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>
For some reason, the entity names configured in custom-entities.ent
used abbreviated names. This just creates unnecessary confusion, so update
to use the same name as the config dict.
Reword some surrounding sentences while at it.
The description of ME= said "see above", but it was actually above the other
one. So change the order. But while reading this, I found it very hard to
understand. So reword things, hopefully in a way that is easier to understand.
The current behaviour is rather complex and unintuitive, but this description
just tries to describe it truthfully.
Our baseline is v5.4 and cgroup v2 is enforced now,
which means CPU accounting is cheap everywhere without
requiring any controller, hence just remove the directive.
The option that systemd actually looks for has an underscore and no dash
as can be seen in src/core/main.c.
The man/kernel-command-line.xml documentation also gets it right with
this file being the only instance of watchdog-device being used.
Fixes: c75396c30b ("documentation: add description for watchdog device path")
Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
- Improve wording for explanation when these variables are inherited
- Clarify that these variables are not placed in the process environment block,
so /proc/PID/environ cannot be used as a debugging tool
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.
Same reason as the reload, reexec is disruptive and it requires the
same privileges, so if somebody wants to limit reloads, they'll also
want to limit reexecs, so use the same setting.
This adds a new ProtectSystem= setting that mirrors the option of the
same of services, but in a more restrictive way. If enabled will remount
/usr/ to read-only, very early at boot. Takes a special value "auto"
(which is the default) which is equivalent to true in the initrd, and
false otherwise.
Unlike the per-service option we don't support full/strict modes, but
the door is open to eventually support that too if it makes sense. It's
not entirely trivial though as we have very little mounted this early,
and hence the mechanism might not apply 1:1. Hence in this PR is a
conservative first step.
My primary goal with this is to lock down initrds a bit, since they
conceptually are mostly immutable, but they are unpacked into a mutable
tmpfs. let's tighten the screws a bit on that, and at least make /usr/
immutable.
This is particularly nice on USIs (i.e. Unified System Images, that pack
a whole OS into a UKI without transitioning out of it), such as
diskomator.
As pointed out in https://github.com/systemd/systemd/issues/29814, we need to
use phrases are are meaningful on their own, because the man page formatter
creates a list at the bottom. With <ulink>see docs</ulink>, we end up with:
NOTES:
1. see docs
https://some.url/page
2. see docs
https://some.url/page2
which is not very useful :(
Also, the text inside the tag should not include punctuation.
Python helper:
from xml_helper import xml_parse
for p in glob.glob('../man/*.xml'):
t = xml_parse(p)
ulinks = t.iterfind('.//ulink')
for ulink in ulinks:
if ulink.text is None: continue
text = ' '.join(ulink.text.split())
print(f'{p}: {text}')
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.
The order of the description of each item should match the order that they are declared. Un-document effect of deprecated non-unified CGroup hierarchy on
DefaultCPUAccounting=. Mention that the default value for DefaultCPUAccouting= is
affected by the kernel version.
This enables the ManagerEnvironment= settings in the user's user.conf to
reference some user data like $HOME for the purpose of setting
environment variables derived from these values.
This changes the PSI window duration we default to for watching memory
pressure events from 1s to 2s. This is because apparently the kernel
will soon disallow window durations other than 2s for unprivileged
processes.
Hence, we'll bump the threshold from 100m to 200ms, and the window from
1s to 2s.
For any user on a semi-recent kernel, effectively this setting is pointless.
We should deprecate it once not needed anymore for the v1 hierarchy. For
now, adjust the description.
Config options are -Ddefault-timeout-sec= and -Ddefault-user-timeout-sec=.
Existing -Dupdate-helper-user-timeout= is renamed to -Dupdate-helper-user-timeout-sec=
for consistency. All three options take an integer value in seconds. The
renaming and type-change of the option is a small compat break, but it's just
at compile time and result in a clear error message. I also doubt that anyone was
actually using the option.
This commit separates the user manager timeouts, but keeps them unchanged at 90 s.
The timeout for the user manager is set to 4/3*user-timeout, which means that it
is still 120 s.
Fedora wants to experiment with lower timeouts, but doing this via a patch would
be annoying and more work than necessary. Let's make this easy to configure.
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.
The general idea is that users should be able to figure out if some option
that they see in a config file or on some internet page is something that
systemd knows about. Once users know that, yes, this was an option but has
been deprecated and removed from the documentation, it's much easier for them
to find any docs in old versions if they want to. Or to switch to something
different.
DefaultSmackProcessLabel tells systemd what label to assign to its child
process in case SmackProcessLabel is not set in the service file. By
default, when DefaultSmackProcessLabel is not set child processes inherit
label from systemd.
If DefaultSmackProcessLabel is set to "/" (which is an invalid character
for a SMACK label) the DEFAULT_SMACK_PROCESS_LABEL set during compilation
is ignored and systemd act as if the option was unset.
This mirrors a similar check in Linux kernel 5.16
(9dcc38e2813e0cd3b195940c98b181ce6ede8f20) that raised the
RLIMIT_MEMLOCK to 8M.
This change does two things: raise the default limit for nspawn
containers (where we try to mimic closely what the kernel does), and
bump it when running on old kernels which still have the lower setting.
Fixes: #16300
See: https://lwn.net/Articles/876288/
Add support for managing and configuring watchdog pretimeout values if
the watchdog hardware supports it. The ping interval is adjusted to
account for a pretimeout so that it will still ping at half the timeout
interval before a pretimeout event would be triggered. By default the
pretimeout defaults to 0s or disabled.
The RuntimeWatchdogPreSec config option is added to allow the pretimeout
to be specified (similar to RuntimeWatchdogSec). The
RuntimeWatchdogPreUSec dbus property is added to override the pretimeout
value at runtime (similar to RuntimeWatchdogUSec). Setting the
pretimeout to 0s will disable the pretimeout.
Michal Sekletar
Christian Brauner
Daan De Meyer
Lennart Poettering
Nikolas Kyx
Zbigniew Jędrzejewski-Szmek
Yu Watanabe
Grimmauld
Mike Yuan
Ahmad Fatoum
Jan Engelhardt
Lennart Poettering
Winterhuman
Vladimir Panteleev
Daan De Meyer
Luca Boccassi
David Tardon
Abderrahim Kitouni
Sam Morris
Ronan Pigott
Dmitry V. Levin
Łukasz Stelmach
nl6720
Nishal Kulkarni
Curtis Klein
Franck Bui