// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Glue Code for assembler optimized version of 3DES
 *
 * Copyright © 2014 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>
 */

#include <crypto/algapi.h>
#include <crypto/des.h>
#include <crypto/internal/skcipher.h>
#include <linux/crypto.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/types.h>

struct des3_ede_x86_ctx {
        struct des3_ede_ctx enc;
        struct des3_ede_ctx dec;
};

/* regular block cipher functions */
asmlinkage void des3_ede_x86_64_crypt_blk(const u32 *expkey, u8 *dst,
                                          const u8 *src);

/* 3-way parallel cipher functions */
asmlinkage void des3_ede_x86_64_crypt_blk_3way(const u32 *expkey, u8 *dst,
                                               const u8 *src);

static inline void des3_ede_enc_blk(struct des3_ede_x86_ctx *ctx, u8 *dst,
                                    const u8 *src)
{
        u32 *enc_ctx = ctx->enc.expkey;

        des3_ede_x86_64_crypt_blk(enc_ctx, dst, src);
}

static inline void des3_ede_dec_blk(struct des3_ede_x86_ctx *ctx, u8 *dst,
                                    const u8 *src)
{
        u32 *dec_ctx = ctx->dec.expkey;

        des3_ede_x86_64_crypt_blk(dec_ctx, dst, src);
}

static inline void des3_ede_dec_blk_3way(struct des3_ede_x86_ctx *ctx, u8 *dst,
                                         const u8 *src)
{
        u32 *dec_ctx = ctx->dec.expkey;

        des3_ede_x86_64_crypt_blk_3way(dec_ctx, dst, src);
}

static void des3_ede_x86_encrypt(struct crypto_tfm *tfm, u8 *dst, const u8 *src)
{
        des3_ede_enc_blk(crypto_tfm_ctx(tfm), dst, src);
}

static void des3_ede_x86_decrypt(struct crypto_tfm *tfm, u8 *dst, const u8 *src)
{
        des3_ede_dec_blk(crypto_tfm_ctx(tfm), dst, src);
}

static int ecb_crypt(struct skcipher_request *req, const u32 *expkey)
{
        const unsigned int bsize = DES3_EDE_BLOCK_SIZE;
        struct skcipher_walk walk;
        unsigned int nbytes;
        int err;

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

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

                /* Process four block batch */
                if (nbytes >= bsize * 3) {
                        do {
                                des3_ede_x86_64_crypt_blk_3way(expkey, wdst,
                                                               wsrc);

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

                        if (nbytes < bsize)
                                goto done;
                }

                /* Handle leftovers */
                do {
                        des3_ede_x86_64_crypt_blk(expkey, wdst, wsrc);

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

done:
                err = skcipher_walk_done(&walk, nbytes);
        }

        return err;
}

static int ecb_encrypt(struct skcipher_request *req)
{
        struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
        struct des3_ede_x86_ctx *ctx = crypto_skcipher_ctx(tfm);

        return ecb_crypt(req, ctx->enc.expkey);
}

static int ecb_decrypt(struct skcipher_request *req)
{
        struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
        struct des3_ede_x86_ctx *ctx = crypto_skcipher_ctx(tfm);

        return ecb_crypt(req, ctx->dec.expkey);
}

static unsigned int __cbc_encrypt(struct des3_ede_x86_ctx *ctx,
                                  struct skcipher_walk *walk)
{
        unsigned int bsize = DES3_EDE_BLOCK_SIZE;
        unsigned int nbytes = walk->nbytes;
        u64 *src = (u64 *)walk->src.virt.addr;
        u64 *dst = (u64 *)walk->dst.virt.addr;
        u64 *iv = (u64 *)walk->iv;

        do {
                *dst = *src ^ *iv;
                des3_ede_enc_blk(ctx, (u8 *)dst, (u8 *)dst);
                iv = dst;

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

        *(u64 *)walk->iv = *iv;
        return nbytes;
}

static int cbc_encrypt(struct skcipher_request *req)
{
        struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
        struct des3_ede_x86_ctx *ctx = crypto_skcipher_ctx(tfm);
        struct skcipher_walk walk;
        unsigned int nbytes;
        int err;

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

        while (walk.nbytes) {
                nbytes = __cbc_encrypt(ctx, &walk);
                err = skcipher_walk_done(&walk, nbytes);
        }

        return err;
}

static unsigned int __cbc_decrypt(struct des3_ede_x86_ctx *ctx,
                                  struct skcipher_walk *walk)
{
        unsigned int bsize = DES3_EDE_BLOCK_SIZE;
        unsigned int nbytes = walk->nbytes;
        u64 *src = (u64 *)walk->src.virt.addr;
        u64 *dst = (u64 *)walk->dst.virt.addr;
        u64 ivs[3 - 1];
        u64 last_iv;

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

        last_iv = *src;

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

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

                        des3_ede_dec_blk_3way(ctx, (u8 *)dst, (u8 *)src);

                        dst[1] ^= ivs[0];
                        dst[2] ^= ivs[1];

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

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

        /* Handle leftovers */
        for (;;) {
                des3_ede_dec_blk(ctx, (u8 *)dst, (u8 *)src);

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

                *dst ^= *(src - 1);
                src -= 1;
                dst -= 1;
        }

done:
        *dst ^= *(u64 *)walk->iv;
        *(u64 *)walk->iv = last_iv;

        return nbytes;
}

static int cbc_decrypt(struct skcipher_request *req)
{
        struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
        struct des3_ede_x86_ctx *ctx = crypto_skcipher_ctx(tfm);
        struct skcipher_walk walk;
        unsigned int nbytes;
        int err;

