Let's return the size in a return parameter instead of the return value.
And if NULL is specified this tells us the caller doesn't care about the
size and expects a NUL terminated string. In that case look for an
embedded NUL byte, and refuse in that case.
This should lock things down a bit, as we'll systematically refuse
embedded NUL strings now when we expect strings.
The capsule instances are related to user instances, so treat them
equally to user@.service when handling cgroup paths. This also saves us
from polluting public libsystemd API with variant for capsules too.
Fix: #36098
Supersedes #35308 (cherry-picked one commit and replaced the rest)
(I left a few comments that's folded by GitHub. Please make sure to
check them too.)
"nsenter -a" doesn't migrate the specified process into the target
cgroup (it really should). Thus the cgroup will remain in a cgroup
that is (due to cgroup ns) outside our visibility. The kernel will
report the cgroup path of such cgroups as starting with "/../". Detect
that and print a reasonably error message instead of trying to resolve
that.
cg_kill_kernel_sigkill() has a narrow use case, and currently
no code really reaches that branch. Let's detach it from
cg_kill_recursive() hence, and call it explicitly later
where appropriate.
When removing a cgroup, we always want to eliminate subcgroups
first, i.e. use cg_trim(). And cg_rmdir() (along with
CGROUP_REMOVE flag) is simply unused. Kill it.
Similar to the implementation of cgroup.kill in the kernel, let's
skip kernel threads in cg_kill_items() as trying to kill kernel
threads as an unprivileged process will fail with EPERM and doesn't
do anything when running privileged.
Opening pidfds for non thread group leaders only works from 6.9 onwards with PIDFD_THREAD. On
older kernels or without PIDFD_THREAD pidfd_open() fails with EINVAL. Since we might read non
thread group leader IDs from cgroup.threads, we introduce and set CGROUP_NO_PIDFD to avoid
trying open pidfd's for them and instead use the pid as is.
This is just like cg_is_delegate() but operates on an fd instead of a
cgroup path.
Sooner or later we should access cgroupfs mostly via fds rather than
paths, but we aren't there yet. But let's at least get started.
This setting indicates that the given unit wants to receive coredumps
for processes that crash within the cgroup of this unit. This setting
requires that Delegate= is also true, and therefore is only available
where Delegate= is available.
This will be used by systemd-coredump to support forwarding coredumps to
containers.
Jelle van der Waa
Daan De Meyer
Mike Yuan
Lennart Poettering
Michal Koutný
Yu Watanabe
Luca Boccassi
Zbigniew Jędrzejewski-Szmek
Timo Rothenpieler
Nick Rosbrook