1/*
2 * Cryptographic API.
3 *
4 * s390 implementation of the GHASH algorithm for GCM (Galois/Counter Mode).
5 *
6 * Copyright IBM Corp. 2011
7 * Author(s): Gerald Schaefer <gerald.schaefer@de.ibm.com>
8 */
9
10#include <crypto/internal/hash.h>
11#include <linux/module.h>
12
13#include "crypt_s390.h"
14
15#define GHASH_BLOCK_SIZE	16
16#define GHASH_DIGEST_SIZE	16
17
18struct ghash_ctx {
19	u8 key[GHASH_BLOCK_SIZE];
20};
21
22struct ghash_desc_ctx {
23	u8 icv[GHASH_BLOCK_SIZE];
24	u8 key[GHASH_BLOCK_SIZE];
25	u8 buffer[GHASH_BLOCK_SIZE];
26	u32 bytes;
27};
28
29static int ghash_init(struct shash_desc *desc)
30{
31	struct ghash_desc_ctx *dctx = shash_desc_ctx(desc);
32	struct ghash_ctx *ctx = crypto_shash_ctx(desc->tfm);
33
34	memset(dctx, 0, sizeof(*dctx));
35	memcpy(dctx->key, ctx->key, GHASH_BLOCK_SIZE);
36
37	return 0;
38}
39
40static int ghash_setkey(struct crypto_shash *tfm,
41			const u8 *key, unsigned int keylen)
42{
43	struct ghash_ctx *ctx = crypto_shash_ctx(tfm);
44
45	if (keylen != GHASH_BLOCK_SIZE) {
46		crypto_shash_set_flags(tfm, CRYPTO_TFM_RES_BAD_KEY_LEN);
47		return -EINVAL;
48	}
49
50	memcpy(ctx->key, key, GHASH_BLOCK_SIZE);
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	unsigned int n;
60	u8 *buf = dctx->buffer;
61	int ret;
62
63	if (dctx->bytes) {
64		u8 *pos = buf + (GHASH_BLOCK_SIZE - dctx->bytes);
65
66		n = min(srclen, dctx->bytes);
67		dctx->bytes -= n;
68		srclen -= n;
69
70		memcpy(pos, src, n);
71		src += n;
72
73		if (!dctx->bytes) {
74			ret = crypt_s390_kimd(KIMD_GHASH, dctx, buf,
75					      GHASH_BLOCK_SIZE);
76			if (ret != GHASH_BLOCK_SIZE)
77				return -EIO;
78		}
79	}
80
81	n = srclen & ~(GHASH_BLOCK_SIZE - 1);
82	if (n) {
83		ret = crypt_s390_kimd(KIMD_GHASH, dctx, src, n);
84		if (ret != n)
85			return -EIO;
86		src += n;
87		srclen -= n;
88	}
89
90	if (srclen) {
91		dctx->bytes = GHASH_BLOCK_SIZE - srclen;
92		memcpy(buf, src, srclen);
93	}
94
95	return 0;
96}
97
98static int ghash_flush(struct ghash_desc_ctx *dctx)
99{
100	u8 *buf = dctx->buffer;
101	int ret;
102
103	if (dctx->bytes) {
104		u8 *pos = buf + (GHASH_BLOCK_SIZE - dctx->bytes);
105
106		memset(pos, 0, dctx->bytes);
107
108		ret = crypt_s390_kimd(KIMD_GHASH, dctx, buf, GHASH_BLOCK_SIZE);
109		if (ret != GHASH_BLOCK_SIZE)
110			return -EIO;
111
112		dctx->bytes = 0;
113	}
114
115	return 0;
116}
117
118static int ghash_final(struct shash_desc *desc, u8 *dst)
119{
120	struct ghash_desc_ctx *dctx = shash_desc_ctx(desc);
121	int ret;
122
123	ret = ghash_flush(dctx);
124	if (!ret)
125		memcpy(dst, dctx->icv, GHASH_BLOCK_SIZE);
126	return ret;
127}
128
129static struct shash_alg ghash_alg = {
130	.digestsize	= GHASH_DIGEST_SIZE,
131	.init		= ghash_init,
132	.update		= ghash_update,
133	.final		= ghash_final,
134	.setkey		= ghash_setkey,
135	.descsize	= sizeof(struct ghash_desc_ctx),
136	.base		= {
137		.cra_name		= "ghash",
138		.cra_driver_name	= "ghash-s390",
139		.cra_priority		= CRYPT_S390_PRIORITY,
140		.cra_flags		= CRYPTO_ALG_TYPE_SHASH,
141		.cra_blocksize		= GHASH_BLOCK_SIZE,
142		.cra_ctxsize		= sizeof(struct ghash_ctx),
143		.cra_module		= THIS_MODULE,
144	},
145};
146
147static int __init ghash_mod_init(void)
148{
149	if (!crypt_s390_func_available(KIMD_GHASH,
150				       CRYPT_S390_MSA | CRYPT_S390_MSA4))
151		return -EOPNOTSUPP;
152
153	return crypto_register_shash(&ghash_alg);
154}
155
156static void __exit ghash_mod_exit(void)
157{
158	crypto_unregister_shash(&ghash_alg);
159}
160
161module_init(ghash_mod_init);
162module_exit(ghash_mod_exit);
163
164MODULE_ALIAS_CRYPTO("ghash");
165
166MODULE_LICENSE("GPL");
167MODULE_DESCRIPTION("GHASH Message Digest Algorithm, s390 implementation");
168