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https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
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bc4f2199ca
An attempt to freeze DIMMs currently runs afoul of default blocking of all security operations in the entry to the 'store' routine for the 'security' sysfs attribute. The blanket blocking of all security operations while the DIMM is in active use in a region is too restrictive. The only security operations that need to be aware of the ->busy state are those that mutate the state of data, i.e. erase and overwrite. Refactor the ->busy checks to be applied at the entry common entry point in __security_store() rather than each of the helper routines to enable freeze to be run regardless of busy state. Reviewed-by: Dave Jiang <dave.jiang@intel.com> Reviewed-by: Jeff Moyer <jmoyer@redhat.com> Link: https://lore.kernel.org/r/156686729996.184120.3458026302402493937.stgit@dwillia2-desk3.amr.corp.intel.com Signed-off-by: Dan Williams <dan.j.williams@intel.com>
467 lines
11 KiB
C
467 lines
11 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/* Copyright(c) 2018 Intel Corporation. All rights reserved. */
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#include <linux/module.h>
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#include <linux/device.h>
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#include <linux/ndctl.h>
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#include <linux/slab.h>
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#include <linux/io.h>
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#include <linux/mm.h>
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#include <linux/cred.h>
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#include <linux/key.h>
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#include <linux/key-type.h>
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#include <keys/user-type.h>
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#include <keys/encrypted-type.h>
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#include "nd-core.h"
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#include "nd.h"
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#define NVDIMM_BASE_KEY 0
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#define NVDIMM_NEW_KEY 1
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static bool key_revalidate = true;
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module_param(key_revalidate, bool, 0444);
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MODULE_PARM_DESC(key_revalidate, "Require key validation at init.");
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static const char zero_key[NVDIMM_PASSPHRASE_LEN];
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static void *key_data(struct key *key)
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{
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struct encrypted_key_payload *epayload = dereference_key_locked(key);
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lockdep_assert_held_read(&key->sem);
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return epayload->decrypted_data;
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}
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static void nvdimm_put_key(struct key *key)
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{
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if (!key)
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return;
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up_read(&key->sem);
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key_put(key);
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}
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/*
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* Retrieve kernel key for DIMM and request from user space if
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* necessary. Returns a key held for read and must be put by
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* nvdimm_put_key() before the usage goes out of scope.
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*/
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static struct key *nvdimm_request_key(struct nvdimm *nvdimm)
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{
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struct key *key = NULL;
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static const char NVDIMM_PREFIX[] = "nvdimm:";
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char desc[NVDIMM_KEY_DESC_LEN + sizeof(NVDIMM_PREFIX)];
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struct device *dev = &nvdimm->dev;
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sprintf(desc, "%s%s", NVDIMM_PREFIX, nvdimm->dimm_id);
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key = request_key(&key_type_encrypted, desc, "");
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if (IS_ERR(key)) {
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if (PTR_ERR(key) == -ENOKEY)
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dev_dbg(dev, "request_key() found no key\n");
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else
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dev_dbg(dev, "request_key() upcall failed\n");
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key = NULL;
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} else {
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struct encrypted_key_payload *epayload;
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down_read(&key->sem);
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epayload = dereference_key_locked(key);
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if (epayload->decrypted_datalen != NVDIMM_PASSPHRASE_LEN) {
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up_read(&key->sem);
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key_put(key);
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key = NULL;
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}
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}
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return key;
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}
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static const void *nvdimm_get_key_payload(struct nvdimm *nvdimm,
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struct key **key)
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{
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*key = nvdimm_request_key(nvdimm);
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if (!*key)
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return zero_key;
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return key_data(*key);
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}
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static struct key *nvdimm_lookup_user_key(struct nvdimm *nvdimm,
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key_serial_t id, int subclass)
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{
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key_ref_t keyref;
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struct key *key;
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struct encrypted_key_payload *epayload;
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struct device *dev = &nvdimm->dev;
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keyref = lookup_user_key(id, 0, 0);
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if (IS_ERR(keyref))
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return NULL;
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key = key_ref_to_ptr(keyref);
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if (key->type != &key_type_encrypted) {
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key_put(key);
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return NULL;
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}
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dev_dbg(dev, "%s: key found: %#x\n", __func__, key_serial(key));
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down_read_nested(&key->sem, subclass);
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epayload = dereference_key_locked(key);
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if (epayload->decrypted_datalen != NVDIMM_PASSPHRASE_LEN) {
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up_read(&key->sem);
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key_put(key);
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key = NULL;
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}
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return key;
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}
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static const void *nvdimm_get_user_key_payload(struct nvdimm *nvdimm,
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key_serial_t id, int subclass, struct key **key)
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{
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*key = NULL;
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if (id == 0) {
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if (subclass == NVDIMM_BASE_KEY)
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return zero_key;
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else
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return NULL;
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}
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*key = nvdimm_lookup_user_key(nvdimm, id, subclass);
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if (!*key)
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return NULL;
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return key_data(*key);
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}
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static int nvdimm_key_revalidate(struct nvdimm *nvdimm)
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{
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struct key *key;
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int rc;
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const void *data;
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if (!nvdimm->sec.ops->change_key)
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return -EOPNOTSUPP;
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data = nvdimm_get_key_payload(nvdimm, &key);
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/*
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* Send the same key to the hardware as new and old key to
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* verify that the key is good.
