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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"); |
171 |
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