/*
 * AMD Cryptographic Coprocessor (CCP) DES3 crypto API support
 *
 * Copyright (C) 2016,2017 Advanced Micro Devices, Inc.
 *
 * Author: Gary R Hook <ghook@amd.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

#include <linux/module.h>
#include <linux/sched.h>
#include <linux/delay.h>
#include <linux/scatterlist.h>
#include <linux/crypto.h>
#include <crypto/algapi.h>
#include <crypto/scatterwalk.h>
#include <crypto/des.h>

#include "ccp-crypto.h"

static int ccp_des3_complete(struct crypto_async_request *async_req, int ret)
{
        struct ablkcipher_request *req = ablkcipher_request_cast(async_req);
        struct ccp_ctx *ctx = crypto_tfm_ctx(req->base.tfm);
        struct ccp_des3_req_ctx *rctx = ablkcipher_request_ctx(req);

        if (ret)
                return ret;

        if (ctx->u.des3.mode != CCP_DES3_MODE_ECB)
                memcpy(req->info, rctx->iv, DES3_EDE_BLOCK_SIZE);

        return 0;
}

static int ccp_des3_setkey(struct crypto_ablkcipher *tfm, const u8 *key,
                unsigned int key_len)
{
        struct ccp_ctx *ctx = crypto_tfm_ctx(crypto_ablkcipher_tfm(tfm));
        struct ccp_crypto_ablkcipher_alg *alg =
                ccp_crypto_ablkcipher_alg(crypto_ablkcipher_tfm(tfm));
        u32 *flags = &tfm->base.crt_flags;


        /* From des_generic.c:
         *
         * RFC2451:
         *   If the first two or last two independent 64-bit keys are
         *   equal (k1 == k2 or k2 == k3), then the DES3 operation is simply the
         *   same as DES.  Implementers MUST reject keys that exhibit this
         *   property.
         */
        const u32 *K = (const u32 *)key;

        if (unlikely(!((K[0] ^ K[2]) | (K[1] ^ K[3])) ||
                     !((K[2] ^ K[4]) | (K[3] ^ K[5]))) &&
                     (*flags & CRYPTO_TFM_REQ_WEAK_KEY)) {
                *flags |= CRYPTO_TFM_RES_WEAK_KEY;
                return -EINVAL;
        }

        /* It's not clear that there is any support for a keysize of 112.
         * If needed, the caller should make K1 == K3
         */
        ctx->u.des3.type = CCP_DES3_TYPE_168;
        ctx->u.des3.mode = alg->mode;
        ctx->u.des3.key_len = key_len;

        memcpy(ctx->u.des3.key, key, key_len);
        sg_init_one(&ctx->u.des3.key_sg, ctx->u.des3.key, key_len);

        return 0;
}

static int ccp_des3_crypt(struct ablkcipher_request *req, bool encrypt)
{
        struct ccp_ctx *ctx = crypto_tfm_ctx(req->base.tfm);
        struct ccp_des3_req_ctx *rctx = ablkcipher_request_ctx(req);
        struct scatterlist *iv_sg = NULL;
        unsigned int iv_len = 0;
        int ret;

        if (!ctx->u.des3.key_len)
                return -EINVAL;

        if (((ctx->u.des3.mode == CCP_DES3_MODE_ECB) ||
             (ctx->u.des3.mode == CCP_DES3_MODE_CBC)) &&
            (req->nbytes & (DES3_EDE_BLOCK_SIZE - 1)))
                return -EINVAL;

        if (ctx->u.des3.mode != CCP_DES3_MODE_ECB) {
                if (!req->info)
                        return -EINVAL;

                memcpy(rctx->iv, req->info, DES3_EDE_BLOCK_SIZE);
                iv_sg = &rctx->iv_sg;
                iv_len = DES3_EDE_BLOCK_SIZE;
                sg_init_one(iv_sg, rctx->iv, iv_len);
        }

        memset(&rctx->cmd, 0, sizeof(rctx->cmd));
        INIT_LIST_HEAD(&rctx->cmd.entry);
        rctx->cmd.engine = CCP_ENGINE_DES3;
        rctx->cmd.u.des3.type = ctx->u.des3.type;
        rctx->cmd.u.des3.mode = ctx->u.des3.mode;
        rctx->cmd.u.des3.action = (encrypt)
                                  ? CCP_DES3_ACTION_ENCRYPT
                                  : CCP_DES3_ACTION_DECRYPT;
        rctx->cmd.u.des3.key = &ctx->u.des3.key_sg;
        rctx->cmd.u.des3.key_len = ctx->u.des3.key_len;
        rctx->cmd.u.des3.iv = iv_sg;
        rctx->cmd.u.des3.iv_len = iv_len;
        rctx->cmd.u.des3.src = req->src;
        rctx->cmd.u.des3.src_len = req->nbytes;
        rctx->cmd.u.des3.dst = req->dst;

