1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  * Cryptographic API.
4  *
5  * HMAC: Keyed-Hashing for Message Authentication (RFC2104).
6  *
7  * Copyright (c) 2002 James Morris <jmorris@intercode.com.au>
8  * Copyright (c) 2006 Herbert Xu <herbert@gondor.apana.org.au>
9  *
10  * The HMAC implementation is derived from USAGI.
11  * Copyright (c) 2002 Kazunori Miyazawa <miyazawa@linux-ipv6.org> / USAGI
12  */
13 
14 #include <crypto/hmac.h>
15 #include <crypto/internal/hash.h>
16 #include <crypto/scatterwalk.h>
17 #include <linux/err.h>
18 #include <linux/fips.h>
19 #include <linux/init.h>
20 #include <linux/kernel.h>
21 #include <linux/module.h>
22 #include <linux/scatterlist.h>
23 #include <linux/string.h>
24 
25 struct hmac_ctx {
26 	struct crypto_shash *hash;
27 	/* Contains 'u8 ipad[statesize];', then 'u8 opad[statesize];' */
28 	u8 pads[];
29 };
30 
hmac_setkey(struct crypto_shash * parent,const u8 * inkey,unsigned int keylen)31 static int hmac_setkey(struct crypto_shash *parent,
32 		       const u8 *inkey, unsigned int keylen)
33 {
34 	int bs = crypto_shash_blocksize(parent);
35 	int ds = crypto_shash_digestsize(parent);
36 	int ss = crypto_shash_statesize(parent);
37 	struct hmac_ctx *tctx = crypto_shash_ctx(parent);
38 	struct crypto_shash *hash = tctx->hash;
39 	u8 *ipad = &tctx->pads[0];
40 	u8 *opad = &tctx->pads[ss];
41 	SHASH_DESC_ON_STACK(shash, hash);
42 	unsigned int i;
43 
44 	if (fips_enabled && (keylen < 112 / 8))
45 		return -EINVAL;
46 
47 	shash->tfm = hash;
48 
49 	if (keylen > bs) {
50 		int err;
51 
52 		err = crypto_shash_digest(shash, inkey, keylen, ipad);
53 		if (err)
54 			return err;
55 
56 		keylen = ds;
57 	} else
58 		memcpy(ipad, inkey, keylen);
59 
60 	memset(ipad + keylen, 0, bs - keylen);
61 	memcpy(opad, ipad, bs);
62 
63 	for (i = 0; i < bs; i++) {
64 		ipad[i] ^= HMAC_IPAD_VALUE;
65 		opad[i] ^= HMAC_OPAD_VALUE;
66 	}
67 
68 	return crypto_shash_init(shash) ?:
69 	       crypto_shash_update(shash, ipad, bs) ?:
70 	       crypto_shash_export(shash, ipad) ?:
71 	       crypto_shash_init(shash) ?:
72 	       crypto_shash_update(shash, opad, bs) ?:
73 	       crypto_shash_export(shash, opad);
74 }
75 
hmac_export(struct shash_desc * pdesc,void * out)76 static int hmac_export(struct shash_desc *pdesc, void *out)
77 {
78 	struct shash_desc *desc = shash_desc_ctx(pdesc);
79 
80 	return crypto_shash_export(desc, out);
81 }
82 
hmac_import(struct shash_desc * pdesc,const void * in)83 static int hmac_import(struct shash_desc *pdesc, const void *in)
84 {
85 	struct shash_desc *desc = shash_desc_ctx(pdesc);
86 	const struct hmac_ctx *tctx = crypto_shash_ctx(pdesc->tfm);
87 
88 	desc->tfm = tctx->hash;
89 
90 	return crypto_shash_import(desc, in);
91 }
92 
hmac_init(struct shash_desc * pdesc)93 static int hmac_init(struct shash_desc *pdesc)
94 {
95 	const struct hmac_ctx *tctx = crypto_shash_ctx(pdesc->tfm);
96 
97 	return hmac_import(pdesc, &tctx->pads[0]);
98 }
99 
hmac_update(struct shash_desc * pdesc,const u8 * data,unsigned int nbytes)100 static int hmac_update(struct shash_desc *pdesc,
101 		       const u8 *data, unsigned int nbytes)
102 {
103 	struct shash_desc *desc = shash_desc_ctx(pdesc);
104 
105 	return crypto_shash_update(desc, data, nbytes);
106 }
107 
hmac_final(struct shash_desc * pdesc,u8 * out)108 static int hmac_final(struct shash_desc *pdesc, u8 *out)
109 {
110 	struct crypto_shash *parent = pdesc->tfm;
111 	int ds = crypto_shash_digestsize(parent);
112 	int ss = crypto_shash_statesize(parent);
113 	const struct hmac_ctx *tctx = crypto_shash_ctx(parent);
114 	const u8 *opad = &tctx->pads[ss];
115 	struct shash_desc *desc = shash_desc_ctx(pdesc);
116 
117 	return crypto_shash_final(desc, out) ?:
118 	       crypto_shash_import(desc, opad) ?:
119 	       crypto_shash_finup(desc, out, ds, out);
120 }
121 
hmac_finup(struct shash_desc * pdesc,const u8 * data,unsigned int nbytes,u8 * out)122 static int hmac_finup(struct shash_desc *pdesc, const u8 *data,
123 		      unsigned int nbytes, u8 *out)
124 {
125 
126 	struct crypto_shash *parent = pdesc->tfm;
127 	int ds = crypto_shash_digestsize(parent);
128 	int ss = crypto_shash_statesize(parent);
129 	const struct hmac_ctx *tctx = crypto_shash_ctx(parent);
