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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * Cryptographic API.
3 *
4 * HMAC: Keyed-Hashing for Message Authentication (RFC2104).
5 *
6 * Copyright (c) 2002 James Morris <jmorris@intercode.com.au>
Herbert Xu0796ae02006-08-21 20:50:52 +10007 * Copyright (c) 2006 Herbert Xu <herbert@gondor.apana.org.au>
Linus Torvalds1da177e2005-04-16 15:20:36 -07008 *
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
Herbert Xu0796ae02006-08-21 20:50:52 +100014 * Software Foundation; either version 2 of the License, or (at your option)
Linus Torvalds1da177e2005-04-16 15:20:36 -070015 * any later version.
16 *
17 */
Herbert Xu0796ae02006-08-21 20:50:52 +100018
19#include <crypto/algapi.h>
20#include <linux/err.h>
21#include <linux/init.h>
22#include <linux/kernel.h>
23#include <linux/module.h>
David Hardeman378f0582005-09-17 17:55:31 +100024#include <linux/scatterlist.h>
Herbert Xu0796ae02006-08-21 20:50:52 +100025#include <linux/slab.h>
26#include <linux/string.h>
27
28struct hmac_ctx {
29 struct crypto_hash *child;
30};
Linus Torvalds1da177e2005-04-16 15:20:36 -070031
Herbert Xu0796ae02006-08-21 20:50:52 +100032static inline void *align_ptr(void *p, unsigned int align)
33{
34 return (void *)ALIGN((unsigned long)p, align);
35}
36
37static inline struct hmac_ctx *hmac_ctx(struct crypto_hash *tfm)
38{
39 return align_ptr(crypto_hash_ctx_aligned(tfm) +
40 crypto_hash_blocksize(tfm) * 2 +
41 crypto_hash_digestsize(tfm), sizeof(void *));
42}
43
44static int hmac_setkey(struct crypto_hash *parent,
45 const u8 *inkey, unsigned int keylen)
46{
47 int bs = crypto_hash_blocksize(parent);
48 int ds = crypto_hash_digestsize(parent);
49 char *ipad = crypto_hash_ctx_aligned(parent);
50 char *opad = ipad + bs;
51 char *digest = opad + bs;
52 struct hmac_ctx *ctx = align_ptr(digest + ds, sizeof(void *));
53 struct crypto_hash *tfm = ctx->child;
54 unsigned int i;
55
56 if (keylen > bs) {
57 struct hash_desc desc;
58 struct scatterlist tmp;
59 int err;
60
61 desc.tfm = tfm;
62 desc.flags = crypto_hash_get_flags(parent);
63 desc.flags &= CRYPTO_TFM_REQ_MAY_SLEEP;
64 sg_set_buf(&tmp, inkey, keylen);
65
66 err = crypto_hash_digest(&desc, &tmp, keylen, digest);
67 if (err)
68 return err;
69
70 inkey = digest;
71 keylen = ds;
72 }
73
74 memcpy(ipad, inkey, keylen);
75 memset(ipad + keylen, 0, bs - keylen);
76 memcpy(opad, ipad, bs);
77
78 for (i = 0; i < bs; i++) {
79 ipad[i] ^= 0x36;
80 opad[i] ^= 0x5c;
81 }
82
83 return 0;
84}
85
86static int hmac_init(struct hash_desc *pdesc)
87{
88 struct crypto_hash *parent = pdesc->tfm;
89 int bs = crypto_hash_blocksize(parent);
90 int ds = crypto_hash_digestsize(parent);
91 char *ipad = crypto_hash_ctx_aligned(parent);
92 struct hmac_ctx *ctx = align_ptr(ipad + bs * 2 + ds, sizeof(void *));
