summaryrefslogtreecommitdiffstats
path: root/crypto/hmac.c
blob: 02aa53ea14aae037f66cdf55c25196cce0d12a5c (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
/*
 * Cryptographic API.
 *
 * HMAC: Keyed-Hashing for Message Authentication (RFC2104).
 *
 * Copyright (c) 2002 James Morris <jmorris@intercode.com.au>
 * Copyright (c) 2006 Herbert Xu <herbert@gondor.apana.org.au>
 *
 * The HMAC implementation is derived from USAGI.
 * Copyright (c) 2002 Kazunori Miyazawa <miyazawa@linux-ipv6.org> / USAGI
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the Free
 * Software Foundation; either version 2 of the License, or (at your option)
 * any later version.
 *
 */

#include <crypto/internal/hash.h>
#include <crypto/scatterwalk.h>
#include <linux/err.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/scatterlist.h>
#include <linux/slab.h>
#include <linux/string.h>

struct hmac_ctx {
	struct shash_desc *desc;
};

static inline void *align_ptr(void *p, unsigned int align)
{
	return (void *)ALIGN((unsigned long)p, align);
}

static inline struct hmac_ctx *hmac_ctx(struct crypto_shash *tfm)
{
	return align_ptr(crypto_shash_ctx_aligned(tfm) +
			 crypto_shash_blocksize(tfm) * 2 +
			 crypto_shash_digestsize(tfm),
			 crypto_tfm_ctx_alignment());
}

static int hmac_setkey(struct crypto_shash *parent,
		       const u8 *inkey, unsigned int keylen)
{
	int bs = crypto_shash_blocksize(parent);
	int ds = crypto_shash_digestsize(parent);
	char *ipad = crypto_shash_ctx_aligned(parent);
	char *opad = ipad + bs;
	char *digest = opad + bs;
	struct hmac_ctx *ctx = align_ptr(digest + ds,
					 crypto_tfm_ctx_alignment());
	unsigned int i;

	if (keylen > bs) {
		int err;

		ctx->desc->flags = crypto_shash_get_flags(parent) &
				   CRYPTO_TFM_REQ_MAY_SLEEP;

		err = crypto_shash_digest(ctx->desc, inkey, keylen, digest);
		if (err)
			return err;

		inkey = digest;
		keylen = ds;
	}

	memcpy(ipad, inkey, keylen);
	memset(ipad + keylen, 0, bs - keylen);
	memcpy(opad, ipad, bs);

	for (i = 0; i < bs; i++) {
		ipad[i] ^= 0x36;
		opad[i] ^= 0x5c;
	}

	return 0;
}

static int hmac_init(struct shash_desc *pdesc)
{
	struct crypto_shash *parent = pdesc->tfm;
	int bs = crypto_shash_blocksize(parent);
	int ds = crypto_shash_digestsize(parent);
	char *ipad = crypto_shash_ctx_aligned(parent);
	struct hmac_ctx *ctx = align_ptr(ipad + bs * 2 + ds,
					 crypto_tfm_ctx_alignment());
	struct shash_desc *desc = shash_desc_ctx(pdesc);

	desc->tfm = ctx->desc->tfm;
	desc->flags = pdesc->flags & CRYPTO_TFM_REQ_MAY_SLEEP;

	return crypto_shash_init(desc) ?:
	       crypto_shash_update(desc, ipad, bs);
}

static int hmac_update(struct shash_desc *pdesc,
		       const u8 *data, unsigned int nbytes)
{
	struct shash_desc *desc = shash_desc_ctx(pdesc);

	desc->flags = pdesc->flags & CRYPTO_TFM_REQ_MAY_SLEEP;

	return crypto_shash_update(desc, data, nbytes);
}

static int hmac_final(struct shash_desc *pdesc, u8 *out)
{
	struct crypto_shash *parent = pdesc->tfm;
	int bs = crypto_shash_blocksize(parent);
	int ds = crypto_shash_digestsize(parent);
	char *opad = crypto_shash_ctx_aligned(parent) + bs;
	char *digest = opad + bs;
	struct shash_desc *desc = shash_desc_ctx(pdesc);

	desc->flags = pdesc->flags & CRYPTO_TFM_REQ_MAY_SLEEP;

	return crypto_shash_final(desc, digest) ?:
	       crypto_shash_digest(desc, opad, bs + ds, out);
}

