Add a new RestrictFileSystemAccess= boolean setting in the [Manager] section of
system.conf that enforces execution only from signed dm-verity block
devices and the initramfs during early boot.
When RestrictFileSystemAccess=yes is set, PID1 loads a BPF LSM program early in boot
that:
Integrity tracking (self-populating, no userspace involvement):
- bdev_setintegrity: records dm-verity signature status in a BPF hash
map when the kernel signals device integrity via
security_bdev_setintegrity()
- bdev_free_security: removes devices from the map on teardown
Execution enforcement (deny-default policy):
- bprm_check_security: blocks execve() from untrusted sources
- mmap_file: blocks PROT_EXEC mmap (shared libs, anonymous exec memory)
- file_mprotect: blocks W->X transitions (JIT, libffi, etc.)
Trust anchors:
- Signed dm-verity volumes (sig_valid flag in the BPF map)
- Initramfs (s_dev captured at load time, cleared after switch_root)
- Everything else is denied (tmpfs, procfs, sysfs, anonymous PROT_EXEC)
PID1 requires dm-verity require_signatures=1 to be enabled and refuses
to load the BPF program otherwise, ensuring the kernel enforces that all
dm-verity devices carry valid signatures.
After attach, PID1 extracts owned FDs from the skeleton (link FDs +
.bss map FD) and lets the skeleton be destroyed. The dup'd link FDs
keep programs attached via the kernel reference chain (link FD ->
bpf_link -> bpf_prog -> bpf_map). Destroying the skeleton unmaps the
.bss page from PID1's address space so no BPF state is readable via
/proc/1/mem. The .bss map FD is retained for targeted writes (clearing
initramfs_s_dev after switch_root via mmap).
Signed-off-by: Christian Brauner <brauner@kernel.org>
Exposed in the dracut testsuite while adding tests for sysexts:
```
[ 2.972948] localhost (sd-merge)[510]: Validation of dm-verity signature failed via the kernel, trying userspace validation instead: Required key not available
[ 2.972993] localhost (sd-merge)[510]: Skipping file '/etc/verity.d/dracut.pem', suffix is not '.crt'.
[ 2.973045] localhost (sd-merge)[510]: No userspace dm-verity certificates found.
```
While it is possible to disable sysext/confext merging in the main system
with 'systemctl disable', sysext/confext are always merged in the initrd,
both by systemd-{sys,conf}ext-initrd.service and by
systemd-{sys,conf}ext-sysroot.service and especially the latter can be
unexpected. Provide kernel cmdline options systemd.{sys,conf}ext=0 and
rd.systemd.{sys,conf}ext=0 covering all options.
So far we always conditioned our TPM magic on the UKI having detected
TPM support in the firmware. This is a bit limiting when we want to
support a software TPM that is not visible to the firmware. Hence let's
split this up, and add a separate control that can be set via the kernel
command line. However, as before, let's by default inherit the firmare
TPM discovery state into it, to retain the current behaviour unless
overriden.
With this in place, boot with "systemd.tpm2_measured_os=1
systemd.tpm2_software_fallback=1" on the kernel cmdline to get the swtpm
fallback and then a measured OS based on it.
We want to start the software TPM fallback only if no real hw is
evailable and if the user opts-in to this behaviour. Add a generator
that drives all this, based on kernel command line configuration.
This service's job is to talk to a VM associated IMDS service provided
by the local Cloud. It tries to abstract the protocol differences
various IMDS implementations implement, but does *not* really try to
abstract more than a few basic fields of the actual IMDS metadata.
IMDS access is wrapped in a Varlink API that local clients can talk to.
If possible this makes use of the IMDS endpoint information that has
been added to hwdb in the preceeding commit. However, endpoint info can
also be provided via kernel command line and credentials. For debugging
purposes we also accept them via environment variables and command line
arguments.
