With the previous changes the modes for /tmp/ and /var/tmp/
may come in arbitrary directions, i.e. we may downgrade one
and upgrade another. Hence let's refactor the setup logic
a bit so they're truly independent.
As in the previous commit, checking for both requirements and ordering seems
unnecessary. In practical cases, the mount will be pulled in by the rest
of the transaction, so ordering is the part that matters. (The setup is
racy without the ordering.) If we drop the second check, the admin can
just use After=tmp.mount to achieve the desired behaviour, without needing
to explicitly pull in the unit. This is easier to configure and more robust.
This changes the implementation introduced in
6156bec7a4.
Also actually describe the implemented behaviour in the man page.
In https://github.com/systemd/systemd/issues/28515, multiple people report that
services that have PrivateTmp=yes and DefaultDependencies=no fail to create the
temporary directories under /tmp, when /tmp is e.g. a bind mount or some other
kind of mount that takes more time.
Before PrivateTmp=disconnected was added, we didn't have a nice solution:
DefaultDependencies=no is used to start services very early, so we wouldn't
want to add a dependency on /tmp automatically. With PrivateTmp=disconnected we
have a fairly nice solution. Let's "upgrade" to this mode automatically.
Strictly speaking, it is a small compat break, but in practice it's unlikely to
matter for early-boot services whether their /tmp is private or disconnected.
The dependency on /tmp that is checked is After. I think this is enough,
since any tmp.mount would be pulled in by local-fs.target and the rest of
the transaction anyway, so we don't need to check more than After.
The asserts are relaxed, because now the two settings can now diverge
in either way.
Resolves https://github.com/systemd/systemd/issues/28515.
[yhndnzj: fix unit_add_exec_dependencies() to handle the new
combination; add a comment in exec_needs_sys_admin()]
The only reason why ExecSharedRuntime.(var_)tmp_dir might
be suppressed is when (/var)/tmp/ is listed in InaccessiblePaths=,
in which case mount namespace is needed anyways. Moreover,
the current logic imposes a chicken-and-egg problem:
at various places in pid1 we'd need to check whether
the unit runs in a mountns, but the ExecSharedRuntime
may not be allocated for it just yet.
* Make sure we're not passing NULL to rmdir()
* Remove the inner "tmp" subdir as well, so that callers
can handle this transparently (e.g. exec_shared_runtime_make()
is not aware of the nested rmdir() requirements)
While at it, remove unneeded PROTECT_ERRNO.
These syscalls are part of a newer kernel API to replace interaction
with /proc/self/attr, with the goal of allowing LSM stacking. These are
being used now by e.g. libapparmor, so should be more easily available
to services using seccomp filtering.
We expose this via --private-users-delegate= which takes the number of
ranges to delegate. On top of delegating the ranges, we also mount in
the nsresourced socket and the mountfsd socket so that nested containers
can use nsresourced to allocate from the delegated ranges and mountfsd to
mount images.
Finally, we also create /run/systemd/dissect-root with systemd-tmpfiles to
make sure it is always available as unpriv users won't be able to create it
themselves.
test_sd_device_enumerator_filter_subsystem hangs forever in OBS builds,
as it waits for the udev queue to be drained. But this is not a booted
system, with systemd and udev, so nothing will do that.
Skip the test in that case.
ENOENT means /dev/loop-control isn't there which means we're in a
container and should go via mountfsd.
At the same time, reverse the check for fatal actions as almost all
actions can be done via mountfsd, only --attach needs the loop device.
- Allow foreign UID range
- Allow delegated UID ranges
Both of these can now be mapped by nsresourced into user namespaces
and hence should be accepted by mountfsd.
Whenever delegating UID ranges to a user namespace, it can also be
useful to map the foreign UID range, so that the container running in
the user namespace with delegated UID ranges can download container
images and unpack them to the foreign UID range.
Let's add an option mapForeign to make this possible. Note that this option
gives unprivileged users full access to the any foreign UID range owned directory
that they can access. Hence it is recommended (and already was recommended) to
store foreign UID range owned directories in a 0700 directory owned by the
owner of the tree to avoid access and modifications by other users.
This is already the case for the main users of the foreign UID range,
namely /var/lib/machines, /var/lib/portables and /home/<user> which all
use 0700 as their mode.
Users will also be able to create foreign UID range owned inodes in any
directories their own user can write to (on most systems this means /tmp,
/var/tmp and /home/<user>).
mkosi does all of its environment setup in an unprivileged user
namespace with an identity mapping. When it invokes nspawn and nspawn
tries to get a transient userns from nsresourced, this fails as no
transient ranges are mapped into mkosi's unprivileged userns (as doing
so would require privileges).
To fix this problem, let's allow allocating unprivileged self user
namespaces in nsresourced, similar to what the kernel allows, except that
we also support delegations for these. This means that mkosi can get its
unprivileged userns as before from nsresourced, but it can also request a
delegated 64K range inside that userns as well, which nsresourced can then
allocate to nspawn later when it asks for one.
