crypto/pcbc.c

   1 /*
   2  * PCBC: Propagating Cipher Block Chaining mode
   3  *
   4  * Copyright (C) 2006 Red Hat, Inc. All Rights Reserved.
   5  * Written by David Howells (dhowells@redhat.com)
   6  *
   7  * Derived from cbc.c
   8  * - Copyright (c) 2006 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/algapi.h>
  18 #include <crypto/internal/skcipher.h>
  19 #include <linux/err.h>
  20 #include <linux/init.h>
  21 #include <linux/kernel.h>
  22 #include <linux/module.h>
  23 #include <linux/slab.h>
  24 #include <linux/compiler.h>
  25
  26 struct crypto_pcbc_ctx {
  27         struct crypto_cipher *child;
  28 };
  29
  30 static int crypto_pcbc_setkey(struct crypto_skcipher *parent, const u8 *key,
  31                               unsigned int keylen)
  32 {
  33         struct crypto_pcbc_ctx *ctx = crypto_skcipher_ctx(parent);
  34         struct crypto_cipher *child = ctx->child;
  35         int err;
  36
  37         crypto_cipher_clear_flags(child, CRYPTO_TFM_REQ_MASK);
  38         crypto_cipher_set_flags(child, crypto_skcipher_get_flags(parent) &
  39                                        CRYPTO_TFM_REQ_MASK);
  40         err = crypto_cipher_setkey(child, key, keylen);
  41         crypto_skcipher_set_flags(parent, crypto_cipher_get_flags(child) &
  42                                           CRYPTO_TFM_RES_MASK);
  43         return err;
  44 }
  45
  46 static int crypto_pcbc_encrypt_segment(struct skcipher_request *req,
  47                                        struct skcipher_walk *walk,
  48                                        struct crypto_cipher *tfm)
  49 {
  50         int bsize = crypto_cipher_blocksize(tfm);
  51         unsigned int nbytes = walk->nbytes;
  52         u8 *src = walk->src.virt.addr;
  53         u8 *dst = walk->dst.virt.addr;
  54         u8 * const iv = walk->iv;
  55
  56         do {
  57                 crypto_xor(iv, src, bsize);
  58                 crypto_cipher_encrypt_one(tfm, dst, iv);
  59                 crypto_xor_cpy(iv, dst, src, bsize);
  60
  61                 src += bsize;
  62                 dst += bsize;
  63         } while ((nbytes -= bsize) >= bsize);
  64
  65         return nbytes;
  66 }
  67
  68 static int crypto_pcbc_encrypt_inplace(struct skcipher_request *req,
  69                                        struct skcipher_walk *walk,
  70                                        struct crypto_cipher *tfm)
  71 {
  72         int bsize = crypto_cipher_blocksize(tfm);
  73         unsigned int nbytes = walk->nbytes;
  74         u8 *src = walk->src.virt.addr;
  75         u8 * const iv = walk->iv;
  76         u8 tmpbuf[MAX_CIPHER_BLOCKSIZE];
  77
  78         do {
  79                 memcpy(tmpbuf, src, bsize);
  80                 crypto_xor(iv, src, bsize);
  81                 crypto_cipher_encrypt_one(tfm, src, iv);
  82                 crypto_xor_cpy(iv, tmpbuf, src, bsize);
  83
  84                 src += bsize;
  85         } while ((nbytes -= bsize) >= bsize);
  86
  87         return nbytes;
  88 }
  89
  90 static int crypto_pcbc_encrypt(struct skcipher_request *req)
  91 {
  92         struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
  93         struct crypto_pcbc_ctx *ctx = crypto_skcipher_ctx(tfm);
  94         struct crypto_cipher *child = ctx->child;
  95         struct skcipher_walk walk;
  96         unsigned int nbytes;
  97         int err;
  98
  99         err = skcipher_walk_virt(&walk, req, false);
 100
 101         while ((nbytes = walk.nbytes)) {
 102                 if (walk.src.virt.addr == walk.dst.virt.addr)
 103                         nbytes = crypto_pcbc_encrypt_inplace(req, &walk,
