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/init.h>
19 #include <linux/kernel.h>
20 #include <linux/module.h>
21 #include <linux/scatterlist.h>
22 #include <linux/string.h>
23
24 struct hmac_ctx {
25 struct crypto_shash *hash;
26 };
27
align_ptr(void * p,unsigned int align)28 static inline void *align_ptr(void *p, unsigned int align)
29 {
30 return (void *)ALIGN((unsigned long)p, align);
31 }
32
hmac_ctx(struct crypto_shash * tfm)33 static inline struct hmac_ctx *hmac_ctx(struct crypto_shash *tfm)
34 {
35 return align_ptr(crypto_shash_ctx_aligned(tfm) +
36 crypto_shash_statesize(tfm) * 2,
37 crypto_tfm_ctx_alignment());
38 }
39
hmac_setkey(struct crypto_shash * parent,const u8 * inkey,unsigned int keylen)40 static int hmac_setkey(struct crypto_shash *parent,
41 const u8 *inkey, unsigned int keylen)
42 {
43 int bs = crypto_shash_blocksize(parent);
44 int ds = crypto_shash_digestsize(parent);
45 int ss = crypto_shash_statesize(parent);
46 char *ipad = crypto_shash_ctx_aligned(parent);
47 char *opad = ipad + ss;
48 struct hmac_ctx *ctx = align_ptr(opad + ss,
49 crypto_tfm_ctx_alignment());
50 struct crypto_shash *hash = ctx->hash;
51 SHASH_DESC_ON_STACK(shash, hash);
52 unsigned int i;
53
54 shash->tfm = hash;
55
56 if (keylen > bs) {
57 int err;
58
59 err = crypto_shash_digest(shash, inkey, keylen, ipad);
60 if (err)
61 return err;
62
63 keylen = ds;
64 } else
65 memcpy(ipad, inkey, keylen);
66
67 memset(ipad + keylen, 0, bs - keylen);
68 memcpy(opad, ipad, bs);
69
70 for (i = 0; i < bs; i++) {
71 ipad[i] ^= HMAC_IPAD_VALUE;
72 opad[i] ^= HMAC_OPAD_VALUE;
73 }
74
75 return crypto_shash_init(shash) ?:
76 crypto_shash_update(shash, ipad, bs) ?:
77 crypto_shash_export(shash, ipad) ?:
78 crypto_shash_init(shash) ?:
79 crypto_shash_update(shash, opad, bs) ?:
80 crypto_shash_export(shash, opad);
81 }
82
hmac_export(struct shash_desc * pdesc,void * out)83 static int hmac_export(struct shash_desc *pdesc, void *out)
84 {
85 struct shash_desc *desc = shash_desc_ctx(pdesc);
86
87 return crypto_shash_export(desc, out);
88 }
89
hmac_import(struct shash_desc * pdesc,const void * in)90 static int hmac_import(struct shash_desc *pdesc, const void *in)
91 {
92 struct shash_desc *desc = shash_desc_ctx(pdesc);
93 struct hmac_ctx *ctx = hmac_ctx(pdesc->tfm);
94
95 desc->tfm = ctx->hash;
96
97 return crypto_shash_import(desc, in);
98 }
99
hmac_init(struct shash_desc * pdesc)100 static int hmac_init(struct shash_desc *pdesc)
101 {
102 return hmac_import(pdesc, crypto_shash_ctx_aligned(pdesc->tfm));
103 }
104
hmac_update(struct shash_desc * pdesc,const u8 * data,unsigned int nbytes)105 static int hmac_update(struct shash_desc *pdesc,
106 const u8 *data, unsigned int nbytes)
107 {
108 struct shash_desc *desc = shash_desc_ctx(pdesc);
109
110 return crypto_shash_update(desc, data, nbytes);
111 }
112
hmac_final(struct shash_desc * pdesc,u8 * out)113 static int hmac_final(struct shash_desc *pdesc, u8 *out)
114 {
115 struct crypto_shash *parent = pdesc->tfm;
116 int ds = crypto_shash_digestsize(parent);
117 int ss = crypto_shash_statesize(parent);
118 char *opad = crypto_shash_ctx_aligned(parent) + ss;
119 struct shash_desc *desc = shash_desc_ctx(pdesc);
120
121 return crypto_shash_final(desc, out) ?:
122 crypto_shash_import(desc, opad) ?:
123 crypto_shash_finup(desc, out, ds, out);
124 }
125
hmac_finup(struct shash_desc * pdesc,const u8 * data,unsigned int nbytes,u8 * out)126 static int hmac_finup(struct shash_desc *pdesc, const u8 *data,
127 unsigned int nbytes, u8 *out)
128 {
129
130 struct crypto_shash *parent = pdesc->tfm;
131 int ds = crypto_shash_digestsize(parent);
132 int ss = crypto_shash_statesize(parent);
133 char *opad = crypto_shash_ctx_aligned(parent) + ss;
