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
 23static 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
 34static 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
 51static 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
 69static 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
 78static 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
 87static 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
 94static 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	skcipher->keysize = calg->cra_blkcipher.max_keysize;
122
123	return 0;
124}
125
126static int skcipher_setkey_ablkcipher(struct crypto_skcipher *tfm,
127				      const u8 *key, unsigned int keylen)
128{
129	struct crypto_ablkcipher **ctx = crypto_skcipher_ctx(tfm);
130	struct crypto_ablkcipher *ablkcipher = *ctx;
131	int err;
132
133	crypto_ablkcipher_clear_flags(ablkcipher, ~0);
134	crypto_ablkcipher_set_flags(ablkcipher,
135				    crypto_skcipher_get_flags(tfm) &
136				    CRYPTO_TFM_REQ_MASK);
137	err = crypto_ablkcipher_setkey(ablkcipher, key, keylen);
138	crypto_skcipher_set_flags(tfm,
139				  crypto_ablkcipher_get_flags(ablkcipher) &
140				  CRYPTO_TFM_RES_MASK);
141
142	return err;
143}
144
145static int skcipher_crypt_ablkcipher(struct skcipher_request *req,
146				     int (*crypt)(struct ablkcipher_request *))
147{
148	struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
149	struct crypto_ablkcipher **ctx = crypto_skcipher_ctx(tfm);
150	struct ablkcipher_request *subreq = skcipher_request_ctx(req);
151
152	ablkcipher_request_set_tfm(subreq, *ctx);
153	ablkcipher_request_set_callback(subreq, skcipher_request_flags(req),
154					req->base.complete, req->base.data);
155	ablkcipher_request_set_crypt(subreq, req->src, req->dst, req->cryptlen,
156				     req->iv);
157
158	return crypt(subreq);
159}
160
161static int skcipher_encrypt_ablkcipher(struct skcipher_request *req)
162{
163	struct crypto_skcipher *skcipher = crypto_skcipher_reqtfm(req);
164	struct crypto_tfm *tfm = crypto_skcipher_tfm(skcipher);
165	struct ablkcipher_alg *alg = &tfm->__crt_alg->cra_ablkcipher;
166
167	return skcipher_crypt_ablkcipher(req, alg->encrypt);
168}
169
170static int skcipher_decrypt_ablkcipher(struct skcipher_request *req)
171{
172	struct crypto_skcipher *skcipher = crypto_skcipher_reqtfm(req);
173	struct crypto_tfm *tfm = crypto_skcipher_tfm(skcipher);
174	struct ablkcipher_alg *alg = &tfm->__crt_alg->cra_ablkcipher;
175
176	return skcipher_crypt_ablkcipher(req, alg->decrypt);
177}
178
179static void crypto_exit_skcipher_ops_ablkcipher(struct crypto_tfm *tfm)
180{
181	struct crypto_ablkcipher **ctx = crypto_tfm_ctx(tfm);
182
183	crypto_free_ablkcipher(*ctx);
184}
185
186static int crypto_init_skcipher_ops_ablkcipher(struct crypto_tfm *tfm)
187{
188	struct crypto_alg *calg = tfm->__crt_alg;
189	struct crypto_skcipher *skcipher = __crypto_skcipher_cast(tfm);
190	struct crypto_ablkcipher **ctx = crypto_tfm_ctx(tfm);
191	struct crypto_ablkcipher *ablkcipher;
192	struct crypto_tfm *abtfm;
193
194	if (!crypto_mod_get(calg))
195		return -EAGAIN;
196
197	abtfm = __crypto_alloc_tfm(calg, 0, 0);
198	if (IS_ERR(abtfm)) {
199		crypto_mod_put(calg);
200		return PTR_ERR(abtfm);
201	}
202
203	ablkcipher = __crypto_ablkcipher_cast(abtfm);
204	*ctx = ablkcipher;
205	tfm->exit = crypto_exit_skcipher_ops_ablkcipher;
206
207	skcipher->setkey = skcipher_setkey_ablkcipher;
208	skcipher->encrypt = skcipher_encrypt_ablkcipher;
209	skcipher->decrypt = skcipher_decrypt_ablkcipher;
210
211	skcipher->ivsize = crypto_ablkcipher_ivsize(ablkcipher);
212	skcipher->reqsize = crypto_ablkcipher_reqsize(ablkcipher) +
213			    sizeof(struct ablkcipher_request);
214	skcipher->keysize = calg->cra_ablkcipher.max_keysize;
215
216	return 0;
217}
218
219static int crypto_skcipher_init_tfm(struct crypto_tfm *tfm)
220{
221	if (tfm->__crt_alg->cra_type == &crypto_blkcipher_type)
222		return crypto_init_skcipher_ops_blkcipher(tfm);
223
224	BUG_ON(tfm->__crt_alg->cra_type != &crypto_ablkcipher_type &&
225	       tfm->__crt_alg->cra_type != &crypto_givcipher_type);
226
227	return crypto_init_skcipher_ops_ablkcipher(tfm);
228}
229
230static const struct crypto_type crypto_skcipher_type2 = {
231	.extsize = crypto_skcipher_extsize,
232	.init_tfm = crypto_skcipher_init_tfm,
233	.maskclear = ~CRYPTO_ALG_TYPE_MASK,
234	.maskset = CRYPTO_ALG_TYPE_BLKCIPHER_MASK,
235	.type = CRYPTO_ALG_TYPE_BLKCIPHER,
236	.tfmsize = offsetof(struct crypto_skcipher, base),
237};
238
239struct crypto_skcipher *crypto_alloc_skcipher(const char *alg_name,
240					      u32 type, u32 mask)
241{
242	return crypto_alloc_tfm(alg_name, &crypto_skcipher_type2, type, mask);
243}
244EXPORT_SYMBOL_GPL(crypto_alloc_skcipher);
245
246MODULE_LICENSE("GPL");
247MODULE_DESCRIPTION("Symmetric key cipher type");