93 struct hash_desc desc;
94 struct scatterlist tmp;
Herbert Xu73af07d2006-09-24 09:30:19 +100095 int err;
Herbert Xu0796ae02006-08-21 20:50:52 +100096
97 desc.tfm = ctx->child;
98 desc.flags = pdesc->flags & CRYPTO_TFM_REQ_MAY_SLEEP;
99 sg_set_buf(&tmp, ipad, bs);
100
Herbert Xu73af07d2006-09-24 09:30:19 +1000101 err = crypto_hash_init(&desc);
102 if (unlikely(err))
103 return err;
104
105 return crypto_hash_update(&desc, &tmp, bs);
Herbert Xu0796ae02006-08-21 20:50:52 +1000106}
107
108static int hmac_update(struct hash_desc *pdesc,
109 struct scatterlist *sg, unsigned int nbytes)
110{
111 struct hmac_ctx *ctx = hmac_ctx(pdesc->tfm);
112 struct hash_desc desc;
113
114 desc.tfm = ctx->child;
115 desc.flags = pdesc->flags & CRYPTO_TFM_REQ_MAY_SLEEP;
116
117 return crypto_hash_update(&desc, sg, nbytes);
118}
119
120static int hmac_final(struct hash_desc *pdesc, u8 *out)
121{
122 struct crypto_hash *parent = pdesc->tfm;
123 int bs = crypto_hash_blocksize(parent);
124 int ds = crypto_hash_digestsize(parent);
125 char *opad = crypto_hash_ctx_aligned(parent) + bs;
126 char *digest = opad + bs;
127 struct hmac_ctx *ctx = align_ptr(digest + ds, sizeof(void *));
128 struct hash_desc desc;
129 struct scatterlist tmp;
Herbert Xu73af07d2006-09-24 09:30:19 +1000130 int err;
Herbert Xu0796ae02006-08-21 20:50:52 +1000131
132 desc.tfm = ctx->child;
133 desc.flags = pdesc->flags & CRYPTO_TFM_REQ_MAY_SLEEP;
134 sg_set_buf(&tmp, opad, bs + ds);
135
Herbert Xu73af07d2006-09-24 09:30:19 +1000136 err = crypto_hash_final(&desc, digest);
137 if (unlikely(err))
138 return err;
139
140 return crypto_hash_digest(&desc, &tmp, bs + ds, out);
Herbert Xu0796ae02006-08-21 20:50:52 +1000141}
142
143static int hmac_digest(struct hash_desc *pdesc, struct scatterlist *sg,
144 unsigned int nbytes, u8 *out)
145{
146 struct crypto_hash *parent = pdesc->tfm;
147 int bs = crypto_hash_blocksize(parent);
148 int ds = crypto_hash_digestsize(parent);
149 char *ipad = crypto_hash_ctx_aligned(parent);
150 char *opad = ipad + bs;
151 char *digest = opad + bs;
152 struct hmac_ctx *ctx = align_ptr(digest + ds, sizeof(void *));
153 struct hash_desc desc;
154 struct scatterlist sg1[2];
155 struct scatterlist sg2[1];
Herbert Xu73af07d2006-09-24 09:30:19 +1000156 int err;
Herbert Xu0796ae02006-08-21 20:50:52 +1000157
158 desc.tfm = ctx->child;
159 desc.flags = pdesc->flags & CRYPTO_TFM_REQ_MAY_SLEEP;
160
161 sg_set_buf(sg1, ipad, bs);
162 sg1[1].page = (void *)sg;
163 sg1[1].length = 0;
164 sg_set_buf(sg2, opad, bs + ds);
165
Herbert Xu73af07d2006-09-24 09:30:19 +1000166 err = crypto_hash_digest(&desc, sg1, nbytes + bs, digest);
167 if (unlikely(err))
168 return err;
169
170 return crypto_hash_digest(&desc, sg2, bs + ds, out);
Herbert Xu0796ae02006-08-21 20:50:52 +1000171}
172
