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// SPDX-License-Identifier: GPL-2.0-only
/*
* T10 Data Integrity Field CRC16 calculation
*
* Copyright (c) 2007 Oracle Corporation. All rights reserved.
* Written by Martin K. Petersen <martin.petersen@oracle.com>
*/
#include <linux/types.h>
#include <linux/module.h>
#include <linux/crc-t10dif.h>
#include <linux/err.h>
#include <linux/init.h>
#include <crypto/hash.h>
#include <crypto/algapi.h>
#include <linux/static_key.h>
#include <linux/notifier.h>
static struct crypto_shash __rcu *crct10dif_tfm;
static DEFINE_STATIC_KEY_TRUE(crct10dif_fallback);
static DEFINE_MUTEX(crc_t10dif_mutex);
static struct work_struct crct10dif_rehash_work;
static int crc_t10dif_notify(struct notifier_block *self, unsigned long val, void *data)
{
struct crypto_alg *alg = data;
if (val != CRYPTO_MSG_ALG_LOADED ||
strcmp(alg->cra_name, CRC_T10DIF_STRING))
return NOTIFY_DONE;
schedule_work(&crct10dif_rehash_work);
return NOTIFY_OK;
}
static void crc_t10dif_rehash(struct work_struct *work)
{
struct crypto_shash *new, *old;
mutex_lock(&crc_t10dif_mutex);
old = rcu_dereference_protected(crct10dif_tfm,
lockdep_is_held(&crc_t10dif_mutex));
new = crypto_alloc_shash(CRC_T10DIF_STRING, 0, 0);
if (IS_ERR(new)) {
mutex_unlock(&crc_t10dif_mutex);
return;
}
rcu_assign_pointer(crct10dif_tfm, new);
mutex_unlock(&crc_t10dif_mutex);
if (old) {
synchronize_rcu();
crypto_free_shash(old);
} else {
static_branch_disable(&crct10dif_fallback);
}
}
static struct notifier_block crc_t10dif_nb = {
.notifier_call = crc_t10dif_notify,
};
__u16 crc_t10dif_update(__u16 crc, const unsigned char *buffer, size_t len)
{
struct {
struct shash_desc shash;
__u16 crc;
} desc;
int err;
if (static_branch_unlikely(&crct10dif_fallback))
return crc_t10dif_generic(crc, buffer, len);
rcu_read_lock();
desc.shash.tfm = rcu_dereference(crct10dif_tfm);
desc.crc = crc;
err = crypto_shash_update(&desc.shash, buffer, len);
rcu_read_unlock();
BUG_ON(err);
return desc.crc;
}
EXPORT_SYMBOL(crc_t10dif_update);
__u16 crc_t10dif(const unsigned char *buffer, size_t len)
{
return crc_t10dif_update(0, buffer, len);
}
EXPORT_SYMBOL(crc_t10dif);
static int __init crc_t10dif_mod_init(void)
{
INIT_WORK(&crct10dif_rehash_work, crc_t10dif_rehash);
crypto_register_notifier(&crc_t10dif_nb);
crc_t10dif_rehash(&crct10dif_rehash_work);
return 0;
}
static void __exit crc_t10dif_mod_fini(void)
{
crypto_unregister_notifier(&crc_t10dif_nb);
cancel_work_sync(&crct10dif_rehash_work);
crypto_free_shash(rcu_dereference_protected(crct10dif_tfm, 1));
}
module_init(crc_t10dif_mod_init);
module_exit(crc_t10dif_mod_fini);
static int crc_t10dif_transform_show(char *buffer, const struct kernel_param *kp)
{
struct crypto_shash *tfm;
int len;
if (static_branch_unlikely(&crct10dif_fallback))
return sprintf(buffer, "fallback\n");
rcu_read_lock();
tfm = rcu_dereference(crct10dif_tfm);
len = snprintf(buffer, PAGE_SIZE, "%s\n",
crypto_shash_driver_name(tfm));
rcu_read_unlock();
return len;
}
module_param_call(transform, NULL, crc_t10dif_transform_show, NULL, 0444);
MODULE_DESCRIPTION("T10 DIF CRC calculation (library API)");
MODULE_LICENSE("GPL");
MODULE_SOFTDEP("pre: crct10dif");