gethostname(3) says it's unspecified whether the string is properly terminated
when the hostname is too long. We created a buffer with one extra byte, and it
seems the intent was to let that byte serve as terminator even if we get an
unterminated string from gethostname().
No functional change, just moving a bunch of things around. Before
we needed a rather complicated setup to test hostname_setup(), because
the code was in src/core/. When things are moved to src/shared/
we can just test it as any function.
The test is still "unsafe" because hostname_setup() may modify the
hostname.
The semantics were significantly changed in c779a44222
("hostnamed: Fix the way that static and transient host names interact", Feb. 2014),
but when the dbus api documentation was imported much later, it wasn't properly
adjusted to describe those new semantics.
34293dfafd which added systemd.hostname= also
added new behaviour.
Let's ove various bits and pieces around so that they are in more appropriate
places. Drop recommendations to set the hostname for DHCP or mDNS purposes.
Nowadays we expect tools that want to expose some different hostname to the
outside to manage that internally without affecting visible state. Also drop
mentions of DHCP or mDNS directly setting the hostname, since nowadays network
management software is expected to (and does) go through hostnamed.
Also, add a high-level description of semantics. It glosses over the details of
handling of localhost-style names. Later commits will remove this special handling
anyway.
Upgrading to qemu 5.2 breaks TEST-36-NUMAPOLICY like:
qemu-system-x86_64: total memory for NUMA nodes (0x0) should
equal RAM size (0x20000000)
Use the new (as in >=2014) form of memdev in test 36:
-object memory-backend-ram,id=mem0,size=512M -numa node,memdev=mem0,nodeid=0
Since some target systems are as old as qemu 1.5.3 (CentOS7) but the new
kind to specify was added in qemu 2.1 this needs to add version parsing and
add the argument only when qemu is >=5.2.
Fixes#17986.
Signed-off-by: Christian Ehrhardt <christian.ehrhardt@canonical.com>
Previously, we'd already have explicit logging for the case where
$XDG_RUNTIME_DIR is not set. Let's also add some explicit logging for
the EPERM/ACCESS case. Let's also in both cases suggest the
--machine=<user>@.host syntax.
And while we are at it, let's remove side-effects from the macro.
By checking for both the EPERM/EACCES case and the $XDG_RUNTIME_DIR case
we will now catch both the cases where people use "su" to issue a
"systemctl --user" operation, and those where they (more correctly, but
still not good enough) call "su -".
Fixes: #17901
So far, the bridge always acted as if "--system" was used, i.e. would
unconditionally connect to the system bus. Let's add "--user" too, to
connect to the users session bus.
This is mostly for completeness' sake.
I wanted to use this when making sd-bus's ability to connect to other
user's D-Bus busses work, but it didn't exist so far. In the interest of
keeping things compatible the implementation in sd-bus will not use the
new "--user" switch, and instead manually construct the right bus path
via "--path=", but we still should add the proper switches, as
preparation for a brighter future, one day.
This is unfortunately harder to implement than it sounds. The user's bus
is bound a to the user's lifecycle after all (i.e. only exists as long
as the user has at least one PAM session), and the path dynamically (at
least theoretically, in practice it's going to be the same always)
generated via $XDG_RUNTIME_DIR in /run/.
To fix this properly, we'll thus go through PAM before connecting to a
user bus. Which is hard since we cannot just link against libpam in the
container, since the container might have been compiled entirely
differently. So our way out is to use systemd-run from outside, which
invokes a transient unit that does PAM from outside, doing so via D-Bus.
Inside the transient unit we then invoke systemd-stdio-bridge which
forwards D-Bus from the user bus to us. The systemd-stdio-bridge makes
up the PAM session and thus we can sure tht the bus exists at least as
long as the bus connection is kept.
Or so say this differently: if you use "systemctl -M lennart@foobar"
now, the bus connection works like this:
1. sd-bus on the host forks off:
systemd-run -M foobar -PGq --wait -pUser=lennart -pPAMName=login systemd-stdio-bridge
2. systemd-run gets a connection to the "foobar" container's
system bus, and invokes the "systemd-stdio-bridge" binary as
transient service inside a PAM session for the user "lennart"
3. The systemd-stdio-bridge then proxies our D-Bus traffic to
the user bus.
sd-bus (on host) → systemd-run (on host) → systemd-stdio-bridge (in container)
Complicated? Well, to some point yes, but otoh it's actually nice in
various other ways, primarily as it makes the -H and -M codepaths more
alike. In the -H case (i.e. connect to remote host via SSH) a very
similar three steps are used. The only difference is that instead of
"systemd-run" the "ssh" binary is used to invoke the stdio bridge in a
PAM session of some other system. Thus we get similar implementation and
isolation for similar operations.
Fixes: #14580
So far when asked for augmented bus credentials and the process was
already gone we'd fail fatally. Let's make this graceful instead, and
never allow augmenting fail due to PID having vanished — unless the
augmenting is the explicit and only purpose of the requested operation.
This should be safe as clients have to explicitly query the acquired
creds anyway and handle if they couldn't be acquired. Moreover we
already handle permission problems gracefully, thus clients must be
ready to deal with missing creds.
This is useful to make selinux authorization work for short-lived client
proceses. PReviously we'd augment creds to have more info to log about
(the selinux decision would not be based on augmented data however,
because that'd be unsafe), and would fail if we couldn't get it. Now,
we'll try to acquire the data, but if we cannot acquire it, we'll still
do the selinux check, except that logging will be more limited.
Let's clean up hostname_is_valid() a bit: let's turn the second boolean
argument into a more explanatory flags field, and add a flag that
accepts the special name ".host" as valid. This is useful for the
container logic, where the special hostname ".host" refers to the "root
container", i.e. the host system itself, and can be specified at various
places.
let's also get rid of machine_name_is_valid(). It was just an alias,
which is confusing and even more so now that we have the flags param.
The immediately following container_get_leader() call validate the name
anyway, no need to twice exactly the same way twice immediately after
each other.
Use symlink_atomic_label() instead of symlink_atomic() as the symlink
may need a different label than the parent directory.
Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com>
Zbigniew Jędrzejewski-Szmek