This is not intended as a user guide, but to describe the generic security
posture of the UEFI components. Hence we do not publish it on systemd.io
but only in the repository.
The biggest reason for forcing bfd was the use of linker scrips. Since
we don't rely on those anymore we can lift the requirement.
The biggest issue is gold as it does not understand -static-pie. Given
that it's pretty much on life support it's safe to just declare it not
supported anymore.
Don't link addons with libefi as clang/lld is sometimes very eager to
include memset etc., causing needless binary bloat and link errors with
LTO.
Fixes: #29165
This makes the special PE sections available again in our output EFI
images.
Since the compiler provides no way to mark a section as not allocated,
we use GNU assembler syntax to emit the sections instead. This ensures
the section data isn't emitted twice as load segments will only contain
allocating input sections.
The main reason we need to apply a whole lot of logic to the section
conversion logic is because PE sections have to be aligned to the page
size (although, currently not even EDK2 enforces this). The process of
achieving this with a linker script is fraught with errors, they are a
pain to set up correctly and suck in general. They are also not
supported by mold, which requires us to forcibly use bfd, which also
means that linker feature detection is easily at odds as meson has a
differnt idea of what linker is in use.
Instead of forcing a manual ELF segment layout with a linker script we
just let the linker do its thing. We then simply copy/concatenate the
sections while observing proper page boundaries.
Note that we could just copy the ELF load *segments* directly and
achieve the same result. Doing this manually allows us to strip sections
we don't need at runtime like the dynamic linking information (the
elf2efi conversion is effectively the dynamic loader).
Important sections like .sbat that we emit directly from code will
currently *not* be exposed as individual PE sections as they are
contained within the ELF segments. A future commit will fix this.
The tool initially just measured the boot phase, but was subsequently
extended to measure file system and machine IDs, too. At AllSystemsGo
there were request to add more, and make the tool generically
accessible.
Hence, let's rename the binary (but not the pcrphase services), to make
clear the tool is not just measureing the boot phase, but a lot of other
things too.
The tool is located in /usr/lib/ and still relatively new, hence let's
just rename the binary and be done with it, while keeping the unit names
stable.
While we are at it, also move the tool out of src/boot/ and into its own
src/pcrextend/ dir, since it's not really doing boot related stuff
anymore.
The kernel loads the DTB from EFI before ExitBootServices():
https://github.com/torvalds/linux/blob/v6.5/drivers/firmware/efi/libstub/fdt.c#L245
DTBs can map and assign arbitrary memory ranges. The kernel refuses
to load one from the dtb= kernel command line parameter when secure
boot is enabled, as it's not safe. Let's do the same for type 1
entries, as they are unverified.
This only affects arm64 and riscv64, firmwares do not support DTB
on x86.
The implementations are not 100% overlapping, so use different identifiers, so
that revocations can be done independently. e.g.: a bug that affects only
sd-boot won't necessarily cause old UKIs to be revoked.
Previously we only logged our measurements to the journal. This is not a
great solution though, since regular logs are subject to rotation, which
is something we really cannot have for measurements (as it means we can
never reproduce the PCR values from the data). Hence, let's maintain an
explicit log.
Ideally, we'd just use the TCG Canonical Event Log format 1:1
(https://trustedcomputinggroup.org/resource/canonical-event-log-format/).
However it's not a perfect fit fo us, for various reasons. But let's
follow it (in its JSON incantation) as closely at it makes sense, so
that it can easily be converted to the full format by programs consuming
it.
Code comments explain where we deviate from the TCG CEL-JSON, and what
to do about it when reading the data.
This partially reverts 3c1eee5bed.
I thought that it is not necessary, but
https://mesonbuild.com/Reference-manual_functions.html#vcs_tag says:
> This method returns a custom_tgt should be used to signal dependencies if
> other targets use the file outputted by this.
>
> For example, if you generate a header with this and want to use that in a
> build target, you must add the return value to the sources of that build
> target. Without that, Meson will not know the order in which to build the
> targets.
We can use version_h directly, since we already have it.
Hopefully fixes https://github.com/systemd/systemd/issues/28994.
There's really no point in first extracting a command line from an UKI
to just pass it unmodified to the UKI. In particular as this is
systematically ignored in SecureBoot is enabled.
Let's drop this, so that unless the user actually edits the cmdline we
pass nothing to the invoked kernel.
Note that this low-key is a compat break, since the passed cmdline gets
measured. However, in the interest of minimized the difference between
systems with and without sd-boot to behave the same i think we should
suppress the command line anyway.
The use of vcs_tag was dropped in #28567, which results in builds having
stale version information once new commit are made.
This also fixes a case where CI builds would have no version information
because they are checked out without any tags for git-describe to use.
Additionally, use `--git-dir` now, as that particular issues seems to
have been fixed by now.
I always found it confusing that most of our TPM related definitions are
in tpm2-util.h, but the PCR names in tpm-pcr.h, without the "2". Let's
fix that and make this systematic, in particular as the definitions in
the file all start with TPM2_ already.
No code flow changes, just some renaming.
We so far maintained two places for symboic names for PCRs. One in
tpm2-util.h and one in tpm-pcr.h.
Let's unify this into one, i.e. move the full list from tpm2-util.h into
tpm-pcr.h, replacing the short list placed so far there.
Systematically prefix the definitions with TPM2_ or tpm2_, to follow how
we do this for all other defines in this context.
No change in behaviour, just unification of tables.
Let's make utf8_to_utf16() and utf16_to_utf8() a bit nicer to use by
adding shortcuts for common cases.
This is particularly relevant for utf16_to_utf8() since the
multiplication with 2 is easy to forget.
I couldn't get ctrl work properly over serial line/qemu. Hence, let's
add an alias for Ctrl-l: a simple Shift-l (i.e. uppercase L)
(Note that lowercase L will result in selection of the first Linux
entry, hence we stay away from that)
Let's modernize the function a bit, and make it return the string passed
in, as we usually do.
Most importanly though: also drop leading whitespace, not just trailing
whitespace.
"static inline" makes sense in .h files. But in .c files it's useless
decoration, the compiler should just make its own decisions there, and
it can do that.
hence, replace all remaining uses of "static line" by a simple" static"
in all .c files (but keep them in .h files, where they make sense)
The gnu-efi definition of the struct uses [1], our local one [0] to size
the filename array. Let's avoid an ambiguity and use offsetof() so that
this difference doesn't matter. Also, doing it this way makes very clear
to the read what happens here: it's a structure with a variable size
suffix.
The command is deprecated, as per NEWS of 254. Let's go one step further
and remove it from the help text and man page, so that people are not
inspired to use it at this time anymore.
This is how we usually have done this before: remove it from visibility,
but support it for a while still.
An array of Tpm2PCRValue objects effectively replaces a TPML_PCR_SELECTION
object combined with an array of (properly ordered) TPM2B_DIGEST objects.
Also update tpm2_calculate_sealing_policy() pin parameter to boolean use_pin,
since the function does not need to know the pin value, only if a pin is being
used.
Luca Boccassi
Lennart Poettering
Jan Janssen
Joerg Behrmann
Zbigniew Jędrzejewski-Szmek
Mike Yuan
Emanuele Giuseppe Esposito
Dan Streetman
Yu Watanabe