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");