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/algapi.h> 14 #include <crypto/cbc.h> 15 #include <crypto/internal/skcipher.h> 16 #include <linux/err.h> 17 #include <linux/init.h> 18 #include <linux/kernel.h> 19 #include <linux/log2.h> 20 #include <linux/module.h> 21 22 static inline void crypto_cbc_encrypt_one(struct crypto_skcipher *tfm, 23 const u8 *src, u8 *dst) 24 { 25 crypto_cipher_encrypt_one(skcipher_cipher_simple(tfm), dst, src); 26 } 27 28 static int crypto_cbc_encrypt(struct skcipher_request *req) 29 { 30 return crypto_cbc_encrypt_walk(req, crypto_cbc_encrypt_one); 31 } 32 33 static inline void crypto_cbc_decrypt_one(struct crypto_skcipher *tfm, 34 const u8 *src, u8 *dst) 35 { 36 crypto_cipher_decrypt_one(skcipher_cipher_simple(tfm), dst, src); 37 } 38 39 static int crypto_cbc_decrypt(struct skcipher_request *req) 40 { 41 struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req); 42 struct skcipher_walk walk; 43 int err; 44 45 err = skcipher_walk_virt(&walk, req, false); 46 47 while (walk.nbytes) { 48 err = crypto_cbc_decrypt_blocks(&walk, tfm, 49 crypto_cbc_decrypt_one); 50 err = skcipher_walk_done(&walk, err); 51 } 52 53 return err; 54 } 55 56 static int crypto_cbc_create(struct crypto_template *tmpl, struct rtattr **tb) 57 { 58 struct skcipher_instance *inst; 59 struct crypto_alg *alg; 60 int err; 61 62 inst = skcipher_alloc_instance_simple(tmpl, tb, &alg); 63 if (IS_ERR(inst)) 64 return PTR_ERR(inst); 65 66 err = -EINVAL; 67 if (!is_power_of_2(alg->cra_blocksize)) 68 goto out_free_inst; 69 70 inst->alg.encrypt = crypto_cbc_encrypt; 71 inst->alg.decrypt = crypto_cbc_decrypt; 72 73 err = skcipher_register_instance(tmpl, inst); 74 if (err) 75 goto out_free_inst; 76 goto out_put_alg; 77 78 out_free_inst: 79 inst->free(inst); 80 out_put_alg: 81 crypto_mod_put(alg); 82 return err; 83 } 84 85 static struct crypto_template crypto_cbc_tmpl = { 86 .name = "cbc", 87 .create = crypto_cbc_create, 88 .module = THIS_MODULE, 89 }; 90 91 static int __init crypto_cbc_module_init(void) 92 { 93 return crypto_register_template(&crypto_cbc_tmpl); 94 } 95 96 static void __exit crypto_cbc_module_exit(void) 97 { 98 crypto_unregister_template(&crypto_cbc_tmpl); 99 } 100 101 module_init(crypto_cbc_module_init); 102 module_exit(crypto_cbc_module_exit); 103 104 MODULE_LICENSE("GPL"); 105 MODULE_DESCRIPTION("CBC block cipher mode of operation"); 106 MODULE_ALIAS_CRYPTO("cbc"); 107