// SPDX-License-Identifier: GPL-2.0
/* GPL HEADER START
 *
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 only,
 * as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License version 2 for more details (a copy is included
 * in the LICENSE file that accompanied this code).
 *
 * You should have received a copy of the GNU General Public License
 * version 2 along with this program; If not, see http://www.gnu.org/licenses
 *
 * Please  visit http://www.xyratex.com/contact if you need additional
 * information or have any questions.
 *
 * GPL HEADER END
 */

/*
 * Copyright 2012 Xyratex Technology Limited
 *
 * Copyright (c) 2012, Intel Corporation.
 */

#include <crypto/hash.h>
#include <linux/scatterlist.h>
#include <linux/libcfs/libcfs.h>
#include <linux/libcfs/libcfs_crypto.h>
#include "linux-crypto.h"

/**
 *  Array of hash algorithm speed in MByte per second
 */
static int cfs_crypto_hash_speeds[CFS_HASH_ALG_MAX];

/**
 * Initialize the state descriptor for the specified hash algorithm.
 *
 * An internal routine to allocate the hash-specific state in \a req for
 * use with cfs_crypto_hash_digest() to compute the hash of a single message,
 * though possibly in multiple chunks.  The descriptor internal state should
 * be freed with cfs_crypto_hash_final().
 *
 * \param[in]     hash_alg      hash algorithm id (CFS_HASH_ALG_*)
 * \param[out]    type          pointer to the hash description in hash_types[]
 *                              array
 * \param[in,out] req           hash state descriptor to be initialized
 * \param[in]     key           initial hash value/state, NULL to use default
 *                              value
 * \param[in]     key_len       length of \a key
 *
 * \retval                      0 on success
 * \retval                      negative errno on failure
 */
static int cfs_crypto_hash_alloc(enum cfs_crypto_hash_alg hash_alg,
                                 const struct cfs_crypto_hash_type **type,
                                 struct ahash_request **req,
                                 unsigned char *key,
                                 unsigned int key_len)
{
        struct crypto_ahash *tfm;
        int err = 0;

        *type = cfs_crypto_hash_type(hash_alg);

        if (!*type) {
                CWARN("Unsupported hash algorithm id = %d, max id is %d\n",
                      hash_alg, CFS_HASH_ALG_MAX);
                return -EINVAL;
        }
        tfm = crypto_alloc_ahash((*type)->cht_name, 0, CRYPTO_ALG_ASYNC);

        if (IS_ERR(tfm)) {
                CDEBUG(D_INFO, "Failed to alloc crypto hash %s\n",
                       (*type)->cht_name);
                return PTR_ERR(tfm);
        }

        *req = ahash_request_alloc(tfm, GFP_KERNEL);
        if (!*req) {
                CDEBUG(D_INFO, "Failed to alloc ahash_request for %s\n",
                       (*type)->cht_name);
                crypto_free_ahash(tfm);
                return -ENOMEM;
        }

        ahash_request_set_callback(*req, 0, NULL, NULL);

        if (key)
                err = crypto_ahash_setkey(tfm, key, key_len);
        else if ((*type)->cht_key)
                err = crypto_ahash_setkey(tfm,
                                          (unsigned char *)&((*type)->cht_key),
                                          (*type)->cht_size);

        if (err) {
                ahash_request_free(*req);
                crypto_free_ahash(tfm);
                return err;
        }

        CDEBUG(D_INFO, "Using crypto hash: %s (%s) speed %d MB/s\n",
               crypto_ahash_alg_name(tfm), crypto_ahash_driver_name(tfm),
               cfs_crypto_hash_speeds[hash_alg]);

        err = crypto_ahash_init(*req);
        if (err) {
                ahash_request_free(*req);
                crypto_free_ahash(tfm);
        }
        return err;
}

/**
 * Calculate hash digest for the passed buffer.
 *
 * This should be used when computing the hash on a single contiguous buffer.
 * It combines the hash initialization, computation, and cleanup.
 *
 * \param[in]     hash_alg      id of hash algorithm (CFS_HASH_ALG_*)
 * \param[in]     buf           data buffer on which to compute hash
 * \param[in]     buf_len       length of \a buf in bytes
 * \param[in]     key           initial value/state for algorithm,
 *                              if \a key = NULL use default initial value
 * \param[in]     key_len       length of \a key in bytes
 * \param[out]    hash          pointer to computed hash value,
 *                              if \a hash = NULL then \a hash_len is to digest
 *                              size in bytes, retval -ENOSPC
 * \param[in,out] hash_len      size of \a hash buffer
 *
 * \retval -EINVAL              \a buf, \a buf_len, \a hash_len,
 *                              \a hash_alg invalid
 * \retval -ENOENT              \a hash_alg is unsupported
 * \retval -ENOSPC              \a hash is NULL, or \a hash_len less than
 *                              digest size
 * \retval                      0 for success
 * \retval                      negative errno for other errors from lower
 *                              layers.
 */
int cfs_crypto_hash_digest(enum cfs_crypto_hash_alg hash_alg,
                           const void *buf, unsigned int buf_len,
                           unsigned char *key, unsigned int key_len,
                           unsigned char *hash, unsigned int *hash_len)
{
        struct scatterlist sl;
        struct ahash_request *req;
        int err;
        const struct cfs_crypto_hash_type *type;

