sysdeps/generic/bp-checks.h

   1 /* Bounded-pointer checking macros for C.
   2    Copyright (C) 2000 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4    Contributed by Greg McGary <greg@mcgary.org>
   5
   6    The GNU C Library is free software; you can redistribute it and/or
   7    modify it under the terms of the GNU Lesser General Public
   8    License as published by the Free Software Foundation; either
   9    version 2.1 of the License, or (at your option) any later version.
  10
  11    The GNU C Library is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14    Lesser General Public License for more details.
  15
  16    You should have received a copy of the GNU Lesser General Public
  17    License along with the GNU C Library; if not, write to the Free
  18    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  19    02111-1307 USA.  */
  20
  21 #ifndef _bp_checks_h_
  22 #define _bp_checks_h_ 1
  23
  24 #if __BOUNDED_POINTERS__
  25
  26 # define BOUNDS_VIOLATED (__builtin_trap (), 0)
  27
  28 /* Verify that pointer's value >= low.  Return pointer value.  */
  29 # define CHECK_BOUNDS_LOW(ARG)                                  \
  30   (((__ptrvalue (ARG) < __ptrlow (ARG)) && BOUNDS_VIOLATED),    \
  31    __ptrvalue (ARG))
  32
  33 /* Verify that pointer's value < high.  Return pointer value.  */
  34 # define CHECK_BOUNDS_HIGH(ARG)                         \
  35   (((__ptrvalue (ARG) > __ptrhigh (ARG)) && BOUNDS_VIOLATED),   \
  36    __ptrvalue (ARG))
  37
  38 # define _CHECK_N(ARG, N, COND)                         \
  39   (((COND)                                              \
  40     && (__ptrvalue (ARG) < __ptrlow (ARG)               \
  41         || __ptrvalue (ARG) + (N) > __ptrhigh (ARG))    \
  42     && BOUNDS_VIOLATED),                                \
  43    __ptrvalue (ARG))
  44
  45 extern void *__unbounded __ubp_memchr (const void *__unbounded, int, unsigned);
  46
  47 # define _CHECK_STRING(ARG, COND)                               \
  48   (((COND)                                                      \
  49     && (__ptrvalue (ARG) < __ptrlow (ARG)                       \
  50         || !__ubp_memchr (__ptrvalue (ARG), '\0',                       \
  51                       (__ptrhigh (ARG) - __ptrvalue (ARG))))    \
  52     && BOUNDS_VIOLATED),                                        \
  53    __ptrvalue (ARG))
  54
  55 /* Check bounds of a pointer seated to an array of N objects.  */
  56 # define CHECK_N(ARG, N) _CHECK_N ((ARG), (N), 1)
  57 /* Same as CHECK_N, but tolerate ARG == NULL.  */
  58 # define CHECK_N_NULL_OK(ARG, N) _CHECK_N ((ARG), (N), __ptrvalue (ARG))
  59
  60 /* Check bounds of a pointer seated to a single object.  */
  61 # define CHECK_1(ARG) CHECK_N ((ARG), 1)
  62 /* Same as CHECK_1, but tolerate ARG == NULL.  */
  63 # define CHECK_1_NULL_OK(ARG) CHECK_N_NULL_OK ((ARG), 1)
  64
  65 /* Check for NUL-terminator within string's bounds.  */
  66 # define CHECK_STRING(ARG) _CHECK_STRING ((ARG), 1)
  67 /* Same as CHECK_STRING, but tolerate ARG == NULL.  */
  68 # define CHECK_STRING_NULL_OK(ARG) _CHECK_STRING ((ARG), __ptrvalue (ARG))
  69
  70 /* Check bounds of signal syscall args with type sigset_t.  */
  71 # define CHECK_SIGSET(SET) CHECK_N ((SET), _NSIG / (8 * sizeof *(SET)))
  72 /* Same as CHECK_SIGSET, but tolerate SET == NULL.  */
  73 # define CHECK_SIGSET_NULL_OK(SET) CHECK_N_NULL_OK ((SET), _NSIG / (8 * sizeof *(SET)))
  74
  75 # if defined (_IOC_SIZESHIFT) && defined (_IOC_SIZEBITS)
  76 /* Extract the size of the ioctl data and check its bounds.  */
  77 #  define CHECK_IOCTL(ARG, CMD)                                         \
  78   CHECK_N ((const char *) (ARG),                                        \
  79            (((CMD) >> _IOC_SIZESHIFT) & ((1 << _IOC_SIZEBITS) - 1)))
  80 # else
  81 /* We don't know the size of the ioctl data, so the best we can do
  82    is check that the first byte is within bounds.  */
  83 #  define CHECK_IOCTL(ARG, CMD) CHECK_1 ((const char *) ARG)
  84 # endif
  85
  86 /* Check bounds of `struct flock *' for the locking fcntl commands.  */
  87 # define CHECK_FCNTL(ARG, CMD)                                  \
  88   (((CMD) == F_GETLK || (CMD) == F_SETLK || (CMD) == F_SETLKW)  \
  89    ? CHECK_1 ((struct flock *) ARG) : (unsigned long) (ARG))
  90
  91 /* Check bounds of an array of mincore residency-status flags that
  92    cover a region of NBYTES.  Such a vector occupies one byte per page
  93    of memory.  */
  94 # define CHECK_N_PAGES(ARG, NBYTES)                             \
  95   ({ int _page_size_ = sysconf (_SC_PAGE_SIZE);                 \
  96      CHECK_N ((const char *) (ARG),                             \
  97               ((NBYTES) + _page_size_ - 1) / _page_size_); })
  98
  99 /* Return a bounded pointer with value PTR that satisfies CHECK_N (PTR, N).  */
 100 # define BOUNDED_N(PTR, N)                              \
 101   ({ __typeof (PTR) __bounded _p_;                      \
 102      __ptrvalue _p_ = __ptrlow _p_ = __ptrvalue (PTR);  \
 103      __ptrhigh _p_ = __ptrvalue _p_ + (N);              \
 104      _p_; })
 105
 106 #else /* !__BOUNDED_POINTERS__ */
 107
 108 /* Do nothing if not compiling with -fbounded-pointers.  */
 109
 110 # define BOUNDS_VIOLATED
 111 # define CHECK_BOUNDS_LOW(ARG) (ARG)
 112 # define CHECK_BOUNDS_HIGH(ARG) (ARG)
 113 # define CHECK_1(ARG) (ARG)
 114 # define CHECK_1_NULL_OK(ARG) (ARG)
 115 # define CHECK_N(ARG, N) (ARG)
 116 # define CHECK_N_NULL_OK(ARG, N) (ARG)
 117 # define CHECK_STRING(ARG) (ARG)
 118 # define CHECK_SIGSET(SET) (SET)
 119 # define CHECK_SIGSET_NULL_OK(SET) (SET)
 120 # define CHECK_IOCTL(ARG, CMD) (ARG)
 121 # define CHECK_FCNTL(ARG, CMD) (ARG)
 122 # define CHECK_N_PAGES(ARG, NBYTES) (ARG)
 123 # define BOUNDED_N(PTR, N) (PTR)
 124
 125 #endif /* !__BOUNDED_POINTERS__ */
 126
 127 #define BOUNDED_1(PTR) BOUNDED_N (PTR, 1)
 128
 129 #endif /* _bp_checks_h_ */