-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.
If everything points to the fact that TPM2 should work, but then the
driver fails to initialize we should handle this gracefully and not
cause failing services all over the place.
Fixes: #25700
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.
RUN_WITH_UMASK was initially conceived for spawning externals progs with the
umask set. But nowadays we use it various syscalls and stuff that doesn't "run"
anything, so the "RUN_" prefix has outlived its usefulness.
- rename function arguments for storing results, and support the case
that they are NULL,
- return earlier on error,
- always validate read size in efivar_get_uint32_le() and efivar_get_uint64_le().
Doing the reconnect dance on some real firmware creates huge delays on
boot. This should not be needed anymore as we now ask the firmware to
make console devices and xbootldr partitions available explicitly in a
more targeted fashion.
Fixes: #25510
The EFI shell will pass the entire command line to the application it
starts, which includes the file path of the stub binary. This prevents
us from using the built-in cmdline if the command line is otherwise
empty.
Fortunately, the EFI shell registers a protocol on any images it starts
this way. The protocol even lets us access the args individually, making
it easy to strip the stub path off.
Fixes: #25201
How to interpret the pixel format depends on the masks in the DIB header
(if present). Also, 16bpp (unlike 24bpp) can carry an alpha channel.
This was previously not accounted for.
sd-stub has an opportunity to handle the seed the same way sd-boot does,
which would have benefits for UKIs when sd-boot is not in use. This
commit wires that up.
It refactors the XBOOTLDR partition discovery to also find the ESP
partition, so that it access the random seed there.
This fixes some bugs that could lead to garbage getting appended to the
command line passed to the kernel:
1. The .cmdline section is not guaranteed to be NUL-terminated, but it
was used as if it was.
2. The conversion of the command line to ASCII that was passed to the
stub ate the NUL at the end.
3. LoadOptions is not guaranteed to be a NUL-terminated EFI string (it
really should be and generally always is, though).
This also fixes the inconsistent mangling of the command line. If the
.cmdline section was used ASCII controls chars (new lines in particular)
would not be converted to spaces.
As part of this commit, we optimize conversion for the generic code
instead of the (deprecated) EFI handover protocol. Previously we would
convert to ASCII/UTF-8 and then back to EFI string for the (now) default
generic code path. Instead we now convert to EFI string and mangle that
back to ASCII in the EFI handover protocol path.
Now that the random seed is used on virtualized systems, there's no
point in having a random-seed-mode toggle switch. Let's just always
require it now, with the existing logic already being there to allow not
having it if EFI itself has an RNG. In other words, the logic for this
can now be automatic.
Removing the virtualization check might not be the worst thing in the
world, and would potentially get many, many more systems properly seeded
rather than not seeded. There are a few reasons to consider this:
- In most QEMU setups and most guides on how to setup QEMU, a separate
pflash file is used for nvram variables, and this generally isn't
copied around.
- We're now hashing in a timestamp, which should provide some level of
differentiation, given that EFI_TIME has a nanoseconds field.
- The kernel itself will additionally hash in: a high resolution time
stamp, a cycle counter, RDRAND output, the VMGENID uniquely
identifying the virtual machine, any other seeds from the hypervisor
(like from FDT or setup_data).
- During early boot, the RNG is reseeded quite frequently to account for
the importance of early differentiation.
So maybe the mitigating factors make the actual feared problem
significantly less likely and therefore the pros of having file-based
seeding might outweigh the cons of weird misconfigured setups having a
hypothetical problem on first boot.
For some firmware, replacing their own security arch instance with our
override using ReinstallProtocolInterface() is not enough as they will
not use it. This commit goes back to how this was done before by
directly modifying the security protocols.
Fixes: #25336
If the device path to text protocol is not available (looking angrily at
Apple) we would fail to boot because we cannot get the loaded image
path. As this is only used for cosmetic purposes, we can just silently
continue.
Fixes: #25363
Follow-up for #25368.
Let's consider ENOENT an expected error, and just debug log about it
(though, let's suffix it with `, ignoring.`). All other errors will log
loudly, as they are unexpected errors.
systemd-boot expects being loaded from ESP and is quite unhappy in case
the loaded image device path is something else. When running on qemu
this can easily happen though. Case one is direct kernel boot, i.e.
loading via 'qemu -kernel systemd-bootx64.efi'. Case two is sd-boot
being added to the ovmf firmware image and being loaded from there.
This patch detects both cases and goes inspect all file systems known to
the firmware, trying to find the ESP. When present the
VMMBootOrderNNNN variables are used to inspect the file systems in the
given order.
Rather than passing seeds up to userspace via EFI variables, pass seeds
directly to the kernel's EFI stub loader, via LINUX_EFI_RANDOM_SEED_TABLE_GUID.
EFI variables can potentially leak and suffer from forward secrecy
issues, and processing these with userspace means that they are
initialized much too late in boot to be useful. In contrast,
LINUX_EFI_RANDOM_SEED_TABLE_GUID uses EFI configuration tables, and so
is hidden from userspace entirely, and is parsed extremely early on by
the kernel, so that every single call to get_random_bytes() by the
kernel is seeded.
In order to do this properly, we use a bit more robust hashing scheme,
and make sure that each input is properly memzeroed out after use. The
scheme is:
key = HASH(LABEL || sizeof(input1) || input1 || ... || sizeof(inputN) || inputN)
new_disk_seed = HASH(key || 0)
seed_for_linux = HASH(key || 1)
The various inputs are:
- LINUX_EFI_RANDOM_SEED_TABLE_GUID from prior bootloaders
- 256 bits of seed from EFI's RNG
- The (immutable) system token, from its EFI variable
- The prior on-disk seed
- The UEFI monotonic counter
- A timestamp
This also adjusts the secure boot semantics, so that the operation is
only aborted if it's not possible to get random bytes from EFI's RNG or
a prior boot stage. With the proper hashing scheme, this should make
boot seeds safe even on secure boot.
There is currently a bug in Linux's EFI stub in which if the EFI stub
manages to generate random bytes on its own using EFI's RNG, it will
ignore what the bootloader passes. That's annoying, but it means that
either way, via systemd-boot or via EFI stub's mechanism, the RNG *does*
get initialized in a good safe way. And this bug is now fixed in the
efi.git tree, and will hopefully be backported to older kernels.
As the kernel recommends, the resultant seeds are 256 bits and are
allocated using pool memory of type EfiACPIReclaimMemory, so that it
gets freed at the right moment in boot.
Yu Watanabe
Lennart Poettering
Zbigniew Jędrzejewski-Szmek
Jan Janssen
Luca Boccassi
Jason A. Donenfeld
Li kunyu
Gerd Hoffmann