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
  24 struct crypto_pcbc_ctx {
  25         struct crypto_cipher *child;
  26 };
  27
  28 static int crypto_pcbc_setkey(struct crypto_skcipher *parent, const u8 *key,
  29                               unsigned int keylen)
  30 {
  31         struct crypto_pcbc_ctx *ctx = crypto_skcipher_ctx(parent);
  32         struct crypto_cipher *child = ctx->child;
  33         int err;
  34
  35         crypto_cipher_clear_flags(child, CRYPTO_TFM_REQ_MASK);
  36         crypto_cipher_set_flags(child, crypto_skcipher_get_flags(parent) &
  37                                        CRYPTO_TFM_REQ_MASK);
  38         err = crypto_cipher_setkey(child, key, keylen);
  39         crypto_skcipher_set_flags(parent, crypto_cipher_get_flags(child) &
  40                                           CRYPTO_TFM_RES_MASK);
  41         return err;
  42 }
  43
  44 static int crypto_pcbc_encrypt_segment(struct skcipher_request *req,
  45                                        struct skcipher_walk *walk,
  46                                        struct crypto_cipher *tfm)
  47 {
  48         int bsize = crypto_cipher_blocksize(tfm);
  49         unsigned int nbytes = walk->nbytes;
  50         u8 *src = walk->src.virt.addr;
  51         u8 *dst = walk->dst.virt.addr;
  52         u8 *iv = walk->iv;
  53
  54         do {
  55                 crypto_xor(iv, src, bsize);
  56                 crypto_cipher_encrypt_one(tfm, dst, iv);
  57                 memcpy(iv, dst, bsize);
  58                 crypto_xor(iv, 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                 memcpy(iv, tmpbuf, bsize);
  82                 crypto_xor(iv, 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                 memcpy(iv, src, bsize);
 130                 crypto_xor(iv, dst, bsize);
 131
 132                 src += bsize;
 133                 dst += bsize;
 134         } while ((nbytes -= bsize) >= bsize);
 135
 136         memcpy(walk->iv, iv, bsize);
 137
 138         return nbytes;
 139 }
 140
 141 static int crypto_pcbc_decrypt_inplace(struct skcipher_request *req,
 142                                        struct skcipher_walk *walk,
 143                                        struct crypto_cipher *tfm)
 144 {
 145         int bsize = crypto_cipher_blocksize(tfm);
 146         unsigned int nbytes = walk->nbytes;
 147         u8 *src = walk->src.virt.addr;
 148         u8 *iv = walk->iv;
 149         u8 tmpbuf[bsize] __attribute__ ((aligned(__alignof__(u32))));
 150
 151         do {
 152                 memcpy(tmpbuf, src, bsize);
 153                 crypto_cipher_decrypt_one(tfm, src, src);
 154                 crypto_xor(src, iv, bsize);
 155                 memcpy(iv, tmpbuf, bsize);
 156                 crypto_xor(iv, src, bsize);
 157
 158                 src += bsize;
 159         } while ((nbytes -= bsize) >= bsize);
 160
 161         memcpy(walk->iv, iv, bsize);
 162
 163         return nbytes;
 164 }
 165
 166 static int crypto_pcbc_decrypt(struct skcipher_request *req)
 167 {
 168         struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
 169         struct crypto_pcbc_ctx *ctx = crypto_skcipher_ctx(tfm);
 170         struct crypto_cipher *child = ctx->child;
 171         struct skcipher_walk walk;
 172         unsigned int nbytes;
 173         int err;
 174
 175         err = skcipher_walk_virt(&walk, req, false);
 176
 177         while ((nbytes = walk.nbytes)) {
 178                 if (walk.src.virt.addr == walk.dst.virt.addr)
 179                         nbytes = crypto_pcbc_decrypt_inplace(req, &walk,
 180                                                              child);
 181                 else
 182                         nbytes = crypto_pcbc_decrypt_segment(req, &walk,
 183                                                              child);
 184                 err = skcipher_walk_done(&walk, nbytes);
 185         }
 186
 187         return err;
 188 }
 189
 190 static int crypto_pcbc_init_tfm(struct crypto_skcipher *tfm)
 191 {
 192         struct skcipher_instance *inst = skcipher_alg_instance(tfm);
 193         struct crypto_spawn *spawn = skcipher_instance_ctx(inst);
