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Commit 699475ac authored by Joel Hutton's avatar Joel Hutton
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Document changes to auth-framework 



The data structures in the auth-framework were changed by the previous
patch, and need to be updated.

Change-Id: Icfad2ac688d03d32aa93e45f930a375abbc164a9
Signed-off-by: default avatarJoel Hutton <Joel.Hutton@Arm.com>
parent 30070427
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docs/auth-framework.rst
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......@@ -606,13 +606,13 @@ The following data structure describes an image in a CoT.
unsigned int img_id;
const struct auth_img_desc_s *parent;
img_type_t img_type;
auth_method_desc_t img_auth_methods[AUTH_METHOD_NUM];
auth_param_desc_t authenticated_data[COT_MAX_VERIFIED_PARAMS];
const auth_method_desc_t *const img_auth_methods;
const auth_param_desc_t *const authenticated_data;
} auth_img_desc_t;
A CoT is defined as an array of ``auth_image_desc_t`` structures linked together
by the ``parent`` field. Those nodes with no parent must be authenticated using
the ROTPK stored in the platform.
A CoT is defined as an array of pointers to ``auth_image_desc_t`` structures
linked together by the ``parent`` field. Those nodes with no parent must be
authenticated using the ROTPK stored in the platform.
Implementation example
----------------------
......@@ -625,15 +625,15 @@ recommended to read this guide along with the source code.
The TBBR CoT
~~~~~~~~~~~~
The CoT can be found in ``drivers/auth/tbbr/tbbr_cot.c``. This CoT consists of an
array of image descriptors and it is registered in the framework using the macro
``REGISTER_COT(cot_desc)``, where 'cot_desc' must be the name of the array
(passing a pointer or any other type of indirection will cause the registration
process to fail).
The CoT can be found in ``drivers/auth/tbbr/tbbr_cot.c``. This CoT consists of
an array of pointers to image descriptors and it is registered in the framework
using the macro ``REGISTER_COT(cot_desc)``, where 'cot_desc' must be the name
of the array (passing a pointer or any other type of indirection will cause the
registration process to fail).
The number of images participating in the boot process depends on the CoT. There
is, however, a minimum set of images that are mandatory in TF-A and thus all
CoTs must present:
The number of images participating in the boot process depends on the CoT.
There is, however, a minimum set of images that are mandatory in TF-A and thus
all CoTs must present:
- ``BL2``
- ``SCP_BL2`` (platform specific)
......@@ -674,13 +674,15 @@ Each image descriptor must specify:
is NULL, the authentication parameters will be obtained from the platform
(i.e. the BL2 and Trusted Key certificates are signed with the ROT private
key, whose public part is stored in the platform).
- ``img_auth_methods``: this array defines the authentication methods that must
be checked to consider an image authenticated. Each method consists of a
type and a list of parameter descriptors. A parameter descriptor consists of
a type and a cookie which will point to specific information required to
extract that parameter from the image (i.e. if the parameter is stored in an
x509v3 extension, the cookie will point to the extension OID). Depending on
the method type, a different number of parameters must be specified.
- ``img_auth_methods``: this points to an array which defines the
authentication methods that must be checked to consider an image
authenticated. Each method consists of a type and a list of parameter
descriptors. A parameter descriptor consists of a type and a cookie which
will point to specific information required to extract that parameter from
the image (i.e. if the parameter is stored in an x509v3 extension, the
cookie will point to the extension OID). Depending on the method type, a
different number of parameters must be specified. This pointer should not be
NULL.
Supported methods are:
- ``AUTH_METHOD_HASH``: the hash of the image must match the hash extracted
......@@ -700,11 +702,11 @@ Each image descriptor must specify:
- ``alg``: the signature algorithm used (obtained from current image)
- ``data``: the data to be signed (obtained from current image)
- ``authenticated_data``: this array indicates what authentication parameters
must be extracted from an image once it has been authenticated. Each
parameter consists of a parameter descriptor and the buffer address/size
to store the parameter. The CoT is responsible for allocating the required
memory to store the parameters.
- ``authenticated_data``: this array pointer indicates what authentication
parameters must be extracted from an image once it has been authenticated.
Each parameter consists of a parameter descriptor and the buffer
address/size to store the parameter. The CoT is responsible for allocating
the required memory to store the parameters. This pointer may be NULL.
