// 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");