crypto: hmac - Fix incorrect error value when creating instance
[linux-2.6.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/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
29 struct hmac_ctx {
30         struct shash_desc *desc;
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_blocksize(tfm) * 2 +
42                          crypto_shash_digestsize(tfm),
43                          crypto_tfm_ctx_alignment());
44 }
45
46 static int hmac_setkey(struct crypto_shash *parent,
47                        const u8 *inkey, unsigned int keylen)
48 {
49         int bs = crypto_shash_blocksize(parent);
50         int ds = crypto_shash_digestsize(parent);
51         char *ipad = crypto_shash_ctx_aligned(parent);
52         char *opad = ipad + bs;
53         char *digest = opad + bs;
54         struct hmac_ctx *ctx = align_ptr(digest + ds,
55                                          crypto_tfm_ctx_alignment());
56         unsigned int i;
57
58         if (keylen > bs) {
59                 int err;
60
61                 ctx->desc->flags = crypto_shash_get_flags(parent) &
62                                    CRYPTO_TFM_REQ_MAY_SLEEP;
63
64                 err = crypto_shash_digest(ctx->desc, inkey, keylen, digest);
65                 if (err)
66                         return err;
67
68                 inkey = digest;
69                 keylen = ds;
70         }
71
72         memcpy(ipad, inkey, keylen);
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 0;
82 }
83
84 static int hmac_init(struct shash_desc *pdesc)
85 {
86         struct crypto_shash *parent = pdesc->tfm;
87         int bs = crypto_shash_blocksize(parent);
88         int ds = crypto_shash_digestsize(parent);
89         char *ipad = crypto_shash_ctx_aligned(parent);
90         struct hmac_ctx *ctx = align_ptr(ipad + bs * 2 + ds,
91                                          crypto_tfm_ctx_alignment());
92         struct shash_desc *desc = shash_desc_ctx(pdesc);
93
94         desc->tfm = ctx->desc->tfm;
95         desc->flags = pdesc->flags & CRYPTO_TFM_REQ_MAY_SLEEP;
96
97         return crypto_shash_init(desc) ?:
98                crypto_shash_update(desc, ipad, bs);
99 }
100
101 static int hmac_update(struct shash_desc *pdesc,
102                        const u8 *data, unsigned int nbytes)
103 {
104         struct shash_desc *desc = shash_desc_ctx(pdesc);
105
106         desc->flags = pdesc->flags & CRYPTO_TFM_REQ_MAY_SLEEP;
107
108         return crypto_shash_update(desc, data, nbytes);
109 }
110
111 static int hmac_final(struct shash_desc *pdesc, u8 *out)
112 {
113         struct crypto_shash *parent = pdesc->tfm;
114         int bs = crypto_shash_blocksize(parent);
115         int ds = crypto_shash_digestsize(parent);
116         char *opad = crypto_shash_ctx_aligned(parent) + bs;
117         char *digest = opad + bs;
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_final(desc, digest) ?:
123                crypto_shash_digest(desc, opad, bs + ds, out);
124 }
125
126 static int hmac_finup(struct shash_desc *pdesc, const u8 *data,
127                       unsigned int nbytes, u8 *out)
128 {
129
130         struct crypto_shash *parent = pdesc->tfm;
131         int bs = crypto_shash_blocksize(parent);
132         int ds = crypto_shash_digestsize(parent);
133         char *opad = crypto_shash_ctx_aligned(parent) + bs;
134         char *digest = opad + bs;
135         struct shash_desc *desc = shash_desc_ctx(pdesc);
136
137         desc->flags = pdesc->flags & CRYPTO_TFM_REQ_MAY_SLEEP;
138
139         return crypto_shash_finup(desc, data, nbytes, digest) ?:
140                crypto_shash_digest(desc, opad, bs + ds, out);
141 }
142
143 static int hmac_init_tfm(struct crypto_tfm *tfm)
