/*
   * AMD Cryptographic Coprocessor (CCP) SHA 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/hash.h>
  #include <crypto/internal/hash.h>
  #include <crypto/sha.h>
  #include <crypto/scatterwalk.h>
  
  #include "ccp-crypto.h"
  
  
  struct ccp_sha_result {
  	struct completion completion;
  	int err;
  };
  
  static void ccp_sync_hash_complete(struct crypto_async_request *req, int err)
  {
  	struct ccp_sha_result *result = req->data;
  
  	if (err == -EINPROGRESS)
  		return;
  
  	result->err = err;
  	complete(&result->completion);
  }
  
  static int ccp_sync_hash(struct crypto_ahash *tfm, u8 *buf,
  			 struct scatterlist *sg, unsigned int len)
  {
  	struct ccp_sha_result result;
  	struct ahash_request *req;
  	int ret;
  
  	init_completion(&result.completion);
  
  	req = ahash_request_alloc(tfm, GFP_KERNEL);
  	if (!req)
  		return -ENOMEM;
  
  	ahash_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG,
  				   ccp_sync_hash_complete, &result);
  	ahash_request_set_crypt(req, sg, buf, len);
  
  	ret = crypto_ahash_digest(req);
  	if ((ret == -EINPROGRESS) || (ret == -EBUSY)) {
  		ret = wait_for_completion_interruptible(&result.completion);
  		if (!ret)
  			ret = result.err;
  	}
  
  	ahash_request_free(req);
  
  	return ret;
  }
  
  static int ccp_sha_finish_hmac(struct crypto_async_request *async_req)
  {
  	struct ahash_request *req = ahash_request_cast(async_req);
  	struct crypto_ahash *tfm = crypto_ahash_reqtfm(req);
  	struct ccp_ctx *ctx = crypto_ahash_ctx(tfm);
  	struct ccp_sha_req_ctx *rctx = ahash_request_ctx(req);
  	struct scatterlist sg[2];
  	unsigned int block_size =
  		crypto_tfm_alg_blocksize(crypto_ahash_tfm(tfm));
  	unsigned int digest_size = crypto_ahash_digestsize(tfm);
  
  	sg_init_table(sg, ARRAY_SIZE(sg));
  	sg_set_buf(&sg[0], ctx->u.sha.opad, block_size);
  	sg_set_buf(&sg[1], rctx->ctx, digest_size);
  
  	return ccp_sync_hash(ctx->u.sha.hmac_tfm, req->result, sg,
  			     block_size + digest_size);
  }
  
  static int ccp_sha_complete(struct crypto_async_request *async_req, int ret)
  {
  	struct ahash_request *req = ahash_request_cast(async_req);
  	struct crypto_ahash *tfm = crypto_ahash_reqtfm(req);
  	struct ccp_ctx *ctx = crypto_ahash_ctx(tfm);
  	struct ccp_sha_req_ctx *rctx = ahash_request_ctx(req);
  	unsigned int digest_size = crypto_ahash_digestsize(tfm);
  
  	if (ret)
  		goto e_free;
  
  	if (rctx->hash_rem) {
  		/* Save remaining data to buffer */
  		unsigned int offset = rctx->nbytes - rctx->hash_rem;
  		scatterwalk_map_and_copy(rctx->buf, rctx->src,
  					 offset, rctx->hash_rem, 0);
  		rctx->buf_count = rctx->hash_rem;
  	} else
  		rctx->buf_count = 0;
  
  	/* Update result area if supplied */
  	if (req->result)
  		memcpy(req->result, rctx->ctx, digest_size);
  