 104                                                              child);
 105                 else
 106                         nbytes = crypto_pcbc_encrypt_segment(req, &walk,
 107                                                              child);
 108                 err = skcipher_walk_done(&walk, nbytes);
 109         }
 110
 111         return err;
 112 }
 113
 114 static int crypto_pcbc_decrypt_segment(struct skcipher_request *req,
 115                                        struct skcipher_walk *walk,
 116                                        struct crypto_cipher *tfm)
 117 {
 118         int bsize = crypto_cipher_blocksize(tfm);
 119         unsigned int nbytes = walk->nbytes;
 120         u8 *src = walk->src.virt.addr;
 121         u8 *dst = walk->dst.virt.addr;
 122         u8 * const iv = walk->iv;
 123
 124         do {
 125                 crypto_cipher_decrypt_one(tfm, dst, src);
 126                 crypto_xor(dst, iv, bsize);
 127                 crypto_xor_cpy(iv, dst, src, bsize);
 128
 129                 src += bsize;
 130                 dst += bsize;
 131         } while ((nbytes -= bsize) >= bsize);
 132
 133         return nbytes;
 134 }
 135
 136 static int crypto_pcbc_decrypt_inplace(struct skcipher_request *req,
 137                                        struct skcipher_walk *walk,
 138                                        struct crypto_cipher *tfm)
 139 {
 140         int bsize = crypto_cipher_blocksize(tfm);
 141         unsigned int nbytes = walk->nbytes;
 142         u8 *src = walk->src.virt.addr;
 143         u8 * const iv = walk->iv;
 144         u8 tmpbuf[MAX_CIPHER_BLOCKSIZE] __aligned(__alignof__(u32));
 145
 146         do {
 147                 memcpy(tmpbuf, src, bsize);
 148                 crypto_cipher_decrypt_one(tfm, src, src);
 149                 crypto_xor(src, iv, bsize);
 150                 crypto_xor_cpy(iv, src, tmpbuf, bsize);
 151
 152                 src += bsize;
 153         } while ((nbytes -= bsize) >= bsize);
 154
 155         return nbytes;
 156 }
 157
 158 static int crypto_pcbc_decrypt(struct skcipher_request *req)
 159 {
 160         struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
 161         struct crypto_pcbc_ctx *ctx = crypto_skcipher_ctx(tfm);
 162         struct crypto_cipher *child = ctx->child;
 163         struct skcipher_walk walk;
 164         unsigned int nbytes;
 165         int err;
 166
 167         err = skcipher_walk_virt(&walk, req, false);
 168
 169         while ((nbytes = walk.nbytes)) {
 170                 if (walk.src.virt.addr == walk.dst.virt.addr)
 171                         nbytes = crypto_pcbc_decrypt_inplace(req, &walk,
 172                                                              child);
 173                 else
 174                         nbytes = crypto_pcbc_decrypt_segment(req, &walk,
 175                                                              child);
 176                 err = skcipher_walk_done(&walk, nbytes);
 177         }
 178
 179         return err;
 180 }
 181
 182 static int crypto_pcbc_init_tfm(struct crypto_skcipher *tfm)
 183 {
 184         struct skcipher_instance *inst = skcipher_alg_instance(tfm);
 185         struct crypto_spawn *spawn = skcipher_instance_ctx(inst);
 186         struct crypto_pcbc_ctx *ctx = crypto_skcipher_ctx(tfm);
 187         struct crypto_cipher *cipher;
 188
 189         cipher = crypto_spawn_cipher(spawn);
 190         if (IS_ERR(cipher))
 191                 return PTR_ERR(cipher);
 192
 193         ctx->child = cipher;
 194         return 0;
 195 }
 196
 197 static void crypto_pcbc_exit_tfm(struct crypto_skcipher *tfm)
 198 {
 199         struct crypto_pcbc_ctx *ctx = crypto_skcipher_ctx(tfm);
