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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 | ||
28 | struct hmac_ctx { | |
29 | struct crypto_shash *hash; | |
30 | }; | |
31 | ||
32 | static inline void *align_ptr(void *p, unsigned int align) | |
33 | { | |
34 | return (void *)ALIGN((unsigned long)p, align); | |
35 | } | |
36 | ||
37 | static 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 | ||
44 | static 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 | ||
89 | static 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 | ||
98 | static 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 | ||
109 | static int hmac_init(struct shash_desc *pdesc) | |
110 | { | |
111 | return hmac_import(pdesc, crypto_shash_ctx_aligned(pdesc->tfm)); | |
112 | } | |
113 | ||
114 | static 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 | ||
124 | static 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 | ||
139 | static 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 | ||
156 | static 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 | ||
175 | static 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 | ||
181 | static 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) { | |
240 | out_free_inst: | |
241 | shash_free_instance(shash_crypto_instance(inst)); | |
242 | } | |
243 | ||
244 | out_put_alg: | |
245 | crypto_mod_put(alg); | |
246 | return err; | |
247 | } | |
248 | ||
249 | static struct crypto_template hmac_tmpl = { | |
250 | .name = "hmac", | |
251 | .create = hmac_create, | |
252 | .free = shash_free_instance, | |
253 | .module = THIS_MODULE, | |
254 | }; | |
255 | ||
256 | static int __init hmac_module_init(void) | |
257 | { | |
258 | return crypto_register_template(&hmac_tmpl); | |
259 | } | |
260 | ||
261 | static void __exit hmac_module_exit(void) | |
262 | { | |
263 | crypto_unregister_template(&hmac_tmpl); | |
264 | } | |
265 | ||
266 | module_init(hmac_module_init); | |
267 | module_exit(hmac_module_exit); | |
268 | ||
269 | MODULE_LICENSE("GPL"); | |
270 | MODULE_DESCRIPTION("HMAC hash algorithm"); | |
271 | MODULE_ALIAS_CRYPTO("hmac"); |