/*
 * Glue Code for 3-way parallel assembler optimized version of Twofish
 *
 * Copyright (c) 2011 Jussi Kivilinna <jussi.kivilinna@mbnet.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 <asm/processor.h>
#include <linux/crypto.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/types.h>
#include <crypto/algapi.h>
#include <crypto/twofish.h>
#include <crypto/b128ops.h>
#include <crypto/lrw.h>
#include <crypto/xts.h>

/* regular block cipher functions from twofish_x86_64 module */
asmlinkage void twofish_enc_blk(struct twofish_ctx *ctx, u8 *dst,
                                const u8 *src);
asmlinkage void twofish_dec_blk(struct twofish_ctx *ctx, u8 *dst,
                                const u8 *src);

/* 3-way parallel cipher functions */
asmlinkage void __twofish_enc_blk_3way(struct twofish_ctx *ctx, u8 *dst,
                                       const u8 *src, bool xor);
asmlinkage void twofish_dec_blk_3way(struct twofish_ctx *ctx, u8 *dst,
                                     const u8 *src);

static inline void twofish_enc_blk_3way(struct twofish_ctx *ctx, u8 *dst,
                                        const u8 *src)
{
        __twofish_enc_blk_3way(ctx, dst, src, false);
}

static inline void twofish_enc_blk_xor_3way(struct twofish_ctx *ctx, u8 *dst,
                                            const u8 *src)
{
        __twofish_enc_blk_3way(ctx, dst, src, true);
}

static int ecb_crypt(struct blkcipher_desc *desc, struct blkcipher_walk *walk,
                     void (*fn)(struct twofish_ctx *, u8 *, const u8 *),
                     void (*fn_3way)(struct twofish_ctx *, u8 *, const u8 *))
{
        struct twofish_ctx *ctx = crypto_blkcipher_ctx(desc->tfm);
        unsigned int bsize = TF_BLOCK_SIZE;
        unsigned int nbytes;
        int err;

        err = blkcipher_walk_virt(desc, walk);

        while ((nbytes = walk->nbytes)) {
                u8 *wsrc = walk->src.virt.addr;
                u8 *wdst = walk->dst.virt.addr;

                /* Process three block batch */
                if (nbytes >= bsize * 3) {
                        do {
                                fn_3way(ctx, wdst, wsrc);

                                wsrc += bsize * 3;
                                wdst += bsize * 3;
                                nbytes -= bsize * 3;
                        } while (nbytes >= bsize * 3);

                        if (nbytes < bsize)
                                goto done;
                }

                /* Handle leftovers */
                do {
                        fn(ctx, wdst, wsrc);

                        wsrc += bsize;
                        wdst += bsize;
                        nbytes -= bsize;
                } while (nbytes >= bsize);

done:
                err = blkcipher_walk_done(desc, walk, nbytes);
        }

        return err;
}

static int ecb_encrypt(struct blkcipher_desc *desc, struct scatterlist *dst,
                       struct scatterlist *src, unsigned int nbytes)
{
        struct blkcipher_walk walk;

        blkcipher_walk_init(&walk, dst, src, nbytes);
        return ecb_crypt(desc, &walk, twofish_enc_blk, twofish_enc_blk_3way);
}

static int ecb_decrypt(struct blkcipher_desc *desc, struct scatterlist *dst,
                       struct scatterlist *src, unsigned int nbytes)
{
        struct blkcipher_walk walk;

        blkcipher_walk_init(&walk, dst, src, nbytes);
        return ecb_crypt(desc, &walk, twofish_dec_blk, twofish_dec_blk_3way);
}

static unsigned int __cbc_encrypt(struct blkcipher_desc *desc,
                                  struct blkcipher_walk *walk)
{
        struct twofish_ctx *ctx = crypto_blkcipher_ctx(desc->tfm);
        unsigned int bsize = TF_BLOCK_SIZE;
        unsigned int nbytes = walk->nbytes;
        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);
                twofish_enc_blk(ctx, (u8 *)dst, (u8 *)dst);
                iv = dst;

