167 if (get_value(expr, &sval))
168 return true;
169 if (expr->type == EXPR_BINOP)
170 return binop_capped(expr);
171 if ((expr->type == EXPR_PREOP || expr->type == EXPR_POSTOP) &&
172 (expr->op == SPECIAL_INCREMENT || expr->op == SPECIAL_DECREMENT))
173 return user_rl_capped(expr->unop);
174 state = get_state_expr(my_id, expr);
175 if (state)
176 return estate_capped(state);
177
178 if (get_user_rl(expr, &rl))
179 return false; /* uncapped user data */
180
181 return true; /* not actually user data */
182 }
183
184 static void tag_inner_struct_members(struct expression *expr, struct symbol *member)
185 {
186 struct expression *edge_member;
187 struct symbol *base = get_real_base_type(member);
188 struct symbol *tmp;
189
190 if (member->ident)
191 expr = member_expression(expr, '.', member->ident);
192
193 FOR_EACH_PTR(base->symbol_list, tmp) {
194 struct symbol *type;
195
196 type = get_real_base_type(tmp);
197 if (!type)
198 continue;
199
200 if (type->type == SYM_UNION || type->type == SYM_STRUCT) {
201 tag_inner_struct_members(expr, tmp);
202 continue;
203 }
204
205 if (!tmp->ident)
206 continue;
207
208 edge_member = member_expression(expr, '.', tmp->ident);
209 set_state_expr(my_id, edge_member, alloc_estate_whole(type));
210 } END_FOR_EACH_PTR(tmp);
211 }
212
213 static void tag_struct_members(struct symbol *type, struct expression *expr)
214 {
215 struct symbol *tmp;
216 struct expression *member;
217 int op = '*';
218
219 if (expr->type == EXPR_PREOP && expr->op == '&') {
220 expr = strip_expr(expr->unop);
221 op = '.';
222 }
223
224 FOR_EACH_PTR(type->symbol_list, tmp) {
225 type = get_real_base_type(tmp);
226 if (!type)
227 continue;
228
229 if (type->type == SYM_UNION || type->type == SYM_STRUCT) {
230 tag_inner_struct_members(expr, tmp);
231 continue;
232 }
233
234 if (!tmp->ident)
235 continue;
236
237 member = member_expression(expr, op, tmp->ident);
238 set_state_expr(my_id, member, alloc_estate_whole(get_type(member)));
239
240 if (type->type == SYM_ARRAY)
241 set_points_to_user_data(member);
242 } END_FOR_EACH_PTR(tmp);
243 }
244
245 static void tag_base_type(struct expression *expr)
246 {
247 if (expr->type == EXPR_PREOP && expr->op == '&')
248 expr = strip_expr(expr->unop);
249 else
250 expr = deref_expression(expr);
251 set_state_expr(my_id, expr, alloc_estate_whole(get_type(expr)));
252 }
253
254 static void tag_as_user_data(struct expression *expr)
255 {
256 struct symbol *type;
257
258 expr = strip_expr(expr);
259
260 type = get_type(expr);
261 if (!type || type->type != SYM_PTR)
262 return;
263 type = get_real_base_type(type);
264 if (!type)
265 return;
266 if (type == &void_ctype) {
267 set_state_expr(my_id, deref_expression(expr), alloc_estate_whole(&ulong_ctype));
268 return;
269 }
270 if (type->type == SYM_BASETYPE)
271 tag_base_type(expr);
272 if (type->type == SYM_STRUCT || type->type == SYM_UNION) {
273 if (expr->type != EXPR_PREOP || expr->op != '&')
274 expr = deref_expression(expr);
275 else
276 set_state_expr(my_id, deref_expression(expr), alloc_estate_whole(&ulong_ctype));
277 tag_struct_members(type, expr);
278 }
279 }
280
281 static void match_user_copy(const char *fn, struct expression *expr, void *_param)
282 {
283 int param = PTR_INT(_param);
284 struct expression *dest;
285
286 func_gets_user_data = true;
287
288 dest = get_argument_from_call_expr(expr->args, param);
289 dest = strip_expr(dest);
290 if (!dest)
291 return;
292 tag_as_user_data(dest);
293 }
294
295 static int is_dev_attr_name(struct expression *expr)
296 {
297 char *name;
298 int ret = 0;
299
300 name = expr_to_str(expr);
301 if (!name)
302 return 0;
303 if (strstr(name, "->attr.name"))
304 ret = 1;
305 free_string(name);
306 return ret;
307 }
308
309 static int ends_in_n(struct expression *expr)
310 {
311 struct string *str;
312
313 if (!expr)
314 return 0;
315 if (expr->type != EXPR_STRING || !expr->string)
316 return 0;
317
318 str = expr->string;
319 if (str->length < 3)
320 return 0;
321
322 if (str->data[str->length - 3] == '%' &&
323 str->data[str->length - 2] == 'n')
324 return 1;
325 return 0;
326 }
327
328 static void match_sscanf(const char *fn, struct expression *expr, void *unused)
329 {
330 struct expression *str, *format, *arg;
331 int i, last;
332
333 func_gets_user_data = true;
334
335 str = get_argument_from_call_expr(expr->args, 0);
336 if (is_dev_attr_name(str))
337 return;
338
339 format = get_argument_from_call_expr(expr->args, 1);
340 if (is_dev_attr_name(format))
341 return;
342
343 last = ptr_list_size((struct ptr_list *)expr->args) - 1;
344
345 i = -1;
346 FOR_EACH_PTR(expr->args, arg) {
347 i++;
348 if (i < 2)
349 continue;
350 if (i == last && ends_in_n(format))
351 continue;
352 tag_as_user_data(arg);
353 } END_FOR_EACH_PTR(arg);
354 }
355
356 static int is_skb_data(struct expression *expr)
357 {
358 struct symbol *sym;
359
360 if (!expr)
361 return 0;
362
363 if (expr->type == EXPR_BINOP && expr->op == '+')
364 return is_skb_data(expr->left);
365
366 expr = strip_expr(expr);
367 if (!expr)
368 return 0;
369 if (expr->type != EXPR_DEREF || expr->op != '.')