        if (!buf || !buf_len || !hash_len)
                return -EINVAL;

        err = cfs_crypto_hash_alloc(hash_alg, &type, &req, key, key_len);
        if (err)
                return err;

        if (!hash || *hash_len < type->cht_size) {
                *hash_len = type->cht_size;
                crypto_free_ahash(crypto_ahash_reqtfm(req));
                ahash_request_free(req);
                return -ENOSPC;
        }
        sg_init_one(&sl, buf, buf_len);

        ahash_request_set_crypt(req, &sl, hash, sl.length);
        err = crypto_ahash_digest(req);
        crypto_free_ahash(crypto_ahash_reqtfm(req));
        ahash_request_free(req);

        return err;
}
EXPORT_SYMBOL(cfs_crypto_hash_digest);

/**
 * Allocate and initialize descriptor for hash algorithm.
 *
 * This should be used to initialize a hash descriptor for multiple calls
 * to a single hash function when computing the hash across multiple
 * separate buffers or pages using cfs_crypto_hash_update{,_page}().
 *
 * The hash descriptor should be freed with cfs_crypto_hash_final().
 *
 * \param[in] hash_alg  algorithm id (CFS_HASH_ALG_*)
 * \param[in] key       initial value/state for algorithm, if \a key = NULL
 *                      use default initial value
 * \param[in] key_len   length of \a key in bytes
 *
 * \retval              pointer to descriptor of hash instance
 * \retval              ERR_PTR(errno) in case of error
 */
struct ahash_request *
cfs_crypto_hash_init(enum cfs_crypto_hash_alg hash_alg,
                     unsigned char *key, unsigned int key_len)
{
        struct ahash_request *req;
        int err;
        const struct cfs_crypto_hash_type *type;

        err = cfs_crypto_hash_alloc(hash_alg, &type, &req, key, key_len);

        if (err)
                return ERR_PTR(err);
        return req;
}
EXPORT_SYMBOL(cfs_crypto_hash_init);

/**
 * Update hash digest computed on data within the given \a page
 *
 * \param[in] hreq      hash state descriptor
 * \param[in] page      data page on which to compute the hash
 * \param[in] offset    offset within \a page at which to start hash
 * \param[in] len       length of data on which to compute hash
 *
 * \retval              0 for success
 * \retval              negative errno on failure
 */
int cfs_crypto_hash_update_page(struct ahash_request *req,
                                struct page *page, unsigned int offset,
                                unsigned int len)
{
        struct scatterlist sl;

        sg_init_table(&sl, 1);
        sg_set_page(&sl, page, len, offset & ~PAGE_MASK);

        ahash_request_set_crypt(req, &sl, NULL, sl.length);
        return crypto_ahash_update(req);
}
EXPORT_SYMBOL(cfs_crypto_hash_update_page);

/**
 * Update hash digest computed on the specified data
 *
 * \param[in] req       hash state descriptor
 * \param[in] buf       data buffer on which to compute the hash
 * \param[in] buf_len   length of \buf on which to compute hash
 *
 * \retval              0 for success
 * \retval              negative errno on failure
 */
int cfs_crypto_hash_update(struct ahash_request *req,
                           const void *buf, unsigned int buf_len)
{
        struct scatterlist sl;

        sg_init_one(&sl, buf, buf_len);

        ahash_request_set_crypt(req, &sl, NULL, sl.length);
        return crypto_ahash_update(req);
}
EXPORT_SYMBOL(cfs_crypto_hash_update);

/**
 * Finish hash calculation, copy hash digest to buffer, clean up hash descriptor
 *
 * \param[in]     req           hash descriptor
 * \param[out]    hash          pointer to hash buffer to store hash digest
 * \param[in,out] hash_len      pointer to hash buffer size, if \a req = NULL
 *                              only free \a req instead of computing the hash
 *
 * \retval      0 for success
 * \retval      -EOVERFLOW if hash_len is too small for the hash digest
 * \retval      negative errno for other errors from lower layers
 */
int cfs_crypto_hash_final(struct ahash_request *req,
                          unsigned char *hash, unsigned int *hash_len)
{
        int err;
        int size = crypto_ahash_digestsize(crypto_ahash_reqtfm(req));

        if (!hash || !hash_len) {
                err = 0;
                goto free_ahash;
        }
        if (*hash_len < size) {
                err = -EOVERFLOW;
                goto free_ahash;
        }

        ahash_request_set_crypt(req, NULL, hash, 0);
        err = crypto_ahash_final(req);
        if (!err)
                *hash_len = size;
free_ahash:
        crypto_free_ahash(crypto_ahash_reqtfm(req));
        ahash_request_free(req);
        return err;
}
EXPORT_SYMBOL(cfs_crypto_hash_final);

