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");
127
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