Let's make use of the new flag whenever we access the ESP or XBOOTLDR.
The resources we make use of in these partitions can't possibly use
symlinks (because UEFI knows no symlink concept), and they are untrusted
territory, hence under no circumstances we should be tricked into
following symlinks that shouldn't be there in the first place.
Of course, you might argue thta ESP/XBOOTLDR are VFAT and thus don#t
know symlinks. But the thing is, they don#t have to be. Firmware can
support other file systems too, and people can use efifs to gain access
to arbitrary Linux file systems from EFI. Hence, let's better be safe
than sorry.
I changed imports of util.h to initrd-util.h, or added an import of
initrd-util.h, to keep compilation working. It turns out that many files didn't
import util.h directly.
When viewing the patch, don't be confused by git rename detection logic:
a new .c file is added and two functions moved into it.
This moves the shim security arch override to the new
ReinstallProtocolInterface based interface. This also has the benefit to
reduce the time window in which we have this override active and also
actually removes it, which was not previously done.
The shim hooks themselves are also modernized too. The upcalls should
really not be neccessary if shim is happy with the provided binary.
Only the compat entry address is used now. This also now only returns
the compat entry address. If the image is native we do not need to try
calling into the entry address again as we would already have done so
from StartImage (and failed).
This is the proper way to start any EFI binary. The fact this even ever
worked was because the kernel does not have any PE relocations.
The only downside is that the embedded kernel image has to be signed and
trusted by the firmware under secure boot. A future commit will try to
deal with that.
This is really the parent image for the kernel that is to be run.
Renaming it as such prevents confusion with any image handles that are
about to be created.
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.
This fixes a regression introduced in e1636807 that removed setting this
value as it seemingly was not used by the kernel and would actively
break above 4G boots. But old kernels (4.18 in particular) will not boot
properly if it is not filled out by us.
The original issue was using the truncated value to then jump into the
kernel entry point, which we do not do anymore. So setting this value
again on newer kernels is fine.
The compiler may decide computations like these are not doing anything
and decide to optimize them away. This would defeat the whole fuzzing
exercise. This macro will force the compiler to materialize the value
no matter what. It should be less prone to accidents compared to using
log functions, which would either slow things down or still optimize the
value away (or simply move it into the if branch the log macros create).
The benefit over assert_se would be that no requirement is made on the
value itself. If we are fine getting a string of any size (including
zero), an assert_se would either create a noisy compiler warning about
conditions that would alawys be met or yet again optimize the whole
thing away.
We forgot to conditionalize this on pcrsig/pcrpkey too. So if you have
ne creds or sysext configured we actually wouldn't pass pcrsig/pcrpkey
along. Let's fix that.
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.)
The kernel PE image version can be used to detect support for this
feature, allowing us to prefer the generic code of the deprecated EFI
handover protocol.
We could try to relocate these but that is probably not needed. So far
we have not been bitten by this in the real world and kernels we boot
likely already support this anyway.
The boot params passed to the kernel only has to be one page in size
and the size of the setup header has to be calculated as it depends on
the boot protocol version supported by the kernel.
The kernel x86 boot protocol does not expect this value to be set when
using EFI handover protocol. If the stub is loaded above 4G we would
end up discarding the high bits, breaking boot.
Fixes: #24707
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.
Lennart Poettering
Zbigniew Jędrzejewski-Szmek
Jan Janssen
Yu Watanabe
Gerd Hoffmann
Luca Boccassi