xref: /openbmc/linux/crypto/hmac.c (revision fa7f32422ea1ac276b45b96a540ed5981caaa61f)
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