Merge branch 'async' of macbook:git/btrfs-unstable
[linux-2.6.git] / crypto / ghash-generic.c
1 /*
2  * GHASH: digest algorithm for GCM (Galois/Counter Mode).
3  *
4  * Copyright (c) 2007 Nokia Siemens Networks - Mikko Herranen <mh1@iki.fi>
5  * Copyright (c) 2009 Intel Corp.
6  *   Author: Huang Ying <ying.huang@intel.com>
7  *
8  * The algorithm implementation is copied from gcm.c.
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 version 2 as published
12  * by the Free Software Foundation.
13  */
14
15 #include <crypto/algapi.h>
16 #include <crypto/gf128mul.h>
17 #include <crypto/internal/hash.h>
18 #include <linux/crypto.h>
19 #include <linux/init.h>
20 #include <linux/kernel.h>
21 #include <linux/module.h>
22
23 #define GHASH_BLOCK_SIZE        16
24 #define GHASH_DIGEST_SIZE       16
25
26 struct ghash_ctx {
27         struct gf128mul_4k *gf128;
28 };
29
30 struct ghash_desc_ctx {
31         u8 buffer[GHASH_BLOCK_SIZE];
32         u32 bytes;
33 };
34
35 static int ghash_init(struct shash_desc *desc)
36 {
37         struct ghash_desc_ctx *dctx = shash_desc_ctx(desc);
38
39         memset(dctx, 0, sizeof(*dctx));
40
41         return 0;
42 }
43
44 static int ghash_setkey(struct crypto_shash *tfm,
45                         const u8 *key, unsigned int keylen)
46 {
47         struct ghash_ctx *ctx = crypto_shash_ctx(tfm);
48
49         if (keylen != GHASH_BLOCK_SIZE) {
50                 crypto_shash_set_flags(tfm, CRYPTO_TFM_RES_BAD_KEY_LEN);
51                 return -EINVAL;
52         }
53
54         if (ctx->gf128)
55                 gf128mul_free_4k(ctx->gf128);
56         ctx->gf128 = gf128mul_init_4k_lle((be128 *)key);
57         if (!ctx->gf128)
58                 return -ENOMEM;
59
60         return 0;
61 }
62
63 static int ghash_update(struct shash_desc *desc,
64                          const u8 *src, unsigned int srclen)
65 {
66         struct ghash_desc_ctx *dctx = shash_desc_ctx(desc);
67         struct ghash_ctx *ctx = crypto_shash_ctx(desc->tfm);
68         u8 *dst = dctx->buffer;
69
70         if (dctx->bytes) {
71                 int n = min(srclen, dctx->bytes);
72                 u8 *pos = dst + (GHASH_BLOCK_SIZE - dctx->bytes);
73
74                 dctx->bytes -= n;
75                 srclen -= n;
76
77                 while (n--)
78                         *pos++ ^= *src++;
79
80                 if (!dctx->bytes)
81                         gf128mul_4k_lle((be128 *)dst, ctx->gf128);
82         }
83
84         while (srclen >= GHASH_BLOCK_SIZE) {
85                 crypto_xor(dst, src, GHASH_BLOCK_SIZE);
86                 gf128mul_4k_lle((be128 *)dst, ctx->gf128);
87                 src += GHASH_BLOCK_SIZE;
88                 srclen -= GHASH_BLOCK_SIZE;
89         }
90
91         if (srclen) {
92                 dctx->bytes = GHASH_BLOCK_SIZE - srclen;
93                 while (srclen--)
94                         *dst++ ^= *src++;
95         }
96
97         return 0;
98 }
99
100 static void ghash_flush(struct ghash_ctx *ctx, struct ghash_desc_ctx *dctx)
101 {
102         u8 *dst = dctx->buffer;
103
104         if (dctx->bytes) {
105                 u8 *tmp = dst + (GHASH_BLOCK_SIZE - dctx->bytes);
106
107                 while (dctx->bytes--)
108                         *tmp++ ^= 0;
109
110                 gf128mul_4k_lle((be128 *)dst, ctx->gf128);
111         }
112
113         dctx->bytes = 0;
114 }
115
116 static int ghash_final(struct shash_desc *desc, u8 *dst)
117 {
118         struct ghash_desc_ctx *dctx = shash_desc_ctx(desc);
119         struct ghash_ctx *ctx = crypto_shash_ctx(desc->tfm);
120         u8 *buf = dctx->buffer;
121
122         ghash_flush(ctx, dctx);
123         memcpy(dst, buf, GHASH_BLOCK_SIZE);
124
125         return 0;
126 }
127
128 static void ghash_exit_tfm(struct crypto_tfm *tfm)
129 {
130         struct ghash_ctx *ctx = crypto_tfm_ctx(tfm);
131         if (ctx->gf128)
132                 gf128mul_free_4k(ctx->gf128);
133 }
134
135 static struct shash_alg ghash_alg = {
136         .digestsize     = GHASH_DIGEST_SIZE,
137         .init           = ghash_init,
138         .update         = ghash_update,
139         .final          = ghash_final,
140         .setkey         = ghash_setkey,
141         .descsize       = sizeof(struct ghash_desc_ctx),
142         .base           = {
143                 .cra_name               = "ghash",
144                 .cra_driver_name        = "ghash-generic",
145                 .cra_priority           = 100,
146                 .cra_flags              = CRYPTO_ALG_TYPE_SHASH,
147                 .cra_blocksize          = GHASH_BLOCK_SIZE,
148                 .cra_ctxsize            = sizeof(struct ghash_ctx),
149                 .cra_module             = THIS_MODULE,
150                 .cra_list               = LIST_HEAD_INIT(ghash_alg.base.cra_list),
151                 .cra_exit               = ghash_exit_tfm,
152         },
153 };
154
155 static int __init ghash_mod_init(void)
156 {
157         return crypto_register_shash(&ghash_alg);
158 }
159
160 static void __exit ghash_mod_exit(void)
161 {
162         crypto_unregister_shash(&ghash_alg);
163 }
164
165 module_init(ghash_mod_init);
166 module_exit(ghash_mod_exit);
167
168 MODULE_LICENSE("GPL");
169 MODULE_DESCRIPTION("GHASH Message Digest Algorithm");
170 MODULE_ALIAS("ghash");