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); 103