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*/
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rc = nvdimm->sec.ops->change_key(nvdimm, data, data, NVDIMM_USER);
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if (rc < 0) {
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nvdimm_put_key(key);
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return rc;
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}
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nvdimm_put_key(key);
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nvdimm->sec.flags = nvdimm_security_flags(nvdimm, NVDIMM_USER);
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return 0;
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}
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static int __nvdimm_security_unlock(struct nvdimm *nvdimm)
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{
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struct device *dev = &nvdimm->dev;
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struct nvdimm_bus *nvdimm_bus = walk_to_nvdimm_bus(dev);
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struct key *key;
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const void *data;
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int rc;
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/* The bus lock should be held at the top level of the call stack */
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lockdep_assert_held(&nvdimm_bus->reconfig_mutex);
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if (!nvdimm->sec.ops || !nvdimm->sec.ops->unlock
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|| !nvdimm->sec.flags)
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return -EIO;
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if (test_bit(NDD_SECURITY_OVERWRITE, &nvdimm->flags)) {
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dev_dbg(dev, "Security operation in progress.\n");
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return -EBUSY;
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}
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/*
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* If the pre-OS has unlocked the DIMM, attempt to send the key
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* from request_key() to the hardware for verification. Failure
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* to revalidate the key against the hardware results in a
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* freeze of the security configuration. I.e. if the OS does not
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* have the key, security is being managed pre-OS.
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*/
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if (test_bit(NVDIMM_SECURITY_UNLOCKED, &nvdimm->sec.flags)) {
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if (!key_revalidate)
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return 0;
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return nvdimm_key_revalidate(nvdimm);
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} else
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data = nvdimm_get_key_payload(nvdimm, &key);
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rc = nvdimm->sec.ops->unlock(nvdimm, data);
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dev_dbg(dev, "key: %d unlock: %s\n", key_serial(key),
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rc == 0 ? "success" : "fail");
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nvdimm_put_key(key);
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nvdimm->sec.flags = nvdimm_security_flags(nvdimm, NVDIMM_USER);
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return rc;
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}
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int nvdimm_security_unlock(struct device *dev)
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{
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struct nvdimm *nvdimm = to_nvdimm(dev);
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int rc;
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nvdimm_bus_lock(dev);
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rc = __nvdimm_security_unlock(nvdimm);
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nvdimm_bus_unlock(dev);
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return rc;
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}
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static int check_security_state(struct nvdimm *nvdimm)
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{
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struct device *dev = &nvdimm->dev;
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if (test_bit(NVDIMM_SECURITY_FROZEN, &nvdimm->sec.flags)) {
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dev_dbg(dev, "Incorrect security state: %#lx\n",
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nvdimm->sec.flags);
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return -EIO;
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}
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if (test_bit(NDD_SECURITY_OVERWRITE, &nvdimm->flags)) {
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dev_dbg(dev, "Security operation in progress.\n");
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return -EBUSY;
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}
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return 0;
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}
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int nvdimm_security_disable(struct nvdimm *nvdimm, unsigned int keyid)
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{
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struct device *dev = &nvdimm->dev;
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struct nvdimm_bus *nvdimm_bus = walk_to_nvdimm_bus(dev);
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struct key *key;
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int rc;
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const void *data;
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/* The bus lock should be held at the top level of the call stack */
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lockdep_assert_held(&nvdimm_bus->reconfig_mutex);
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if (!nvdimm->sec.ops || !nvdimm->sec.ops->disable
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|| !nvdimm->sec.flags)
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return -EOPNOTSUPP;
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rc = check_security_state(nvdimm);
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if (rc)
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return rc;
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data = nvdimm_get_user_key_payload(nvdimm, keyid,
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NVDIMM_BASE_KEY, &key);
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if (!data)
