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