On Thu, Jul 12, 2018 at 1:49 PM, Dave Jiang <dave.ji...@intel.com> wrote: > Add theory of operation for the security support that's going into > libnvdimm. > > Signed-off-by: Dave Jiang <dave.ji...@intel.com> > --- > Documentation/nvdimm/security | 70 > +++++++++++++++++++++++++++++++++++++++++ > 1 file changed, 70 insertions(+) > create mode 100644 Documentation/nvdimm/security >
Looks ok to me, but I don't know if there's a policy about new Documentation needing to be in rst format, or any other concerns? Adding Jon... > diff --git a/Documentation/nvdimm/security b/Documentation/nvdimm/security > new file mode 100644 > index 000000000000..b776ef1f5e41 > --- /dev/null > +++ b/Documentation/nvdimm/security > @@ -0,0 +1,70 @@ > +NVDIMM SECURITY > +=============== > + > +1. Introduction > +--------------- > + > +With the introduction of Intel DSM v1.7 specification [1], security DSMs are > +introduced. The spec added the following security DSMs: "get security state", > +"set passphrase", "disable passphrase", "unlock unit", "freeze lock", > +"secure erase", and "overwrite". A security_ops data structure has been > +added to struct dimm in order to support the security operations and generic > +APIs are exposed to allow vendor neutral operations. > + > +2. Sysfs Interface > +------------------ > +The "security" sysfs attribute is provided in the nvdimm sysfs directory. For > +example: > +/sys/devices/LNXSYSTM:00/LNXSYBUS:00/ACPI0012:00/ndbus0/nmem0/security > + > +The "show" function of that attribute will display the security state for > +that DIMM. The following states are available: disabled, unlocked, locked, > +frozen, and unsupported. > + > +The "store" function takes several commands when the attribute is written to > +in order to support some of the security functionalities: > +update - enable security. Add or update current key. > +disable - disable enabled security and remove key. > +freeze - freeze changing of security states. > +erase - generate new ecryption key for DIMM and crypto-scrambles all existing > + user data. > + > +3. Key Management > +----------------- > + > +The key is associted to the payload by the DIMM id. For example: > +# cat /sys/devices/LNXSYSTM:00/LNXSYBUS:00/ACPI0012:00/ndbus0/nmem0/nfit/id > +8089-a2-1740-00000133 > +The DIMM id would be provided along with the key payload (passphrase) to > +the kernel. > + > +The security keys are managed on the basis of a single key per DIMM. The > +key "passphrase" is expected to be 32bytes long or padded to 32bytes. This is > +similar to the ATA security specification [2]. A key is initially acquired > +via the request_key() kernel API call and retrieved from userspace. It is up > to > +the user to provide an upcall application to retrieve the key in whatever > +fashion meets their security requirements. > + > +The payload provided to the key can be a 32bytes payload or 64bytes payload > +when doing an "update". The payload is viewed as 64 bytes in the following > +format: > +[32 bytes new key data zero padded][32 bytes current key data zero padded] > +However, a 32bytes payload can be provided and will be assumed as the old > +key to be 32 bytes of 0s and the provided 32bytes payload is the new key. > +It is up to the user upcall function how that's presented as the key payload > +to the kernel. > + > +All the other security functions that require a provided key can accept a > +32bytes payload or 64bytes. If the payload is 64bytes, then second 32bytes > +will be ignored and the first 32bytes contains the expected "passphrase". > + > +4. Unlocking > +------------ > +When the DIMMs are being enumerated by the kernel, the kernel will attempt to > +retrieve the key from its keyring. If that fails, it will attempt to > +acquire the key from the userspace upcall function. This is the only time > +a locked DIMM can be unlocked. Once unlocked, the DIMM will remain unlocked > +until reboot. > + > +[1]: http://pmem.io/documents/NVDIMM_DSM_Interface-V1.7.pdf > +[2]: > http://www.t13.org/documents/UploadedDocuments/docs2006/e05179r4-ACS-SecurityClarifications.pdf > _______________________________________________ Linux-nvdimm mailing list Linux-nvdimm@lists.01.org https://lists.01.org/mailman/listinfo/linux-nvdimm
