1 files changed, 131 insertions, 0 deletions
diff --git a/lib/crc-t10dif.c b/lib/crc-t10dif.c
new file mode 100644
index 000000000..1ed2ed487
--- /dev/null
+++ b/lib/crc-t10dif.c
@@ -0,0 +1,131 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * T10 Data Integrity Field CRC16 calculation
+ *
+ * Copyright (c) 2007 Oracle Corporation.  All rights reserved.
+ * Written by Martin K. Petersen <martin.petersen@oracle.com>
+ */
+
+#include <linux/types.h>
+#include <linux/module.h>
+#include <linux/crc-t10dif.h>
+#include <linux/err.h>
+#include <linux/init.h>
+#include <crypto/hash.h>
+#include <crypto/algapi.h>
+#include <linux/static_key.h>
+#include <linux/notifier.h>
+
+static struct crypto_shash __rcu *crct10dif_tfm;
+static DEFINE_STATIC_KEY_TRUE(crct10dif_fallback);
+static DEFINE_MUTEX(crc_t10dif_mutex);
+static struct work_struct crct10dif_rehash_work;
+
+static int crc_t10dif_notify(struct notifier_block *self, unsigned long val, void *data)
+{
+	struct crypto_alg *alg = data;
+
+	if (val != CRYPTO_MSG_ALG_LOADED ||
+	    strcmp(alg->cra_name, CRC_T10DIF_STRING))
+		return NOTIFY_DONE;
+
+	schedule_work(&crct10dif_rehash_work);
+	return NOTIFY_OK;
+}
+
+static void crc_t10dif_rehash(struct work_struct *work)
+{
+	struct crypto_shash *new, *old;
+
+	mutex_lock(&crc_t10dif_mutex);
+	old = rcu_dereference_protected(crct10dif_tfm,
+					lockdep_is_held(&crc_t10dif_mutex));
+	new = crypto_alloc_shash(CRC_T10DIF_STRING, 0, 0);
+	if (IS_ERR(new)) {
+		mutex_unlock(&crc_t10dif_mutex);
+		return;
+	}
+	rcu_assign_pointer(crct10dif_tfm, new);
+	mutex_unlock(&crc_t10dif_mutex);
+
+	if (old) {
+		synchronize_rcu();
+		crypto_free_shash(old);
+	} else {
+		static_branch_disable(&crct10dif_fallback);
+	}
+}
+
+static struct notifier_block crc_t10dif_nb = {
+	.notifier_call = crc_t10dif_notify,
+};
+
+__u16 crc_t10dif_update(__u16 crc, const unsigned char *buffer, size_t len)
+{
+	struct {
+		struct shash_desc shash;
+		__u16 crc;
+	} desc;
+	int err;
+
+	if (static_branch_unlikely(&crct10dif_fallback))
+		return crc_t10dif_generic(crc, buffer, len);
+
+	rcu_read_lock();
+	desc.shash.tfm = rcu_dereference(crct10dif_tfm);
+	desc.crc = crc;
+	err = crypto_shash_update(&desc.shash, buffer, len);
+	rcu_read_unlock();
+
+	BUG_ON(err);
+
+	return desc.crc;
+}
+EXPORT_SYMBOL(crc_t10dif_update);
+
+__u16 crc_t10dif(const unsigned char *buffer, size_t len)
+{
+	return crc_t10dif_update(0, buffer, len);
+}
+EXPORT_SYMBOL(crc_t10dif);
+
+static int __init crc_t10dif_mod_init(void)
+{
+	INIT_WORK(&crct10dif_rehash_work, crc_t10dif_rehash);
+	crypto_register_notifier(&crc_t10dif_nb);
+	crc_t10dif_rehash(&crct10dif_rehash_work);
+	return 0;
+}
+
+static void __exit crc_t10dif_mod_fini(void)
+{
+	crypto_unregister_notifier(&crc_t10dif_nb);
+	cancel_work_sync(&crct10dif_rehash_work);
+	crypto_free_shash(rcu_dereference_protected(crct10dif_tfm, 1));
+}
+
+module_init(crc_t10dif_mod_init);
+module_exit(crc_t10dif_mod_fini);
+
+static int crc_t10dif_transform_show(char *buffer, const struct kernel_param *kp)
+{
+	struct crypto_shash *tfm;
+	int len;
+
+	if (static_branch_unlikely(&crct10dif_fallback))
+		return sprintf(buffer, "fallback\n");
+
+	rcu_read_lock();
+	tfm = rcu_dereference(crct10dif_tfm);
+	len = snprintf(buffer, PAGE_SIZE, "%s\n",
+		       crypto_shash_driver_name(tfm));
+	rcu_read_unlock();
+
+	return len;
+}
+
+module_param_call(transform, NULL, crc_t10dif_transform_show, NULL, 0444);
+
+MODULE_DESCRIPTION("T10 DIF CRC calculation (library API)");
+MODULE_LICENSE("GPL");
+MODULE_SOFTDEP("pre: crct10dif");