/*
   * AMD Cryptographic Coprocessor (CCP) AES XTS crypto API support
   *
   * Copyright (C) 2013 Advanced Micro Devices, Inc.
   *
   * Author: Tom Lendacky <thomas.lendacky@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/aes.h>
  #include <crypto/scatterwalk.h>
  
  #include "ccp-crypto.h"
  
  
  struct ccp_aes_xts_def {
  	const char *name;
  	const char *drv_name;
  };
  
  static struct ccp_aes_xts_def aes_xts_algs[] = {
  	{
  		.name		= "xts(aes)",
  		.drv_name	= "xts-aes-ccp",
  	},
  };
  
  struct ccp_unit_size_map {
  	unsigned int size;
  	u32 value;
  };
  
  static struct ccp_unit_size_map unit_size_map[] = {
  	{
  		.size	= 4096,
  		.value	= CCP_XTS_AES_UNIT_SIZE_4096,
  	},
  	{
  		.size	= 2048,
  		.value	= CCP_XTS_AES_UNIT_SIZE_2048,
  	},
  	{
  		.size	= 1024,
  		.value	= CCP_XTS_AES_UNIT_SIZE_1024,
  	},
  	{
  		.size	= 512,
  		.value	= CCP_XTS_AES_UNIT_SIZE_512,
  	},
  	{
  		.size	= 256,
  		.value	= CCP_XTS_AES_UNIT_SIZE__LAST,
  	},
  	{
  		.size	= 128,
  		.value	= CCP_XTS_AES_UNIT_SIZE__LAST,
  	},
  	{
  		.size	= 64,
  		.value	= CCP_XTS_AES_UNIT_SIZE__LAST,
  	},
  	{
  		.size	= 32,
  		.value	= CCP_XTS_AES_UNIT_SIZE__LAST,
  	},
  	{
  		.size	= 16,
  		.value	= CCP_XTS_AES_UNIT_SIZE_16,
  	},
  	{
  		.size	= 1,
  		.value	= CCP_XTS_AES_UNIT_SIZE__LAST,
  	},
  };
  
  static int ccp_aes_xts_complete(struct crypto_async_request *async_req, int ret)
  {
  	struct ablkcipher_request *req = ablkcipher_request_cast(async_req);
  	struct ccp_aes_req_ctx *rctx = ablkcipher_request_ctx(req);
  
  	if (ret)
  		return ret;
  
  	memcpy(req->info, rctx->iv, AES_BLOCK_SIZE);
  
  	return 0;
  }
  
  static int ccp_aes_xts_setkey(struct crypto_ablkcipher *tfm, const u8 *key,
  			      unsigned int key_len)
  {
  	struct ccp_ctx *ctx = crypto_tfm_ctx(crypto_ablkcipher_tfm(tfm));
  
  	/* Only support 128-bit AES key with a 128-bit Tweak key,
  	 * otherwise use the fallback
  	 */
  	switch (key_len) {
  	case AES_KEYSIZE_128 * 2:
  		memcpy(ctx->u.aes.key, key, key_len);
  		break;
  	}
  	ctx->u.aes.key_len = key_len / 2;
  	sg_init_one(&ctx->u.aes.key_sg, ctx->u.aes.key, key_len);
  
  	return crypto_ablkcipher_setkey(ctx->u.aes.tfm_ablkcipher, key,
  					key_len);
  }
  
  static int ccp_aes_xts_crypt(struct ablkcipher_request *req,
  			     unsigned int encrypt)
  {
  	struct crypto_tfm *tfm =
  		crypto_ablkcipher_tfm(crypto_ablkcipher_reqtfm(req));
  	struct ccp_ctx *ctx = crypto_tfm_ctx(req->base.tfm);
  	struct ccp_aes_req_ctx *rctx = ablkcipher_request_ctx(req);
  	unsigned int unit;
  	int ret;
  
  	if (!ctx->u.aes.key_len)
  		return -EINVAL;
  
  	if (req->nbytes & (AES_BLOCK_SIZE - 1))
  		return -EINVAL;
  
  	if (!req->info)
  		return -EINVAL;
  
  	for (unit = 0; unit < ARRAY_SIZE(unit_size_map); unit++)
  		if (!(req->nbytes & (unit_size_map[unit].size - 1)))
  			break;
  
  	if ((unit_size_map[unit].value == CCP_XTS_AES_UNIT_SIZE__LAST) ||
  	    (ctx->u.aes.key_len != AES_KEYSIZE_128)) {
  		/* Use the fallback to process the request for any
  		 * unsupported unit sizes or key sizes
  		 */
  		ablkcipher_request_set_tfm(req, ctx->u.aes.tfm_ablkcipher);
  		ret = (encrypt) ? crypto_ablkcipher_encrypt(req) :
  				  crypto_ablkcipher_decrypt(req);
  		ablkcipher_request_set_tfm(req, __crypto_ablkcipher_cast(tfm));
  
  		return ret;
  	}
  
  	memcpy(rctx->iv, req->info, AES_BLOCK_SIZE);
  	sg_init_one(&rctx->iv_sg, rctx->iv, AES_BLOCK_SIZE);
  
