[v7,0/2] Add support for ECDSA-signed kernel modules

Message

Stefan Berger June 28, 2021, 9:43 p.m. UTC

From: Stefan Berger <[e-mail]>

This series adds support for ECDSA-signed kernel modules. It also
attempts to address a kbuild issue where a developer created an ECDSA
key for signing kernel modules and then builds an older version of the
kernel, when bisecting the kernel for example, that does not support
ECDSA keys.

The first patch addresses the kbuild issue of needing to delete that
ECDSA key if it is in certs/signing_key.pem and trigger the creation
of an RSA key. However, for this to work this patch would have to be
backported to previous versions of the kernel but would also only work
for the developer if he/she used a stable version of the kernel to which
this patch was applied. So whether this patch actually achieves the
wanted effect is not always guaranteed.

The 2nd patch adds the support for the ECSDA-signed kernel modules.

  Stefan

v7:
  - Changed Kconfig reference to kernel version from 5.11 to 5.13
  - Redirecting stderr of openssl to NULL device to address kernel robot
    detected issue
  - Replaced $(CONFIG_MODULE_SIG_KEY) with "certs/signing_key.pem" following
    Linus's suggestion

v6:
  - Patch 2/4 is fixing V4's 1/2 and 4/4 is fixing V4's 2/2. Both fixup
    patches to be squashed.

v5:
  - do not touch the key files if openssl is not installed; likely
    addresses an issue pointed out by kernel test robot

v4:
  - extending 'depends on' with MODULES to (IMA_APPRAISE_MODSIG && MODULES)
  
v3:
  - added missing OIDs for ECDSA signed hashes to pkcs7_sig_note_pkey_algo
  - added recommendation to use string hash to Kconfig help text

v2:
  - Adjustment to ECDSA key detector string in 2/2
  - Rephrased cover letter and patch descriptions with Mimi


Stefan Berger (2):
  certs: Trigger creation of RSA module signing key if it's not an RSA
    key
  certs: Add support for using elliptic curve keys for signing modules

 certs/Kconfig                         | 26 ++++++++++++++++++++++++++
 certs/Makefile                        | 21 +++++++++++++++++++++
 crypto/asymmetric_keys/pkcs7_parser.c |  8 ++++++++
 3 files changed, 55 insertions(+)