1 /*
2 * Cryptographic API.
3 *
4 * Cipher operations.
5 *
6 * Copyright (c) 2002 James Morris <jmorris@intercode.com.au>
7 * 2002 Adam J. Richter <adam@yggdrasil.com>
8 * 2004 Jean-Luc Cooke <jlcooke@certainkey.com>
9 *
10 * This program is free software; you can redistribute it and/or modify it
11 * under the terms of the GNU General Public License as published by the Free
12 * Software Foundation; either version 2 of the License, or (at your option)
13 * any later version.
14 *
15 */
16
17 #include <crypto/scatterwalk.h>
18 #include <linux/kernel.h>
19 #include <linux/mm.h>
20 #include <linux/module.h>
21 #include <linux/scatterlist.h>
22
memcpy_dir(void * buf,void * sgdata,size_t nbytes,int out)23 static inline void memcpy_dir(void *buf, void *sgdata, size_t nbytes, int out)
24 {
25 void *src = out ? buf : sgdata;
26 void *dst = out ? sgdata : buf;
27
28 memcpy(dst, src, nbytes);
29 }
30
scatterwalk_copychunks(void * buf,struct scatter_walk * walk,size_t nbytes,int out)31 void scatterwalk_copychunks(void *buf, struct scatter_walk *walk,
32 size_t nbytes, int out)
33 {
34 for (;;) {
35 unsigned int len_this_page = scatterwalk_pagelen(walk);
36 u8 *vaddr;
37
38 if (len_this_page > nbytes)
39 len_this_page = nbytes;
40
41 if (out != 2) {
42 vaddr = scatterwalk_map(walk);
43 memcpy_dir(buf, vaddr, len_this_page, out);
44 scatterwalk_unmap(vaddr);
45 }
46
47 scatterwalk_advance(walk, len_this_page);
48
49 if (nbytes == len_this_page)
50 break;
51
52 buf += len_this_page;
53 nbytes -= len_this_page;
54
55 scatterwalk_pagedone(walk, out & 1, 1);
56 }
57 }
58 EXPORT_SYMBOL_GPL(scatterwalk_copychunks);
59
scatterwalk_map_and_copy(void * buf,struct scatterlist * sg,unsigned int start,unsigned int nbytes,int out)60 void scatterwalk_map_and_copy(void *buf, struct scatterlist *sg,
61 unsigned int start, unsigned int nbytes, int out)
62 {
63 struct scatter_walk walk;
64 struct scatterlist tmp[2];
65
66 if (!nbytes)
67 return;
68
69 sg = scatterwalk_ffwd(tmp, sg, start);
70
71 scatterwalk_start(&walk, sg);
72 scatterwalk_copychunks(buf, &walk, nbytes, out);
73 scatterwalk_done(&walk, out, 0);
74 }
75 EXPORT_SYMBOL_GPL(scatterwalk_map_and_copy);
76
scatterwalk_ffwd(struct scatterlist dst[2],struct scatterlist * src,unsigned int len)77 struct scatterlist *scatterwalk_ffwd(struct scatterlist dst[2],
78 struct scatterlist *src,
79 unsigned int len)
80 {
81 for (;;) {
82 if (!len)
83 return src;
84
85 if (src->length > len)
86 break;
87
88 len -= src->length;
89 src = sg_next(src);
90 }
91
92 sg_init_table(dst, 2);
93 sg_set_page(dst, sg_page(src), src->length - len, src->offset + len);
94 scatterwalk_crypto_chain(dst, sg_next(src), 2);
95
96 return dst;
97 }
98 EXPORT_SYMBOL_GPL(scatterwalk_ffwd);
99
