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 
crc64_rocksoft_notify(struct notifier_block * self,unsigned long val,void * data)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 
crc64_rocksoft_rehash(struct work_struct * work)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 
crc64_rocksoft_update(u64 crc,const unsigned char * buffer,size_t len)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 
crc64_rocksoft(const unsigned char * buffer,size_t len)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 
crc64_rocksoft_mod_init(void)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 
crc64_rocksoft_mod_fini(void)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 
crc64_rocksoft_transform_show(char * buffer,const struct kernel_param * kp)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