// 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");