173static int hmac_init_tfm(struct crypto_tfm *tfm)
174{
Herbert Xu2e306ee2006-12-17 10:05:58 +1100175 struct crypto_hash *hash;
Herbert Xu0796ae02006-08-21 20:50:52 +1000176 struct crypto_instance *inst = (void *)tfm->__crt_alg;
177 struct crypto_spawn *spawn = crypto_instance_ctx(inst);
178 struct hmac_ctx *ctx = hmac_ctx(__crypto_hash_cast(tfm));
179
Herbert Xu2e306ee2006-12-17 10:05:58 +1100180 hash = crypto_spawn_hash(spawn);
181 if (IS_ERR(hash))
182 return PTR_ERR(hash);
Herbert Xu0796ae02006-08-21 20:50:52 +1000183
Herbert Xu2e306ee2006-12-17 10:05:58 +1100184 ctx->child = hash;
Herbert Xu0796ae02006-08-21 20:50:52 +1000185 return 0;
186}
187
188static void hmac_exit_tfm(struct crypto_tfm *tfm)
189{
190 struct hmac_ctx *ctx = hmac_ctx(__crypto_hash_cast(tfm));
191 crypto_free_hash(ctx->child);
192}
193
194static void hmac_free(struct crypto_instance *inst)
195{
196 crypto_drop_spawn(crypto_instance_ctx(inst));
197 kfree(inst);
198}
199
200static struct crypto_instance *hmac_alloc(void *param, unsigned int len)
201{
202 struct crypto_instance *inst;
203 struct crypto_alg *alg;
204
205 alg = crypto_get_attr_alg(param, len, CRYPTO_ALG_TYPE_HASH,
206 CRYPTO_ALG_TYPE_HASH_MASK | CRYPTO_ALG_ASYNC);
207 if (IS_ERR(alg))
208 return ERR_PTR(PTR_ERR(alg));
209
210 inst = crypto_alloc_instance("hmac", alg);
211 if (IS_ERR(inst))
212 goto out_put_alg;
213
214 inst->alg.cra_flags = CRYPTO_ALG_TYPE_HASH;
215 inst->alg.cra_priority = alg->cra_priority;
216 inst->alg.cra_blocksize = alg->cra_blocksize;
217 inst->alg.cra_alignmask = alg->cra_alignmask;
218 inst->alg.cra_type = &crypto_hash_type;
219
220 inst->alg.cra_hash.digestsize =
221 (alg->cra_flags & CRYPTO_ALG_TYPE_MASK) ==
222 CRYPTO_ALG_TYPE_HASH ? alg->cra_hash.digestsize :
223 alg->cra_digest.dia_digestsize;
224
225 inst->alg.cra_ctxsize = sizeof(struct hmac_ctx) +
226 ALIGN(inst->alg.cra_blocksize * 2 +
227 inst->alg.cra_hash.digestsize,
228 sizeof(void *));
229
230 inst->alg.cra_init = hmac_init_tfm;
231 inst->alg.cra_exit = hmac_exit_tfm;
232
233 inst->alg.cra_hash.init = hmac_init;
234 inst->alg.cra_hash.update = hmac_update;
235 inst->alg.cra_hash.final = hmac_final;
236 inst->alg.cra_hash.digest = hmac_digest;
237 inst->alg.cra_hash.setkey = hmac_setkey;
238
239out_put_alg:
240 crypto_mod_put(alg);
241 return inst;
242}
243
244static struct crypto_template hmac_tmpl = {
245 .name = "hmac",
246 .alloc = hmac_alloc,
247 .free = hmac_free,
248 .module = THIS_MODULE,
249};
250
251static int __init hmac_module_init(void)
252{
253 return crypto_register_template(&hmac_tmpl);
254}
255
256static void __exit hmac_module_exit(void)
257{
258 crypto_unregister_template(&hmac_tmpl);
259}
260
261module_init(hmac_module_init);
262module_exit(hmac_module_exit);
263
264MODULE_LICENSE("GPL");
265MODULE_DESCRIPTION("HMAC hash algorithm");