path: root/crypto/ahash.c

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Asynchronous Cryptographic Hash operations.
 *
 * This is the implementation of the ahash (asynchronous hash) API.  It differs
 * from shash (synchronous hash) in that ahash supports asynchronous operations,
 * and it hashes data from scatterlists instead of virtually addressed buffers.
 *
 * The ahash API provides access to both ahash and shash algorithms.  The shash
 * API only provides access to shash algorithms.
 *
 * Copyright (c) 2008 Loc Ho <lho@amcc.com>
 */

#include <crypto/scatterwalk.h>
#include <linux/cryptouser.h>
#include <linux/err.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/seq_file.h>
#include <linux/string.h>
#include <linux/string_choices.h>
#include <net/netlink.h>

#include "hash.h"

#define CRYPTO_ALG_TYPE_AHASH_MASK	0x0000000e

struct crypto_hash_walk {
	const char *data;

	unsigned int offset;
	unsigned int flags;

	struct page *pg;
	unsigned int entrylen;

	unsigned int total;
	struct scatterlist *sg;
};

struct ahash_save_req_state {
	struct list_head head;
	struct ahash_request *req0;
	struct ahash_request *cur;
	int (*op)(struct ahash_request *req);
	crypto_completion_t compl;
	void *data;
	struct scatterlist sg;
	const u8 *src;
	u8 *page;
	unsigned int offset;
	unsigned int nbytes;
};

static void ahash_reqchain_done(void *data, int err);
static int ahash_save_req(struct ahash_request *req, crypto_completion_t cplt);
static void ahash_restore_req(struct ahash_request *req);
static void ahash_def_finup_done1(void *data, int err);
static int ahash_def_finup_finish1(struct ahash_request *req, int err);
static int ahash_def_finup(struct ahash_request *req);

static int hash_walk_next(struct crypto_hash_walk *walk)
{
	unsigned int offset = walk->offset;
	unsigned int nbytes = min(walk->entrylen,
				  ((unsigned int)(PAGE_SIZE)) - offset);

	walk->data = kmap_local_page(walk->pg);
	walk->data += offset;
	walk->entrylen -= nbytes;
	return nbytes;
}

static int hash_walk_new_entry(struct crypto_hash_walk *walk)
{
	struct scatterlist *sg;

	sg = walk->sg;
	walk->offset = sg->offset;
	walk->pg = nth_page(sg_page(walk->sg), (walk->offset >> PAGE_SHIFT));
	walk->offset = offset_in_page(walk->offset);
	walk->entrylen = sg->length;

	if (walk->entrylen > walk->total)
		walk->entrylen = walk->total;
	walk->total -= walk->entrylen;

	return hash_walk_next(walk);
}

static int crypto_hash_walk_first(struct ahash_request *req,
				  struct crypto_hash_walk *walk)
{
	walk->total = req->nbytes;
	walk->entrylen = 0;

	if (!walk->total)
		return 0;

	walk->flags = req->base.flags;

	if (ahash_request_isvirt(req)) {
		walk->data = req->svirt;
		walk->total = 0;
		return req->nbytes;
	}

	walk->sg = req->src;

	return hash_walk_new_entry(walk);
}

static int crypto_hash_walk_done(struct crypto_hash_walk *walk, int err)
{
	if ((walk->flags & CRYPTO_AHASH_REQ_VIRT))
		return err;

	walk->data -= walk->offset;

	kunmap_local(walk->data);
	crypto_yield(walk->flags);

	if (err)
		return err;

	if (walk->entrylen) {
		walk->offset = 0;
		walk->pg++;
		return hash_walk_next(walk);
	}

	if (!walk->total)
		return 0;

	walk->sg = sg_next(walk->sg);

	return hash_walk_new_entry(walk);
}

static inline int crypto_hash_walk_last(struct crypto_hash_walk *walk)
{
	return !(walk->entrylen | walk->total);
}

/*
 * For an ahash tfm that is using an shash algorithm (instead of an ahash
 * algorithm), this returns the underlying shash tfm.
 */
static inline struct crypto_shash *ahash_to_shash(struct crypto_ahash *tfm)
{
	return *(struct crypto_shash **)crypto_ahash_ctx(tfm);
}

static inline struct shash_desc *prepare_shash_desc(struct ahash_request *req,
						    struct crypto_ahash *tfm)
{
	struct shash_desc *desc = ahash_request_ctx(req);

	desc->tfm = ahash_to_shash(tfm);
	return desc;
}

int shash_ahash_update(struct ahash_request *req, struct shash_desc *desc)
{
	struct crypto_hash_walk walk;
	int nbytes;

	for (nbytes = crypto_hash_walk_first(req, &walk); nbytes > 0;
	     nbytes