1 /* Copyright (C) 2013-2018 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.c). 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