  	/* If we're doing an HMAC, we need to perform that on the final op */
  	if (rctx->final && ctx->u.sha.key_len)
  		ret = ccp_sha_finish_hmac(async_req);
  
  e_free:
  	sg_free_table(&rctx->data_sg);
  
  	return ret;
  }
  
  static int ccp_do_sha_update(struct ahash_request *req, unsigned int nbytes,
  			     unsigned int final)
  {
  	struct crypto_ahash *tfm = crypto_ahash_reqtfm(req);
  	struct ccp_sha_req_ctx *rctx = ahash_request_ctx(req);
  	struct scatterlist *sg;
  	unsigned int block_size =
  		crypto_tfm_alg_blocksize(crypto_ahash_tfm(tfm));
  	unsigned int sg_count;
  	gfp_t gfp;
  	u64 len;
  	int ret;
  
  	len = (u64)rctx->buf_count + (u64)nbytes;
  
  	if (!final && (len <= block_size)) {
  		scatterwalk_map_and_copy(rctx->buf + rctx->buf_count, req->src,
  					 0, nbytes, 0);
  		rctx->buf_count += nbytes;
  
  		return 0;
  	}
  
  	rctx->src = req->src;
  	rctx->nbytes = nbytes;
  
  	rctx->final = final;
  	rctx->hash_rem = final ? 0 : len & (block_size - 1);
  	rctx->hash_cnt = len - rctx->hash_rem;
  	if (!final && !rctx->hash_rem) {
  		/* CCP can't do zero length final, so keep some data around */
  		rctx->hash_cnt -= block_size;
  		rctx->hash_rem = block_size;
  	}
  
  	/* Initialize the context scatterlist */
  	sg_init_one(&rctx->ctx_sg, rctx->ctx, sizeof(rctx->ctx));
  
  	sg = NULL;
  	if (rctx->buf_count && nbytes) {
  		/* Build the data scatterlist table - allocate enough entries
  		 * for both data pieces (buffer and input data)
  		 */
  		gfp = req->base.flags & CRYPTO_TFM_REQ_MAY_SLEEP ?
  			GFP_KERNEL : GFP_ATOMIC;
  		sg_count = sg_nents(req->src) + 1;
  		ret = sg_alloc_table(&rctx->data_sg, sg_count, gfp);
  		if (ret)
  			return ret;
  
  		sg_init_one(&rctx->buf_sg, rctx->buf, rctx->buf_count);
  		sg = ccp_crypto_sg_table_add(&rctx->data_sg, &rctx->buf_sg);
  		sg = ccp_crypto_sg_table_add(&rctx->data_sg, req->src);
  		sg_mark_end(sg);
  
  		sg = rctx->data_sg.sgl;
  	} else if (rctx->buf_count) {
  		sg_init_one(&rctx->buf_sg, rctx->buf, rctx->buf_count);
  
  		sg = &rctx->buf_sg;
  	} else if (nbytes) {
  		sg = req->src;
  	}
  
  	rctx->msg_bits += (rctx->hash_cnt << 3);	/* Total in bits */
  
  	memset(&rctx->cmd, 0, sizeof(rctx->cmd));
  	INIT_LIST_HEAD(&rctx->cmd.entry);
  	rctx->cmd.engine = CCP_ENGINE_SHA;
  	rctx->cmd.u.sha.type = rctx->type;
  	rctx->cmd.u.sha.ctx = &rctx->ctx_sg;
  	rctx->cmd.u.sha.ctx_len = sizeof(rctx->ctx);
  	rctx->cmd.u.sha.src = sg;
  	rctx->cmd.u.sha.src_len = rctx->hash_cnt;
  	rctx->cmd.u.sha.final = rctx->final;
  	rctx->cmd.u.sha.msg_bits = rctx->msg_bits;
  
  	rctx->first = 0;
  
  	ret = ccp_crypto_enqueue_request(&req->base, &rctx->cmd);
  
  	return ret;
  }
  
  static int ccp_sha_init(struct ahash_request *req)
  {
  	struct crypto_ahash *tfm = crypto_ahash_reqtfm(req);
  	struct ccp_ctx *ctx = crypto_ahash_ctx(tfm);
  	struct ccp_sha_req_ctx *rctx = ahash_request_ctx(req);
  	struct ccp_crypto_ahash_alg *alg =
  		ccp_crypto_ahash_alg(crypto_ahash_tfm(tfm));
  	unsigned int block_size =
  		crypto_tfm_alg_blocksize(crypto_ahash_tfm(tfm));
  
