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 crypto_hash *child;
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_hash *tfm)
39 {
40 return align_ptr(crypto_hash_ctx_aligned(tfm) +
41 crypto_hash_blocksize(tfm) * 2 +
42 crypto_hash_digestsize(tfm), sizeof(void *));
43 }
44
45 static int hmac_setkey(struct crypto_hash *parent,
46 const u8 *inkey, unsigned int keylen)
47 {
48 int bs = crypto_hash_blocksize(parent);
49 int ds = crypto_hash_digestsize(parent);
50 char *ipad = crypto_hash_ctx_aligned(parent);
51 char *opad = ipad + bs;
52 char *digest = opad + bs;
53 struct hmac_ctx *ctx = align_ptr(digest + ds, sizeof(void *));
54 struct crypto_hash *tfm = ctx->child;
55 unsigned int i;
56
57 if (keylen > bs) {
58 struct hash_desc desc;
59 struct scatterlist tmp;
60 int tmplen;
61 int err;
62
63 desc.tfm = tfm;
64 desc.flags = crypto_hash_get_flags(parent);
65 desc.flags &= CRYPTO_TFM_REQ_MAY_SLEEP;
66
67 err = crypto_hash_init(&desc);
68 if (err)
69 return err;
70
71 tmplen = bs * 2 + ds;
72 sg_init_one(&tmp, ipad, tmplen);
73
74 for (; keylen > tmplen; inkey += tmplen, keylen -= tmplen) {
75 memcpy(ipad, inkey, tmplen);
76 err = crypto_hash_update(&desc, &tmp, tmplen);
77 if (err)
78 return err;
79 }
80
81 if (keylen) {
82 memcpy(ipad, inkey, keylen);
83 err = crypto_hash_update(&desc, &tmp, keylen);
84 if (err)
85 return err;
86 }
87
88 err = crypto_hash_final(&desc, digest);
89 if (err)
90 return err;
91
92 inkey = digest;
93 keylen = ds;
94 }
95
96 memcpy(ipad, inkey, keylen);
97 memset(ipad + keylen, 0, bs - keylen);
98 memcpy(opad, ipad, bs);
99
100 for (i = 0; i < bs; i++) {
101 ipad[i] ^= 0x36;
102 opad[i] ^= 0x5c;
103 }
104
105 return 0;
106 }
107
108 static int hmac_init(struct hash_desc *pdesc)
109 {
110 struct crypto_hash *parent = pdesc->tfm;
111 int bs = crypto_hash_blocksize(parent);
112 int ds = crypto_hash_digestsize(parent);
113 char *ipad = crypto_hash_ctx_aligned(parent);
114 struct hmac_ctx *ctx = align_ptr(ipad + bs * 2 + ds, sizeof(void *));
115 struct hash_desc desc;
116 struct scatterlist tmp;
117 int err;
118
119 desc.tfm = ctx->child;
120 desc.flags = pdesc->flags & CRYPTO_TFM_REQ_MAY_SLEEP;
121 sg_init_one(&tmp, ipad, bs);
122
123 err = crypto_hash_init(&desc);
124 if (unlikely(err))
125 return err;
126
127 return crypto_hash_update(&desc, &tmp, bs);
128 }
129
130 static int hmac_update(struct hash_desc *pdesc,
131 struct scatterlist *sg, unsigned int nbytes)
132 {
133 struct hmac_ctx *ctx = hmac_ctx(pdesc->tfm);
134 struct hash_desc desc;
135
136 desc.tfm = ctx->child;
137 desc.flags = pdesc->flags & CRYPTO_TFM_REQ_MAY_SLEEP;
138
139 return crypto_hash_update(&desc, sg, nbytes);
140 }
141
142 static int hmac_final(struct hash_desc *pdesc, u8 *out)
143 {
144 struct crypto_hash *parent = pdesc->tfm;
145 int bs = crypto_hash_blocksize(parent);
146 int ds = crypto_hash_digestsize(parent);
147 char *opad = crypto_hash_ctx_aligned(parent) + bs;
148 char *digest = opad + bs;
149 struct hmac_ctx *ctx = align_ptr(digest + ds, sizeof(void *));
150 struct hash_desc desc;
151 struct scatterlist tmp;
152 int err;
153
154 desc.tfm = ctx->child;
155 desc.flags = pdesc->flags & CRYPTO_TFM_REQ_MAY_SLEEP;
156 sg_init_one(&tmp, opad, bs + ds);
157
158 err = crypto_hash_final(&desc, digest);
159 if (unlikely(err))
160 return err;
161
162 return crypto_hash_digest(&desc, &tmp, bs + ds, out);
163 }
164
165 static int hmac_digest(struct hash_desc *pdesc, struct scatterlist *sg,
166 unsigned int nbytes, u8 *out)
167 {
168 struct crypto_hash *parent = pdesc->tfm;
169 int bs = crypto_hash_blocksize(parent);
