Root/crypto/ghash-generic.c

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
26struct ghash_ctx {
27    struct gf128mul_4k *gf128;
28};
29
30struct ghash_desc_ctx {
31    u8 buffer[GHASH_BLOCK_SIZE];
32    u32 bytes;
33};
34
35static 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
44static 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
63static 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 (!ctx->gf128)
71        return -ENOKEY;
72
73    if (dctx->bytes) {
74        int n = min(srclen, dctx->bytes);
75        u8 *pos = dst + (GHASH_BLOCK_SIZE - dctx->bytes);
76
77        dctx->bytes -= n;
78        srclen -= n;
79
80        while (n--)
81            *pos++ ^= *src++;
82
83        if (!dctx->bytes)
84            gf128mul_4k_lle((be128 *)dst, ctx->gf128);
85    }
86
87    while (srclen >= GHASH_BLOCK_SIZE) {
88        crypto_xor(dst, src, GHASH_BLOCK_SIZE);
89        gf128mul_4k_lle((be128 *)dst, ctx->gf128);
90        src += GHASH_BLOCK_SIZE;
91        srclen -= GHASH_BLOCK_SIZE;
92    }
93
94    if (srclen) {
95        dctx->bytes = GHASH_BLOCK_SIZE - srclen;
96        while (srclen--)
97            *dst++ ^= *src++;
98    }
99
100    return 0;
101}
102
103static void ghash_flush(struct ghash_ctx *ctx, struct ghash_desc_ctx *dctx)
104{
105    u8 *dst = dctx->buffer;
106
107    if (dctx->bytes) {
108        u8 *tmp = dst + (GHASH_BLOCK_SIZE - dctx->bytes);
109
110        while (dctx->bytes--)
111            *tmp++ ^= 0;
112
113        gf128mul_4k_lle((be128 *)dst, ctx->gf128);
114    }
115
116    dctx->bytes = 0;
117}
118
119static int ghash_final(struct shash_desc *desc, u8 *dst)
120{
121    struct ghash_desc_ctx *dctx = shash_desc_ctx(desc);
122    struct ghash_ctx *ctx = crypto_shash_ctx(desc->tfm);
123    u8 *buf = dctx->buffer;
124
125    if (!ctx->gf128)
126        return -ENOKEY;
127
128    ghash_flush(ctx, dctx);
129    memcpy(dst, buf, GHASH_BLOCK_SIZE);
130
131    return 0;
132}
133
134static void ghash_exit_tfm(struct crypto_tfm *tfm)
135{
136    struct ghash_ctx *ctx = crypto_tfm_ctx(tfm);
137    if (ctx->gf128)
138        gf128mul_free_4k(ctx->gf128);
139}
140
141static struct shash_alg ghash_alg = {
142    .digestsize = GHASH_DIGEST_SIZE,
143    .init = ghash_init,
144    .update = ghash_update,
145    .final = ghash_final,
146    .setkey = ghash_setkey,
147    .descsize = sizeof(struct ghash_desc_ctx),
148    .base = {
149        .cra_name = "ghash",
150        .cra_driver_name = "ghash-generic",
151        .cra_priority = 100,
152        .cra_flags = CRYPTO_ALG_TYPE_SHASH,
153        .cra_blocksize = GHASH_BLOCK_SIZE,
154        .cra_ctxsize = sizeof(struct ghash_ctx),
155        .cra_module = THIS_MODULE,
156        .cra_exit = ghash_exit_tfm,
157    },
158};
159
160static int __init ghash_mod_init(void)
161{
162    return crypto_register_shash(&ghash_alg);
163}
164
165static void __exit ghash_mod_exit(void)
166{
167    crypto_unregister_shash(&ghash_alg);
168}
169
170module_init(ghash_mod_init);
171module_exit(ghash_mod_exit);
172
173MODULE_LICENSE("GPL");
174MODULE_DESCRIPTION("GHASH Message Digest Algorithm");
175MODULE_ALIAS("ghash");
176

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