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/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 #include <linux/slab.h>
  22
  23 struct crypto_cbc_ctx {
  24         struct crypto_cipher *child;
  25 };
  26
  27 static int crypto_cbc_setkey(struct crypto_skcipher *parent, const u8 *key,
  28                              unsigned int keylen)
  29 {
  30         struct crypto_cbc_ctx *ctx = crypto_skcipher_ctx(parent);
  31         struct crypto_cipher *child = ctx->child;
  32         int err;
  33
  34         crypto_cipher_clear_flags(child, CRYPTO_TFM_REQ_MASK);
  35         crypto_cipher_set_flags(child, crypto_skcipher_get_flags(parent) &
  36                                        CRYPTO_TFM_REQ_MASK);
  37         err = crypto_cipher_setkey(child, key, keylen);
  38         crypto_skcipher_set_flags(parent, crypto_cipher_get_flags(child) &
  39                                           CRYPTO_TFM_RES_MASK);
  40         return err;
  41 }
  42
  43 static inline void crypto_cbc_encrypt_one(struct crypto_skcipher *tfm,
  44                                           const u8 *src, u8 *dst)
  45 {
  46         struct crypto_cbc_ctx *ctx = crypto_skcipher_ctx(tfm);
  47
  48         crypto_cipher_encrypt_one(ctx->child, dst, src);
  49 }
  50
  51 static int crypto_cbc_encrypt(struct skcipher_request *req)
  52 {
  53         return crypto_cbc_encrypt_walk(req, crypto_cbc_encrypt_one);
  54 }
  55
  56 static inline void crypto_cbc_decrypt_one(struct crypto_skcipher *tfm,
  57                                           const u8 *src, u8 *dst)
  58 {
  59         struct crypto_cbc_ctx *ctx = crypto_skcipher_ctx(tfm);
  60
  61         crypto_cipher_decrypt_one(ctx->child, dst, src);
  62 }
  63
  64 static int crypto_cbc_decrypt(struct skcipher_request *req)
  65 {
  66         struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
  67         struct skcipher_walk walk;
  68         int err;
  69
  70         err = skcipher_walk_virt(&walk, req, false);
  71
  72         while (walk.nbytes) {
  73                 err = crypto_cbc_decrypt_blocks(&walk, tfm,
  74                                                 crypto_cbc_decrypt_one);
  75                 err = skcipher_walk_done(&walk, err);
  76         }
  77
  78         return err;
  79 }
  80
  81 static int crypto_cbc_init_tfm(struct crypto_skcipher *tfm)
  82 {
  83         struct skcipher_instance *inst = skcipher_alg_instance(tfm);
  84         struct crypto_spawn *spawn = skcipher_instance_ctx(inst);
  85         struct crypto_cbc_ctx *ctx = crypto_skcipher_ctx(tfm);
  86         struct crypto_cipher *cipher;
  87
  88         cipher = crypto_spawn_cipher(spawn);
  89         if (IS_ERR(cipher))
  90                 return PTR_ERR(cipher);
  91
  92         ctx->child = cipher;
  93         return 0;
  94 }
  95
  96 static void crypto_cbc_exit_tfm(struct crypto_skcipher *tfm)
  97 {
  98         struct crypto_cbc_ctx *ctx = crypto_skcipher_ctx(tfm);
  99
 100         crypto_free_cipher(ctx->child);
 101 }
 102
 103 static void crypto_cbc_free(struct skcipher_instance *inst)
 104 {
 105         crypto_drop_skcipher(skcipher_instance_ctx(inst));
 106         kfree(inst);
 107 }
 108
 109 static int crypto_cbc_create(struct crypto_template *tmpl, struct rtattr **tb)
 110 {
 111         struct skcipher_instance *inst;
 112         struct crypto_attr_type *algt;
 113         struct crypto_spawn *spawn;
 114         struct crypto_alg *alg;
 115         u32 mask;
 116         int err;
 117
 118         err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_SKCIPHER);
 119         if (err)
 120                 return err;
 121
 122         inst = kzalloc(sizeof(*inst) + sizeof(*spawn), GFP_KERNEL);
 123         if (!inst)
 124                 return -ENOMEM;
 125
 126         algt = crypto_get_attr_type(tb);
 127         err = PTR_ERR(algt);
 128         if (IS_ERR(algt))
 129                 goto err_free_inst;
 130
 131         mask = CRYPTO_ALG_TYPE_MASK |
 132                 crypto_requires_off(algt->type, algt->mask,
 133                                     CRYPTO_ALG_NEED_FALLBACK);
 134
 135         alg = crypto_get_attr_alg(tb, CRYPTO_ALG_TYPE_CIPHER, mask);
 136         err = PTR_ERR(alg);
 137         if (IS_ERR(alg))
 138                 goto err_free_inst;
 139
 140         spawn = skcipher_instance_ctx(inst);
 141         err = crypto_init_spawn(spawn, alg, skcipher_crypto_instance(inst),
 142                                 CRYPTO_ALG_TYPE_MASK);
 143         if (err)
 144                 goto err_put_alg;
 145
 146         err = crypto_inst_setname(skcipher_crypto_instance(inst), "cbc", alg);
 147         if (err)
 148                 goto err_drop_spawn;
 149
 150         err = -EINVAL;
 151         if (!is_power_of_2(alg->cra_blocksize))
 152                 goto err_drop_spawn;
 153
 154         inst->alg.base.cra_priority = alg->cra_priority;
 155         inst->alg.base.cra_blocksize = alg->cra_blocksize;
 156         inst->alg.base.cra_alignmask = alg->cra_alignmask;
 157
 158         inst->alg.ivsize = alg->cra_blocksize;
 159         inst->alg.min_keysize = alg->cra_cipher.cia_min_keysize;
 160         inst->alg.max_keysize = alg->cra_cipher.cia_max_keysize;
 161
 162         inst->alg.base.cra_ctxsize = sizeof(struct crypto_cbc_ctx);
 163
 164         inst->alg.init = crypto_cbc_init_tfm;
 165         inst->alg.exit = crypto_cbc_exit_tfm;
 166
 167         inst->alg.setkey = crypto_cbc_setkey;
 168         inst->alg.encrypt = crypto_cbc_encrypt;
 169         inst->alg.decrypt = crypto_cbc_decrypt;
 170
 171         inst->free = crypto_cbc_free;
 172
 173         err = skcipher_register_instance(tmpl, inst);
 174         if (err)
 175                 goto err_drop_spawn;
 176         crypto_mod_put(alg);
 177
 178 out:
 179         return err;
 180
 181 err_drop_spawn:
 182         crypto_drop_spawn(spawn);
 183 err_put_alg:
 184         crypto_mod_put(alg);
 185 err_free_inst:
 186         kfree(inst);
 187         goto out;
 188 }
 189
 190 static struct crypto_template crypto_cbc_tmpl = {
 191         .name = "cbc",
 192         .create = crypto_cbc_create,
 193         .module = THIS_MODULE,
 194 };
 195
 196 static int __init crypto_cbc_module_init(void)
 197 {
 198         return crypto_register_template(&crypto_cbc_tmpl);
 199 }
 200
 201 static void __exit crypto_cbc_module_exit(void)
 202 {
 203         crypto_unregister_template(&crypto_cbc_tmpl);
 204 }
 205
 206 module_init(crypto_cbc_module_init);
 207 module_exit(crypto_cbc_module_exit);
 208
 209 MODULE_LICENSE("GPL");
 210 MODULE_DESCRIPTION("CBC block cipher algorithm");
 211 MODULE_ALIAS_CRYPTO("cbc");