Linux kernel mirror (for testing)
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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * GHASH: digest algorithm for GCM (Galois/Counter Mode).
4 *
5 * Copyright (c) 2007 Nokia Siemens Networks - Mikko Herranen <mh1@iki.fi>
6 * Copyright (c) 2009 Intel Corp.
7 * Author: Huang Ying <ying.huang@intel.com>
8 *
9 * The algorithm implementation is copied from gcm.c.
10 */
11
12#include <crypto/algapi.h>
13#include <crypto/gf128mul.h>
14#include <crypto/ghash.h>
15#include <crypto/internal/hash.h>
16#include <linux/crypto.h>
17#include <linux/init.h>
18#include <linux/kernel.h>
19#include <linux/module.h>
20
21static int ghash_init(struct shash_desc *desc)
22{
23 struct ghash_desc_ctx *dctx = shash_desc_ctx(desc);
24
25 memset(dctx, 0, sizeof(*dctx));
26
27 return 0;
28}
29
30static int ghash_setkey(struct crypto_shash *tfm,
31 const u8 *key, unsigned int keylen)
32{
33 struct ghash_ctx *ctx = crypto_shash_ctx(tfm);
34 be128 k;
35
36 if (keylen != GHASH_BLOCK_SIZE) {
37 crypto_shash_set_flags(tfm, CRYPTO_TFM_RES_BAD_KEY_LEN);
38 return -EINVAL;
39 }
40
41 if (ctx->gf128)
42 gf128mul_free_4k(ctx->gf128);
43
44 BUILD_BUG_ON(sizeof(k) != GHASH_BLOCK_SIZE);
45 memcpy(&k, key, GHASH_BLOCK_SIZE); /* avoid violating alignment rules */
46 ctx->gf128 = gf128mul_init_4k_lle(&k);
47 memzero_explicit(&k, GHASH_BLOCK_SIZE);
48
49 if (!ctx->gf128)
50 return -ENOMEM;
51
52 return 0;
53}
54
55static int ghash_update(struct shash_desc *desc,
56 const u8 *src, unsigned int srclen)
57{
58 struct ghash_desc_ctx *dctx = shash_desc_ctx(desc);
59 struct ghash_ctx *ctx = crypto_shash_ctx(desc->tfm);
60 u8 *dst = dctx->buffer;
61
62 if (dctx->bytes) {
63 int n = min(srclen, dctx->bytes);
64 u8 *pos = dst + (GHASH_BLOCK_SIZE - dctx->bytes);
65
66 dctx->bytes -= n;
67 srclen -= n;
68
69 while (n--)
70 *pos++ ^= *src++;
71
72 if (!dctx->bytes)
73 gf128mul_4k_lle((be128 *)dst, ctx->gf128);
74 }
75
76 while (srclen >= GHASH_BLOCK_SIZE) {
77 crypto_xor(dst, src, GHASH_BLOCK_SIZE);
78 gf128mul_4k_lle((be128 *)dst, ctx->gf128);
79 src += GHASH_BLOCK_SIZE;
80 srclen -= GHASH_BLOCK_SIZE;
81 }
82
83 if (srclen) {
84 dctx->bytes = GHASH_BLOCK_SIZE - srclen;
85 while (srclen--)
86 *dst++ ^= *src++;
87 }
88
89 return 0;
90}
91
92static void ghash_flush(struct ghash_ctx *ctx, struct ghash_desc_ctx *dctx)
93{
94 u8 *dst = dctx->buffer;
95
96 if (dctx->bytes) {
97 u8 *tmp = dst + (GHASH_BLOCK_SIZE - dctx->bytes);
98
99 while (dctx->bytes--)
100 *tmp++ ^= 0;
101
102 gf128mul_4k_lle((be128 *)dst, ctx->gf128);
103 }
104
105 dctx->bytes = 0;
106}
107
108static int ghash_final(struct shash_desc *desc, u8 *dst)
109{
110 struct ghash_desc_ctx *dctx = shash_desc_ctx(desc);
111 struct ghash_ctx *ctx = crypto_shash_ctx(desc->tfm);
112 u8 *buf = dctx->buffer;
113
114 ghash_flush(ctx, dctx);
115 memcpy(dst, buf, GHASH_BLOCK_SIZE);
116
117 return 0;
118}
119
120static void ghash_exit_tfm(struct crypto_tfm *tfm)
121{
122 struct ghash_ctx *ctx = crypto_tfm_ctx(tfm);
123 if (ctx->gf128)
124 gf128mul_free_4k(ctx->gf128);
125}
126
127static struct shash_alg ghash_alg = {
128 .digestsize = GHASH_DIGEST_SIZE,
129 .init = ghash_init,
130 .update = ghash_update,
131 .final = ghash_final,
132 .setkey = ghash_setkey,
133 .descsize = sizeof(struct ghash_desc_ctx),
134 .base = {
135 .cra_name = "ghash",
136 .cra_driver_name = "ghash-generic",
137 .cra_priority = 100,
138 .cra_blocksize = GHASH_BLOCK_SIZE,
139 .cra_ctxsize = sizeof(struct ghash_ctx),
140 .cra_module = THIS_MODULE,
141 .cra_exit = ghash_exit_tfm,
142 },
143};
144
145static int __init ghash_mod_init(void)
146{
147 return crypto_register_shash(&ghash_alg);
148}
149
150static void __exit ghash_mod_exit(void)
151{
152 crypto_unregister_shash(&ghash_alg);
153}
154
155subsys_initcall(ghash_mod_init);
156module_exit(ghash_mod_exit);
157
158MODULE_LICENSE("GPL");
159MODULE_DESCRIPTION("GHASH Message Digest Algorithm");
160MODULE_ALIAS_CRYPTO("ghash");
161MODULE_ALIAS_CRYPTO("ghash-generic");