gcc/asan.h

   1 /* AddressSanitizer, a fast memory error detector.
   2    Copyright (C) 2011-2020 Free Software Foundation, Inc.
   3    Contributed by Kostya Serebryany <kcc@google.com>
   4
   5 This file is part of GCC.
   6
   7 GCC is free software; you can redistribute it and/or modify it under
   8 the terms of the GNU General Public License as published by the Free
   9 Software Foundation; either version 3, or (at your option) any later
  10 version.
  11
  12 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  13 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  14 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  15 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 TREE_ASAN
  22 #define TREE_ASAN
  23
  24 extern void asan_function_start (void);
  25 extern void asan_finish_file (void);
  26 extern rtx_insn *asan_emit_stack_protection (rtx, rtx, unsigned int,
  27                                              HOST_WIDE_INT *, tree *, int);
  28 extern rtx_insn *asan_emit_allocas_unpoison (rtx, rtx, rtx_insn *);
  29 extern bool asan_protect_global (tree, bool ignore_decl_rtl_set_p = false);
  30 extern void initialize_sanitizer_builtins (void);
  31 extern tree asan_dynamic_init_call (bool);
  32 extern bool asan_expand_check_ifn (gimple_stmt_iterator *, bool);
  33 extern bool asan_expand_mark_ifn (gimple_stmt_iterator *);
  34 extern bool asan_expand_poison_ifn (gimple_stmt_iterator *, bool *,
  35                                     hash_map<tree, tree> &);
  36
  37 extern gimple_stmt_iterator create_cond_insert_point
  38      (gimple_stmt_iterator *, bool, bool, bool, basic_block *, basic_block *);
  39
  40 /* Alias set for accessing the shadow memory.  */
  41 extern alias_set_type asan_shadow_set;
  42
  43 /* Hash set of labels that are either used in a goto, or their address
  44    has been taken.  */
  45 extern hash_set <tree> *asan_used_labels;
  46
  47 /* Shadow memory is found at
  48    (address >> ASAN_SHADOW_SHIFT) + asan_shadow_offset ().  */
  49 #define ASAN_SHADOW_SHIFT       3
  50 #define ASAN_SHADOW_GRANULARITY (1UL << ASAN_SHADOW_SHIFT)
  51
  52 /* Red zone size, stack and global variables are padded by ASAN_RED_ZONE_SIZE
  53    up to 2 * ASAN_RED_ZONE_SIZE - 1 bytes.  */
  54 #define ASAN_RED_ZONE_SIZE      32
  55
  56 /* Stack variable use more compact red zones.  The size includes also
  57    size of variable itself.  */
  58
  59 #define ASAN_MIN_RED_ZONE_SIZE  16
  60
  61 /* Shadow memory values for stack protection.  Left is below protected vars,
  62    the first pointer in stack corresponding to that offset contains
  63    ASAN_STACK_FRAME_MAGIC word, the second pointer to a string describing
  64    the frame.  Middle is for padding in between variables, right is
  65    above the last protected variable and partial immediately after variables
  66    up to ASAN_RED_ZONE_SIZE alignment.  */
  67 #define ASAN_STACK_MAGIC_LEFT             0xf1
  68 #define ASAN_STACK_MAGIC_MIDDLE           0xf2
  69 #define ASAN_STACK_MAGIC_RIGHT            0xf3
  70 #define ASAN_STACK_MAGIC_USE_AFTER_RET    0xf5
  71 #define ASAN_STACK_MAGIC_USE_AFTER_SCOPE  0xf8
  72
  73 #define ASAN_STACK_FRAME_MAGIC          0x41b58ab3
  74 #define ASAN_STACK_RETIRED_MAGIC        0x45e0360e
  75
  76 #define ASAN_USE_AFTER_SCOPE_ATTRIBUTE  "use after scope memory"
  77
  78 /* Various flags for Asan builtins.  */
  79 enum asan_check_flags
  80 {
  81   ASAN_CHECK_STORE = 1 << 0,
  82   ASAN_CHECK_SCALAR_ACCESS = 1 << 1,
  83   ASAN_CHECK_NON_ZERO_LEN = 1 << 2,
  84   ASAN_CHECK_LAST = 1 << 3
  85 };
  86
  87 /* Flags for Asan check builtins.  */
  88 #define IFN_ASAN_MARK_FLAGS DEF(POISON), DEF(UNPOISON)
  89
  90 enum asan_mark_flags
  91 {
