/*
 * Shared glue code for 128bit block ciphers
 *
 * Copyright © 2012-2013 Jussi Kivilinna <jussi.kivilinna@iki.fi>
 *
 * CBC & ECB parts based on code (crypto/cbc.c,ecb.c) by:
 *   Copyright (c) 2006 Herbert Xu <herbert@gondor.apana.org.au>
 * CTR part based on code (crypto/ctr.c) by:
 *   (C) Copyright IBM Corp. 2007 - Joy Latten <latten@us.ibm.com>
 *
 * 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
 *
 */

#include <linux/module.h>
#include <crypto/b128ops.h>
#include <crypto/gf128mul.h>
#include <crypto/internal/skcipher.h>
#include <crypto/xts.h>
#include <asm/crypto/glue_helper.h>

int glue_ecb_req_128bit(const struct common_glue_ctx *gctx,
			struct skcipher_request *req)
{
	void *ctx = crypto_skcipher_ctx(crypto_skcipher_reqtfm(req));
	const unsigned int bsize = 128 / 8;
	struct skcipher_walk walk;
	bool fpu_enabled = false;
	unsigned int nbytes;
	int err;

	err = skcipher_walk_virt(&walk, req, false);

	while ((nbytes = walk.nbytes)) {
		const u8 *src = walk.src.virt.addr;
		u8 *dst = walk.dst.virt.addr;
		unsigned int func_bytes;
		unsigned int i;

		fpu_enabled = glue_fpu_begin(bsize, gctx->fpu_blocks_limit,
					     &walk, fpu_enabled, nbytes);
		for (i = 0; i < gctx->num_funcs; i++) {
			func_bytes = bsize * gctx->funcs[i].num_blocks;

			if (nbytes < func_bytes)
				continue;

			/* Process multi-block batch */
			do {
				gctx->funcs[i].fn_u.ecb(ctx, dst, src);
				src += func_bytes;
				dst += func_bytes;
				nbytes -= func_bytes;
			} while (nbytes >= func_bytes);

			if (nbytes < bsize)
				break;
		}
		err = skcipher_walk_done(&walk, nbytes);
	}

	glue_fpu_end(fpu_enabled);
	return err;
}
EXPORT_SYMBOL_GPL(glue_ecb_req_128bit);

int glue_cbc_encrypt_req_128bit(const common_glue_func_t fn,
				struct skcipher_request *req)
{
	void *ctx = crypto_skcipher_ctx(crypto_skcipher_reqtfm(req));
	const unsigned int bsize = 128 / 8;
	struct skcipher_walk walk;
	unsigned int nbytes;
	int err;

	err = skcipher_walk_virt(&walk, req, false);

	while ((nbytes = walk.nbytes)) {
		const u128 *src = (u128 *)walk.src.virt.addr;
		u128 *dst = (u128 *)walk.dst.virt.addr;
		u128 *iv = (u128 *)walk.iv;

		do {
			u128_xor(dst, src, iv);
			fn(ctx, (u8 *)dst, (u8 *)dst);
			iv = dst;
			src++;
			dst++;
			nbytes -= bsize;
		} while (nbytes >= bsize);

		*(u128 *)walk.iv = *iv;
		err = skcipher_walk_done(&walk, nbytes);
	}
	return err;
}
EXPORT_SYMBOL_GPL(glue_cbc_encrypt_req_128bit);

int glue_cbc_decrypt_req_128bit(const struct common_glue_ctx *gctx,
				struct skcipher_request *req)
{
	void *ctx = crypto_skcipher_ctx(crypto_skcipher_reqtfm(req));
	const unsigned int bsize = 128 / 8;
	struct skcipher_walk walk;
	bool fpu_enabled = false;
	unsigned int nbytes;
	int err;

	err = skcipher_walk_virt(&walk, req, false);

	while ((nbytes = walk.nbytes)) {
		const u128 *src = walk.src.virt.addr;
		u128 *dst = walk.dst.virt.addr;
		unsigned int func_bytes, num_blocks;
		unsigned int i;
		u128 last_iv;

		fpu_enabled = glue_fpu_begin(bsize, gctx->fpu_blocks_limit,
					     &walk, fpu_enabled, nbytes);
		/* Start of the last block. */
		src += nbytes / bsize - 1;
		dst += nbytes / bsize - 1;

		last_iv = *src;

		for (i = 0; i < gctx->num_funcs; i++) {
			num_blocks = gctx->funcs[i].num_blocks;
			func_bytes = bsize * num_blocks;

			if (nbytes < func_bytes)
				continue;

