sysdeps/unix/bsd/bsd4.4/kfreebsd/readonly-area.c

   1 /* Copyright (C) 2004, 2005, 2009 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3
   4    The GNU C Library is free software; you can redistribute it and/or
   5    modify it under the terms of the GNU Lesser General Public
   6    License as published by the Free Software Foundation; either
   7    version 2.1 of the License, or (at your option) any later version.
   8
   9    The GNU C Library is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12    Lesser General Public License for more details.
  13
  14    You should have received a copy of the GNU Lesser General Public
  15    License along with the GNU C Library; if not, write to the Free
  16    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  17    02111-1307 USA.  */
  18
  19 #include <errno.h>
  20 #include <stdint.h>
  21 #include <stdio.h>
  22 #include <stdio_ext.h>
  23 #include <stdlib.h>
  24 #include <string.h>
  25 #include <unistd.h>
  26 #include <sys/sysctl.h>
  27 #include <sys/user.h>
  28 #include "libio/libioP.h"
  29
  30 /* Return 1 if the whole area PTR .. PTR+SIZE is not writable.
  31    Return -1 if it is writable.  */
  32
  33 int
  34 __readonly_area (const char *ptr, size_t size)
  35 {
  36   const void *ptr_end = ptr + size;
  37
  38   int mib[4];
  39   size_t kve_len = 0;
  40   char *kve_buf, *kve_bufp;
  41
  42   mib[0] = CTL_KERN;
  43   mib[1] = KERN_PROC;
  44   mib[2] = KERN_PROC_VMMAP;
  45   mib[3] = __getpid ();
  46
  47   if (__sysctl (mib, 4, NULL, &kve_len, NULL, 0) != 0)
  48     {
  49       __set_errno (ENOSYS);
  50       return 1;
  51     }
  52
  53   kve_buf = alloca (kve_len);
  54   if (__sysctl (mib, 4, kve_buf, &kve_len, NULL, 0) != 0)
  55     {
  56       __set_errno (ENOSYS);
  57       return 1;
  58     }
  59
  60   kve_bufp = kve_buf;
  61   while (kve_bufp < kve_buf + kve_len)
  62     {
  63       struct kinfo_vmentry *kve = (struct kinfo_vmentry *) (uintptr_t) kve_bufp;
  64       kve_bufp += kve->kve_structsize;
  65
  66       uintptr_t from = kve->kve_start;
  67       uintptr_t to = kve->kve_end;
  68
  69       if (from < (uintptr_t) ptr_end && to > (uintptr_t) ptr)
  70         {
  71           /* Found an entry that at least partially covers the area.  */
  72           if (!(kve->kve_protection & KVME_PROT_READ)
  73               || (kve->kve_protection & KVME_PROT_WRITE))
  74             break;
  75
  76           if (from <= (uintptr_t) ptr && to >= (uintptr_t) ptr_end)
  77             {
  78               size = 0;
  79               break;
  80             }
  81           else if (from <= (uintptr_t) ptr)
  82             size -= to - (uintptr_t) ptr;
  83           else if (to >= (uintptr_t) ptr_end)
  84             size -= (uintptr_t) ptr_end - from;
  85           else
  86             size -= to - from;
  87
  88           if (!size)
  89             break;
  90         }
  91     }
  92
  93   /* If the whole area between ptr and ptr_end is covered by read-only
  94      VMAs, return 1.  Otherwise return -1.  */
  95   return size == 0 ? 1 : -1;
  96 }