144 {
145         struct crypto_shash *parent = __crypto_shash_cast(tfm);
146         struct crypto_shash *hash;
147         struct crypto_instance *inst = (void *)tfm->__crt_alg;
148         struct crypto_shash_spawn *spawn = crypto_instance_ctx(inst);
149         struct hmac_ctx *ctx = hmac_ctx(parent);
150
151         hash = crypto_spawn_shash(spawn);
152         if (IS_ERR(hash))
153                 return PTR_ERR(hash);
154
155         parent->descsize = sizeof(struct shash_desc) +
156                            crypto_shash_descsize(hash);
157
158         ctx->desc = kmalloc(parent->descsize, GFP_KERNEL);
159         if (!ctx->desc) {
160                 crypto_free_shash(hash);
161                 return -ENOMEM;
162         }
163
164         ctx->desc->tfm = hash;
165         return 0;
166 }
167
168 static void hmac_exit_tfm(struct crypto_tfm *tfm)
169 {
170         struct hmac_ctx *ctx = hmac_ctx(__crypto_shash_cast(tfm));
171         crypto_free_shash(ctx->desc->tfm);
172         kzfree(ctx->desc);
173 }
174
175 static int hmac_create(struct crypto_template *tmpl, struct rtattr **tb)
176 {
177         struct shash_instance *inst;
178         struct crypto_alg *alg;
179         struct shash_alg *salg;
180         int err;
181         int ds;
182
183         err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_SHASH);
184         if (err)
185                 return err;
186
187         salg = shash_attr_alg(tb[1], 0, 0);
188         if (IS_ERR(salg))
189                 return PTR_ERR(salg);
190
191         err = -EINVAL;
192         ds = salg->digestsize;
193         alg = &salg->base;
194         if (ds > alg->cra_blocksize)
195                 goto out_put_alg;
196
197         inst = shash_alloc_instance("hmac", alg);
198         err = PTR_ERR(inst);
199         if (IS_ERR(inst))
200                 goto out_put_alg;
201
202         err = crypto_init_shash_spawn(shash_instance_ctx(inst), salg,
203                                       shash_crypto_instance(inst));
204         if (err)
205                 goto out_free_inst;
206
207         inst->alg.base.cra_priority = alg->cra_priority;
208         inst->alg.base.cra_blocksize = alg->cra_blocksize;
209         inst->alg.base.cra_alignmask = alg->cra_alignmask;
210
211         inst->alg.digestsize = ds;
212
213         inst->alg.base.cra_ctxsize = sizeof(struct hmac_ctx) +
214                                      ALIGN(alg->cra_blocksize * 2 + ds,
215                                            crypto_tfm_ctx_alignment());
216
217         inst->alg.base.cra_init = hmac_init_tfm;
218         inst->alg.base.cra_exit = hmac_exit_tfm;
219
220         inst->alg.init = hmac_init;
221         inst->alg.update = hmac_update;
222         inst->alg.final = hmac_final;
223         inst->alg.finup = hmac_finup;
224         inst->alg.setkey = hmac_setkey;
225
226         err = shash_register_instance(tmpl, inst);
227         if (err) {
228 out_free_inst:
229                 shash_free_instance(shash_crypto_instance(inst));
230         }
231
232 out_put_alg:
233         crypto_mod_put(alg);
234         return err;
235 }
236
237 static struct crypto_template hmac_tmpl = {
238         .name = "hmac",
239         .create = hmac_create,
240         .free = shash_free_instance,
241         .module = THIS_MODULE,
242 };
243
244 static int __init hmac_module_init(void)
245 {
246         return crypto_register_template(&hmac_tmpl);
247 }
248
249 static void __exit hmac_module_exit(void)
250 {
251         crypto_unregister_template(&hmac_tmpl);
252 }
253
254 module_init(hmac_module_init);
255 module_exit(hmac_module_exit);
256
257 MODULE_LICENSE("GPL");
258 MODULE_DESCRIPTION("HMAC hash algorithm");