170 int ds = crypto_hash_digestsize(parent);
171 char *ipad = crypto_hash_ctx_aligned(parent);
172 char *opad = ipad + bs;
173 char *digest = opad + bs;
174 struct hmac_ctx *ctx = align_ptr(digest + ds, sizeof(void *));
175 struct hash_desc desc;
176 struct scatterlist sg1[2];
177 struct scatterlist sg2[1];
178 int err;
179
180 desc.tfm = ctx->child;
181 desc.flags = pdesc->flags & CRYPTO_TFM_REQ_MAY_SLEEP;
182
183 sg_init_table(sg1, 2);
184 sg_set_buf(sg1, ipad, bs);
185 scatterwalk_sg_chain(sg1, 2, sg);
186
187 sg_init_table(sg2, 1);
188 sg_set_buf(sg2, opad, bs + ds);
189
190 err = crypto_hash_digest(&desc, sg1, nbytes + bs, digest);
191 if (unlikely(err))
192 return err;
193
194 return crypto_hash_digest(&desc, sg2, bs + ds, out);
195 }
196
197 static int hmac_init_tfm(struct crypto_tfm *tfm)
198 {
199 struct crypto_hash *hash;
200 struct crypto_instance *inst = (void *)tfm->__crt_alg;
201 struct crypto_spawn *spawn = crypto_instance_ctx(inst);
202 struct hmac_ctx *ctx = hmac_ctx(__crypto_hash_cast(tfm));
203
204 hash = crypto_spawn_hash(spawn);
205 if (IS_ERR(hash))
206 return PTR_ERR(hash);
207
208 ctx->child = hash;
209 return 0;
210 }
211
212 static void hmac_exit_tfm(struct crypto_tfm *tfm)
213 {
214 struct hmac_ctx *ctx = hmac_ctx(__crypto_hash_cast(tfm));
215 crypto_free_hash(ctx->child);
216 }
217
218 static void hmac_free(struct crypto_instance *inst)
219 {
220 crypto_drop_spawn(crypto_instance_ctx(inst));
221 kfree(inst);
222 }
223
224 static struct crypto_instance *hmac_alloc(struct rtattr **tb)
225 {
226 struct crypto_instance *inst;
227 struct crypto_alg *alg;
228 int err;
229 int ds;
230
231 err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_HASH);
232 if (err)
233 return ERR_PTR(err);
234
235 alg = crypto_get_attr_alg(tb, CRYPTO_ALG_TYPE_HASH,
236 CRYPTO_ALG_TYPE_HASH_MASK);
237 if (IS_ERR(alg))
238 return ERR_CAST(alg);
239
240 inst = ERR_PTR(-EINVAL);
241 ds = alg->cra_type == &crypto_hash_type ?
242 alg->cra_hash.digestsize :
243 alg->cra_type ?
244 __crypto_shash_alg(alg)->digestsize :
245 alg->cra_digest.dia_digestsize;
246 if (ds > alg->cra_blocksize)
247 goto out_put_alg;
248
249 inst = crypto_alloc_instance("hmac", alg);
250 if (IS_ERR(inst))
251 goto out_put_alg;
252
253 inst->alg.cra_flags = CRYPTO_ALG_TYPE_HASH;
254 inst->alg.cra_priority = alg->cra_priority;
255 inst->alg.cra_blocksize = alg->cra_blocksize;
256 inst->alg.cra_alignmask = alg->cra_alignmask;
257 inst->alg.cra_type = &crypto_hash_type;
258
259 inst->alg.cra_hash.digestsize = ds;
260
261 inst->alg.cra_ctxsize = sizeof(struct hmac_ctx) +
262 ALIGN(inst->alg.cra_blocksize * 2 + ds,
263 sizeof(void *));
264
265 inst->alg.cra_init = hmac_init_tfm;
266 inst->alg.cra_exit = hmac_exit_tfm;
267
268 inst->alg.cra_hash.init = hmac_init;
269 inst->alg.cra_hash.update = hmac_update;
270 inst->alg.cra_hash.final = hmac_final;
271 inst->alg.cra_hash.digest = hmac_digest;
272 inst->alg.cra_hash.setkey = hmac_setkey;
273
274 out_put_alg:
275 crypto_mod_put(alg);
276 return inst;
277 }
278
279 static struct crypto_template hmac_tmpl = {
280 .name = "hmac",
281 .alloc = hmac_alloc,
282 .free = hmac_free,
283 .module = THIS_MODULE,
284 };
285
286 static int __init hmac_module_init(void)
287 {
288 return crypto_register_template(&hmac_tmpl);
289 }
290
291 static void __exit hmac_module_exit(void)
292 {
293 crypto_unregister_template(&hmac_tmpl);
294 }
295
296 module_init(hmac_module_init);
297 module_exit(hmac_module_exit);
298
299 MODULE_LICENSE("GPL");
300 MODULE_DESCRIPTION("HMAC hash algorithm");
301
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