Root/crypto/hmac.c

1/*
2 * Cryptographic API.
3 *
4 * HMAC: Keyed-Hashing for Message Authentication (RFC2104).
5 *
6 * Copyright (c) 2002 James Morris <jmorris@intercode.com.au>
7 * Copyright (c) 2006 Herbert Xu <herbert@gondor.apana.org.au>
8 *
9 * The HMAC implementation is derived from USAGI.
10 * Copyright (c) 2002 Kazunori Miyazawa <miyazawa@linux-ipv6.org> / USAGI
11 *
12 * This program is free software; you can redistribute it and/or modify it
13 * 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)
15 * any later version.
16 *
17 */
18
19#include <crypto/internal/hash.h>
20#include <crypto/scatterwalk.h>
21#include <linux/err.h>
22#include <linux/init.h>
23#include <linux/kernel.h>
24#include <linux/module.h>
25#include <linux/scatterlist.h>
26#include <linux/string.h>
27
28struct hmac_ctx {
29    struct crypto_shash *hash;
30};
31
32static inline void *align_ptr(void *p, unsigned int align)
33{
34    return (void *)ALIGN((unsigned long)p, align);
35}
36
37static inline struct hmac_ctx *hmac_ctx(struct crypto_shash *tfm)
38{
39    return align_ptr(crypto_shash_ctx_aligned(tfm) +
40             crypto_shash_statesize(tfm) * 2,
41             crypto_tfm_ctx_alignment());
42}
43
44static int hmac_setkey(struct crypto_shash *parent,
45               const u8 *inkey, unsigned int keylen)
46{
47    int bs = crypto_shash_blocksize(parent);
48    int ds = crypto_shash_digestsize(parent);
49    int ss = crypto_shash_statesize(parent);
50    char *ipad = crypto_shash_ctx_aligned(parent);
51    char *opad = ipad + ss;
52    struct hmac_ctx *ctx = align_ptr(opad + ss,
53                     crypto_tfm_ctx_alignment());
54    struct crypto_shash *hash = ctx->hash;
55    struct {
56        struct shash_desc shash;
57        char ctx[crypto_shash_descsize(hash)];
58    } desc;
59    unsigned int i;
60
61    desc.shash.tfm = hash;
62    desc.shash.flags = crypto_shash_get_flags(parent) &
63                CRYPTO_TFM_REQ_MAY_SLEEP;
64
65    if (keylen > bs) {
66        int err;
67
68        err = crypto_shash_digest(&desc.shash, inkey, keylen, ipad);
69        if (err)
70            return err;
71
72        keylen = ds;
73    } else
74        memcpy(ipad, inkey, keylen);
75
76    memset(ipad + keylen, 0, bs - keylen);
77    memcpy(opad, ipad, bs);
78
79    for (i = 0; i < bs; i++) {
80        ipad[i] ^= 0x36;
81        opad[i] ^= 0x5c;
82    }
83
84    return crypto_shash_init(&desc.shash) ?:
85           crypto_shash_update(&desc.shash, ipad, bs) ?:
86           crypto_shash_export(&desc.shash, ipad) ?:
87           crypto_shash_init(&desc.shash) ?:
88           crypto_shash_update(&desc.shash, opad, bs) ?:
89           crypto_shash_export(&desc.shash, opad);
90}
91
92static int hmac_export(struct shash_desc *pdesc, void *out)
93{
94    struct shash_desc *desc = shash_desc_ctx(pdesc);
95
96    desc->flags = pdesc->flags & CRYPTO_TFM_REQ_MAY_SLEEP;
97
98    return crypto_shash_export(desc, out);
99}
100
101static int hmac_import(struct shash_desc *pdesc, const void *in)
102{
103    struct shash_desc *desc = shash_desc_ctx(pdesc);
104    struct hmac_ctx *ctx = hmac_ctx(pdesc->tfm);
105
106    desc->tfm = ctx->hash;
107    desc->flags = pdesc->flags & CRYPTO_TFM_REQ_MAY_SLEEP;
108
109    return crypto_shash_import(desc, in);
110}
111
112static int hmac_init(struct shash_desc *pdesc)
113{
114    return hmac_import(pdesc, crypto_shash_ctx_aligned(pdesc->tfm));
115}
116
117static int hmac_update(struct shash_desc *pdesc,
118               const u8 *data, unsigned int nbytes)
119{
120    struct shash_desc *desc = shash_desc_ctx(pdesc);
121
122    desc->flags = pdesc->flags & CRYPTO_TFM_REQ_MAY_SLEEP;
123
124    return crypto_shash_update(desc, data, nbytes);
125}
126
127static int hmac_final(struct shash_desc *pdesc, u8 *out)
128{
129    struct crypto_shash *parent = pdesc->tfm;
130    int ds = crypto_shash_digestsize(parent);
131    int ss = crypto_shash_statesize(parent);
132    char *opad = crypto_shash_ctx_aligned(parent) + ss;
133    struct shash_desc *desc = shash_desc_ctx(pdesc);
134
135    desc->flags = pdesc->flags & CRYPTO_TFM_REQ_MAY_SLEEP;
136