 200
 201         crypto_free_cipher(ctx->child);
 202 }
 203
 204 static void crypto_pcbc_free(struct skcipher_instance *inst)
 205 {
 206         crypto_drop_skcipher(skcipher_instance_ctx(inst));
 207         kfree(inst);
 208 }
 209
 210 static int crypto_pcbc_create(struct crypto_template *tmpl, struct rtattr **tb)
 211 {
 212         struct skcipher_instance *inst;
 213         struct crypto_attr_type *algt;
 214         struct crypto_spawn *spawn;
 215         struct crypto_alg *alg;
 216         int err;
 217
 218         algt = crypto_get_attr_type(tb);
 219         if (IS_ERR(algt))
 220                 return PTR_ERR(algt);
 221
 222         if (((algt->type ^ CRYPTO_ALG_TYPE_SKCIPHER) & algt->mask) &
 223             ~CRYPTO_ALG_INTERNAL)
 224                 return -EINVAL;
 225
 226         inst = kzalloc(sizeof(*inst) + sizeof(*spawn), GFP_KERNEL);
 227         if (!inst)
 228                 return -ENOMEM;
 229
 230         alg = crypto_get_attr_alg(tb, CRYPTO_ALG_TYPE_CIPHER |
 231                                       (algt->type & CRYPTO_ALG_INTERNAL),
 232                                   CRYPTO_ALG_TYPE_MASK |
 233                                   (algt->mask & CRYPTO_ALG_INTERNAL));
 234         err = PTR_ERR(alg);
 235         if (IS_ERR(alg))
 236                 goto err_free_inst;
 237
 238         spawn = skcipher_instance_ctx(inst);
 239         err = crypto_init_spawn(spawn, alg, skcipher_crypto_instance(inst),
 240                                 CRYPTO_ALG_TYPE_MASK);
 241         if (err)
 242                 goto err_put_alg;
 243
 244         err = crypto_inst_setname(skcipher_crypto_instance(inst), "pcbc", alg);
 245         if (err)
 246                 goto err_drop_spawn;
 247
 248         inst->alg.base.cra_flags = alg->cra_flags & CRYPTO_ALG_INTERNAL;
 249         inst->alg.base.cra_priority = alg->cra_priority;
 250         inst->alg.base.cra_blocksize = alg->cra_blocksize;
 251         inst->alg.base.cra_alignmask = alg->cra_alignmask;
 252
 253         inst->alg.ivsize = alg->cra_blocksize;
 254         inst->alg.min_keysize = alg->cra_cipher.cia_min_keysize;
 255         inst->alg.max_keysize = alg->cra_cipher.cia_max_keysize;
 256
 257         inst->alg.base.cra_ctxsize = sizeof(struct crypto_pcbc_ctx);
 258
 259         inst->alg.init = crypto_pcbc_init_tfm;
 260         inst->alg.exit = crypto_pcbc_exit_tfm;
 261
 262         inst->alg.setkey = crypto_pcbc_setkey;
 263         inst->alg.encrypt = crypto_pcbc_encrypt;
 264         inst->alg.decrypt = crypto_pcbc_decrypt;
 265
 266         inst->free = crypto_pcbc_free;
 267
 268         err = skcipher_register_instance(tmpl, inst);
 269         if (err)
 270                 goto err_drop_spawn;
 271         crypto_mod_put(alg);
 272
 273 out:
 274         return err;
 275
 276 err_drop_spawn:
 277         crypto_drop_spawn(spawn);
 278 err_put_alg:
 279         crypto_mod_put(alg);
 280 err_free_inst:
 281         kfree(inst);
 282         goto out;
 283 }
 284
 285 static struct crypto_template crypto_pcbc_tmpl = {
 286         .name = "pcbc",
 287         .create = crypto_pcbc_create,
 288         .module = THIS_MODULE,
 289 };
 290
 291 static int __init crypto_pcbc_module_init(void)
 292 {
 293         return crypto_register_template(&crypto_pcbc_tmpl);
 294 }
 295
 296 static void __exit crypto_pcbc_module_exit(void)
 297 {
 298         crypto_unregister_template(&crypto_pcbc_tmpl);
 299 }
 300
 301 module_init(crypto_pcbc_module_init);
 302 module_exit(crypto_pcbc_module_exit);
 303
 304 MODULE_LICENSE("GPL");
 305 MODULE_DESCRIPTION("PCBC block cipher algorithm");
 306 MODULE_ALIAS_CRYPTO("pcbc");