                src += 1;
                dst += 1;
                nbytes -= bsize;
        } while (nbytes >= bsize);

        u128_xor((u128 *)walk->iv, (u128 *)walk->iv, iv);
        return nbytes;
}

static int cbc_encrypt(struct blkcipher_desc *desc, struct scatterlist *dst,
                       struct scatterlist *src, unsigned int nbytes)
{
        struct blkcipher_walk walk;
        int err;

        blkcipher_walk_init(&walk, dst, src, nbytes);
        err = blkcipher_walk_virt(desc, &walk);

        while ((nbytes = walk.nbytes)) {
                nbytes = __cbc_encrypt(desc, &walk);
                err = blkcipher_walk_done(desc, &walk, nbytes);
        }

        return err;
}

static unsigned int __cbc_decrypt(struct blkcipher_desc *desc,
                                  struct blkcipher_walk *walk)
{
        struct twofish_ctx *ctx = crypto_blkcipher_ctx(desc->tfm);
        unsigned int bsize = TF_BLOCK_SIZE;
        unsigned int nbytes = walk->nbytes;
        u128 *src = (u128 *)walk->src.virt.addr;
        u128 *dst = (u128 *)walk->dst.virt.addr;
        u128 ivs[3 - 1];
        u128 last_iv;

        /* Start of the last block. */
        src += nbytes / bsize - 1;
        dst += nbytes / bsize - 1;

        last_iv = *src;

        /* Process three block batch */
        if (nbytes >= bsize * 3) {
                do {
                        nbytes -= bsize * (3 - 1);
                        src -= 3 - 1;
                        dst -= 3 - 1;

                        ivs[0] = src[0];
                        ivs[1] = src[1];

                        twofish_dec_blk_3way(ctx, (u8 *)dst, (u8 *)src);

                        u128_xor(dst + 1, dst + 1, ivs + 0);
                        u128_xor(dst + 2, dst + 2, ivs + 1);

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

                        u128_xor(dst, dst, src - 1);
                        src -= 1;
                        dst -= 1;
                } while (nbytes >= bsize * 3);

                if (nbytes < bsize)
                        goto done;
        }

        /* Handle leftovers */
        for (;;) {
                twofish_dec_blk(ctx, (u8 *)dst, (u8 *)src);

                nbytes -= bsize;
                if (nbytes < bsize)
                        break;

                u128_xor(dst, dst, src - 1);
                src -= 1;
                dst -= 1;
        }

done:
        u128_xor(dst, dst, (u128 *)walk->iv);
        *(u128 *)walk->iv = last_iv;

        return nbytes;
}

static int cbc_decrypt(struct blkcipher_desc *desc, struct scatterlist *dst,
                       struct scatterlist *src, unsigned int nbytes)
{
        struct blkcipher_walk walk;
        int err;

        blkcipher_walk_init(&walk, dst, src, nbytes);
        err = blkcipher_walk_virt(desc, &walk);

        while ((nbytes = walk.nbytes)) {
                nbytes = __cbc_decrypt(desc, &walk);
                err = blkcipher_walk_done(desc, &walk, nbytes);
        }

        return err;
}

static inline void u128_to_be128(be128 *dst, const u128 *src)
{
        dst->a = cpu_to_be64(src->a);
        dst->b = cpu_to_be64(src->b);
}

static inline void be128_to_u128(u128 *dst, const be128 *src)
{
        dst->a = be64_to_cpu(src->a);
        dst->b = be64_to_cpu(src->b);
}

static inline void u128_inc(u128 *i)
{
        i->b++;
        if (!i->b)
                i->a++;
}

static void ctr_crypt_final(struct blkcipher_desc *desc,
                            struct blkcipher_walk *walk)
{
        struct twofish_ctx *ctx = crypto_blkcipher_ctx(desc->tfm);
        u8 *ctrblk = walk->iv;
        u8 keystream[TF_BLOCK_SIZE];
        u8 *src = walk->src.virt.addr;
        u8 *dst = walk->dst.virt.addr;
        unsigned int nbytes = walk->nbytes;

