1 /*
2 * Copyright (C) 2014 Oracle.
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 * Sometimes we aren't able to track a variable through a function call. This
20 * usually happens because a function changes too many variables so we give up.
21 * Another reason this happens is because we call a function pointer and there
22 * are too many functions which implement that function pointer so we give up.
23 * Also maybe we don't have the database enabled.
24 *
25 * The goal here is to make a call back so what if we call:
26 *
27 * frob(&foo);
28 *
29 * but we're not able to say what happens to "foo", then let's assume that we
30 * don't know anything about "foo" if it's an untracked call.
31 *
32 */
33
34 #include "smatch.h"
35 #include "smatch_slist.h"
36 #include "smatch_extra.h"
37
38 static int my_id;
39 static int tracked;
40
41 STATE(untracked);
42
43 typedef void (untracked_hook)(struct expression *call, int param);
44 DECLARE_PTR_LIST(untracked_hook_list, untracked_hook *);
45 static struct untracked_hook_list *untracked_hooks;
46
47 struct int_stack *tracked_stack;
48
49 void add_untracked_param_hook(void (func)(struct expression *call, int param))
50 {
51 untracked_hook **p = malloc(sizeof(untracked_hook *));
52 *p = func;
53 add_ptr_list(&untracked_hooks, p);
54 }
55
56 static void call_untracked_callbacks(struct expression *expr, int param)
57 {
58 untracked_hook **fn;
59
60 FOR_EACH_PTR(untracked_hooks, fn) {
61 (*fn)(expr, param);
62 } END_FOR_EACH_PTR(fn);
63 }
64
65 static void assume_tracked(struct expression *call_expr, int param, char *key, char *value)
66 {
67 tracked = 1;
68 }
69
70 void mark_untracked(struct expression *expr, int param, const char *key, const char *value)
71 {
72 char *name;
73 struct symbol *sym;
74
75 while (expr->type == EXPR_ASSIGNMENT)
76 expr = strip_expr(expr->right);
77 if (expr->type != EXPR_CALL)
78 return;
79
80 name = return_state_to_var_sym(expr, param, key, &sym);
81 if (!name || !sym)
82 goto free;
83
84 call_untracked_callbacks(expr, param);
85 set_state(my_id, name, sym, &untracked);
86 free:
87 free_string(name);
88 }
89
90 static int lost_in_va_args(struct expression *expr)
91 {
92 struct symbol *fn;
93 char *name;
94 int is_lost;
95
96 fn = get_type(expr->fn);
97 if (!fn || !fn->variadic)
98 return 0;
99
100 is_lost = 1;
101 name = expr_to_var(expr->fn);
102 if (name && strstr(name, "print"))
103 is_lost = 0;
104 free_string(name);
105
106 return is_lost;
107 }
108
109 static void match_after_call(struct expression *expr)
110 {
111 struct expression *arg;
112 struct symbol *type;
113 int i;
114
115 if (lost_in_va_args(expr))
116 tracked = 0;
117
118 if (tracked) {
119 tracked = 0;
120 return;
121 }
122
123 i = -1;
124 FOR_EACH_PTR(expr->args, arg) {
125 i++;
126
127 type = get_type(arg);
128 if (!type || type->type != SYM_PTR)
129 continue;
130
131 call_untracked_callbacks(expr, i);
132 set_state_expr(my_id, arg, &untracked);
133 } END_FOR_EACH_PTR(arg);
134 }
135
136 void mark_all_params_untracked(int return_id, char *return_ranges, struct expression *expr)
137 {
138 struct symbol *arg;
139 int param;
140
141 param = -1;
142 FOR_EACH_PTR(cur_func_sym->ctype.base_type->arguments, arg) {
143 param++;
144
145 if (!arg->ident)
146 continue;
147 sql_insert_return_states(return_id, return_ranges,
148 UNTRACKED_PARAM, param, "$", "");
149 } END_FOR_EACH_PTR(arg);
150 }
151
152 static void print_untracked_params(int return_id, char *return_ranges, struct expression *expr)
153 {
154 struct symbol *arg;
155 int param;
156
157 param = -1;
158 FOR_EACH_PTR(cur_func_sym->ctype.base_type->arguments, arg) {
159 param++;
160
161 if (!arg->ident)
162 continue;
163 if (!get_state(my_id, arg->ident->name, arg) &&
164 !__bail_on_rest_of_function) /* hairy functions are untrackable */
165 continue;
166
167 sql_insert_return_states(return_id, return_ranges,
168 UNTRACKED_PARAM, param, "$", "");
169 } END_FOR_EACH_PTR(arg);
170 }
171
172 static void match_param_assign(struct expression *expr)
173 {
174 struct expression *right;
175 struct symbol *type;
176 int param;
177
178 if (__in_fake_assign)
179 return;
180
181 right = strip_expr(expr->right);
182 type = get_type(right);
183 if (!type || type->type != SYM_PTR)
184 return;
185
186 param = get_param_num(right);
187 if (param < 0)
188 return;
189
190 set_state_expr(my_id, right, &untracked);
191 }
192
193
194 static void match_param_assign_in_asm(struct statement *stmt)
195 {
196
197 struct expression *expr;
198 struct symbol *type;
199 int state = 0;
200 int param;
201
202 FOR_EACH_PTR(stmt->asm_inputs, expr) {
203 switch (state) {
204 case 0: /* identifier */
205 case 1: /* constraint */
206 state++;
207 continue;
208 case 2: /* expression */
209 state = 0;
210
211 expr = strip_expr(expr);
212 type = get_type(expr);
213 if (!type || type->type != SYM_PTR)
214 continue;
215 param = get_param_num(expr);
216 if (param < 0)
217 continue;
218 set_state_expr(my_id, expr, &untracked);
219 continue;
220 }
221 } END_FOR_EACH_PTR(expr);
222 }
223
224 static void match_inline_start(struct expression *expr)
225 {
226 push_int(&tracked_stack, tracked);
227 }
228
229 static void match_inline_end(struct expression *expr)
230 {
231 tracked = pop_int(&tracked_stack);
232 }
233
234 void register_untracked_param(int id)
235 {
236 my_id = id;
237
238 select_return_states_hook(INTERNAL, &assume_tracked);
239 select_return_states_hook(UNTRACKED_PARAM, &mark_untracked);
240 add_hook(&match_after_call, FUNCTION_CALL_HOOK_AFTER_DB);
241
242 add_split_return_callback(&print_untracked_params);
243
244 add_hook(&match_param_assign, ASSIGNMENT_HOOK);
245 add_hook(&match_param_assign_in_asm, ASM_HOOK);
246
247 add_hook(&match_inline_start, INLINE_FN_START);
248 add_hook(&match_inline_end, INLINE_FN_END);
249 }