We don't have plural in the name of any other -util files and this
inconsistency trips me up every time I try to type this file name
from memory. "formats-util" is even hard to pronounce.
Let's make sure that our loopback files remain sparse, hence let's set
"discard" as mount option on file systems that support it if the backing device
is a loopback.
036d523641
> vfs: Don't create inodes with a uid or gid unknown to the vfs
It is expected that filesystems can not represent uids and gids from
outside of their user namespace. Keep things simple by not even
trying to create filesystem nodes with non-sense uids and gids.
So, we actually should `reset_uid_gid` early to prevent https://github.com/systemd/systemd/pull/4223#issuecomment-252522955
$ sudo UNIFIED_CGROUP_HIERARCHY=no LD_LIBRARY_PATH=.libs .libs/systemd-nspawn -D /var/lib/machines/fedora-rawhide -U -b systemd.unit=multi-user.target
Spawning container fedora-rawhide on /var/lib/machines/fedora-rawhide.
Press ^] three times within 1s to kill container.
Child died too early.
Selected user namespace base 1073283072 and range 65536.
Failed to mount to /sys/fs/cgroup/systemd: No such file or directory
Details: https://github.com/systemd/systemd/pull/4223#issuecomment-253046519Fixes: #4352
This makes it easier to debug failed nspawn invocations:
Mounting sysfs on /var/lib/machines/fedora-rawhide/sys (MS_RDONLY|MS_NOSUID|MS_NOEXEC|MS_NODEV "")...
Mounting tmpfs on /var/lib/machines/fedora-rawhide/dev (MS_NOSUID|MS_STRICTATIME "mode=755,uid=1450901504,gid=1450901504")...
Mounting tmpfs on /var/lib/machines/fedora-rawhide/dev/shm (MS_NOSUID|MS_NODEV|MS_STRICTATIME "mode=1777,uid=1450901504,gid=1450901504")...
Mounting tmpfs on /var/lib/machines/fedora-rawhide/run (MS_NOSUID|MS_NODEV|MS_STRICTATIME "mode=755,uid=1450901504,gid=1450901504")...
Bind-mounting /sys/fs/selinux on /var/lib/machines/fedora-rawhide/sys/fs/selinux (MS_BIND "")...
Remounting /var/lib/machines/fedora-rawhide/sys/fs/selinux (MS_RDONLY|MS_NOSUID|MS_NOEXEC|MS_NODEV|MS_BIND|MS_REMOUNT "")...
Mounting proc on /proc (MS_NOSUID|MS_NOEXEC|MS_NODEV "")...
Bind-mounting /proc/sys on /proc/sys (MS_BIND "")...
Remounting /proc/sys (MS_RDONLY|MS_NOSUID|MS_NOEXEC|MS_NODEV|MS_BIND|MS_REMOUNT "")...
Bind-mounting /proc/sysrq-trigger on /proc/sysrq-trigger (MS_BIND "")...
Remounting /proc/sysrq-trigger (MS_RDONLY|MS_NOSUID|MS_NOEXEC|MS_NODEV|MS_BIND|MS_REMOUNT "")...
Mounting tmpfs on /tmp (MS_STRICTATIME "mode=1777,uid=0,gid=0")...
Mounting tmpfs on /sys/fs/cgroup (MS_NOSUID|MS_NOEXEC|MS_NODEV|MS_STRICTATIME "mode=755,uid=0,gid=0")...
Mounting cgroup on /sys/fs/cgroup/systemd (MS_NOSUID|MS_NOEXEC|MS_NODEV "none,name=systemd,xattr")...
Failed to mount cgroup on /sys/fs/cgroup/systemd (MS_NOSUID|MS_NOEXEC|MS_NODEV "none,name=systemd,xattr"): No such file or directory
The documentation says lists "yes", "no", "pick", and numeric arguments.
But parse_boolean was attempted first, so various numeric arguments were
misinterpreted.
In particular, this fixes --private-users=0 to mean the same thing as
--private-users=0:65536.