370 return 0;
371
372 if (!expr->member)
373 return 0;
374 if (strcmp(expr->member->name, "data") != 0)
375 return 0;
376
377 sym = expr_to_sym(expr->deref);
378 if (!sym)
379 return 0;
380 sym = get_real_base_type(sym);
381 if (!sym || sym->type != SYM_PTR)
382 return 0;
383 sym = get_real_base_type(sym);
384 if (!sym || sym->type != SYM_STRUCT || !sym->ident)
385 return 0;
386 if (strcmp(sym->ident->name, "sk_buff") != 0)
387 return 0;
388
389 return 1;
390 }
391
392 static bool is_points_to_user_data_fn(struct expression *expr)
393 {
394 int i;
395
396 expr = strip_expr(expr);
397 if (expr->type != EXPR_CALL || expr->fn->type != EXPR_SYMBOL ||
398 !expr->fn->symbol)
399 return false;
400 expr = expr->fn;
401 for (i = 0; i < ARRAY_SIZE(returns_pointer_to_user_data); i++) {
402 if (sym_name_is(returns_pointer_to_user_data[i], expr))
403 return true;
404 }
405 return false;
406 }
407
408 static int get_rl_from_function(struct expression *expr, struct range_list **rl)
409 {
410 int i;
411
412 if (expr->type != EXPR_CALL || expr->fn->type != EXPR_SYMBOL ||
413 !expr->fn->symbol_name || !expr->fn->symbol_name->name)
414 return 0;
415
416 for (i = 0; i < ARRAY_SIZE(returns_user_data); i++) {
417 if (strcmp(expr->fn->symbol_name->name, returns_user_data[i]) == 0) {
418 *rl = alloc_whole_rl(get_type(expr));
419 return 1;
420 }
421 }
422 return 0;
423 }
424
425 int points_to_user_data(struct expression *expr)
426 {
427 struct smatch_state *state;
428 struct range_list *rl;
429 char buf[256];
430 struct symbol *sym;
431 char *name;
432 int ret = 0;
433
434 expr = strip_expr(expr);
435 if (!expr)
436 return 0;
437 if (is_skb_data(expr))
438 return 1;
439 if (is_points_to_user_data_fn(expr))
440 return 1;
441 if (get_rl_from_function(expr, &rl))
442 return 1;
443
444 if (expr->type == EXPR_BINOP && expr->op == '+') {
445 if (points_to_user_data(expr->left))
446 return 1;
447 if (points_to_user_data(expr->right))
448 return 1;
449 return 0;
450 }
451
452 name = expr_to_var_sym(expr, &sym);
453 if (!name || !sym)
454 goto free;
455 snprintf(buf, sizeof(buf), "*%s", name);
456 state = __get_state(my_id, buf, sym);
457 if (state && estate_rl(state))
458 ret = 1;
459 free:
460 free_string(name);
461 return ret;
462 }
463
464 static void set_points_to_user_data(struct expression *expr)
465 {
466 char *name;
467 struct symbol *sym;
468 char buf[256];
469 struct symbol *type;
470
471 name = expr_to_var_sym(expr, &sym);
472 if (!name || !sym)
473 goto free;
474 snprintf(buf, sizeof(buf), "*%s", name);
475 type = get_type(expr);
476 if (type && type->type == SYM_PTR)
477 type = get_real_base_type(type);
478 if (!type || type->type != SYM_BASETYPE)
479 type = &llong_ctype;
480 set_state(my_id, buf, sym, alloc_estate_whole(type));
481 free:
482 free_string(name);
483 }
484
485 static int comes_from_skb_data(struct expression *expr)
486 {
487 expr = strip_expr(expr);
488 if (!expr || expr->type != EXPR_PREOP || expr->op != '*')
489 return 0;
490
491 expr = strip_expr(expr->unop);
492 if (!expr)
493 return 0;
494 if (expr->type == EXPR_BINOP && expr->op == '+')
495 expr = strip_expr(expr->left);
496
497 return is_skb_data(expr);
498 }
499
500 static int handle_struct_assignment(struct expression *expr)
501 {
502 struct expression *right;
503 struct symbol *left_type, *right_type;
504
505 left_type = get_type(expr->left);
506 if (!left_type || left_type->type != SYM_PTR)
507 return 0;
508 left_type = get_real_base_type(left_type);
509 if (!left_type)
510 return 0;
511 if (left_type->type != SYM_STRUCT &&
512 left_type->type != SYM_UNION)
513 return 0;
514
515 /*
516 * Ignore struct to struct assignments because for those we look at the
517 * individual members.
518 */
519 right = strip_expr(expr->right);
520 right_type = get_type(right);
521 if (!right_type || right_type->type != SYM_PTR)
522 return 0;
523
524 /* If we are assigning struct members then normally that is handled
525 * by fake assignments, however if we cast one struct to a different
526 * of struct then we handle that here.
