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
ghash_init(struct shash_desc * desc)24 static 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
ghash_setkey(struct crypto_shash * tfm,const u8 * key,unsigned int keylen)33 static 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 be128 k;
38
39 if (keylen != GHASH_BLOCK_SIZE) {
40 crypto_shash_set_flags(tfm, CRYPTO_TFM_RES_BAD_KEY_LEN);
41 return -EINVAL;
42 }
43
44 if (ctx->gf128)
45 gf128mul_free_4k(ctx->gf128);
46
47 BUILD_BUG_ON(sizeof(k) != GHASH_BLOCK_SIZE);
48 memcpy(&k, key, GHASH_BLOCK_SIZE); /* avoid violating alignment rules */
49 ctx->gf128 = gf128mul_init_4k_lle(&k);
50 memzero_explicit(&k, GHASH_BLOCK_SIZE);
51
52 if (!ctx->gf128)
53 return -ENOMEM;
54
55 return 0;
56 }
57
ghash_update(struct shash_desc * desc,const u8 * src,unsigned int srclen)58 static int ghash_update(struct shash_desc *desc,
59 const u8 *src, unsigned int srclen)
60 {
61 struct ghash_desc_ctx *dctx = shash_desc_ctx(desc);
62 struct ghash_ctx *ctx = crypto_shash_ctx(desc->tfm);
63 u8 *dst = dctx->buffer;
64
65 if (dctx->bytes) {
66 int n = min(srclen, dctx->bytes);
67 u8 *pos = dst + (GHASH_BLOCK_SIZE - dctx->bytes);
68
69 dctx->bytes -= n;
70 srclen -= n;
71
72 while (n--)
73 *pos++ ^= *src++;
74
75 if (!dctx->bytes)
76 gf128mul_4k_lle((be128 *)dst, ctx->gf128);
77 }
78
79 while (srclen >= GHASH_BLOCK_SIZE) {
80 crypto_xor(dst, src, GHASH_BLOCK_SIZE);
81 gf128mul_4k_lle((be128 *)dst, ctx->gf128);
82 src += GHASH_BLOCK_SIZE;
83 srclen -= GHASH_BLOCK_SIZE;
84 }
85
86 if (srclen) {
87 dctx->bytes = GHASH_BLOCK_SIZE - srclen;
88 while (srclen--)
89 *dst++ ^= *src++;
90 }
91
92 return 0;
93 }
94
ghash_flush(struct ghash_ctx * ctx,struct ghash_desc_ctx * dctx)95 static void ghash_flush(struct ghash_ctx *ctx, struct ghash_desc_ctx *dctx)
96 {
97 u8 *dst = dctx->buffer;
98
99 if (dctx->bytes) {
100 u8 *tmp = dst + (GHASH_BLOCK_SIZE - dctx->bytes);
101
102 while (dctx->bytes--)
103 *tmp++ ^= 0;
104
105 gf128mul_4k_lle((be128 *)dst, ctx->gf128);
106 }
107
108 dctx->bytes = 0;
109 }
110
ghash_final(struct shash_desc * desc,u8 * dst)111 static int ghash_final(struct shash_desc *desc, u8 *dst)
112 {
113 struct ghash_desc_ctx *dctx = shash_desc_ctx(desc);
114 struct ghash_ctx *ctx = crypto_shash_ctx(desc->tfm);
115 u8 *buf = dctx->buffer;
116
117 ghash_flush(ctx, dctx);
118 memcpy(dst, buf, GHASH_BLOCK_SIZE);
119
120 return 0;
121 }
122
ghash_exit_tfm(struct crypto_tfm * tfm)123 static void ghash_exit_tfm(struct crypto_tfm *tfm)
124 {
125 struct ghash_ctx *ctx = crypto_tfm_ctx(tfm);
126 if (ctx->gf128)
127 gf128mul_free_4k(ctx->gf128);
128 }
129
130 static struct shash_alg ghash_alg = {
131 .digestsize = GHASH_DIGEST_SIZE,
132 .init = ghash_init,
133 .update = ghash_update,
134 .final = ghash_final,
135 .setkey = ghash_setkey,
136 .descsize = sizeof(struct ghash_desc_ctx),
137 .base = {
138 .cra_name = "ghash",
139 .cra_driver_name = "ghash-generic",
140 .cra_priority = 100,
141 .cra_blocksize = GHASH_BLOCK_SIZE,
142 .cra_ctxsize = sizeof(struct ghash_ctx),
143 .cra_module = THIS_MODULE,
144 .cra_exit = ghash_exit_tfm,
145 },
146 };
147
ghash_mod_init(void)148 static int __init ghash_mod_init(void)
149 {
150 return crypto_register_shash(&ghash_alg);
151 }
152
ghash_mod_exit(void)153 static void __exit ghash_mod_exit(void)
154 {
155 crypto_unregister_shash(&ghash_alg);
156 }
157
158 module_init(ghash_mod_init);
159 module_exit(ghash_mod_exit);
160
161 MODULE_LICENSE("GPL");
162 MODULE_DESCRIPTION("GHASH Message Digest Algorithm");
163 MODULE_ALIAS_CRYPTO("ghash");
164 MODULE_ALIAS_CRYPTO("ghash-generic");
165