LXR linux/lib/crc-t10dif.c

   1// SPDX-License-Identifier: GPL-2.0-only
   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>
   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