527 */
528 right_type = get_real_base_type(right_type);
529 if (right_type == left_type)
530 return 0;
531
532 if (!points_to_user_data(right))
533 return 0;
534
535 tag_as_user_data(expr->left);
536 return 1;
537 }
538
539 static int handle_get_user(struct expression *expr)
540 {
541 char *name;
542 int ret = 0;
543
544 name = get_macro_name(expr->pos);
545 if (!name || strcmp(name, "get_user") != 0)
546 return 0;
547
548 name = expr_to_var(expr->right);
549 if (!name || strcmp(name, "__val_gu") != 0)
550 goto free;
551 set_state_expr(my_id, expr->left, alloc_estate_whole(get_type(expr->left)));
552 ret = 1;
553 free:
554 free_string(name);
555 return ret;
556 }
557
558 static bool handle_op_assign(struct expression *expr)
559 {
560 struct expression *binop_expr;
561 struct smatch_state *state;
562 struct range_list *rl;
563
564 switch (expr->op) {
565 case SPECIAL_ADD_ASSIGN:
566 case SPECIAL_SUB_ASSIGN:
567 case SPECIAL_AND_ASSIGN:
568 case SPECIAL_MOD_ASSIGN:
569 case SPECIAL_SHL_ASSIGN:
570 case SPECIAL_SHR_ASSIGN:
571 case SPECIAL_OR_ASSIGN:
572 case SPECIAL_XOR_ASSIGN:
573 case SPECIAL_MUL_ASSIGN:
574 case SPECIAL_DIV_ASSIGN:
575 binop_expr = binop_expression(expr->left,
576 op_remove_assign(expr->op),
577 expr->right);
578 if (!get_user_rl(binop_expr, &rl))
579 return true;
580
581 rl = cast_rl(get_type(expr->left), rl);
582 state = alloc_estate_rl(rl);
583 if (user_rl_capped(binop_expr))
584 estate_set_capped(state);
585 set_state_expr(my_id, expr->left, state);
586 return true;
587 }
588 return false;
589 }
590
591 static void match_assign(struct expression *expr)
592 {
593 struct range_list *rl;
594 static struct expression *handled;
595 struct smatch_state *state;
596 struct expression *faked;
597
598 faked = get_faked_expression();
599 if (faked && faked == handled)
600 return;
601 if (is_fake_call(expr->right))
602 goto clear_old_state;
603 if (handle_get_user(expr))
604 return;
605 if (points_to_user_data(expr->right)) {
606 handled = expr;
607 set_points_to_user_data(expr->left);
608 }
609 if (handle_struct_assignment(expr))
610 return;
611
612 if (handle_op_assign(expr))
613 return;
614 if (expr->op != '=')
615 goto clear_old_state;
616
617 /* Handled by DB code */
618 if (expr->right->type == EXPR_CALL || __in_fake_parameter_assign)
619 return;
620
621 if (!get_user_rl(expr->right, &rl))
622 goto clear_old_state;
623
624 rl = cast_rl(get_type(expr->left), rl);
625 state = alloc_estate_rl(rl);
626 if (user_rl_capped(expr->right))
627 estate_set_capped(state);
628 set_state_expr(my_id, expr->left, state);
629
630 return;
631
632 clear_old_state:
633 if (get_state_expr(my_id, expr->left))
634 set_state_expr(my_id, expr->left, alloc_estate_empty());
635 }
636
637 static void handle_eq_noteq(struct expression *expr)
638 {
639 struct smatch_state *left_orig, *right_orig;
640
641 left_orig = get_state_expr(my_id, expr->left);
642 right_orig = get_state_expr(my_id, expr->right);
643
644 if (!left_orig && !right_orig)
645 return;
646 if (left_orig && right_orig)
647 return;
648
649 if (left_orig) {
650 set_true_false_states_expr(my_id, expr->left,
651 expr->op == SPECIAL_EQUAL ? alloc_estate_empty() : NULL,
652 expr->op == SPECIAL_EQUAL ? NULL : alloc_estate_empty());
653 } else {
654 set_true_false_states_expr(my_id, expr->right,
655 expr->op == SPECIAL_EQUAL ? alloc_estate_empty() : NULL,
656 expr->op == SPECIAL_EQUAL ? NULL : alloc_estate_empty());
657 }
658 }
659
660 static struct range_list *strip_negatives(struct range_list *rl)
661 {
662 sval_t min = rl_min(rl);
663 sval_t minus_one;
664 sval_t over;
665 sval_t max = sval_type_max(rl_type(rl));
666
667 minus_one.type = rl_type(rl);
668 minus_one.value = INT_MAX + 1ULL;
669 over.type = rl_type(rl);
670 over.value = -1;
671
672 if (!rl)
673 return NULL;
674
675 if (type_unsigned(rl_type(rl)) && type_bits(rl_type(rl)) > 31)
676 return remove_range(rl, over, max);
677
678 return remove_range(rl, min, minus_one);
679 }
680
681 static void handle_compare(struct expression *expr)
682 {
683 struct expression *left, *right;
684 struct range_list *left_rl = NULL;
685 struct range_list *right_rl = NULL;
686 struct range_list *user_rl;
687 struct smatch_state *capped_state;
688 struct smatch_state *left_true = NULL;
689 struct smatch_state *left_false = NULL;
690 struct smatch_state *right_true = NULL;
691 struct smatch_state *right_false = NULL;
692 struct symbol *type;
693 sval_t sval;
694
695 left = strip_expr(expr->left);
696 right = strip_expr(expr->right);
697
698 while (left->type == EXPR_ASSIGNMENT)
699 left = strip_expr(left->left);
700
701 /*
702 * Conditions are mostly handled by smatch_extra.c, but there are some
703 * times where the exact values are not known so we can't do that.
