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Linux/crypto/cbc.c

  1 /*
  2  * CBC: Cipher Block Chaining mode
  3  *
  4  * Copyright (c) 2006-2016 Herbert Xu <herbert@gondor.apana.org.au>
  5  *
  6  * This program is free software; you can redistribute it and/or modify it
  7  * under the terms of the GNU General Public License as published by the Free
  8  * Software Foundation; either version 2 of the License, or (at your option)
  9  * any later version.
 10  *
 11  */
 12 
 13 #include <crypto/cbc.h>
 14 #include <crypto/internal/skcipher.h>
 15 #include <linux/err.h>
 16 #include <linux/init.h>
 17 #include <linux/kernel.h>
 18 #include <linux/log2.h>
 19 #include <linux/module.h>
 20 #include <linux/slab.h>
 21 
 22 struct crypto_cbc_ctx {
 23         struct crypto_cipher *child;
 24 };
 25 
 26 static int crypto_cbc_setkey(struct crypto_skcipher *parent, const u8 *key,
 27                              unsigned int keylen)
 28 {
 29         struct crypto_cbc_ctx *ctx = crypto_skcipher_ctx(parent);
 30         struct crypto_cipher *child = ctx->child;
 31         int err;
 32 
 33         crypto_cipher_clear_flags(child, CRYPTO_TFM_REQ_MASK);
 34         crypto_cipher_set_flags(child, crypto_skcipher_get_flags(parent) &
 35                                        CRYPTO_TFM_REQ_MASK);
 36         err = crypto_cipher_setkey(child, key, keylen);
 37         crypto_skcipher_set_flags(parent, crypto_cipher_get_flags(child) &
 38                                           CRYPTO_TFM_RES_MASK);
 39         return err;
 40 }
 41 
 42 static inline void crypto_cbc_encrypt_one(struct crypto_skcipher *tfm,
 43                                           const u8 *src, u8 *dst)
 44 {
 45         struct crypto_cbc_ctx *ctx = crypto_skcipher_ctx(tfm);
 46 
 47         crypto_cipher_encrypt_one(ctx->child, dst, src);
 48 }
 49 
 50 static int crypto_cbc_encrypt(struct skcipher_request *req)
 51 {
 52         return crypto_cbc_encrypt_walk(req, crypto_cbc_encrypt_one);
 53 }
 54 
 55 static inline void crypto_cbc_decrypt_one(struct crypto_skcipher *tfm,
 56                                           const u8 *src, u8 *dst)
 57 {
 58         struct crypto_cbc_ctx *ctx = crypto_skcipher_ctx(tfm);
 59 
 60         crypto_cipher_decrypt_one(ctx->child, dst, src);
 61 }
 62 
 63 static int crypto_cbc_decrypt(struct skcipher_request *req)
 64 {
 65         struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
 66         struct skcipher_walk walk;
 67         int err;
 68 
 69         err = skcipher_walk_virt(&walk, req, false);
 70 
 71         while (walk.nbytes) {
 72                 err = crypto_cbc_decrypt_blocks(&walk, tfm,
 73                                                 crypto_cbc_decrypt_one);
 74                 err = skcipher_walk_done(&walk, err);
 75         }
 76 
 77         return err;
 78 }
 79 
 80 static int crypto_cbc_init_tfm(struct crypto_skcipher *tfm)
 81 {
 82         struct skcipher_instance *inst = skcipher_alg_instance(tfm);
 83         struct crypto_spawn *spawn = skcipher_instance_ctx(inst);
 84         struct crypto_cbc_ctx *ctx = crypto_skcipher_ctx(tfm);
 85         struct crypto_cipher *cipher;
 86 
 87         cipher = crypto_spawn_cipher(spawn);
 88         if (IS_ERR(cipher))
 89                 return PTR_ERR(cipher);
 90 
 91         ctx->child = cipher;
 92         return 0;
 93 }
 94 
 95 static void crypto_cbc_exit_tfm(struct crypto_skcipher *tfm)
 96 {