This adds a concept of early-boot networking, just enough to be able to
talk to the IMDS service. It is minimally configurable via a kernel
cmdline option (and a build-time option): the user may choose between
"locked" and "unlocked" mode. In the former mode direct access to IMDS via
HTTPS is blocked via a prohibit route (and thus all IMDS communication
has to be done via systemd-imdsd@.service). In the latter case no such
lockdown takes place, and IMDS may be acquired both via this new service
and directly. The latter is typically a good idea for compatibility with
current systems, the former is preferable for secure installations.
Access to IMDS fields is controlled via PK.
Found using linkchecker.
For virtiofsd, the man page is maintained upstream, but doesn't seem to be
available in any of the usual places. So let's link to the Debian version.
systemd.filter I have no idea what it is.
This introduces a bunch of facilities:
1. The factory-reset.target unit that requests a factory reset is now
complemented by factory-reset-now.target that executes it at next
boot.
2. This latter is added to the initial transaction via the new trivial
systemd-factory-reset-generator.
3. A tool systemd-factory-reset has been added to query, request,
cancel, complete factory reset operations (via EFI variables). Two of
these are wrapped into units that are plugged into
factory-reset.target and factory-reset-now.target respectively. The
tool also provides a simple Varlink API.
This should make things a lot cleaner, and both be useful as explicit
implementation on UEFI, and as template + hookpoints for alternative
implementations on non-UEFI.
This has been depracted since v254 (2023). Let's kill it for
good now, it has been long enough with 2y. Noone has shown up who wants
to keep it. And given it doesn't work in SB world anyway, and is not
measured is quite problematic security wise.
Introduce the `systemd.break=` kernel command line option to allow stopping the
boot process at a certain point and spawn a debug shell. After exiting this
shell, the system will resume booting.
It accepts the following values:
- `pre-udev`: before starting to process kernel uevents (initrd and host).
- `pre-basic`: before leaving early boot and regular services start (initrd and
host).
- `pre-mount`: before the root filesystem is mounted (initrd).
- `pre-switch-root`: before switching root (initrd).
Required for integration tests to power off on PID 1 crashes. We
deprecate systemd.crash_reboot and related options by removing them
from the documentation but still parsing them.
Most of our kernel cmdline options use underscores as word separators in
kernel cmdline options, but there were some exceptions. Let's fix those,
and also use underscores.
Since our /proc/cmdline parsers don't distinguish between the two
characters anyway this should not break anything, but makes sure our own
codebase (and in particular docs and log messages) are internally
consistent.
Let's allow configuring the debug tty independently of enabling/disabling
the debug shell. This allows mkosi to configure the correct tty while
leaving enabling/disabling the debug tty to the user.
This extends what systemd-firstboot does and runs on first boots only
and either processes user records passed in via credentials to create,
or asks the user interactively to create one (only if no regular user
exists yet).
As I noticed a lot of missing information when trying to implement checking
for missing info. I reimplemented the version information script to be more
robust, and here is the result.
Follow up to ec07c3c80b
This tries to add information about when each option was added. It goes
back to version 183.
The version info is included from a separate file to allow generating it,
which would allow more control on the formatting of the final output.
Doesn't really matter since the two unicode symbols are supposedly
equivalent, but let's better follow the unicode recommendations to
prefer greek small letter mu, as per:
https://www.unicode.org/reports/tr25
We already have the systemd.tty.xxx kernel cmdline arguments for
configuring tty's for services, let's make sure the term cmdline
argument applies to pid1 as well.
Let's allow configuring tty term and size using kernel cmdline arguments
so that when running in a VM we can communicate the terminal TERM and size
from the host via SMBIOS extra kernel cmdline arguments.
Note that this drops ProtectProc=invisible from
systemd-resolved.service.
This is done because othewise access to the booted "kernel" command line is not
necessarily available. That's because in containers we want to read
/proc/1/cmdline for that.
Fixes: #24103
Reloading is a heavy-weight operation, and currently it is not
possible to stop an orchestrator from spamming reload requests.
Add configuration options to allow rate-limiting.