704 *
705 * Normally, we might consider using smatch_capped.c to supliment smatch
706 * extra but that doesn't work when we merge unknown uncapped kernel
707 * data with unknown capped user data. The result is uncapped user
708 * data. We need to keep it separate and say that the user data is
709 * capped. In the past, I would have marked this as just regular
710 * kernel data (not user data) but we can't do that these days because
711 * we need to track user data for Spectre.
712 *
713 * The other situation which we have to handle is when we do have an
714 * int and we compare against an unknown unsigned kernel variable. In
715 * that situation we assume that the kernel data is less than INT_MAX.
716 * Otherwise then we get all sorts of array underflow false positives.
717 *
718 */
719
720 /* Handled in smatch_extra.c */
721 if (get_implied_value(left, &sval) ||
722 get_implied_value(right, &sval))
723 return;
724
725 get_user_rl(left, &left_rl);
726 get_user_rl(right, &right_rl);
727
728 /* nothing to do */
729 if (!left_rl && !right_rl)
730 return;
731 /* if both sides are user data that's not a good limit */
732 if (left_rl && right_rl)
733 return;
734
735 if (left_rl)
736 user_rl = left_rl;
737 else
738 user_rl = right_rl;
739
740 type = get_type(expr);
741 if (type_unsigned(type))
742 user_rl = strip_negatives(user_rl);
743 capped_state = alloc_estate_rl(user_rl);
744 estate_set_capped(capped_state);
745
746 switch (expr->op) {
747 case '<':
748 case SPECIAL_UNSIGNED_LT:
749 case SPECIAL_LTE:
750 case SPECIAL_UNSIGNED_LTE:
751 if (left_rl)
752 left_true = capped_state;
753 else
754 right_false = capped_state;
755 break;
756 case '>':
757 case SPECIAL_UNSIGNED_GT:
758 case SPECIAL_GTE:
759 case SPECIAL_UNSIGNED_GTE:
760 if (left_rl)
761 left_false = capped_state;
762 else
763 right_true = capped_state;
764 break;
765 }
766
767 set_true_false_states_expr(my_id, left, left_true, left_false);
768 set_true_false_states_expr(my_id, right, right_true, right_false);
769 }
770
771 static void match_condition(struct expression *expr)
772 {
773 if (expr->type != EXPR_COMPARE)
774 return;
775
776 if (expr->op == SPECIAL_EQUAL ||
777 expr->op == SPECIAL_NOTEQUAL) {
778 handle_eq_noteq(expr);
779 return;
780 }
781
782 handle_compare(expr);
783 }
784
785 static void match_user_assign_function(const char *fn, struct expression *expr, void *unused)
786 {
787 tag_as_user_data(expr->left);
788 set_points_to_user_data(expr->left);
789 }
790
791 static void match_returns_user_rl(const char *fn, struct expression *expr, void *unused)
792 {
793 func_gets_user_data = true;
794 }
795
796 static int get_user_macro_rl(struct expression *expr, struct range_list **rl)
797 {
798 struct expression *parent;
799 char *macro;
800
801 if (!expr)
802 return 0;
803
804 macro = get_macro_name(expr->pos);
805 if (!macro)
806 return 0;
807
808 /* handle ntohl(foo[i]) where "i" is trusted */
809 parent = expr_get_parent_expr(expr);
810 while (parent && parent->type != EXPR_BINOP)
811 parent = expr_get_parent_expr(parent);
812 if (parent && parent->type == EXPR_BINOP) {
813 char *parent_macro = get_macro_name(parent->pos);
814
815 if (parent_macro && strcmp(macro, parent_macro) == 0)
816 return 0;
817 }
818
819 if (strcmp(macro, "ntohl") == 0) {
820 *rl = alloc_whole_rl(&uint_ctype);
821 return 1;
822 }
823 if (strcmp(macro, "ntohs") == 0) {
824 *rl = alloc_whole_rl(&ushort_ctype);
825 return 1;
826 }
827 return 0;
828 }
829
830 static int has_user_data(struct symbol *sym)
831 {
832 struct sm_state *tmp;
833
834 FOR_EACH_MY_SM(my_id, __get_cur_stree(), tmp) {
835 if (tmp->sym == sym)
836 return 1;
837 } END_FOR_EACH_SM(tmp);
838 return 0;
839 }
840
841 static int we_pass_user_data(struct expression *call)
842 {
843 struct expression *arg;
844 struct symbol *sym;
845
846 FOR_EACH_PTR(call->args, arg) {
847 sym = expr_to_sym(arg);
848 if (!sym)
849 continue;
850 if (has_user_data(sym))
851 return 1;
852 } END_FOR_EACH_PTR(arg);
853
854 return 0;
855 }
856
857 static int db_returned_user_rl(struct expression *call, struct range_list **rl)
858 {
859 struct smatch_state *state;
860 char buf[48];
861
862 if (is_fake_call(call))
863 return 0;
864 snprintf(buf, sizeof(buf), "return %p", call);
865 state = get_state(my_id, buf, NULL);
866 if (!state || !estate_rl(state))
867 return 0;
868 *rl = estate_rl(state);
869 return 1;
870 }
871
872 struct stree *get_user_stree(void)
873 {
874 return get_all_states_stree(my_id);
875 }
876
877 static int user_data_flag;
878 static int no_user_data_flag;
879 struct range_list *var_user_rl(struct expression *expr)
880 {
881 struct smatch_state *state;
882 struct range_list *rl;
883 struct range_list *absolute_rl;
884
885 if (expr->type == EXPR_PREOP && expr->op == '&') {
886 no_user_data_flag = 1;
887 return NULL;
888 }
889
890 if (expr->type == EXPR_BINOP && expr->op == '%') {
891 struct range_list *left, *right;
892
893 if (!get_user_rl(expr->right, &right))
894 return NULL;
895 get_absolute_rl(expr->left, &left);
896 rl = rl_binop(left, '%', right);
897 goto found;
898 }
899
900 if (expr->type == EXPR_BINOP && expr->op == '/') {
901 struct range_list *left = NULL;
902 struct range_list *right = NULL;
903 struct range_list *abs_right;
904
905 /*
906 * The specific bug I'm dealing with is:
907 *
908 * foo = capped_user / unknown;
909 *
910 * Instead of just saying foo is now entirely user_rl we should
911 * probably say instead that it is not at all user data.
