Let's define a way how to mark codepaths that are subject to
deletion once the kernel baseline reaches a certain version, to make it
easier to find these cases.
WHile we are at it, introuce a whole section in CODING_STYLE about
kernel version compat.
I followed the new scheme in #39621, but we can merge the coding style
guidelines on this already.
This partially reverts commit e58ba80a40. Those
aliases were removed as part of the removal of sysvinit compat, but the removal
was immediately reported as a regression by users. In particular, users can
have one of those set as the default target, or use those names in Wants= or
Requires= dependencies. At least in Fedora, the removal was immediately
reverted.
When looking at our "portability and stability promise", I noticed that those
units are explicitly listed in the promise. Let's restore them upstream. They
are conditionalized under a new -Dcompat-sysv-interfaces=bool option, so that
downstreams like Arch that wasnt to strictly avoid legacy interfaces can easily
disable them. They are dropped from the docs, like we do for all deprecated
interfaces.
The kernel has a "don't break userspace" policy [1] which is very easy
to understand and like (even if the details are complicated). We had a
complicated policy statement, but the actual practice is that we'll
generally avoid changes that cause problems for users. So the whole
detailed table is more of a guideline than something that we can rely
on.
To improve public perception, and to align the docs with practice, let's
make a general promise to keep stability, and change the existing table
to a "guideline" that tells people which interfaces to use and which not
to use so that use and development of systemd don't conflict or create
pain.
The existing document was very long, and I think it'll have a bigger
impact if it shorter. In particular, the chart is dropped, because it
was of limited use and severly outdated, because we have added many new
interfaces and components without updating it. Adding the missing
elements (and then keeping it updated) would be a lot of effort. The
chart would be most useful to somebody trying to build a systemd
reimplementation, but there haven't been many attempts like this, so
let's save the work and drop it and make the document shorter.
I also dropped the mentions of Debian. Back in the day, we did indeed
adopt many Debian conventions for config files and such, but over the
years the scope of the project has grown quite a bit and that part
of systemd is a small fraction now. And we've adopted conventions
and ideas from many other places too, so we don't mention Debian
specifically.
[1] https://docs.kernel.org/admin-guide/reporting-regressions.html
I had to sketch this out before I could get the internals of
systemd-sysupdate straight in my head, particularly around how an
`UpdateSet` points to one `Instance` from each of a set of `Resource`s,
and those `Instance`s are either all sources or all targets.
Hopefully this is useful to the next person to look at the code.
Signed-off-by: Philip Withnall <pwithnall@gnome.org>
This does not yet support directory images properly
as systemd itself does not support unpriv directory
images properly yet.
The user profiles are a copy of the system profiles but without
DynamicUser=yes (can't be used by user managers) and without
ProtectHome=yes (this masks /home which breaks StateDirectory= which
is lcoated inside /home)
When setting SYSTEMD_LOG_LEVEL=debug and debugging a tool that happens
to do NSS lookups, the resulting logs from varlink are obnoxiously
verbose. Let's parse a separate log level environment variable in NSS
to allow overriding the log level for NSS specifically so these noisy
logs can be silenced.
In order to make "freeze" attacks against the update logic harder let's
add the ability to encode a "Best Before" date into SHA256SUMS directory
listings: if the current time is already beyond that time, we'll ignore
the SHA256SUMS as "stale" and fail the upgrade. Or in other words: the
freeze attack will now result in a client-side error eventually, instead
of success state.
The best before data is encoded in an optional pseudo-file listed in SHA256SUMS:
any file named BEST-BEFORE-YYYY-MM-DD.
As announced by a few releases now, finally drop support for
sysvinit scripts.
Keep rc-local generator for now, as it's really a distinct
feature even though from the same era.
We said in the header that "all EFI variables use the vendor UUID
4a67b082-0a4c-41cf-b6c7-440b29bb8c4f", but people not familiar with
UEFI might not know that this is concatenated with the variable name.
Let's use the full form once — when introducing the variable — to
make it easier to grep and search for.
