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    SHASH_DESC_ON_STACK(shash, hash);
56    unsigned int i;
57
58    shash->tfm = hash;
59    shash->flags = crypto_shash_get_flags(parent)
60        & CRYPTO_TFM_REQ_MAY_SLEEP;
61
62    if (keylen > bs) {
63        int err;
64
65        err = crypto_shash_digest(shash, inkey, keylen, ipad);
66        if (err)
67            return err;
68
69        keylen = ds;
70    } else
71        memcpy(ipad, inkey, keylen);
72
73    memset(ipad + keylen, 0, bs - keylen);
74    memcpy(opad, ipad, bs);
75
76    for (i = 0; i < bs; i++) {
77        ipad[i] ^= 0x36;
78        opad[i] ^= 0x5c;
79    }
80
81    return crypto_shash_init(shash) ?:
82           crypto_shash_update(shash, ipad, bs) ?:
83           crypto_shash_export(shash, ipad) ?:
84           crypto_shash_init(shash) ?:
85           crypto_shash_update(shash, opad, bs) ?:
86           crypto_shash_export(shash, opad);
87}
88
89static int hmac_export(struct shash_desc *pdesc, void *out)
90{
91    struct shash_desc *desc = shash_desc_ctx(pdesc);
92
93    desc->flags = pdesc->flags & CRYPTO_TFM_REQ_MAY_SLEEP;
94
95    return crypto_shash_export(desc, out);
96}
97
98static int hmac_import(struct shash_desc *pdesc, const void *in)
99{
100    struct shash_desc *desc = shash_desc_ctx(pdesc);
101    struct hmac_ctx *ctx = hmac_ctx(pdesc->tfm);
102
103    desc->tfm = ctx->hash;
104    desc->flags = pdesc->flags & CRYPTO_TFM_REQ_MAY_SLEEP;
105
106    return crypto_shash_import(desc, in);
107}
108
109static int hmac_init(struct shash_desc *pdesc)
110{
111    return hmac_import(pdesc, crypto_shash_ctx_aligned(pdesc->tfm));
112}
113
114static int hmac_update(struct shash_desc *pdesc,
115               const u8 *data, unsigned int nbytes)
116{
117    struct shash_desc *desc = shash_desc_ctx(pdesc);
118
119    desc->flags = pdesc->flags & CRYPTO_TFM_REQ_MAY_SLEEP;
120
121    return crypto_shash_update(desc, data, nbytes);
122}
123
124static int hmac_final(struct shash_desc *pdesc, u8 *out)
125{
126    struct crypto_shash *parent = pdesc->tfm;
127    int ds = crypto_shash_digestsize(parent);
128    int ss = crypto_shash_statesize(parent);
129    char *opad = crypto_shash_ctx_aligned(parent) + ss;
130    struct shash_desc *desc = shash_desc_ctx(pdesc);
131
132    desc->flags = pdesc->flags & CRYPTO_TFM_REQ_MAY_SLEEP;
133
134    return crypto_shash_final(desc, out) ?:
135           crypto_shash_import(desc, opad) ?:
136           crypto_shash_finup(desc, out, ds, out);
137}
138
139static int hmac_finup(struct shash_desc *pdesc, const u8 *data,
140              unsigned int nbytes, u8 *out)
141{
142
143    struct crypto_shash *parent = pdesc->tfm;
144    int ds = crypto_shash_digestsize(parent);
145    int ss = crypto_shash_statesize(parent);
146    char *opad = crypto_shash_ctx_aligned(parent) + ss;
147    struct shash_desc *desc = shash_desc_ctx(pdesc);
148
149    desc->flags = pdesc->flags & CRYPTO_TFM_REQ_MAY_SLEEP;
150
151    return crypto_shash_finup(desc, data, nbytes, out) ?:
152           crypto_shash_import(desc, opad) ?:
153           crypto_shash_finup(desc, out, ds, out);
154}
155
156static int hmac_init_tfm(struct crypto_tfm *tfm)
157{
158    struct crypto_shash *parent = __crypto_shash_cast(tfm);