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return -ENOKEY;
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rc = nvdimm->sec.ops->disable(nvdimm, data);
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dev_dbg(dev, "key: %d disable: %s\n", key_serial(key),
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rc == 0 ? "success" : "fail");
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nvdimm_put_key(key);
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nvdimm->sec.flags = nvdimm_security_flags(nvdimm, NVDIMM_USER);
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return rc;
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}
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int nvdimm_security_update(struct nvdimm *nvdimm, unsigned int keyid,
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unsigned int new_keyid,
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enum nvdimm_passphrase_type pass_type)
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{
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struct device *dev = &nvdimm->dev;
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struct nvdimm_bus *nvdimm_bus = walk_to_nvdimm_bus(dev);
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struct key *key, *newkey;
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int rc;
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const void *data, *newdata;
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/* The bus lock should be held at the top level of the call stack */
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lockdep_assert_held(&nvdimm_bus->reconfig_mutex);
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if (!nvdimm->sec.ops || !nvdimm->sec.ops->change_key
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|| !nvdimm->sec.flags)
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return -EOPNOTSUPP;
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rc = check_security_state(nvdimm);
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if (rc)
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return rc;
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data = nvdimm_get_user_key_payload(nvdimm, keyid,
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NVDIMM_BASE_KEY, &key);
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if (!data)
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return -ENOKEY;
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newdata = nvdimm_get_user_key_payload(nvdimm, new_keyid,
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NVDIMM_NEW_KEY, &newkey);
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if (!newdata) {
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nvdimm_put_key(key);
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return -ENOKEY;
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}
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rc = nvdimm->sec.ops->change_key(nvdimm, data, newdata, pass_type);
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dev_dbg(dev, "key: %d %d update%s: %s\n",
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key_serial(key), key_serial(newkey),
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pass_type == NVDIMM_MASTER ? "(master)" : "(user)",
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rc == 0 ? "success" : "fail");
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nvdimm_put_key(newkey);
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nvdimm_put_key(key);
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if (pass_type == NVDIMM_MASTER)
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nvdimm->sec.ext_flags = nvdimm_security_flags(nvdimm,
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NVDIMM_MASTER);
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else
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nvdimm->sec.flags = nvdimm_security_flags(nvdimm,
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NVDIMM_USER);
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return rc;
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}
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int nvdimm_security_erase(struct nvdimm *nvdimm, unsigned int keyid,
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enum nvdimm_passphrase_type pass_type)
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{
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struct device *dev = &nvdimm->dev;
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struct nvdimm_bus *nvdimm_bus = walk_to_nvdimm_bus(dev);
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struct key *key = NULL;
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int rc;
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const void *data;
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/* The bus lock should be held at the top level of the call stack */
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lockdep_assert_held(&nvdimm_bus->reconfig_mutex);
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if (!nvdimm->sec.ops || !nvdimm->sec.ops->erase
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|| !nvdimm->sec.flags)
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return -EOPNOTSUPP;
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rc = check_security_state(nvdimm);
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if (rc)
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return rc;
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if (!test_bit(NVDIMM_SECURITY_UNLOCKED, &nvdimm->sec.ext_flags)
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&& pass_type == NVDIMM_MASTER) {
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dev_dbg(dev,
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"Attempt to secure erase in wrong master state.\n");
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return -EOPNOTSUPP;
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}
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data = nvdimm_get_user_key_payload(nvdimm, keyid,
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NVDIMM_BASE_KEY, &key);
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if (!data)
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return -ENOKEY;
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rc = nvdimm->sec.ops->erase(nvdimm, data, pass_type);
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dev_dbg(dev, "key: %d erase%s: %s\n", key_serial(key),
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pass_type == NVDIMM_MASTER ? "(master)" : "(user)",
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rc == 0 ? "success" : "fail");
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nvdimm_put_key(key);
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nvdimm->sec.flags = nvdimm_security_flags(nvdimm, NVDIMM_USER);
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return rc;
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}
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int nvdimm_security_overwrite(struct nvdimm *nvdimm, unsigned int keyid)
