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 struct static_key crct10dif_fallback __read_mostly; 21 static DEFINE_MUTEX(crc_t10dif_mutex); 22 23 static int crc_t10dif_rehash(struct notifier_block *self, unsigned long val, void *data) 24 { 25 struct crypto_alg *alg = data; 26 struct crypto_shash *new, *old; 27 28 if (val != CRYPTO_MSG_ALG_LOADED || 29 static_key_false(&crct10dif_fallback) || 30 strncmp(alg->cra_name, CRC_T10DIF_STRING, strlen(CRC_T10DIF_STRING))) 31 return 0; 32 33 mutex_lock(&crc_t10dif_mutex); 34 old = rcu_dereference_protected(crct10dif_tfm, 35 lockdep_is_held(&crc_t10dif_mutex)); 36 if (!old) { 37 mutex_unlock(&crc_t10dif_mutex); 38 return 0; 39 } 40 new = crypto_alloc_shash("crct10dif", 0, 0); 41 if (IS_ERR(new)) { 42 mutex_unlock(&crc_t10dif_mutex); 43 return 0; 44 } 45 rcu_assign_pointer(crct10dif_tfm, new); 46 mutex_unlock(&crc_t10dif_mutex); 47 48 synchronize_rcu(); 49 crypto_free_shash(old); 50 return 0; 51 } 52 53 static struct notifier_block crc_t10dif_nb = { 54 .notifier_call = crc_t10dif_rehash, 55 }; 56 57 __u16 crc_t10dif_update(__u16 crc, const unsigned char *buffer, size_t len) 58 { 59 struct { 60 struct shash_desc shash; 61 char ctx[2]; 62 } desc; 63 int err; 64 65 if (static_key_false(&crct10dif_fallback)) 66 return crc_t10dif_generic(crc, buffer, len); 67 68 rcu_read_lock(); 69 desc.shash.tfm = rcu_dereference(crct10dif_tfm); 70 *(__u16 *)desc.ctx = crc; 71 72 err = crypto_shash_update(&desc.shash, buffer, len); 73 rcu_read_unlock(); 74 75 BUG_ON(err); 76 77 return *(__u16 *)desc.ctx; 78 } 79 EXPORT_SYMBOL(crc_t10dif_update); 80 81 __u16 crc_t10dif(const unsigned char *buffer, size_t len) 82 { 83 return crc_t10dif_update(0, buffer, len); 84 } 85 EXPORT_SYMBOL(crc_t10dif); 86 87 static int __init crc_t10dif_mod_init(void) 88 { 89 crypto_register_notifier(&crc_t10dif_nb); 90 crct10dif_tfm = crypto_alloc_shash("crct10dif", 0, 0); 91 if (IS_ERR(crct10dif_tfm)) { 92 static_key_slow_inc(&crct10dif_fallback); 93 crct10dif_tfm = NULL; 94 } 95 return 0; 96 } 97 98 static void __exit crc_t10dif_mod_fini(void) 99 { 100 crypto_unregister_notifier(&crc_t10dif_nb); 101 crypto_free_shash(crct10dif_tfm); 102 } 103 104 module_init(crc_t10dif_mod_init); 105 module_exit(crc_t10dif_mod_fini); 106 107 static int crc_t10dif_transform_show(char *buffer, const struct kernel_param *kp) 108 { 109 if (static_key_false(&crct10dif_fallback)) 110 return sprintf(buffer, "fallback\n"); 111 112 return sprintf(buffer, "%s\n", 113 crypto_tfm_alg_driver_name(crypto_shash_tfm(crct10dif_tfm))); 114 } 115 116 module_param_call(transform, NULL, crc_t10dif_transform_show, NULL, 0644); 117 118 MODULE_DESCRIPTION("T10 DIF CRC calculation"); 119 MODULE_LICENSE("GPL"); 120 MODULE_SOFTDEP("pre: crct10dif"); 121