159    struct crypto_shash *hash;
160    struct crypto_instance *inst = (void *)tfm->__crt_alg;
161    struct crypto_shash_spawn *spawn = crypto_instance_ctx(inst);
162    struct hmac_ctx *ctx = hmac_ctx(parent);
163
164    hash = crypto_spawn_shash(spawn);
165    if (IS_ERR(hash))
166        return PTR_ERR(hash);
167
168    parent->descsize = sizeof(struct shash_desc) +
169               crypto_shash_descsize(hash);
170
171    ctx->hash = hash;
172    return 0;
173}
174
175static void hmac_exit_tfm(struct crypto_tfm *tfm)
176{
177    struct hmac_ctx *ctx = hmac_ctx(__crypto_shash_cast(tfm));
178    crypto_free_shash(ctx->hash);
179}
180
181static int hmac_create(struct crypto_template *tmpl, struct rtattr **tb)
182{
183    struct shash_instance *inst;
184    struct crypto_alg *alg;
185    struct shash_alg *salg;
186    int err;
187    int ds;
188    int ss;
189
190    err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_SHASH);
191    if (err)
192        return err;
193
194    salg = shash_attr_alg(tb[1], 0, 0);
195    if (IS_ERR(salg))
196        return PTR_ERR(salg);
197
198    err = -EINVAL;
199    ds = salg->digestsize;
200    ss = salg->statesize;
201    alg = &salg->base;
202    if (ds > alg->cra_blocksize ||
203        ss < alg->cra_blocksize)
204        goto out_put_alg;
205
206    inst = shash_alloc_instance("hmac", alg);
207    err = PTR_ERR(inst);
208    if (IS_ERR(inst))
209        goto out_put_alg;
210
211    err = crypto_init_shash_spawn(shash_instance_ctx(inst), salg,
212                      shash_crypto_instance(inst));
213    if (err)
214        goto out_free_inst;
215
216    inst->alg.base.cra_priority = alg->cra_priority;
217    inst->alg.base.cra_blocksize = alg->cra_blocksize;
218    inst->alg.base.cra_alignmask = alg->cra_alignmask;
219
220    ss = ALIGN(ss, alg->cra_alignmask + 1);
221    inst->alg.digestsize = ds;
222    inst->alg.statesize = ss;
223
224    inst->alg.base.cra_ctxsize = sizeof(struct hmac_ctx) +
225                     ALIGN(ss * 2, crypto_tfm_ctx_alignment());
226
227    inst->alg.base.cra_init = hmac_init_tfm;
228    inst->alg.base.cra_exit = hmac_exit_tfm;
229
230    inst->alg.init = hmac_init;
231    inst->alg.update = hmac_update;
232    inst->alg.final = hmac_final;
233    inst->alg.finup = hmac_finup;
234    inst->alg.export = hmac_export;
235    inst->alg.import = hmac_import;
236    inst->alg.setkey = hmac_setkey;
237
238    err = shash_register_instance(tmpl, inst);
239    if (err) {
240out_free_inst:
241        shash_free_instance(shash_crypto_instance(inst));
242    }
243
244out_put_alg:
245    crypto_mod_put(alg);
246    return err;
247}
248
249static struct crypto_template hmac_tmpl = {
250    .name = "hmac",
251    .create = hmac_create,
252    .free = shash_free_instance,
253    .module = THIS_MODULE,
254};
255
256static int __init hmac_module_init(void)
257{
258    return crypto_register_template(&hmac_tmpl);
259}
260
261static void __exit hmac_module_exit(void)
262{
263    crypto_unregister_template(&hmac_tmpl);
264}
265
266module_init(hmac_module_init);
267module_exit(hmac_module_exit);
268
269MODULE_LICENSE("GPL");
270MODULE_DESCRIPTION("HMAC hash algorithm");
271

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