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 };
28
align_ptr(void * p,unsigned int align)29 static inline void *align_ptr(void *p, unsigned int align)
30 {
31 return (void *)ALIGN((unsigned long)p, align);
32 }
33
hmac_ctx(struct crypto_shash * tfm)34 static inline struct hmac_ctx *hmac_ctx(struct crypto_shash *tfm)
35 {
36 return align_ptr(crypto_shash_ctx_aligned(tfm) +
37 crypto_shash_statesize(tfm) * 2,
38 crypto_tfm_ctx_alignment());
39 }
40
hmac_setkey(struct crypto_shash * parent,const u8 * inkey,unsigned int keylen)41 static int hmac_setkey(struct crypto_shash *parent,
42 const u8 *inkey, unsigned int keylen)
43 {
44 int bs = crypto_shash_blocksize(parent);
45 int ds = crypto_shash_digestsize(parent);
46 int ss = crypto_shash_statesize(parent);
47 char *ipad = crypto_shash_ctx_aligned(parent);
48 char *opad = ipad + ss;
49 struct hmac_ctx *ctx = align_ptr(opad + ss,
50 crypto_tfm_ctx_alignment());
51 struct crypto_shash *hash = ctx->hash;
52 SHASH_DESC_ON_STACK(shash, hash);
53 unsigned int i;
54
55 if (fips_enabled && (keylen < 112 / 8))
56 return -EINVAL;
57
58 shash->tfm = hash;
59
60 if (keylen > bs) {
61 int err;
62
63 err = crypto_shash_digest(shash, inkey, keylen, ipad);
64 if (err)
65 return err;
66
67 keylen = ds;
68 } else
69 memcpy(ipad, inkey, keylen);
70
71 memset(ipad + keylen, 0, bs - keylen);
72 memcpy(opad, ipad, bs);
73
74 for (i = 0; i < bs; i++) {
75 ipad[i] ^= HMAC_IPAD_VALUE;
76 opad[i] ^= HMAC_OPAD_VALUE;
77 }
78
79 return crypto_shash_init(shash) ?:
80 crypto_shash_update(shash, ipad, bs) ?:
81 crypto_shash_export(shash, ipad) ?:
82 crypto_shash_init(shash) ?:
83 crypto_shash_update(shash, opad, bs) ?:
84 crypto_shash_export(shash, opad);
85 }
86
hmac_export(struct shash_desc * pdesc,void * out)87 static int hmac_export(struct shash_desc *pdesc, void *out)
88 {
89 struct shash_desc *desc = shash_desc_ctx(pdesc);
90
91 return crypto_shash_export(desc, out);
92 }
93
hmac_import(struct shash_desc * pdesc,const void * in)94 static int hmac_import(struct shash_desc *pdesc, const void *in)
95 {
96 struct shash_desc *desc = shash_desc_ctx(pdesc);
97 struct hmac_ctx *ctx = hmac_ctx(pdesc->tfm);
98
99 desc->tfm = ctx->hash;
100
101 return crypto_shash_import(desc, in);
102 }
103
hmac_init(struct shash_desc * pdesc)104 static int hmac_init(struct shash_desc *pdesc)
105 {
106 return hmac_import(pdesc, crypto_shash_ctx_aligned(pdesc->tfm));
107 }
108
hmac_update(struct shash_desc * pdesc,const u8 * data,unsigned int nbytes)109 static int hmac_update(struct shash_desc *pdesc,
110 const u8 *data, unsigned int nbytes)
111 {
112 struct shash_desc *desc = shash_desc_ctx(pdesc);
113
114 return crypto_shash_update(desc, data, nbytes);
115 }
116
hmac_final(struct shash_desc * pdesc,u8 * out)117 static int hmac_final(struct shash_desc *pdesc, u8 *out)
118 {
119 struct crypto_shash *parent = pdesc->tfm;
120 int ds = crypto_shash_digestsize(parent);
121 int ss = crypto_shash_statesize(parent);
122 char *opad = crypto_shash_ctx_aligned(parent) + ss;
123 struct shash_desc *desc = shash_desc_ctx(pdesc);
124
125 return crypto_shash_final(desc, out) ?:
126 crypto_shash_import(desc, opad) ?:
127 crypto_shash_finup(desc, out, ds, out);
128 }
129
hmac_finup(struct shash_desc * pdesc,const u8 * data,unsigned int nbytes,u8 * out)130 static int hmac_finup(struct shash_desc *pdesc, const u8 *data,
131 unsigned int nbytes, u8 *out)
132 {
133
134 struct crypto_shash *parent = pdesc->tfm;
135 int ds = crypto_shash_digestsize(parent);
136 int ss = crypto_shash_statesize(parent);
137 char *opad = crypto_shash_ctx_aligned(parent) + ss;
138 struct shash_desc *desc = shash_desc_ctx(pdesc);
139
140 return crypto_shash_finup(desc, data, nbytes, out) ?:
141 crypto_shash_import(desc, opad) ?:
142 crypto_shash_finup(desc, out, ds, out);
143 }
144
