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