While at it, use strndupa to avoid some error handling.
Also give a better error for an empty UID range. I think it's likely that
people will use --private-users=0:0 thinking that the argument means UID:GID.
Current systemd version detection routine cannot detect systemd 230,
only systmed >= 231. This means that we'll still use the legacy hierarchy
in some cases where we wouldn't have too. If somebody figures out a nice
way to detect systemd 230 this can be later improved.
systemd-soon-to-be-released-232 is able to deal with the mixed hierarchy.
So make an educated guess, and use the mixed hierarchy in that case.
Tested by running the host with mixed hierarchy (i.e. simply using a recent
kernel with systemd from git), and booting first a container with older systemd,
and then one with a newer systemd.
Fixes#4008.
The new function has 416 lines by itself!
"return log_error_errno" is used to nicely reduce the volume of error
handling code.
A few minor issues are fixed on the way:
- positive value was used as error value (EIO), causing systemd-nspawn
to return success, even though it shouldn't.
- In two places random values were used as error status, when the
actual value was in an unusual place (etc_password_lock, notify_socket).
Those are the only functional changes.
There is another potential issue, which is marked with a comment, and left
unresolved: the container can also return 133 by itself, causing a spurious
reboot.
Previously, if ReadWritePaths= was nested inside a ReadOnlyPaths=
specification, then we'd first recursively apply the ReadOnlyPaths= paths, and
make everything below read-only, only in order to then flip the read-only bit
again for the subdirs listed in ReadWritePaths= below it.
This is not only ugly (as for the dirs in question we first turn on the RO bit,
only to turn it off again immediately after), but also problematic in
containers, where a container manager might have marked a set of dirs read-only
and this code will undo this is ReadWritePaths= is set for any.
With this patch behaviour in this regard is altered: ReadOnlyPaths= will not be
applied to the children listed in ReadWritePaths= in the first place, so that
we do not need to turn off the RO bit for those after all.
This means that ReadWritePaths=/ReadOnlyPaths= may only be used to turn on the
RO bit, but never to turn it off again. Or to say this differently: if some
dirs are marked read-only via some external tool, then ReadWritePaths= will not
undo it.
This is not only the safer option, but also more in-line with what the man page
currently claims:
"Entries (files or directories) listed in ReadWritePaths= are
accessible from within the namespace with the same access rights as
from outside."
To implement this change bind_remount_recursive() gained a new "blacklist"
string list parameter, which when passed may contain subdirs that shall be
excluded from the read-only mounting.
A number of functions are updated to add more debug logging to make this more
digestable.
This commit is a minor tweak after the split of `--share-system`, decoupling the `--boot`
option from IPC namespacing.
Historically there has been a single `--share-system` option for sharing IPC/PID/UTS with the
host, which was incompatible with boot/pid1 mode. After the split, it is now possible to express
the requirements with better granularity.
For reference, this is a followup to #4023 which contains references to previous discussions.
I realized too late that CLONE_NEWIPC is not strictly needed for boot mode.
This commit follows further on the deprecation path for --share-system,
by splitting and gating each share-able namespace behind its own
environment flag.
Currently, systemd uses either the legacy hierarchies or the unified hierarchy.
When the legacy hierarchies are used, systemd uses a named legacy hierarchy
mounted on /sys/fs/cgroup/systemd without any kernel controllers for process
management. Due to the shortcomings in the legacy hierarchy, this involves a
lot of workarounds and complexities.
Because the unified hierarchy can be mounted and used in parallel to legacy
hierarchies, there's no reason for systemd to use a legacy hierarchy for
management even if the kernel resource controllers need to be mounted on legacy
hierarchies. It can simply mount the unified hierarchy under
/sys/fs/cgroup/systemd and use it without affecting other legacy hierarchies.
This disables a significant amount of fragile workaround logics and would allow
using features which depend on the unified hierarchy membership such bpf cgroup
v2 membership test. In time, this would also allow deleting the said
complexities.
