[linux-2.6-block.git] / lib / crc-t10dif.c

// 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 int crc_t10dif_rehash(struct notifier_block *self, unsigned long val, void *data)
{
	struct crypto_alg *alg = data;
	struct crypto_shash *new, *old;

	if (val != CRYPTO_MSG_ALG_LOADED ||
	    static_key_false(&crct10dif_fallback) ||
	    strncmp(alg->cra_name, CRC_T10DIF_STRING, strlen(CRC_T10DIF_STRING)))
		return 0;

	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 0;
	}
	new = crypto_alloc_shash("crct10dif", 0, 0);
	if (IS_ERR(new)) {
		mutex_unlock(&crc_t10dif_mutex);
		return 0;
	}
	rcu_assign_pointer(crct10dif_tfm, new);
	mutex_unlock(&crc_t10dif_mutex);

	synchronize_rcu();
	crypto_free_shash(old);
	return 0;
}

static struct notifier_block crc_t10dif_nb = {
	.notifier_call = crc_t10dif_rehash,
};

__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)
{
	crypto_register_notifier(&crc_t10dif_nb);
	crct10dif_tfm = crypto_alloc_shash("crct10dif", 0, 0);
	if (IS_ERR(crct10dif_tfm)) {
		static_key_slow_inc(&crct10dif_fallback);
		crct10dif_tfm = NULL;
	}
	return 0;
}

static void __exit crc_t10dif_mod_fini(void)
{
	crypto_unregister_notifier(&crc_t10dif_nb);
	crypto_free_shash(crct10dif_tfm);
}

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)
{
	if (static_key_false(&crct10dif_fallback))
		return sprintf(buffer, "fallback\n");

	return sprintf(buffer, "%s\n",
		crypto_tfm_alg_driver_name(crypto_shash_tfm(crct10dif_tfm)));
}

module_param_call(transform, NULL, crc_t10dif_transform_show, NULL, 0644);

MODULE_DESCRIPTION("T10 DIF CRC calculation");
MODULE_LICENSE("GPL");
MODULE_SOFTDEP("pre: crct10dif");
Commit	Line	Data
40b0b3f8	1	// SPDX-License-Identifier: GPL-2.0-only
f11f594e MP	2	/*
	3	* T10 Data Integrity Field CRC16 calculation
	4	*
	5	* Copyright (c) 2007 Oracle Corporation. All rights reserved.
	6	* Written by Martin K. Petersen <martin.petersen@oracle.com>
f11f594e MP	7	*/
	8
	9	#include <linux/types.h>
	10	#include <linux/module.h>
	11	#include <linux/crc-t10dif.h>
68411521 HX	12	#include <linux/err.h>
	13	#include <linux/init.h>
	14	#include <crypto/hash.h>
b7637754	15	#include <crypto/algapi.h>
26052f9b	16	#include <linux/static_key.h>
b7637754	17	#include <linux/notifier.h>
f11f594e	18
b7637754	19	static struct crypto_shash __rcu *crct10dif_tfm;
26052f9b	20	static struct static_key crct10dif_fallback __read_mostly;
a7e7edfe	21	static DEFINE_MUTEX(crc_t10dif_mutex);
b7637754 MP	22
	23	static int crc_t10dif_rehash(struct notifier_block self, unsigned long val, void data)
	24	{
	25	struct crypto_alg *alg = data;
	26	struct crypto_shash new, old;
	27
	28	if (val != CRYPTO_MSG_ALG_LOADED \|\|
	29	static_key_false(&crct10dif_fallback) \|\|
	30	strncmp(alg->cra_name, CRC_T10DIF_STRING, strlen(CRC_T10DIF_STRING)))
	31	return 0;
	32
	33	mutex_lock(&crc_t10dif_mutex);
	34	old = rcu_dereference_protected(crct10dif_tfm,
	35	lockdep_is_held(&crc_t10dif_mutex));
	36	if (!old) {
	37	mutex_unlock(&crc_t10dif_mutex);
	38	return 0;
	39	}
	40	new = crypto_alloc_shash("crct10dif", 0, 0);
	41	if (IS_ERR(new)) {
	42	mutex_unlock(&crc_t10dif_mutex);
	43	return 0;
	44	}
	45	rcu_assign_pointer(crct10dif_tfm, new);
	46	mutex_unlock(&crc_t10dif_mutex);
	47
	48	synchronize_rcu();
	49	crypto_free_shash(old);
	50	return 0;
	51	}
	52
	53	static struct notifier_block crc_t10dif_nb = {
	54	.notifier_call = crc_t10dif_rehash,
	55	};
f11f594e	56
10081fb5	57	__u16 crc_t10dif_update(__u16 crc, const unsigned char *buffer, size_t len)
f11f594e	58	{
68411521 HX	59	struct {
	60	struct shash_desc shash;
	61	char ctx[2];
	62	} desc;
	63	int err;
	64
26052f9b	65	if (static_key_false(&crct10dif_fallback))
10081fb5	66	return crc_t10dif_generic(crc, buffer, len);
26052f9b	67
b7637754 MP	68	rcu_read_lock();
b7637754 MP	69	desc.shash.tfm = rcu_dereference(crct10dif_tfm);
10081fb5	70	(__u16 )desc.ctx = crc;
f11f594e	71
68411521	72	err = crypto_shash_update(&desc.shash, buffer, len);
b7637754 MP	73	rcu_read_unlock();
b7637754 MP	74
68411521	75	BUG_ON(err);
f11f594e	76
68411521	77	return (__u16 )desc.ctx;
f11f594e	78	}
10081fb5 AM	79	EXPORT_SYMBOL(crc_t10dif_update);
	80
	81	__u16 crc_t10dif(const unsigned char *buffer, size_t len)
	82	{
	83	return crc_t10dif_update(0, buffer, len);
	84	}
f11f594e MP	85	EXPORT_SYMBOL(crc_t10dif);
f11f594e MP	86
68411521 HX	87	static int __init crc_t10dif_mod_init(void)
68411521 HX	88	{
b7637754	89	crypto_register_notifier(&crc_t10dif_nb);
68411521	90	crct10dif_tfm = crypto_alloc_shash("crct10dif", 0, 0);
26052f9b HX	91	if (IS_ERR(crct10dif_tfm)) {
	92	static_key_slow_inc(&crct10dif_fallback);
	93	crct10dif_tfm = NULL;
	94	}
	95	return 0;
68411521 HX	96	}
	97
	98	static void __exit crc_t10dif_mod_fini(void)
	99	{
b7637754	100	crypto_unregister_notifier(&crc_t10dif_nb);
68411521 HX	101	crypto_free_shash(crct10dif_tfm);
	102	}
	103
	104	module_init(crc_t10dif_mod_init);
	105	module_exit(crc_t10dif_mod_fini);
	106
11dcb103 MP	107	static int crc_t10dif_transform_show(char buffer, const struct kernel_param kp)
	108	{
	109	if (static_key_false(&crct10dif_fallback))
	110	return sprintf(buffer, "fallback\n");
	111
	112	return sprintf(buffer, "%s\n",
	113	crypto_tfm_alg_driver_name(crypto_shash_tfm(crct10dif_tfm)));
	114	}
	115
	116	module_param_call(transform, NULL, crc_t10dif_transform_show, NULL, 0644);
	117
f11f594e MP	118	MODULE_DESCRIPTION("T10 DIF CRC calculation");
f11f594e MP	119	MODULE_LICENSE("GPL");
68411521	120	MODULE_SOFTDEP("pre: crct10dif");