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Linux/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/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");
272 

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