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The previous code required that a certificate be signed with the ROT
key before the platform's NV counter could be updated with the value
in the certificate. This implies that the Non-Trusted NV counter was
not being updated for Non-Trusted content certificates, as they cannot
be signed with the ROT key in the TBBR CoT scheme.
The code is reworked to only allow updating the platform's Trusted NV
counter when a certificate protected by the Trusted NV counter is
signed with the ROT key.
Content certificates protected by the Non-Trusted NV counter are
allowed to update the platform's Non-Trusted NV counter, assuming
that the certificate value is higher than the platform's value.
A new optional platform API has been introduced, named
plat_set_nv_ctr2(). Platforms may choose to implement it and perform
additional checks based on the authentication image descriptor before
modifying the NV counters. A default weak implementation is available
that just calls into plat_set_nv_ctr().
Fixes ARM-software/tf-issues#426
Change-Id: I4fc978fd28a3007bc0cef972ff1f69ad0413b79c
Signed-off-by: dp-arm <dimitris.papastamos@arm.com>
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A production ROM with TBB enabled must have the ability to boot test software
before a real ROTPK is deployed (e.g. manufacturing mode). Previously the
function plat_get_rotpk_info() must return a valid ROTPK for TBB to succeed.
This patch adds an additional bit `ROTPK_NOT_DEPLOYED` in the output `flags`
parameter from plat_get_rotpk_info(). If this bit is set, then the ROTPK
in certificate is used without verifying against the platform value.
Fixes ARM-software/tf-issues#381
Change-Id: Icbbffab6bff8ed76b72431ee21337f550d8fdbbb
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This patch adds support for non-volatile counter authentication to
the Authentication Module. This method consists of matching the
counter values provided in the certificates with the ones stored
in the platform. If the value from the certificate is lower than
the platform, the boot process is aborted. This mechanism protects
the system against rollback.
The TBBR CoT has been updated to include this method as part of the
authentication process. Two counters are used: one for the trusted
world images and another for the non trusted world images.
** NEW PLATFORM APIs (mandatory when TBB is enabled) **
int plat_get_nv_ctr(void *cookie, unsigned int *nv_ctr);
This API returns the non-volatile counter value stored
in the platform. The cookie in the first argument may be
used to select the counter in case the platform provides
more than one (i.e. TBSA compliant platforms must provide
trusted and non-trusted counters). This cookie is specified
in the CoT.
int plat_set_nv_ctr(void *cookie, unsigned int nv_ctr);
This API sets a new counter value. The cookie may be
used to select the counter to be updated.
An implementation of these new APIs for ARM platforms is also
provided. The values are obtained from the Trusted Non-Volatile
Counters peripheral. The cookie is used to pass the extension OID.
This OID may be interpreted by the platform to know which counter
must return. On Juno, The trusted and non-trusted counter values
have been tied to 31 and 223, respectively, and cannot be modified.
** IMPORTANT **
THIS PATCH BREAKS THE BUILD WHEN TRUSTED_BOARD_BOOT IS ENABLED. THE
NEW PLATFORM APIs INTRODUCED IN THIS PATCH MUST BE IMPLEMENTED IN
ORDER TO SUCCESSFULLY BUILD TF.
Change-Id: Ic943b76b25f2a37f490eaaab6d87b4a8b3cbc89a
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This patch adds the authentication framework that will be used as
the base to implement Trusted Board Boot in the Trusted Firmware.
The framework comprises the following modules:
- Image Parser Module (IPM)
This module is responsible for interpreting images, check
their integrity and extract authentication information from
them during Trusted Board Boot.
The module currently supports three types of images i.e.
raw binaries, X509v3 certificates and any type specific to
a platform. An image parser library must be registered for
each image type (the only exception is the raw image parser,
which is included in the main module by default).
Each parser library (if used) must export a structure in a
specific linker section which contains function pointers to:
1. Initialize the library
2. Check the integrity of the image type supported by
the library
3. Extract authentication information from the image
- Cryptographic Module (CM)
This module is responsible for verifying digital signatures
and hashes. It relies on an external cryptographic library
to perform the cryptographic operations.
To register a cryptographic library, the library must use the
REGISTER_CRYPTO_LIB macro, passing function pointers to:
1. Initialize the library
2. Verify a digital signature
3. Verify a hash
Failing to register a cryptographic library will generate
a build time error.
- Authentication Module (AM)
This module provides methods to authenticate an image, like
hash comparison or digital signatures. It uses the image parser
module to extract authentication parameters, the crypto module
to perform cryptographic operations and the Chain of Trust to
authenticate the images.
The Chain of Trust (CoT) is a data structure that defines the
dependencies between images and the authentication methods
that must be followed to authenticate an image.
The Chain of Trust, when added, must provide a header file named
cot_def.h with the following definitions:
- COT_MAX_VERIFIED_PARAMS
Integer value indicating the maximum number of authentication
parameters an image can present. This value will be used by the
authentication module to allocate the memory required to load
the parameters in the image descriptor.
Change-Id: Ied11bd5cd410e1df8767a1df23bb720ce7e58178
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