        twofish_enc_blk(ctx, keystream, ctrblk);
        crypto_xor(keystream, src, nbytes);
        memcpy(dst, keystream, nbytes);

        crypto_inc(ctrblk, TF_BLOCK_SIZE);
}

static unsigned int __ctr_crypt(struct blkcipher_desc *desc,
                                struct blkcipher_walk *walk)
{
        struct twofish_ctx *ctx = crypto_blkcipher_ctx(desc->tfm);
        unsigned int bsize = TF_BLOCK_SIZE;
        unsigned int nbytes = walk->nbytes;
        u128 *src = (u128 *)walk->src.virt.addr;
        u128 *dst = (u128 *)walk->dst.virt.addr;
        u128 ctrblk;
        be128 ctrblocks[3];

        be128_to_u128(&ctrblk, (be128 *)walk->iv);

        /* Process three block batch */
        if (nbytes >= bsize * 3) {
                do {
                        if (dst != src) {
                                dst[0] = src[0];
                                dst[1] = src[1];
                                dst[2] = src[2];
                        }

                        /* create ctrblks for parallel encrypt */
                        u128_to_be128(&ctrblocks[0], &ctrblk);
                        u128_inc(&ctrblk);
                        u128_to_be128(&ctrblocks[1], &ctrblk);
                        u128_inc(&ctrblk);
                        u128_to_be128(&ctrblocks[2], &ctrblk);
                        u128_inc(&ctrblk);

                        twofish_enc_blk_xor_3way(ctx, (u8 *)dst,
                                                 (u8 *)ctrblocks);

                        src += 3;
                        dst += 3;
                        nbytes -= bsize * 3;
                } while (nbytes >= bsize * 3);

                if (nbytes < bsize)
                        goto done;
        }

        /* Handle leftovers */
        do {
                if (dst != src)
                        *dst = *src;

                u128_to_be128(&ctrblocks[0], &ctrblk);
                u128_inc(&ctrblk);

                twofish_enc_blk(ctx, (u8 *)ctrblocks, (u8 *)ctrblocks);
                u128_xor(dst, dst, (u128 *)ctrblocks);

                src += 1;
                dst += 1;
                nbytes -= bsize;
        } while (nbytes >= bsize);

done:
        u128_to_be128((be128 *)walk->iv, &ctrblk);
        return nbytes;
}

static int ctr_crypt(struct blkcipher_desc *desc, struct scatterlist *dst,
                     struct scatterlist *src, unsigned int nbytes)
{
        struct blkcipher_walk walk;
        int err;

        blkcipher_walk_init(&walk, dst, src, nbytes);
        err = blkcipher_walk_virt_block(desc, &walk, TF_BLOCK_SIZE);

        while ((nbytes = walk.nbytes) >= TF_BLOCK_SIZE) {
                nbytes = __ctr_crypt(desc, &walk);
                err = blkcipher_walk_done(desc, &walk, nbytes);
        }

        if (walk.nbytes) {
                ctr_crypt_final(desc, &walk);
                err = blkcipher_walk_done(desc, &walk, 0);
        }

        return err;
}

static void encrypt_callback(void *priv, u8 *srcdst, unsigned int nbytes)
{
        const unsigned int bsize = TF_BLOCK_SIZE;
        struct twofish_ctx *ctx = priv;
        int i;

        if (nbytes == 3 * bsize) {
                twofish_enc_blk_3way(ctx, srcdst, srcdst);
                return;
        }

        for (i = 0; i < nbytes / bsize; i++, srcdst += bsize)
                twofish_enc_blk(ctx, srcdst, srcdst);
}

static void decrypt_callback(void *priv, u8 *srcdst, unsigned int nbytes)
{
        const unsigned int bsize = TF_BLOCK_SIZE;
        struct twofish_ctx *ctx = priv;
        int i;

