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1// SPDX-License-Identifier: GPL-2.0-only2/*3 * T10 Data Integrity Field CRC16 calculation4 *5 * Copyright (c) 2007 Oracle Corporation. All rights reserved.6 * Written by Martin K. Petersen <martin.petersen@oracle.com>7 */8 9#include <linux/types.h>10#include <linux/module.h>11#include <linux/crc-t10dif.h>12#include <linux/err.h>13#include <linux/init.h>14#include <crypto/hash.h>15#include <crypto/algapi.h>16#include <linux/static_key.h>17#include <linux/notifier.h>18 19static struct crypto_shash __rcu *crct10dif_tfm;20static DEFINE_STATIC_KEY_TRUE(crct10dif_fallback);21static DEFINE_MUTEX(crc_t10dif_mutex);22static struct work_struct crct10dif_rehash_work;23 24static int crc_t10dif_notify(struct notifier_block *self, unsigned long val, void *data)25{26 struct crypto_alg *alg = data;27 28 if (val != CRYPTO_MSG_ALG_LOADED ||29 strcmp(alg->cra_name, CRC_T10DIF_STRING))30 return NOTIFY_DONE;31 32 schedule_work(&crct10dif_rehash_work);33 return NOTIFY_OK;34}35 36static void crc_t10dif_rehash(struct work_struct *work)37{38 struct crypto_shash *new, *old;39 40 mutex_lock(&crc_t10dif_mutex);41 old = rcu_dereference_protected(crct10dif_tfm,42 lockdep_is_held(&crc_t10dif_mutex));43 new = crypto_alloc_shash(CRC_T10DIF_STRING, 0, 0);44 if (IS_ERR(new)) {45 mutex_unlock(&crc_t10dif_mutex);46 return;47 }48 rcu_assign_pointer(crct10dif_tfm, new);49 mutex_unlock(&crc_t10dif_mutex);50 51 if (old) {52 synchronize_rcu();53 crypto_free_shash(old);54 } else {55 static_branch_disable(&crct10dif_fallback);56 }57}58 59static struct notifier_block crc_t10dif_nb = {60 .notifier_call = crc_t10dif_notify,61};62 63__u16 crc_t10dif_update(__u16 crc, const unsigned char *buffer, size_t len)64{65 struct {66 struct shash_desc shash;67 __u16 crc;68 } desc;69 int err;70 71 if (static_branch_unlikely(&crct10dif_fallback))72 return crc_t10dif_generic(crc, buffer, len);73 74 rcu_read_lock();75 desc.shash.tfm = rcu_dereference(crct10dif_tfm);76 desc.crc = crc;77 err = crypto_shash_update(&desc.shash, buffer, len);78 rcu_read_unlock();79 80 BUG_ON(err);81 82 return desc.crc;83}84EXPORT_SYMBOL(crc_t10dif_update);85 86__u16 crc_t10dif(const unsigned char *buffer, size_t len)87{88 return crc_t10dif_update(0, buffer, len);89}90EXPORT_SYMBOL(crc_t10dif);91 92static int __init crc_t10dif_mod_init(void)93{94 INIT_WORK(&crct10dif_rehash_work, crc_t10dif_rehash);95 crypto_register_notifier(&crc_t10dif_nb);96 crc_t10dif_rehash(&crct10dif_rehash_work);97 return 0;98}99 100static void __exit crc_t10dif_mod_fini(void)101{102 crypto_unregister_notifier(&crc_t10dif_nb);103 cancel_work_sync(&crct10dif_rehash_work);104 crypto_free_shash(rcu_dereference_protected(crct10dif_tfm, 1));105}106 107module_init(crc_t10dif_mod_init);108module_exit(crc_t10dif_mod_fini);109 110static int crc_t10dif_transform_show(char *buffer, const struct kernel_param *kp)111{112 struct crypto_shash *tfm;113 int len;114 115 if (static_branch_unlikely(&crct10dif_fallback))116 return sprintf(buffer, "fallback\n");117 118 rcu_read_lock();119 tfm = rcu_dereference(crct10dif_tfm);120 len = snprintf(buffer, PAGE_SIZE, "%s\n",121 crypto_shash_driver_name(tfm));122 rcu_read_unlock();123 124 return len;125}126 127module_param_call(transform, NULL, crc_t10dif_transform_show, NULL, 0444);128 129MODULE_DESCRIPTION("T10 DIF CRC calculation (library API)");130MODULE_LICENSE("GPL");131MODULE_SOFTDEP("pre: crct10dif");132