gcc/asan.h

   1 /* AddressSanitizer, a fast memory error detector.
   2    Copyright (C) 2011-2021 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 void hwasan_record_frame_init ();
  38 extern void hwasan_record_stack_var (rtx, rtx, poly_int64, poly_int64);
  39 extern void hwasan_emit_prologue ();
  40 extern rtx_insn *hwasan_emit_untag_frame (rtx, rtx);
  41 extern rtx hwasan_get_frame_extent ();
  42 extern rtx hwasan_frame_base ();
  43 extern void hwasan_maybe_emit_frame_base_init (void);
  44 extern bool stack_vars_base_reg_p (rtx);
  45 extern uint8_t hwasan_current_frame_tag ();
  46 extern void hwasan_increment_frame_tag ();
  47 extern rtx hwasan_truncate_to_tag_size (rtx, rtx);
  48 extern void hwasan_finish_file (void);
  49 extern bool hwasan_sanitize_p (void);
  50 extern bool hwasan_sanitize_stack_p (void);
  51 extern bool hwasan_sanitize_allocas_p (void);
  52 extern bool hwasan_expand_check_ifn (gimple_stmt_iterator *, bool);
  53 extern bool hwasan_expand_mark_ifn (gimple_stmt_iterator *);
  54 extern bool gate_hwasan (void);
  55
  56 extern gimple_stmt_iterator create_cond_insert_point
  57      (gimple_stmt_iterator *, bool, bool, bool, basic_block *, basic_block *);
  58
  59 /* Alias set for accessing the shadow memory.  */
  60 extern alias_set_type asan_shadow_set;
  61
  62 /* Hash set of labels that are either used in a goto, or their address
  63    has been taken.  */
  64 extern hash_set <tree> *asan_used_labels;
  65
  66 /* Shadow memory is found at
  67    (address >> ASAN_SHADOW_SHIFT) + asan_shadow_offset ().  */
  68 #define ASAN_SHADOW_SHIFT       3
  69 #define ASAN_SHADOW_GRANULARITY (1UL << ASAN_SHADOW_SHIFT)
  70
  71 /* Red zone size, stack and global variables are padded by ASAN_RED_ZONE_SIZE
  72    up to 2 * ASAN_RED_ZONE_SIZE - 1 bytes.  */
  73 #define ASAN_RED_ZONE_SIZE      32
  74
  75 /* Stack variable use more compact red zones.  The size includes also
  76    size of variable itself.  */
  77
  78 #define ASAN_MIN_RED_ZONE_SIZE  16
  79
  80 /* Shadow memory values for stack protection.  Left is below protected vars,
  81    the first pointer in stack corresponding to that offset contains
  82    ASAN_STACK_FRAME_MAGIC word, the second pointer to a string describing
  83    the frame.  Middle is for padding in between variables, right is
  84    above the last protected variable and partial immediately after variables
  85    up to ASAN_RED_ZONE_SIZE alignment.  */
  86 #define ASAN_STACK_MAGIC_LEFT             0xf1
  87 #define ASAN_STACK_MAGIC_MIDDLE           0xf2
  88 #define ASAN_STACK_MAGIC_RIGHT            0xf3
  89 #define ASAN_STACK_MAGIC_USE_AFTER_RET    0xf5
  90 #define ASAN_STACK_MAGIC_USE_AFTER_SCOPE  0xf8
  91
  92 #define ASAN_STACK_FRAME_MAGIC          0x41b58ab3
  93 #define ASAN_STACK_RETIRED_MAGIC        0x45e0360e
  94
  95 #define ASAN_USE_AFTER_SCOPE_ATTRIBUTE  "use after scope memory"
  96
  97 /* NOTE: The values below and the hooks under targetm.memtag define an ABI and
  98    are hard-coded to these values in libhwasan, hence they can't be changed
  99    independently here.  */
 100 /* How many bits are used to store a tag in a pointer.
 101    The default version uses the entire top byte of a pointer (i.e. 8 bits).  */
 102 #define HWASAN_TAG_SIZE targetm.memtag.tag_size ()
 103 /* Tag Granule of HWASAN shadow stack.
 104    This is the size in real memory that each byte in the shadow memory refers
 105    to.  I.e. if a variable is X bytes long in memory then its tag in shadow
 106    memory will span X / HWASAN_TAG_GRANULE_SIZE bytes.
 107    Most variables will need to be aligned to this amount since two variables
 108    that are neighbors in memory and share a tag granule would need to share the
 109    same tag (the shared tag granule can only store one tag).  */
 110 #define HWASAN_TAG_GRANULE_SIZE targetm.memtag.granule_size ()
 111 /* Define the tag for the stack background.