        if (nbytes == 3 * bsize) {
                twofish_dec_blk_3way(ctx, srcdst, srcdst);
                return;
        }

        for (i = 0; i < nbytes / bsize; i++, srcdst += bsize)
                twofish_dec_blk(ctx, srcdst, srcdst);
}

struct twofish_lrw_ctx {
        struct lrw_table_ctx lrw_table;
        struct twofish_ctx twofish_ctx;
};

static int lrw_twofish_setkey(struct crypto_tfm *tfm, const u8 *key,
                              unsigned int keylen)
{
        struct twofish_lrw_ctx *ctx = crypto_tfm_ctx(tfm);
        int err;

        err = __twofish_setkey(&ctx->twofish_ctx, key, keylen - TF_BLOCK_SIZE,
                               &tfm->crt_flags);
        if (err)
                return err;

        return lrw_init_table(&ctx->lrw_table, key + keylen - TF_BLOCK_SIZE);
}

static int lrw_encrypt(struct blkcipher_desc *desc, struct scatterlist *dst,
                       struct scatterlist *src, unsigned int nbytes)
{
        struct twofish_lrw_ctx *ctx = crypto_blkcipher_ctx(desc->tfm);
        be128 buf[3];
        struct lrw_crypt_req req = {
                .tbuf = buf,
                .tbuflen = sizeof(buf),

                .table_ctx = &ctx->lrw_table,
                .crypt_ctx = &ctx->twofish_ctx,
                .crypt_fn = encrypt_callback,
        };

        return lrw_crypt(desc, dst, src, nbytes, &req);
}

static int lrw_decrypt(struct blkcipher_desc *desc, struct scatterlist *dst,
                       struct scatterlist *src, unsigned int nbytes)
{
        struct twofish_lrw_ctx *ctx = crypto_blkcipher_ctx(desc->tfm);
        be128 buf[3];
        struct lrw_crypt_req req = {
                .tbuf = buf,
                .tbuflen = sizeof(buf),

                .table_ctx = &ctx->lrw_table,
                .crypt_ctx = &ctx->twofish_ctx,
                .crypt_fn = decrypt_callback,
        };

        return lrw_crypt(desc, dst, src, nbytes, &req);
}

static void lrw_exit_tfm(struct crypto_tfm *tfm)
{
        struct twofish_lrw_ctx *ctx = crypto_tfm_ctx(tfm);

        lrw_free_table(&ctx->lrw_table);
}

struct twofish_xts_ctx {
        struct twofish_ctx tweak_ctx;
        struct twofish_ctx crypt_ctx;
};

static int xts_twofish_setkey(struct crypto_tfm *tfm, const u8 *key,
                              unsigned int keylen)
{
        struct twofish_xts_ctx *ctx = crypto_tfm_ctx(tfm);
        u32 *flags = &tfm->crt_flags;
        int err;

        /* key consists of keys of equal size concatenated, therefore
         * the length must be even
         */
        if (keylen % 2) {
                *flags |= CRYPTO_TFM_RES_BAD_KEY_LEN;
                return -EINVAL;
        }

        /* first half of xts-key is for crypt */
        err = __twofish_setkey(&ctx->crypt_ctx, key, keylen / 2, flags);
        if (err)
                return err;

        /* second half of xts-key is for tweak */
        return __twofish_setkey(&ctx->tweak_ctx, key + keylen / 2, keylen / 2,
                                flags);
}

static int xts_encrypt(struct blkcipher_desc *desc, struct scatterlist *dst,
                       struct scatterlist *src, unsigned int nbytes)
{
        struct twofish_xts_ctx *ctx = crypto_blkcipher_ctx(desc->tfm);
        be128 buf[3];
        struct xts_crypt_req req = {
                .tbuf = buf,
                .tbuflen = sizeof(buf),

