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xcbc.c

/*
 * Copyright (C)2006 USAGI/WIDE Project
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 * Author:
 *    Kazunori Miyazawa <miyazawa@linux-ipv6.org>
 */

#include <linux/crypto.h>
#include <linux/err.h>
#include <linux/hardirq.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/rtnetlink.h>
#include <linux/slab.h>
#include <linux/scatterlist.h>
#include "internal.h"

static u_int32_t ks[12] = {0x01010101, 0x01010101, 0x01010101, 0x01010101,
                     0x02020202, 0x02020202, 0x02020202, 0x02020202,
                     0x03030303, 0x03030303, 0x03030303, 0x03030303};
/*
 * +------------------------
 * | <parent tfm>
 * +------------------------
 * | crypto_xcbc_ctx
 * +------------------------
 * | odds (block size)
 * +------------------------
 * | prev (block size)
 * +------------------------
 * | key (block size)
 * +------------------------
 * | consts (block size * 3)
 * +------------------------
 */
struct crypto_xcbc_ctx {
      struct crypto_cipher *child;
      u8 *odds;
      u8 *prev;
      u8 *key;
      u8 *consts;
      void (*xor)(u8 *a, const u8 *b, unsigned int bs);
      unsigned int keylen;
      unsigned int len;
};

static void xor_128(u8 *a, const u8 *b, unsigned int bs)
{
      ((u32 *)a)[0] ^= ((u32 *)b)[0];
      ((u32 *)a)[1] ^= ((u32 *)b)[1];
      ((u32 *)a)[2] ^= ((u32 *)b)[2];
      ((u32 *)a)[3] ^= ((u32 *)b)[3];
}

static int _crypto_xcbc_digest_setkey(struct crypto_hash *parent,
                              struct crypto_xcbc_ctx *ctx)
{
      int bs = crypto_hash_blocksize(parent);
      int err = 0;
      u8 key1[bs];

      if ((err = crypto_cipher_setkey(ctx->child, ctx->key, ctx->keylen)))
          return err;

      crypto_cipher_encrypt_one(ctx->child, key1, ctx->consts);

      return crypto_cipher_setkey(ctx->child, key1, bs);
}

static int crypto_xcbc_digest_setkey(struct crypto_hash *parent,
                             const u8 *inkey, unsigned int keylen)
{
      struct crypto_xcbc_ctx *ctx = crypto_hash_ctx_aligned(parent);

      if (keylen != crypto_cipher_blocksize(ctx->child))
            return -EINVAL;

      ctx->keylen = keylen;
      memcpy(ctx->key, inkey, keylen);
      ctx->consts = (u8*)ks;

      return _crypto_xcbc_digest_setkey(parent, ctx);
}

static int crypto_xcbc_digest_init(struct hash_desc *pdesc)
{
      struct crypto_xcbc_ctx *ctx = crypto_hash_ctx_aligned(pdesc->tfm);
      int bs = crypto_hash_blocksize(pdesc->tfm);

      ctx->len = 0;
      memset(ctx->odds, 0, bs);
      memset(ctx->prev, 0, bs);

      return 0;
}

static int crypto_xcbc_digest_update2(struct hash_desc *pdesc,
                              struct scatterlist *sg,
                              unsigned int nbytes)
{
      struct crypto_hash *parent = pdesc->tfm;
      struct crypto_xcbc_ctx *ctx = crypto_hash_ctx_aligned(parent);
      struct crypto_cipher *tfm = ctx->child;
      int bs = crypto_hash_blocksize(parent);
      unsigned int i = 0;

      do {

            struct page *pg = sg_page(&sg[i]);
            unsigned int offset = sg[i].offset;
            unsigned int slen = sg[i].length;

            while (slen > 0) {
                  unsigned int len = min(slen, ((unsigned int)(PAGE_SIZE)) - offset);
                  char *p = crypto_kmap(pg, 0) + offset;

                  /* checking the data can fill the block */
                  if ((ctx->len + len) <= bs) {
                        memcpy(ctx->odds + ctx->len, p, len);
                        ctx->len += len;
                        slen -= len;

