[Skiboot] [PATCH v4 04/11] doc: add opal secure variable documentation
Eric Richter
erichte at linux.ibm.com
Sat Oct 26 20:45:46 AEDT 2019
This patch contains the work-in-progress documentation for the
secure variable design in OPAL. Future revisions of this patch
set will (hopefully) add new pieces of documentation here.
V3:
- removed metadata
- removed get_size
- updated _get semantics for size queries
- added/expanded device tree properties
V4:
- updated for new device tree changes
Signed-off-by: Eric Richter <erichte at linux.ibm.com>
---
doc/device-tree/ibm,secureboot.rst | 10 ++
doc/device-tree/secvar.rst | 84 +++++++++++++
doc/opal-api/opal-secvar.rst | 192 +++++++++++++++++++++++++++++
3 files changed, 286 insertions(+)
create mode 100644 doc/device-tree/secvar.rst
create mode 100644 doc/opal-api/opal-secvar.rst
diff --git a/doc/device-tree/ibm,secureboot.rst b/doc/device-tree/ibm,secureboot.rst
index 42c4ed7d..b4729a9d 100644
--- a/doc/device-tree/ibm,secureboot.rst
+++ b/doc/device-tree/ibm,secureboot.rst
@@ -21,6 +21,13 @@ Required properties
It described by the ibm,cvc child
node.
+ ibm,secureboot-v3 : The container-verification-code
+ is stored in a reserved memory.
+ It described by the ibm,cvc child
+ node. Secure variables are
+ supported. `secvar` node should
+ be created.
+
secure-enabled: this property exists when the firmware stack is booting
in secure mode (hardware secure boot jumper asserted).
@@ -33,6 +40,9 @@ Required properties
hw-key-hash-size: hw-key-hash size
+ secvar: this node is created if the platform supports secure
+ variables. Contains information about the current
+ secvar status, see 'secvar.rst'.
Obsolete properties
-------------------
diff --git a/doc/device-tree/secvar.rst b/doc/device-tree/secvar.rst
new file mode 100644
index 00000000..ddf15b38
--- /dev/null
+++ b/doc/device-tree/secvar.rst
@@ -0,0 +1,84 @@
+.. _device-tree/ibm,opal/secvar:
+
+secvar
+======
+
+The ``secvar`` node provides secure variable information for the secure
+boot of the target OS.
+
+Required properties
+-------------------
+
+.. code-block:: none
+
+ status: set to "fail" if the secure variables could not
+ be initialized, validated, or some other
+ hardware problem.
+
+ update-status: contains the return code of the update queue
+ process run during initialization. Signifies if
+ updates were processed or not, and if there was
+ an error. See table below.
+ TODO: This probably belongs in the backend node.
+
+ os-secure-enforcing: If this property exists, the system is in
+ considered to be in "OS secure mode". Kexec
+ images should be signature checked, etc.
+
+ backend: This node contains any backend-specific
+ information, and is maintained by the backend driver.
+
+ storage: This node contains any storage-specific
+ information, and is mainted by the storage driver.
+
+ max-var-size: This property must be exposed as a child of the
+ storage driver, and determines how large a
+ variable can be.
+
+Example
+-------
+
+.. code-block:: dts
+
+ secvar {
+ compatible = "ibm,secvar-v1";
+ status = "okay";
+ os-secure-enforcing = <0x0>;
+ update-status = <0x0>;
+ storage {
+ compatible = "ibm,secboot-tpm-v1";
+ status = "okay";
+ max-var-size = <0x1000>;
+ }
+ backend {
+ compatible = "ibm,edk2-compat-v1";
+ status = "okay";
+ }
+ };
+
+Update Status
+-------------
+
+The update status property should be set by the backend driver to a value
+that best fits its error condition. The following table defines the
+general intent of each error code, check backend specific documentation
+for more detail.
+
++-----------------+-----------------------------------------------+
+| update-status | Generic Reason |
++-----------------|-----------------------------------------------+
+| OPAL_SUCCESS | Updates were found and processed successfully |
++-----------------|-----------------------------------------------+
+| OPAL_EMPTY | No updates were found, none processed |
++-----------------|-----------------------------------------------+
+| OPAL_PARAMETER | Unable to parse data in the update section |
++-----------------|-----------------------------------------------+
+| OPAL_PERMISSION | Update failed to apply, possible auth failure |
++-----------------|-----------------------------------------------+
+| OPAL_HARDWARE | Misc. storage-related error |
++-----------------|-----------------------------------------------+
+| OPAL_RESOURCE | Out of space (somewhere) |
++-----------------|-----------------------------------------------+
+| OPAL_NO_MEM | Out of memory |
++-----------------+-----------------------------------------------+
+
diff --git a/doc/opal-api/opal-secvar.rst b/doc/opal-api/opal-secvar.rst
new file mode 100644
index 00000000..f07c570a
--- /dev/null
+++ b/doc/opal-api/opal-secvar.rst
@@ -0,0 +1,192 @@
+OPAL Secure Variable API
+========================
+
+Overview
+--------
+
+In order to support host OS secure boot on POWER systems, the platform needs
+some form of tamper-resistant persistant storage for authorized public keys.
