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Let's introduce a common implementation of a function that checks
whether we are booted on a kernel with systemd-stub that has TPM PCR
measurements enabled. Do our own userspace measurements only if we
detect that.
PCRs are scarce and most likely there are projects which already make
use of them in other ways. Hence, instead of blindly stepping into their
territory let's conditionalize things so that people have to explicitly
buy into our PCR assignments before we start measuring things into them.
Specifically bind everything to an UKI that reported measurements.
This was previously already implemented in systemd-pcrphase, but with
this change we expand this to all tools that process PCR measurement
settings.
The env var to override the check is renamed to SYSTEMD_FORCE_MEASURE,
to make it more generic (since we'll use it at multiple places now).
This is not a compat break, since the original env var for that was not
included in any stable release yet.
This was dropped on reviewers' request in the revision that got merged,
but reference in two documents was not updated. Fix it.
Follow-up for: https://github.com/systemd/systemd/pull/25918
This commit adds support for attaching extra metadata to log
messages written to the journal via log.h. We keep track of a
thread local log context in log.c onto which we can push extra
metadata fields that should be logged. Once a field is no longer
relevant, it can be popped again from the log context.
On top of this, we then add macros to allow pushing extra fields
onto the log context.
LOG_CONTEXT_PUSH() will push the provided field onto the log context
and pop the last field from the log context when the current block
ends. LOG_CONTEXT_PUSH_STRV() will do the same but for all fields in
the given strv.
Using the macros is as simple as putting them anywhere inside a block
to add a field to all following log messages logged from inside that
block.
void myfunction(...) {
...
LOG_CONTEXT_PUSH("MYMETADATA=abc");
// Every journal message logged will now have the MYMETADATA=abc
// field included.
}
For convenience, there's also LOG_CONTEXT_PUSHF() to allow constructing
the field to be logged using printf() syntax.
log_context_new()/log_context_free() can be used to attach a log context
to an async operation by storing it in the associated userdata struct.
This is intended to be used with VSOCK, to notify the hypervisor/VMM, eg on the host:
qemu <...> -smbios type=11,value=io.systemd.credential:vmm.notify_socket=vsock:2:1234 -device vhost-vsock-pci,id=vhost-vsock-pci0,guest-cid=42
(vsock:2:1234 -> send to host on vsock port 1234, default is to send to 0 which is
the hypervisor itself)
Also on the host:
$ socat - VSOCK-LISTEN:1234,socktype=5
READY=1
STATUS=Ready.
The text said /dev/tty* as a whole was the VT subsystem and that VT is
not supported in containers.
But that's not accurate as /dev/tty* will match /dev/tty too and that
one device node is special and is not related to VT: it always points to
the current process own controlling tty, regardless what that is.
hence, rewrite /dev/tty* as /dev/tty[0-9]*.
When we dissect images automatically, let's be a bit more conservative
with the file system types we are willing to mount: only mount common
file systems automatically.
Explicit mounts requested by admins should always be OK, but when we do
automatic mounts, let's not permit barely maintained, possibly legacy
file systems.
The list for now covers the four common writable and two common
read-only file systems. Sooner or later we might want to add more to the
list.
Also, it might make sense to eventually make this configurable via the
image dissection policy logic.
-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.
Define new unit parameter (LogFilterPatterns) to filter logs processed by
journald.
This option is used to store a regular expression which is carried from
PID1 to systemd-journald through a cgroup xattrs:
`user.journald_log_filter_patterns`.
This is an octal number. We used the 0 prefix in some places inconsistently.
The kernel always interprets in base-8, so this has no effect, but I think
it's nicer to use the 0 to remind the reader that this is not a decimal number.
So, i think "erofs" is probably the better, more modern alternative to
"squashfs". Many of the benefits don't matter too much to us I guess,
but there's one thing that stands out: erofs has a UUID in the
superblock, squashfs has not. Having an UUID in the superblock matters
if the file systems are used in an overlayfs stack, as overlayfs uses
the UUIDs to robustly and persistently reference inodes on layers in
case of metadata copy-up.
Since we probably want to allow such uses in overlayfs as emplyoed by
sysext (and the future syscfg) we probably should ramp up our erofs game
early on. Hence let's natively support erofs, test it, and in fact
mention it in the docs before squashfs even.
- Mention "/please-review" in the contributing guide
- Remove "needs-rebase" on push
- Don't add "please-review" if a green label is set
- Don't add please-review label to draft PRs
- Add please-review when a PR moves out of draft
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.
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.
This is useful to force off fancy unicode glyph use (i.e. use "->"
instead of "→"), which is useful in tests where locales might be
missing, and thus control via $LC_CTYPE is not reliable.
Use this in TEST-58, to ensure the output checks we do aren't confused
by missing these glyphs being unicode or not.
This reverts commit 1f22621ba3.
As described in the reverted commit, we don't want to get rid of the check
completely. But the check requires opting-in by setting SYSTEMD_IN_INITRD=lenient,
which is cumbersome and doesn't seem to actually happen.
https://bugzilla.redhat.com/show_bug.cgi?id=2137631 is caused by systemd refusing
to treat the system as an initrd because overlayfs is used. Let's revert this
approach and do something that doesn't require opt-in instead.
I don't think it makes sense to keep support for "SYSTEMD_IN_INITRD=lenient" or
"SYSTEMD_IN_INITRD=auto". To get "auto" behaviour, just unset the option. And
"lenient" will be reimplemented as a better check. Thus the changes to the
option interface are completely reverted.
(s) is just ugly with a vibe of DOS. In most cases just using the normal plural
form is more natural and gramatically correct.
There are some log_debug() statements left, and texts in foreign licenses or
headers. Those are not touched on purpose.