			/* Process multi-block batch */
			do {
				src -= num_blocks - 1;
				dst -= num_blocks - 1;

				gctx->funcs[i].fn_u.cbc(ctx, dst, src);

				nbytes -= func_bytes;
				if (nbytes < bsize)
					goto done;

				u128_xor(dst, dst, --src);
				dst--;
			} while (nbytes >= func_bytes);
		}
done:
		u128_xor(dst, dst, (u128 *)walk.iv);
		*(u128 *)walk.iv = last_iv;
		err = skcipher_walk_done(&walk, nbytes);
	}

	glue_fpu_end(fpu_enabled);
	return err;
}
EXPORT_SYMBOL_GPL(glue_cbc_decrypt_req_128bit);

int glue_ctr_req_128bit(const struct common_glue_ctx *gctx,
			struct skcipher_request *req)
{
	void *ctx = crypto_skcipher_ctx(crypto_skcipher_reqtfm(req));
	const unsigned int bsize = 128 / 8;
	struct skcipher_walk walk;
	bool fpu_enabled = false;
	unsigned int nbytes;
	int err;

	err = skcipher_walk_virt(&walk, req, false);

	while ((nbytes = walk.nbytes) >= bsize) {
		const u128 *src = walk.src.virt.addr;
		u128 *dst = walk.dst.virt.addr;
		unsigned int func_bytes, num_blocks;
		unsigned int i;
		le128 ctrblk;

		fpu_enabled = glue_fpu_begin(bsize, gctx->fpu_blocks_limit,
					     &walk, fpu_enabled, nbytes);

		be128_to_le128(&ctrblk, (be128 *)walk.iv);

		for (i = 0; i < gctx->num_funcs; i++) {
			num_blocks = gctx->funcs[i].num_blocks;
			func_bytes = bsize * num_blocks;

			if (nbytes < func_bytes)
				continue;

			/* Process multi-block batch */
			do {
				gctx->funcs[i].fn_u.ctr(ctx, dst, src, &ctrblk);
				src += num_blocks;
				dst += num_blocks;
				nbytes -= func_bytes;
			} while (nbytes >= func_bytes);

			if (nbytes < bsize)
				break;
		}

		le128_to_be128((be128 *)walk.iv, &ctrblk);
		err = skcipher_walk_done(&walk, nbytes);
	}

	glue_fpu_end(fpu_enabled);

	if (nbytes) {
		le128 ctrblk;
		u128 tmp;

		be128_to_le128(&ctrblk, (be128 *)walk.iv);
		memcpy(&tmp, walk.src.virt.addr, nbytes);
		gctx->funcs[gctx->num_funcs - 1].fn_u.ctr(ctx, &tmp, &tmp,
							  &ctrblk);
		memcpy(walk.dst.virt.addr, &tmp, nbytes);
		le128_to_be128((be128 *)walk.iv, &ctrblk);

		err = skcipher_walk_done(&walk, 0);
	}

	return err;
}
EXPORT_SYMBOL_GPL(glue_ctr_req_128bit);

static unsigned int __glue_xts_req_128bit(const struct common_glue_ctx *gctx,
					  void *ctx,
					  struct skcipher_walk *walk)
{
	const unsigned int bsize = 128 / 8;
	unsigned int nbytes = walk->nbytes;
	u128 *src = walk->src.virt.addr;
	u128 *dst = walk->dst.virt.addr;
	unsigned int num_blocks, func_bytes;
	unsigned int i;

	/* Process multi-block batch */
	for (i = 0; i < gctx->num_funcs; i++) {
		num_blocks = gctx->funcs[i].num_blocks;
		func_bytes = bsize * num_blocks;

		if (nbytes >= func_bytes) {
			do {
				gctx->funcs[i].fn_u.xts(ctx, dst, src,
							walk->iv);

				src += num_blocks;
				dst += num_blocks;
				nbytes -= func_bytes;
			} while (nbytes >= func_bytes);

			if (nbytes < bsize)
				goto done;
		}
	}

done:
	return nbytes;
}

int glue_xts_req_128bit(const struct common_glue_ctx *gctx,
			struct skcipher_request *req,
			common_glue_func_t tweak_fn, void *tweak_ctx,
			void *crypt_ctx)
{
	const unsigned int bsize = 128 / 8;
	struct skcipher_walk walk;
	bool fpu_enabled = false;
	unsigned int nbytes;
	int err;

	err = skcipher_walk_virt(&walk, req, false);
	nbytes = walk.nbytes;
	if (!nbytes)
		return err;

	/* set minimum length to bsize, for tweak_fn */
	fpu_enabled = glue_fpu_begin(bsize, gctx->fpu_blocks_limit,
				     &walk, fpu_enabled,
				     nbytes < bsize ? bsize : nbytes);

	/* calculate first value of T */
	tweak_fn(tweak_ctx, walk.iv, walk.iv);

	while (nbytes) {
		nbytes = __glue_xts_req_128bit(gctx, crypt_ctx, &walk);

		err = skcipher_walk_done(&walk, nbytes);
		nbytes = walk.nbytes;
	}

	glue_fpu_end(fpu_enabled);

	return err;
}
EXPORT_SYMBOL_GPL(glue_xts_req_128bit);

void glue_xts_crypt_128bit_one(void *ctx, u128 *dst, const u128 *src, le128 *iv,
			       common_glue_func_t fn)
{
	le128 ivblk = *iv;

	/* generate next IV */
	gf128mul_x_ble(iv, &ivblk);

	/* CC <- T xor C */
	u128_xor(dst, src, (u128 *)&ivblk);

	/* PP <- D(Key2,CC) */
	fn(ctx, (u8 *)dst, (u8 *)dst);

	/* P <- T xor PP */
	u128_xor(dst, dst, (u128 *)&ivblk);
}
EXPORT_SYMBOL_GPL(glue_xts_crypt_128bit_one);

MODULE_LICENSE("GPL");