                        /* checking the rest of the page */
                        if (len + offset >= PAGE_SIZE) {
                              offset = 0;
                              pg++;
                        } else
                              offset += len;

                        crypto_kunmap(p, 0);
                        crypto_yield(pdesc->flags);
                        continue;
                  }

                  /* filling odds with new data and encrypting it */
                  memcpy(ctx->odds + ctx->len, p, bs - ctx->len);
                  len -= bs - ctx->len;
                  p += bs - ctx->len;

                  ctx->xor(ctx->prev, ctx->odds, bs);
                  crypto_cipher_encrypt_one(tfm, ctx->prev, ctx->prev);

                  /* clearing the length */
                  ctx->len = 0;

                  /* encrypting the rest of data */
                  while (len > bs) {
                        ctx->xor(ctx->prev, p, bs);
                        crypto_cipher_encrypt_one(tfm, ctx->prev,
                                            ctx->prev);
                        p += bs;
                        len -= bs;
                  }

                  /* keeping the surplus of blocksize */
                  if (len) {
                        memcpy(ctx->odds, p, len);
                        ctx->len = len;
                  }
                  crypto_kunmap(p, 0);
                  crypto_yield(pdesc->flags);
                  slen -= min(slen, ((unsigned int)(PAGE_SIZE)) - offset);
                  offset = 0;
                  pg++;
            }
            nbytes-=sg[i].length;
            i++;
      } while (nbytes>0);

      return 0;
}

static int crypto_xcbc_digest_update(struct hash_desc *pdesc,
                             struct scatterlist *sg,
                             unsigned int nbytes)
{
      if (WARN_ON_ONCE(in_irq()))
            return -EDEADLK;
      return crypto_xcbc_digest_update2(pdesc, sg, nbytes);
}

static int crypto_xcbc_digest_final(struct hash_desc *pdesc, u8 *out)
{
      struct crypto_hash *parent = pdesc->tfm;
      struct crypto_xcbc_ctx *ctx = crypto_hash_ctx_aligned(parent);
      struct crypto_cipher *tfm = ctx->child;
      int bs = crypto_hash_blocksize(parent);
      int err = 0;

      if (ctx->len == bs) {
            u8 key2[bs];

            if ((err = crypto_cipher_setkey(tfm, ctx->key, ctx->keylen)) != 0)
                  return err;

            crypto_cipher_encrypt_one(tfm, key2,
                                (u8 *)(ctx->consts + bs));

            ctx->xor(ctx->prev, ctx->odds, bs);
            ctx->xor(ctx->prev, key2, bs);
            _crypto_xcbc_digest_setkey(parent, ctx);

            crypto_cipher_encrypt_one(tfm, out, ctx->prev);
      } else {
            u8 key3[bs];
            unsigned int rlen;
            u8 *p = ctx->odds + ctx->len;
            *p = 0x80;
            p++;

            rlen = bs - ctx->len -1;
            if (rlen)
                  memset(p, 0, rlen);

            if ((err = crypto_cipher_setkey(tfm, ctx->key, ctx->keylen)) != 0)
                  return err;

            crypto_cipher_encrypt_one(tfm, key3,
                                (u8 *)(ctx->consts + bs * 2));

            ctx->xor(ctx->prev, ctx->odds, bs);
            ctx->xor(ctx->prev, key3, bs);

            _crypto_xcbc_digest_setkey(parent, ctx);

            crypto_cipher_encrypt_one(tfm, out, ctx->prev);
      }

      return 0;
}

static int crypto_xcbc_digest(struct hash_desc *pdesc,
              struct scatterlist *sg, unsigned int nbytes, u8 *out)
{
      if (WARN_ON_ONCE(in_irq()))
            return -EDEADLK;

      crypto_xcbc_digest_init(pdesc);
      crypto_xcbc_digest_update2(pdesc, sg, nbytes);
      return crypto_xcbc_digest_final(pdesc, out);
}

