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 19 static struct crypto_shash __rcu *crct10dif_tfm; 20 static DEFINE_STATIC_KEY_TRUE(crct10dif_fallback); 21 static DEFINE_MUTEX(crc_t10dif_mutex); 22 static struct work_struct crct10dif_rehash_work; 23 24 static 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 36 static 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 59 static 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 } 84 EXPORT_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 } 90 EXPORT_SYMBOL(crc_t10dif); 91 92 static 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 } 99 100 static 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 } 106 107 module_init(crc_t10dif_mod_init); 108 module_exit(crc_t10dif_mod_fini); 109 110 static 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 } 126 127 module_param_call(transform, NULL, crc_t10dif_transform_show, NULL, 0444); 128 129 MODULE_DESCRIPTION("T10 DIF CRC calculation (library API)"); 130 MODULE_LICENSE("GPL"); 131 MODULE_SOFTDEP("pre: crct10dif"); 132