/**
 * Compute the speed of specified hash function
 *
 * Run a speed test on the given hash algorithm on buffer of the given size.
 * The speed is stored internally in the cfs_crypto_hash_speeds[] array, and
 * is available through the cfs_crypto_hash_speed() function.
 *
 * \param[in] hash_alg  hash algorithm id (CFS_HASH_ALG_*)
 * \param[in] buf       data buffer on which to compute the hash
 * \param[in] buf_len   length of \buf on which to compute hash
 */
static void cfs_crypto_performance_test(enum cfs_crypto_hash_alg hash_alg)
{
        int buf_len = max(PAGE_SIZE, 1048576UL);
        void *buf;
        unsigned long start, end;
        int bcount, err = 0;
        struct page *page;
        unsigned char hash[CFS_CRYPTO_HASH_DIGESTSIZE_MAX];
        unsigned int hash_len = sizeof(hash);

        page = alloc_page(GFP_KERNEL);
        if (!page) {
                err = -ENOMEM;
                goto out_err;
        }

        buf = kmap(page);
        memset(buf, 0xAD, PAGE_SIZE);
        kunmap(page);

        for (start = jiffies, end = start + msecs_to_jiffies(MSEC_PER_SEC),
             bcount = 0; time_before(jiffies, end); bcount++) {
                struct ahash_request *hdesc;
                int i;

                hdesc = cfs_crypto_hash_init(hash_alg, NULL, 0);
                if (IS_ERR(hdesc)) {
                        err = PTR_ERR(hdesc);
                        break;
                }

                for (i = 0; i < buf_len / PAGE_SIZE; i++) {
                        err = cfs_crypto_hash_update_page(hdesc, page, 0,
                                                          PAGE_SIZE);
                        if (err)
                                break;
                }

                err = cfs_crypto_hash_final(hdesc, hash, &hash_len);
                if (err)
                        break;
        }
        end = jiffies;
        __free_page(page);
out_err:
        if (err) {
                cfs_crypto_hash_speeds[hash_alg] = err;
                CDEBUG(D_INFO, "Crypto hash algorithm %s test error: rc = %d\n",
                       cfs_crypto_hash_name(hash_alg), err);
        } else {
                unsigned long tmp;

                tmp = ((bcount * buf_len / jiffies_to_msecs(end - start)) *
                       1000) / (1024 * 1024);
                cfs_crypto_hash_speeds[hash_alg] = (int)tmp;
                CDEBUG(D_CONFIG, "Crypto hash algorithm %s speed = %d MB/s\n",
                       cfs_crypto_hash_name(hash_alg),
                       cfs_crypto_hash_speeds[hash_alg]);
        }
}

/**
 * hash speed in Mbytes per second for valid hash algorithm
 *
 * Return the performance of the specified \a hash_alg that was previously
 * computed using cfs_crypto_performance_test().
 *
 * \param[in] hash_alg  hash algorithm id (CFS_HASH_ALG_*)
 *
 * \retval              positive speed of the hash function in MB/s
 * \retval              -ENOENT if \a hash_alg is unsupported
 * \retval              negative errno if \a hash_alg speed is unavailable
 */
int cfs_crypto_hash_speed(enum cfs_crypto_hash_alg hash_alg)
{
        if (hash_alg < CFS_HASH_ALG_MAX)
                return cfs_crypto_hash_speeds[hash_alg];
        return -ENOENT;
}
EXPORT_SYMBOL(cfs_crypto_hash_speed);

/**
 * Run the performance test for all hash algorithms.
 *
 * Run the cfs_crypto_performance_test() benchmark for all of the available
 * hash functions using a 1MB buffer size.  This is a reasonable buffer size
 * for Lustre RPCs, even if the actual RPC size is larger or smaller.
 *
 * Since the setup cost and computation speed of various hash algorithms is
 * a function of the buffer size (and possibly internal contention of offload
 * engines), this speed only represents an estimate of the actual speed under
 * actual usage, but is reasonable for comparing available algorithms.
 *
 * The actual speeds are available via cfs_crypto_hash_speed() for later
 * comparison.
 *
 * \retval      0 on success
 * \retval      -ENOMEM if no memory is available for test buffer
 */
static int cfs_crypto_test_hashes(void)
{
        enum cfs_crypto_hash_alg hash_alg;

        for (hash_alg = 0; hash_alg < CFS_HASH_ALG_MAX; hash_alg++)
                cfs_crypto_performance_test(hash_alg);

        return 0;
}

static int adler32;

/**
 * Register available hash functions
 *
 * \retval      0
 */
int cfs_crypto_register(void)
{
        request_module("crc32c");

        adler32 = cfs_crypto_adler32_register();

        /* check all algorithms and do performance test */
        cfs_crypto_test_hashes();
        return 0;
}

/**
 * Unregister previously registered hash functions
 */
void cfs_crypto_unregister(void)
{
        if (!adler32)
                cfs_crypto_adler32_unregister();
}