  	memset(&rctx->cmd, 0, sizeof(rctx->cmd));
  	INIT_LIST_HEAD(&rctx->cmd.entry);
  	rctx->cmd.engine = CCP_ENGINE_XTS_AES_128;
  	rctx->cmd.u.xts.action = (encrypt) ? CCP_AES_ACTION_ENCRYPT
  					   : CCP_AES_ACTION_DECRYPT;
  	rctx->cmd.u.xts.unit_size = unit_size_map[unit].value;
  	rctx->cmd.u.xts.key = &ctx->u.aes.key_sg;
  	rctx->cmd.u.xts.key_len = ctx->u.aes.key_len;
  	rctx->cmd.u.xts.iv = &rctx->iv_sg;
  	rctx->cmd.u.xts.iv_len = AES_BLOCK_SIZE;
  	rctx->cmd.u.xts.src = req->src;
  	rctx->cmd.u.xts.src_len = req->nbytes;
  	rctx->cmd.u.xts.dst = req->dst;
  
  	ret = ccp_crypto_enqueue_request(&req->base, &rctx->cmd);
  
  	return ret;
  }
  
  static int ccp_aes_xts_encrypt(struct ablkcipher_request *req)
  {
  	return ccp_aes_xts_crypt(req, 1);
  }
  
  static int ccp_aes_xts_decrypt(struct ablkcipher_request *req)
  {
  	return ccp_aes_xts_crypt(req, 0);
  }
  
  static int ccp_aes_xts_cra_init(struct crypto_tfm *tfm)
  {
  	struct ccp_ctx *ctx = crypto_tfm_ctx(tfm);
  	struct crypto_ablkcipher *fallback_tfm;
  
  	ctx->complete = ccp_aes_xts_complete;
  	ctx->u.aes.key_len = 0;
  
  	fallback_tfm = crypto_alloc_ablkcipher(tfm->__crt_alg->cra_name, 0,
  					       CRYPTO_ALG_ASYNC |
  					       CRYPTO_ALG_NEED_FALLBACK);
  	if (IS_ERR(fallback_tfm)) {
  		pr_warn("could not load fallback driver %s
  ",
  			tfm->__crt_alg->cra_name);
  		return PTR_ERR(fallback_tfm);
  	}
  	ctx->u.aes.tfm_ablkcipher = fallback_tfm;
  
  	tfm->crt_ablkcipher.reqsize = sizeof(struct ccp_aes_req_ctx) +
  				      fallback_tfm->base.crt_ablkcipher.reqsize;
  
  	return 0;
  }
  
  static void ccp_aes_xts_cra_exit(struct crypto_tfm *tfm)
  {
  	struct ccp_ctx *ctx = crypto_tfm_ctx(tfm);
  
  	if (ctx->u.aes.tfm_ablkcipher)
  		crypto_free_ablkcipher(ctx->u.aes.tfm_ablkcipher);
  	ctx->u.aes.tfm_ablkcipher = NULL;
  }
  
  
  static int ccp_register_aes_xts_alg(struct list_head *head,
  				    const struct ccp_aes_xts_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);
  
  	alg = &ccp_alg->alg;
  
  	snprintf(alg->cra_name, CRYPTO_MAX_ALG_NAME, "%s", def->name);
  	snprintf(alg->cra_driver_name, CRYPTO_MAX_ALG_NAME, "%s",
  		 def->drv_name);
  	alg->cra_flags = CRYPTO_ALG_TYPE_ABLKCIPHER | CRYPTO_ALG_ASYNC |
  			 CRYPTO_ALG_KERN_DRIVER_ONLY |
  			 CRYPTO_ALG_NEED_FALLBACK;
  	alg->cra_blocksize = AES_BLOCK_SIZE;
  	alg->cra_ctxsize = sizeof(struct ccp_ctx);
  	alg->cra_priority = CCP_CRA_PRIORITY;
  	alg->cra_type = &crypto_ablkcipher_type;
  	alg->cra_ablkcipher.setkey = ccp_aes_xts_setkey;
  	alg->cra_ablkcipher.encrypt = ccp_aes_xts_encrypt;
  	alg->cra_ablkcipher.decrypt = ccp_aes_xts_decrypt;
  	alg->cra_ablkcipher.min_keysize = AES_MIN_KEY_SIZE * 2;
  	alg->cra_ablkcipher.max_keysize = AES_MAX_KEY_SIZE * 2;
  	alg->cra_ablkcipher.ivsize = AES_BLOCK_SIZE;
  	alg->cra_init = ccp_aes_xts_cra_init;
  	alg->cra_exit = ccp_aes_xts_cra_exit;
  	alg->cra_module = THIS_MODULE;
  
  	ret = crypto_register_alg(alg);
  	if (ret) {
  		pr_err("%s ablkcipher algorithm registration error (%d)
  ",
  			alg->cra_name, ret);
  		kfree(ccp_alg);
  		return ret;
  	}
  
  	list_add(&ccp_alg->entry, head);
  
  	return 0;
  }
  
  int ccp_register_aes_xts_algs(struct list_head *head)
  {
  	int i, ret;
  
  	for (i = 0; i < ARRAY_SIZE(aes_xts_algs); i++) {
  		ret = ccp_register_aes_xts_alg(head, &aes_xts_algs[i]);
  		if (ret)
  			return ret;
  	}
  
  	return 0;
  }