912 *
913 */
914
915 get_user_rl(expr->left, &left);
916 get_user_rl(expr->right, &right);
917 get_absolute_rl(expr->right, &abs_right);
918
919 if (left && !right) {
920 rl = rl_binop(left, '/', abs_right);
921 if (sval_cmp(rl_max(left), rl_max(rl)) < 0)
922 no_user_data_flag = 1;
923 }
924
925 return NULL;
926 }
927
928 if (get_rl_from_function(expr, &rl))
929 goto found;
930
931 if (get_user_macro_rl(expr, &rl))
932 goto found;
933
934 if (comes_from_skb_data(expr)) {
935 rl = alloc_whole_rl(get_type(expr));
936 goto found;
937 }
938
939 state = get_state_expr(my_id, expr);
940 if (state && estate_rl(state)) {
941 rl = estate_rl(state);
942 goto found;
943 }
944
945 if (expr->type == EXPR_CALL && db_returned_user_rl(expr, &rl))
946 goto found;
947
948 if (is_array(expr)) {
949 struct expression *array = get_array_base(expr);
950
951 if (!get_state_expr(my_id, array)) {
952 no_user_data_flag = 1;
953 return NULL;
954 }
955 }
956
957 if (expr->type == EXPR_PREOP && expr->op == '*' &&
958 is_user_rl(expr->unop)) {
959 rl = var_to_absolute_rl(expr);
960 goto found;
961 }
962
963 return NULL;
964 found:
965 user_data_flag = 1;
966 absolute_rl = var_to_absolute_rl(expr);
967 return clone_rl(rl_intersection(rl, absolute_rl));
968 }
969
970 static bool is_ptr_subtract(struct expression *expr)
971 {
972 expr = strip_expr(expr);
973 if (!expr)
974 return false;
975 if (expr->type == EXPR_BINOP && expr->op == '-' &&
976 type_is_ptr(get_type(expr->left))) {
977 return true;
978 }
979 return false;
980 }
981
982 int get_user_rl(struct expression *expr, struct range_list **rl)
983 {
984 if (is_ptr_subtract(expr))
985 return 0;
986
987 user_data_flag = 0;
988 no_user_data_flag = 0;
989 custom_get_absolute_rl(expr, &var_user_rl, rl);
990 if (!user_data_flag || no_user_data_flag)
991 *rl = NULL;
992
993 return !!*rl;
994 }
995
996 int is_user_rl(struct expression *expr)
997 {
998 struct range_list *tmp;
999
1000 return !!get_user_rl(expr, &tmp);
1001 }
1002
1003 int get_user_rl_var_sym(const char *name, struct symbol *sym, struct range_list **rl)
1004 {
1005 struct smatch_state *state;
1006
1007 state = get_state(my_id, name, sym);
1008 if (state && estate_rl(state)) {
1009 *rl = estate_rl(state);
1010 return 1;
1011 }
1012 return 0;
1013 }
1014
1015 static char *get_user_rl_str(struct expression *expr, struct symbol *type)
1016 {
1017 struct range_list *rl;
1018 static char buf[64];
1019
1020 if (!get_user_rl(expr, &rl))
1021 return NULL;
1022 rl = cast_rl(type, rl);
1023 snprintf(buf, sizeof(buf), "%s%s",
1024 show_rl(rl), user_rl_capped(expr) ? "[c]" : "");
1025 return buf;
1026 }
1027
1028 static void match_call_info(struct expression *expr)
1029 {
1030 struct expression *arg;
1031 struct symbol *type;
1032 char *str;
1033 int i;
1034
1035 i = -1;
1036 FOR_EACH_PTR(expr->args, arg) {
1037 i++;
1038 type = get_arg_type(expr->fn, i);
1039 str = get_user_rl_str(arg, type);
1040 if (!str)
1041 continue;
1042
1043 sql_insert_caller_info(expr, USER_DATA, i, "$", str);
1044 } END_FOR_EACH_PTR(arg);
1045 }
1046
1047 static int is_struct_ptr(struct symbol *sym)
1048 {
1049 struct symbol *type;
1050
1051 if (!sym)
1052 return 0;
1053 type = get_real_base_type(sym);
1054 if (!type || type->type != SYM_PTR)
1055 return 0;
1056 type = get_real_base_type(type);
1057 if (!type || type->type != SYM_STRUCT)
1058 return 0;
1059 return 1;
1060 }
1061
1062 static void struct_member_callback(struct expression *call, int param, char *printed_name, struct sm_state *sm)
1063 {
1064 struct smatch_state *state;
1065 struct range_list *rl;
1066 struct symbol *type;
1067 char buf[64];
1068
1069 /*
1070 * Smatch uses a hack where if we get an unsigned long we say it's
1071 * both user data and it points to user data. But if we pass it to a
1072 * function which takes an int, then it's just user data. There's not
1073 * enough bytes for it to be a pointer.
