gcc/asan.h

/* AddressSanitizer, a fast memory error detector.
   Copyright (C) 2011-2021 Free Software Foundation, Inc.
   Contributed by Kostya Serebryany <kcc@google.com>

This file is part of GCC.

GCC is free software; you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by the Free
Software Foundation; either version 3, or (at your option) any later
version.

GCC is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or
FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
for more details.

You should have received a copy of the GNU General Public License
along with GCC; see the file COPYING3.  If not see
<http://www.gnu.org/licenses/>.  */

#ifndef TREE_ASAN
#define TREE_ASAN

extern void asan_function_start (void);
extern void asan_finish_file (void);
extern rtx_insn *asan_emit_stack_protection (rtx, rtx, unsigned int,
					     HOST_WIDE_INT *, tree *, int);
extern rtx_insn *asan_emit_allocas_unpoison (rtx, rtx, rtx_insn *);
extern bool asan_protect_global (tree, bool ignore_decl_rtl_set_p = false);
extern void initialize_sanitizer_builtins (void);
extern tree asan_dynamic_init_call (bool);
extern bool asan_expand_check_ifn (gimple_stmt_iterator *, bool);
extern bool asan_expand_mark_ifn (gimple_stmt_iterator *);
extern bool asan_expand_poison_ifn (gimple_stmt_iterator *, bool *,
				    hash_map<tree, tree> &);

extern void hwasan_record_frame_init ();
extern void hwasan_record_stack_var (rtx, rtx, poly_int64, poly_int64);
extern void hwasan_emit_prologue ();
extern rtx_insn *hwasan_emit_untag_frame (rtx, rtx);
extern rtx hwasan_get_frame_extent ();
extern rtx hwasan_frame_base ();
extern void hwasan_maybe_emit_frame_base_init (void);
extern bool stack_vars_base_reg_p (rtx);
extern uint8_t hwasan_current_frame_tag ();
extern void hwasan_increment_frame_tag ();
extern rtx hwasan_truncate_to_tag_size (rtx, rtx);
extern void hwasan_finish_file (void);
extern bool hwasan_sanitize_p (void);
extern bool hwasan_sanitize_stack_p (void);
extern bool hwasan_sanitize_allocas_p (void);
extern bool hwasan_expand_check_ifn (gimple_stmt_iterator *, bool);
extern bool hwasan_expand_mark_ifn (gimple_stmt_iterator *);
extern bool gate_hwasan (void);

extern gimple_stmt_iterator create_cond_insert_point
     (gimple_stmt_iterator *, bool, bool, bool, basic_block *, basic_block *);

/* Alias set for accessing the shadow memory.  */
extern alias_set_type asan_shadow_set;

/* Hash set of labels that are either used in a goto, or their address
   has been taken.  */
extern hash_set <tree> *asan_used_labels;

/* Shadow memory is found at
   (address >> ASAN_SHADOW_SHIFT) + asan_shadow_offset ().  */
#define ASAN_SHADOW_SHIFT	3
#define ASAN_SHADOW_GRANULARITY (1UL << ASAN_SHADOW_SHIFT)

/* Red zone size, stack and global variables are padded by ASAN_RED_ZONE_SIZE
   up to 2 * ASAN_RED_ZONE_SIZE - 1 bytes.  */
#define ASAN_RED_ZONE_SIZE	32

/* Stack variable use more compact red zones.  The size includes also
   size of variable itself.  */

#define ASAN_MIN_RED_ZONE_SIZE	16

/* Shadow memory values for stack protection.  Left is below protected vars,
   the first pointer in stack corresponding to that offset contains
   ASAN_STACK_FRAME_MAGIC word, the second pointer to a string describing
   the frame.  Middle is for padding in between variables, right is
   above the last protected variable and partial immediately after variables
   up to ASAN_RED_ZONE_SIZE alignment.  */
#define ASAN_STACK_MAGIC_LEFT		  0xf1
#define ASAN_STACK_MAGIC_MIDDLE		  0xf2
#define ASAN_STACK_MAGIC_RIGHT		  0xf3
#define ASAN_STACK_MAGIC_USE_AFTER_RET	  0xf5
#define ASAN_STACK_MAGIC_USE_AFTER_SCOPE  0xf8

#define ASAN_STACK_FRAME_MAGIC		0x41b58ab3
#define ASAN_STACK_RETIRED_MAGIC	0x45e0360e

#define ASAN_USE_AFTER_SCOPE_ATTRIBUTE	"use after scope memory"

/* NOTE: The values below and the hooks under targetm.memtag define an ABI and
   are hard-coded to these values in libhwasan, hence they can't be changed
   independently here.  */
/* How many bits are used to store a tag in a pointer.
   The default version uses the entire top byte of a pointer (i.e. 8 bits).  */
#define HWASAN_TAG_SIZE targetm.memtag.tag_size ()
/* Tag Granule of HWASAN shadow stack.
   This is the size in real memory that each byte in the shadow memory refers
   to.  I.e. if a variable is X bytes long in memory then its tag in shadow
   memory will span X / HWASAN_TAG_GRANULE_SIZE bytes.
   Most variables will need to be aligned to this amount since two variables
   that are neighbors in memory and share a tag granule would need to share the
   same tag (the shared tag granule can only store one tag).  */
#define HWASAN_TAG_GRANULE_SIZE targetm.memtag.granule_size ()
/* Define the tag for the stack background.
   This defines what tag the stack pointer will be and hence what tag all
   variables that are not given special tags are (e.g. spilled registers,
   and parameters passed on the stack).  */
#define HWASAN_STACK_BACKGROUND gen_int_mode (0, QImode)

