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 <linux/err.h>
  19 #include <linux/init.h>
  20 #include <linux/kernel.h>
  21 #include <linux/module.h>
  22 #include <linux/scatterlist.h>
  23 #include <linux/slab.h>
  24
  25 struct crypto_pcbc_ctx {
  26         struct crypto_cipher *child;
  27 };
  28
  29 static int crypto_pcbc_setkey(struct crypto_tfm *parent, const u8 *key,
  30                               unsigned int keylen)
  31 {
  32         struct crypto_pcbc_ctx *ctx = crypto_tfm_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_tfm_get_flags(parent) &
  38                                 CRYPTO_TFM_REQ_MASK);
  39         err = crypto_cipher_setkey(child, key, keylen);
  40         crypto_tfm_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 blkcipher_desc *desc,
  46                                        struct blkcipher_walk *walk,
  47                                        struct crypto_cipher *tfm)
  48 {
  49         void (*fn)(struct crypto_tfm *, u8 *, const u8 *) =
  50                 crypto_cipher_alg(tfm)->cia_encrypt;
  51         int bsize = crypto_cipher_blocksize(tfm);
  52         unsigned int nbytes = walk->nbytes;
  53         u8 *src = walk->src.virt.addr;
  54         u8 *dst = walk->dst.virt.addr;
  55         u8 * const iv = walk->iv;
  56
  57         do {
  58                 crypto_xor(iv, src, bsize);
  59                 fn(crypto_cipher_tfm(tfm), dst, iv);
  60                 memcpy(iv, dst, bsize);
  61                 crypto_xor(iv, src, bsize);
  62
  63                 src += bsize;
  64                 dst += bsize;
  65         } while ((nbytes -= bsize) >= bsize);
  66
  67         return nbytes;
  68 }
  69
  70 static int crypto_pcbc_encrypt_inplace(struct blkcipher_desc *desc,
  71                                        struct blkcipher_walk *walk,
  72                                        struct crypto_cipher *tfm)
  73 {
  74         void (*fn)(struct crypto_tfm *, u8 *, const u8 *) =
  75                 crypto_cipher_alg(tfm)->cia_encrypt;
  76         int bsize = crypto_cipher_blocksize(tfm);
  77         unsigned int nbytes = walk->nbytes;
  78         u8 *src = walk->src.virt.addr;
  79         u8 * const iv = walk->iv;
  80         u8 tmpbuf[bsize];
  81
  82         do {
  83                 memcpy(tmpbuf, src, bsize);
  84                 crypto_xor(iv, src, bsize);
  85                 fn(crypto_cipher_tfm(tfm), src, iv);
  86                 memcpy(iv, tmpbuf, bsize);
  87                 crypto_xor(iv, src, bsize);
  88
  89                 src += bsize;
  90         } while ((nbytes -= bsize) >= bsize);
  91
  92         return nbytes;
  93 }
  94
  95 static int crypto_pcbc_encrypt(struct blkcipher_desc *desc,
  96                                struct scatterlist *dst, struct scatterlist *src,
  97                                unsigned int nbytes)
  98 {
  99         struct blkcipher_walk walk;
 100         struct crypto_blkcipher *tfm = desc->tfm;
 101         struct crypto_pcbc_ctx *ctx = crypto_blkcipher_ctx(tfm);
 102         struct crypto_cipher *child = ctx->child;
 103         int err;
 104
 105         blkcipher_walk_init(&walk, dst, src, nbytes);
 106         err = blkcipher_walk_virt(desc, &walk);
 107
 108         while ((nbytes = walk.nbytes)) {
 109                 if (walk.src.virt.addr == walk.dst.virt.addr)
 110                         nbytes = crypto_pcbc_encrypt_inplace(desc, &walk,
 111                                                              child);
 112                 else
 113                         nbytes = crypto_pcbc_encrypt_segment(desc, &walk,
 114                                                              child);
 115                 err = blkcipher_walk_done(desc, &walk, nbytes);
 116         }
 117
 118         return err;
 119 }
 120
 121 static int crypto_pcbc_decrypt_segment(struct blkcipher_desc *desc,
 122                                        struct blkcipher_walk *walk,
 123                                        struct crypto_cipher *tfm)
 124 {
 125         void (*fn)(struct crypto_tfm *, u8 *, const u8 *) =
 126                 crypto_cipher_alg(tfm)->cia_decrypt;
 127         int bsize = crypto_cipher_blocksize(tfm);
 128         unsigned int nbytes = walk->nbytes;
 129         u8 *src = walk->src.virt.addr;
 130         u8 *dst = walk->dst.virt.addr;
 131         u8 * const iv = walk->iv;
 132
 133         do {
 134                 fn(crypto_cipher_tfm(tfm), dst, src);
 135                 crypto_xor(dst, iv, bsize);
 136                 memcpy(iv, src, bsize);
 137                 crypto_xor(iv, dst, bsize);
 138
 139                 src += bsize;
 140                 dst += bsize;
 141         } while ((nbytes -= bsize) >= bsize);
 142
 143         return nbytes;
 144 }
 145
 146 static int crypto_pcbc_decrypt_inplace(struct blkcipher_desc *desc,
 147                                        struct blkcipher_walk *walk,
 148                                        struct crypto_cipher *tfm)
 149 {
 150         void (*fn)(struct crypto_tfm *, u8 *, const u8 *) =
 151                 crypto_cipher_alg(tfm)->cia_decrypt;