                .tweak_ctx = &ctx->tweak_ctx,
                .tweak_fn = XTS_TWEAK_CAST(twofish_enc_blk),
                .crypt_ctx = &ctx->crypt_ctx,
                .crypt_fn = encrypt_callback,
        };

        return xts_crypt(desc, dst, src, nbytes, &req);
}

static int xts_decrypt(struct blkcipher_desc *desc, struct scatterlist *dst,
                       struct scatterlist *src, unsigned int nbytes)
{
        struct twofish_xts_ctx *ctx = crypto_blkcipher_ctx(desc->tfm);
        be128 buf[3];
        struct xts_crypt_req req = {
                .tbuf = buf,
                .tbuflen = sizeof(buf),

                .tweak_ctx = &ctx->tweak_ctx,
                .tweak_fn = XTS_TWEAK_CAST(twofish_enc_blk),
                .crypt_ctx = &ctx->crypt_ctx,
                .crypt_fn = decrypt_callback,
        };

        return xts_crypt(desc, dst, src, nbytes, &req);
}

static struct crypto_alg tf_algs[5] = { {
        .cra_name               = "ecb(twofish)",
        .cra_driver_name        = "ecb-twofish-3way",
        .cra_priority           = 300,
        .cra_flags              = CRYPTO_ALG_TYPE_BLKCIPHER,
        .cra_blocksize          = TF_BLOCK_SIZE,
        .cra_ctxsize            = sizeof(struct twofish_ctx),
        .cra_alignmask          = 0,
        .cra_type               = &crypto_blkcipher_type,
        .cra_module             = THIS_MODULE,
        .cra_list               = LIST_HEAD_INIT(tf_algs[0].cra_list),
        .cra_u = {
                .blkcipher = {
                        .min_keysize    = TF_MIN_KEY_SIZE,
                        .max_keysize    = TF_MAX_KEY_SIZE,
                        .setkey         = twofish_setkey,
                        .encrypt        = ecb_encrypt,
                        .decrypt        = ecb_decrypt,
                },
        },
}, {
        .cra_name               = "cbc(twofish)",
        .cra_driver_name        = "cbc-twofish-3way",
        .cra_priority           = 300,
        .cra_flags              = CRYPTO_ALG_TYPE_BLKCIPHER,
        .cra_blocksize          = TF_BLOCK_SIZE,
        .cra_ctxsize            = sizeof(struct twofish_ctx),
        .cra_alignmask          = 0,
        .cra_type               = &crypto_blkcipher_type,
        .cra_module             = THIS_MODULE,
        .cra_list               = LIST_HEAD_INIT(tf_algs[1].cra_list),
        .cra_u = {
                .blkcipher = {
                        .min_keysize    = TF_MIN_KEY_SIZE,
                        .max_keysize    = TF_MAX_KEY_SIZE,
                        .ivsize         = TF_BLOCK_SIZE,
                        .setkey         = twofish_setkey,
                        .encrypt        = cbc_encrypt,
                        .decrypt        = cbc_decrypt,
                },
        },
}, {
        .cra_name               = "ctr(twofish)",
        .cra_driver_name        = "ctr-twofish-3way",
        .cra_priority           = 300,
        .cra_flags              = CRYPTO_ALG_TYPE_BLKCIPHER,
        .cra_blocksize          = 1,
        .cra_ctxsize            = sizeof(struct twofish_ctx),
        .cra_alignmask          = 0,
        .cra_type               = &crypto_blkcipher_type,
        .cra_module             = THIS_MODULE,
        .cra_list               = LIST_HEAD_INIT(tf_algs[2].cra_list),
        .cra_u = {
                .blkcipher = {
                        .min_keysize    = TF_MIN_KEY_SIZE,
                        .max_keysize    = TF_MAX_KEY_SIZE,
                        .ivsize         = TF_BLOCK_SIZE,
                        .setkey         = twofish_setkey,
                        .encrypt        = ctr_crypt,
                        .decrypt        = ctr_crypt,
                },
        },
}, {
        .cra_name               = "lrw(twofish)",
        .cra_driver_name        = "lrw-twofish-3way",
        .cra_priority           = 300,
        .cra_flags              = CRYPTO_ALG_TYPE_BLKCIPHER,
        .cra_blocksize          = TF_BLOCK_SIZE,
        .cra_ctxsize            = sizeof(struct twofish_lrw_ctx),
        .cra_alignmask          = 0,
        .cra_type               = &crypto_blkcipher_type,
        .cra_module             = THIS_MODULE,
        .cra_list               = LIST_HEAD_INIT(tf_algs[3].cra_list),
        .cra_exit               = lrw_exit_tfm,
        .cra_u = {
                .blkcipher = {
                        .min_keysize    = TF_MIN_KEY_SIZE + TF_BLOCK_SIZE,
                        .max_keysize    = TF_MAX_KEY_SIZE + TF_BLOCK_SIZE,
                        .ivsize         = TF_BLOCK_SIZE,
                        .setkey         = lrw_twofish_setkey,
                        .encrypt        = lrw_encrypt,
                        .decrypt        = lrw_decrypt,
                },
        },
}, {
        .cra_name               = "xts(twofish)",
        .cra_driver_name        = "xts-twofish-3way",
        .cra_priority           = 300,
        .cra_flags              = CRYPTO_ALG_TYPE_BLKCIPHER,
        .cra_blocksize          = TF_BLOCK_SIZE,
        .cra_ctxsize            = sizeof(struct twofish_xts_ctx),
        .cra_alignmask          = 0,
        .cra_type               = &crypto_blkcipher_type,
        .cra_module             = THIS_MODULE,
        .cra_list               = LIST_HEAD_INIT(tf_algs[4].cra_list),
        .cra_u = {
                .blkcipher = {
                        .min_keysize    = TF_MIN_KEY_SIZE * 2,
                        .max_keysize    = TF_MAX_KEY_SIZE * 2,
                        .ivsize         = TF_BLOCK_SIZE,
                        .setkey         = xts_twofish_setkey,
                        .encrypt        = xts_encrypt,
                        .decrypt        = xts_decrypt,
                },
        },
} };