1074 *
1075 */
1076 type = get_arg_type(call->fn, param);
1077 if (type && type_bits(type) < type_bits(&ptr_ctype))
1078 return;
1079
1080 if (strcmp(sm->state->name, "") == 0)
1081 return;
1082
1083 if (strcmp(printed_name, "*$") == 0 &&
1084 is_struct_ptr(sm->sym))
1085 return;
1086
1087 state = __get_state(SMATCH_EXTRA, sm->name, sm->sym);
1088 if (!state || !estate_rl(state))
1089 rl = estate_rl(sm->state);
1090 else
1091 rl = rl_intersection(estate_rl(sm->state), estate_rl(state));
1092
1093 if (!rl)
1094 return;
1095
1096 snprintf(buf, sizeof(buf), "%s%s", show_rl(rl),
1097 estate_capped(sm->state) ? "[c]" : "");
1098 sql_insert_caller_info(call, USER_DATA, param, printed_name, buf);
1099 }
1100
1101 static void db_param_set(struct expression *expr, int param, char *key, char *value)
1102 {
1103 struct expression *arg;
1104 char *name;
1105 struct symbol *sym;
1106 struct smatch_state *state;
1107
1108 while (expr->type == EXPR_ASSIGNMENT)
1109 expr = strip_expr(expr->right);
1110 if (expr->type != EXPR_CALL)
1111 return;
1112
1113 arg = get_argument_from_call_expr(expr->args, param);
1114 if (!arg)
1115 return;
1116 name = get_variable_from_key(arg, key, &sym);
1117 if (!name || !sym)
1118 goto free;
1119
1120 state = get_state(my_id, name, sym);
1121 if (!state)
1122 goto free;
1123
1124 set_state(my_id, name, sym, alloc_estate_empty());
1125 free:
1126 free_string(name);
1127 }
1128
1129 static bool param_data_capped(const char *value)
1130 {
1131 if (strstr(value, ",c") || strstr(value, "[c"))
1132 return true;
1133 return false;
1134 }
1135
1136 static void set_param_user_data(const char *name, struct symbol *sym, char *key, char *value)
1137 {
1138 struct range_list *rl = NULL;
1139 struct smatch_state *state;
1140 struct expression *expr;
1141 struct symbol *type;
1142 char fullname[256];
1143 char *key_orig = key;
1144 bool add_star = false;
1145
1146 if (strcmp(key, "**$") == 0) {
1147 snprintf(fullname, sizeof(fullname), "**%s", name);
1148 } else {
1149 if (key[0] == '*') {
1150 add_star = true;
1151 key++;
1152 }
1153
1154 snprintf(fullname, 256, "%s%s%s", add_star ? "*" : "", name, key + 1);
1155 }
1156
1157 expr = symbol_expression(sym);
1158 type = get_member_type_from_key(expr, key_orig);
1159
1160 /*
1161 * Say this function takes a struct ponter but the caller passes
1162 * this_function(skb->data). We have two options, we could pass *$
1163 * as user data or we could pass foo->bar, foo->baz as user data.
1164 * The second option is easier to implement so we do that.
1165 *
1166 */
1167 if (strcmp(key_orig, "*$") == 0) {
1168 struct symbol *tmp = type;
1169
1170 while (tmp && tmp->type == SYM_PTR)
1171 tmp = get_real_base_type(tmp);
1172
1173 if (tmp && (tmp->type == SYM_STRUCT || tmp->type == SYM_UNION)) {
1174 tag_as_user_data(symbol_expression(sym));
1175 return;
1176 }
1177 }
1178
1179 str_to_rl(type, value, &rl);
1180 state = alloc_estate_rl(rl);
1181 if (param_data_capped(value) || is_capped(expr))
1182 estate_set_capped(state);
1183 set_state(my_id, fullname, sym, state);
1184 }
1185
1186 static void set_called(const char *name, struct symbol *sym, char *key, char *value)
1187 {
1188 set_state(my_call_id, "this_function", NULL, &called);
1189 }
1190
1191 static void match_syscall_definition(struct symbol *sym)
1192 {
1193 struct symbol *arg;
1194 char *macro;
1195 char *name;
1196 int is_syscall = 0;
1197
1198 macro = get_macro_name(sym->pos);
1199 if (macro &&
1200 (strncmp("SYSCALL_DEFINE", macro, strlen("SYSCALL_DEFINE")) == 0 ||
1201 strncmp("COMPAT_SYSCALL_DEFINE", macro, strlen("COMPAT_SYSCALL_DEFINE")) == 0))
1202 is_syscall = 1;
1203
1204 name = get_function();
1205 if (!option_no_db && get_state(my_call_id, "this_function", NULL) != &called) {
1206 if (name && strncmp(name, "sys_", 4) == 0)
1207 is_syscall = 1;
1208 }
1209
1210 if (name && strncmp(name, "compat_sys_", 11) == 0)
1211 is_syscall = 1;
1212
1213 if (!is_syscall)
1214 return;
1215
1216 FOR_EACH_PTR(sym->ctype.base_type->arguments, arg) {
1217 set_state(my_id, arg->ident->name, arg, alloc_estate_whole(get_real_base_type(arg)));
1218 } END_FOR_EACH_PTR(arg);
1219 }
1220
1221 static void store_user_data_return(struct expression *expr, char *key, char *value)
1222 {
1223 struct range_list *rl;
1224 struct symbol *type;
1225 char buf[48];
1226
1227 if (strcmp(key, "$") != 0)
1228 return;
1229
1230 type = get_type(expr);
1231 snprintf(buf, sizeof(buf), "return %p", expr);
1232 call_results_to_rl(expr, type, value, &rl);
1233
1234 set_state(my_id, buf, NULL, alloc_estate_rl(rl));
1235 }
1236
1237 static void set_to_user_data(struct expression *expr, char *key, char *value)
1238 {
1239 struct smatch_state *state;
1240 char *name;
1241 struct symbol *sym;
1242 struct symbol *type;
1243 struct range_list *rl = NULL;
