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