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
  33         *err_ptr = 0;
  34
  35         if (!len) {
  36                 csum = 0;
  37                 goto out;
  38         }
  39
  40         if (unlikely((len < 0) || !access_ok(VERIFY_READ, src, len))) {
  41                 *err_ptr = -EFAULT;
  42                 csum = (__force unsigned int)sum;
  43                 goto out;
  44         }
  45
  46         csum = csum_partial_copy_generic((void __force *)src, dst,
  47                                          len, sum, err_ptr, NULL);
  48
  49         if (unlikely(*err_ptr)) {
  50                 int missing = __copy_from_user(dst, src, len);
  51
  52                 if (missing) {
  53                         memset(dst + len - missing, 0, missing);
  54                         *err_ptr = -EFAULT;
  55                 } else {
  56                         *err_ptr = 0;
  57                 }
  58
  59                 csum = csum_partial(dst, len, sum);
  60         }
  61
  62 out:
  63         return (__force __wsum)csum;
  64 }
  65 EXPORT_SYMBOL(csum_and_copy_from_user);
  66
  67 __wsum csum_and_copy_to_user(const void *src, void __user *dst, int len,
  68                              __wsum sum, int *err_ptr)
  69 {
  70         unsigned int csum;
  71
  72         might_sleep();
  73
  74         *err_ptr = 0;
  75
  76         if (!len) {
  77                 csum = 0;
  78                 goto out;
  79         }
  80
  81         if (unlikely((len < 0) || !access_ok(VERIFY_WRITE, dst, len))) {
  82                 *err_ptr = -EFAULT;
  83                 csum = -1; /* invalid checksum */
  84                 goto out;
  85         }
  86
  87         csum = csum_partial_copy_generic(src, (void __force *)dst,
  88                                          len, sum, NULL, err_ptr);
  89
  90         if (unlikely(*err_ptr)) {
  91                 csum = csum_partial(src, len, sum);
  92
  93                 if (copy_to_user(dst, src, len)) {
  94                         *err_ptr = -EFAULT;
  95                         csum = -1; /* invalid checksum */
  96                 }
  97         }
  98
  99 out:
 100         return (__force __wsum)csum;
 101 }
 102 EXPORT_SYMBOL(csum_and_copy_to_user);