1244
1245 type = get_member_type_from_key(expr, key);
1246 name = get_variable_from_key(expr, key, &sym);
1247 if (!name || !sym)
1248 goto free;
1249
1250 call_results_to_rl(expr, type, value, &rl);
1251
1252 state = alloc_estate_rl(rl);
1253 if (param_data_capped(value))
1254 estate_set_capped(state);
1255 set_state(my_id, name, sym, state);
1256 free:
1257 free_string(name);
1258 }
1259
1260 static void returns_param_user_data(struct expression *expr, int param, char *key, char *value)
1261 {
1262 struct expression *arg;
1263 struct expression *call;
1264
1265 call = expr;
1266 while (call->type == EXPR_ASSIGNMENT)
1267 call = strip_expr(call->right);
1268 if (call->type != EXPR_CALL)
1269 return;
1270
1271 if (!we_pass_user_data(call))
1272 return;
1273
1274 if (param == -1) {
1275 if (expr->type != EXPR_ASSIGNMENT) {
1276 store_user_data_return(expr, key, value);
1277 return;
1278 }
1279 set_to_user_data(expr->left, key, value);
1280 return;
1281 }
1282
1283 arg = get_argument_from_call_expr(call->args, param);
1284 if (!arg)
1285 return;
1286 set_to_user_data(arg, key, value);
1287 }
1288
1289 static void returns_param_user_data_set(struct expression *expr, int param, char *key, char *value)
1290 {
1291 struct expression *arg;
1292
1293 func_gets_user_data = true;
1294
1295 if (param == -1) {
1296 if (expr->type != EXPR_ASSIGNMENT) {
1297 store_user_data_return(expr, key, value);
1298 return;
1299 }
1300 if (strcmp(key, "*$") == 0) {
1301 set_points_to_user_data(expr->left);
1302 tag_as_user_data(expr->left);
1303 } else {
1304 set_to_user_data(expr->left, key, value);
1305 }
1306 return;
1307 }
1308
1309 while (expr->type == EXPR_ASSIGNMENT)
1310 expr = strip_expr(expr->right);
1311 if (expr->type != EXPR_CALL)
1312 return;
1313
1314 arg = get_argument_from_call_expr(expr->args, param);
1315 if (!arg)
1316 return;
1317 set_to_user_data(arg, key, value);
1318 }
1319
1320 static void param_set_to_user_data(int return_id, char *return_ranges, struct expression *expr)
1321 {
1322 struct sm_state *sm;
1323 struct smatch_state *start_state;
1324 struct range_list *rl;
1325 int param;
1326 char *return_str;
1327 const char *param_name;
1328 struct symbol *ret_sym;
1329 bool return_found = false;
1330 bool pointed_at_found = false;
1331 char buf[64];
1332
1333 expr = strip_expr(expr);
1334 return_str = expr_to_str(expr);
1335 ret_sym = expr_to_sym(expr);
1336
1337 FOR_EACH_MY_SM(my_id, __get_cur_stree(), sm) {
1338 param = get_param_num_from_sym(sm->sym);
1339 if (param < 0)
1340 continue;
1341
1342 if (!param_was_set_var_sym(sm->name, sm->sym))
1343 continue;
1344
1345 /* The logic here was that if we were passed in a user data then
1346 * we don't record that. It's like the difference between
1347 * param_filter and param_set. When I think about it, I'm not
1348 * sure it actually works. It's probably harmless because we
1349 * checked earlier that we're not returning a parameter...
1350 * Let's mark this as a TODO.
1351 */
1352 start_state = get_state_stree(start_states, my_id, sm->name, sm->sym);
1353 if (start_state && rl_equiv(estate_rl(sm->state), estate_rl(start_state)))
1354 continue;
1355
1356 param_name = get_param_name(sm);
1357 if (!param_name)
1358 continue;
1359 if (strcmp(param_name, "$") == 0) /* The -1 param is handled after the loop */
1360 continue;
1361
1362 snprintf(buf, sizeof(buf), "%s%s",
1363 show_rl(estate_rl(sm->state)),
1364 estate_capped(sm->state) ? "[c]" : "");
1365 sql_insert_return_states(return_id, return_ranges,
1366 func_gets_user_data ? USER_DATA_SET : USER_DATA,
1367 param, param_name, buf);
1368 } END_FOR_EACH_SM(sm);
1369
1370 /* This if for "return foo;" where "foo->bar" is user data. */
1371 FOR_EACH_MY_SM(my_id, __get_cur_stree(), sm) {
1372 if (!ret_sym)
1373 break;
1374 if (ret_sym != sm->sym)
1375 continue;
1376
1377 param_name = state_name_to_param_name(sm->name, return_str);
1378 if (!param_name)
1379 continue;
1380 if (strcmp(param_name, "$") == 0)
1381 return_found = true;
1382 if (strcmp(param_name, "*$") == 0)
1383 pointed_at_found = true;
1384 snprintf(buf, sizeof(buf), "%s%s",
1385 show_rl(estate_rl(sm->state)),
1386 estate_capped(sm->state) ? "[c]" : "");
1387 sql_insert_return_states(return_id, return_ranges,
1388 func_gets_user_data ? USER_DATA_SET : USER_DATA,
1389 -1, param_name, buf);
1390 } END_FOR_EACH_SM(sm);
1391
1392 /* This if for "return ntohl(foo);" */
1393 if (!return_found && get_user_rl(expr, &rl)) {
1394 snprintf(buf, sizeof(buf), "%s%s",
1395 show_rl(rl), user_rl_capped(expr) ? "[c]" : "");
1396 sql_insert_return_states(return_id, return_ranges,
1397 func_gets_user_data ? USER_DATA_SET : USER_DATA,
1398 -1, "$", buf);
1399 }
1400
1401 /*
1402 * This is to handle things like return skb->data where we don't set a
1403 * state for that.
