qemu: enroll certificate in MOK for dm-verity and kernel mods #3018
Conversation
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
bluca
force-pushed
the
ovmf_enroll_mok
branch
2 times, most recently
from
d97c368 to
8c11ee2
Compare
![github-advanced-security[bot]](https://avatars.githubusercontent.com/in/57789?s=60&v=4){kind=small}
bluca
force-pushed
the
ovmf_enroll_mok
branch
2 times, most recently
from
fe6e3ce to
b529b90
Compare
bluca
force-pushed
the
ovmf_enroll_mok
branch
2 times, most recently
from
b302c2c to
62800e0
Compare
behrmann
reviewed
Sep 11, 2024
bluca
force-pushed
the
ovmf_enroll_mok
branch
3 times, most recently
from
e9c7226 to
4127292
Compare
DaanDeMeyer
reviewed
Sep 12, 2024
bluca
force-pushed
the
ovmf_enroll_mok
branch
from
4127292 to
40864a9
Compare
DaanDeMeyer
requested changes
Sep 12, 2024
mkosi/qemu.py
Outdated
Comment on lines
731
to
752
| if config.secure_boot_certificate: | ||
| run( | ||
| [ | ||
| "virt-fw-vars", | ||
| "--input", vars, | ||
| "--output", ovmf_vars.name, | ||
| "--set-json", ovmf_json.name, | ||
| "--loglevel", "WARNING", | ||
| ], | ||
| sandbox=config.sandbox( | ||
| binary=qemu, | ||
| options=[ | ||
| "--bind", ovmf_vars.name, ovmf_vars.name, | ||
| "--ro-bind", ovmf_json.name, ovmf_json.name, | ||
| "--ro-bind", vars, vars, | ||
| ], | ||
| ), | ||
| ) | ||
| else: | ||
| shutil.copy2(vars, Path(ovmf_vars.name)) |
There was a problem hiding this comment.
This should be dropped, just because the image is built with a secure boot certificate shouldn't imply that we automatically add it to any given OVMF variables, especially ones provided by the user.
There was a problem hiding this comment.
it's now skipped if there are user-provided vars
DaanDeMeyer
reviewed
Sep 12, 2024
mkosi/qemu.py
Outdated
Comment on lines
652
to
695
| # In order to make the kernel use mkosi.crt to verify dm-verity volumes, we need to | ||
| # create runtime and volatile EFI variables, MokListTrustedRT and MokListRT, as | ||
| # it's only from kernel 6.11 that db is used for this purpose. Note that, unlike | ||
| # certificates in db, the certificates in MOK are only used if secure boot is enabled. | ||
| # First create an efivar with the certificate, and then read it and convert to the | ||
| # json format that virt-fw-vars expects. | ||
| # attr=4 means EFI_VARIABLE_RUNTIME_ACCESS, and the GUID is the well-known MOK one. | ||
|
|
||
| mok_sigdb = stack.enter_context(tempfile.NamedTemporaryFile(prefix="mkosi-ovmf-vars-sigdb-")) | ||
| run( | ||
| [ | ||
| "virt-fw-sigdb", | ||
| "--add-cert", "605dab50-e046-4300-abb6-3dd810dd8b23", config.secure_boot_certificate, | ||
| "--output", mok_sigdb.name, | ||
| ], | ||
| sandbox=config.sandbox( | ||
| binary=qemu, | ||
| options=[ | ||
| "--bind", mok_sigdb.name, mok_sigdb.name, | ||
| "--ro-bind", config.secure_boot_certificate, config.secure_boot_certificate, | ||
| ], | ||
| ), | ||
| ) | ||
|
|
||
| mok_json = { | ||
| "version": 2, | ||
| "variables": [ | ||
| { | ||
| "name": "MokListRT", | ||
| "guid": "605dab50-e046-4300-abb6-3dd810dd8b23", | ||
| "attr": 4, | ||
| "data": mok_sigdb.read().hex(), | ||
| }, | ||
| { | ||
| "name": "MokListTrustedRT", | ||
| "guid": "605dab50-e046-4300-abb6-3dd810dd8b23", | ||
| "attr": 4, | ||
| "data": "01", | ||
| }, | ||
| ], | ||
| } | ||
| ovmf_json.write(json.dumps(mok_json).encode()) | ||
| ovmf_json.flush() |
There was a problem hiding this comment.
Make this a function and call it from within the custom if block and assert on secure_boot_certificate
bluca
force-pushed
the
ovmf_enroll_mok
branch
from
40864a9 to
a754b55
Compare
Automatically enroll the secure boot certificate in MOK, and also set the boolean so that the kernel trusts it to verify kernel modules and dm-verity volumes. This requires secure boot to be enabled to be effective, otherwise the kernel will ignore it.
bluca
force-pushed
the
ovmf_enroll_mok
branch
from
a754b55 to
7b3d3db
Compare
DaanDeMeyer
reviewed
Sep 13, 2024
Comment on lines
+732
to
+733
| if (config.secure_boot_certificate and | ||
| (config.qemu_firmware_variables == Path("microsoft") or not config.qemu_firmware_variables)): |
There was a problem hiding this comment.
As mentioned in Telegram, I would really prefer we don't conditionalize based on whether there's a secure boot certificate configured or not as that's build time configuration and not runtime configuration. So if you'd like to have this for the microsoft keys as well please gate it behind a new constant for QemuFirmwareVariables= named microsoft+mok
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
Automatically enroll the secure boot certificate in MOK, and also set the boolean so that the kernel trusts it to verify kernel modules and dm-verity volumes. This requires secure boot to be enabled to be effective, otherwise the kernel will ignore it.