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/slab.h>
27#include <linux/string.h>
28
29struct hmac_ctx {
30    struct crypto_shash *hash;
31};
32
33static inline void *align_ptr(void *p, unsigned int align)
34{
35    return (void *)ALIGN((unsigned long)p, align);
36}
37
38static 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
45static int hmac_setkey(struct crypto_shash *parent,
46               const u8 *inkey, unsigned int keylen)
47{
48    int bs = crypto_shash_blocksize(parent);
49    int ds = crypto_shash_digestsize(parent);
50    int ss = crypto_shash_statesize(parent);
51    char *ipad = crypto_shash_ctx_aligned(parent);
52    char *opad = ipad + ss;
53    struct hmac_ctx *ctx = align_ptr(opad + ss,
54                     crypto_tfm_ctx_alignment());
55    struct crypto_shash *hash = ctx->hash;
56    struct {
57        struct shash_desc shash;
58        char ctx[crypto_shash_descsize(hash)];
59    } desc;
60    unsigned int i;
61
62    desc.shash.tfm = hash;
63    desc.shash.flags = crypto_shash_get_flags(parent) &
64                CRYPTO_TFM_REQ_MAY_SLEEP;
65
66    if (keylen > bs) {
67        int err;
68
69        err = crypto_shash_digest(&desc.shash, inkey, keylen, ipad);
70        if (err)
71            return err;
72
73        keylen = ds;
74    } else
75        memcpy(ipad, inkey, keylen);
76
77    memset(ipad + keylen, 0, bs - keylen);
78    memcpy(opad, ipad, bs);
79
80    for (i = 0; i < bs; i++) {
81        ipad[i] ^= 0x36;
82        opad[i] ^= 0x5c;
83    }
84
85    return crypto_shash_init(&desc.shash) ?:
86           crypto_shash_update(&desc.shash, ipad, bs) ?:
87           crypto_shash_export(&desc.shash, ipad) ?:
88           crypto_shash_init(&desc.shash) ?:
89           crypto_shash_update(&desc.shash, opad, bs) ?:
90           crypto_shash_export(&desc.shash, opad);
91}
92
93static int hmac_export(struct shash_desc *pdesc, void *out)
94{
95    struct shash_desc *desc = shash_desc_ctx(pdesc);
96
97    desc->flags = pdesc->flags & CRYPTO_TFM_REQ_MAY_SLEEP;
98
99    return crypto_shash_export(desc, out);
100}
101
102static int hmac_import(struct shash_desc *pdesc, const void *in)
103{
104    struct shash_desc *desc = shash_desc_ctx(pdesc);
105    struct hmac_ctx *ctx = hmac_ctx(pdesc->tfm);
106
107    desc->tfm = ctx->hash;
108    desc->flags = pdesc->flags & CRYPTO_TFM_REQ_MAY_SLEEP;
109
110    return crypto_shash_import(desc, in);
111}
112
113static int hmac_init(struct shash_desc *pdesc)
114{
115    return hmac_import(pdesc, crypto_shash_ctx_aligned(pdesc->tfm));
116}
117
118static int hmac_update(struct shash_desc *pdesc,
119               const u8 *data, unsigned int nbytes)
120{
121    struct shash_desc *desc = shash_desc_ctx(pdesc);
122
123    desc->flags = pdesc->flags & CRYPTO_TFM_REQ_MAY_SLEEP;
124
125    return crypto_shash_update(desc, data, nbytes);
126}
127
128static int hmac_final(struct shash_desc *pdesc, u8 *out)
129{
130    struct crypto_shash *parent = pdesc->tfm;
131    int ds = crypto_shash_digestsize(parent);
132    int ss = crypto_shash_statesize(parent);
133    char *opad = crypto_shash_ctx_aligned(parent) + ss;
134    struct shash_desc *desc = shash_desc_ctx(pdesc);
135
136    desc->flags = pdesc->flags & CRYPTO_TFM_REQ_MAY_SLEEP;
137
138    return crypto_shash_final(desc, out) ?:
139           crypto_shash_import(desc, opad) ?:
140           crypto_shash_finup(desc, out, ds, out);
141}
142
143static int hmac_finup(struct shash_desc *pdesc, const u8 *data,
144              unsigned int nbytes, u8 *out)
145{
146
147    struct crypto_shash *parent = pdesc->tfm;
148    int ds = crypto_shash_digestsize(parent);
149    int ss = crypto_shash_statesize(parent);