/* Various flags for Asan builtins.  */
enum asan_check_flags
{
  ASAN_CHECK_STORE = 1 << 0,
  ASAN_CHECK_SCALAR_ACCESS = 1 << 1,
  ASAN_CHECK_NON_ZERO_LEN = 1 << 2,
  ASAN_CHECK_LAST = 1 << 3
};

/* Flags for Asan check builtins.  */
#define IFN_ASAN_MARK_FLAGS DEF(POISON), DEF(UNPOISON)

enum asan_mark_flags
{
#define DEF(X) ASAN_MARK_##X
  IFN_ASAN_MARK_FLAGS
#undef DEF
};

/* Return true if STMT is ASAN_MARK with FLAG as first argument.  */
extern bool asan_mark_p (gimple *stmt, enum asan_mark_flags flag);

/* Return the size of padding needed to insert after a protected
   decl of SIZE.  */

static inline unsigned int
asan_red_zone_size (unsigned int size)
{
  unsigned int c = size & (ASAN_RED_ZONE_SIZE - 1);
  return c ? 2 * ASAN_RED_ZONE_SIZE - c : ASAN_RED_ZONE_SIZE;
}

/* Return how much a stack variable occupis on a stack
   including a space for red zone.  */

static inline unsigned HOST_WIDE_INT
asan_var_and_redzone_size (unsigned HOST_WIDE_INT size)
{
  if (size <= 4)
    return 16;
  else if (size <= 16)
    return 32;
  else if (size <= 128)
    return size + 32;
  else if (size <= 512)
    return size + 64;
  else if (size <= 4096)
    return size + 128;
  else
    return size + 256;
}

extern bool set_asan_shadow_offset (const char *);

extern bool asan_shadow_offset_set_p ();

extern void set_sanitized_sections (const char *);

extern bool asan_sanitize_stack_p (void);

extern bool asan_sanitize_allocas_p (void);

extern hash_set<tree> *asan_handled_variables;

/* Return TRUE if builtin with given FCODE will be intercepted by
   libasan.  */

static inline bool
asan_intercepted_p (enum built_in_function fcode)
{
  if (hwasan_sanitize_p ())
    return false;

  return fcode == BUILT_IN_INDEX
	 || fcode == BUILT_IN_MEMCHR
	 || fcode == BUILT_IN_MEMCMP
	 || fcode == BUILT_IN_MEMCPY
	 || fcode == BUILT_IN_MEMMOVE
	 || fcode == BUILT_IN_MEMSET
	 || fcode == BUILT_IN_STRCASECMP
	 || fcode == BUILT_IN_STRCAT
	 || fcode == BUILT_IN_STRCHR
	 || fcode == BUILT_IN_STRCMP
	 || fcode == BUILT_IN_STRCPY
	 || fcode == BUILT_IN_STRDUP
	 || fcode == BUILT_IN_STRLEN
	 || fcode == BUILT_IN_STRNCASECMP
	 || fcode == BUILT_IN_STRNCAT
	 || fcode == BUILT_IN_STRNCMP
	 || fcode == BUILT_IN_STRCSPN
	 || fcode == BUILT_IN_STRPBRK
	 || fcode == BUILT_IN_STRSPN
	 || fcode == BUILT_IN_STRSTR
	 || fcode == BUILT_IN_STRNCPY;
}

/* Return TRUE if we should instrument for use-after-scope sanity checking.  */

static inline bool
asan_sanitize_use_after_scope (void)
{
  return (flag_sanitize_address_use_after_scope
	  && (asan_sanitize_stack_p () || hwasan_sanitize_stack_p ()));
}

/* Return true if DECL should be guarded on the stack.  */

static inline bool
asan_protect_stack_decl (tree decl)
{
  return DECL_P (decl)
    && (!DECL_ARTIFICIAL (decl)
	|| (asan_sanitize_use_after_scope () && TREE_ADDRESSABLE (decl)));
}

/* Return true when flag_sanitize & FLAG is non-zero.  If FN is non-null,
   remove all flags mentioned in "no_sanitize" of DECL_ATTRIBUTES.  */

static inline bool
sanitize_flags_p (unsigned int flag, const_tree fn = current_function_decl)
{
  unsigned int result_flags = flag_sanitize & flag;
  if (result_flags == 0)
    return false;

  if (fn != NULL_TREE)
    {
      tree value = lookup_attribute ("no_sanitize", DECL_ATTRIBUTES (fn));
      if (value)
	result_flags &= ~tree_to_uhwi (TREE_VALUE (value));
    }

  return result_flags;
}

/* Return true when coverage sanitization should happend for FN function.  */

static inline bool
sanitize_coverage_p (const_tree fn = current_function_decl)
{
  return (flag_sanitize_coverage
	  && (fn == NULL_TREE
	      || lookup_attribute ("no_sanitize_coverage",
				   DECL_ATTRIBUTES (fn)) == NULL_TREE));
}

#endif /* TREE_ASAN */