On Wed, Jan 26, 2022 at 03:43:07PM +0200, Jarkko Sakkinen wrote: > On Tue, Jan 25, 2022 at 09:58:26PM -0500, Eric Snowberg wrote: > > Back in 2013 Linus requested a feature to allow end-users to have the > > ability "to add their own keys and sign modules they trust". This was > > his *second* order outlined here [1]. There have been many attempts > > over the years to solve this problem, all have been rejected. Many > > of the failed attempts loaded all preboot firmware keys into the kernel, > > including the Secure Boot keys. Many distributions carry one of these > > rejected attempts [2], [3], [4]. This series tries to solve this problem > > with a solution that takes into account all the problems brought up in > > the previous attempts. > > > > On UEFI based systems, this series introduces a new Linux kernel keyring > > containing the Machine Owner Keys (MOK) called machine. It also defines > > a new MOK variable in shim. This variable allows the end-user to decide > > if they want to load MOK keys into the machine keyring. > > > > By default, nothing changes; MOK keys are not loaded into the machine > > keyring. They are only loaded after the end-user makes the decision > > themselves. The end-user would set this through mokutil using a new > > --trust-mok option [5]. This would work similar to how the kernel uses > > MOK variables to enable/disable signature validation as well as use/ignore > > the db. Any kernel operation that uses either the builtin or secondary > > trusted keys as a trust source shall also reference the new machine > > keyring as a trust source. > > > > Secure Boot keys will never be loaded into the machine keyring. They > > will always be loaded into the platform keyring. If an end-user wanted > > to load one, they would need to enroll it into the MOK. > > > > Unlike previous versions of this patch set, IMA support has been removed > > to simplify the series. After acceptance, a follow-on series will add IMA > > support. > > > > Steps required by the end user: > > > > Sign kernel module with user created key: > > $ /usr/src/kernels/$(uname -r)/scripts/sign-file sha512 \ > > machine_signing_key.priv machine_signing_key.x509 my_module.ko > > > > Import the key into the MOK > > $ mokutil --import machine_signing_key.x509 > > > > Setup the kernel to load MOK keys into the .machine keyring > > $ mokutil --trust-mok > > > > Then reboot, the MokManager will load and ask if you want to trust the > > MOK key and enroll the MOK into the MOKList. Afterwards the signed kernel > > module will load. > > > > I have included a link to the mokutil [5] changes I have made to support > > this new functionality. The shim changes have now been accepted > > upstream [6]. > > > > Upstream shim is located here [7], the build instructions are here [8]. > > TLDR: > > > > $ git clone --recurse-submodules https://github.com/rhboot/shim > > $ cd shim > > $ make > > > > After building shim, move shimx64.efi and mmx64.efi to the vendor or > > distribution specific directory on your EFI System Partition (assuming > > you are building on x86). The instructions above are the minimal > > steps needed to build shim to test this feature. It is assumed > > Secure Boot shall not be enabled for this testing. To do testing > > with Secure Boot enabled, all steps in the build instructions [8] > > must be followed. > > > > Instructions for building mokutil (including the new changes): > > > > $ git clone -b mokvars-v3 https://github.com/esnowberg/mokutil.git > > $ cd mokutil/ > > $ ./autogen.sh > > $ make > > > > [1] https://marc.info/?l=linux-kernel&m=136185386310140&w=2 > > [2] https://lore.kernel.org/lkml/1479737095.2487.34.camel@xxxxxxxxxxxxxxxxxx/ > > [3] https://lore.kernel.org/lkml/1556221605.24945.3.camel@xxxxxxxxxxxxxxxxxxxxx/ > > [4] https://lore.kernel.org/linux-integrity/1e41f22b1f11784f1e943f32bf62034d4e054cdb.camel@xxxxxxxxxxxxxxxxxxxxx/ > > [5] https://github.com/esnowberg/mokutil/tree/mokvars-v3 > > [6] https://github.com/rhboot/shim/commit/4e513405b4f1641710115780d19dcec130c5208f > > [7] https://github.com/rhboot/shim > > [8] https://github.com/rhboot/shim/blob/main/BUILDING > > > > Eric Snowberg (8): > > integrity: Fix warning about missing prototypes > > integrity: Introduce a Linux keyring called machine > > integrity: add new keyring handler for mok keys > > KEYS: store reference to machine keyring > > KEYS: Introduce link restriction for machine keys > > efi/mokvar: move up init order > > integrity: Trust MOK keys if MokListTrustedRT found > > integrity: Only use machine keyring when uefi_check_trust_mok_keys is > > true > > > > certs/system_keyring.c | 44 ++++++++++- > > drivers/firmware/efi/mokvar-table.c | 2 +- > > include/keys/system_keyring.h | 14 ++++ > > security/integrity/Kconfig | 13 ++++ > > security/integrity/Makefile | 1 + > > security/integrity/digsig.c | 15 +++- > > security/integrity/integrity.h | 17 +++- > > .../platform_certs/keyring_handler.c | 18 ++++- > > .../platform_certs/keyring_handler.h | 5 ++ > > security/integrity/platform_certs/load_uefi.c | 4 +- > > .../platform_certs/machine_keyring.c | 77 +++++++++++++++++++ > > 11 files changed, 202 insertions(+), 8 deletions(-) > > create mode 100644 security/integrity/platform_certs/machine_keyring.c > > > > > > base-commit: e783362eb54cd99b2cac8b3a9aeac942e6f6ac07 > > -- > > 2.18.4 > > > > Thank you. I'll pick these soon. Is there any objections? Mimi brought up that we need a MAINTAINERS update for this and also .platform. We have these: - KEYS/KEYRINGS - CERTIFICATE HANDLING I would put them under KEYRINGS for now and would not consider further subdivision for the moment. /Jarkko