static bool is_blacklisted_cpu(void)
{
        if (boot_cpu_data.x86_vendor != X86_VENDOR_INTEL)
                return false;

        if (boot_cpu_data.x86 == 0x06 &&
                (boot_cpu_data.x86_model == 0x1c ||
                 boot_cpu_data.x86_model == 0x26 ||
                 boot_cpu_data.x86_model == 0x36)) {
                /*
                 * On Atom, twofish-3way is slower than original assembler
                 * implementation. Twofish-3way trades off some performance in
                 * storing blocks in 64bit registers to allow three blocks to
                 * be processed parallel. Parallel operation then allows gaining
                 * more performance than was trade off, on out-of-order CPUs.
                 * However Atom does not benefit from this parallellism and
                 * should be blacklisted.
                 */
                return true;
        }

        if (boot_cpu_data.x86 == 0x0f) {
                /*
                 * On Pentium 4, twofish-3way is slower than original assembler
                 * implementation because excessive uses of 64bit rotate and
                 * left-shifts (which are really slow on P4) needed to store and
                 * handle 128bit block in two 64bit registers.
                 */
                return true;
        }

        return false;
}

static int force;
module_param(force, int, 0);
MODULE_PARM_DESC(force, "Force module load, ignore CPU blacklist");

static int __init init(void)
{
        if (!force && is_blacklisted_cpu()) {
                printk(KERN_INFO
                        "twofish-x86_64-3way: performance on this CPU "
                        "would be suboptimal: disabling "
                        "twofish-x86_64-3way.\n");
                return -ENODEV;
        }

        return crypto_register_algs(tf_algs, ARRAY_SIZE(tf_algs));
}

static void __exit fini(void)
{
        crypto_unregister_algs(tf_algs, ARRAY_SIZE(tf_algs));
}

module_init(init);
module_exit(fini);

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Twofish Cipher Algorithm, 3-way parallel asm optimized");
MODULE_ALIAS("twofish");
MODULE_ALIAS("twofish-asm");