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_shash * parent)141 static int hmac_init_tfm(struct crypto_shash *parent)
142 {
143 struct crypto_shash *hash;
144 struct shash_instance *inst = shash_alg_instance(parent);
145 struct crypto_shash_spawn *spawn = shash_instance_ctx(inst);
146 struct hmac_ctx *ctx = hmac_ctx(parent);
147
148 hash = crypto_spawn_shash(spawn);
149 if (IS_ERR(hash))
150 return PTR_ERR(hash);
151
152 parent->descsize = sizeof(struct shash_desc) +
153 crypto_shash_descsize(hash);
154
155 ctx->hash = hash;
156 return 0;
157 }
158
hmac_exit_tfm(struct crypto_shash * parent)159 static void hmac_exit_tfm(struct crypto_shash *parent)
160 {
161 struct hmac_ctx *ctx = hmac_ctx(parent);
162 crypto_free_shash(ctx->hash);
163 }
164
hmac_create(struct crypto_template * tmpl,struct rtattr ** tb)165 static int hmac_create(struct crypto_template *tmpl, struct rtattr **tb)
166 {
167 struct shash_instance *inst;
168 struct crypto_shash_spawn *spawn;
169 struct crypto_alg *alg;
170 struct shash_alg *salg;
171 u32 mask;
172 int err;
173 int ds;
174 int ss;
175
176 err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_SHASH, &mask);
177 if (err)
178 return err;
179
180 inst = kzalloc(sizeof(*inst) + sizeof(*spawn), GFP_KERNEL);
181 if (!inst)
182 return -ENOMEM;
183 spawn = shash_instance_ctx(inst);
184
185 err = crypto_grab_shash(spawn, shash_crypto_instance(inst),
186 crypto_attr_alg_name(tb[1]), 0, mask);
187 if (err)
188 goto err_free_inst;
189 salg = crypto_spawn_shash_alg(spawn);
190 alg = &salg->base;
191
192 /* The underlying hash algorithm must not require a key */
193 err = -EINVAL;
194 if (crypto_shash_alg_needs_key(salg))
195 goto err_free_inst;
196
197 ds = salg->digestsize;
198 ss = salg->statesize;
199 if (ds > alg->cra_blocksize ||
200 ss < alg->cra_blocksize)
201 goto err_free_inst;
202
203 err = crypto_inst_setname(shash_crypto_instance(inst), tmpl->name, alg);
204 if (err)
205 goto err_free_inst;
206
207 inst->alg.base.cra_priority = alg->cra_priority;
208 inst->alg.base.cra_blocksize = alg->cra_blocksize;
209 inst->alg.base.cra_alignmask = alg->cra_alignmask;
210
211 ss = ALIGN(ss, alg->cra_alignmask + 1);
212 inst->alg.digestsize = ds;
213 inst->alg.statesize = ss;
214
215 inst->alg.base.cra_ctxsize = sizeof(struct hmac_ctx) +
216 ALIGN(ss * 2, crypto_tfm_ctx_alignment());
217
218 inst->alg.init = hmac_init;
219 inst->alg.update = hmac_update;
220 inst->alg.final = hmac_final;
221 inst->alg.finup = hmac_finup;
222 inst->alg.export = hmac_export;
223 inst->alg.import = hmac_import;
224 inst->alg.setkey = hmac_setkey;
225 inst->alg.init_tfm = hmac_init_tfm;
226 inst->alg.exit_tfm = hmac_exit_tfm;
227
228 inst->free = shash_free_singlespawn_instance;
229
230 err = shash_register_instance(tmpl, inst);
231 if (err) {
232 err_free_inst:
233 shash_free_singlespawn_instance(inst);
234 }
235 return err;
236 }
237
238 static struct crypto_template hmac_tmpl = {
239 .name = "hmac",
240 .create = hmac_create,
241 .module = THIS_MODULE,
242 };
243
hmac_module_init(void)244 static int __init hmac_module_init(void)
245 {
246 return crypto_register_template(&hmac_tmpl);
247 }
248
hmac_module_exit(void)249 static void __exit hmac_module_exit(void)
250 {
251 crypto_unregister_template(&hmac_tmpl);
252 }
253
254 subsys_initcall(hmac_module_init);
255 module_exit(hmac_module_exit);
256
257 MODULE_LICENSE("GPL");
258 MODULE_DESCRIPTION("HMAC hash algorithm");
259 MODULE_ALIAS_CRYPTO("hmac");
260