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757bf1df | 1 | /* Modeling API uses and misuses via state machines. |
99dee823 | 2 | Copyright (C) 2019-2021 Free Software Foundation, Inc. |
757bf1df DM |
3 | Contributed by David Malcolm <dmalcolm@redhat.com>. |
4 | ||
5 | This file is part of GCC. | |
6 | ||
7 | GCC is free software; you can redistribute it and/or modify it | |
8 | under the terms of the GNU General Public License as published by | |
9 | the Free Software Foundation; either version 3, or (at your option) | |
10 | any later version. | |
11 | ||
12 | GCC is distributed in the hope that it will be useful, but | |
13 | WITHOUT ANY WARRANTY; without even the implied warranty of | |
14 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
15 | General Public License for more details. | |
16 | ||
17 | You should have received a copy of the GNU General Public License | |
18 | along with GCC; see the file COPYING3. If not see | |
19 | <http://www.gnu.org/licenses/>. */ | |
20 | ||
21 | #ifndef GCC_ANALYZER_SM_H | |
22 | #define GCC_ANALYZER_SM_H | |
23 | ||
24 | /* Utility functions for use by state machines. */ | |
25 | ||
75038aa6 DM |
26 | namespace ana { |
27 | ||
757bf1df DM |
28 | class state_machine; |
29 | class sm_context; | |
30 | class pending_diagnostic; | |
31 | ||
808f4dfe DM |
32 | extern bool any_pointer_p (tree var); |
33 | ||
757bf1df | 34 | /* An abstract base class for a state machine describing an API. |
10fc42a8 | 35 | Manages a set of state objects, and has various virtual functions |
757bf1df DM |
36 | for pattern-matching on statements. */ |
37 | ||
38 | class state_machine : public log_user | |
39 | { | |
40 | public: | |
10fc42a8 DM |
41 | /* States are represented by immutable objects, owned by the state |
42 | machine. */ | |
43 | class state | |
44 | { | |
45 | public: | |
46 | state (const char *name, unsigned id) : m_name (name), m_id (id) {} | |
47 | virtual ~state () {} | |
48 | ||
49 | const char *get_name () const { return m_name; } | |
50 | virtual void dump_to_pp (pretty_printer *pp) const; | |
809192e7 | 51 | virtual json::value *to_json () const; |
10fc42a8 DM |
52 | |
53 | unsigned get_id () const { return m_id; } | |
757bf1df | 54 | |
10fc42a8 DM |
55 | private: |
56 | const char *m_name; | |
57 | unsigned m_id; | |
58 | }; | |
59 | typedef const state_machine::state *state_t; | |
757bf1df | 60 | |
10fc42a8 | 61 | state_machine (const char *name, logger *logger); |
757bf1df DM |
62 | virtual ~state_machine () {} |
63 | ||
64 | /* Should states be inherited from a parent region to a child region, | |
65 | when first accessing a child region? | |
66 | For example we should inherit the taintedness of a subregion, | |
67 | but we should not inherit the "malloc:non-null" state of a field | |
68 | within a heap-allocated struct. */ | |
69 | virtual bool inherited_state_p () const = 0; | |
70 | ||
808f4dfe DM |
71 | virtual state_machine::state_t get_default_state (const svalue *) const |
72 | { | |
10fc42a8 | 73 | return m_start; |
808f4dfe DM |
74 | } |
75 | ||
757bf1df DM |
76 | const char *get_name () const { return m_name; } |
77 | ||
10fc42a8 | 78 | state_t get_state_by_name (const char *name) const; |
41f99ba6 | 79 | |
757bf1df DM |
80 | /* Return true if STMT is a function call recognized by this sm. */ |
81 | virtual bool on_stmt (sm_context *sm_ctxt, | |
82 | const supernode *node, | |
83 | const gimple *stmt) const = 0; | |
84 | ||
8525d1f5 DM |
85 | virtual void on_phi (sm_context *sm_ctxt ATTRIBUTE_UNUSED, |
