/*
 * AMD Cryptographic Coprocessor (CCP) DES3 crypto API support
 *
 * Copyright (C) 2016 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;
}