static int xcbc_init_tfm(struct crypto_tfm *tfm)
{
      struct crypto_cipher *cipher;
      struct crypto_instance *inst = (void *)tfm->__crt_alg;
      struct crypto_spawn *spawn = crypto_instance_ctx(inst);
      struct crypto_xcbc_ctx *ctx = crypto_hash_ctx_aligned(__crypto_hash_cast(tfm));
      int bs = crypto_hash_blocksize(__crypto_hash_cast(tfm));

      cipher = crypto_spawn_cipher(spawn);
      if (IS_ERR(cipher))
            return PTR_ERR(cipher);

      switch(bs) {
      case 16:
            ctx->xor = xor_128;
            break;
      default:
            return -EINVAL;
      }

      ctx->child = cipher;
      ctx->odds = (u8*)(ctx+1);
      ctx->prev = ctx->odds + bs;
      ctx->key = ctx->prev + bs;

      return 0;
};

static void xcbc_exit_tfm(struct crypto_tfm *tfm)
{
      struct crypto_xcbc_ctx *ctx = crypto_hash_ctx_aligned(__crypto_hash_cast(tfm));
      crypto_free_cipher(ctx->child);
}

static struct crypto_instance *xcbc_alloc(struct rtattr **tb)
{
      struct crypto_instance *inst;
      struct crypto_alg *alg;
      int err;

      err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_HASH);
      if (err)
            return ERR_PTR(err);

      alg = crypto_get_attr_alg(tb, CRYPTO_ALG_TYPE_CIPHER,
                          CRYPTO_ALG_TYPE_MASK);
      if (IS_ERR(alg))
            return ERR_PTR(PTR_ERR(alg));

      switch(alg->cra_blocksize) {
      case 16:
            break;
      default:
            return ERR_PTR(PTR_ERR(alg));
      }

      inst = crypto_alloc_instance("xcbc", alg);
      if (IS_ERR(inst))
            goto out_put_alg;

      inst->alg.cra_flags = CRYPTO_ALG_TYPE_HASH;
      inst->alg.cra_priority = alg->cra_priority;
      inst->alg.cra_blocksize = alg->cra_blocksize;
      inst->alg.cra_alignmask = alg->cra_alignmask;
      inst->alg.cra_type = &crypto_hash_type;

      inst->alg.cra_hash.digestsize =
            (alg->cra_flags & CRYPTO_ALG_TYPE_MASK) ==
            CRYPTO_ALG_TYPE_HASH ? alg->cra_hash.digestsize :
                               alg->cra_blocksize;
      inst->alg.cra_ctxsize = sizeof(struct crypto_xcbc_ctx) +
                        ALIGN(inst->alg.cra_blocksize * 3, sizeof(void *));
      inst->alg.cra_init = xcbc_init_tfm;
      inst->alg.cra_exit = xcbc_exit_tfm;

      inst->alg.cra_hash.init = crypto_xcbc_digest_init;
      inst->alg.cra_hash.update = crypto_xcbc_digest_update;
      inst->alg.cra_hash.final = crypto_xcbc_digest_final;
      inst->alg.cra_hash.digest = crypto_xcbc_digest;
      inst->alg.cra_hash.setkey = crypto_xcbc_digest_setkey;

out_put_alg:
      crypto_mod_put(alg);
      return inst;
}

static void xcbc_free(struct crypto_instance *inst)
{
      crypto_drop_spawn(crypto_instance_ctx(inst));
      kfree(inst);
}

static struct crypto_template crypto_xcbc_tmpl = {
      .name = "xcbc",
      .alloc = xcbc_alloc,
      .free = xcbc_free,
      .module = THIS_MODULE,
};

static int __init crypto_xcbc_module_init(void)
{
      return crypto_register_template(&crypto_xcbc_tmpl);
}

static void __exit crypto_xcbc_module_exit(void)
{
      crypto_unregister_template(&crypto_xcbc_tmpl);
}

module_init(crypto_xcbc_module_init);
module_exit(crypto_xcbc_module_exit);

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("XCBC keyed hash algorithm");

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