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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");