In the ``tbbr_cot.c`` file, a set of buffers are allocated to store the parameters
extracted from the certificates. In the case of the TBBR CoT, these parameters
......@@ -722,22 +724,29 @@ Four image descriptors form the BL31 Chain of Trust:
.. code:: c
[TRUSTED_KEY_CERT_ID] = {
static const auth_img_desc_t trusted_key_cert = {
.img_id = TRUSTED_KEY_CERT_ID,
.img_type = IMG_CERT,
.parent = NULL,
.img_auth_methods = {
.img_auth_methods = (const auth_method_desc_t[AUTH_METHOD_NUM]) {
[0] = {
.type = AUTH_METHOD_SIG,
.param.sig = {
.pk = &subject_pk,
.sig = &sig,
.alg = &sig_alg,
.data = &raw_data,
.data = &raw_data
}
},
[1] = {
.type = AUTH_METHOD_NV_CTR,
.param.nv_ctr = {
.cert_nv_ctr = &trusted_nv_ctr,
.plat_nv_ctr = &trusted_nv_ctr
}
}
},
.authenticated_data = {
.authenticated_data = (const auth_param_desc_t[COT_MAX_VERIFIED_PARAMS]) {
[0] = {
.type_desc = &trusted_world_pk,
.data = {
......@@ -753,23 +762,30 @@ Four image descriptors form the BL31 Chain of Trust:
}
}
}
},
[SOC_FW_KEY_CERT_ID] = {
};
static const auth_img_desc_t soc_fw_key_cert = {
.img_id = SOC_FW_KEY_CERT_ID,
.img_type = IMG_CERT,
.parent = &cot_desc[TRUSTED_KEY_CERT_ID],
.img_auth_methods = {
.parent = &trusted_key_cert,
.img_auth_methods = (const auth_method_desc_t[AUTH_METHOD_NUM]) {
[0] = {
.type = AUTH_METHOD_SIG,
.param.sig = {
.pk = &trusted_world_pk,
.sig = &sig,
.alg = &sig_alg,
.data = &raw_data,
.data = &raw_data
}
},
[1] = {
.type = AUTH_METHOD_NV_CTR,
.param.nv_ctr = {
.cert_nv_ctr = &trusted_nv_ctr,
.plat_nv_ctr = &trusted_nv_ctr
}
}
},
.authenticated_data = {
.authenticated_data = (const auth_param_desc_t[COT_MAX_VERIFIED_PARAMS]) {
[0] = {
.type_desc = &soc_fw_content_pk,
.data = {
......@@ -778,46 +794,60 @@ Four image descriptors form the BL31 Chain of Trust:
}
}
}
},
[SOC_FW_CONTENT_CERT_ID] = {
};
static const auth_img_desc_t soc_fw_content_cert = {
.img_id = SOC_FW_CONTENT_CERT_ID,
.img_type = IMG_CERT,
.parent = &cot_desc[SOC_FW_KEY_CERT_ID],
.img_auth_methods = {
.parent = &soc_fw_key_cert,
.img_auth_methods = (const auth_method_desc_t[AUTH_METHOD_NUM]) {
[0] = {
.type = AUTH_METHOD_SIG,
.param.sig = {
.pk = &soc_fw_content_pk,
.sig = &sig,
.alg = &sig_alg,
.data = &raw_data,
.data = &raw_data
}
},
[1] = {
.type = AUTH_METHOD_NV_CTR,
.param.nv_ctr = {
.cert_nv_ctr = &trusted_nv_ctr,
.plat_nv_ctr = &trusted_nv_ctr
}
}
},
.authenticated_data = {
.authenticated_data = (const auth_param_desc_t[COT_MAX_VERIFIED_PARAMS]) {
[0] = {
.type_desc = &soc_fw_hash,
.data = {
.ptr = (void *)soc_fw_hash_buf,
.len = (unsigned int)HASH_DER_LEN
}
},
[1] = {
.type_desc = &soc_fw_config_hash,
.data = {
.ptr = (void *)soc_fw_config_hash_buf,
.len = (unsigned int)HASH_DER_LEN
}
}
}
},
[BL31_IMAGE_ID] = {
};
static const auth_img_desc_t bl31_image = {
.img_id = BL31_IMAGE_ID,
.img_type = IMG_RAW,
.parent = &cot_desc[SOC_FW_CONTENT_CERT_ID],
.img_auth_methods = {
.parent = &soc_fw_content_cert,
.img_auth_methods = (const auth_method_desc_t[AUTH_METHOD_NUM]) {
[0] = {
.type = AUTH_METHOD_HASH,
.param.hash = {
.data = &raw_data,
.hash = &soc_fw_hash,
}
.hash = &soc_fw_hash
}
}
}
};
The **Trusted Key certificate** is signed with the ROT private key and contains
the Trusted World public key and the Non-Trusted World public key as x509v3
......@@ -935,7 +965,7 @@ of SHA-256 with smaller memory footprint (~1.5 KB less) but slower (~30%).
--------------
*Copyright (c) 2017-2018, Arm Limited and Contributors. All rights reserved.*
*Copyright (c) 2017-2019, Arm Limited and Contributors. All rights reserved.*
.. _Trusted Board Boot: ./trusted-board-boot.rst
.. _Platform Porting Guide: ./porting-guide.rst
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