xref: /openbmc/linux/crypto/skcipher.c (revision eb3fcf00)
1 /*
2  * Symmetric key cipher operations.
3  *
4  * Generic encrypt/decrypt wrapper for ciphers, handles operations across
5  * multiple page boundaries by using temporary blocks.  In user context,
6  * the kernel is given a chance to schedule us once per page.
7  *
8  * Copyright (c) 2015 Herbert Xu <herbert@gondor.apana.org.au>
9  *
10  * This program is free software; you can redistribute it and/or modify it
11  * under the terms of the GNU General Public License as published by the Free
12  * Software Foundation; either version 2 of the License, or (at your option)
13  * any later version.
14  *
15  */
16 
17 #include <crypto/internal/skcipher.h>
18 #include <linux/bug.h>
19 #include <linux/module.h>
20 
21 #include "internal.h"
22 
23 static unsigned int crypto_skcipher_extsize(struct crypto_alg *alg)
24 {
25 	if (alg->cra_type == &crypto_blkcipher_type)
26 		return sizeof(struct crypto_blkcipher *);
27 
28 	BUG_ON(alg->cra_type != &crypto_ablkcipher_type &&
29 	       alg->cra_type != &crypto_givcipher_type);
30 
31 	return sizeof(struct crypto_ablkcipher *);
32 }
33 
34 static int skcipher_setkey_blkcipher(struct crypto_skcipher *tfm,
35 				     const u8 *key, unsigned int keylen)
36 {
37 	struct crypto_blkcipher **ctx = crypto_skcipher_ctx(tfm);
38 	struct crypto_blkcipher *blkcipher = *ctx;
39 	int err;
40 
41 	crypto_blkcipher_clear_flags(blkcipher, ~0);
42 	crypto_blkcipher_set_flags(blkcipher, crypto_skcipher_get_flags(tfm) &
43 					      CRYPTO_TFM_REQ_MASK);
44 	err = crypto_blkcipher_setkey(blkcipher, key, keylen);
45 	crypto_skcipher_set_flags(tfm, crypto_blkcipher_get_flags(blkcipher) &
46 				       CRYPTO_TFM_RES_MASK);
47 
48 	return err;
49 }
50 
51 static int skcipher_crypt_blkcipher(struct skcipher_request *req,
52 				    int (*crypt)(struct blkcipher_desc *,
53 						 struct scatterlist *,
54 						 struct scatterlist *,
55 						 unsigned int))
56 {
57 	struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
58 	struct crypto_blkcipher **ctx = crypto_skcipher_ctx(tfm);
59 	struct blkcipher_desc desc = {
60 		.tfm = *ctx,
61 		.info = req->iv,
62 		.flags = req->base.flags,
63 	};
64 
65 
66 	return crypt(&desc, req->dst, req->src, req->cryptlen);
67 }
68 
69 static int skcipher_encrypt_blkcipher(struct skcipher_request *req)
70 {
71 	struct crypto_skcipher *skcipher = crypto_skcipher_reqtfm(req);
72 	struct crypto_tfm *tfm = crypto_skcipher_tfm(skcipher);
73 	struct blkcipher_alg *alg = &tfm->__crt_alg->cra_blkcipher;
74 
75 	return skcipher_crypt_blkcipher(req, alg->encrypt);
76 }
77 
78 static int skcipher_decrypt_blkcipher(struct skcipher_request *req)
79 {
80 	struct crypto_skcipher *skcipher = crypto_skcipher_reqtfm(req);
81 	struct crypto_tfm *tfm = crypto_skcipher_tfm(skcipher);
82 	struct blkcipher_alg *alg = &tfm->__crt_alg->cra_blkcipher;
83 
84 	return skcipher_crypt_blkcipher(req, alg->decrypt);
85 }
86 
87 static void crypto_exit_skcipher_ops_blkcipher(struct crypto_tfm *tfm)
88 {
89 	struct crypto_blkcipher **ctx = crypto_tfm_ctx(tfm);
90 
91 	crypto_free_blkcipher(*ctx);
92 }
93 
94 int crypto_init_skcipher_ops_blkcipher(struct crypto_tfm *tfm)
95 {
96 	struct crypto_alg *calg = tfm->__crt_alg;
97 	struct crypto_skcipher *skcipher = __crypto_skcipher_cast(tfm);
98 	struct crypto_blkcipher **ctx = crypto_tfm_ctx(tfm);
99 	struct crypto_blkcipher *blkcipher;
100 	struct crypto_tfm *btfm;
101 
102 	if (!crypto_mod_get(calg))
103 		return -EAGAIN;
104 
105 	btfm = __crypto_alloc_tfm(calg, CRYPTO_ALG_TYPE_BLKCIPHER,
106 					CRYPTO_ALG_TYPE_MASK);
107 	if (IS_ERR(btfm)) {
108 		crypto_mod_put(calg);
109 		return PTR_ERR(btfm);
110 	}
111 
112 	blkcipher = __crypto_blkcipher_cast(btfm);
113 	*ctx = blkcipher;
114 	tfm->exit = crypto_exit_skcipher_ops_blkcipher;
115 
116 	skcipher->setkey = skcipher_setkey_blkcipher;
117 	skcipher->encrypt = skcipher_encrypt_blkcipher;
118 	skcipher->decrypt = skcipher_decrypt_blkcipher;
119 
120 	skcipher->ivsize = crypto_blkcipher_ivsize(blkcipher);
121 
122 	return 0;
123 }
124 
125 static int skcipher_setkey_ablkcipher(struct crypto_skcipher *tfm,
126 				      const u8 *key, unsigned int keylen)