 194         struct crypto_pcbc_ctx *ctx = crypto_skcipher_ctx(tfm);
 195         struct crypto_cipher *cipher;
 196
 197         cipher = crypto_spawn_cipher(spawn);
 198         if (IS_ERR(cipher))
 199                 return PTR_ERR(cipher);
 200
 201         ctx->child = cipher;
 202         return 0;
 203 }
 204
 205 static void crypto_pcbc_exit_tfm(struct crypto_skcipher *tfm)
 206 {
 207         struct crypto_pcbc_ctx *ctx = crypto_skcipher_ctx(tfm);
 208
 209         crypto_free_cipher(ctx->child);
 210 }
 211
 212 static void crypto_pcbc_free(struct skcipher_instance *inst)
 213 {
 214         crypto_drop_skcipher(skcipher_instance_ctx(inst));
 215         kfree(inst);
 216 }
 217
 218 static int crypto_pcbc_create(struct crypto_template *tmpl, struct rtattr **tb)
 219 {
 220         struct skcipher_instance *inst;
 221         struct crypto_attr_type *algt;
 222         struct crypto_spawn *spawn;
 223         struct crypto_alg *alg;
 224         int err;
 225
 226         algt = crypto_get_attr_type(tb);
 227         if (IS_ERR(algt))
 228                 return PTR_ERR(algt);
 229
 230         if (((algt->type ^ CRYPTO_ALG_TYPE_SKCIPHER) & algt->mask) &
 231             ~CRYPTO_ALG_INTERNAL)
 232                 return -EINVAL;
 233
 234         inst = kzalloc(sizeof(*inst) + sizeof(*spawn), GFP_KERNEL);
 235         if (!inst)
 236                 return -ENOMEM;
 237
 238         alg = crypto_get_attr_alg(tb, CRYPTO_ALG_TYPE_CIPHER |
 239                                       (algt->type & CRYPTO_ALG_INTERNAL),
 240                                   CRYPTO_ALG_TYPE_MASK |
 241                                   (algt->mask & CRYPTO_ALG_INTERNAL));
 242         err = PTR_ERR(alg);
 243         if (IS_ERR(alg))
 244                 goto err_free_inst;
 245
 246         spawn = skcipher_instance_ctx(inst);
 247         err = crypto_init_spawn(spawn, alg, skcipher_crypto_instance(inst),
 248                                 CRYPTO_ALG_TYPE_MASK);
 249         crypto_mod_put(alg);
 250         if (err)
 251                 goto err_free_inst;
 252
 253         err = crypto_inst_setname(skcipher_crypto_instance(inst), "pcbc", alg);
 254         if (err)
 255                 goto err_drop_spawn;
 256
 257         inst->alg.base.cra_flags = alg->cra_flags & CRYPTO_ALG_INTERNAL;
 258         inst->alg.base.cra_priority = alg->cra_priority;
 259         inst->alg.base.cra_blocksize = alg->cra_blocksize;
 260         inst->alg.base.cra_alignmask = alg->cra_alignmask;
 261
 262         /* We access the data as u32s when xoring. */
 263         inst->alg.base.cra_alignmask |= __alignof__(u32) - 1;
 264
 265         inst->alg.ivsize = alg->cra_blocksize;
 266         inst->alg.min_keysize = alg->cra_cipher.cia_min_keysize;
 267         inst->alg.max_keysize = alg->cra_cipher.cia_max_keysize;
 268
 269         inst->alg.base.cra_ctxsize = sizeof(struct crypto_pcbc_ctx);
 270
 271         inst->alg.init = crypto_pcbc_init_tfm;
 272         inst->alg.exit = crypto_pcbc_exit_tfm;
 273
 274         inst->alg.setkey = crypto_pcbc_setkey;
 275         inst->alg.encrypt = crypto_pcbc_encrypt;
 276         inst->alg.decrypt = crypto_pcbc_decrypt;
 277
 278         inst->free = crypto_pcbc_free;
 279
 280         err = skcipher_register_instance(tmpl, inst);
 281         if (err)
 282                 goto err_drop_spawn;
 283
 284 out:
 285         return err;
 286
 287 err_drop_spawn:
 288         crypto_drop_spawn(spawn);
 289 err_free_inst:
 290         kfree(inst);
 291         goto out;
 292 }
 293
 294 static struct crypto_template crypto_pcbc_tmpl = {
 295         .name = "pcbc",
 296         .create = crypto_pcbc_create,
 297         .module = THIS_MODULE,
 298 };
 299
 300 static int __init crypto_pcbc_module_init(void)
 301 {
 302         return crypto_register_template(&crypto_pcbc_tmpl);
 303 }
 304
 305 static void __exit crypto_pcbc_module_exit(void)
 306 {
 307         crypto_unregister_template(&crypto_pcbc_tmpl);
 308 }
 309
 310 module_init(crypto_pcbc_module_init);
 311 module_exit(crypto_pcbc_module_exit);
 312
 313 MODULE_LICENSE("GPL");
 314 MODULE_DESCRIPTION("PCBC block cipher algorithm");
 315 MODULE_ALIAS_CRYPTO("pcbc");