hmac.c 6.83 KB
Newer Older
Linus Torvalds's avatar
Linus Torvalds committed
1 2 3 4 5 6
/*
 * Cryptographic API.
 *
 * HMAC: Keyed-Hashing for Message Authentication (RFC2104).
 *
 * Copyright (c) 2002 James Morris <jmorris@intercode.com.au>
7
 * Copyright (c) 2006 Herbert Xu <herbert@gondor.apana.org.au>
Linus Torvalds's avatar
Linus Torvalds committed
8 9 10 11 12 13
 *
 * 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
14
 * Software Foundation; either version 2 of the License, or (at your option)
Linus Torvalds's avatar
Linus Torvalds committed
15 16 17
 * any later version.
 *
 */
18

19
#include <crypto/hmac.h>
20
#include <crypto/internal/hash.h>
21
#include <crypto/scatterwalk.h>
22 23 24 25
#include <linux/err.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
26
#include <linux/scatterlist.h>
27 28 29
#include <linux/string.h>

struct hmac_ctx {
30
	struct crypto_shash *hash;
31
};
Linus Torvalds's avatar
Linus Torvalds committed
32

33 34 35 36 37
static inline void *align_ptr(void *p, unsigned int align)
{
	return (void *)ALIGN((unsigned long)p, align);
}

38
static inline struct hmac_ctx *hmac_ctx(struct crypto_shash *tfm)
39
{
40
	return align_ptr(crypto_shash_ctx_aligned(tfm) +
41
			 crypto_shash_statesize(tfm) * 2,
42
			 crypto_tfm_ctx_alignment());
43 44
}

45
static int hmac_setkey(struct crypto_shash *parent,
46 47
		       const u8 *inkey, unsigned int keylen)
{
48 49
	int bs = crypto_shash_blocksize(parent);
	int ds = crypto_shash_digestsize(parent);
50
	int ss = crypto_shash_statesize(parent);
51
	char *ipad = crypto_shash_ctx_aligned(parent);
52 53
	char *opad = ipad + ss;
	struct hmac_ctx *ctx = align_ptr(opad + ss,
54
					 crypto_tfm_ctx_alignment());
55
	struct crypto_shash *hash = ctx->hash;
56
	SHASH_DESC_ON_STACK(shash, hash);
57 58
	unsigned int i;

59 60 61
	shash->tfm = hash;
	shash->flags = crypto_shash_get_flags(parent)
		& CRYPTO_TFM_REQ_MAY_SLEEP;
62

63 64 65
	if (keylen > bs) {
		int err;

66
		err = crypto_shash_digest(shash, inkey, keylen, ipad);
67 68 69 70
		if (err)
			return err;

		keylen = ds;
71 72
	} else
		memcpy(ipad, inkey, keylen);
73 74 75 76 77

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

	for (i = 0; i < bs; i++) {
78 79
		ipad[i] ^= HMAC_IPAD_VALUE;
		opad[i] ^= HMAC_OPAD_VALUE;
80 81
	}

82 83 84 85 86 87
	return crypto_shash_init(shash) ?:
	       crypto_shash_update(shash, ipad, bs) ?:
	       crypto_shash_export(shash, ipad) ?:
	       crypto_shash_init(shash) ?:
	       crypto_shash_update(shash, opad, bs) ?:
	       crypto_shash_export(shash, opad);
88 89
}

90 91 92 93 94 95 96 97 98 99
static int hmac_export(struct shash_desc *pdesc, void *out)
{
	struct shash_desc *desc = shash_desc_ctx(pdesc);

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

	return crypto_shash_export(desc, out);
}

static int hmac_import(struct shash_desc *pdesc, const void *in)
100
{
101
	struct shash_desc *desc = shash_desc_ctx(pdesc);
102
	struct hmac_ctx *ctx = hmac_ctx(pdesc->tfm);
103

104
	desc->tfm = ctx->hash;
105 106
	desc->flags = pdesc->flags & CRYPTO_TFM_REQ_MAY_SLEEP;

107 108 109 110 111 112
	return crypto_shash_import(desc, in);
}

static int hmac_init(struct shash_desc *pdesc)
{
	return hmac_import(pdesc, crypto_shash_ctx_aligned(pdesc->tfm));
113 114
}

115 116
static int hmac_update(struct shash_desc *pdesc,
		       const u8 *data, unsigned int nbytes)
117
{
118
	struct shash_desc *desc = shash_desc_ctx(pdesc);
119

