This will be used by Tpm2Handle instances, which is added in later patches.
The refcounting allows the context to be retained until all Tpm2Handles have
been cleaned up, and the initial ref is released, before cleaning the context.
The 'pcr_bank' functions operate on hash algs, and are not specific to the PCR
banks, while the 'primary_alg' functions operate on asymmetric algs, and are
not specific to primary keys.
EFI_LOADER_VARIABLE() already applies to the stringify to construct the
path of EFI variable in efivars, so it is wrong to enclose the name of
EFI variable with the quotes. Otherwise, the following errors are
reported.
Reading EFI variable /sys/firmware/efi/efivars/StubFeatures-4a67b082-0a4c-41cf-b6c7-440b29bb8c4f.
Reading EFI variable /sys/firmware/efi/efivars/"StubPcrKernelImage"-4a67b082-0a4c-41cf-b6c7-440b29bb8c4f.
open("/sys/firmware/efi/efivars/"StubPcrKernelImage"-4a67b082-0a4c-41cf-b6c7-440b29bb8c4f") failed: No such file or directory
Reading EFI variable /sys/firmware/efi/efivars/"StubPcrKernelParameters"-4a67b082-0a4c-41cf-b6c7-440b29bb8c4f.
open("/sys/firmware/efi/efivars/"StubPcrKernelParameters"-4a67b082-0a4c-41cf-b6c7-440b29bb8c4f") failed: No such file or directory
Reading EFI variable /sys/firmware/efi/efivars/"StubPcrInitRDSysExts"-4a67b082-0a4c-41cf-b6c7-440b29bb8c4f.
open("/sys/firmware/efi/efivars/"StubPcrInitRDSysExts"-4a67b082-0a4c-41cf-b6c7-440b29bb8c4f") failed: No such file or directory
Signed-off-by: Jia Zhang <zhang.jia@linux.alibaba.com>
-1 was used everywhere, but -EBADF or -EBADFD started being used in various
places. Let's make things consistent in the new style.
Note that there are two candidates:
EBADF 9 Bad file descriptor
EBADFD 77 File descriptor in bad state
Since we're initializating the fd, we're just assigning a value that means
"no fd yet", so it's just a bad file descriptor, and the first errno fits
better. If instead we had a valid file descriptor that became invalid because
of some operation or state change, the other errno would fit better.
In some places, initialization is dropped if unnecessary.
Often it's useful to add multiple signatures in the signature JSON file
to embedd in a single .pcrsig. (For example, a signature by key X for
boot phase "enter-initrd" and one by key Y for
"enter-initrd:leave-initrd" or so). Make this easy, by adding the
ability to append signatures to a previously generated JSON file.
This adds two more phases to the PCR boot phase logic: "sysinit" +
"final".
The "sysinit" one is placed between sysinit.target and basic.target.
It's good to have a milestone in this place, since this is after all
file systems/LUKS volumes are in place (which sooner or later should
result in measurements of their own) and before services are started
(where we should be able to rely on them to be complete).
This is particularly useful to make certain secrets available for
mounting secondary file systems, but making them unavailable later.
This breaks API in a way (as measurements during runtime will change),
but given that the pcrphase stuff wasn't realeased yet should be OK.
Let's separate the PE section options in the --help text to make clearer
that they are about PE sections, and thus make things less confusing
regarding the cryptic names. Specifically, there's now a separate
section in the --help text that looks like this:
<snip>
UKI PE Section Options: UKI PE Section
--linux=PATH Path Linux kernel image → .linux
--osrel=PATH Path to os-release file → .osrel
--cmdline=PATH Path to file with kernel command line → .cmdline
--initrd=PATH Path to initrd image → .initrd
--splash=PATH Path to splash bitmap → .splash
--dtb=PATH Path to Devicetree file → .dtb
--pcrpkey=PATH Path to public key for PCR signatures → .pcrpkey
</snipe>
(The section title is underlined, like we usually do it)
I think separating this out, and organizing the section name in tabular
form emphasizes nicely where this switches get their name from and what
they mean.
Hopefully addresses concerns from
https://github.com/systemd/systemd/pull/24458#discussion_r967052720 in a
diferent way.
(Also dropped a hint regarding DER format for public key. it's simply
wrong, we use PEM like everyone else on Linux. Outside of Java land DER
isn't popular, so we don't need to mention it here in the --help text,
man page should be enough.)
This way we can use it directly in measure.c, and thus remove a bit of
redundant code.
OpenSSL prefers uppercasing the MD names, others don't hence let's be
lenient here.
Let's say what we actually measure, not what into (which is obvious
anyway).
This is generally more descriptive, but also good for later work that
allows measuring the boot phase too.
These aren't wired up yet to do anything useful. For now we just define
them.
This sections are supposed to carry a signature for expected
measurements on PCR 11 if this kernel is booted, in the JSON format
"systemd-measure sign" generates, and the public key used for the
signature.
The idea is to embedd the signature and the public key in unified
kernels and making them available to userspace, so that userspace can
easily access them and enroll (for which the public key is needed) or
unlock (for which the PCR signature is needed) LUKS2 volumes and
credentials that are bound to the currently used kernel version stream.
Why put these files in PE sections rather than just into simple files in
the initrd or into the host fs?
The signature cannot be in the initrd, since it is after all covering
the initrd, and thus the initrd as input for the calculation cannot
carry the result of the calculation. Putting the signature onto the root
fs sucks too, since we typically want to unlock the root fs with it,
hence it would be inaccessible for it's primary purpose then.
The public key could be in the initrd or in the root fs, there's no
technical restriction for that. However, I still think it's a good idea
to put it in a PE section as well, because this means the piece of code
that attaches the signature can also attach the public key easily in one
step, which is nice since it allows separating the roles of the
kernel/initrd/root fs builder, and the role of the signer, and the
former doesn't have to have knowledge about what the latter is going to
add to the image.
Note that the signature section is excluded from the TPM measurements
sd-stub does about its resource sections, since – as mentioned – it's
the expected output of the signing operation whose input are the
measurements, hence it cannot also be input to them. The public key
section is included in the measurements however.
When using --current switch, copy in current hash, don't just reassign
buffers forgetting about the old.
While we are at it, allocate the local copy buffer later, in
measure_pcr() as we won#t need it in the --current case.
This allows allows shortcutting measurements of the specified files and
use the information from /sys/ instead.
This is not too useful on its own given that "systemd-measure status"
already exists which displays the current, relevant PCR values. The main
difference is how "complete" the information is. "status" will detect if
the measurements make any sense, and show more than PCR 11. "calculate
--current" otoh only reads PCR 11 and uses that, and that's really it.
This is mainly preparation for later work to add PCR signing to the
tool, where usually it makes most sense to sign prepared kernel images,
but for testing it's really useful to shortcut signing to the current
PCR values instead
For now, this simply outputs the PCR hash values expected for a kernel
image, if it's measured like sd-stub would do it.
(Later on, we can extend the tool, to optionally sign these
pre-calculated measurements, in order to implement signed PCR policies
for disk encryption.)
Dan Streetman
Zbigniew Jędrzejewski-Szmek
Jia Zhang
Lennart Poettering
Li kunyu
Frantisek Sumsal