134 struct shash_desc *desc = shash_desc_ctx(pdesc);
135
136 return crypto_shash_finup(desc, data, nbytes, out) ?:
137 crypto_shash_import(desc, opad) ?:
138 crypto_shash_finup(desc, out, ds, out);
139 }
140
hmac_init_tfm(struct crypto_tfm * tfm)141 static int hmac_init_tfm(struct crypto_tfm *tfm)
142 {
143 struct crypto_shash *parent = __crypto_shash_cast(tfm);
144 struct crypto_shash *hash;
145 struct crypto_instance *inst = (void *)tfm->__crt_alg;
146 struct crypto_shash_spawn *spawn = crypto_instance_ctx(inst);
147 struct hmac_ctx *ctx = hmac_ctx(parent);
148
149 hash = crypto_spawn_shash(spawn);
150 if (IS_ERR(hash))
151 return PTR_ERR(hash);
152
153 parent->descsize = sizeof(struct shash_desc) +
154 crypto_shash_descsize(hash);
155 if (WARN_ON(parent->descsize > HASH_MAX_DESCSIZE)) {
156 crypto_free_shash(hash);
157 return -EINVAL;
158 }
159
160 ctx->hash = hash;
161 return 0;
162 }
163
hmac_exit_tfm(struct crypto_tfm * tfm)164 static void hmac_exit_tfm(struct crypto_tfm *tfm)
165 {
166 struct hmac_ctx *ctx = hmac_ctx(__crypto_shash_cast(tfm));
167 crypto_free_shash(ctx->hash);
168 }
169
hmac_create(struct crypto_template * tmpl,struct rtattr ** tb)170 static int hmac_create(struct crypto_template *tmpl, struct rtattr **tb)
171 {
172 struct shash_instance *inst;
173 struct crypto_alg *alg;
174 struct shash_alg *salg;
175 int err;
176 int ds;
177 int ss;
178
179 err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_SHASH);
180 if (err)
181 return err;
182
183 salg = shash_attr_alg(tb[1], 0, 0);
184 if (IS_ERR(salg))
185 return PTR_ERR(salg);
186 alg = &salg->base;
187
188 /* The underlying hash algorithm must be unkeyed */
189 err = -EINVAL;
190 if (crypto_shash_alg_has_setkey(salg))
191 goto out_put_alg;
192
193 ds = salg->digestsize;
194 ss = salg->statesize;
195 if (ds > alg->cra_blocksize ||
196 ss < alg->cra_blocksize)
197 goto out_put_alg;
198
199 inst = shash_alloc_instance("hmac", alg);
200 err = PTR_ERR(inst);
201 if (IS_ERR(inst))
202 goto out_put_alg;
203
204 err = crypto_init_shash_spawn(shash_instance_ctx(inst), salg,
205 shash_crypto_instance(inst));
206 if (err)
207 goto out_free_inst;
208
209 inst->alg.base.cra_priority = alg->cra_priority;
210 inst->alg.base.cra_blocksize = alg->cra_blocksize;
211 inst->alg.base.cra_alignmask = alg->cra_alignmask;
212
213 ss = ALIGN(ss, alg->cra_alignmask + 1);
214 inst->alg.digestsize = ds;
215 inst->alg.statesize = ss;
216
217 inst->alg.base.cra_ctxsize = sizeof(struct hmac_ctx) +
218 ALIGN(ss * 2, crypto_tfm_ctx_alignment());
219
220 inst->alg.base.cra_init = hmac_init_tfm;
221 inst->alg.base.cra_exit = hmac_exit_tfm;
222
223 inst->alg.init = hmac_init;
224 inst->alg.update = hmac_update;
225 inst->alg.final = hmac_final;
226 inst->alg.finup = hmac_finup;
227 inst->alg.export = hmac_export;
228 inst->alg.import = hmac_import;
229 inst->alg.setkey = hmac_setkey;
230
231 err = shash_register_instance(tmpl, inst);
232 if (err) {
233 out_free_inst:
234 shash_free_instance(shash_crypto_instance(inst));
235 }
236
237 out_put_alg:
238 crypto_mod_put(alg);
239 return err;
240 }
241
242 static struct crypto_template hmac_tmpl = {
243 .name = "hmac",
244 .create = hmac_create,
245 .free = shash_free_instance,
246 .module = THIS_MODULE,
247 };
248
hmac_module_init(void)249 static int __init hmac_module_init(void)
250 {
251 return crypto_register_template(&hmac_tmpl);
252 }
253
hmac_module_exit(void)254 static void __exit hmac_module_exit(void)
255 {
256 crypto_unregister_template(&hmac_tmpl);
257 }
258
259 subsys_initcall(hmac_module_init);
260 module_exit(hmac_module_exit);
261
262 MODULE_LICENSE("GPL");
263 MODULE_DESCRIPTION("HMAC hash algorithm");
264 MODULE_ALIAS_CRYPTO("hmac");
265