120
	desc->flags = pdesc->flags & CRYPTO_TFM_REQ_MAY_SLEEP;
121

122
	return crypto_shash_update(desc, data, nbytes);
123 124
}

125
static int hmac_final(struct shash_desc *pdesc, u8 *out)
126
{
127 128
	struct crypto_shash *parent = pdesc->tfm;
	int ds = crypto_shash_digestsize(parent);
129 130
	int ss = crypto_shash_statesize(parent);
	char *opad = crypto_shash_ctx_aligned(parent) + ss;
131
	struct shash_desc *desc = shash_desc_ctx(pdesc);
132

133
	desc->flags = pdesc->flags & CRYPTO_TFM_REQ_MAY_SLEEP;
134

135 136 137
	return crypto_shash_final(desc, out) ?:
	       crypto_shash_import(desc, opad) ?:
	       crypto_shash_finup(desc, out, ds, out);
138 139
}

140 141
static int hmac_finup(struct shash_desc *pdesc, const u8 *data,
		      unsigned int nbytes, u8 *out)
142 143
{

144 145
	struct crypto_shash *parent = pdesc->tfm;
	int ds = crypto_shash_digestsize(parent);
146 147
	int ss = crypto_shash_statesize(parent);
	char *opad = crypto_shash_ctx_aligned(parent) + ss;
148
	struct shash_desc *desc = shash_desc_ctx(pdesc);
149

150
	desc->flags = pdesc->flags & CRYPTO_TFM_REQ_MAY_SLEEP;
151

152 153 154
	return crypto_shash_finup(desc, data, nbytes, out) ?:
	       crypto_shash_import(desc, opad) ?:
	       crypto_shash_finup(desc, out, ds, out);
155 156 157 158
}

static int hmac_init_tfm(struct crypto_tfm *tfm)
{
159 160
	struct crypto_shash *parent = __crypto_shash_cast(tfm);
	struct crypto_shash *hash;
161
	struct crypto_instance *inst = (void *)tfm->__crt_alg;
162 163
	struct crypto_shash_spawn *spawn = crypto_instance_ctx(inst);
	struct hmac_ctx *ctx = hmac_ctx(parent);
164

165
	hash = crypto_spawn_shash(spawn);
166 167
	if (IS_ERR(hash))
		return PTR_ERR(hash);
168

169 170 171
	parent->descsize = sizeof(struct shash_desc) +
			   crypto_shash_descsize(hash);

172
	ctx->hash = hash;
173 174 175 176 177
	return 0;
}

static void hmac_exit_tfm(struct crypto_tfm *tfm)
{
178
	struct hmac_ctx *ctx = hmac_ctx(__crypto_shash_cast(tfm));
179
	crypto_free_shash(ctx->hash);
180 181
}

182
static int hmac_create(struct crypto_template *tmpl, struct rtattr **tb)
183
{
184
	struct shash_instance *inst;
185
	struct crypto_alg *alg;
186
	struct shash_alg *salg;
187
	int err;
188
	int ds;
189
	int ss;
190

191
	err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_SHASH);
192
	if (err)
193 194 195 196 197 198 199 200
		return err;

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

	err = -EINVAL;
	ds = salg->digestsize;
201
	ss = salg->statesize;
202
	alg = &salg->base;
203 204
	if (ds > alg->cra_blocksize ||
	    ss < alg->cra_blocksize)
205 206
		goto out_put_alg;

207
	inst = shash_alloc_instance("hmac", alg);
208
	err = PTR_ERR(inst);
209 210 211
	if (IS_ERR(inst))
		goto out_put_alg;

212 213 214 215 216 217 218 219
	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;
220

221
	ss = ALIGN(ss, alg->cra_alignmask + 1);
222
	inst->alg.digestsize = ds;
223
	inst->alg.statesize = ss;
224

225
	inst->alg.base.cra_ctxsize = sizeof(struct hmac_ctx) +
226
				     ALIGN(ss * 2, crypto_tfm_ctx_alignment());
227

228 229
	inst->alg.base.cra_init = hmac_init_tfm;
	inst->alg.base.cra_exit = hmac_exit_tfm;
230

231 232 233 234
	inst->alg.init = hmac_init;
	inst->alg.update = hmac_update;
	inst->alg.final = hmac_final;
	inst->alg.finup = hmac_finup;
235 236
	inst->alg.export = hmac_export;
	inst->alg.import = hmac_import;
237 238 239 240 241 242 243
	inst->alg.setkey = hmac_setkey;

	err = shash_register_instance(tmpl, inst);
	if (err) {
out_free_inst:
		shash_free_instance(shash_crypto_instance(inst));
	}
244 245 246

out_put_alg:
	crypto_mod_put(alg);
247
	return err;
248 249 250 251
}

static struct crypto_template hmac_tmpl = {
	.name = "hmac",
252 253
	.create = hmac_create,
	.free = shash_free_instance,
254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271
	.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");
272
MODULE_ALIAS_CRYPTO("hmac");