xref: /openbmc/linux/crypto/hmac.c (revision 7ed1c1901fe52e6c5828deb155920b44b0adabb1)
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/hmac.h>
20  #include <crypto/internal/hash.h>
21  #include <crypto/scatterwalk.h>
22  #include <linux/err.h>
23  #include <linux/init.h>
24  #include <linux/kernel.h>
25  #include <linux/module.h>
26  #include <linux/scatterlist.h>
27  #include <linux/string.h>
28  
29  struct hmac_ctx {
30  	struct crypto_shash *hash;
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_shash *tfm)
39  {
40  	return align_ptr(crypto_shash_ctx_aligned(tfm) +
41  			 crypto_shash_statesize(tfm) * 2,
42  			 crypto_tfm_ctx_alignment());
43  }
44  
45  static int hmac_setkey(struct crypto_shash *parent,
46  		       const u8 *inkey, unsigned int keylen)
47  {
48  	int bs = crypto_shash_blocksize(parent);
49  	int ds = crypto_shash_digestsize(parent);
50  	int ss = crypto_shash_statesize(parent);
51  	char *ipad = crypto_shash_ctx_aligned(parent);
52  	char *opad = ipad + ss;
53  	struct hmac_ctx *ctx = align_ptr(opad + ss,
54  					 crypto_tfm_ctx_alignment());
55  	struct crypto_shash *hash = ctx->hash;
56  	SHASH_DESC_ON_STACK(shash, hash);
57  	unsigned int i;
58  
59  	shash->tfm = hash;
60  	shash->flags = crypto_shash_get_flags(parent)
61  		& CRYPTO_TFM_REQ_MAY_SLEEP;
62  
63  	if (keylen > bs) {
64  		int err;
65  
66  		err = crypto_shash_digest(shash, inkey, keylen, ipad);
67  		if (err)
68  			return err;
69  
70  		keylen = ds;
71  	} else
72  		memcpy(ipad, inkey, keylen);
73  
74  	memset(ipad + keylen, 0, bs - keylen);
75  	memcpy(opad, ipad, bs);
76  
77  	for (i = 0; i < bs; i++) {
78  		ipad[i] ^= HMAC_IPAD_VALUE;
79  		opad[i] ^= HMAC_OPAD_VALUE;
80  	}
81  
82  	return crypto_shash_init(shash) ?:
83  	       crypto_shash_update(shash, ipad, bs) ?:
84  	       crypto_shash_export(shash, ipad) ?:
85  	       crypto_shash_init(shash) ?:
86  	       crypto_shash_update(shash, opad, bs) ?:
87  	       crypto_shash_export(shash, opad);
88  }
89  
90  static int hmac_export(struct shash_desc *pdesc, void *out)
91  {
92  	struct shash_desc *desc = shash_desc_ctx(pdesc);
93  
94  	desc->flags = pdesc->flags & CRYPTO_TFM_REQ_MAY_SLEEP;
95  
96  	return crypto_shash_export(desc, out);
97  }
98  
99  static int hmac_import(struct shash_desc *pdesc, const void *in)
100  {
101  	struct shash_desc *desc = shash_desc_ctx(pdesc);
102  	struct hmac_ctx *ctx = hmac_ctx(pdesc->tfm);
103  
104  	desc->tfm = ctx->hash;
105  	desc->flags = pdesc->flags & CRYPTO_TFM_REQ_MAY_SLEEP;
106  
107  	return crypto_shash_import(desc, in);
108  }
109  
110  static int hmac_init(struct shash_desc *pdesc)
111  {
112  	return hmac_import(pdesc, crypto_shash_ctx_aligned(pdesc->tfm));
113  }
114  
115  static int hmac_update(struct shash_desc *pdesc,
116  		       const u8 *data, unsigned int nbytes)
117  {
118  	struct shash_desc *desc = shash_desc_ctx(pdesc);
119  
120  	desc->flags = pdesc->flags & CRYPTO_TFM_REQ_MAY_SLEEP;
121  
122  	return crypto_shash_update(desc, data, nbytes);
123  }
124  
125  static int hmac_final(struct shash_desc *pdesc, u8 *out)
126  {
127  	struct crypto_shash *parent = pdesc->tfm;
128  	int ds = crypto_shash_digestsize(parent);
129  	int ss = crypto_shash_statesize(parent);
130  	char *opad = crypto_shash_ctx_aligned(parent) + ss;
131  	struct shash_desc *desc = shash_desc_ctx(pdesc);
132  
133  	desc->flags = pdesc->flags & CRYPTO_TFM_REQ_MAY_SLEEP;
134  
135  	return crypto_shash_final(desc, out) ?:
136  	       crypto_shash_import(desc, opad) ?:
137  	       crypto_shash_finup(desc, out, ds, out);
138  }
139  
140  static int hmac_finup(struct shash_desc *pdesc, const u8 *data,
141  		      unsigned int nbytes, u8 *out)
142  {
143  
144  	struct crypto_shash *parent = pdesc->tfm;
145  	int ds = crypto_shash_digestsize(parent);