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{
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struct device *dev = &nvdimm->dev;
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struct nvdimm_bus *nvdimm_bus = walk_to_nvdimm_bus(dev);
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struct key *key = NULL;
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int rc;
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const void *data;
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/* The bus lock should be held at the top level of the call stack */
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lockdep_assert_held(&nvdimm_bus->reconfig_mutex);
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if (!nvdimm->sec.ops || !nvdimm->sec.ops->overwrite
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|| !nvdimm->sec.flags)
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return -EOPNOTSUPP;
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if (dev->driver == NULL) {
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dev_dbg(dev, "Unable to overwrite while DIMM active.\n");
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return -EINVAL;
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}
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rc = check_security_state(nvdimm);
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if (rc)
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return rc;
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data = nvdimm_get_user_key_payload(nvdimm, keyid,
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NVDIMM_BASE_KEY, &key);
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if (!data)
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return -ENOKEY;
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rc = nvdimm->sec.ops->overwrite(nvdimm, data);
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dev_dbg(dev, "key: %d overwrite submission: %s\n", key_serial(key),
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rc == 0 ? "success" : "fail");
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nvdimm_put_key(key);
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if (rc == 0) {
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set_bit(NDD_SECURITY_OVERWRITE, &nvdimm->flags);
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set_bit(NDD_WORK_PENDING, &nvdimm->flags);
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set_bit(NVDIMM_SECURITY_OVERWRITE, &nvdimm->sec.flags);
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/*
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* Make sure we don't lose device while doing overwrite
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* query.
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*/
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get_device(dev);
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queue_delayed_work(system_wq, &nvdimm->dwork, 0);
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}
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return rc;
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}
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void __nvdimm_security_overwrite_query(struct nvdimm *nvdimm)
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{
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struct nvdimm_bus *nvdimm_bus = walk_to_nvdimm_bus(&nvdimm->dev);
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int rc;
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unsigned int tmo;
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/* The bus lock should be held at the top level of the call stack */
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lockdep_assert_held(&nvdimm_bus->reconfig_mutex);
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/*
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* Abort and release device if we no longer have the overwrite
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* flag set. It means the work has been canceled.
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*/
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if (!test_bit(NDD_WORK_PENDING, &nvdimm->flags))
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return;
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tmo = nvdimm->sec.overwrite_tmo;
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if (!nvdimm->sec.ops || !nvdimm->sec.ops->query_overwrite
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|| !nvdimm->sec.flags)
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return;
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rc = nvdimm->sec.ops->query_overwrite(nvdimm);
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if (rc == -EBUSY) {
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/* setup delayed work again */
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tmo += 10;
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queue_delayed_work(system_wq, &nvdimm->dwork, tmo * HZ);
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nvdimm->sec.overwrite_tmo = min(15U * 60U, tmo);
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return;
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}
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if (rc < 0)
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dev_dbg(&nvdimm->dev, "overwrite failed\n");
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else
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dev_dbg(&nvdimm->dev, "overwrite completed\n");
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if (nvdimm->sec.overwrite_state)
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sysfs_notify_dirent(nvdimm->sec.overwrite_state);
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nvdimm->sec.overwrite_tmo = 0;
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clear_bit(NDD_SECURITY_OVERWRITE, &nvdimm->flags);
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clear_bit(NDD_WORK_PENDING, &nvdimm->flags);
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put_device(&nvdimm->dev);
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nvdimm->sec.flags = nvdimm_security_flags(nvdimm, NVDIMM_USER);
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nvdimm->sec.flags = nvdimm_security_flags(nvdimm, NVDIMM_MASTER);
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}
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void nvdimm_security_overwrite_query(struct work_struct *work)
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{
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struct nvdimm *nvdimm =
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container_of(work, typeof(*nvdimm), dwork.work);
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nvdimm_bus_lock(&nvdimm->dev);
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__nvdimm_security_overwrite_query(nvdimm);
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nvdimm_bus_unlock(&nvdimm->dev);
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}
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