This function will check if a given handle to device is an EFI system
partition. It will be utilised in implementing capsule-on-disk feature.

Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
Add function description. Return bool.
Reviewed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>

The guard doesn't make any difference, so remove it.

Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
Suggested-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Reviewed-by: Heinrich Schuchardt <xypron.glpk@gmx.de>

In subsequent patches UEFI variables shalled be stored on the EFI system
partition. Hence we need to identify the EFI system partition.

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>

With this commit, image validation can be enforced, as UEFI specification
section 32.5 describes, if CONFIG_EFI_SECURE_BOOT is enabled.

Currently we support
* authentication based on db and dbx,
  so dbx-validated image will always be rejected.
* following signature types:
    EFI_CERT_SHA256_GUID (SHA256 digest for unsigned images)
    EFI_CERT_X509_GUID (x509 certificate for signed images)
Timestamp-based certificate revocation is not supported here.

Internally, authentication data is stored in one of certificates tables
of PE image (See efi_image_parse()) and will be verified by
efi_image_authenticate() before loading a given image.

It seems that UEFI specification defines the verification process
in a bit ambiguous way. I tried to implement it as closely to as
EDK2 does.

Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>

With this commit, EFI_VARIABLE_TIME_BASED_AUTHENTICATED_WRITE_ACCESS
is supported for authenticated variables and the system secure state
will transfer between setup mode and user mode as UEFI specification
section 32.3 describes.

Internally, authentication data is stored as part of authenticated
variable's value. It is nothing but a pkcs7 message (but we need some
wrapper, see efi_variable_parse_signature()) and will be validated by
efi_variable_authenticate(), hence efi_signature_verify_with_db().

Associated time value will be encoded in "{...,time=...}" along with
other UEFI variable's attributes.

Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>

efi_signature_parse_sigdb() is a helper function will be used to parse
signature database variable and instantiate a signature store structure
in later patches.

Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>

In this commit, implemented are a couple of helper functions which will be
used to materialize variable authentication as well as image authentication
in later patches.

Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>

'vendor' is both an input and an output parameter. So it cannot be
constant.

Fixes: 0bda81bfdc5c ("efi_loader: use const efi_guid_t * for variable services")
Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>

This is a preparatory patch.
Those functions will be used in an implementation of UEFI firmware
management protocol as part of my capsule update patch.

Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>

Following kernel's proposal for an arch-agnostic initrd loading
mechanism [1] let's implement the U-boot counterpart.
This new approach has a number of advantages compared to what we did up
to now. The file is loaded into memory only when requested limiting the
area of TOCTOU attacks. Users will be allowed to place the initramfs
file on any u-boot accessible partition instead of just the ESP one.
Finally this is an attempt of a generic interface across architectures
in the linux kernel so it makes sense to support that.

The file location is intentionally only supported as a config option
argument(CONFIG_EFI_INITRD_FILESPEC), in an effort to enhance security.
Although U-boot is not responsible for verifying the integrity of the
initramfs, we can enhance the offered security by only accepting a
built-in option, which will be naturally verified by UEFI Secure Boot.
This can easily change in the future if needed and configure that via ENV
or UEFI variable.

[1] https://lore.kernel.org/linux-efi/20200207202637.GA3464906@rani.riverdale.lan/T/#m4a25eb33112fab7a22faa0fd65d4d663209af32f

Signed-off-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>