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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

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