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 *iv = walk->iv;
  54
  55         do {
  56                 crypto_xor(iv, src, bsize);
  57                 crypto_cipher_encrypt_one(tfm, dst, iv);
  58                 memcpy(iv, dst, bsize);
  59                 crypto_xor(iv, 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 *iv = walk->iv;
  76         u8 tmpbuf[bsize];
  77
  78         do {
  79                 memcpy(tmpbuf, src, bsize);
  80                 crypto_xor(iv, src, bsize);
  81                 crypto_cipher_encrypt_one(tfm, src, iv);
  82                 memcpy(iv, tmpbuf, bsize);
  83                 crypto_xor(iv, src, bsize);
  84
  85                 src += bsize;
  86         } while ((nbytes -= bsize) >= bsize);
  87
  88         memcpy(walk->iv, iv, bsize);
  89
  90         return nbytes;
  91 }
  92
  93 static int crypto_pcbc_encrypt(struct skcipher_request *req)
  94 {
  95         struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
  96         struct crypto_pcbc_ctx *ctx = crypto_skcipher_ctx(tfm);
  97         struct crypto_cipher *child = ctx->child;
  98         struct skcipher_walk walk;
  99         unsigned int nbytes;
 100         int err;
 101
 102         err = skcipher_walk_virt(&walk, req, false);
 103
 104         while ((nbytes = walk.nbytes)) {
 105                 if (walk.src.virt.addr == walk.dst.virt.addr)
 106                         nbytes = crypto_pcbc_encrypt_inplace(req, &walk,
 107                                                              child);
 108                 else
 109                         nbytes = crypto_pcbc_encrypt_segment(req, &walk,
 110                                                              child);
 111                 err = skcipher_walk_done(&walk, nbytes);
 112         }
 113
 114         return err;
 115 }
 116
 117 static int crypto_pcbc_decrypt_segment(struct skcipher_request *req,
 118                                        struct skcipher_walk *walk,
 119                                        struct crypto_cipher *tfm)
 120 {
 121         int bsize = crypto_cipher_blocksize(tfm);
 122         unsigned int nbytes = walk->nbytes;
 123         u8 *src = walk->src.virt.addr;
 124         u8 *dst = walk->dst.virt.addr;
 125         u8 *iv = walk->iv;
 126
 127         do {
 128                 crypto_cipher_decrypt_one(tfm, dst, src);
 129                 crypto_xor(dst, iv, bsize);
 130                 memcpy(iv, src, bsize);
 131                 crypto_xor(iv, dst, bsize);
 132
 133                 src += bsize;
 134                 dst += bsize;
 135         } while ((nbytes -= bsize) >= bsize);
 136
 137         memcpy(walk->iv, iv, bsize);
 138
 139         return nbytes;
 140 }
 141
 142 static int crypto_pcbc_decrypt_inplace(struct skcipher_request *req,
 143                                        struct skcipher_walk *walk,
 144                                        struct crypto_cipher *tfm)
 145 {
 146         int bsize = crypto_cipher_blocksize(tfm);
 147         unsigned int nbytes = walk->nbytes;
 148         u8 *src = walk->src.virt.addr;
 149         u8 *iv = walk->iv;
 150         u8 tmpbuf[bsize] __aligned(__alignof__(u32));
 151
 152         do {
 153                 memcpy(tmpbuf, src, bsize);
 154                 crypto_cipher_decrypt_one(tfm, src, src);
 155                 crypto_xor(src, iv, bsize);
 156                 memcpy(iv, tmpbuf, bsize);
 157                 crypto_xor(iv, src, bsize);
 158
 159                 src += bsize;
 160         } while ((nbytes -= bsize) >= bsize);
 161
 162         memcpy(walk->iv, iv, bsize);
 163
 164         return nbytes;
 165 }
 166
 167 static int crypto_pcbc_decrypt(struct skcipher_request *req)
 168 {
 169         struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
 170         struct crypto_pcbc_ctx *ctx = crypto_skcipher_ctx(tfm);
 171         struct crypto_cipher *child = ctx->child;
 172         struct skcipher_walk walk;
 173         unsigned int nbytes;
 174         int err;
 175
 176         err = skcipher_walk_virt(&walk, req, false);
 177
 178         while ((nbytes = walk.nbytes)) {
 179                 if (walk.src.virt.addr == walk.dst.virt.addr)
 180                         nbytes = crypto_pcbc_decrypt_inplace(req, &walk,
 181                                                              child);
 182                 else
 183                         nbytes = crypto_pcbc_decrypt_segment(req, &walk,
