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crypto: hash - Added scatter list walking helper

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This patch adds the walking helpers for hash algorithms akin to
those of block ciphers.  This is a necessary step before we can
reimplement existing hash algorithms using the new ahash interface.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This commit is contained in:
Herbert Xu 2008-07-07 22:19:53 +08:00
parent b8454eebe3
commit 20036252fc
2 changed files with 131 additions and 1 deletions
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91
crypto/ahash.c
View file

@ -13,7 +13,8 @@
*
*/
#include <crypto/algapi.h>
#include <crypto/internal/hash.h>
#include <crypto/scatterwalk.h>
#include <linux/err.h>
#include <linux/kernel.h>
#include <linux/module.h>
@ -23,6 +24,94 @@
#include "internal.h"
static int hash_walk_next(struct crypto_hash_walk *walk)
{
unsigned int alignmask = walk->alignmask;
unsigned int offset = walk->offset;
unsigned int nbytes = min(walk->entrylen,
((unsigned int)(PAGE_SIZE)) - offset);
walk->data = crypto_kmap(walk->pg, 0);
walk->data += offset;
if (offset & alignmask)
nbytes = alignmask + 1 - (offset & alignmask);
walk->entrylen -= nbytes;
return nbytes;
}
static int hash_walk_new_entry(struct crypto_hash_walk *walk)
{
struct scatterlist *sg;
sg = walk->sg;
walk->pg = sg_page(sg);
walk->offset = sg->offset;
walk->entrylen = sg->length;
if (walk->entrylen > walk->total)
walk->entrylen = walk->total;
walk->total -= walk->entrylen;
return hash_walk_next(walk);
}
int crypto_hash_walk_done(struct crypto_hash_walk *walk, int err)
{
unsigned int alignmask = walk->alignmask;
unsigned int nbytes = walk->entrylen;
walk->data -= walk->offset;
if (nbytes && walk->offset & alignmask && !err) {
walk->offset += alignmask - 1;
walk->offset = ALIGN(walk->offset, alignmask + 1);
walk->data += walk->offset;
nbytes = min(nbytes,
((unsigned int)(PAGE_SIZE)) - walk->offset);
walk->entrylen -= nbytes;
return nbytes;
}
crypto_kunmap(walk->data, 0);
crypto_yield(walk->flags);
if (err)
return err;
walk->offset = 0;
if (nbytes)
return hash_walk_next(walk);
if (!walk->total)
return 0;
walk->sg = scatterwalk_sg_next(walk->sg);
return hash_walk_new_entry(walk);
}
EXPORT_SYMBOL_GPL(crypto_hash_walk_done);
int crypto_hash_walk_first(struct ahash_request *req,
struct crypto_hash_walk *walk)
{
walk->total = req->nbytes;
if (!walk->total)
return 0;
walk->alignmask = crypto_ahash_alignmask(crypto_ahash_reqtfm(req));
walk->sg = req->src;
walk->flags = req->base.flags;
return hash_walk_new_entry(walk);
}
EXPORT_SYMBOL_GPL(crypto_hash_walk_first);
static int ahash_setkey_unaligned(struct crypto_ahash *tfm, const u8 *key,
unsigned int keylen)
{

41
include/crypto/internal/hash.h Normal file
View file

@ -0,0 +1,41 @@
/*
* Hash algorithms.
*
* Copyright (c) 2008 Herbert Xu <herbert@gondor.apana.org.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.
*
*/
#ifndef _CRYPTO_INTERNAL_HASH_H
#define _CRYPTO_INTERNAL_HASH_H
#include <crypto/algapi.h>
struct ahash_request;
struct scatterlist;
struct crypto_hash_walk {
char *data;
unsigned int offset;
unsigned int alignmask;
struct page *pg;
unsigned int entrylen;
unsigned int total;
struct scatterlist *sg;
unsigned int flags;
};
int crypto_hash_walk_done(struct crypto_hash_walk *walk, int err);
int crypto_hash_walk_first(struct ahash_request *req,
struct crypto_hash_walk *walk);
#endif /* _CRYPTO_INTERNAL_HASH_H */