[CRYPTO] digest: Add alignment handling
[linux-2.6.git] / crypto / digest.c
1 /*
2  * Cryptographic API.
3  *
4  * Digest operations.
5  *
6  * Copyright (c) 2002 James Morris <jmorris@intercode.com.au>
7  *
8  * This program is free software; you can redistribute it and/or modify it
9  * under the terms of the GNU General Public License as published by the Free
10  * Software Foundation; either version 2 of the License, or (at your option) 
11  * any later version.
12  *
13  */
14 #include <linux/crypto.h>
15 #include <linux/mm.h>
16 #include <linux/errno.h>
17 #include <linux/highmem.h>
18 #include <asm/scatterlist.h>
19 #include "internal.h"
20
21 static void init(struct crypto_tfm *tfm)
22 {
23         tfm->__crt_alg->cra_digest.dia_init(crypto_tfm_ctx(tfm));
24 }
25
26 static void update(struct crypto_tfm *tfm,
27                    struct scatterlist *sg, unsigned int nsg)
28 {
29         unsigned int i;
30         unsigned int alignmask = crypto_tfm_alg_alignmask(tfm);
31
32         for (i = 0; i < nsg; i++) {
33
34                 struct page *pg = sg[i].page;
35                 unsigned int offset = sg[i].offset;
36                 unsigned int l = sg[i].length;
37
38                 do {
39                         unsigned int bytes_from_page = min(l, ((unsigned int)
40                                                            (PAGE_SIZE)) - 
41                                                            offset);
42                         char *src = crypto_kmap(pg, 0);
43                         char *p = src + offset;
44
45                         if (unlikely(offset & alignmask)) {
46                                 unsigned int bytes =
47                                         alignmask + 1 - (offset & alignmask);
48                                 bytes = min(bytes, bytes_from_page);
49                                 tfm->__crt_alg->cra_digest.dia_update
50                                                 (crypto_tfm_ctx(tfm), p,
51                                                  bytes);
52                                 p += bytes;
53                                 bytes_from_page -= bytes;
54                                 l -= bytes;
55                         }
56                         tfm->__crt_alg->cra_digest.dia_update
57                                         (crypto_tfm_ctx(tfm), p,
58                                          bytes_from_page);
59                         crypto_kunmap(src, 0);
60                         crypto_yield(tfm);
61                         offset = 0;
62                         pg++;
63                         l -= bytes_from_page;
64                 } while (l > 0);
65         }
66 }
67
68 static void final(struct crypto_tfm *tfm, u8 *out)
69 {
70         unsigned long alignmask = crypto_tfm_alg_alignmask(tfm);
71         if (unlikely((unsigned long)out & alignmask)) {
72                 unsigned int size = crypto_tfm_alg_digestsize(tfm);
73                 u8 buffer[size + alignmask];
74                 u8 *dst = (u8 *)ALIGN((unsigned long)buffer, alignmask + 1);
75                 tfm->__crt_alg->cra_digest.dia_final(crypto_tfm_ctx(tfm), dst);
76                 memcpy(out, dst, size);
77         } else
78                 tfm->__crt_alg->cra_digest.dia_final(crypto_tfm_ctx(tfm), out);
79 }
80
81 static int setkey(struct crypto_tfm *tfm, const u8 *key, unsigned int keylen)
82 {
83         u32 flags;
84         if (tfm->__crt_alg->cra_digest.dia_setkey == NULL)
85                 return -ENOSYS;
86         return tfm->__crt_alg->cra_digest.dia_setkey(crypto_tfm_ctx(tfm),
87                                                      key, keylen, &flags);
88 }
89
90 static void digest(struct crypto_tfm *tfm,
91                    struct scatterlist *sg, unsigned int nsg, u8 *out)
92 {
93         init(tfm);
94         update(tfm, sg, nsg);
95         final(tfm, out);
96 }
97
98 int crypto_init_digest_flags(struct crypto_tfm *tfm, u32 flags)
99 {
100         return flags ? -EINVAL : 0;
101 }
102
103 int crypto_init_digest_ops(struct crypto_tfm *tfm)
104 {
105         struct digest_tfm *ops = &tfm->crt_digest;
106         
107         ops->dit_init   = init;
108         ops->dit_update = update;
109         ops->dit_final  = final;
110         ops->dit_digest = digest;
111         ops->dit_setkey = setkey;
112         
113         return crypto_alloc_hmac_block(tfm);
114 }
115
116 void crypto_exit_digest_ops(struct crypto_tfm *tfm)
117 {
118         crypto_free_hmac_block(tfm);
119 }