On secure boot enabled systems, a verified kernel may need to kexec additional kernels. For example, it may be used as a bootloader needing to kexec a target kernel or it may need to kexec a crashdump kernel. In such cases, it may want to verify the signature of the next kernel image.
It is possible that the new kernel image is signed with third party keys which are stored as platform or firmware keys in the 'db' variable. The kernel, however, can not directly verify these platform keys, and an administrator may therefore not want to trust them for arbitrary usage. In order to differentiate platform keys from other keys and provide the necessary separation of trust the kernel needs an additional keyring to store platform/firmware keys. The secure boot key database is expected to store the keys as EFI Signature List(ESL). The patch set uses David Howells and Josh Boyer's patch to access and parse the ESL to extract the certificates and load them onto the platform keyring. The last patch in this patch set adds support for IMA-appraisal to verify the kexec'ed kernel image based on keys stored in the platform keyring. Changelog: v0: - The original patches loaded the certificates onto the secondary trusted keyring. This patch set defines a new keyring named ".platform" and adds the certificates to this new keyring - removed CONFIG EFI_SIGNATURE_LIST_PARSER and LOAD_UEFI_KEYS - moved files from certs/ to security/integrity/platform_certs/ Dave Howells (2): efi: Add EFI signature data types efi: Add an EFI signature blob parser Josh Boyer (2): efi: Import certificates from UEFI Secure Boot efi: Allow the "db" UEFI variable to be suppressed Nayna Jain (3): integrity: define a trusted platform keyring integrity: load certs to the platform keyring ima: support platform keyring for kernel appraisal include/linux/efi.h | 34 ++++ security/integrity/Kconfig | 11 ++ security/integrity/Makefile | 5 + security/integrity/digsig.c | 115 ++++++++---- security/integrity/ima/ima_appraise.c | 11 +- security/integrity/integrity.h | 23 ++- security/integrity/platform_certs/efi_parser.c | 112 ++++++++++++ security/integrity/platform_certs/load_uefi.c | 192 +++++++++++++++++++++ .../integrity/platform_certs/platform_keyring.c | 62 +++++++ 9 files changed, 527 insertions(+), 38 deletions(-) create mode 100644 security/integrity/platform_certs/efi_parser.c create mode 100644 security/integrity/platform_certs/load_uefi.c create mode 100644 security/integrity/platform_certs/platform_keyring.c -- 2.13.6
