Keith Busch | f3813f4b | 2022-03-03 12:13:10 -0800 | [diff] [blame] | 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"); |