  92 #define DEF(X) ASAN_MARK_##X
  93   IFN_ASAN_MARK_FLAGS
  94 #undef DEF
  95 };
  96
  97 /* Return true if STMT is ASAN_MARK with FLAG as first argument.  */
  98 extern bool asan_mark_p (gimple *stmt, enum asan_mark_flags flag);
  99
 100 /* Return the size of padding needed to insert after a protected
 101    decl of SIZE.  */
 102
 103 static inline unsigned int
 104 asan_red_zone_size (unsigned int size)
 105 {
 106   unsigned int c = size & (ASAN_RED_ZONE_SIZE - 1);
 107   return c ? 2 * ASAN_RED_ZONE_SIZE - c : ASAN_RED_ZONE_SIZE;
 108 }
 109
 110 /* Return how much a stack variable occupis on a stack
 111    including a space for red zone.  */
 112
 113 static inline unsigned HOST_WIDE_INT
 114 asan_var_and_redzone_size (unsigned HOST_WIDE_INT size)
 115 {
 116   if (size <= 4)
 117     return 16;
 118   else if (size <= 16)
 119     return 32;
 120   else if (size <= 128)
 121     return size + 32;
 122   else if (size <= 512)
 123     return size + 64;
 124   else if (size <= 4096)
 125     return size + 128;
 126   else
 127     return size + 256;
 128 }
 129
 130 extern bool set_asan_shadow_offset (const char *);
 131
 132 extern bool asan_shadow_offset_set_p ();
 133
 134 extern void set_sanitized_sections (const char *);
 135
 136 extern bool asan_sanitize_stack_p (void);
 137
 138 extern bool asan_sanitize_allocas_p (void);
 139
 140 extern hash_set<tree> *asan_handled_variables;
 141
 142 /* Return TRUE if builtin with given FCODE will be intercepted by
 143    libasan.  */
 144
 145 static inline bool
 146 asan_intercepted_p (enum built_in_function fcode)
 147 {
 148   return fcode == BUILT_IN_INDEX
 149          || fcode == BUILT_IN_MEMCHR
 150          || fcode == BUILT_IN_MEMCMP
 151          || fcode == BUILT_IN_MEMCPY
 152          || fcode == BUILT_IN_MEMMOVE
 153          || fcode == BUILT_IN_MEMSET
 154          || fcode == BUILT_IN_STRCASECMP
 155          || fcode == BUILT_IN_STRCAT
 156          || fcode == BUILT_IN_STRCHR
 157          || fcode == BUILT_IN_STRCMP
 158          || fcode == BUILT_IN_STRCPY
 159          || fcode == BUILT_IN_STRDUP
 160          || fcode == BUILT_IN_STRLEN
 161          || fcode == BUILT_IN_STRNCASECMP
 162          || fcode == BUILT_IN_STRNCAT
 163          || fcode == BUILT_IN_STRNCMP
 164          || fcode == BUILT_IN_STRCSPN
 165          || fcode == BUILT_IN_STRPBRK
 166          || fcode == BUILT_IN_STRSPN
 167          || fcode == BUILT_IN_STRSTR
 168          || fcode == BUILT_IN_STRNCPY;
 169 }
 170
 171 /* Return TRUE if we should instrument for use-after-scope sanity checking.  */
 172
 173 static inline bool
 174 asan_sanitize_use_after_scope (void)
 175 {
 176   return (flag_sanitize_address_use_after_scope && asan_sanitize_stack_p ());
 177 }
 178
 179 /* Return true if DECL should be guarded on the stack.  */
 180
 181 static inline bool
 182 asan_protect_stack_decl (tree decl)
 183 {
 184   return DECL_P (decl)
 185     && (!DECL_ARTIFICIAL (decl)
 186         || (asan_sanitize_use_after_scope () && TREE_ADDRESSABLE (decl)));
 187 }
 188
 189 /* Return true when flag_sanitize & FLAG is non-zero.  If FN is non-null,
 190    remove all flags mentioned in "no_sanitize" of DECL_ATTRIBUTES.  */
 191
 192 static inline bool
 193 sanitize_flags_p (unsigned int flag, const_tree fn = current_function_decl)
 194 {
 195   unsigned int result_flags = flag_sanitize & flag;
 196   if (result_flags == 0)
 197     return false;
 198
 199   if (fn != NULL_TREE)
 200     {
 201       tree value = lookup_attribute ("no_sanitize", DECL_ATTRIBUTES (fn));
 202       if (value)
 203         result_flags &= ~tree_to_uhwi (TREE_VALUE (value));
 204     }
 205
 206   return result_flags;
 207 }
 208
 209 #endif /* TREE_ASAN */