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 STATE(lost);
43
44 typedef void (untracked_hook)(struct expression *call, int param);
45 DECLARE_PTR_LIST(untracked_hook_list, untracked_hook *);
46 static struct untracked_hook_list *untracked_hooks;
47 static struct untracked_hook_list *lost_hooks;
48
49 struct int_stack *tracked_stack;
50
51 void add_untracked_param_hook(void (func)(struct expression *call, int param))
52 {
53 untracked_hook **p = malloc(sizeof(untracked_hook *));
54 *p = func;
55 add_ptr_list(&untracked_hooks, p);
56 }
57
58 static void call_untracked_callbacks(struct expression *expr, int param)
59 {
60 untracked_hook **fn;
61
62 FOR_EACH_PTR(untracked_hooks, fn) {
63 (*fn)(expr, param);
64 } END_FOR_EACH_PTR(fn);
65 }
66
67 void add_lost_param_hook(void (func)(struct expression *call, int param))
68 {
69 untracked_hook **p = malloc(sizeof(untracked_hook *));
70 *p = func;
71 add_ptr_list(&lost_hooks, p);
72 }
73
74 static void call_lost_callbacks(struct expression *expr, int param)
75 {
76 untracked_hook **fn;
77
78 FOR_EACH_PTR(lost_hooks, fn) {
79 (*fn)(expr, param);
80 } END_FOR_EACH_PTR(fn);
81 }
82
83 static void assume_tracked(struct expression *call_expr, int param, char *key, char *value)
84 {
85 tracked = 1;
86 }
87
88 static char *get_array_from_key(struct expression *expr, int param, const char *key, struct symbol **sym)
89 {
90 struct expression *arg;
91
92 arg = get_argument_from_call_expr(expr->args, param);
93 if (!arg)
94 return NULL;
95 if (arg->type != EXPR_PREOP || arg->op != '&')
96 return NULL;
97 arg = arg->unop;
98 if (!is_array(arg))
99 return NULL;
100 arg = get_array_base(arg);
101
102 return expr_to_var_sym(arg, sym);
103 }
104
105 static void mark_untracked_lost(struct expression *expr, int param, const char *key, int type)
106 {
107 char *name;
108 struct symbol *sym;
109
110 while (expr->type == EXPR_ASSIGNMENT)
111 expr = strip_expr(expr->right);
112 if (expr->type != EXPR_CALL)
113 return;
114
115 name = return_state_to_var_sym(expr, param, key, &sym);
116 if (!name || !sym) {
117 name = get_array_from_key(expr, param, key, &sym);
118 if (!name || !sym)
119 goto free;
120 }
121
122 if (type == LOST_PARAM)
123 call_lost_callbacks(expr, param);
124 call_untracked_callbacks(expr, param);
125 set_state(my_id, name, sym, &untracked);
126 free:
127 free_string(name);
128
129 }
130
131 void mark_untracked(struct expression *expr, int param, const char *key, const char *value)
132 {
133 mark_untracked_lost(expr, param, key, UNTRACKED_PARAM);
134 }
135
136 void mark_lost(struct expression *expr, int param, const char *key, const char *value)
137 {
138 mark_untracked_lost(expr, param, key, LOST_PARAM);
139 }
140
141 static int lost_in_va_args(struct expression *expr)
142 {
143 struct symbol *fn;
144 char *name;
145 int is_lost;
146
147 fn = get_type(expr->fn);
148 if (!fn || !fn->variadic)
149 return 0;
150
151 is_lost = 1;
152 name = expr_to_var(expr->fn);
153 if (name && strstr(name, "print"))
154 is_lost = 0;
155 free_string(name);
156
157 return is_lost;
158 }
159
160 static void match_after_call(struct expression *expr)
161 {
162 struct expression *arg;
163 struct symbol *type;
164 int i;
165
166 if (lost_in_va_args(expr))
167 tracked = 0;
168
169 if (tracked) {
170 tracked = 0;
171 return;
172 }
173
174 i = -1;
175 FOR_EACH_PTR(expr->args, arg) {
176 i++;
177