130 	const u8 *opad = &tctx->pads[ss];
131 	struct shash_desc *desc = shash_desc_ctx(pdesc);
132 
133 	return crypto_shash_finup(desc, data, nbytes, out) ?:
134 	       crypto_shash_import(desc, opad) ?:
135 	       crypto_shash_finup(desc, out, ds, out);
136 }
137 
hmac_init_tfm(struct crypto_shash * parent)138 static int hmac_init_tfm(struct crypto_shash *parent)
139 {
140 	struct crypto_shash *hash;
141 	struct shash_instance *inst = shash_alg_instance(parent);
142 	struct crypto_shash_spawn *spawn = shash_instance_ctx(inst);
143 	struct hmac_ctx *tctx = crypto_shash_ctx(parent);
144 
145 	hash = crypto_spawn_shash(spawn);
146 	if (IS_ERR(hash))
147 		return PTR_ERR(hash);
148 
149 	parent->descsize = sizeof(struct shash_desc) +
150 			   crypto_shash_descsize(hash);
151 
152 	tctx->hash = hash;
153 	return 0;
154 }
155 
hmac_clone_tfm(struct crypto_shash * dst,struct crypto_shash * src)156 static int hmac_clone_tfm(struct crypto_shash *dst, struct crypto_shash *src)
157 {
158 	struct hmac_ctx *sctx = crypto_shash_ctx(src);
159 	struct hmac_ctx *dctx = crypto_shash_ctx(dst);
160 	struct crypto_shash *hash;
161 
162 	hash = crypto_clone_shash(sctx->hash);
163 	if (IS_ERR(hash))
164 		return PTR_ERR(hash);
165 
166 	dctx->hash = hash;
167 	return 0;
168 }
169 
hmac_exit_tfm(struct crypto_shash * parent)170 static void hmac_exit_tfm(struct crypto_shash *parent)
171 {
172 	struct hmac_ctx *tctx = crypto_shash_ctx(parent);
173 
174 	crypto_free_shash(tctx->hash);
175 }
176 
hmac_create(struct crypto_template * tmpl,struct rtattr ** tb)177 static int hmac_create(struct crypto_template *tmpl, struct rtattr **tb)
178 {
179 	struct shash_instance *inst;
180 	struct crypto_shash_spawn *spawn;
181 	struct crypto_alg *alg;
182 	struct shash_alg *salg;
183 	u32 mask;
184 	int err;
185 	int ds;
186 	int ss;
187 
188 	err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_SHASH, &mask);
189 	if (err)
190 		return err;
191 
192 	inst = kzalloc(sizeof(*inst) + sizeof(*spawn), GFP_KERNEL);
193 	if (!inst)
194 		return -ENOMEM;
195 	spawn = shash_instance_ctx(inst);
196 
197 	err = crypto_grab_shash(spawn, shash_crypto_instance(inst),
198 				crypto_attr_alg_name(tb[1]), 0, mask);
199 	if (err)
200 		goto err_free_inst;
201 	salg = crypto_spawn_shash_alg(spawn);
202 	alg = &salg->base;
203 
204 	/* The underlying hash algorithm must not require a key */
205 	err = -EINVAL;
206 	if (crypto_shash_alg_needs_key(salg))
207 		goto err_free_inst;
208 
209 	ds = salg->digestsize;
210 	ss = salg->statesize;
211 	if (ds > alg->cra_blocksize ||
212 	    ss < alg->cra_blocksize)
213 		goto err_free_inst;
214 
215 	err = crypto_inst_setname(shash_crypto_instance(inst), tmpl->name, alg);
216 	if (err)
217 		goto err_free_inst;
218 
219 	inst->alg.base.cra_priority = alg->cra_priority;
220 	inst->alg.base.cra_blocksize = alg->cra_blocksize;
221 	inst->alg.base.cra_ctxsize = sizeof(struct hmac_ctx) + (ss * 2);
222 
223 	inst->alg.digestsize = ds;
224 	inst->alg.statesize = ss;
225 	inst->alg.init = hmac_init;
226 	inst->alg.update = hmac_update;
227 	inst->alg.final = hmac_final;
228 	inst->alg.finup = hmac_finup;
229 	inst->alg.export = hmac_export;
230 	inst->alg.import = hmac_import;
231 	inst->alg.setkey = hmac_setkey;
232 	inst->alg.init_tfm = hmac_init_tfm;
233 	inst->alg.clone_tfm = hmac_clone_tfm;
234 	inst->alg.exit_tfm = hmac_exit_tfm;
235 
236 	inst->free = shash_free_singlespawn_instance;
237 
238 	err = shash_register_instance(tmpl, inst);
239 	if (err) {
240 err_free_inst:
241 		shash_free_singlespawn_instance(inst);
242 	}
243 	return err;
244 }
245 
246 static struct crypto_template hmac_tmpl = {
247 	.name = "hmac",
248 	.create = hmac_create,
249 	.module = THIS_MODULE,
250 };
251 
hmac_module_init(void)252 static int __init hmac_module_init(void)
253 {
254 	return crypto_register_template(&hmac_tmpl);
255 }
256 
hmac_module_exit(void)257 static void __exit hmac_module_exit(void)
258 {
259 	crypto_unregister_template(&hmac_tmpl);
260 }
261 
262 subsys_initcall(hmac_module_init);
263 module_exit(hmac_module_exit);
264 
265 MODULE_LICENSE("GPL");
266 MODULE_DESCRIPTION("HMAC hash algorithm");
267 MODULE_ALIAS_CRYPTO("hmac");
268