[PATCH v7 00/17] efi_loader: add secure boot support
AKASHI Takahiro
takahiro.akashi at linaro.org
Fri Apr 17 09:21:11 CEST 2020
Heinrich,
I was notified of some wrong implementation in this patch set.
I think that the change will be contained in efi_signature_verify()
function, but it is so essential in terms of "verification" logic.
While I'm still investigating the issue to determine what impact
it will have, I would have to, in the worst case, ask you to revert
all the commits.
Some details:
In my current implementation, a signature in UEFI image will be
verified with one of certificates in UEFI signature database
(PK/KEK/db).
The true logic would be that a signature be verified with a corresponding
certificate also in the image (known as signers), and then that certificate
be verified with UEFI signature database.
It is particularly crucial if we want to support "intermediate"
certificates (or chain-of-trust) in UEFI image.
I will keep you updated when I have some progress.
Thanks,
-Takahiro Akashi
On Tue, Apr 14, 2020 at 11:51:37AM +0900, AKASHI Takahiro wrote:
> One of major missing features in current UEFI implementation is "secure boot."
> The ultimate goal of my attempt is to implement image authentication based
> on signature and provide UEFI secure boot support which would be fully
> compliant with UEFI specification, section 32[1].
> (The code was originally developed by Patrick Wildt.)
>
> This patch set requires one prerequisite[2]. For complete workable cod,
> see my repository[3].
>
> My "non-volatile" support[4], which is under discussion, is not mandatory
> and so not included here, but this inevitably implies that, for example,
> signature database variables, like db and dbx, won't be persistent unless
> you explicitly run "env save" command.
> Anyhow, Linaro is also working on implementing real "secure storage"
> solution based on TF-A and OP-TEE.
>
>
> Supported features:
> * image authentication based on db and dbx
> * supported signature types are
> EFI_CERT_SHA256_GUID (SHA256 digest for unsigned images)
> EFI_CERT_X509_GUID (x509 certificate for signed images)
> * SecureBoot/SignatureSupport variables
> * SetupMode and user mode
> * variable authentication based on PK and KEK
> EFI_VARIABLE_TIME_BASED_AUTHENTICATED_WRITE_ACCESS
> * basic pytest test cases
>
> Unsupported features: (marked as TODO in most cases in the source code,
> and won't be included in this series)
> * hash algorithms other than SHA256
> * dbt: timestamp(RFC6131)-based certificate revocation
> * dbr: OS recovery
> * xxxDefault: default values for signature stores
> * transition to AuditMode and DeployedMode
> * recording rejected images in EFI_IMAGE_EXECUTION_INFO_TABLE
> * verification "policy", in particular, check against signature's owner
> * private authenticated variables
> * variable authentication with EFI_VARIABLE_ENHANCED_AUTHENTICATED_ACCESS
> * real secure storage support, including hardware-specific PK (Platform Key)
> installation
>
> TODO's other than "Unsupported features": (won't be included in this series)
> * fail recovery, in particular, in modifying authenticated variables
> * support read-only attributes of well-defined global variables
> in particular, "SignatureSupport"
> * Extensive test suite (or more test cases) to confirm compatibility
> with EDK2
> => I requested EDK SCT community to add tests[5].
>
> Test:
> * My pytest, included in this patch set, passed.
> * efi_selftest passed. (At least no regression.)
> * Travis CI tests have passed.
>
> Known issues:
> * efitools is used in pytest, and its version must be v1.5.2 or later.
> (Solution: You can define EFITOOLS_PATH in defs.py for your own efitools.)
>
>
> Hints about how to use:
> (Please see other documents, or my pytest scripts, for details.)
> * You can create your own certificates with openssl.
> * You can sign your application with sbsign (on Ubuntu).
> * You can create raw data for signature database with efitools, and
> install/manage authenticated variables with "env -set -e" command
> or efitools' "UpdateVars.efi" application.