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

        while (walk.nbytes) {
                nbytes = __cbc_decrypt(ctx, &walk);
                err = skcipher_walk_done(&walk, nbytes);
        }

        return err;
}

static int des3_ede_x86_setkey(struct crypto_tfm *tfm, const u8 *key,
                               unsigned int keylen)
{
        struct des3_ede_x86_ctx *ctx = crypto_tfm_ctx(tfm);
        u32 i, j, tmp;
        int err;

        err = des3_ede_expand_key(&ctx->enc, key, keylen);
        if (err == -ENOKEY) {
                if (crypto_tfm_get_flags(tfm) & CRYPTO_TFM_REQ_FORBID_WEAK_KEYS)
                        err = -EINVAL;
                else
                        err = 0;
        }

        if (err) {
                memset(ctx, 0, sizeof(*ctx));
                return err;
        }

        /* Fix encryption context for this implementation and form decryption
         * context. */
        j = DES3_EDE_EXPKEY_WORDS - 2;
        for (i = 0; i < DES3_EDE_EXPKEY_WORDS; i += 2, j -= 2) {
                tmp = ror32(ctx->enc.expkey[i + 1], 4);
                ctx->enc.expkey[i + 1] = tmp;

                ctx->dec.expkey[j + 0] = ctx->enc.expkey[i + 0];
                ctx->dec.expkey[j + 1] = tmp;
        }

        return 0;
}

static int des3_ede_x86_setkey_skcipher(struct crypto_skcipher *tfm,
                                        const u8 *key,
                                        unsigned int keylen)
{
        return des3_ede_x86_setkey(&tfm->base, key, keylen);
}

static struct crypto_alg des3_ede_cipher = {
        .cra_name               = "des3_ede",
        .cra_driver_name        = "des3_ede-asm",
        .cra_priority           = 200,
        .cra_flags              = CRYPTO_ALG_TYPE_CIPHER,
        .cra_blocksize          = DES3_EDE_BLOCK_SIZE,
        .cra_ctxsize            = sizeof(struct des3_ede_x86_ctx),
        .cra_module             = THIS_MODULE,
        .cra_u = {
                .cipher = {
                        .cia_min_keysize        = DES3_EDE_KEY_SIZE,
                        .cia_max_keysize        = DES3_EDE_KEY_SIZE,
                        .cia_setkey             = des3_ede_x86_setkey,
                        .cia_encrypt            = des3_ede_x86_encrypt,
                        .cia_decrypt            = des3_ede_x86_decrypt,
                }
        }
};

static struct skcipher_alg des3_ede_skciphers[] = {
        {
                .base.cra_name          = "ecb(des3_ede)",
                .base.cra_driver_name   = "ecb-des3_ede-asm",
                .base.cra_priority      = 300,
                .base.cra_blocksize     = DES3_EDE_BLOCK_SIZE,
                .base.cra_ctxsize       = sizeof(struct des3_ede_x86_ctx),
                .base.cra_module        = THIS_MODULE,
                .min_keysize            = DES3_EDE_KEY_SIZE,
                .max_keysize            = DES3_EDE_KEY_SIZE,
                .setkey                 = des3_ede_x86_setkey_skcipher,
                .encrypt                = ecb_encrypt,
                .decrypt                = ecb_decrypt,
        }, {
                .base.cra_name          = "cbc(des3_ede)",
                .base.cra_driver_name   = "cbc-des3_ede-asm",
                .base.cra_priority      = 300,
                .base.cra_blocksize     = DES3_EDE_BLOCK_SIZE,
                .base.cra_ctxsize       = sizeof(struct des3_ede_x86_ctx),
                .base.cra_module        = THIS_MODULE,
                .min_keysize            = DES3_EDE_KEY_SIZE,
                .max_keysize            = DES3_EDE_KEY_SIZE,
                .ivsize                 = DES3_EDE_BLOCK_SIZE,
                .setkey                 = des3_ede_x86_setkey_skcipher,
                .encrypt                = cbc_encrypt,
                .decrypt                = cbc_decrypt,
        }
};

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

        if (boot_cpu_data.x86 == 0x0f) {
                /*
                 * On Pentium 4, des3_ede-x86_64 is slower than generic C
                 * implementation because use of 64bit rotates (which are really
                 * slow on P4). Therefore blacklist P4s.
                 */
                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 des3_ede_x86_init(void)
{
        int err;

        if (!force && is_blacklisted_cpu()) {
                pr_info("des3_ede-x86_64: performance on this CPU would be suboptimal: disabling des3_ede-x86_64.\n");
                return -ENODEV;
        }

        err = crypto_register_alg(&des3_ede_cipher);
        if (err)
                return err;

        err = crypto_register_skciphers(des3_ede_skciphers,
                                        ARRAY_SIZE(des3_ede_skciphers));
        if (err)
                crypto_unregister_alg(&des3_ede_cipher);

        return err;
}

static void __exit des3_ede_x86_fini(void)
{
        crypto_unregister_alg(&des3_ede_cipher);
        crypto_unregister_skciphers(des3_ede_skciphers,
                                    ARRAY_SIZE(des3_ede_skciphers));
}

module_init(des3_ede_x86_init);
module_exit(des3_ede_x86_fini);

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Triple DES EDE Cipher Algorithm, asm optimized");
MODULE_ALIAS_CRYPTO("des3_ede");
MODULE_ALIAS_CRYPTO("des3_ede-asm");
MODULE_AUTHOR("Jussi Kivilinna <jussi.kivilinna@iki.fi>");