1 // SPDX-License-Identifier: GPL-2.0-or-later
5 * HMAC: Keyed-Hashing for Message Authentication (RFC2104).
7 * Copyright (c) 2002 James Morris <jmorris@intercode.com.au>
8 * Copyright (c) 2006 Herbert Xu <herbert@gondor.apana.org.au>
10 * The HMAC implementation is derived from USAGI.
11 * Copyright (c) 2002 Kazunori Miyazawa <miyazawa@linux-ipv6.org> / USAGI
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>
25 struct crypto_shash *hash;
28 static inline void *align_ptr(void *p, unsigned int align)
30 return (void *)ALIGN((unsigned long)p, align);
33 static inline struct hmac_ctx *hmac_ctx(struct crypto_shash *tfm)
35 return align_ptr(crypto_shash_ctx_aligned(tfm) +
36 crypto_shash_statesize(tfm) * 2,
37 crypto_tfm_ctx_alignment());
40 static int hmac_setkey(struct crypto_shash *parent,
41 const u8 *inkey, unsigned int keylen)
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);
59 err = crypto_shash_digest(shash, inkey, keylen, ipad);
65 memcpy(ipad, inkey, keylen);
67 memset(ipad + keylen, 0, bs - keylen);
68 memcpy(opad, ipad, bs);
70 for (i = 0; i < bs; i++) {
71 ipad[i] ^= HMAC_IPAD_VALUE;
72 opad[i] ^= HMAC_OPAD_VALUE;
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);
83 static int hmac_export(struct shash_desc *pdesc, void *out)
85 struct shash_desc *desc = shash_desc_ctx(pdesc);
87 return crypto_shash_export(desc, out);
90 static int hmac_import(struct shash_desc *pdesc, const void *in)
92 struct shash_desc *desc = shash_desc_ctx(pdesc);
93 struct hmac_ctx *ctx = hmac_ctx(pdesc->tfm);
95 desc->tfm = ctx->hash;
97 return crypto_shash_import(desc, in);
100 static int hmac_init(struct shash_desc *pdesc)
102 return hmac_import(pdesc, crypto_shash_ctx_aligned(pdesc->tfm));
105 static int hmac_update(struct shash_desc *pdesc,
106 const u8 *data, unsigned int nbytes)
108 struct shash_desc *desc = shash_desc_ctx(pdesc);
110 return crypto_shash_update(desc, data, nbytes);
113 static int hmac_final(struct shash_desc *pdesc, u8 *out)
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);
121 return crypto_shash_final(desc, out) ?:
122 crypto_shash_import(desc, opad) ?:
123 crypto_shash_finup(desc, out, ds, out);
126 static int hmac_finup(struct shash_desc *pdesc, const u8 *data,
127 unsigned int nbytes, u8 *out)
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);
136 return crypto_shash_finup(desc, data, nbytes, out) ?:
137 crypto_shash_import(desc, opad) ?:
138 crypto_shash_finup(desc, out, ds, out);
141 static int hmac_init_tfm(struct crypto_shash *parent)
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);
148 hash = crypto_spawn_shash(spawn);
150 return PTR_ERR(hash);
152 parent->descsize = sizeof(struct shash_desc) +
153 crypto_shash_descsize(hash);
159 static void hmac_exit_tfm(struct crypto_shash *parent)
161 struct hmac_ctx *ctx = hmac_ctx(parent);
162 crypto_free_shash(ctx->hash);
165 static int hmac_create(struct crypto_template *tmpl, struct rtattr **tb)
167 struct shash_instance *inst;
168 struct crypto_shash_spawn *spawn;
169 struct crypto_alg *alg;
170 struct shash_alg *salg;
176 err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_SHASH, &mask);
180 inst = kzalloc(sizeof(*inst) + sizeof(*spawn), GFP_KERNEL);
183 spawn = shash_instance_ctx(inst);
185 err = crypto_grab_shash(spawn, shash_crypto_instance(inst),
186 crypto_attr_alg_name(tb[1]), 0, mask);
189 salg = crypto_spawn_shash_alg(spawn);
192 /* The underlying hash algorithm must not require a key */
194 if (crypto_shash_alg_needs_key(salg))
197 ds = salg->digestsize;
198 ss = salg->statesize;
199 if (ds > alg->cra_blocksize ||
200 ss < alg->cra_blocksize)
203 err = crypto_inst_setname(shash_crypto_instance(inst), tmpl->name, alg);
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;
211 ss = ALIGN(ss, alg->cra_alignmask + 1);
212 inst->alg.digestsize = ds;
213 inst->alg.statesize = ss;
215 inst->alg.base.cra_ctxsize = sizeof(struct hmac_ctx) +
216 ALIGN(ss * 2, crypto_tfm_ctx_alignment());
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;
228 inst->free = shash_free_singlespawn_instance;
230 err = shash_register_instance(tmpl, inst);
233 shash_free_singlespawn_instance(inst);
238 static struct crypto_template hmac_tmpl = {
240 .create = hmac_create,
241 .module = THIS_MODULE,
244 static int __init hmac_module_init(void)
246 return crypto_register_template(&hmac_tmpl);
249 static void __exit hmac_module_exit(void)
251 crypto_unregister_template(&hmac_tmpl);
254 subsys_initcall(hmac_module_init);
255 module_exit(hmac_module_exit);
257 MODULE_LICENSE("GPL");
258 MODULE_DESCRIPTION("HMAC hash algorithm");
259 MODULE_ALIAS_CRYPTO("hmac");