The following warning:

    ACPI0012:00: security event setup failed: -19

...is meant to capture exceptional failures of sysfs_get_dirent(),
however it will also fail in the common case when security support is
disabled. A few issues:

1/ A dev_warn() report for a common case is too chatty
2/ The setup of this notifier is generic, no need for it to be driven
   from the nfit driver, it can exist completely in the core.
3/ If it fails for any reason besides security support being disabled,
   that's fatal and should abort DIMM activation. Userspace may hang if
   it never gets overwrite notifications.
4/ The dirent needs to be released.

Move the call to the core 'dimm' driver, make it conditional on security
support being active, make it fatal for the exceptional case, add the
missing sysfs_put() at device disable time.

Fixes: 7d988097c546 ("...Add security DSM overwrite support")
Reviewed-by: Dave Jiang <dave.jiang@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

Kees reports a crash with the following signature...

 RIP: 0010:nvdimm_visible+0x79/0x80
 [..]
 Call Trace:
  internal_create_group+0xf4/0x380
  sysfs_create_groups+0x46/0xb0
  device_add+0x331/0x680
  nd_async_device_register+0x15/0x60
  async_run_entry_fn+0x38/0x100

...when starting a QEMU environment with "label-less" DIMM. Without
labels QEMU does not publish any DSM methods. Without defined methods
the NVDIMM_FAMILY type is not established and the nfit driver will skip
registering security operations.

In that case the security state should be initialized to a negative
value in __nvdimm_create() and nvdimm_visible() should skip
interrogating the specific ops. However, since 'enum
nvdimm_security_state' was only defined to contain positive values the
"if (nvdimm->sec.state < 0)" check always fails.

Define a negative error state to allow negative state values to be
handled as expected.

Fixes: f2989396553a ("acpi/nfit, libnvdimm: Introduce nvdimm_security_ops")
Reviewed-by: Dave Jiang <dave.jiang@intel.com>
Reported-by: Kees Cook <keescook@chromium.org>
Tested-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

With Intel DSM 1.8 [1] two new security DSMs are introduced. Enable/update
master passphrase and master secure erase. The master passphrase allows
a secure erase to be performed without the user passphrase that is set on
the NVDIMM. The commands of master_update and master_erase are added to
the sysfs knob in order to initiate the DSMs. They are similar in opeartion
mechanism compare to update and erase.

[1]: http://pmem.io/documents/NVDIMM_DSM_Interface-V1.8.pdf

Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

Add support for the NVDIMM_FAMILY_INTEL "ovewrite" capability as
described by the Intel DSM spec v1.7. This will allow triggering of
overwrite on Intel NVDIMMs. The overwrite operation can take tens of
minutes. When the overwrite DSM is issued successfully, the NVDIMMs will
be unaccessible. The kernel will do backoff polling to detect when the
overwrite process is completed. According to the DSM spec v1.7, the 128G
NVDIMMs can take up to 15mins to perform overwrite and larger DIMMs will
take longer.

Given that overwrite puts the DIMM in an indeterminate state until it
completes introduce the NDD_SECURITY_OVERWRITE flag to prevent other
operations from executing when overwrite is happening. The
NDD_WORK_PENDING flag is added to denote that there is a device reference
on the nvdimm device for an async workqueue thread context.

Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

Add support to issue a secure erase DSM to the Intel nvdimm. The
required passphrase is acquired from an encrypted key in the kernel user
keyring. To trigger the action, "erase <keyid>" is written to the
"security" sysfs attribute.

Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

Add support to disable passphrase (security) for the Intel nvdimm. The
passphrase used for disabling is pulled from an encrypted-key in the kernel
user keyring. The action is triggered by writing "disable <keyid>" to the
sysfs attribute "security".

Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

Add support to unlock the dimm via the kernel key management APIs. The
passphrase is expected to be pulled from userspace through keyutils.
The key management and sysfs attributes are libnvdimm generic.

Encrypted keys are used to protect the nvdimm passphrase at rest. The
master key can be a trusted-key sealed in a TPM, preferred, or an
encrypted-key, more flexible, but more exposure to a potential attacker.

Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Co-developed-by: Dan Williams <dan.j.williams@intel.com>
Reported-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

Add support for freeze security on Intel nvdimm. This locks out any
changes to security for the DIMM until a hard reset of the DIMM is
performed. This is triggered by writing "freeze" to the generic
nvdimm/nmemX "security" sysfs attribute.

Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Co-developed-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

Some NVDIMMs, like the ones defined by the NVDIMM_FAMILY_INTEL command
set, expose a security capability to lock the DIMMs at poweroff and
require a passphrase to unlock them. The security model is derived from
ATA security. In anticipation of other DIMMs implementing a similar
scheme, and to abstract the core security implementation away from the
device-specific details, introduce nvdimm_security_ops.

Initially only a status retrieval operation, ->state(), is defined,
along with the base infrastructure and definitions for future
operations.

Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Co-developed-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

The generated dimm id is needed for the sysfs attribute as well as being
used as the identifier/description for the security key. Since it's
constant and should never change, store it as a member of struct nvdimm.

As nvdimm_create() continues to grow parameters relative to NFIT driver
requirements, do not require other implementations to keep pace.
Introduce __nvdimm_create() to carry the new parameters and keep
nvdimm_create() with the long standing default api.

Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>