146  	int ss = crypto_shash_statesize(parent);
147  	char *opad = crypto_shash_ctx_aligned(parent) + ss;
148  	struct shash_desc *desc = shash_desc_ctx(pdesc);
149  
150  	desc->flags = pdesc->flags & CRYPTO_TFM_REQ_MAY_SLEEP;
151  
152  	return crypto_shash_finup(desc, data, nbytes, out) ?:
153  	       crypto_shash_import(desc, opad) ?:
154  	       crypto_shash_finup(desc, out, ds, out);
155  }
156  
157  static int hmac_init_tfm(struct crypto_tfm *tfm)
158  {
159  	struct crypto_shash *parent = __crypto_shash_cast(tfm);
160  	struct crypto_shash *hash;
161  	struct crypto_instance *inst = (void *)tfm->__crt_alg;
162  	struct crypto_shash_spawn *spawn = crypto_instance_ctx(inst);
163  	struct hmac_ctx *ctx = hmac_ctx(parent);
164  
165  	hash = crypto_spawn_shash(spawn);
166  	if (IS_ERR(hash))
167  		return PTR_ERR(hash);
168  
169  	parent->descsize = sizeof(struct shash_desc) +
170  			   crypto_shash_descsize(hash);
171  
172  	ctx->hash = hash;
173  	return 0;
174  }
175  
176  static void hmac_exit_tfm(struct crypto_tfm *tfm)
177  {
178  	struct hmac_ctx *ctx = hmac_ctx(__crypto_shash_cast(tfm));
179  	crypto_free_shash(ctx->hash);
180  }
181  
182  static int hmac_create(struct crypto_template *tmpl, struct rtattr **tb)
183  {
184  	struct shash_instance *inst;
185  	struct crypto_alg *alg;
186  	struct shash_alg *salg;
187  	int err;
188  	int ds;
189  	int ss;
190  
191  	err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_SHASH);
192  	if (err)
193  		return err;
194  
195  	salg = shash_attr_alg(tb[1], 0, 0);
196  	if (IS_ERR(salg))
197  		return PTR_ERR(salg);
198  	alg = &salg->base;
199  
200  	/* The underlying hash algorithm must be unkeyed */
201  	err = -EINVAL;
202  	if (crypto_shash_alg_has_setkey(salg))
203  		goto out_put_alg;
204  
205  	ds = salg->digestsize;
206  	ss = salg->statesize;
207  	if (ds > alg->cra_blocksize ||
208  	    ss < alg->cra_blocksize)
209  		goto out_put_alg;
210  
211  	inst = shash_alloc_instance("hmac", alg);
212  	err = PTR_ERR(inst);
213  	if (IS_ERR(inst))
214  		goto out_put_alg;
215  
216  	err = crypto_init_shash_spawn(shash_instance_ctx(inst), salg,
217  				      shash_crypto_instance(inst));
218  	if (err)
219  		goto out_free_inst;
220  
221  	inst->alg.base.cra_priority = alg->cra_priority;
222  	inst->alg.base.cra_blocksize = alg->cra_blocksize;
223  	inst->alg.base.cra_alignmask = alg->cra_alignmask;
224  
225  	ss = ALIGN(ss, alg->cra_alignmask + 1);
226  	inst->alg.digestsize = ds;
227  	inst->alg.statesize = ss;
228  
229  	inst->alg.base.cra_ctxsize = sizeof(struct hmac_ctx) +
230  				     ALIGN(ss * 2, crypto_tfm_ctx_alignment());
231  
232  	inst->alg.base.cra_init = hmac_init_tfm;
233  	inst->alg.base.cra_exit = hmac_exit_tfm;
234  
235  	inst->alg.init = hmac_init;
236  	inst->alg.update = hmac_update;
237  	inst->alg.final = hmac_final;
238  	inst->alg.finup = hmac_finup;
239  	inst->alg.export = hmac_export;
240  	inst->alg.import = hmac_import;
241  	inst->alg.setkey = hmac_setkey;
242  
243  	err = shash_register_instance(tmpl, inst);
244  	if (err) {
245  out_free_inst:
246  		shash_free_instance(shash_crypto_instance(inst));
247  	}
248  
249  out_put_alg:
250  	crypto_mod_put(alg);
251  	return err;
252  }
253  
254  static struct crypto_template hmac_tmpl = {
255  	.name = "hmac",
256  	.create = hmac_create,
257  	.free = shash_free_instance,
258  	.module = THIS_MODULE,
259  };
260  
261  static int __init hmac_module_init(void)
262  {
263  	return crypto_register_template(&hmac_tmpl);
264  }
265  
266  static void __exit hmac_module_exit(void)
267  {
268  	crypto_unregister_template(&hmac_tmpl);
269  }
270  
271  module_init(hmac_module_init);
272  module_exit(hmac_module_exit);
273  
274  MODULE_LICENSE("GPL");
275  MODULE_DESCRIPTION("HMAC hash algorithm");
276  MODULE_ALIAS_CRYPTO("hmac");
277