1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Cryptographic API.
4 *
5 * s390 implementation of the GHASH algorithm for GCM (Galois/Counter Mode).
6 *
7 * Copyright IBM Corp. 2011
8 * Author(s): Gerald Schaefer <gerald.schaefer@de.ibm.com>
9 */
10
11 #include <crypto/internal/hash.h>
12 #include <linux/module.h>
13 #include <linux/cpufeature.h>
14 #include <asm/cpacf.h>
15
16 #define GHASH_BLOCK_SIZE 16
17 #define GHASH_DIGEST_SIZE 16
18
19 struct ghash_ctx {
20 u8 key[GHASH_BLOCK_SIZE];
21 };
22
23 struct ghash_desc_ctx {
24 u8 icv[GHASH_BLOCK_SIZE];
25 u8 key[GHASH_BLOCK_SIZE];
26 u8 buffer[GHASH_BLOCK_SIZE];
27 u32 bytes;
28 };
29
ghash_init(struct shash_desc * desc)30 static int ghash_init(struct shash_desc *desc)
31 {
32 struct ghash_desc_ctx *dctx = shash_desc_ctx(desc);
33 struct ghash_ctx *ctx = crypto_shash_ctx(desc->tfm);
34
35 memset(dctx, 0, sizeof(*dctx));
36 memcpy(dctx->key, ctx->key, GHASH_BLOCK_SIZE);
37
38 return 0;
39 }
40
ghash_setkey(struct crypto_shash * tfm,const u8 * key,unsigned int keylen)41 static int ghash_setkey(struct crypto_shash *tfm,
42 const u8 *key, unsigned int keylen)
43 {
44 struct ghash_ctx *ctx = crypto_shash_ctx(tfm);
45
46 if (keylen != GHASH_BLOCK_SIZE) {
47 crypto_shash_set_flags(tfm, CRYPTO_TFM_RES_BAD_KEY_LEN);
48 return -EINVAL;
49 }
50
51 memcpy(ctx->key, key, GHASH_BLOCK_SIZE);
52
53 return 0;
54 }
55
ghash_update(struct shash_desc * desc,const u8 * src,unsigned int srclen)56 static int ghash_update(struct shash_desc *desc,
57 const u8 *src, unsigned int srclen)
58 {
59 struct ghash_desc_ctx *dctx = shash_desc_ctx(desc);
60 unsigned int n;
61 u8 *buf = dctx->buffer;
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 cpacf_kimd(CPACF_KIMD_GHASH, dctx, buf,
75 GHASH_BLOCK_SIZE);
76 }
77 }
78
79 n = srclen & ~(GHASH_BLOCK_SIZE - 1);
80 if (n) {
81 cpacf_kimd(CPACF_KIMD_GHASH, dctx, src, n);
82 src += n;
83 srclen -= n;
84 }
85
86 if (srclen) {
87 dctx->bytes = GHASH_BLOCK_SIZE - srclen;
88 memcpy(buf, src, srclen);
89 }
90
91 return 0;
92 }
93
ghash_flush(struct ghash_desc_ctx * dctx)94 static int ghash_flush(struct ghash_desc_ctx *dctx)
95 {
96 u8 *buf = dctx->buffer;
97
98 if (dctx->bytes) {
99 u8 *pos = buf + (GHASH_BLOCK_SIZE - dctx->bytes);
100
101 memset(pos, 0, dctx->bytes);
102 cpacf_kimd(CPACF_KIMD_GHASH, dctx, buf, GHASH_BLOCK_SIZE);
103 dctx->bytes = 0;
104 }
105
106 return 0;
107 }
108
ghash_final(struct shash_desc * desc,u8 * dst)109 static int ghash_final(struct shash_desc *desc, u8 *dst)
110 {
111 struct ghash_desc_ctx *dctx = shash_desc_ctx(desc);
112 int ret;
113
114 ret = ghash_flush(dctx);
115 if (!ret)
116 memcpy(dst, dctx->icv, GHASH_BLOCK_SIZE);
117 return ret;
118 }
119
120 static struct shash_alg ghash_alg = {
121 .digestsize = GHASH_DIGEST_SIZE,
122 .init = ghash_init,
123 .update = ghash_update,
124 .final = ghash_final,
125 .setkey = ghash_setkey,
126 .descsize = sizeof(struct ghash_desc_ctx),
127 .base = {
128 .cra_name = "ghash",
129 .cra_driver_name = "ghash-s390",
130 .cra_priority = 300,
131 .cra_blocksize = GHASH_BLOCK_SIZE,
132 .cra_ctxsize = sizeof(struct ghash_ctx),
133 .cra_module = THIS_MODULE,
134 },
135 };
136
ghash_mod_init(void)137 static int __init ghash_mod_init(void)
138 {
139 if (!cpacf_query_func(CPACF_KIMD, CPACF_KIMD_GHASH))
140 return -EOPNOTSUPP;
141
142 return crypto_register_shash(&ghash_alg);
143 }
144
ghash_mod_exit(void)145 static void __exit ghash_mod_exit(void)
146 {
147 crypto_unregister_shash(&ghash_alg);
148 }
149
150 module_cpu_feature_match(MSA, ghash_mod_init);
151 module_exit(ghash_mod_exit);
152
153 MODULE_ALIAS_CRYPTO("ghash");
154
155 MODULE_LICENSE("GPL");
156 MODULE_DESCRIPTION("GHASH Message Digest Algorithm, s390 implementation");
157
