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); 107