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 */