While at it, use sembreaks in the document. This makes subsequent
changes much easier to review. (It also shows that some sentences
are rather long and thus hard to understand.)
meson test output is extremely verbose, printing
a separate line for each successful test. Let's
add -q/--quiet everywhere so it only prints full
lines for skipped and failed tests.
When a TTY is attached to the test unit, grep -q will generate SIGPIPE
for the previous command in the pipeline which in combo with `pipefail`
will cause the command to fail with exit status 141 which will fail the
test.
Replace with >/dev/null to avoid this from happening.
See also https://www.gnu.org/software/grep/manual/html_node/Usage.html
> There is a related problem with Bash’s set -e -o pipefail. Since grep
> does not always read all its input, a command outputting to a pipe read
> by grep can fail when grep exits before reading all its input, and the
> command’s failure can cause Bash to exit.
Co-authored-by: Yu Watanabe <watanabe.yu+github@gmail.com>
I was looking into a question posed in one of the Fedora discussion threads:
is it OK for a package to assume that files in different directories under /usr
are always on the same mount point? rpmlint emits a warning if a package has
files that are hardlinked between directories, i.e. rpmlint thinks that this
is not the case. But in practice, our systems are like this and our tooling
generally doesn't expect a part of /usr to be separated out. I looked at the
MOUNT_REQUIREMENTS document, but it doesn't answer this question clearly.
It was clearly written with the assumption that e.g. "/usr/" or "/var/" are one
mount point, so when it is "mounted", all of it is available. But the document
also talks about submounts being pulled in through requirements on specific
units, which requires some mounts not to be mounted all at once, so the reader
is left without any direct answer to this question.
This rewrite makes the following changes:
- rename "generally three categories of requirements" to
"three general categories of mount points" because we're categorizing
mount points, not requirements.
- always repeat the category name in further mentions,
e.g. "2/early" instead of just "2" so the reader doesn't have to jump
back to the table when reading.
- mention that it is OK for a mount point to be not split out
- say that submount which is "conceptually separate" may be mounted
later.
- say "ephemeral system" instead of "stateless system" and split out
the description of those systems into a separate paragraph and clearly
state that they are an exception that skips the requirements listed in
this document.
- be consistent in specifying the boundary before which each category must
have been mounted. Previously, cat. 1 was described as "before transisition"
and cat. 2 was described as "during early boot", which created the additional
problem that later we needed to contradict this saying that "must be mounted
during early boot" doesn't actually mean that and this can be done ealier.
If we say "before end of early boot", we avoid this awkwardness.
See https://gitlab.gnome.org/GNOME/glib/-/issues/2931 for the changes in
GLib upstream. Using `GMemoryMonitor` is now more compliant with the
systemd recommended approach, but it needs further work to read the
recommended environment variables rather than unconditionally accessing
the per-cgroup PSI kernel file directly.
Signed-off-by: Philip Withnall <pwithnall@gnome.org>
We do this in a separate service (rather than inside of
systemd-tpm2-setup), since we want failures of this measurement to
result in an instant reboot, like for most our measurements.
Failures to initialize nvpcrs, or allocate an SRK are somewhat OK (and
more likely), as long as this separator communicates clearly where they
have to have taken place, if they worked.
This locks down NvPCR initilization a bit more: we'll measure each
initialization of an NvPCR into PCR 9, thus chaining the NvPCRs to the
PCR set. After all NvPCRs are initialized we measure a barrier into PCR
9 as well.
This ensures that later additions of NvPCRs are clearly recognizable and
distuingishable from those done at boot.
Load modules in parallel using a pool of worker threads. The number of
threads is equal to the number of CPUs, with a maximum of 16 (to avoid
too many threads being started during boot on systems with many an high
core count, since the number of modules loaded on boot is usually on
the small side).
The number of threads can optionally be specified manually using the
SYSTEMD_MODULES_LOAD_NUM_THREADS environment variable; in this case,
no limit is enforced. If SYSTEMD_MODULES_LOAD_NUM_THREADS is set to 0,
probing happens sequentially.
Co-authored-by: Eric Curtin <ecurtin@redhat.com>