>
>
> [1] https://uefi.org/sites/default/files/resources/UEFI_Spec_2_8_final.pdf
> [2] https://lists.denx.de/pipermail/u-boot/2020-January/398057.html
> (extend rsa_verify() for UEFI secure boot)
> [3] http://git.linaro.org/people/takahiro.akashi/u-boot.git/ efi/secboot
> [4] https://lists.denx.de/pipermail/u-boot/2019-September/382835.html
> (non-volatile variables support)
> [5] https://bugzilla.tianocore.org/show_bug.cgi?id=2230
> [6] https://lists.denx.de/pipermail/u-boot/2020-February/399446.html
>
>
> Changes in v7 (Apr 14, 2020)
> * fix a usage of qsort() in efi_image_parse() (patch#7)
> * merge my document patch[6] (patch#17)
>
> Changes in v6 (Feb 26, 2020)
> * fix 'make htmldocs' warnings (patch#4,#7)
> * refactor efi_load_pe() to avoid test_efi_fit.py error (patch#7)
> * fix pytest warnings (patch#14)
>
> Changes in v5 (Jan 28, 2020)
> * rebased to pre-v2020.04-rc1 (fixed some merge conflicts)
> * remove already-merged commits (v4's patch#1)
> * fix a compile error caused by gcc 9.x (patch#4)
> * return SECURITY_VIOLATION instead of ACCESS_DENIED if authentication fails
> (patch#7)
> * use qsort() for section sorting (patch#7)
> * add "efidebug test" sub-command (patch#11)
> * add efi_start_image(SECURITY_VIOLATION) test (patch#14)
>
> Changes in v4 (Dec 18, 2019)
> * adjust EFI_SECURE_BOOT dependencies due to a change of RSA extension patch v5
> (patch#2)
> * change "imply" to "select" against kconfig dependencies (patch#2)
> * otherwise, no functional changes
>
> Changes in v3 (Dec 9, 2019)
> * allow for arbitrary number of regions in efi_image_region_add()
> (patch#3, #5 and #8)
> * remove a redundant check in a while loop at efi_sigstore_free() (patch#4)
>
> Changes in v2 (Nov 26, 2019)
> * rebased to v2020.01-rc3
> * rename IMAGE_DIRECTORY_ENTRY_CERTTABLE to IMAGE_DIRECTORY_ENTRY_SECURITY
> (patch#1,#9)
> * add comments (patch#1)
> * drop v1's patch#2 as it is no longer necessary
> * drop v1's patch#3 as other "SECURE_BOOT" architectures have renamed
> this option and no longer use it
> * add structure descriptions (patch#3)
> * rework hash calculation code in efi_signature_verify() and remove
> an odd constant, WinIndrectSha256 (patch#3)
> * move travis.yml changes to a separate patch (patch#12, #16)
> * yield_fixture() -> fixture() (patch#12)
> * call console.restart_uboot() at every test case (13,#14)
> * add patch#15; enable UEFI-related configurations by default on sandbox
> * add patch#16; modify Travis CI environment to run UEFI secure boot test
>
> Changes in v1 (Nov 13, 2019)
> * rebased to v2020.01-rc
> * remove already-merged patches
> * re-work the patch set for easier reviews, including
> - move a config definition patch forward (patch#4)
> - refactor/rename verification functions (patch#5/#10)
> - split signature database parser as a separate patch (patch#6)
> - split secure state transition code as a separate patch (patch#8)
> - move most part of init_secure_boot() into init_variables() (patch#8)
> - split test environment setup from test patches (patch#14)
> * add function descriptions (patch#5-#11)
> * make sure the section list is sorted in ascending order in hash
> calculation of PE image (patch#10)
> * add a new "-at" (authenticated access) option to "env -e" (patch#13)
> * list required host packages, in particular udisks2, in pytest
> (patch#14)
> * modify conftest.py to run under python3 (patch#14)
> * use a partition on a disk instead of a whole disk without partition
> table (patch#14)
> * reduce dependency on efitools, yet relying on its host tools (patch#14)
> * modify pytests to catch up wth latest changes of "env -e" syntax
> (patch#15,#16)
>
> RFC (Sept 18, 2019)
>
> AKASHI Takahiro (17):
> efi_loader: add CONFIG_EFI_SECURE_BOOT config option
> efi_loader: add signature verification functions
> efi_loader: add signature database parser
> efi_loader: variable: support variable authentication
> efi_loader: variable: add secure boot state transition
> efi_loader: variable: add VendorKeys variable
> efi_loader: image_loader: support image authentication
> efi_loader: set up secure boot
> cmd: env: use appropriate guid for authenticated UEFI variable
> cmd: env: add "-at" option to "env set -e" command
> cmd: efidebug: add "test bootmgr" sub-command
> efi_loader, pytest: set up secure boot environment
> efi_loader, pytest: add UEFI secure boot tests (authenticated
> variables)
> efi_loader, pytest: add UEFI secure boot tests (image)
> sandbox: add extra configurations for UEFI and related tests
> travis: add packages for UEFI secure boot test
> efi_loader: add some description about UEFI secure boot
>
> .travis.yml | 11 +-
> cmd/efidebug.c | 78 +-
> cmd/nvedit.c | 5 +-
> cmd/nvedit_efi.c | 23 +-
> configs/sandbox64_defconfig | 3 +
> configs/sandbox_defconfig | 3 +
> doc/uefi/uefi.rst | 77 ++
> include/efi_api.h | 87 ++
> include/efi_loader.h | 91 +-
> lib/efi_loader/Kconfig | 18 +
> lib/efi_loader/Makefile | 1 +
> lib/efi_loader/efi_boottime.c | 10 +-
> lib/efi_loader/efi_image_loader.c | 462 ++++++++-
> lib/efi_loader/efi_setup.c | 38 +
> lib/efi_loader/efi_signature.c | 809 +++++++++++++++
> lib/efi_loader/efi_variable.c | 952 ++++++++++++++++--
> test/py/README.md | 8 +
> test/py/tests/test_efi_secboot/conftest.py | 151 +++
> test/py/tests/test_efi_secboot/defs.py | 21 +
> .../py/tests/test_efi_secboot/test_authvar.py | 282 ++++++
> test/py/tests/test_efi_secboot/test_signed.py | 117 +++
> .../tests/test_efi_secboot/test_unsigned.py | 121 +++
> 22 files changed, 3237 insertions(+), 131 deletions(-)
> create mode 100644 lib/efi_loader/efi_signature.c
> create mode 100644 test/py/tests/test_efi_secboot/conftest.py
> create mode 100644 test/py/tests/test_efi_secboot/defs.py
> create mode 100644 test/py/tests/test_efi_secboot/test_authvar.py
> create mode 100644 test/py/tests/test_efi_secboot/test_signed.py
> create mode 100644 test/py/tests/test_efi_secboot/test_unsigned.py
>
> --
> 2.25.2
>
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