drm: Begin an API for in-kernel clients
[linux-2.6-microblaze.git] / 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/hmac.h>
20 #include <crypto/internal/hash.h>
21 #include <crypto/scatterwalk.h>
22 #include <linux/err.h>
23 #include <linux/init.h>
24 #include <linux/kernel.h>
25 #include <linux/module.h>
26 #include <linux/scatterlist.h>
27 #include <linux/string.h>
28
29 struct hmac_ctx {
30         struct crypto_shash *hash;
31 };
32
33 static inline void *align_ptr(void *p, unsigned int align)
34 {
35         return (void *)ALIGN((unsigned long)p, align);
36 }
37
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                        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         SHASH_DESC_ON_STACK(shash, hash);
57         unsigned int i;
58
59         shash->tfm = hash;
60         shash->flags = crypto_shash_get_flags(parent)
61                 & CRYPTO_TFM_REQ_MAY_SLEEP;
62
63         if (keylen > bs) {
64                 int err;
65
66                 err = crypto_shash_digest(shash, inkey, keylen, ipad);
67                 if (err)
68                         return err;
69
70                 keylen = ds;
71         } else
72                 memcpy(ipad, inkey, keylen);
73
74         memset(ipad + keylen, 0, bs - keylen);
75         memcpy(opad, ipad, bs);
76
77         for (i = 0; i < bs; i++) {
78                 ipad[i] ^= HMAC_IPAD_VALUE;
79                 opad[i] ^= HMAC_OPAD_VALUE;
80         }
81
82         return crypto_shash_init(shash) ?:
83                crypto_shash_update(shash, ipad, bs) ?:
84                crypto_shash_export(shash, ipad) ?:
85                crypto_shash_init(shash) ?:
86                crypto_shash_update(shash, opad, bs) ?:
87                crypto_shash_export(shash, opad);
88 }
89
90 static int hmac_export(struct shash_desc *pdesc, void *out)
91 {
92         struct shash_desc *desc = shash_desc_ctx(pdesc);
93
94         desc->flags = pdesc->flags & CRYPTO_TFM_REQ_MAY_SLEEP;
95
96         return crypto_shash_export(desc, out);
97 }
98
99 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         desc->flags = pdesc->flags & CRYPTO_TFM_REQ_MAY_SLEEP;
106
107         return crypto_shash_import(desc, in);
108 }
109
110 static int hmac_init(struct shash_desc *pdesc)
111 {
112         return hmac_import(pdesc, crypto_shash_ctx_aligned(pdesc->tfm));
113 }
114
115 static int hmac_update(struct shash_desc *pdesc,
116                        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         struct crypto_shash *parent = pdesc->tfm;
128         int ds = crypto_shash_digestsize(parent);
129         int ss = crypto_shash_statesize(parent);
130         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         return crypto_shash_final(desc, out) ?:
136                crypto_shash_import(desc, opad) ?:
137                crypto_shash_finup(desc, out, ds, out);
138 }
139
140 static int hmac_finup(struct shash_desc *pdesc, const u8 *data,
141                       unsigned int nbytes, u8 *out)
142 {
143
144         struct crypto_shash *parent = pdesc->tfm;
145         int ds = crypto_shash_digestsize(parent);
146         int ss = crypto_shash_statesize(parent);
147         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         return crypto_shash_finup(desc, data, nbytes, out) ?:
153                crypto_shash_import(desc, opad) ?:
154                crypto_shash_finup(desc, out, ds, out);
155 }
156
157 static int hmac_init_tfm(struct crypto_tfm *tfm)
158 {
159         struct crypto_shash *parent = __crypto_shash_cast(tfm);
160         struct crypto_shash *hash;
161         struct crypto_instance *inst = (void *)tfm->__crt_alg;
162         struct crypto_shash_spawn *spawn = crypto_instance_ctx(inst);
163         struct hmac_ctx *ctx = hmac_ctx(parent);
164
165         hash = crypto_spawn_shash(spawn);
166         if (IS_ERR(hash))
167                 return PTR_ERR(hash);
168
169         parent->descsize = sizeof(struct shash_desc) +
170                            crypto_shash_descsize(hash);
171
172         ctx->hash = hash;
173         return 0;
174 }
175
176 static void hmac_exit_tfm(struct crypto_tfm *tfm)
177 {
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                 return err;
194
195         salg = shash_attr_alg(tb[1], 0, 0);
196         if (IS_ERR(salg))
197                 return PTR_ERR(salg);
198         alg = &salg->base;
199
200         /* The underlying hash algorithm must be unkeyed */
201         err = -EINVAL;
202         if (crypto_shash_alg_has_setkey(salg))
203                 goto out_put_alg;
204
205         ds = salg->digestsize;
206         ss = salg->statesize;
207         if (ds > alg->cra_blocksize ||
208             ss < alg->cra_blocksize)
209                 goto out_put_alg;
210
211         inst = shash_alloc_instance("hmac", alg);
212         err = PTR_ERR(inst);
213         if (IS_ERR(inst))
214                 goto out_put_alg;
215
216         err = crypto_init_shash_spawn(shash_instance_ctx(inst), salg,
217                                       shash_crypto_instance(inst));
218         if (err)
219                 goto out_free_inst;
220
221         inst->alg.base.cra_priority = alg->cra_priority;
222         inst->alg.base.cra_blocksize = alg->cra_blocksize;
223         inst->alg.base.cra_alignmask = alg->cra_alignmask;
224
225         ss = ALIGN(ss, alg->cra_alignmask + 1);
226         inst->alg.digestsize = ds;
227         inst->alg.statesize = ss;
228
229         inst->alg.base.cra_ctxsize = sizeof(struct hmac_ctx) +
230                                      ALIGN(ss * 2, crypto_tfm_ctx_alignment());
231
232         inst->alg.base.cra_init = hmac_init_tfm;
233         inst->alg.base.cra_exit = hmac_exit_tfm;
234
235         inst->alg.init = hmac_init;
236         inst->alg.update = hmac_update;
237         inst->alg.final = hmac_final;
238         inst->alg.finup = hmac_finup;
239         inst->alg.export = hmac_export;
240         inst->alg.import = hmac_import;
241         inst->alg.setkey = hmac_setkey;
242
243         err = shash_register_instance(tmpl, inst);
244         if (err) {
245 out_free_inst:
246                 shash_free_instance(shash_crypto_instance(inst));
247         }
248
249 out_put_alg:
250         crypto_mod_put(alg);
251         return err;
252 }
253
254 static struct crypto_template hmac_tmpl = {
255         .name = "hmac",
256         .create = hmac_create,
257         .free = shash_free_instance,
258         .module = THIS_MODULE,
259 };
260
261 static int __init hmac_module_init(void)
262 {
263         return crypto_register_template(&hmac_tmpl);
264 }
265
266 static void __exit hmac_module_exit(void)
267 {
268         crypto_unregister_template(&hmac_tmpl);
269 }
270
271 module_init(hmac_module_init);
272 module_exit(hmac_module_exit);
273
274 MODULE_LICENSE("GPL");
275 MODULE_DESCRIPTION("HMAC hash algorithm");
276 MODULE_ALIAS_CRYPTO("hmac");