150    char *opad = crypto_shash_ctx_aligned(parent) + ss;
151    struct shash_desc *desc = shash_desc_ctx(pdesc);
152
153    desc->flags = pdesc->flags & CRYPTO_TFM_REQ_MAY_SLEEP;
154
155    return crypto_shash_finup(desc, data, nbytes, out) ?:
156           crypto_shash_import(desc, opad) ?:
157           crypto_shash_finup(desc, out, ds, out);
158}
159
160static int hmac_init_tfm(struct crypto_tfm *tfm)
161{
162    struct crypto_shash *parent = __crypto_shash_cast(tfm);
163    struct crypto_shash *hash;
164    struct crypto_instance *inst = (void *)tfm->__crt_alg;
165    struct crypto_shash_spawn *spawn = crypto_instance_ctx(inst);
166    struct hmac_ctx *ctx = hmac_ctx(parent);
167
168    hash = crypto_spawn_shash(spawn);
169    if (IS_ERR(hash))
170        return PTR_ERR(hash);
171
172    parent->descsize = sizeof(struct shash_desc) +
173               crypto_shash_descsize(hash);
174
175    ctx->hash = hash;
176    return 0;
177}
178
179static void hmac_exit_tfm(struct crypto_tfm *tfm)
180{
181    struct hmac_ctx *ctx = hmac_ctx(__crypto_shash_cast(tfm));
182    crypto_free_shash(ctx->hash);
183}
184
185static int hmac_create(struct crypto_template *tmpl, struct rtattr **tb)
186{
187    struct shash_instance *inst;
188    struct crypto_alg *alg;
189    struct shash_alg *salg;
190    int err;
191    int ds;
192    int ss;
193
194    err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_SHASH);
195    if (err)
196        return err;
197
198    salg = shash_attr_alg(tb[1], 0, 0);
199    if (IS_ERR(salg))
200        return PTR_ERR(salg);
201
202    err = -EINVAL;
203    ds = salg->digestsize;
204    ss = salg->statesize;
205    alg = &salg->base;
206    if (ds > alg->cra_blocksize ||
207        ss < alg->cra_blocksize)
208        goto out_put_alg;
209
210    inst = shash_alloc_instance("hmac", alg);
211    err = PTR_ERR(inst);
212    if (IS_ERR(inst))
213        goto out_put_alg;
214
215    err = crypto_init_shash_spawn(shash_instance_ctx(inst), salg,
216                      shash_crypto_instance(inst));
217    if (err)
218        goto out_free_inst;
219
220    inst->alg.base.cra_priority = alg->cra_priority;
221    inst->alg.base.cra_blocksize = alg->cra_blocksize;
222    inst->alg.base.cra_alignmask = alg->cra_alignmask;
223
224    ss = ALIGN(ss, alg->cra_alignmask + 1);
225    inst->alg.digestsize = ds;
226    inst->alg.statesize = ss;
227
228    inst->alg.base.cra_ctxsize = sizeof(struct hmac_ctx) +
229                     ALIGN(ss * 2, crypto_tfm_ctx_alignment());
230
231    inst->alg.base.cra_init = hmac_init_tfm;
232    inst->alg.base.cra_exit = hmac_exit_tfm;
233
234    inst->alg.init = hmac_init;
235    inst->alg.update = hmac_update;
236    inst->alg.final = hmac_final;
237    inst->alg.finup = hmac_finup;
238    inst->alg.export = hmac_export;
239    inst->alg.import = hmac_import;
240    inst->alg.setkey = hmac_setkey;
241
242    err = shash_register_instance(tmpl, inst);
243    if (err) {
244out_free_inst:
245        shash_free_instance(shash_crypto_instance(inst));
246    }
247
248out_put_alg:
249    crypto_mod_put(alg);
250    return err;
251}
252
253static struct crypto_template hmac_tmpl = {
254    .name = "hmac",
255    .create = hmac_create,
256    .free = shash_free_instance,
257    .module = THIS_MODULE,
258};
259
260static int __init hmac_module_init(void)
261{
262    return crypto_register_template(&hmac_tmpl);
263}
264
265static void __exit hmac_module_exit(void)
266{
267    crypto_unregister_template(&hmac_tmpl);
268}
269
270module_init(hmac_module_init);
271module_exit(hmac_module_exit);
272
273MODULE_LICENSE("GPL");
274MODULE_DESCRIPTION("HMAC hash algorithm");
275

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