86 | const supernode *node ATTRIBUTE_UNUSED, | |
87 | const gphi *phi ATTRIBUTE_UNUSED, | |
88 | tree rhs ATTRIBUTE_UNUSED) const | |
89 | { | |
90 | } | |
91 | ||
757bf1df DM |
92 | virtual void on_condition (sm_context *sm_ctxt, |
93 | const supernode *node, | |
94 | const gimple *stmt, | |
95 | tree lhs, enum tree_code op, tree rhs) const = 0; | |
96 | ||
97 | /* Return true if it safe to discard the given state (to help | |
98 | when simplifying state objects). | |
99 | States that need leak detection should return false. */ | |
100 | virtual bool can_purge_p (state_t s) const = 0; | |
101 | ||
102 | /* Called when VAR leaks (and !can_purge_p). */ | |
103 | virtual pending_diagnostic *on_leak (tree var ATTRIBUTE_UNUSED) const | |
104 | { | |
105 | return NULL; | |
106 | } | |
107 | ||
808f4dfe DM |
108 | /* Return true if S should be reset to "start" for values passed (or reachable |
109 | from) calls to unknown functions. IS_MUTABLE is true for pointers as | |
110 | non-const, false if only passed as const-pointers. | |
111 | ||
112 | For example, in sm-malloc.cc, an on-stack ptr doesn't stop being | |
113 | stack-allocated when passed to an unknown fn, but a malloc-ed pointer | |
114 | could be freed when passed to an unknown fn (unless passed as "const"). */ | |
115 | virtual bool reset_when_passed_to_unknown_fn_p (state_t s ATTRIBUTE_UNUSED, | |
116 | bool is_mutable) const | |
117 | { | |
118 | return is_mutable; | |
119 | } | |
120 | ||
757bf1df DM |
121 | void validate (state_t s) const; |
122 | ||
42f36563 DM |
123 | void dump_to_pp (pretty_printer *pp) const; |
124 | ||
809192e7 DM |
125 | json::object *to_json () const; |
126 | ||
10fc42a8 DM |
127 | state_t get_start_state () const { return m_start; } |
128 | ||
757bf1df DM |
129 | protected: |
130 | state_t add_state (const char *name); | |
1690a839 DM |
131 | state_t add_custom_state (state *s) |
132 | { | |
133 | m_states.safe_push (s); | |
134 | return s; | |
135 | } | |
136 | ||
10fc42a8 | 137 | unsigned alloc_state_id () { return m_next_state_id++; } |
757bf1df DM |
138 | |
139 | private: | |
140 | DISABLE_COPY_AND_ASSIGN (state_machine); | |
141 | ||
142 | const char *m_name; | |
757bf1df | 143 | |
10fc42a8 DM |
144 | /* States are owned by the state_machine. */ |
145 | auto_delete_vec<state> m_states; | |
757bf1df | 146 | |
10fc42a8 DM |
147 | unsigned m_next_state_id; |
148 | ||
149 | protected: | |
150 | /* Must be inited after m_next_state_id. */ | |
151 | state_t m_start; | |
152 | }; | |
757bf1df DM |
153 | |
154 | /* Abstract base class for state machines to pass to | |
155 | sm_context::on_custom_transition for handling non-standard transitions | |
156 | (e.g. adding a node and edge to simulate registering a callback and having | |
157 | the callback be called later). */ | |
158 | ||
159 | class custom_transition | |
160 | { | |
161 | public: | |
162 | virtual ~custom_transition () {} | |
163 | virtual void impl_transition (exploded_graph *eg, | |
164 | exploded_node *src_enode, | |
165 | int sm_idx) = 0; | |
166 | }; | |
167 | ||
168 | /* Abstract base class giving an interface for the state machine to call | |
169 | the checker engine, at a particular stmt. */ | |
170 | ||
171 | class sm_context | |
172 | { | |
173 | public: | |
174 | virtual ~sm_context () {} | |
175 | ||
176 | /* Get the fndecl used at call, or NULL_TREE. | |
177 | Use in preference to gimple_call_fndecl (and gimple_call_addr_fndecl), | |
178 | since it can look through function pointer assignments and | |
179 | other callback handling. */ | |