hmac_init_tfm(struct crypto_shash * parent)145 static int hmac_init_tfm(struct crypto_shash *parent)
146 {
147 struct crypto_shash *hash;
148 struct shash_instance *inst = shash_alg_instance(parent);
149 struct crypto_shash_spawn *spawn = shash_instance_ctx(inst);
150 struct hmac_ctx *ctx = hmac_ctx(parent);
151
152 hash = crypto_spawn_shash(spawn);
153 if (IS_ERR(hash))
154 return PTR_ERR(hash);
155
156 parent->descsize = sizeof(struct shash_desc) +
157 crypto_shash_descsize(hash);
158
159 ctx->hash = hash;
160 return 0;
161 }
162
hmac_clone_tfm(struct crypto_shash * dst,struct crypto_shash * src)163 static int hmac_clone_tfm(struct crypto_shash *dst, struct crypto_shash *src)
164 {
165 struct hmac_ctx *sctx = hmac_ctx(src);
166 struct hmac_ctx *dctx = hmac_ctx(dst);
167 struct crypto_shash *hash;
168
169 hash = crypto_clone_shash(sctx->hash);
170 if (IS_ERR(hash))
171 return PTR_ERR(hash);
172
173 dctx->hash = hash;
174 return 0;
175 }
176
hmac_exit_tfm(struct crypto_shash * parent)177 static void hmac_exit_tfm(struct crypto_shash *parent)
178 {
179 struct hmac_ctx *ctx = hmac_ctx(parent);
180
181 crypto_free_shash(ctx->hash);
182 }
183
hmac_create(struct crypto_template * tmpl,struct rtattr ** tb)184 static int hmac_create(struct crypto_template *tmpl, struct rtattr **tb)
185 {
186 struct shash_instance *inst;
187 struct crypto_shash_spawn *spawn;
188 struct crypto_alg *alg;
189 struct shash_alg *salg;
190 u32 mask;
191 int err;
192 int ds;
193 int ss;
194
195 err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_SHASH, &mask);
196 if (err)
197 return err;
198
199 inst = kzalloc(sizeof(*inst) + sizeof(*spawn), GFP_KERNEL);
200 if (!inst)
201 return -ENOMEM;
202 spawn = shash_instance_ctx(inst);
203
204 err = crypto_grab_shash(spawn, shash_crypto_instance(inst),
205 crypto_attr_alg_name(tb[1]), 0, mask);
206 if (err)
207 goto err_free_inst;
208 salg = crypto_spawn_shash_alg(spawn);
209 alg = &salg->base;
210
211 /* The underlying hash algorithm must not require a key */
212 err = -EINVAL;
213 if (crypto_shash_alg_needs_key(salg))
214 goto err_free_inst;
215
216 ds = salg->digestsize;
217 ss = salg->statesize;
218 if (ds > alg->cra_blocksize ||
219 ss < alg->cra_blocksize)
220 goto err_free_inst;
221
222 err = crypto_inst_setname(shash_crypto_instance(inst), tmpl->name, alg);
223 if (err)
224 goto err_free_inst;
225
226 inst->alg.base.cra_priority = alg->cra_priority;
227 inst->alg.base.cra_blocksize = alg->cra_blocksize;
228 inst->alg.base.cra_alignmask = alg->cra_alignmask;
229
230 ss = ALIGN(ss, alg->cra_alignmask + 1);
231 inst->alg.digestsize = ds;
232 inst->alg.statesize = ss;
233
234 inst->alg.base.cra_ctxsize = sizeof(struct hmac_ctx) +
235 ALIGN(ss * 2, crypto_tfm_ctx_alignment());
236
237 inst->alg.init = hmac_init;
238 inst->alg.update = hmac_update;
239 inst->alg.final = hmac_final;
240 inst->alg.finup = hmac_finup;
241 inst->alg.export = hmac_export;
242 inst->alg.import = hmac_import;
243 inst->alg.setkey = hmac_setkey;
244 inst->alg.init_tfm = hmac_init_tfm;
245 inst->alg.clone_tfm = hmac_clone_tfm;
246 inst->alg.exit_tfm = hmac_exit_tfm;
247
248 inst->free = shash_free_singlespawn_instance;
249
250 err = shash_register_instance(tmpl, inst);
251 if (err) {
252 err_free_inst:
253 shash_free_singlespawn_instance(inst);
254 }
255 return err;
256 }
257
258 static struct crypto_template hmac_tmpl = {
259 .name = "hmac",
260 .create = hmac_create,
261 .module = THIS_MODULE,
262 };
263
hmac_module_init(void)264 static int __init hmac_module_init(void)
265 {
266 return crypto_register_template(&hmac_tmpl);
267 }
268
hmac_module_exit(void)269 static void __exit hmac_module_exit(void)
270 {
271 crypto_unregister_template(&hmac_tmpl);
272 }
273
274 subsys_initcall(hmac_module_init);
275 module_exit(hmac_module_exit);
276
277 MODULE_LICENSE("GPL");
278 MODULE_DESCRIPTION("HMAC hash algorithm");
279 MODULE_ALIAS_CRYPTO("hmac");
280
