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1 | // SPDX-License-Identifier: GPL-2.0-only |
2 | ||
3 | #include <linux/types.h> | |
4 | #include <linux/module.h> | |
5 | #include <linux/crc64.h> | |
6 | #include <linux/err.h> | |
7 | #include <linux/init.h> | |
8 | #include <crypto/hash.h> | |
9 | #include <crypto/algapi.h> | |
10 | #include <linux/static_key.h> | |
11 | #include <linux/notifier.h> | |
12 | ||
13 | static struct crypto_shash __rcu *crc64_rocksoft_tfm; | |
14 | static DEFINE_STATIC_KEY_TRUE(crc64_rocksoft_fallback); | |
15 | static DEFINE_MUTEX(crc64_rocksoft_mutex); | |
16 | static struct work_struct crc64_rocksoft_rehash_work; | |
17 | ||
18 | static int crc64_rocksoft_notify(struct notifier_block *self, unsigned long val, void *data) | |
19 | { | |
20 | struct crypto_alg *alg = data; | |
21 | ||
22 | if (val != CRYPTO_MSG_ALG_LOADED || | |
23 | strcmp(alg->cra_name, CRC64_ROCKSOFT_STRING)) | |
24 | return NOTIFY_DONE; | |
25 | ||
26 | schedule_work(&crc64_rocksoft_rehash_work); | |
27 | return NOTIFY_OK; | |
28 | } | |
29 | ||
30 | static void crc64_rocksoft_rehash(struct work_struct *work) | |
31 | { | |
32 | struct crypto_shash *new, *old; | |
33 | ||
34 | mutex_lock(&crc64_rocksoft_mutex); | |
35 | old = rcu_dereference_protected(crc64_rocksoft_tfm, | |
36 | lockdep_is_held(&crc64_rocksoft_mutex)); | |
37 | new = crypto_alloc_shash(CRC64_ROCKSOFT_STRING, 0, 0); | |
38 | if (IS_ERR(new)) { | |
39 | mutex_unlock(&crc64_rocksoft_mutex); | |
40 | return; | |
41 | } | |
42 | rcu_assign_pointer(crc64_rocksoft_tfm, new); | |
43 | mutex_unlock(&crc64_rocksoft_mutex); | |
44 | ||
45 | if (old) { | |
46 | synchronize_rcu(); | |
47 | crypto_free_shash(old); | |
48 | } else { | |
49 | static_branch_disable(&crc64_rocksoft_fallback); | |
50 | } | |
51 | } | |
52 | ||
53 | static struct notifier_block crc64_rocksoft_nb = { | |
54 | .notifier_call = crc64_rocksoft_notify, | |
55 | }; | |
56 | ||
57 | u64 crc64_rocksoft_update(u64 crc, const unsigned char *buffer, size_t len) | |
58 | { | |
59 | struct { | |
60 | struct shash_desc shash; | |
61 | u64 crc; | |
62 | } desc; | |
63 | int err; | |
64 | ||
65 | if (static_branch_unlikely(&crc64_rocksoft_fallback)) | |
66 | return crc64_rocksoft_generic(crc, buffer, len); | |
67 | ||
68 | rcu_read_lock(); | |
69 | desc.shash.tfm = rcu_dereference(crc64_rocksoft_tfm); | |
70 | desc.crc = crc; | |
71 | err = crypto_shash_update(&desc.shash, buffer, len); | |
72 | rcu_read_unlock(); | |
73 | ||
74 | BUG_ON(err); | |
75 | ||
76 | return desc.crc; | |
77 | } | |
78 | EXPORT_SYMBOL_GPL(crc64_rocksoft_update); | |
79 | ||
80 | u64 crc64_rocksoft(const unsigned char *buffer, size_t len) | |
81 | { | |
82 | return crc64_rocksoft_update(0, buffer, len); | |
83 | } | |
84 | EXPORT_SYMBOL_GPL(crc64_rocksoft); | |
85 | ||
86 | static int __init crc64_rocksoft_mod_init(void) | |
87 | { | |
88 | INIT_WORK(&crc64_rocksoft_rehash_work, crc64_rocksoft_rehash); | |
89 | crypto_register_notifier(&crc64_rocksoft_nb); | |
90 | crc64_rocksoft_rehash(&crc64_rocksoft_rehash_work); | |
91 | return 0; | |
92 | } | |
93 | ||
94 | static void __exit crc64_rocksoft_mod_fini(void) | |
95 | { | |
96 | crypto_unregister_notifier(&crc64_rocksoft_nb); | |
97 | cancel_work_sync(&crc64_rocksoft_rehash_work); | |
98 | crypto_free_shash(rcu_dereference_protected(crc64_rocksoft_tfm, 1)); | |
99 | } | |
100 | ||
101 | module_init(crc64_rocksoft_mod_init); | |
102 | module_exit(crc64_rocksoft_mod_fini); | |
103 | ||
104 | static int crc64_rocksoft_transform_show(char *buffer, const struct kernel_param *kp) | |
105 | { | |
106 | struct crypto_shash *tfm; | |
107 | int len; | |
108 | ||
109 | if (static_branch_unlikely(&crc64_rocksoft_fallback)) | |
110 | return sprintf(buffer, "fallback\n"); | |
111 | ||
112 | rcu_read_lock(); | |
113 | tfm = rcu_dereference(crc64_rocksoft_tfm); | |
114 | len = snprintf(buffer, PAGE_SIZE, "%s\n", | |
115 | crypto_shash_driver_name(tfm)); | |
116 | rcu_read_unlock(); | |
117 | ||
118 | return len; | |
119 | } | |
120 | ||
121 | module_param_call(transform, NULL, crc64_rocksoft_transform_show, NULL, 0444); | |
122 | ||
123 | MODULE_AUTHOR("Keith Busch <kbusch@kernel.org>"); | |
124 | MODULE_DESCRIPTION("Rocksoft model CRC64 calculation (library API)"); | |
125 | MODULE_LICENSE("GPL"); | |
126 | MODULE_SOFTDEP("pre: crc64"); |