127 {
128 	struct crypto_ablkcipher **ctx = crypto_skcipher_ctx(tfm);
129 	struct crypto_ablkcipher *ablkcipher = *ctx;
130 	int err;
131 
132 	crypto_ablkcipher_clear_flags(ablkcipher, ~0);
133 	crypto_ablkcipher_set_flags(ablkcipher,
134 				    crypto_skcipher_get_flags(tfm) &
135 				    CRYPTO_TFM_REQ_MASK);
136 	err = crypto_ablkcipher_setkey(ablkcipher, key, keylen);
137 	crypto_skcipher_set_flags(tfm,
138 				  crypto_ablkcipher_get_flags(ablkcipher) &
139 				  CRYPTO_TFM_RES_MASK);
140 
141 	return err;
142 }
143 
144 static int skcipher_crypt_ablkcipher(struct skcipher_request *req,
145 				     int (*crypt)(struct ablkcipher_request *))
146 {
147 	struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
148 	struct crypto_ablkcipher **ctx = crypto_skcipher_ctx(tfm);
149 	struct ablkcipher_request *subreq = skcipher_request_ctx(req);
150 
151 	ablkcipher_request_set_tfm(subreq, *ctx);
152 	ablkcipher_request_set_callback(subreq, skcipher_request_flags(req),
153 					req->base.complete, req->base.data);
154 	ablkcipher_request_set_crypt(subreq, req->src, req->dst, req->cryptlen,
155 				     req->iv);
156 
157 	return crypt(subreq);
158 }
159 
160 static int skcipher_encrypt_ablkcipher(struct skcipher_request *req)
161 {
162 	struct crypto_skcipher *skcipher = crypto_skcipher_reqtfm(req);
163 	struct crypto_tfm *tfm = crypto_skcipher_tfm(skcipher);
164 	struct ablkcipher_alg *alg = &tfm->__crt_alg->cra_ablkcipher;
165 
166 	return skcipher_crypt_ablkcipher(req, alg->encrypt);
167 }
168 
169 static int skcipher_decrypt_ablkcipher(struct skcipher_request *req)
170 {
171 	struct crypto_skcipher *skcipher = crypto_skcipher_reqtfm(req);
172 	struct crypto_tfm *tfm = crypto_skcipher_tfm(skcipher);
173 	struct ablkcipher_alg *alg = &tfm->__crt_alg->cra_ablkcipher;
174 
175 	return skcipher_crypt_ablkcipher(req, alg->decrypt);
176 }
177 
178 static void crypto_exit_skcipher_ops_ablkcipher(struct crypto_tfm *tfm)
179 {
180 	struct crypto_ablkcipher **ctx = crypto_tfm_ctx(tfm);
181 
182 	crypto_free_ablkcipher(*ctx);
183 }
184 
185 int crypto_init_skcipher_ops_ablkcipher(struct crypto_tfm *tfm)
186 {
187 	struct crypto_alg *calg = tfm->__crt_alg;
188 	struct crypto_skcipher *skcipher = __crypto_skcipher_cast(tfm);
189 	struct crypto_ablkcipher **ctx = crypto_tfm_ctx(tfm);
190 	struct crypto_ablkcipher *ablkcipher;
191 	struct crypto_tfm *abtfm;
192 
193 	if (!crypto_mod_get(calg))
194 		return -EAGAIN;
195 
196 	abtfm = __crypto_alloc_tfm(calg, 0, 0);
197 	if (IS_ERR(abtfm)) {
198 		crypto_mod_put(calg);
199 		return PTR_ERR(abtfm);
200 	}
201 
202 	ablkcipher = __crypto_ablkcipher_cast(abtfm);
203 	*ctx = ablkcipher;
204 	tfm->exit = crypto_exit_skcipher_ops_ablkcipher;
205 
206 	skcipher->setkey = skcipher_setkey_ablkcipher;
207 	skcipher->encrypt = skcipher_encrypt_ablkcipher;
208 	skcipher->decrypt = skcipher_decrypt_ablkcipher;
209 
210 	skcipher->ivsize = crypto_ablkcipher_ivsize(ablkcipher);
211 	skcipher->reqsize = crypto_ablkcipher_reqsize(ablkcipher) +
212 			    sizeof(struct ablkcipher_request);
213 
214 	return 0;
215 }
216 
217 static int crypto_skcipher_init_tfm(struct crypto_tfm *tfm)
218 {
219 	if (tfm->__crt_alg->cra_type == &crypto_blkcipher_type)
220 		return crypto_init_skcipher_ops_blkcipher(tfm);
221 
222 	BUG_ON(tfm->__crt_alg->cra_type != &crypto_ablkcipher_type &&
223 	       tfm->__crt_alg->cra_type != &crypto_givcipher_type);
224 
225 	return crypto_init_skcipher_ops_ablkcipher(tfm);
226 }
227 
228 static const struct crypto_type crypto_skcipher_type2 = {
229 	.extsize = crypto_skcipher_extsize,
230 	.init_tfm = crypto_skcipher_init_tfm,
231 	.maskclear = ~CRYPTO_ALG_TYPE_MASK,
232 	.maskset = CRYPTO_ALG_TYPE_BLKCIPHER_MASK,
233 	.type = CRYPTO_ALG_TYPE_BLKCIPHER,
234 	.tfmsize = offsetof(struct crypto_skcipher, base),
235 };
236 
237 struct crypto_skcipher *crypto_alloc_skcipher(const char *alg_name,
238 					      u32 type, u32 mask)
239 {
240 	return crypto_alloc_tfm(alg_name, &crypto_skcipher_type2, type, mask);
241 }
242 EXPORT_SYMBOL_GPL(crypto_alloc_skcipher);
243 
244 MODULE_LICENSE("GPL");
245 MODULE_DESCRIPTION("Symmetric key cipher type");
246