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// SPDX-License-Identifier: GPL-2.0
/* Copyright(c) 2018 Intel Corporation. All rights reserved. */
#include <linux/module.h>
#include <linux/device.h>
#include <linux/ndctl.h>
#include <linux/slab.h>
#include <linux/io.h>
#include <linux/mm.h>
#include <linux/cred.h>
#include <linux/key.h>
#include <linux/key-type.h>
#include <keys/user-type.h>
#include <keys/encrypted-type.h>
#include "nd-core.h"
#include "nd.h"
static bool key_revalidate = true;
module_param(key_revalidate, bool, 0444);
MODULE_PARM_DESC(key_revalidate, "Require key validation at init.");
static void *key_data(struct key *key)
{
struct encrypted_key_payload *epayload = dereference_key_locked(key);
lockdep_assert_held_read(&key->sem);
return epayload->decrypted_data;
}
static void nvdimm_put_key(struct key *key)
{
up_read(&key->sem);
key_put(key);
}
/*
* Retrieve kernel key for DIMM and request from user space if
* necessary. Returns a key held for read and must be put by
* nvdimm_put_key() before the usage goes out of scope.
*/
static struct key *nvdimm_request_key(struct nvdimm *nvdimm)
{
struct key *key = NULL;
static const char NVDIMM_PREFIX[] = "nvdimm:";
char desc[NVDIMM_KEY_DESC_LEN + sizeof(NVDIMM_PREFIX)];
struct device *dev = &nvdimm->dev;
sprintf(desc, "%s%s", NVDIMM_PREFIX, nvdimm->dimm_id);
key = request_key(&key_type_encrypted, desc, "");
if (IS_ERR(key)) {
if (PTR_ERR(key) == -ENOKEY)
dev_warn(dev, "request_key() found no key\n");
else
dev_warn(dev, "request_key() upcall failed\n");
key = NULL;
} else {
struct encrypted_key_payload *epayload;
down_read(&key->sem);
epayload = dereference_key_locked(key);
if (epayload->decrypted_datalen != NVDIMM_PASSPHRASE_LEN) {
up_read(&key->sem);
key_put(key);
key = NULL;
}
}
return key;
}
static struct key *nvdimm_key_revalidate(struct nvdimm *nvdimm)
{
struct key *key;
int rc;
if (!nvdimm->sec.ops->change_key)
return NULL;
key = nvdimm_request_key(nvdimm);
if (!key)
return NULL;
/*
* Send the same key to the hardware as new and old key to
* verify that the key is good.
*/
rc = nvdimm->sec.ops->change_key(nvdimm, key_data(key), key_data(key));
if (rc < 0) {
nvdimm_put_key(key);
key = NULL;
}
return key;
}
static int __nvdimm_security_unlock(struct nvdimm *nvdimm)
{
struct device *dev = &nvdimm->dev;
struct nvdimm_bus *nvdimm_bus = walk_to_nvdimm_bus(dev);
struct key *key = NULL;
int rc;
/* The bus lock should be held at the top level of the call stack */
lockdep_assert_held(&nvdimm_bus->reconfig_mutex);
if (!nvdimm->sec.ops || !nvdimm->sec.ops->unlock
|| nvdimm->sec.state < 0)
return -EIO;
/*
* If the pre-OS has unlocked the DIMM, attempt to send the key
* from request_key() to the hardware for verification. Failure
* to revalidate the key against the hardware results in a
* freeze of the security configuration. I.e. if the OS does not
* have the key, security is being managed pre-OS.
*/
if (nvdimm->sec.state == NVDIMM_SECURITY_UNLOCKED) {
if (!key_revalidate)
return 0;
key = nvdimm_key_revalidate(nvdimm);
if (!key)
return nvdimm_security_freeze(nvdimm);
} else
key = nvdimm_request_key(nvdimm);
if (!key)
return -ENOKEY;
rc = nvdimm->sec.ops->unlock(nvdimm, key_data(key));
dev_dbg(dev, "key: %d unlock: %s\n", key_serial(key),
rc == 0 ? "success" : "fail");
nvdimm_put_key(key);
nvdimm->sec.state = nvdimm_security_state(nvdimm);
return rc;
}
int nvdimm_security_unlock(struct device *dev)
{
struct nvdimm *nvdimm = to_nvdimm(dev);
int rc;
nvdimm_bus_lock(dev);
rc = __nvdimm_security_unlock(nvdimm);
nvdimm_bus_unlock(dev);
return rc;
}
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