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