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         void (*xor)(u8 *dst, const u8 *src, unsigned int bs);
  28 };
  29
  30 static int crypto_pcbc_setkey(struct crypto_tfm *parent, const u8 *key,
  31                               unsigned int keylen)
  32 {
  33         struct crypto_pcbc_ctx *ctx = crypto_tfm_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_tfm_get_flags(parent) &
  39                                 CRYPTO_TFM_REQ_MASK);
  40         err = crypto_cipher_setkey(child, key, keylen);
  41         crypto_tfm_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 blkcipher_desc *desc,
  47                                        struct blkcipher_walk *walk,
  48                                        struct crypto_cipher *tfm,
  49                                        void (*xor)(u8 *, const u8 *,
  50                                                    unsigned int))
  51 {
  52         void (*fn)(struct crypto_tfm *, u8 *, const u8 *) =
  53                 crypto_cipher_alg(tfm)->cia_encrypt;
  54         int bsize = crypto_cipher_blocksize(tfm);
  55         unsigned int nbytes = walk->nbytes;
  56         u8 *src = walk->src.virt.addr;
  57         u8 *dst = walk->dst.virt.addr;
  58         u8 *iv = walk->iv;
  59
  60         do {
  61                 xor(iv, src, bsize);
  62                 fn(crypto_cipher_tfm(tfm), dst, iv);
  63                 memcpy(iv, dst, bsize);
  64                 xor(iv, src, bsize);
  65
  66                 src += bsize;
  67                 dst += bsize;
  68         } while ((nbytes -= bsize) >= bsize);
  69
  70         return nbytes;
  71 }
  72
  73 static int crypto_pcbc_encrypt_inplace(struct blkcipher_desc *desc,
  74                                        struct blkcipher_walk *walk,
  75                                        struct crypto_cipher *tfm,
  76                                        void (*xor)(u8 *, const u8 *,
  77                                                    unsigned int))
  78 {
  79         void (*fn)(struct crypto_tfm *, u8 *, const u8 *) =
  80                 crypto_cipher_alg(tfm)->cia_encrypt;
  81         int bsize = crypto_cipher_blocksize(tfm);
  82         unsigned int nbytes = walk->nbytes;
  83         u8 *src = walk->src.virt.addr;
  84         u8 *iv = walk->iv;
  85         u8 tmpbuf[bsize];
  86
  87         do {
  88                 memcpy(tmpbuf, src, bsize);
  89                 xor(iv, tmpbuf, bsize);
  90                 fn(crypto_cipher_tfm(tfm), src, iv);
  91                 memcpy(iv, src, bsize);
  92                 xor(iv, tmpbuf, bsize);
  93
  94                 src += bsize;
  95         } while ((nbytes -= bsize) >= bsize);
  96
  97         memcpy(walk->iv, iv, bsize);
  98
  99         return nbytes;
 100 }
 101
 102 static int crypto_pcbc_encrypt(struct blkcipher_desc *desc,
 103                                struct scatterlist *dst, struct scatterlist *src,
 104                                unsigned int nbytes)
 105 {
 106         struct blkcipher_walk walk;
 107         struct crypto_blkcipher *tfm = desc->tfm;
 108         struct crypto_pcbc_ctx *ctx = crypto_blkcipher_ctx(tfm);
 109         struct crypto_cipher *child = ctx->child;
 110         void (*xor)(u8 *, const u8 *, unsigned int bs) = ctx->xor;
 111         int err;
 112
 113         blkcipher_walk_init(&walk, dst, src, nbytes);
 114         err = blkcipher_walk_virt(desc, &walk);
 115
 116         while ((nbytes = walk.nbytes)) {
 117                 if (walk.src.virt.addr == walk.dst.virt.addr)
 118                         nbytes = crypto_pcbc_encrypt_inplace(desc, &walk, child,
 119                                                              xor);
 120                 else
 121                         nbytes = crypto_pcbc_encrypt_segment(desc, &walk, child,
 122                                                              xor);
 123                 err = blkcipher_walk_done(desc, &walk, nbytes);
 124         }
 125
 126         return err;
 127 }
