[U-Boot] [PATCH v2 0/6] rsa: extend rsa_verify() for UEFI secure boot

AKASHI Takahiro takahiro.akashi at linaro.org
Tue Oct 29 06:46:30 UTC 2019

# Please note that this patch set is based on v2 of my "importing
# x509/pkcs7 parsers from linux" patch[2] and will have to be updated
# due to remval of test/lib/Kconfig once v3 or later is submitted.
# The needed change is trivial, though.

The current rsa_verify() requires five parameters for a RSA public key
for efficiency while RSA, in theory, requires only two. In addition,
those parameters are expected to come from FIT image.

So this function won't fit very well when we want to use it for the purpose
of implementing UEFI secure boot, in particular, image authentication
as well as variable authentication, where the essential two parameters
are set to be retrieved from one of X509 certificates in signature

So, in this patch, additional three parameters will be calculated
on the fly when rsa_verify() is called without fdt which should contain
parameters above.

This calculation heavily relies on "big-number (or multi-precision)
library." Therefore some routines from BearSSL[1] under MIT license are
imported in this implementation. See Patch#4.
# Please let me know if this is not appropriate.

# Checkpatch will complain with lots of warnings/errors, but
# I intentionally don't fix them for maximum maintainability.

  [1] https://bearssl.org/
  [2] https://lists.denx.de/pipermail/u-boot/2019-October/388263.html

Changes in v2 (Oct 29, 2019)
* fix build errors at Travis CI
* not include linux/kconfig.h (patch#1)
* add a separate patch for adding CONFIG_RSA_VERIFY_WITH_PKEY (patch#2)
* take a prerequisite patch from my "secure boot patch" (patch#3)
* add a dependency on RSA_PUBLIC_KEY_PARSER (patch#4)
* remove "inline" directives (patch#4)
* add function descriptions, which mostly come from BearSSL's src/inner.h
* improve Kconfig help text after Simon's comment (patch#5)
* add function description of rsa_verify_with_pkey() (patch#5)
* modify rsa_verify() to use "if (CONFIG_IS_ENABLED(...) " style
  rather than "#ifdef CONFIG_..." (patch#5)
* add function tests (patch#6)

Changes in v1 (Oct 9, 2019)
* fix a build error on pine64-lts_defconfig (reported by Heinrich)
  by defining FIT_IMAGE_ENABLE_VERIFY flag and adding
  SPL_RSA_VERIFY config (patch#1)
* remove FIT-specific code from image-sig.c and put them to new
  image-fit-sig.c to allow us to disable CONFIG_FIT_SIGNATURE (patch#1)
* compile rsa-keyprop.c only if necessary (i.e. if
* add SPDX license identifier in rsa-keyprop.c (patch#2)
* include <common.h> instead of <stdio.h> (patch#2)
* use U-Boot's byteorder helper functions instead of BearSSL's (patch#2)

AKASHI Takahiro (6):
  lib: rsa: decouple rsa from FIT image verification
  include: image.h: add key info to image_sign_info
  lib: rsa: generate additional parameters for public key
  lib: rsa: add rsa_verify_with_pkey()
  test: add rsa_verify() unit test

 Kconfig                      |   1 +
 common/Makefile              |   3 +-
 common/image-fit-sig.c       | 417 ++++++++++++++++++++
 common/image-fit.c           |   6 +-
 common/image-sig.c           | 396 -------------------
 include/image.h              |  23 +-
 include/u-boot/rsa-mod-exp.h |  21 +
 lib/rsa/Kconfig              |  27 ++
 lib/rsa/Makefile             |   3 +-
 lib/rsa/rsa-keyprop.c        | 717 +++++++++++++++++++++++++++++++++++
 lib/rsa/rsa-verify.c         | 131 +++++--
 test/lib/Kconfig             |  12 +
 test/lib/Makefile            |   1 +
 test/lib/rsa.c               | 207 ++++++++++
 tools/Makefile               |   2 +-
 15 files changed, 1531 insertions(+), 436 deletions(-)
 create mode 100644 common/image-fit-sig.c
 create mode 100644 lib/rsa/rsa-keyprop.c
 create mode 100644 test/lib/rsa.c


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