We drop the optimization for verify_sigchld as the
check differs based on the options passed and the
extra syscalls are certainly not going to matter
compared to the cost of forking a child process.
Fixes#40166
This basically implements nss-myhostname, but natively in
systemd-resolved, so that the logic becomes available also for clients
using the local DNS stub for resolution or the D-Bus or Varlink APIs.
UID entry in the machine state file is introduced in v258,
hence when a host is upgraded to v258, the field does not exist in the
file, thus the variable 'uid' is NULL.
Follow-up for 276d200186.
Fixes#39061.
So far, machined strictly tracked the "leader" process of a machine,
i.e. the topmost process that is actually the payload of the machine.
Its runtime also defines the runtime of the machine, and we can directly
interact with it if we need to, for example for containers to join the
namespaces, or kill it.
Let's optionally also track the "supervisor" process of a machine, i.e.
the host process that manages the payload if there is one. This is
generally useful info, but in particular is useful because we might need
to communicate with it to shutdown a machine without cooperation of the
payload. Traditionally we did this by simply stopping the unit of the
machine, but this is not doable now that the host machined can be used
to track per-user machines.
In the long run we probably want a more bespoke protocol between
machined and supervisors (so that we can execute other commands too,
such as request cooperative reboots/shutdowns), but that's for later.
Some environments call the concept "monitor" rather than "supervisor" or
use some other term. I stuck to "supervisor" because nspawn uses this,
and ultimately one name is as good as another.
And of course, in other implementations of VM managers of containers
there might not be a single process tracking each VM/container. Because
of this, the concept of a supervisor is optional.
Now that unpriv clients can register machines, let's register their UID
too. This allows us to do two things:
1. make sure the scope delegation is assigned to the right UID (so that
the unpriv user can actually create cgroups below the delegated
scope)
2. permit certain types of access (i.e. killing, or pty access) to the
client without auth if it owns the machine.
Let's check the leader alive state, and let's log about dbus errors.
This mimics (but is not quite identical to) what we do these days in
logind for GC'ing user sessions.
We need to protect us from recycled PIDs here like everywhere else: once
we read data from /proc/$PID/ we need to validate that $PID still points
to the original pidfd.
This introduce LOG_ITEM() macro that checks arbitrary formats in
log_struct().
Then, drop _printf_ attribute from log_struct_internal(), as it does not
help so much, and compiler checked only the first format string.
Hopefully, this silences false-positive warnings by Coverity.
When copying files from or to a container we so far opened the host side
fd first, then entered the container (specifically, joined it's mount
namespace) in a forked off child process, and opened the other side
there, followed by the (potentially slow) copying from inside the
container mount namespace.
This commit changes this so that we rejoin the host mount namespace
before doing the copying routine. This is relevant, so that we can rely
on /proc/self/fd/… to work, which is not the case otherwise, as we'll
see /proc/ from a pidns that is not our own, in wich case
/proc/self/fd/… is refused. By moving back to the host mount namespace
our own pidns and the pidns the /proc/ mount belongs to will be in sync
again, and all is good.
This is in particular preparation for the next commit, that makes the
copy routine strictly depending on /proc/ being accessible and working.
After d8854ff1ac, if a serialized
leader PID of a machine is already dead when deserialized, then the
leader PID and PIDFD are unset for the machine, and subsequent
machine_start() -> machine_watch_pidfd() will trigger an assertion.
This makes a Machine object without leader PID GCed.
Fixes a bug introduced by the combination of
d8854ff1ac (v255) and
1762c2c045 (v257).
Fixes#35602.
Daan De Meyer
Daan De Meyer
Yu Watanabe
Lennart Poettering
Ivan Kruglov