crc-t10dif.c
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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 struct static_key crct10dif_fallback __read_mostly;
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 ||
static_key_false(&crct10dif_fallback) ||
strncmp(alg->cra_name, CRC_T10DIF_STRING, strlen(CRC_T10DIF_STRING)))
return 0;
schedule_work(&crct10dif_rehash_work);
return 0;
}
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));
if (!old) {
mutex_unlock(&crc_t10dif_mutex);
return;
}
new = crypto_alloc_shash("crct10dif", 0, 0);
if (IS_ERR(new)) {
mutex_unlock(&crc_t10dif_mutex);
return;
}
rcu_assign_pointer(crct10dif_tfm, new);
mutex_unlock(&crc_t10dif_mutex);
synchronize_rcu();
crypto_free_shash(old);
}
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;
char ctx[2];
} desc;
int err;
if (static_key_false(&crct10dif_fallback))
return crc_t10dif_generic(crc, buffer, len);
rcu_read_lock();
desc.shash.tfm = rcu_dereference(crct10dif_tfm);
*(__u16 *)desc.ctx = crc;
err = crypto_shash_update(&desc.shash, buffer, len);
rcu_read_unlock();
BUG_ON(err);
return *(__u16 *)desc.ctx;
}
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)
{
struct crypto_shash *tfm;
INIT_WORK(&crct10dif_rehash_work, crc_t10dif_rehash);
crypto_register_notifier(&crc_t10dif_nb);
mutex_lock(&crc_t10dif_mutex);
tfm = crypto_alloc_shash("crct10dif", 0, 0);
if (IS_ERR(tfm)) {
static_key_slow_inc(&crct10dif_fallback);
tfm = NULL;
}
RCU_INIT_POINTER(crct10dif_tfm, tfm);
mutex_unlock(&crc_t10dif_mutex);
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;
const char *name;
int len;
if (static_key_false(&crct10dif_fallback))
return sprintf(buffer, "fallback\n");
rcu_read_lock();
tfm = rcu_dereference(crct10dif_tfm);
if (!tfm) {
len = sprintf(buffer, "init\n");
goto unlock;
}
name = crypto_tfm_alg_driver_name(crypto_shash_tfm(tfm));
len = sprintf(buffer, "%s\n", name);
unlock:
rcu_read_unlock();
return len;
}
module_param_call(transform, NULL, crc_t10dif_transform_show, NULL, 0644);
MODULE_DESCRIPTION("T10 DIF CRC calculation");
MODULE_LICENSE("GPL");
MODULE_SOFTDEP("pre: crct10dif");