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 #include <linux/kernel.h>
17 #include <linux/mm.h>
18 #include <linux/pagemap.h>
19 #include <linux/highmem.h>
20 #include <asm/scatterlist.h>
21 #include "internal.h"
22 #include "scatterwalk.h"
23
scatterwalk_whichbuf(struct scatter_walk * walk,unsigned int nbytes,void * scratch)24 void *scatterwalk_whichbuf(struct scatter_walk *walk, unsigned int nbytes, void *scratch)
25 {
26 if (nbytes <= walk->len_this_page &&
27 (((unsigned long)walk->data) & (PAGE_CACHE_SIZE - 1)) + nbytes <=
28 PAGE_CACHE_SIZE)
29 return walk->data;
30 else
31 return scratch;
32 }
33
memcpy_dir(void * buf,void * sgdata,size_t nbytes,int out)34 static void memcpy_dir(void *buf, void *sgdata, size_t nbytes, int out)
35 {
36 if (out)
37 memcpy(sgdata, buf, nbytes);
38 else
39 memcpy(buf, sgdata, nbytes);
40 }
41
scatterwalk_start(struct scatter_walk * walk,struct scatterlist * sg)42 void scatterwalk_start(struct scatter_walk *walk, struct scatterlist *sg)
43 {
44 unsigned int rest_of_page;
45
46 walk->sg = sg;
47
48 walk->page = sg->page;
49 walk->len_this_segment = sg->length;
50
51 rest_of_page = PAGE_CACHE_SIZE - (sg->offset & (PAGE_CACHE_SIZE - 1));
52 walk->len_this_page = min(sg->length, rest_of_page);
53 walk->offset = sg->offset;
54 }
55
scatterwalk_map(struct scatter_walk * walk)56 void scatterwalk_map(struct scatter_walk *walk)
57 {
58 walk->data = kmap_atomic(walk->page) + walk->offset;
59 }
60
scatterwalk_pagedone(struct scatter_walk * walk,int out,unsigned int more)61 static void scatterwalk_pagedone(struct scatter_walk *walk, int out,
62 unsigned int more)
63 {
64 /* walk->data may be pointing the first byte of the next page;
65 however, we know we transferred at least one byte. So,
66 walk->data - 1 will be a virtual address in the mapped page. */
67
68 if (out)
69 flush_dcache_page(walk->page);
70
71 if (more) {
72 walk->len_this_segment -= walk->len_this_page;
73
74 if (walk->len_this_segment) {
75 walk->page++;
76 walk->len_this_page = min(walk->len_this_segment,
77 (unsigned)PAGE_CACHE_SIZE);
78 walk->offset = 0;
79 }
80 else
81 scatterwalk_start(walk, sg_next(walk->sg));
82 }
83 }
84
scatterwalk_done(struct scatter_walk * walk,int out,int more)85 void scatterwalk_done(struct scatter_walk *walk, int out, int more)
86 {
87 crypto_kunmap(walk->data, out);
88 if (walk->len_this_page == 0 || !more)
89 scatterwalk_pagedone(walk, out, more);
90 }
91
92 /*
93 * Do not call this unless the total length of all of the fragments
94 * has been verified as multiple of the block size.
95 */
scatterwalk_copychunks(void * buf,struct scatter_walk * walk,size_t nbytes)96 int scatterwalk_copychunks(void *buf, struct scatter_walk *walk,
97 size_t nbytes)
98 {
99 if (buf != walk->data) {
100 while (nbytes > walk->len_this_page) {
101 memcpy_dir(buf, walk->data, walk->len_this_page, out);
102 buf += walk->len_this_page;
103 nbytes -= walk->len_this_page;
104
105 kunmap_atomic(walk->data);
106 scatterwalk_pagedone(walk, out, 1);
107 scatterwalk_map(walk);
108 }
109
110 memcpy_dir(buf, walk->data, nbytes, out);
111 }
112
113 walk->offset += nbytes;
114 walk->len_this_page -= nbytes;
115 walk->len_this_segment -= nbytes;
116 return 0;
117 }
118