1404 */
1405 if (!pointed_at_found && points_to_user_data(expr)) {
1406 sql_insert_return_states(return_id, return_ranges,
1407 (is_skb_data(expr) || func_gets_user_data) ?
1408 USER_DATA_SET : USER_DATA,
1409 -1, "*$", "s64min-s64max");
1410 }
1411
1412 free_string(return_str);
1413 }
1414
1415 static void returns_param_capped(struct expression *expr, int param, char *key, char *value)
1416 {
1417 struct smatch_state *state, *new;
1418 struct symbol *sym;
1419 char *name;
1420
1421 name = return_state_to_var_sym(expr, param, key, &sym);
1422 if (!name || !sym)
1423 goto free;
1424
1425 state = get_state(my_id, name, sym);
1426 if (!state || estate_capped(state))
1427 goto free;
1428
1429 new = clone_estate(state);
1430 estate_set_capped(new);
1431
1432 set_state(my_id, name, sym, new);
1433 free:
1434 free_string(name);
1435 }
1436
1437 static struct int_stack *gets_data_stack;
1438 static void match_function_def(struct symbol *sym)
1439 {
1440 func_gets_user_data = false;
1441 }
1442
1443 static void match_inline_start(struct expression *expr)
1444 {
1445 push_int(&gets_data_stack, func_gets_user_data);
1446 }
1447
1448 static void match_inline_end(struct expression *expr)
1449 {
1450 func_gets_user_data = pop_int(&gets_data_stack);
1451 }
1452
1453 void register_kernel_user_data(int id)
1454 {
1455 int i;
1456
1457 my_id = id;
1458
1459 if (option_project != PROJ_KERNEL)
1460 return;
1461
1462 set_dynamic_states(my_id);
1463
1464 add_hook(&match_function_def, FUNC_DEF_HOOK);
1465 add_hook(&match_inline_start, INLINE_FN_START);
1466 add_hook(&match_inline_end, INLINE_FN_END);
1467
1468 add_hook(&save_start_states, AFTER_DEF_HOOK);
1469 add_hook(&free_start_states, AFTER_FUNC_HOOK);
1470 add_hook(&match_save_states, INLINE_FN_START);
1471 add_hook(&match_restore_states, INLINE_FN_END);
1472
1473 add_unmatched_state_hook(my_id, &empty_state);
1474 add_extra_nomod_hook(&extra_nomod_hook);
1475 add_pre_merge_hook(my_id, &pre_merge_hook);
1476 add_merge_hook(my_id, &merge_estates);
1477
1478 add_function_hook("copy_from_user", &match_user_copy, INT_PTR(0));
1479 add_function_hook("__copy_from_user", &match_user_copy, INT_PTR(0));
1480 add_function_hook("memcpy_fromiovec", &match_user_copy, INT_PTR(0));
1481 for (i = 0; i < ARRAY_SIZE(kstr_funcs); i++)
1482 add_function_hook(kstr_funcs[i], &match_user_copy, INT_PTR(2));
1483 add_function_hook("usb_control_msg", &match_user_copy, INT_PTR(6));
1484
1485 for (i = 0; i < ARRAY_SIZE(returns_user_data); i++) {
1486 add_function_assign_hook(returns_user_data[i], &match_user_assign_function, NULL);
1487 add_function_hook(returns_user_data[i], &match_returns_user_rl, NULL);
1488 }
1489
1490 add_function_hook("sscanf", &match_sscanf, NULL);
1491
1492 add_hook(&match_syscall_definition, AFTER_DEF_HOOK);
1493
1494 add_hook(&match_assign, ASSIGNMENT_HOOK);
1495 select_return_states_hook(PARAM_SET, &db_param_set);
1496 add_hook(&match_condition, CONDITION_HOOK);
1497
1498 add_hook(&match_call_info, FUNCTION_CALL_HOOK);
1499 add_member_info_callback(my_id, struct_member_callback);
1500 select_caller_info_hook(set_param_user_data, USER_DATA);
1501 select_return_states_hook(USER_DATA, &returns_param_user_data);
1502 select_return_states_hook(USER_DATA_SET, &returns_param_user_data_set);
1503 select_return_states_hook(CAPPED_DATA, &returns_param_capped);
1504 add_split_return_callback(¶m_set_to_user_data);
1505 }
1506
1507 void register_kernel_user_data2(int id)
1508 {
1509 my_call_id = id;
1510
1511 if (option_project != PROJ_KERNEL)
1512 return;
1513 select_caller_info_hook(set_called, INTERNAL);
1514 }