1*4882a593Smuzhiyun // SPDX-License-Identifier: GPL-2.0-or-later
2*4882a593Smuzhiyun /*
3*4882a593Smuzhiyun * Cryptographic API.
4*4882a593Smuzhiyun *
5*4882a593Smuzhiyun * Cipher operations.
6*4882a593Smuzhiyun *
7*4882a593Smuzhiyun * Copyright (c) 2002 James Morris <jmorris@intercode.com.au>
8*4882a593Smuzhiyun * 2002 Adam J. Richter <adam@yggdrasil.com>
9*4882a593Smuzhiyun * 2004 Jean-Luc Cooke <jlcooke@certainkey.com>
10*4882a593Smuzhiyun */
11*4882a593Smuzhiyun
12*4882a593Smuzhiyun #include <crypto/scatterwalk.h>
13*4882a593Smuzhiyun #include <linux/kernel.h>
14*4882a593Smuzhiyun #include <linux/mm.h>
15*4882a593Smuzhiyun #include <linux/module.h>
16*4882a593Smuzhiyun #include <linux/scatterlist.h>
17*4882a593Smuzhiyun
memcpy_dir(void * buf,void * sgdata,size_t nbytes,int out)18*4882a593Smuzhiyun static inline void memcpy_dir(void *buf, void *sgdata, size_t nbytes, int out)
19*4882a593Smuzhiyun {
20*4882a593Smuzhiyun void *src = out ? buf : sgdata;
21*4882a593Smuzhiyun void *dst = out ? sgdata : buf;
22*4882a593Smuzhiyun
23*4882a593Smuzhiyun memcpy(dst, src, nbytes);
24*4882a593Smuzhiyun }
25*4882a593Smuzhiyun
scatterwalk_copychunks(void * buf,struct scatter_walk * walk,size_t nbytes,int out)26*4882a593Smuzhiyun void scatterwalk_copychunks(void *buf, struct scatter_walk *walk,
27*4882a593Smuzhiyun size_t nbytes, int out)
28*4882a593Smuzhiyun {
29*4882a593Smuzhiyun for (;;) {
30*4882a593Smuzhiyun unsigned int len_this_page = scatterwalk_pagelen(walk);
31*4882a593Smuzhiyun u8 *vaddr;
32*4882a593Smuzhiyun
33*4882a593Smuzhiyun if (len_this_page > nbytes)
34*4882a593Smuzhiyun len_this_page = nbytes;
35*4882a593Smuzhiyun
36*4882a593Smuzhiyun if (out != 2) {
37*4882a593Smuzhiyun vaddr = scatterwalk_map(walk);
38*4882a593Smuzhiyun memcpy_dir(buf, vaddr, len_this_page, out);
39*4882a593Smuzhiyun scatterwalk_unmap(vaddr);
40*4882a593Smuzhiyun }
41*4882a593Smuzhiyun
42*4882a593Smuzhiyun scatterwalk_advance(walk, len_this_page);
43*4882a593Smuzhiyun
44*4882a593Smuzhiyun if (nbytes == len_this_page)
45*4882a593Smuzhiyun break;
46*4882a593Smuzhiyun
47*4882a593Smuzhiyun buf += len_this_page;
48*4882a593Smuzhiyun nbytes -= len_this_page;
49*4882a593Smuzhiyun
50*4882a593Smuzhiyun scatterwalk_pagedone(walk, out & 1, 1);
51*4882a593Smuzhiyun }
52*4882a593Smuzhiyun }
53*4882a593Smuzhiyun EXPORT_SYMBOL_GPL(scatterwalk_copychunks);
54*4882a593Smuzhiyun
scatterwalk_map_and_copy(void * buf,struct scatterlist * sg,unsigned int start,unsigned int nbytes,int out)55*4882a593Smuzhiyun void scatterwalk_map_and_copy(void *buf, struct scatterlist *sg,
56*4882a593Smuzhiyun unsigned int start, unsigned int nbytes, int out)
57*4882a593Smuzhiyun {
58*4882a593Smuzhiyun struct scatter_walk walk;
59*4882a593Smuzhiyun struct scatterlist tmp[2];
60*4882a593Smuzhiyun
61*4882a593Smuzhiyun if (!nbytes)
62*4882a593Smuzhiyun return;
63*4882a593Smuzhiyun
64*4882a593Smuzhiyun sg = scatterwalk_ffwd(tmp, sg, start);
65*4882a593Smuzhiyun
66*4882a593Smuzhiyun scatterwalk_start(&walk, sg);
67*4882a593Smuzhiyun scatterwalk_copychunks(buf, &walk, nbytes, out);
68*4882a593Smuzhiyun scatterwalk_done(&walk, out, 0);
69*4882a593Smuzhiyun }
70*4882a593Smuzhiyun EXPORT_SYMBOL_GPL(scatterwalk_map_and_copy);
71*4882a593Smuzhiyun
scatterwalk_ffwd(struct scatterlist dst[2],struct scatterlist * src,unsigned int len)72*4882a593Smuzhiyun struct scatterlist *scatterwalk_ffwd(struct scatterlist dst[2],
73*4882a593Smuzhiyun struct scatterlist *src,
74*4882a593Smuzhiyun unsigned int len)
75*4882a593Smuzhiyun {
76*4882a593Smuzhiyun for (;;) {
77*4882a593Smuzhiyun if (!len)
78*4882a593Smuzhiyun return src;
79*4882a593Smuzhiyun
80*4882a593Smuzhiyun if (src->length > len)
81*4882a593Smuzhiyun break;
82*4882a593Smuzhiyun
83*4882a593Smuzhiyun len -= src->length;
84*4882a593Smuzhiyun src = sg_next(src);
85*4882a593Smuzhiyun }
86*4882a593Smuzhiyun
87*4882a593Smuzhiyun sg_init_table(dst, 2);
88*4882a593Smuzhiyun sg_set_page(dst, sg_page(src), src->length - len, src->offset + len);
89*4882a593Smuzhiyun scatterwalk_crypto_chain(dst, sg_next(src), 2);
90*4882a593Smuzhiyun
91*4882a593Smuzhiyun return dst;
92*4882a593Smuzhiyun }
93*4882a593Smuzhiyun EXPORT_SYMBOL_GPL(scatterwalk_ffwd);
94