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
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
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
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
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
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
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
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
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
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
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
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
252 static int __init hmac_module_init(void)
253 {
254 return crypto_register_template(&hmac_tmpl);
255 }
256
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
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