[PATCH v6 00/16] efi_loader: add secure boot support

AKASHI Takahiro takahiro.akashi at linaro.org
Wed Feb 26 05:54:32 CET 2020 

# Documentation for UEFI secure boot on U-Boot will be submitted in
# a separate patch in near future.

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


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 (16):
  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

 .travis.yml                                   |  11 +-
 cmd/efidebug.c                                |  78 +-
 cmd/nvedit.c                                  |   5 +-
 cmd/nvedit_efi.c                              |  23 +-
 configs/sandbox64_defconfig                   |   3 +
 configs/sandbox_defconfig                     |   3 +
 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             | 459 ++++++++-
 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 +++
 21 files changed, 3157 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

-- 
2.24.0

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