 152         int bsize = crypto_cipher_blocksize(tfm);
 153         unsigned int nbytes = walk->nbytes;
 154         u8 *src = walk->src.virt.addr;
 155         u8 * const iv = walk->iv;
 156         u8 tmpbuf[bsize];
 157
 158         do {
 159                 memcpy(tmpbuf, src, bsize);
 160                 fn(crypto_cipher_tfm(tfm), src, src);
 161                 crypto_xor(src, iv, bsize);
 162                 memcpy(iv, tmpbuf, bsize);
 163                 crypto_xor(iv, src, bsize);
 164
 165                 src += bsize;
 166         } while ((nbytes -= bsize) >= bsize);
 167
 168         return nbytes;
 169 }
 170
 171 static int crypto_pcbc_decrypt(struct blkcipher_desc *desc,
 172                                struct scatterlist *dst, struct scatterlist *src,
 173                                unsigned int nbytes)
 174 {
 175         struct blkcipher_walk walk;
 176         struct crypto_blkcipher *tfm = desc->tfm;
 177         struct crypto_pcbc_ctx *ctx = crypto_blkcipher_ctx(tfm);
 178         struct crypto_cipher *child = ctx->child;
 179         int err;
 180
 181         blkcipher_walk_init(&walk, dst, src, nbytes);
 182         err = blkcipher_walk_virt(desc, &walk);
 183
 184         while ((nbytes = walk.nbytes)) {
 185                 if (walk.src.virt.addr == walk.dst.virt.addr)
 186                         nbytes = crypto_pcbc_decrypt_inplace(desc, &walk,
 187                                                              child);
 188                 else
 189                         nbytes = crypto_pcbc_decrypt_segment(desc, &walk,
 190                                                              child);
 191                 err = blkcipher_walk_done(desc, &walk, nbytes);
 192         }
 193
 194         return err;
 195 }
 196
 197 static int crypto_pcbc_init_tfm(struct crypto_tfm *tfm)
 198 {
 199         struct crypto_instance *inst = (void *)tfm->__crt_alg;
 200         struct crypto_spawn *spawn = crypto_instance_ctx(inst);
 201         struct crypto_pcbc_ctx *ctx = crypto_tfm_ctx(tfm);
 202         struct crypto_cipher *cipher;
 203
 204         cipher = crypto_spawn_cipher(spawn);
 205         if (IS_ERR(cipher))
 206                 return PTR_ERR(cipher);
 207
 208         ctx->child = cipher;
 209         return 0;
 210 }
 211
 212 static void crypto_pcbc_exit_tfm(struct crypto_tfm *tfm)
 213 {
 214         struct crypto_pcbc_ctx *ctx = crypto_tfm_ctx(tfm);
 215         crypto_free_cipher(ctx->child);
 216 }
 217
 218 static struct crypto_instance *crypto_pcbc_alloc(struct rtattr **tb)
 219 {
 220         struct crypto_instance *inst;
 221         struct crypto_alg *alg;
 222         int err;
 223
 224         err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_BLKCIPHER);
 225         if (err)
 226                 return ERR_PTR(err);
 227
 228         alg = crypto_get_attr_alg(tb, CRYPTO_ALG_TYPE_CIPHER,
 229                                   CRYPTO_ALG_TYPE_MASK);
 230         if (IS_ERR(alg))
 231                 return ERR_CAST(alg);
 232
 233         inst = crypto_alloc_instance("pcbc", alg);
 234         if (IS_ERR(inst))
 235                 goto out_put_alg;
 236
 237         inst->alg.cra_flags = CRYPTO_ALG_TYPE_BLKCIPHER;
 238         inst->alg.cra_priority = alg->cra_priority;
 239         inst->alg.cra_blocksize = alg->cra_blocksize;
 240         inst->alg.cra_alignmask = alg->cra_alignmask;
 241         inst->alg.cra_type = &crypto_blkcipher_type;
 242
 243         /* We access the data as u32s when xoring. */
 244         inst->alg.cra_alignmask |= __alignof__(u32) - 1;
 245
 246         inst->alg.cra_blkcipher.ivsize = alg->cra_blocksize;
 247         inst->alg.cra_blkcipher.min_keysize = alg->cra_cipher.cia_min_keysize;
 248         inst->alg.cra_blkcipher.max_keysize = alg->cra_cipher.cia_max_keysize;
 249
 250         inst->alg.cra_ctxsize = sizeof(struct crypto_pcbc_ctx);
 251
 252         inst->alg.cra_init = crypto_pcbc_init_tfm;
 253         inst->alg.cra_exit = crypto_pcbc_exit_tfm;
 254
 255         inst->alg.cra_blkcipher.setkey = crypto_pcbc_setkey;
 256         inst->alg.cra_blkcipher.encrypt = crypto_pcbc_encrypt;
 257         inst->alg.cra_blkcipher.decrypt = crypto_pcbc_decrypt;
 258
 259 out_put_alg:
 260         crypto_mod_put(alg);
 261         return inst;
 262 }
 263
 264 static void crypto_pcbc_free(struct crypto_instance *inst)
 265 {
 266         crypto_drop_spawn(crypto_instance_ctx(inst));
 267         kfree(inst);
 268 }
 269
 270 static struct crypto_template crypto_pcbc_tmpl = {
 271         .name = "pcbc",
 272         .alloc = crypto_pcbc_alloc,
 273         .free = crypto_pcbc_free,
 274         .module = THIS_MODULE,
 275 };
 276
 277 static int __init crypto_pcbc_module_init(void)
 278 {
 279         return crypto_register_template(&crypto_pcbc_tmpl);
 280 }
 281
 282 static void __exit crypto_pcbc_module_exit(void)
 283 {
 284         crypto_unregister_template(&crypto_pcbc_tmpl);
 285 }
 286
 287 module_init(crypto_pcbc_module_init);
 288 module_exit(crypto_pcbc_module_exit);
 289
 290 MODULE_LICENSE("GPL");
 291 MODULE_DESCRIPTION("PCBC block cipher algorithm");
 292 MODULE_ALIAS_CRYPTO("pcbc");