static int hmac_finup(struct shash_desc *pdesc, const u8 *data,
		      unsigned int nbytes, u8 *out)
{

	struct crypto_shash *parent = pdesc->tfm;
	int bs = crypto_shash_blocksize(parent);
	int ds = crypto_shash_digestsize(parent);
	char *opad = crypto_shash_ctx_aligned(parent) + bs;
	char *digest = opad + bs;
	struct shash_desc *desc = shash_desc_ctx(pdesc);

	desc->flags = pdesc->flags & CRYPTO_TFM_REQ_MAY_SLEEP;

	return crypto_shash_finup(desc, data, nbytes, digest) ?:
	       crypto_shash_digest(desc, opad, bs + ds, out);
}

static int hmac_init_tfm(struct crypto_tfm *tfm)
{
	struct crypto_shash *parent = __crypto_shash_cast(tfm);
	struct crypto_shash *hash;
	struct crypto_instance *inst = (void *)tfm->__crt_alg;
	struct crypto_shash_spawn *spawn = crypto_instance_ctx(inst);
	struct hmac_ctx *ctx = hmac_ctx(parent);

	hash = crypto_spawn_shash(spawn);
	if (IS_ERR(hash))
		return PTR_ERR(hash);

	parent->descsize = sizeof(struct shash_desc) +
			   crypto_shash_descsize(hash);

	ctx->desc = kmalloc(parent->descsize, GFP_KERNEL);
	if (!ctx->desc) {
		crypto_free_shash(hash);
		return -ENOMEM;
	}

	ctx->desc->tfm = hash;
	return 0;
}

static void hmac_exit_tfm(struct crypto_tfm *tfm)
{
	struct hmac_ctx *ctx = hmac_ctx(__crypto_shash_cast(tfm));
	crypto_free_shash(ctx->desc->tfm);
	kzfree(ctx->desc);
}

static int hmac_create(struct crypto_template *tmpl, struct rtattr **tb)
{
	struct shash_instance *inst;
	struct crypto_alg *alg;
	struct shash_alg *salg;
	int err;
	int ds;

	err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_SHASH);
	if (err)
		return err;

	salg = shash_attr_alg(tb[1], 0, 0);
	if (IS_ERR(salg))
		return PTR_ERR(salg);

	err = -EINVAL;
	ds = salg->digestsize;
	alg = &salg->base;
	if (ds > alg->cra_blocksize)
		goto out_put_alg;

	inst = shash_alloc_instance("hmac", alg);
	err = PTR_ERR(inst);
	if (IS_ERR(inst))
		goto out_put_alg;

	err = crypto_init_shash_spawn(shash_instance_ctx(inst), salg,
				      shash_crypto_instance(inst));
	if (err)
		goto out_free_inst;

	inst->alg.base.cra_priority = alg->cra_priority;
	inst->alg.base.cra_blocksize = alg->cra_blocksize;
	inst->alg.base.cra_alignmask = alg->cra_alignmask;

	inst->alg.digestsize = ds;

	inst->alg.base.cra_ctxsize = sizeof(struct hmac_ctx) +
				     ALIGN(alg->cra_blocksize * 2 + ds,
					   crypto_tfm_ctx_alignment());

	inst->alg.base.cra_init = hmac_init_tfm;
	inst->alg.base.cra_exit = hmac_exit_tfm;

	inst->alg.init = hmac_init;
	inst->alg.update = hmac_update;
	inst->alg.final = hmac_final;
	inst->alg.finup = hmac_finup;
	inst->alg.setkey = hmac_setkey;

	err = shash_register_instance(tmpl, inst);
	if (err) {
out_free_inst:
		shash_free_instance(shash_crypto_instance(inst));
	}

out_put_alg:
	crypto_mod_put(alg);
	return err;
}

static struct crypto_template hmac_tmpl = {
	.name = "hmac",
	.create = hmac_create,
	.free = shash_free_instance,
	.module = THIS_MODULE,
};

static int __init hmac_module_init(void)
{
	return crypto_register_template(&hmac_tmpl);
}

static void __exit hmac_module_exit(void)
{
	crypto_unregister_template(&hmac_tmpl);
}

module_init(hmac_module_init);
module_exit(hmac_module_exit);

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("HMAC hash algorithm");
OpenPOWER on IntegriCloud