  	memset(rctx, 0, sizeof(*rctx));
  
  	memcpy(rctx->ctx, alg->init, sizeof(rctx->ctx));
  	rctx->type = alg->type;
  	rctx->first = 1;
  
  	if (ctx->u.sha.key_len) {
  		/* Buffer the HMAC key for first update */
  		memcpy(rctx->buf, ctx->u.sha.ipad, block_size);
  		rctx->buf_count = block_size;
  	}
  
  	return 0;
  }
  
  static int ccp_sha_update(struct ahash_request *req)
  {
  	return ccp_do_sha_update(req, req->nbytes, 0);
  }
  
  static int ccp_sha_final(struct ahash_request *req)
  {
  	return ccp_do_sha_update(req, 0, 1);
  }
  
  static int ccp_sha_finup(struct ahash_request *req)
  {
  	return ccp_do_sha_update(req, req->nbytes, 1);
  }
  
  static int ccp_sha_digest(struct ahash_request *req)
  {
  	int ret;
  
  	ret = ccp_sha_init(req);
  	if (ret)
  		return ret;
  
  	return ccp_sha_finup(req);
  }
  
  static int ccp_sha_setkey(struct crypto_ahash *tfm, const u8 *key,
  			  unsigned int key_len)
  {
  	struct ccp_ctx *ctx = crypto_tfm_ctx(crypto_ahash_tfm(tfm));
  	struct scatterlist sg;
  	unsigned int block_size =
  		crypto_tfm_alg_blocksize(crypto_ahash_tfm(tfm));
  	unsigned int digest_size = crypto_ahash_digestsize(tfm);
  	int i, ret;
  
  	/* Set to zero until complete */
  	ctx->u.sha.key_len = 0;
  
  	/* Clear key area to provide zero padding for keys smaller
  	 * than the block size
  	 */
  	memset(ctx->u.sha.key, 0, sizeof(ctx->u.sha.key));
  
  	if (key_len > block_size) {
  		/* Must hash the input key */
  		sg_init_one(&sg, key, key_len);
  		ret = ccp_sync_hash(tfm, ctx->u.sha.key, &sg, key_len);
  		if (ret) {
  			crypto_ahash_set_flags(tfm, CRYPTO_TFM_RES_BAD_KEY_LEN);
  			return -EINVAL;
  		}
  
  		key_len = digest_size;
  	} else
  		memcpy(ctx->u.sha.key, key, key_len);
  
  	for (i = 0; i < block_size; i++) {
  		ctx->u.sha.ipad[i] = ctx->u.sha.key[i] ^ 0x36;
  		ctx->u.sha.opad[i] = ctx->u.sha.key[i] ^ 0x5c;
  	}
  
  	ctx->u.sha.key_len = key_len;
  
  	return 0;
  }
  
  static int ccp_sha_cra_init(struct crypto_tfm *tfm)
  {
  	struct ccp_ctx *ctx = crypto_tfm_ctx(tfm);
  	struct crypto_ahash *ahash = __crypto_ahash_cast(tfm);
  
  	ctx->complete = ccp_sha_complete;
  	ctx->u.sha.key_len = 0;
  
  	crypto_ahash_set_reqsize(ahash, sizeof(struct ccp_sha_req_ctx));
  
  	return 0;
  }
  
  static void ccp_sha_cra_exit(struct crypto_tfm *tfm)
  {
  }
  
  static int ccp_hmac_sha_cra_init(struct crypto_tfm *tfm)
  {
  	struct ccp_ctx *ctx = crypto_tfm_ctx(tfm);
  	struct ccp_crypto_ahash_alg *alg = ccp_crypto_ahash_alg(tfm);
  	struct crypto_ahash *hmac_tfm;
  
