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/ghash.h>
18#include <crypto/internal/hash.h>
19#include <linux/crypto.h>
20#include <linux/init.h>
21#include <linux/kernel.h>
22#include <linux/module.h>
23
24static int ghash_init(struct shash_desc *desc)
25{
26 struct ghash_desc_ctx *dctx = shash_desc_ctx(desc);
27
28 memset(dctx, 0, sizeof(*dctx));
29
30 return 0;
31}
32
33static int ghash_setkey(struct crypto_shash *tfm,
34 const u8 *key, unsigned int keylen)
35{
36 struct ghash_ctx *ctx = crypto_shash_ctx(tfm);
37
38 if (keylen != GHASH_BLOCK_SIZE) {
39 crypto_shash_set_flags(tfm, CRYPTO_TFM_RES_BAD_KEY_LEN);
40 return -EINVAL;
41 }
42
43 if (ctx->gf128)
44 gf128mul_free_4k(ctx->gf128);
45 ctx->gf128 = gf128mul_init_4k_lle((be128 *)key);
46 if (!ctx->gf128)
47 return -ENOMEM;
48
49 return 0;
50}
51
52static int ghash_update(struct shash_desc *desc,
53 const u8 *src, unsigned int srclen)
54{
55 struct ghash_desc_ctx *dctx = shash_desc_ctx(desc);
56 struct ghash_ctx *ctx = crypto_shash_ctx(desc->tfm);
57 u8 *dst = dctx->buffer;
58
59 if (dctx->bytes) {
60 int n = min(srclen, dctx->bytes);
61 u8 *pos = dst + (GHASH_BLOCK_SIZE - dctx->bytes);
62
63 dctx->bytes -= n;
64 srclen -= n;
65
66 while (n--)
67 *pos++ ^= *src++;
68
69 if (!dctx->bytes)
70 gf128mul_4k_lle((be128 *)dst, ctx->gf128);
71 }
72
73 while (srclen >= GHASH_BLOCK_SIZE) {
74 crypto_xor(dst, src, GHASH_BLOCK_SIZE);
75 gf128mul_4k_lle((be128 *)dst, ctx->gf128);
76 src += GHASH_BLOCK_SIZE;
77 srclen -= GHASH_BLOCK_SIZE;
78 }
79
80 if (srclen) {
81 dctx->bytes = GHASH_BLOCK_SIZE - srclen;
82 while (srclen--)
83 *dst++ ^= *src++;
84 }
85
86 return 0;
87}
88
89static void ghash_flush(struct ghash_ctx *ctx, struct ghash_desc_ctx *dctx)
90{
91 u8 *dst = dctx->buffer;
92
93 if (dctx->bytes) {
94 u8 *tmp = dst + (GHASH_BLOCK_SIZE - dctx->bytes);
95
96 while (dctx->bytes--)
97 *tmp++ ^= 0;
98
99 gf128mul_4k_lle((be128 *)dst, ctx->gf128);
100 }
101
102 dctx->bytes = 0;
103}
104
105static int ghash_final(struct shash_desc *desc, u8 *dst)
106{
107 struct ghash_desc_ctx *dctx = shash_desc_ctx(desc);
108 struct ghash_ctx *ctx = crypto_shash_ctx(desc->tfm);
109 u8 *buf = dctx->buffer;
110
111 ghash_flush(ctx, dctx);
112 memcpy(dst, buf, GHASH_BLOCK_SIZE);
113
114 return 0;
115}
116
117static void ghash_exit_tfm(struct crypto_tfm *tfm)
118{
119 struct ghash_ctx *ctx = crypto_tfm_ctx(tfm);
120 if (ctx->gf128)
121 gf128mul_free_4k(ctx->gf128);
122}
123
124static struct shash_alg ghash_alg = {
125 .digestsize = GHASH_DIGEST_SIZE,
126 .init = ghash_init,
127 .update = ghash_update,
128 .final = ghash_final,
129 .setkey = ghash_setkey,
130 .descsize = sizeof(struct ghash_desc_ctx),
131 .base = {
132 .cra_name = "ghash",
133 .cra_driver_name = "ghash-generic",
134 .cra_priority = 100,
135 .cra_blocksize = GHASH_BLOCK_SIZE,
136 .cra_ctxsize = sizeof(struct ghash_ctx),
137 .cra_module = THIS_MODULE,
138 .cra_exit = ghash_exit_tfm,
139 },
140};
141
142static int __init ghash_mod_init(void)
143{
144 return crypto_register_shash(&ghash_alg);
145}
146
147static void __exit ghash_mod_exit(void)
148{
149 crypto_unregister_shash(&ghash_alg);
150}
151
152module_init(ghash_mod_init);
153module_exit(ghash_mod_exit);
154
155MODULE_LICENSE("GPL");
156MODULE_DESCRIPTION("GHASH Message Digest Algorithm");
157MODULE_ALIAS_CRYPTO("ghash");
158MODULE_ALIAS_CRYPTO("ghash-generic");
159