180 | virtual tree get_fndecl_for_call (const gcall *call) = 0; | |
181 | ||
6d9ca8c8 DM |
182 | /* Get the old state of VAR at STMT. */ |
183 | virtual state_machine::state_t get_state (const gimple *stmt, | |
184 | tree var) = 0; | |
185 | /* Set the next state of VAR to be TO, recording the "origin" of the | |
186 | state as ORIGIN. | |
187 | Use STMT for location information. */ | |
188 | virtual void set_next_state (const gimple *stmt, | |
189 | tree var, | |
190 | state_machine::state_t to, | |
191 | tree origin = NULL_TREE) = 0; | |
192 | ||
757bf1df DM |
193 | /* Called by state_machine in response to pattern matches: |
194 | if VAR is in state FROM, transition it to state TO, potentially | |
195 | recording the "origin" of the state as ORIGIN. | |
196 | Use NODE and STMT for location information. */ | |
6d9ca8c8 DM |
197 | void on_transition (const supernode *node ATTRIBUTE_UNUSED, |
198 | const gimple *stmt, | |
199 | tree var, | |
200 | state_machine::state_t from, | |
201 | state_machine::state_t to, | |
202 | tree origin = NULL_TREE) | |
203 | { | |
204 | state_machine::state_t current = get_state (stmt, var); | |
205 | if (current == from) | |
206 | set_next_state (stmt, var, to, origin); | |
207 | } | |
757bf1df DM |
208 | |
209 | /* Called by state_machine in response to pattern matches: | |
25ef215a DM |
210 | issue a diagnostic D using NODE and STMT for location information. */ |
211 | virtual void warn (const supernode *node, const gimple *stmt, | |
212 | tree var, pending_diagnostic *d) = 0; | |
757bf1df | 213 | |
808f4dfe DM |
214 | /* For use when generating trees when creating pending_diagnostics, so that |
215 | rather than e.g. | |
216 | "double-free of '<unknown>'" | |
217 | we can print: | |
218 | "double-free of 'inbuf.data'". */ | |
219 | virtual tree get_diagnostic_tree (tree expr) | |
757bf1df DM |
220 | { |
221 | return expr; | |
222 | } | |
223 | ||
224 | virtual state_machine::state_t get_global_state () const = 0; | |
225 | virtual void set_global_state (state_machine::state_t) = 0; | |
226 | ||
227 | /* A vfunc for handling custom transitions, such as when registering | |
228 | a signal handler. */ | |
229 | virtual void on_custom_transition (custom_transition *transition) = 0; | |
230 | ||
808f4dfe DM |
231 | /* If STMT is an assignment known to assign zero to its LHS, return |
232 | the LHS. | |
233 | Otherwise return NULL_TREE. */ | |
234 | virtual tree is_zero_assignment (const gimple *stmt) = 0; | |
235 | ||
757bf1df DM |
236 | protected: |
237 | sm_context (int sm_idx, const state_machine &sm) | |
238 | : m_sm_idx (sm_idx), m_sm (sm) {} | |
239 | ||
240 | int m_sm_idx; | |
241 | const state_machine &m_sm; | |
242 | }; | |
243 | ||
244 | ||
245 | /* The various state_machine subclasses are hidden in their respective | |
246 | implementation files. */ | |
247 | ||
248 | extern void make_checkers (auto_delete_vec <state_machine> &out, | |
249 | logger *logger); | |
250 | ||
251 | extern state_machine *make_malloc_state_machine (logger *logger); | |
252 | extern state_machine *make_fileptr_state_machine (logger *logger); | |
253 | extern state_machine *make_taint_state_machine (logger *logger); | |
254 | extern state_machine *make_sensitive_state_machine (logger *logger); | |
255 | extern state_machine *make_signal_state_machine (logger *logger); | |
256 | extern state_machine *make_pattern_test_state_machine (logger *logger); | |
257 | ||
75038aa6 DM |
258 | } // namespace ana |
259 | ||
757bf1df | 260 | #endif /* GCC_ANALYZER_SM_H */ |