xref: /openbmc/linux/crypto/hmac.c (revision f75bd28b)
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