 112    This defines what tag the stack pointer will be and hence what tag all
 113    variables that are not given special tags are (e.g. spilled registers,
 114    and parameters passed on the stack).  */
 115 #define HWASAN_STACK_BACKGROUND gen_int_mode (0, QImode)
 116
 117 /* Various flags for Asan builtins.  */
 118 enum asan_check_flags
 119 {
 120   ASAN_CHECK_STORE = 1 << 0,
 121   ASAN_CHECK_SCALAR_ACCESS = 1 << 1,
 122   ASAN_CHECK_NON_ZERO_LEN = 1 << 2,
 123   ASAN_CHECK_LAST = 1 << 3
 124 };
 125
 126 /* Flags for Asan check builtins.  */
 127 #define IFN_ASAN_MARK_FLAGS DEF(POISON), DEF(UNPOISON)
 128
 129 enum asan_mark_flags
 130 {
 131 #define DEF(X) ASAN_MARK_##X
 132   IFN_ASAN_MARK_FLAGS
 133 #undef DEF
 134 };
 135
 136 /* Return true if STMT is ASAN_MARK with FLAG as first argument.  */
 137 extern bool asan_mark_p (gimple *stmt, enum asan_mark_flags flag);
 138
 139 /* Return the size of padding needed to insert after a protected
 140    decl of SIZE.  */
 141
 142 static inline unsigned int
 143 asan_red_zone_size (unsigned int size)
 144 {
 145   unsigned int c = size & (ASAN_RED_ZONE_SIZE - 1);
 146   return c ? 2 * ASAN_RED_ZONE_SIZE - c : ASAN_RED_ZONE_SIZE;
 147 }
 148
 149 /* Return how much a stack variable occupis on a stack
 150    including a space for red zone.  */
 151
 152 static inline unsigned HOST_WIDE_INT
 153 asan_var_and_redzone_size (unsigned HOST_WIDE_INT size)
 154 {
 155   if (size <= 4)
 156     return 16;
 157   else if (size <= 16)
 158     return 32;
 159   else if (size <= 128)
 160     return size + 32;
 161   else if (size <= 512)
 162     return size + 64;
 163   else if (size <= 4096)
 164     return size + 128;
 165   else
 166     return size + 256;
 167 }
 168
 169 extern bool set_asan_shadow_offset (const char *);
 170
 171 extern bool asan_shadow_offset_set_p ();
 172
 173 extern void set_sanitized_sections (const char *);
 174
 175 extern bool asan_sanitize_stack_p (void);
 176
 177 extern bool asan_sanitize_allocas_p (void);
 178
 179 extern hash_set<tree> *asan_handled_variables;
 180
 181 /* Return TRUE if builtin with given FCODE will be intercepted by
 182    libasan.  */
 183
 184 static inline bool
 185 asan_intercepted_p (enum built_in_function fcode)
 186 {
 187   if (hwasan_sanitize_p ())
 188     return false;
 189
 190   return fcode == BUILT_IN_INDEX
 191          || fcode == BUILT_IN_MEMCHR
 192          || fcode == BUILT_IN_MEMCMP
 193          || fcode == BUILT_IN_MEMCPY
 194          || fcode == BUILT_IN_MEMMOVE
 195          || fcode == BUILT_IN_MEMSET
 196          || fcode == BUILT_IN_STRCASECMP
 197          || fcode == BUILT_IN_STRCAT
 198          || fcode == BUILT_IN_STRCHR
 199          || fcode == BUILT_IN_STRCMP
 200          || fcode == BUILT_IN_STRCPY
 201          || fcode == BUILT_IN_STRDUP
 202          || fcode == BUILT_IN_STRLEN
 203          || fcode == BUILT_IN_STRNCASECMP
 204          || fcode == BUILT_IN_STRNCAT
 205          || fcode == BUILT_IN_STRNCMP
 206          || fcode == BUILT_IN_STRCSPN
 207          || fcode == BUILT_IN_STRPBRK
 208          || fcode == BUILT_IN_STRSPN
 209          || fcode == BUILT_IN_STRSTR
 210          || fcode == BUILT_IN_STRNCPY;
 211 }
 212
 213 /* Return TRUE if we should instrument for use-after-scope sanity checking.  */
 214
 215 static inline bool
 216 asan_sanitize_use_after_scope (void)
 217 {
 218   return (flag_sanitize_address_use_after_scope
 219           && (asan_sanitize_stack_p () || hwasan_sanitize_stack_p ()));
 220 }
 221
 222 /* Return true if DECL should be guarded on the stack.  */
 223
 224 static inline bool
 225 asan_protect_stack_decl (tree decl)
 226 {
 227   return DECL_P (decl)
 228     && (!DECL_ARTIFICIAL (decl)
 229         || (asan_sanitize_use_after_scope () && TREE_ADDRESSABLE (decl)));
 230 }
 231
 232 /* Return true when flag_sanitize & FLAG is non-zero.  If FN is non-null,
 233    remove all flags mentioned in "no_sanitize" of DECL_ATTRIBUTES.  */
 234
 235 static inline bool
 236 sanitize_flags_p (unsigned int flag, const_tree fn = current_function_decl)
 237 {
 238   unsigned int result_flags = flag_sanitize & flag;
 239   if (result_flags == 0)
 240     return false;
 241
 242   if (fn != NULL_TREE)
 243     {
 244       tree value = lookup_attribute ("no_sanitize", DECL_ATTRIBUTES (fn));
 245       if (value)
 246         result_flags &= ~tree_to_uhwi (TREE_VALUE (value));
 247     }
 248
 249   return result_flags;
 250 }
 251
 252 #endif /* TREE_ASAN */