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digest.c

/*
 * Cryptographic API.
 *
 * Digest operations.
 *
 * Copyright (c) 2002 James Morris <jmorris@intercode.com.au>
 *
 * 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.
 *
 */

#include <linux/mm.h>
#include <linux/errno.h>
#include <linux/hardirq.h>
#include <linux/highmem.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/scatterlist.h>

#include "internal.h"
#include "scatterwalk.h"

static int init(struct hash_desc *desc)
{
      struct crypto_tfm *tfm = crypto_hash_tfm(desc->tfm);

      tfm->__crt_alg->cra_digest.dia_init(tfm);
      return 0;
}

static int update2(struct hash_desc *desc,
               struct scatterlist *sg, unsigned int nbytes)
{
      struct crypto_tfm *tfm = crypto_hash_tfm(desc->tfm);
      unsigned int alignmask = crypto_tfm_alg_alignmask(tfm);

      if (!nbytes)
            return 0;

      for (;;) {
            struct page *pg = sg_page(sg);
            unsigned int offset = sg->offset;
            unsigned int l = sg->length;

            if (unlikely(l > nbytes))
                  l = nbytes;
            nbytes -= l;

            do {
                  unsigned int bytes_from_page = min(l, ((unsigned int)
                                             (PAGE_SIZE)) - 
                                             offset);
                  char *src = crypto_kmap(pg, 0);
                  char *p = src + offset;

                  if (unlikely(offset & alignmask)) {
                        unsigned int bytes =
                              alignmask + 1 - (offset & alignmask);
                        bytes = min(bytes, bytes_from_page);
                        tfm->__crt_alg->cra_digest.dia_update(tfm, p,
                                                      bytes);
                        p += bytes;
                        bytes_from_page -= bytes;
                        l -= bytes;
                  }
                  tfm->__crt_alg->cra_digest.dia_update(tfm, p,
                                                bytes_from_page);
                  crypto_kunmap(src, 0);
                  crypto_yield(desc->flags);
                  offset = 0;
                  pg++;
                  l -= bytes_from_page;
            } while (l > 0);

            if (!nbytes)
                  break;
            sg = scatterwalk_sg_next(sg);
      }

      return 0;
}

static int update(struct hash_desc *desc,
              struct scatterlist *sg, unsigned int nbytes)
{
      if (WARN_ON_ONCE(in_irq()))
            return -EDEADLK;
      return update2(desc, sg, nbytes);
}

static int final(struct hash_desc *desc, u8 *out)
{
      struct crypto_tfm *tfm = crypto_hash_tfm(desc->tfm);
      unsigned long alignmask = crypto_tfm_alg_alignmask(tfm);
      struct digest_alg *digest = &tfm->__crt_alg->cra_digest;

      if (unlikely((unsigned long)out & alignmask)) {
            unsigned long align = alignmask + 1;
            unsigned long addr = (unsigned long)crypto_tfm_ctx(tfm);
            u8 *dst = (u8 *)ALIGN(addr, align) +
                    ALIGN(tfm->__crt_alg->cra_ctxsize, align);

            digest->dia_final(tfm, dst);
            memcpy(out, dst, digest->dia_digestsize);
      } else
            digest->dia_final(tfm, out);

      return 0;
}

static int nosetkey(struct crypto_hash *tfm, const u8 *key, unsigned int keylen)
{
      crypto_hash_clear_flags(tfm, CRYPTO_TFM_RES_MASK);
      return -ENOSYS;
}

static int setkey(struct crypto_hash *hash, const u8 *key, unsigned int keylen)
{
      struct crypto_tfm *tfm = crypto_hash_tfm(hash);

      crypto_hash_clear_flags(hash, CRYPTO_TFM_RES_MASK);
      return tfm->__crt_alg->cra_digest.dia_setkey(tfm, key, keylen);
}

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

      init(desc);
      update2(desc, sg, nbytes);
      return final(desc, out);
}

int crypto_init_digest_ops(struct crypto_tfm *tfm)
{
      struct hash_tfm *ops = &tfm->crt_hash;
      struct digest_alg *dalg = &tfm->__crt_alg->cra_digest;

      if (dalg->dia_digestsize > crypto_tfm_alg_blocksize(tfm))
            return -EINVAL;
      
      ops->init   = init;
      ops->update = update;
      ops->final  = final;
      ops->digest = digest;
      ops->setkey = dalg->dia_setkey ? setkey : nosetkey;
      ops->digestsize   = dalg->dia_digestsize;
      
      return 0;
}

void crypto_exit_digest_ops(struct crypto_tfm *tfm)
{
}

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