        ret = ccp_crypto_enqueue_request(&req->base, &rctx->cmd);

        return ret;
}

static int ccp_des3_encrypt(struct ablkcipher_request *req)
{
        return ccp_des3_crypt(req, true);
}

static int ccp_des3_decrypt(struct ablkcipher_request *req)
{
        return ccp_des3_crypt(req, false);
}

static int ccp_des3_cra_init(struct crypto_tfm *tfm)
{
        struct ccp_ctx *ctx = crypto_tfm_ctx(tfm);

        ctx->complete = ccp_des3_complete;
        ctx->u.des3.key_len = 0;

        tfm->crt_ablkcipher.reqsize = sizeof(struct ccp_des3_req_ctx);

        return 0;
}

static void ccp_des3_cra_exit(struct crypto_tfm *tfm)
{
}

static struct crypto_alg ccp_des3_defaults = {
        .cra_flags      = CRYPTO_ALG_TYPE_ABLKCIPHER |
                CRYPTO_ALG_ASYNC |
                CRYPTO_ALG_KERN_DRIVER_ONLY |
                CRYPTO_ALG_NEED_FALLBACK,
        .cra_blocksize  = DES3_EDE_BLOCK_SIZE,
        .cra_ctxsize    = sizeof(struct ccp_ctx),
        .cra_priority   = CCP_CRA_PRIORITY,
        .cra_type       = &crypto_ablkcipher_type,
        .cra_init       = ccp_des3_cra_init,
        .cra_exit       = ccp_des3_cra_exit,
        .cra_module     = THIS_MODULE,
        .cra_ablkcipher = {
                .setkey         = ccp_des3_setkey,
                .encrypt        = ccp_des3_encrypt,
                .decrypt        = ccp_des3_decrypt,
                .min_keysize    = DES3_EDE_KEY_SIZE,
                .max_keysize    = DES3_EDE_KEY_SIZE,
        },
};

struct ccp_des3_def {
        enum ccp_des3_mode mode;
        unsigned int version;
        const char *name;
        const char *driver_name;
        unsigned int blocksize;
        unsigned int ivsize;
        struct crypto_alg *alg_defaults;
};

static struct ccp_des3_def des3_algs[] = {
        {
                .mode           = CCP_DES3_MODE_ECB,
                .version        = CCP_VERSION(5, 0),
                .name           = "ecb(des3_ede)",
                .driver_name    = "ecb-des3-ccp",
                .blocksize      = DES3_EDE_BLOCK_SIZE,
                .ivsize         = 0,
                .alg_defaults   = &ccp_des3_defaults,
        },
        {
                .mode           = CCP_DES3_MODE_CBC,
                .version        = CCP_VERSION(5, 0),
                .name           = "cbc(des3_ede)",
                .driver_name    = "cbc-des3-ccp",
                .blocksize      = DES3_EDE_BLOCK_SIZE,
                .ivsize         = DES3_EDE_BLOCK_SIZE,
                .alg_defaults   = &ccp_des3_defaults,
        },
};

static int ccp_register_des3_alg(struct list_head *head,
                                 const struct ccp_des3_def *def)
{
        struct ccp_crypto_ablkcipher_alg *ccp_alg;
        struct crypto_alg *alg;
        int ret;

        ccp_alg = kzalloc(sizeof(*ccp_alg), GFP_KERNEL);
        if (!ccp_alg)
                return -ENOMEM;

        INIT_LIST_HEAD(&ccp_alg->entry);

        ccp_alg->mode = def->mode;

        /* Copy the defaults and override as necessary */
        alg = &ccp_alg->alg;
        *alg = *def->alg_defaults;
        snprintf(alg->cra_name, CRYPTO_MAX_ALG_NAME, "%s", def->name);
        snprintf(alg->cra_driver_name, CRYPTO_MAX_ALG_NAME, "%s",
                        def->driver_name);
        alg->cra_blocksize = def->blocksize;
        alg->cra_ablkcipher.ivsize = def->ivsize;

        ret = crypto_register_alg(alg);
        if (ret) {
                pr_err("%s ablkcipher algorithm registration error (%d)\n",
                                alg->cra_name, ret);
                kfree(ccp_alg);
                return ret;
        }

        list_add(&ccp_alg->entry, head);

        return 0;
}

int ccp_register_des3_algs(struct list_head *head)
{
        int i, ret;
        unsigned int ccpversion = ccp_version();

        for (i = 0; i < ARRAY_SIZE(des3_algs); i++) {
                if (des3_algs[i].version > ccpversion)
                        continue;
                ret = ccp_register_des3_alg(head, &des3_algs[i]);
                if (ret)
                        return ret;
        }

        return 0;
}