We inquire the EFI var for this at two places, let's add a helper that
queries it and gracefully handles it if we can't get it, by returning a
zero mask, i.e. no features supported.
Let's make some stuff const. Most importanly call AllocatePages() with
a pointer to an EFI_PHYSICAL_ADDRESS instead of a pointer to a
pointer. On 64bit this makes no difference, but on i386 this is simply
not correct, since EFI_PHYSICAL_ADDRESS is 64bit there, even though
pointers are 32bit.
let's move showing of the splash screen to the earliest place we know
the splash bmp address. After all a splash screen is all about showing
as early as we can. This matters as doing TPM stuff or packing up a
large cpio might take time.
While we are at it, move the conditionalization of the splash screen
into the function instead of doing it ahead of calling it. This should
encapsulate things more nicely.
This adds support for the EFI stub to look for credential files and
sysext files next to the EFI kernel image being loaded, and pack them up
in an initrd cpio image, and pass them to the kernel.
Specifically, for a kernel image foo.efi it looks for
foo.efi.extra.d/*.cred and packs these files up in an initrd, placing it
inside a directory /.extra/credentials/. It then looks for
foo.efi.extra.d/*.raw and pack these files up in an initrd, placing them
inside a directory /.extra/sysexts/. It then concatenates any other
initrd with these two initrds, so they are combined.
Or in other words auxiliary files placed next to the kernel image are
picked up automatically by the EFI stub and be made available in the
initrd in the /.extra/ directory.
What's the usecase for this? This is supposed to be useful in context of
implementing fully trusted initrds, i.e. initrds that are not built
locally on the system and unsigned/unmeasured – as we do things
currently —, but instead are built by the vendor, and measured to TPM.
The idea is that a basic initrd is always linked into the kernel EFI
image anyway. This will already be sufficient for many cases. However,
in some cases it is necessary to parameterize initrds, or to extend the
basic initrds with additional subsystems (e.g. think complex storage, or
passing server info/certificates/… to initrds). The idea is that the
parameterization is done using the "credentials" logic we already have
in systemd, with these credential files (which can optionally be
encrypted+authenticated by TPM2) being placed in the ESP next to the
kernel image. And the initrd extension via the "sysext" logic we already
have in systemd too.
Note that the files read by this code are not verified immediately, they
are copied *as-is* and placed into /.extra/ in the initrd. In a trusted
environment they need to be validated later, but before first use. For
the credentials logic this should be done via the TPM2
encryption/authentication logic. For the sysext stuff the idea is that
this is done via signed images, as implemented by #20691.
We ship the mkosi files to make sure we can test our own code. A good
chunk of our code (and the main reason to use qemu rather than nspawn)
is the EFI code, i.e. in sd-boot and the EFI stub. Hence it's bad idea
to use qemu headless mode, since that means we bypass all that.
Let's hence toggle the defaults here, but keep the line in place, to
make it easy to switch back if someone wants the speed, rather than the
testing.
"bootctl update" tries to add sd-boot to the EFI boot loader list if it
is not already there. To do so, it uses find_slot() which finds the
proper BootXXXX slot ID to use and also returns 1 if an existing sd-boot
entry was found at this ID or 0 if it is a new unused ID. In "update"
case install_variables() only writes the entry in case 0 (no existing
entry).
However, find_slot() erroneously returns 1 if it finds a gap in the Boot
IDs (i.e. when not resorting to max(ids) + 1). This causes
"bootctl update" to not add a missing systemd-boot boot entry if the
existing BootXXXX entry IDs are not consecutive.
Fix that by returning 0 in find_slot() when an empty gap ID is selected
to make it match the behavior when selecting an empty non-gap ID.