178 type = get_type(arg);
179 if (!type || type->type != SYM_PTR)
180 continue;
181
182 call_untracked_callbacks(expr, i);
183 set_state_expr(my_id, arg, &untracked);
184 } END_FOR_EACH_PTR(arg);
185 }
186
187
188 static void mark_all_params(int return_id, char *return_ranges, int type)
189 {
190 struct symbol *arg;
191 int param;
192
193 param = -1;
194 FOR_EACH_PTR(cur_func_sym->ctype.base_type->arguments, arg) {
195 param++;
196
197 if (!arg->ident)
198 continue;
199 sql_insert_return_states(return_id, return_ranges,
200 type, param, "$", "");
201 } END_FOR_EACH_PTR(arg);
202 }
203
204
205 void mark_all_params_untracked(int return_id, char *return_ranges, struct expression *expr)
206 {
207 mark_all_params(return_id, return_ranges, UNTRACKED_PARAM);
208 }
209
210 void mark_all_params_lost(int return_id, char *return_ranges, struct expression *expr)
211 {
212 mark_all_params(return_id, return_ranges, LOST_PARAM);
213 }
214
215 static void print_untracked_params(int return_id, char *return_ranges, struct expression *expr)
216 {
217 struct sm_state *sm;
218 struct symbol *arg;
219 int param;
220 int type;
221
222 param = -1;
223 FOR_EACH_PTR(cur_func_sym->ctype.base_type->arguments, arg) {
224 param++;
225
226 if (!arg->ident)
227 continue;
228
229 if (__bail_on_rest_of_function) {
230 /* hairy functions are lost */
231 type = LOST_PARAM;
232 } else if ((sm = get_sm_state(my_id, arg->ident->name, arg))) {
233 if (slist_has_state(sm->possible, &lost))
234 type = LOST_PARAM;
235 else
236 type = UNTRACKED_PARAM;
237 } else {
238 continue;
239 }
240
241 sql_insert_return_states(return_id, return_ranges,
242 type, param, "$", "");
243 } END_FOR_EACH_PTR(arg);
244 }
245
246 static void match_param_assign(struct expression *expr)
247 {
248 struct expression *right;
249 struct symbol *type;
250 int param;
251
252 if (__in_fake_assign)
253 return;
254
255 right = strip_expr(expr->right);
256 type = get_type(right);
257 if (!type || type->type != SYM_PTR)
258 return;
259
260 param = get_param_num(right);
261 if (param < 0)
262 return;
263
264 set_state_expr(my_id, right, &untracked);
265 }
266
267
268 static void match_param_assign_in_asm(struct statement *stmt)
269 {
270
271 struct expression *tmp, *expr;
272 struct symbol *type;
273 int param;
274
275 FOR_EACH_PTR(stmt->asm_inputs, tmp) {
276 expr = strip_expr(tmp->expr);
277 type = get_type(expr);
278 if (!type || type->type != SYM_PTR)
279 continue;
280 param = get_param_num(expr);
281 if (param < 0)
282 continue;
283 set_state_expr(my_id, expr, &untracked);
284 } END_FOR_EACH_PTR(tmp);
285 }
286
287 static void match_inline_start(struct expression *expr)
288 {
289 push_int(&tracked_stack, tracked);
290 }
291
292 static void match_inline_end(struct expression *expr)
293 {
294 tracked = pop_int(&tracked_stack);
295 }
296
297 void register_untracked_param(int id)
298 {
299 my_id = id;
300
301 select_return_states_hook(INTERNAL, &assume_tracked);
302 select_return_states_hook(UNTRACKED_PARAM, &mark_untracked);
303 select_return_states_hook(LOST_PARAM, &mark_lost);
304 add_hook(&match_after_call, FUNCTION_CALL_HOOK_AFTER_DB);
305
306 add_split_return_callback(&print_untracked_params);
307
308 add_hook(&match_param_assign, ASSIGNMENT_HOOK);
309 add_hook(&match_param_assign_in_asm, ASM_HOOK);
310
311 add_hook(&match_inline_start, INLINE_FN_START);
312 add_hook(&match_inline_end, INLINE_FN_END);
313 }