[PATCH 02/11] libnvdimm: create keyring to store security keys

[Dave Jiang <dave.jiang@intel.com>]

Prepping the libnvdimm to support security management by adding a keyring
in order to provide passphrase management through the kernel key management
APIs.

Signed-off-by: Dave Jiang <dave.jiang@intel.com>
---
 drivers/nvdimm/dimm.c     |   90 +++++++++++++++++++++++++++++++++++++++++++++
 include/linux/libnvdimm.h |    5 +++
 2 files changed, 95 insertions(+)

diff --git a/drivers/nvdimm/dimm.c b/drivers/nvdimm/dimm.c
index 6c8fb7590838..ee0c68efa82a 100644
--- a/drivers/nvdimm/dimm.c
+++ b/drivers/nvdimm/dimm.c
@@ -18,9 +18,46 @@
 #include <linux/slab.h>
 #include <linux/mm.h>
 #include <linux/nd.h>
+#include <linux/cred.h>
+#include <keys/user-type.h>
+#include <linux/key-type.h>
+#include <linux/keyctl.h>
 #include "label.h"
 #include "nd.h"
 
+const struct cred *nvdimm_cred;
+static int nvdimm_key_instantiate(struct key *key,
+		struct key_preparsed_payload *prep);
+static void nvdimm_key_destroy(struct key *key);
+
+struct key_type nvdimm_key_type = {
+	.name = "nvdimm",
+	.instantiate = nvdimm_key_instantiate,
+	.destroy = nvdimm_key_destroy,
+	.describe = user_describe,
+	.def_datalen = NVDIMM_DEFAULT_PASSPHRASE_LEN * 2,
+};
+
+static int nvdimm_key_instantiate(struct key *key,
+		struct key_preparsed_payload *prep)
+{
+	char *payload;
+
+	payload = kzalloc(nvdimm_key_type.def_datalen, GFP_KERNEL);
+	if (!payload)
+		return -ENOMEM;
+
+	key->datalen = min(nvdimm_key_type.def_datalen, prep->datalen);
+	memcpy(payload, prep->data, key->datalen);
+	key->payload.data[0] = payload;
+	return 0;
+}
+
+static void nvdimm_key_destroy(struct key *key)
+{
+	kfree(key->payload.data[0]);
+}
+
 static int nvdimm_probe(struct device *dev)
 {
 	struct nvdimm_drvdata *ndd;
@@ -129,13 +166,66 @@ static struct nd_device_driver nvdimm_driver = {
 	.type = ND_DRIVER_DIMM,
 };
 
+static int nvdimm_register_keyring(void)
+{
+	struct cred *cred;
+	struct key *keyring;
+	int rc;
+
+	rc = register_key_type(&nvdimm_key_type);
+	if (rc < 0)
+		return rc;
+
+	cred = prepare_kernel_cred(NULL);
+	if (!cred) {
+		rc = -ENOMEM;
+		goto failed_cred;
+	}
+
+	keyring = keyring_alloc(".nvdimm",
+			GLOBAL_ROOT_UID, GLOBAL_ROOT_GID, cred,
+			(KEY_POS_ALL & ~KEY_POS_SETATTR) |
+			(KEY_USR_ALL & ~KEY_USR_SETATTR),
+			KEY_ALLOC_NOT_IN_QUOTA, NULL, NULL);
+	if (IS_ERR(keyring)) {
+		rc = PTR_ERR(keyring);
+		goto failed_keyring;
+	}
+
+	set_bit(KEY_FLAG_ROOT_CAN_CLEAR, &keyring->flags);
+	cred->thread_keyring = keyring;
+	cred->jit_keyring = KEY_REQKEY_DEFL_THREAD_KEYRING;
+	nvdimm_cred = cred;
+	return 0;
+
+ failed_cred:
+	unregister_key_type(&nvdimm_key_type);
+ failed_keyring:
+	put_cred(cred);
+	return rc;
+}
+
+static void nvdimm_unregister_keyring(void)
+{
+	key_revoke(nvdimm_cred->thread_keyring);
+	unregister_key_type(&nvdimm_key_type);
+	put_cred(nvdimm_cred);
+}
+
 int __init nvdimm_init(void)
 {
+	int rc;
+
+	rc = nvdimm_register_keyring();
+	if (rc < 0)
+		return rc;
+
 	return nd_driver_register(&nvdimm_driver);
 }
 
 void nvdimm_exit(void)
 {
+	nvdimm_unregister_keyring();
 	driver_unregister(&nvdimm_driver.drv);
 }
 
diff --git a/include/linux/libnvdimm.h b/include/linux/libnvdimm.h
index 472171af7f60..a250ff2a30df 100644
--- a/include/linux/libnvdimm.h
+++ b/include/linux/libnvdimm.h
@@ -155,6 +155,11 @@ static inline struct nd_blk_region_desc *to_blk_region_desc(
 
 }
 
+extern struct key_type nvdimm_key_type;
+
+#define NVDIMM_DEFAULT_PASSPHRASE_LEN		32
+#define NVDIMM_DEFAULT_DESC_LEN			32
+
 void badrange_init(struct badrange *badrange);
 int badrange_add(struct badrange *badrange, u64 addr, u64 length);
 void badrange_forget(struct badrange *badrange, phys_addr_t start,

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