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
13static struct crypto_shash __rcu *crc64_rocksoft_tfm;
14static DEFINE_STATIC_KEY_TRUE(crc64_rocksoft_fallback);
15static DEFINE_MUTEX(crc64_rocksoft_mutex);
16static struct work_struct crc64_rocksoft_rehash_work;
17
18static 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
30static 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
53static struct notifier_block crc64_rocksoft_nb = {
54	.notifier_call = crc64_rocksoft_notify,
55};
56
57u64 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}
78EXPORT_SYMBOL_GPL(crc64_rocksoft_update);
79
80u64 crc64_rocksoft(const unsigned char *buffer, size_t len)
81{
82	return crc64_rocksoft_update(0, buffer, len);
83}
84EXPORT_SYMBOL_GPL(crc64_rocksoft);
85
86static 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
94static 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
101module_init(crc64_rocksoft_mod_init);
102module_exit(crc64_rocksoft_mod_fini);
103
104static 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
121module_param_call(transform, NULL, crc64_rocksoft_transform_show, NULL, 0444);
122
123MODULE_AUTHOR("Keith Busch <kbusch@kernel.org>");
124MODULE_DESCRIPTION("Rocksoft model CRC64 calculation (library API)");
125MODULE_LICENSE("GPL");
126MODULE_SOFTDEP("pre: crc64");
127