  	hmac_tfm = crypto_alloc_ahash(alg->child_alg,
  				      CRYPTO_ALG_TYPE_AHASH, 0);
  	if (IS_ERR(hmac_tfm)) {
  		pr_warn("could not load driver %s need for HMAC support
  ",
  			alg->child_alg);
  		return PTR_ERR(hmac_tfm);
  	}
  
  	ctx->u.sha.hmac_tfm = hmac_tfm;
  
  	return ccp_sha_cra_init(tfm);
  }
  
  static void ccp_hmac_sha_cra_exit(struct crypto_tfm *tfm)
  {
  	struct ccp_ctx *ctx = crypto_tfm_ctx(tfm);
  
  	if (ctx->u.sha.hmac_tfm)
  		crypto_free_ahash(ctx->u.sha.hmac_tfm);
  
  	ccp_sha_cra_exit(tfm);
  }
  
  static const __be32 sha1_init[CCP_SHA_CTXSIZE / sizeof(__be32)] = {
  	cpu_to_be32(SHA1_H0), cpu_to_be32(SHA1_H1),
  	cpu_to_be32(SHA1_H2), cpu_to_be32(SHA1_H3),
  	cpu_to_be32(SHA1_H4), 0, 0, 0,
  };
  
  static const __be32 sha224_init[CCP_SHA_CTXSIZE / sizeof(__be32)] = {
  	cpu_to_be32(SHA224_H0), cpu_to_be32(SHA224_H1),
  	cpu_to_be32(SHA224_H2), cpu_to_be32(SHA224_H3),
  	cpu_to_be32(SHA224_H4), cpu_to_be32(SHA224_H5),
  	cpu_to_be32(SHA224_H6), cpu_to_be32(SHA224_H7),
  };
  
  static const __be32 sha256_init[CCP_SHA_CTXSIZE / sizeof(__be32)] = {
  	cpu_to_be32(SHA256_H0), cpu_to_be32(SHA256_H1),
  	cpu_to_be32(SHA256_H2), cpu_to_be32(SHA256_H3),
  	cpu_to_be32(SHA256_H4), cpu_to_be32(SHA256_H5),
  	cpu_to_be32(SHA256_H6), cpu_to_be32(SHA256_H7),
  };
  
  struct ccp_sha_def {
  	const char *name;
  	const char *drv_name;
  	const __be32 *init;
  	enum ccp_sha_type type;
  	u32 digest_size;
  	u32 block_size;
  };
  
  static struct ccp_sha_def sha_algs[] = {
  	{
  		.name		= "sha1",
  		.drv_name	= "sha1-ccp",
  		.init		= sha1_init,
  		.type		= CCP_SHA_TYPE_1,
  		.digest_size	= SHA1_DIGEST_SIZE,
  		.block_size	= SHA1_BLOCK_SIZE,
  	},
  	{
  		.name		= "sha224",
  		.drv_name	= "sha224-ccp",
  		.init		= sha224_init,
  		.type		= CCP_SHA_TYPE_224,
  		.digest_size	= SHA224_DIGEST_SIZE,
  		.block_size	= SHA224_BLOCK_SIZE,
  	},
  	{
  		.name		= "sha256",
  		.drv_name	= "sha256-ccp",
  		.init		= sha256_init,
  		.type		= CCP_SHA_TYPE_256,
  		.digest_size	= SHA256_DIGEST_SIZE,
  		.block_size	= SHA256_BLOCK_SIZE,
  	},
  };
  
  static int ccp_register_hmac_alg(struct list_head *head,
  				 const struct ccp_sha_def *def,
  				 const struct ccp_crypto_ahash_alg *base_alg)
  {
  	struct ccp_crypto_ahash_alg *ccp_alg;
  	struct ahash_alg *alg;
  	struct hash_alg_common *halg;
  	struct crypto_alg *base;
  	int ret;
  
  	ccp_alg = kzalloc(sizeof(*ccp_alg), GFP_KERNEL);
  	if (!ccp_alg)
  		return -ENOMEM;
  