137    return crypto_shash_final(desc, out) ?:
138           crypto_shash_import(desc, opad) ?:
139           crypto_shash_finup(desc, out, ds, out);
140}
141
142static int hmac_finup(struct shash_desc *pdesc, const u8 *data,
143              unsigned int nbytes, u8 *out)
144{
145
146    struct crypto_shash *parent = pdesc->tfm;
147    int ds = crypto_shash_digestsize(parent);
148    int ss = crypto_shash_statesize(parent);
149    char *opad = crypto_shash_ctx_aligned(parent) + ss;
150    struct shash_desc *desc = shash_desc_ctx(pdesc);
151
152    desc->flags = pdesc->flags & CRYPTO_TFM_REQ_MAY_SLEEP;
153
154    return crypto_shash_finup(desc, data, nbytes, out) ?:
155           crypto_shash_import(desc, opad) ?:
156           crypto_shash_finup(desc, out, ds, out);
157}
158
159static int hmac_init_tfm(struct crypto_tfm *tfm)
160{
161    struct crypto_shash *parent = __crypto_shash_cast(tfm);
162    struct crypto_shash *hash;
163    struct crypto_instance *inst = (void *)tfm->__crt_alg;
164    struct crypto_shash_spawn *spawn = crypto_instance_ctx(inst);
165    struct hmac_ctx *ctx = hmac_ctx(parent);
166
167    hash = crypto_spawn_shash(spawn);
168    if (IS_ERR(hash))
169        return PTR_ERR(hash);
170
171    parent->descsize = sizeof(struct shash_desc) +
172               crypto_shash_descsize(hash);
173
174    ctx->hash = hash;
175    return 0;
176}
177
178static void hmac_exit_tfm(struct crypto_tfm *tfm)
179{
180    struct hmac_ctx *ctx = hmac_ctx(__crypto_shash_cast(tfm));
181    crypto_free_shash(ctx->hash);
182}
183
184static int hmac_create(struct crypto_template *tmpl, struct rtattr **tb)
185{
186    struct shash_instance *inst;
187    struct crypto_alg *alg;
188    struct shash_alg *salg;
189    int err;
190    int ds;
191    int ss;
192
193    err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_SHASH);
194    if (err)
195        return err;
196
197    salg = shash_attr_alg(tb[1], 0, 0);
198    if (IS_ERR(salg))
199        return PTR_ERR(salg);
200
201    err = -EINVAL;
202    ds = salg->digestsize;
203    ss = salg->statesize;
204    alg = &salg->base;
205    if (ds > alg->cra_blocksize ||
206        ss < alg->cra_blocksize)
207        goto out_put_alg;
208
209    inst = shash_alloc_instance("hmac", alg);
210    err = PTR_ERR(inst);
211    if (IS_ERR(inst))
212        goto out_put_alg;
213
214    err = crypto_init_shash_spawn(shash_instance_ctx(inst), salg,
215                      shash_crypto_instance(inst));
216    if (err)
217        goto out_free_inst;
218
219    inst->alg.base.cra_priority = alg->cra_priority;
220    inst->alg.base.cra_blocksize = alg->cra_blocksize;
221    inst->alg.base.cra_alignmask = alg->cra_alignmask;
222
223    ss = ALIGN(ss, alg->cra_alignmask + 1);
224    inst->alg.digestsize = ds;
225    inst->alg.statesize = ss;
226
227    inst->alg.base.cra_ctxsize = sizeof(struct hmac_ctx) +
228                     ALIGN(ss * 2, crypto_tfm_ctx_alignment());
229
230    inst->alg.base.cra_init = hmac_init_tfm;
231    inst->alg.base.cra_exit = hmac_exit_tfm;
232
233    inst->alg.init = hmac_init;
234    inst->alg.update = hmac_update;
235    inst->alg.final = hmac_final;
236    inst->alg.finup = hmac_finup;
237    inst->alg.export = hmac_export;
238    inst->alg.import = hmac_import;
239    inst->alg.setkey = hmac_setkey;
240
241    err = shash_register_instance(tmpl, inst);
242    if (err) {
243out_free_inst:
244        shash_free_instance(shash_crypto_instance(inst));
245    }
246
247out_put_alg:
248    crypto_mod_put(alg);
249    return err;
250}
251
252static struct crypto_template hmac_tmpl = {
253    .name = "hmac",
254    .create = hmac_create,
255    .free = shash_free_instance,
256    .module = THIS_MODULE,
257};
258
259static int __init hmac_module_init(void)
260{
261    return crypto_register_template(&hmac_tmpl);
262}
263
264static void __exit hmac_module_exit(void)
265{
266    crypto_unregister_template(&hmac_tmpl);
267}
268
269module_init(hmac_module_init);
270module_exit(hmac_module_exit);
271
272MODULE_LICENSE("GPL");
273MODULE_DESCRIPTION("HMAC hash algorithm");
274

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