 97         struct crypto_cbc_ctx *ctx = crypto_skcipher_ctx(tfm);
 98 
 99         crypto_free_cipher(ctx->child);
100 }
101 
102 static void crypto_cbc_free(struct skcipher_instance *inst)
103 {
104         crypto_drop_skcipher(skcipher_instance_ctx(inst));
105         kfree(inst);
106 }
107 
108 static int crypto_cbc_create(struct crypto_template *tmpl, struct rtattr **tb)
109 {
110         struct skcipher_instance *inst;
111         struct crypto_spawn *spawn;
112         struct crypto_alg *alg;
113         int err;
114 
115         err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_SKCIPHER);
116         if (err)
117                 return err;
118 
119         inst = kzalloc(sizeof(*inst) + sizeof(*spawn), GFP_KERNEL);
120         if (!inst)
121                 return -ENOMEM;
122 
123         alg = crypto_get_attr_alg(tb, CRYPTO_ALG_TYPE_CIPHER,
124                                   CRYPTO_ALG_TYPE_MASK);
125         err = PTR_ERR(alg);
126         if (IS_ERR(alg))
127                 goto err_free_inst;
128 
129         spawn = skcipher_instance_ctx(inst);
130         err = crypto_init_spawn(spawn, alg, skcipher_crypto_instance(inst),
131                                 CRYPTO_ALG_TYPE_MASK);
132         crypto_mod_put(alg);
133         if (err)
134                 goto err_free_inst;
135 
136         err = crypto_inst_setname(skcipher_crypto_instance(inst), "cbc", alg);
137         if (err)
138                 goto err_drop_spawn;
139 
140         err = -EINVAL;
141         if (!is_power_of_2(alg->cra_blocksize))
142                 goto err_drop_spawn;
143 
144         inst->alg.base.cra_priority = alg->cra_priority;
145         inst->alg.base.cra_blocksize = alg->cra_blocksize;
146         inst->alg.base.cra_alignmask = alg->cra_alignmask;
147 
148         /* We access the data as u32s when xoring. */
149         inst->alg.base.cra_alignmask |= __alignof__(u32) - 1;
150 
151         inst->alg.ivsize = alg->cra_blocksize;
152         inst->alg.min_keysize = alg->cra_cipher.cia_min_keysize;
153         inst->alg.max_keysize = alg->cra_cipher.cia_max_keysize;
154 
155         inst->alg.base.cra_ctxsize = sizeof(struct crypto_cbc_ctx);
156 
157         inst->alg.init = crypto_cbc_init_tfm;
158         inst->alg.exit = crypto_cbc_exit_tfm;
159 
160         inst->alg.setkey = crypto_cbc_setkey;
161         inst->alg.encrypt = crypto_cbc_encrypt;
162         inst->alg.decrypt = crypto_cbc_decrypt;
163 
164         inst->free = crypto_cbc_free;
165 
166         err = skcipher_register_instance(tmpl, inst);
167         if (err)
168                 goto err_drop_spawn;
169 
170 out:
171         return err;
172 
173 err_drop_spawn:
174         crypto_drop_spawn(spawn);
175 err_free_inst:
176         kfree(inst);
177         goto out;
178 }
179 
180 static struct crypto_template crypto_cbc_tmpl = {
181         .name = "cbc",
182         .create = crypto_cbc_create,
183         .module = THIS_MODULE,
184 };
185 
186 static int __init crypto_cbc_module_init(void)
187 {
188         return crypto_register_template(&crypto_cbc_tmpl);
189 }
190 
191 static void __exit crypto_cbc_module_exit(void)
192 {
193         crypto_unregister_template(&crypto_cbc_tmpl);
194 }
195 
196 module_init(crypto_cbc_module_init);
197 module_exit(crypto_cbc_module_exit);
198 
199 MODULE_LICENSE("GPL");
200 MODULE_DESCRIPTION("CBC block cipher algorithm");
201 MODULE_ALIAS_CRYPTO("cbc");
202 

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