1 | /* Copyright (C) 2013-2023 Free Software Foundation, Inc. |
2 | |
3 | This file is part of GCC. |
4 | |
5 | GCC is free software; you can redistribute it and/or modify it under |
6 | the terms of the GNU General Public License as published by the Free |
7 | Software Foundation; either version 3, or (at your option) any later |
8 | version. |
9 | |
10 | GCC is distributed in the hope that it will be useful, but WITHOUT ANY |
11 | WARRANTY; without even the implied warranty of MERCHANTABILITY or |
12 | FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
13 | for more details. |
14 | |
15 | You should have received a copy of the GNU General Public License |
16 | along with GCC; see the file COPYING3. If not see |
17 | <http://www.gnu.org/licenses/>. */ |
18 | |
19 | /* Virtual Table Pointer Security. */ |
20 | |
21 | #ifndef VTABLE_VERIFY_H |
22 | #define VTABLE_VERIFY_H |
23 | |
24 | #include "sbitmap.h" |
25 | |
26 | /* The function decl used to create calls to __VLTVtableVerify. It must |
27 | be global because it needs to be initialized in the C++ front end, but |
28 | used in the middle end (in the vtable verification pass). */ |
29 | |
30 | extern tree verify_vtbl_ptr_fndecl; |
31 | |
32 | /* Global variable keeping track of how many vtable map variables we |
33 | have created. */ |
34 | extern unsigned num_vtable_map_nodes; |
35 | |
36 | /* Keep track of how many virtual calls we are actually verifying. */ |
37 | extern int total_num_virtual_calls; |
38 | extern int total_num_verified_vcalls; |
39 | |
40 | /* Each vtable map variable corresponds to a virtual class. Each |
41 | vtable map variable has a hash table associated with it, that keeps |
42 | track of the vtable pointers for which we have generated a call to |
43 | __VLTRegisterPair (with the current vtable map variable). This is |
44 | the hash table node that is used for each entry in this hash table |
45 | of vtable pointers. |
46 | |
47 | Sometimes there are multiple valid vtable pointer entries that use |
48 | the same vtable pointer decl with different offsets. Therefore, |
49 | for each vtable pointer in the hash table, there is also an array |
50 | of offsets used with that vtable. */ |
51 | |
52 | struct vtable_registration |
53 | { |
54 | tree vtable_decl; /* The var decl of the vtable. */ |
55 | vec<unsigned> offsets; /* The offsets array. */ |
56 | }; |
57 | |
58 | struct registration_hasher : nofree_ptr_hash <struct vtable_registration> |
59 | { |
60 | static inline hashval_t hash (const vtable_registration *); |
61 | static inline bool equal (const vtable_registration *, |
62 | const vtable_registration *); |
63 | }; |
64 | |
65 | typedef hash_table<registration_hasher> register_table_type; |
66 | typedef register_table_type::iterator registration_iterator_type; |
67 | |
68 | /* This struct is used to represent the class hierarchy information |
69 | that we need. Each vtable map variable has an associated class |
70 | hierarchy node (struct vtv_graph_node). Note: In this struct, |
71 | 'children' means immediate descendants in the class hierarchy; |
72 | 'descendant' means any descendant however many levels deep. */ |
73 | |
74 | struct vtv_graph_node { |
75 | tree class_type; /* The record_type of the class. */ |
76 | unsigned class_uid; /* A unique, monotonically |
77 | ascending id for class node. |
78 | Each vtable map node also has |
79 | an id. The class uid is the |
80 | same as the vtable map node id |
81 | for nodes corresponding to the |
82 | same class. */ |
83 | unsigned num_processed_children; /* # of children for whom we have |
84 | computed the class hierarchy |
85 | transitive closure. */ |
86 | vec<struct vtv_graph_node *> parents; /* Vector of parents in the graph. */ |
87 | vec<struct vtv_graph_node *> children; /* Vector of children in the graph.*/ |
88 | sbitmap descendants; /* Bitmap representing all this node's |
89 | descendants in the graph. */ |
90 | }; |
91 | |
92 | /* This is the node used for our hashtable of vtable map variable |
93 | information. When we create a vtable map variable (var decl) we |
94 | put it into one of these nodes; create a corresponding |
95 | vtv_graph_node for our class hierarchy info and store that in this |
96 | node; generate a unique (monotonically ascending) id for both the |
97 | vtbl_map_node and the vtv_graph_node; and insert the node into two |
98 | data structures (to make it easy to find in several different |
99 | ways): 1). A hash table ("vtbl_map_hash" in vtable-verify.cc). |
100 | This gives us an easy way to check to see if we already have a node |
101 | for the vtable map variable or not; and 2). An array (vector) of |
102 | vtbl_map_nodes, where the array index corresponds to the unique id |
103 | of the vtbl_map_node, which gives us an easy way to use bitmaps to |
104 | represent and find the vtable map nodes. */ |
105 | |
106 | struct vtbl_map_node { |
107 | tree vtbl_map_decl; /* The var decl for the vtable map |
108 | variable. */ |
109 | tree class_name; /* The DECL_ASSEMBLER_NAME of the |
110 | class. */ |
111 | struct vtv_graph_node *class_info; /* Our class hierarchy info for the |
112 | class. */ |
113 | unsigned uid; /* The unique id for the vtable map |
114 | variable. */ |
115 | struct vtbl_map_node *next, *prev; /* Pointers for the linked list |
116 | structure. */ |
117 | register_table_type *registered; /* Hashtable of vtable pointers for which |
118 | we have generated a _VLTRegisterPair |
119 | call with this vtable map variable. */ |
120 | bool is_used; /* Boolean indicating if we used this vtable map |
121 | variable in a call to __VLTVerifyVtablePointer. */ |
122 | }; |
123 | |
124 | /* Controls debugging for vtable verification. */ |
125 | extern bool vtv_debug; |
126 | |
127 | /* The global vector of vtbl_map_nodes. */ |
128 | extern vec<struct vtbl_map_node *> vtbl_map_nodes_vec; |
129 | |
130 | /* The global vectors for mangled class names for anonymous classes. */ |
131 | extern GTY(()) vec<tree, va_gc> *vtbl_mangled_name_types; |
132 | extern GTY(()) vec<tree, va_gc> *vtbl_mangled_name_ids; |
133 | |
134 | extern void vtbl_register_mangled_name (tree, tree); |
135 | extern struct vtbl_map_node *vtbl_map_get_node (tree); |
136 | extern struct vtbl_map_node *find_or_create_vtbl_map_node (tree); |
137 | extern void vtbl_map_node_class_insert (struct vtbl_map_node *, unsigned); |
138 | extern bool vtbl_map_node_registration_find (struct vtbl_map_node *, |
139 | tree, unsigned); |
140 | extern bool vtbl_map_node_registration_insert (struct vtbl_map_node *, |
141 | tree, unsigned); |
142 | |
143 | #endif /* VTABLE_VERIFY_H */ |
144 | |