+Furthermore, these keys must be retrieveable by the host kernel, and new
+keys must be able to be submitted.
+
+OPAL exposes an abstracted "variable" API, in which these keys can be stored
+and retrieved. At a high level, ``opal_secvar_get`` retrieves a specific
+variable corresponding to a particular key. ``opal_secvar_get_next`` can be
+used to iterate through the keys of the stored variables.
+``opal_secvar_enqueue_update`` can be used to submit a new variable for
+processing on next boot.
+
+OPAL_SECVAR_GET
+===============
+::
+
+ #define OPAL_SECVAR_GET 176
+
+``OPAL_SECVAR_GET`` call retrieves a data blob associated with the supplied
+key.
+
+
+Parameters
+----------
+::
+
+ char *key
+ uint64_t key_len
+ void *data
+ uint64_t *data_size
+
+``key``
+ a buffer used to associate with the variable data. May
+be any encoding, but must not be all zeroes
+
+``key_len``
+ size of the key buffer in bytes
+
+``data``
+ return buffer to store the data blob of the requested variable if
+a match was found. May be set to NULL to only query the size into
+``data_size``
+
+``data_size``
+ reference to the size of the ``data`` buffer. OPAL sets this to
+the size of the requested variable if found.
+
+
+Return Values
+-------------
+
+``OPAL_SUCCESS``
+ the requested data blob was copied successfully. ``data`` was NULL,
+and the ``data_size`` value was set successfully
+
+``OPAL_PARAMETER``
+ ``key`` is NULL.
+ ``key_len`` is zero.
+ ``data_size`` is NULL.
+
+``OPAL_EMPTY``
+ no variable with the supplied ``key`` was found
+
+``OPAL_PARTIAL``
+ the buffer size provided in ``data_size`` was insufficient.
+``data_size`` is set to the minimum required size.
+
+``OPAL_UNSUPPORTED``
+ secure variables are not supported by the platform
+
+``OPAL_RESOURCE``
+ secure variables are supported, but did not initialize properly
+
+OPAL_SECVAR_GET_NEXT
+====================
+::
+
+ #define OPAL_SECVAR_GET_NEXT 177
+
+``OPAL_SECVAR_GET_NEXT`` returns the key of the next variable in the secure
+variable bank in sequence.
+
+Parameters
+----------
+::
+
+ char *key
+ uint64_t *key_len
+ uint64_t key_buf_size
+
+
+``key``
+ name of the previous variable or empty. The key of the next
+variable in sequence will be copied to ``key``. If passed as empty,
+returns the first variable in the bank
+
+``key_len``
+ length in bytes of the key in the ``key`` buffer. OPAL sets
+this to the length in bytes of the next variable in sequence
+
+``key_buf_size``
+ maximum size of the ``key`` buffer. The next key will not be
+copied if this value is less than the length of the next key
+
+
+Return Values
+-------------
+
+``OPAL_SUCCESS``
+ the key and length of the next variable in sequence was copied
+successfully
+
+``OPAL_PARAMETER``
+ ``key`` or ``key_length`` is NULL.
+ ``key_size`` is zero.
+ ``key_length`` is impossibly large. No variable with the associated
+``key`` was found
+
+``OPAL_EMPTY``
+ end of list reached
+
+``OPAL_PARTIAL``
+ the size specified in ``key_size`` is insufficient for the next
+variable's key length. ``key_length`` is set to the next variable's
+length, but ``key`` is untouched
+
+``OPAL_UNSUPPORTED``
+ secure variables are not supported by the platform
+
+``OPAL_RESOURCE``
+ secure variables are supported, but did not initialize properly
+
+OPAL_SECVAR_ENQUEUE_UPDATE
+==========================
+::
+
+ #define OPAL_SECVAR_ENQUEUE_UPDATE 178
+
+``OPAL_SECVAR_ENQUEUE`` call appends the supplied variable data to the
+queue for processing on next boot.
+
+Parameters
+----------
+::
+
+ char *key
+ uint64_t key_len
+ void *data
+ uint64_t data_size
+
+``key``
+ a buffer used to associate with the variable data. May
+be any encoding, but must not be all zeroes
+
+``key_len``
+ size of the key buffer in bytes
+
+``data``
+ buffer containing the blob of data to enqueue
+
+``data_size``
+ size of the ``data`` buffer
+
+Return Values
+-------------
+
+``OPAL_SUCCESS``
+ the variable was appended to the update queue bank successfully
+
+``OPAL_PARAMETER``
+ ``key`` or ``data`` was NULL.
+ ``key`` was empty.
+ ``key_len`` or ``data_size`` was zero.
+ ``key_len``, ``data_size`` is larger than the maximum size
+
+``OPAL_NO_MEM``
+ OPAL was unable to allocate memory for the variable update
+
+``OPAL_HARDWARE``
+ OPAL was unable to write the update to persistant storage
+
+``OPAL_UNSUPPORTED``
+ secure variables are not supported by the platform
+
+``OPAL_RESOURCE``
+ secure variables are supported, but did not initialize properly
--
2.21.0
More information about the Skiboot
mailing list