This patch updates systemd so that it prefers the unified hierarchy for the
systemd cgroup controller hierarchy when legacy hierarchies are used for kernel
resource controllers.
* cg_unified(@controller) is introduced which tests whether the specific
controller in on unified hierarchy and used to choose the unified hierarchy
code path for process and service management when available. Kernel
controller specific operations remain gated by cg_all_unified().
* "systemd.legacy_systemd_cgroup_controller" kernel argument can be used to
force the use of legacy hierarchy for systemd cgroup controller.
* nspawn: By default nspawn uses the same hierarchies as the host. If
UNIFIED_CGROUP_HIERARCHY is set to 1, unified hierarchy is used for all. If
0, legacy for all.
* nspawn: arg_unified_cgroup_hierarchy is made an enum and now encodes one of
three options - legacy, only systemd controller on unified, and unified. The
value is passed into mount setup functions and controls cgroup configuration.
* nspawn: Interpretation of SYSTEMD_CGROUP_CONTROLLER to the actual mount
option is moved to mount_legacy_cgroup_hierarchy() so that it can take an
appropriate action depending on the configuration of the host.
v2: - CGroupUnified enum replaces open coded integer values to indicate the
cgroup operation mode.
- Various style updates.
v3: Fixed a bug in detect_unified_cgroup_hierarchy() introduced during v2.
v4: Restored legacy container on unified host support and fixed another bug in
detect_unified_cgroup_hierarchy().
A following patch will update cgroup handling so that the systemd controller
(/sys/fs/cgroup/systemd) can use the unified hierarchy even if the kernel
resource controllers are on the legacy hierarchies. This would require
distinguishing whether all controllers are on cgroup v2 or only the systemd
controller is. In preparation, this patch renames cg_unified() to
cg_all_unified().
This patch doesn't cause any functional changes.
This removes the --share-system switch: from the documentation, the --help text
as well as the command line parsing. It's an ugly option, given that it kinda
contradicts the whole concept of PID namespaces that nspawn implements. Since
it's barely ever used, let's just deprecate it and remove it from the options.
It might be useful as a debugging option, hence the functionality is kept
around for now, exposed via an undocumented $SYSTEMD_NSPAWN_SHARE_SYSTEM
environment variable.
This has the benefit that the container can follow the host's DNS server
changes without us having to constantly update the container's resolv.conf
settings.
With this change we'll no longer write to /etc/machine-id from nspawn, as that
breaks the --volatile= operation, as it ensures the image is never considered
in "first boot", since that's bound to the pre-existance of /etc/machine-id.
The new logic works like this:
- If /etc/machine-id already exists in the container, it is read by nspawn and
exposed in "machinectl status" and friends.
- If the file doesn't exist yet, but --uuid= is passed on the nspawn cmdline,
this UUID is passed in $container_uuid to PID 1, and PID 1 is then expected
to persist this to /etc/machine-id for future boots (which systemd already
does).
- If the file doesn#t exist yet, and no --uuid= is passed a random UUID is
generated and passed via $container_uuid.
The result is that /etc/machine-id is never initialized by nspawn itself, thus
unbreaking the volatile mode. However still the machine ID configured in the
machine always matches nspawn's and thus machined's idea of it.
Fixes: #3611
We currently have code to read and write files containing UUIDs at various
places. Unify this in id128-util.[ch], and move some other stuff there too.
The new files are located in src/libsystemd/sd-id128/ (instead of src/shared/),
because they are actually the backend of sd_id128_get_machine() and
sd_id128_get_boot().
In follow-up patches we can use this reduce the code in nspawn and
machine-id-setup by adopted the common implementation.
Matching the behaviour of gpt-auto-generator, if we find an ESP while
dissecting a container image, mount it to /efi or /boot if those dirs exist and
are empty.
This should enable us to run "bootctl" inside a container and do the right
thing.
Normally we make all of /proc/sys read-only in a container, but if we do have
netns enabled we can make /proc/sys/net writable, as things are virtualized
then.