 128
 129 static int crypto_pcbc_decrypt_segment(struct blkcipher_desc *desc,
 130                                        struct blkcipher_walk *walk,
 131                                        struct crypto_cipher *tfm,
 132                                        void (*xor)(u8 *, const u8 *,
 133                                                    unsigned int))
 134 {
 135         void (*fn)(struct crypto_tfm *, u8 *, const u8 *) =
 136                 crypto_cipher_alg(tfm)->cia_decrypt;
 137         int bsize = crypto_cipher_blocksize(tfm);
 138         unsigned int nbytes = walk->nbytes;
 139         u8 *src = walk->src.virt.addr;
 140         u8 *dst = walk->dst.virt.addr;
 141         u8 *iv = walk->iv;
 142
 143         do {
 144                 fn(crypto_cipher_tfm(tfm), dst, src);
 145                 xor(dst, iv, bsize);
 146                 memcpy(iv, src, bsize);
 147                 xor(iv, dst, bsize);
 148
 149                 src += bsize;
 150                 dst += bsize;
 151         } while ((nbytes -= bsize) >= bsize);
 152
 153         memcpy(walk->iv, iv, bsize);
 154
 155         return nbytes;
 156 }
 157
 158 static int crypto_pcbc_decrypt_inplace(struct blkcipher_desc *desc,
 159                                        struct blkcipher_walk *walk,
 160                                        struct crypto_cipher *tfm,
 161                                        void (*xor)(u8 *, const u8 *,
 162                                                    unsigned int))
 163 {
 164         void (*fn)(struct crypto_tfm *, u8 *, const u8 *) =
 165                 crypto_cipher_alg(tfm)->cia_decrypt;
 166         int bsize = crypto_cipher_blocksize(tfm);
 167         unsigned int nbytes = walk->nbytes;
 168         u8 *src = walk->src.virt.addr;
 169         u8 *iv = walk->iv;
 170         u8 tmpbuf[bsize];
 171
 172         do {
 173                 memcpy(tmpbuf, src, bsize);
 174                 fn(crypto_cipher_tfm(tfm), src, src);
 175                 xor(src, iv, bsize);
 176                 memcpy(iv, tmpbuf, bsize);
 177                 xor(iv, src, bsize);
 178
 179                 src += bsize;
 180         } while ((nbytes -= bsize) >= bsize);
 181
 182         memcpy(walk->iv, iv, bsize);
 183
 184         return nbytes;
 185 }
 186
 187 static int crypto_pcbc_decrypt(struct blkcipher_desc *desc,
 188                                struct scatterlist *dst, struct scatterlist *src,
 189                                unsigned int nbytes)
 190 {
 191         struct blkcipher_walk walk;
 192         struct crypto_blkcipher *tfm = desc->tfm;
 193         struct crypto_pcbc_ctx *ctx = crypto_blkcipher_ctx(tfm);
 194         struct crypto_cipher *child = ctx->child;
 195         void (*xor)(u8 *, const u8 *, unsigned int bs) = ctx->xor;
 196         int err;
 197
 198         blkcipher_walk_init(&walk, dst, src, nbytes);
 199         err = blkcipher_walk_virt(desc, &walk);
 200
 201         while ((nbytes = walk.nbytes)) {
 202                 if (walk.src.virt.addr == walk.dst.virt.addr)
 203                         nbytes = crypto_pcbc_decrypt_inplace(desc, &walk, child,
 204                                                              xor);
 205                 else
 206                         nbytes = crypto_pcbc_decrypt_segment(desc, &walk, child,
 207                                                              xor);
 208                 err = blkcipher_walk_done(desc, &walk, nbytes);
 209         }
 210
 211         return err;
 212 }
 213
 214 static void xor_byte(u8 *a, const u8 *b, unsigned int bs)
 215 {
 216         do {
 217                 *a++ ^= *b++;
 218         } while (--bs);
 219 }
 220
 221 static void xor_quad(u8 *dst, const u8 *src, unsigned int bs)
 222 {
 223         u32 *a = (u32 *)dst;
 224         u32 *b = (u32 *)src;
 225
 226         do {
 227                 *a++ ^= *b++;
 228         } while ((bs -= 4));
 229 }
 230
 231 static void xor_64(u8 *a, const u8 *b, unsigned int bs)
 232 {
