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(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, type: 0, mask: 0); |
44 | if (IS_ERR(ptr: new)) { |
45 | mutex_unlock(lock: &crc_t10dif_mutex); |
46 | return; |
47 | } |
48 | rcu_assign_pointer(crct10dif_tfm, new); |
49 | mutex_unlock(lock: &crc_t10dif_mutex); |
50 | |
51 | if (old) { |
52 | synchronize_rcu(); |
53 | crypto_free_shash(tfm: 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: &desc.shash, data: 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(nb: &crc_t10dif_nb); |
96 | crc_t10dif_rehash(work: &crct10dif_rehash_work); |
97 | return 0; |
98 | } |
99 | |
100 | static void __exit crc_t10dif_mod_fini(void) |
101 | { |
102 | crypto_unregister_notifier(nb: &crc_t10dif_nb); |
103 | cancel_work_sync(work: &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(buf: buffer, fmt: "fallback\n" ); |
117 | |
118 | rcu_read_lock(); |
119 | tfm = rcu_dereference(crct10dif_tfm); |
120 | len = snprintf(buf: buffer, PAGE_SIZE, fmt: "%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 | |