 184                                                              child);
 185                 err = skcipher_walk_done(&walk, nbytes);
 186         }
 187
 188         return err;
 189 }
 190
 191 static int crypto_pcbc_init_tfm(struct crypto_skcipher *tfm)
 192 {
 193         struct skcipher_instance *inst = skcipher_alg_instance(tfm);
 194         struct crypto_spawn *spawn = skcipher_instance_ctx(inst);
 195         struct crypto_pcbc_ctx *ctx = crypto_skcipher_ctx(tfm);
 196         struct crypto_cipher *cipher;
 197
 198         cipher = crypto_spawn_cipher(spawn);
 199         if (IS_ERR(cipher))
 200                 return PTR_ERR(cipher);
 201
 202         ctx->child = cipher;
 203         return 0;
 204 }
 205
 206 static void crypto_pcbc_exit_tfm(struct crypto_skcipher *tfm)
 207 {
 208         struct crypto_pcbc_ctx *ctx = crypto_skcipher_ctx(tfm);
 209
 210         crypto_free_cipher(ctx->child);
 211 }
 212
 213 static void crypto_pcbc_free(struct skcipher_instance *inst)
 214 {
 215         crypto_drop_skcipher(skcipher_instance_ctx(inst));
 216         kfree(inst);
 217 }
 218
 219 static int crypto_pcbc_create(struct crypto_template *tmpl, struct rtattr **tb)
 220 {
 221         struct skcipher_instance *inst;
 222         struct crypto_attr_type *algt;
 223         struct crypto_spawn *spawn;
 224         struct crypto_alg *alg;
 225         int err;
 226
 227         algt = crypto_get_attr_type(tb);
 228         if (IS_ERR(algt))
 229                 return PTR_ERR(algt);
 230
 231         if (((algt->type ^ CRYPTO_ALG_TYPE_SKCIPHER) & algt->mask) &
 232             ~CRYPTO_ALG_INTERNAL)
 233                 return -EINVAL;
 234
 235         inst = kzalloc(sizeof(*inst) + sizeof(*spawn), GFP_KERNEL);
 236         if (!inst)
 237                 return -ENOMEM;
 238
 239         alg = crypto_get_attr_alg(tb, CRYPTO_ALG_TYPE_CIPHER |
 240                                       (algt->type & CRYPTO_ALG_INTERNAL),
 241                                   CRYPTO_ALG_TYPE_MASK |
 242                                   (algt->mask & CRYPTO_ALG_INTERNAL));
 243         err = PTR_ERR(alg);
 244         if (IS_ERR(alg))
 245                 goto err_free_inst;
 246
 247         spawn = skcipher_instance_ctx(inst);
 248         err = crypto_init_spawn(spawn, alg, skcipher_crypto_instance(inst),
 249                                 CRYPTO_ALG_TYPE_MASK);
 250         crypto_mod_put(alg);
 251         if (err)
 252                 goto err_free_inst;
 253
 254         err = crypto_inst_setname(skcipher_crypto_instance(inst), "pcbc", alg);
 255         if (err)
 256                 goto err_drop_spawn;
 257
 258         inst->alg.base.cra_flags = alg->cra_flags & CRYPTO_ALG_INTERNAL;
 259         inst->alg.base.cra_priority = alg->cra_priority;
 260         inst->alg.base.cra_blocksize = alg->cra_blocksize;
 261         inst->alg.base.cra_alignmask = alg->cra_alignmask;
 262
 263         inst->alg.ivsize = alg->cra_blocksize;
 264         inst->alg.min_keysize = alg->cra_cipher.cia_min_keysize;
 265         inst->alg.max_keysize = alg->cra_cipher.cia_max_keysize;
 266
 267         inst->alg.base.cra_ctxsize = sizeof(struct crypto_pcbc_ctx);
 268
 269         inst->alg.init = crypto_pcbc_init_tfm;
 270         inst->alg.exit = crypto_pcbc_exit_tfm;
 271
 272         inst->alg.setkey = crypto_pcbc_setkey;
 273         inst->alg.encrypt = crypto_pcbc_encrypt;
 274         inst->alg.decrypt = crypto_pcbc_decrypt;
 275
 276         inst->free = crypto_pcbc_free;
 277
 278         err = skcipher_register_instance(tmpl, inst);
 279         if (err)
 280                 goto err_drop_spawn;
 281
 282 out:
 283         return err;
 284
 285 err_drop_spawn:
 286         crypto_drop_spawn(spawn);
 287 err_free_inst:
 288         kfree(inst);
 289         goto out;
 290 }
 291
 292 static struct crypto_template crypto_pcbc_tmpl = {
 293         .name = "pcbc",
 294         .create = crypto_pcbc_create,
 295         .module = THIS_MODULE,
 296 };
 297
 298 static int __init crypto_pcbc_module_init(void)
 299 {
 300         return crypto_register_template(&crypto_pcbc_tmpl);
 301 }
 302
 303 static void __exit crypto_pcbc_module_exit(void)
 304 {
 305         crypto_unregister_template(&crypto_pcbc_tmpl);
 306 }
 307
 308 module_init(crypto_pcbc_module_init);
 309 module_exit(crypto_pcbc_module_exit);
 310
 311 MODULE_LICENSE("GPL");
 312 MODULE_DESCRIPTION("PCBC block cipher algorithm");
 313 MODULE_ALIAS_CRYPTO("pcbc");