docs(threat-model): add a threat model for TF-A with Arm CCA
Arm Confidential Compute Architecture (Arm CCA) support, underpinned by
Arm Realm Management Extension (RME) support, brings in a few important
software and hardware architectural changes in TF-A, which warrants a
new security analysis of the code base. Results of this analysis are
captured in a new threat model document, provided in this patch.
The main changes introduced in TF-A to support Arm CCA / RME are:
- Presence of a new threat agent: realm world clients.
- Availability of Arm CCA Hardware Enforced Security (HES) to support
measured boot and trusted boot.
- Configuration of the Granule Protection Tables (GPT) for
inter-world memory protection.
This is only an initial version of the threat model and we expect to
enrich it in the future.
Signed-off-by: Sandrine Bailleux <sandrine.bailleux@arm.com>
Co-authored-by: Manish Pandey <manish.pandey2@arm.com>
Change-Id: Iab84dc724df694511508f90dc76b6d469c4cccd5
diff --git a/docs/threat_model/threat_model.rst b/docs/threat_model/threat_model.rst
index d1a77f5..0da2558 100644
--- a/docs/threat_model/threat_model.rst
+++ b/docs/threat_model/threat_model.rst
@@ -36,6 +36,9 @@
- There are no Root and Realm worlds. These are introduced by :ref:`Realm
Management Extension (RME)`.
+ The :ref:`Threat Model for TF-A with Arm CCA support` covers these types of
+ configurations.
+
- No experimental features are enabled. We do not consider threats that may come
from them.
@@ -274,6 +277,8 @@
them. To help developers implement mitigations in the right place, threats below
are categorized based on the firmware image that should mitigate them.
+.. _General Threats:
+
General Threats for All Firmware Images
---------------------------------------
@@ -608,6 +613,8 @@
+------------------------+-----------------------------------------------------+
+.. _Boot Firmware Threats:
+
Threats to be Mitigated by the Boot Firmware
--------------------------------------------
@@ -842,6 +849,8 @@
since the |SRTM| includes all secure world components.
+.. _Runtime Firmware Threats:
+
Threats to be Mitigated by the Runtime EL3 Firmware
---------------------------------------------------