  	/* Copy the base algorithm and only change what's necessary */
  	*ccp_alg = *base_alg;
  	INIT_LIST_HEAD(&ccp_alg->entry);
  
  	strncpy(ccp_alg->child_alg, def->name, CRYPTO_MAX_ALG_NAME);
  
  	alg = &ccp_alg->alg;
  	alg->setkey = ccp_sha_setkey;
  
  	halg = &alg->halg;
  
  	base = &halg->base;
  	snprintf(base->cra_name, CRYPTO_MAX_ALG_NAME, "hmac(%s)", def->name);
  	snprintf(base->cra_driver_name, CRYPTO_MAX_ALG_NAME, "hmac-%s",
  		 def->drv_name);
  	base->cra_init = ccp_hmac_sha_cra_init;
  	base->cra_exit = ccp_hmac_sha_cra_exit;
  
  	ret = crypto_register_ahash(alg);
  	if (ret) {
  		pr_err("%s ahash algorithm registration error (%d)
  ",
  			base->cra_name, ret);
  		kfree(ccp_alg);
  		return ret;
  	}
  
  	list_add(&ccp_alg->entry, head);
  
  	return ret;
  }
  
  static int ccp_register_sha_alg(struct list_head *head,
  				const struct ccp_sha_def *def)
  {
  	struct ccp_crypto_ahash_alg *ccp_alg;
  	struct ahash_alg *alg;
  	struct hash_alg_common *halg;
  	struct crypto_alg *base;
  	int ret;
  
  	ccp_alg = kzalloc(sizeof(*ccp_alg), GFP_KERNEL);
  	if (!ccp_alg)
  		return -ENOMEM;
  
  	INIT_LIST_HEAD(&ccp_alg->entry);
  
  	ccp_alg->init = def->init;
  	ccp_alg->type = def->type;
  
  	alg = &ccp_alg->alg;
  	alg->init = ccp_sha_init;
  	alg->update = ccp_sha_update;
  	alg->final = ccp_sha_final;
  	alg->finup = ccp_sha_finup;
  	alg->digest = ccp_sha_digest;
  
  	halg = &alg->halg;
  	halg->digestsize = def->digest_size;
  
  	base = &halg->base;
  	snprintf(base->cra_name, CRYPTO_MAX_ALG_NAME, "%s", def->name);
  	snprintf(base->cra_driver_name, CRYPTO_MAX_ALG_NAME, "%s",
  		 def->drv_name);
  	base->cra_flags = CRYPTO_ALG_TYPE_AHASH | CRYPTO_ALG_ASYNC |
  			  CRYPTO_ALG_KERN_DRIVER_ONLY |
  			  CRYPTO_ALG_NEED_FALLBACK;
  	base->cra_blocksize = def->block_size;
  	base->cra_ctxsize = sizeof(struct ccp_ctx);
  	base->cra_priority = CCP_CRA_PRIORITY;
  	base->cra_type = &crypto_ahash_type;
  	base->cra_init = ccp_sha_cra_init;
  	base->cra_exit = ccp_sha_cra_exit;
  	base->cra_module = THIS_MODULE;
  
  	ret = crypto_register_ahash(alg);
  	if (ret) {
  		pr_err("%s ahash algorithm registration error (%d)
  ",
  			base->cra_name, ret);
  		kfree(ccp_alg);
  		return ret;
  	}
  
  	list_add(&ccp_alg->entry, head);
  
  	ret = ccp_register_hmac_alg(head, def, ccp_alg);
  
  	return ret;
  }
  
  int ccp_register_sha_algs(struct list_head *head)
  {
  	int i, ret;
  
  	for (i = 0; i < ARRAY_SIZE(sha_algs); i++) {
  		ret = ccp_register_sha_alg(head, &sha_algs[i]);
  		if (ret)
  			return ret;
  	}
  
  	return 0;
  }