Similar to the kernel, we disallow setgroups for self mappings. However,
instead of doing this via /proc/self/setgroups, which applies to the current
user namespace and all its child user namespaces, we use the BPF LSM to deny
setgroups instead, so that it can still be allowed for child user namespaces.
We need this because as soon as a container launches in a child user namespace
using one of the delegated mappings, it has to be able to do setgroups() to be
able to function properly.
To allow mapping the root user, we need to add the CAP_SETFCAP capability to
nsresourced.
We want to support the scenario where we bind mount the nsresourced
varlink socket into a container to allow nested containers where the
outer container runs in its own transient range from nsresourced but
can still allocate transient ranges for its own nested containers.
To support this use case let's add support for delegation. Delegated
ranges are allocated when allocating the primary range and are propagated
1:1 to the user namespace. We track delegated ranges in ".delegate" files
in the userns registry so that they can't be used for other range allocations.
We make one exception for delegated ranges though, if we get a request from
a user namespace that is a child of the user namespace that owns the delegated
ranges, we allow allocating from the delegated range. The parent userns already
has full ownership over the child userns, so it doesn't matter that the parent
userns and the child userns share the same range. This allows making use of
delegated ranges without having to run another copy of nsresourced inside the
parent userns to hand out from the delegated range.
To support recursive delegations, we keep track of the previous owners of the
delegated range and restore ownership to the last previous owner when the current
owner is freed.
The purpose of the userns-restrict BPF-LSM program is to prevent the
transient ranges leaking to disk, so let's allow operations outside the
transient UID ranges, even if the mount is not allowlisted.
This is preparation for the next commits where we'll add support for mapping
the current user and the foreign UID range into the user namespaces provisioned
by nsresourced. Operations creating files/directories as these UIDs/GIDs should
not need the corresponding mount to be allowlisted with nsresourced.
The callback might drop the last ref to the slot object, and we still
want to access it. Hence do what we usually do in these cases: keep an
extra reference while processing the callback.
This reverts commit 351b4dd123.
I'm pretty sure we should not create more of these multiplexer
interfaces, which in this specific also leads to a fair bit of
confusion: start/stop/reload-or-restart --marked all enqueue
all job types.
Instead, a dedicated verb will be introduced in later commits.
With v259, resolved can be used to replace Avahi for mDNS service
discovery and announcement. One key difference in the API is that Avahi
by default browses on all available interfaces by passing a special
`AVAHI_IF_UNSPEC` (-1) interface index value. With this change, passing
ifindex value `0` can be used to achieve the same , so this will work:
```
# Browse on all available interfaces
varlinkctl call --more unix:/run/systemd/resolve/io.systemd.Resolve \
io.systemd.Resolve.BrowseServices \
'{"domain":"local","type":"_display._tcp","ifindex":0,"flags":0}'
```
Not having to iterate through all interfaces on the client side then
also makes it more straight forward to build a resolve-avahi-compat
library for painlessly replacing Avahi with systemd-resolved.
A PoC compat lib requiring this change is available at
https://github.com/LorbusChris/resolve-avahi-compat
Currently, there's no way for a desktop environment to detect when a
systemd inhibitor has been added or removed. This means that a desktop
environment that wishes to show current inhibitors to the user will be
either forced to poll systemd or just use stale data.
Now, the desktop can listen for changed events on NCurrentInhibitors and
call GetInhibitors() in response to that.
Desktops cannot currently tell the difference between a power action
being set to challenge permanently (i.e. because the sysadmin wanted to
restrict the given user) and a power action being set to challenge
because it's temporarily inhibited.
Thus, a desktop might take an action that is valid in the first case but
not the second case. For instance: GNOME hides all of its automatic
suspend settings from the UI whenever a sleep inhibitor is active.
This now returns a new state: "inhibited". It communicates to the
desktop that the action is available normally, but at the moment the
desktop isn't allowed to perform the action due to an inhibitor.
Related: https://github.com/systemd/systemd/issues/37311
Now that it’s been replaced by `Acquire()` and `Install()`, there’s no
need to expose it as a separate method. Wrappers around `sysupdated` can
still expose an ‘update’ convenience verb by calling those two methods.
Signed-off-by: Philip Withnall <pwithnall@gnome.org>
Helps: https://github.com/systemd/systemd/issues/34814
Rather than calling `Update()`. This should allow us to eventually drop
`Update()`.
This should just be an internal change, and should not result in any
user-visible changes to the behaviour of `updatectl update`.
Signed-off-by: Philip Withnall <pwithnall@gnome.org>
Helps: https://github.com/systemd/systemd/issues/34814
Daan De Meyer
Mike Yuan
Zbigniew Jędrzejewski-Szmek
Nick Rosbrook
Daan De Meyer
Luca Boccassi
Antonio Alvarez Feijoo
Lennart Poettering
Yu Watanabe
Adrian Vovk
Zbigniew Jędrzejewski-Szmek
Philip Withnall