arch/powerpc/lib/checksum_wrappers.c

   1 /*
   2  * This program is free software; you can redistribute it and/or modify
   3  * it under the terms of the GNU General Public License as published by
   4  * the Free Software Foundation; either version 2 of the License, or
   5  * (at your option) any later version.
   6  *
   7  * This program is distributed in the hope that it will be useful,
   8  * but WITHOUT ANY WARRANTY; without even the implied warranty of
   9  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  10  * GNU General Public License for more details.
  11  *
  12  * You should have received a copy of the GNU General Public License
  13  * along with this program; if not, write to the Free Software
  14  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  15  *
  16  * Copyright (C) IBM Corporation, 2010
  17  *
  18  * Author: Anton Blanchard <anton@au.ibm.com>
  19  */
  20 #include <linux/export.h>
  21 #include <linux/compiler.h>
  22 #include <linux/types.h>
  23 #include <asm/checksum.h>
  24 #include <linux/uaccess.h>
  25
  26 __wsum csum_and_copy_from_user(const void __user *src, void *dst,
  27                                int len, __wsum sum, int *err_ptr)
  28 {
  29         unsigned int csum;
  30
  31         might_sleep();
  32         allow_read_from_user(src, len);
  33
  34         *err_ptr = 0;
  35
  36         if (!len) {
  37                 csum = 0;
  38                 goto out;
  39         }
  40
  41         if (unlikely((len < 0) || !access_ok(src, len))) {
  42                 *err_ptr = -EFAULT;
  43                 csum = (__force unsigned int)sum;
  44                 goto out;
  45         }
  46
  47         csum = csum_partial_copy_generic((void __force *)src, dst,
  48                                          len, sum, err_ptr, NULL);
  49
  50         if (unlikely(*err_ptr)) {
  51                 int missing = __copy_from_user(dst, src, len);
  52
  53                 if (missing) {
  54                         memset(dst + len - missing, 0, missing);
  55                         *err_ptr = -EFAULT;
  56                 } else {
  57                         *err_ptr = 0;
  58                 }
  59
  60                 csum = csum_partial(dst, len, sum);
  61         }
  62
  63 out:
  64         prevent_read_from_user(src, len);
  65         return (__force __wsum)csum;
  66 }
  67 EXPORT_SYMBOL(csum_and_copy_from_user);
  68
  69 __wsum csum_and_copy_to_user(const void *src, void __user *dst, int len,
  70                              __wsum sum, int *err_ptr)
  71 {
  72         unsigned int csum;
  73
  74         might_sleep();
  75         allow_write_to_user(dst, len);
  76
  77         *err_ptr = 0;
  78
  79         if (!len) {
  80                 csum = 0;
  81                 goto out;
  82         }
  83
  84         if (unlikely((len < 0) || !access_ok(dst, len))) {
  85                 *err_ptr = -EFAULT;
  86                 csum = -1; /* invalid checksum */
  87                 goto out;
  88         }
  89
  90         csum = csum_partial_copy_generic(src, (void __force *)dst,
  91                                          len, sum, NULL, err_ptr);
  92
  93         if (unlikely(*err_ptr)) {
  94                 csum = csum_partial(src, len, sum);
  95
  96                 if (copy_to_user(dst, src, len)) {
  97                         *err_ptr = -EFAULT;
  98                         csum = -1; /* invalid checksum */
  99                 }
 100         }
 101
 102 out:
 103         prevent_write_to_user(dst, len);
 104         return (__force __wsum)csum;
 105 }
 106 EXPORT_SYMBOL(csum_and_copy_to_user);