 233         ((u32 *)a)[0] ^= ((u32 *)b)[0];
 234         ((u32 *)a)[1] ^= ((u32 *)b)[1];
 235 }
 236
 237 static void xor_128(u8 *a, const u8 *b, unsigned int bs)
 238 {
 239         ((u32 *)a)[0] ^= ((u32 *)b)[0];
 240         ((u32 *)a)[1] ^= ((u32 *)b)[1];
 241         ((u32 *)a)[2] ^= ((u32 *)b)[2];
 242         ((u32 *)a)[3] ^= ((u32 *)b)[3];
 243 }
 244
 245 static int crypto_pcbc_init_tfm(struct crypto_tfm *tfm)
 246 {
 247         struct crypto_instance *inst = (void *)tfm->__crt_alg;
 248         struct crypto_spawn *spawn = crypto_instance_ctx(inst);
 249         struct crypto_pcbc_ctx *ctx = crypto_tfm_ctx(tfm);
 250         struct crypto_cipher *cipher;
 251
 252         switch (crypto_tfm_alg_blocksize(tfm)) {
 253         case 8:
 254                 ctx->xor = xor_64;
 255                 break;
 256
 257         case 16:
 258                 ctx->xor = xor_128;
 259                 break;
 260
 261         default:
 262                 if (crypto_tfm_alg_blocksize(tfm) % 4)
 263                         ctx->xor = xor_byte;
 264                 else
 265                         ctx->xor = xor_quad;
 266         }
 267
 268         cipher = crypto_spawn_cipher(spawn);
 269         if (IS_ERR(cipher))
 270                 return PTR_ERR(cipher);
 271
 272         ctx->child = cipher;
 273         return 0;
 274 }
 275
 276 static void crypto_pcbc_exit_tfm(struct crypto_tfm *tfm)
 277 {
 278         struct crypto_pcbc_ctx *ctx = crypto_tfm_ctx(tfm);
 279         crypto_free_cipher(ctx->child);
 280 }
 281
 282 static struct crypto_instance *crypto_pcbc_alloc(void *param, unsigned int len)
 283 {
 284         struct crypto_instance *inst;
 285         struct crypto_alg *alg;
 286
 287         alg = crypto_get_attr_alg(param, len, CRYPTO_ALG_TYPE_CIPHER,
 288                                   CRYPTO_ALG_TYPE_MASK | CRYPTO_ALG_ASYNC);
 289         if (IS_ERR(alg))
 290                 return ERR_PTR(PTR_ERR(alg));
 291
 292         inst = crypto_alloc_instance("pcbc", alg);
 293         if (IS_ERR(inst))
 294                 goto out_put_alg;
 295
 296         inst->alg.cra_flags = CRYPTO_ALG_TYPE_BLKCIPHER;
 297         inst->alg.cra_priority = alg->cra_priority;
 298         inst->alg.cra_blocksize = alg->cra_blocksize;
 299         inst->alg.cra_alignmask = alg->cra_alignmask;
 300         inst->alg.cra_type = &crypto_blkcipher_type;
 301
 302         if (!(alg->cra_blocksize % 4))
 303                 inst->alg.cra_alignmask |= 3;
 304         inst->alg.cra_blkcipher.ivsize = alg->cra_blocksize;
 305         inst->alg.cra_blkcipher.min_keysize = alg->cra_cipher.cia_min_keysize;
 306         inst->alg.cra_blkcipher.max_keysize = alg->cra_cipher.cia_max_keysize;
 307
 308         inst->alg.cra_ctxsize = sizeof(struct crypto_pcbc_ctx);
 309
 310         inst->alg.cra_init = crypto_pcbc_init_tfm;
 311         inst->alg.cra_exit = crypto_pcbc_exit_tfm;
 312
 313         inst->alg.cra_blkcipher.setkey = crypto_pcbc_setkey;
 314         inst->alg.cra_blkcipher.encrypt = crypto_pcbc_encrypt;
 315         inst->alg.cra_blkcipher.decrypt = crypto_pcbc_decrypt;
 316
 317 out_put_alg:
 318         crypto_mod_put(alg);
 319         return inst;
 320 }
 321
 322 static void crypto_pcbc_free(struct crypto_instance *inst)
 323 {
 324         crypto_drop_spawn(crypto_instance_ctx(inst));
 325         kfree(inst);
 326 }
 327
 328 static struct crypto_template crypto_pcbc_tmpl = {
 329         .name = "pcbc",
 330         .alloc = crypto_pcbc_alloc,
 331         .free = crypto_pcbc_free,
 332         .module = THIS_MODULE,
 333 };
 334
 335 static int __init crypto_pcbc_module_init(void)
 336 {
 337         return crypto_register_template(&crypto_pcbc_tmpl);
 338 }
 339
 340 static void __exit crypto_pcbc_module_exit(void)
 341 {
 342         crypto_unregister_template(&crypto_pcbc_tmpl);
 343 }
 344
 345 module_init(crypto_pcbc_module_init);
 346 module_exit(crypto_pcbc_module_exit);
 347
 348 MODULE_LICENSE("GPL");
 349 MODULE_DESCRIPTION("PCBC block cipher algorithm");