This adds two new settings BindPaths= and BindReadOnlyPaths=. They allow
defining arbitrary bind mounts specific to particular services. This is
particularly useful for services with RootDirectory= set as this permits making
specific bits of the host directory available to chrooted services.
The two new settings follow the concepts nspawn already possess in --bind= and
--bind-ro=, as well as the .nspawn settings Bind= and BindReadOnly= (and these
latter options should probably be renamed to BindPaths= and BindReadOnlyPaths=
too).
Fixes: #3439
This is relevant as many of the mounts we try to establish only can be followed
when some other prior mount that is a prefix of it is established. Hence: move
the symlink chasing into the actual mount functions, so that we do it as late
as possibly but as early as necessary.
Fixes: #4588
After all, these don#t strictly encapsulate bind mounts anymore, and we are
preparing this for adding arbitrary user-defined bind mounts in a later commit,
at which point this would become really confusing. Let's clean this up, rename
the BindMount structure to MountEntry, so that it is clear that it can contain
information about any kind of mount.
This reworks handling of the read-only management for mount points. This will
become handy as soon as we add arbitrary bind mount support (which comes in a
later commit).
Let's store the invocation ID in the per-service keyring as a root-owned key,
with strict access rights. This has the advantage over the environment-based ID
passing that it also works from SUID binaries (as they key cannot be overidden
by unprivileged code starting them), in contrast to the secure_getenv() based
mode.
The invocation ID is now passed in three different ways to a service:
- As environment variable $INVOCATION_ID. This is easy to use, but may be
overriden by unprivileged code (which might be a bad or a good thing), which
means it's incompatible with SUID code (see above).
- As extended attribute on the service cgroup. This cannot be overriden by
unprivileged code, and may be queried safely from "outside" of a service.
However, it is incompatible with containers right now, as unprivileged
containers generally cannot set xattrs on cgroupfs.
- As "invocation_id" key in the kernel keyring. This has the benefit that the
key cannot be changed by unprivileged service code, and thus is safe to
access from SUID code (see above). But do note that service code can replace
the session keyring with a fresh one that lacks the key. However in that case
the key will not be owned by root, which is easily detectable. The keyring is
also incompatible with containers right now, as it is not properly namespace
aware (but this is being worked on), and thus most container managers mask
the keyring-related system calls.
Ideally we'd only have one way to pass the invocation ID, but the different
ways all have limitations. The invocation ID hookup in journald is currently
only available on the host but not in containers, due to the mentioned
limitations.
How to verify the new invocation ID in the keyring:
# systemd-run -t /bin/sh
Running as unit: run-rd917366c04f847b480d486017f7239d6.service
Press ^] three times within 1s to disconnect TTY.
# keyctl show
Session Keyring
680208392 --alswrv 0 0 keyring: _ses
250926536 ----s-rv 0 0 \_ user: invocation_id
# keyctl request user invocation_id
250926536
# keyctl read 250926536
16 bytes of data in key:
9c96317c ac64495a a42b9cd7 4f3ff96b
# echo $INVOCATION_ID
9c96317cac64495aa42b9cd74f3ff96b
# ^D
This creates a new transient service runnint a shell. Then verifies the
contents of the keyring, requests the invocation ID key, and reads its payload.
For comparison the invocation ID as passed via the environment variable is also
displayed.
This patch ensures that each system service gets its own session kernel keyring
automatically, and implicitly. Without this a keyring is allocated for it
on-demand, but is then linked with the user's kernel keyring, which is OK
behaviour for logged in users, but not so much for system services.
With this change each service gets a session keyring that is specific to the
service and ceases to exist when the service is shut down. The session keyring
is not linked up with the user keyring and keys hence only search within the
session boundaries by default.
(This is useful in a later commit to store per-service material in the keyring,
for example the invocation ID)
(With input from David Howells)
This add a new message id for the end of user instance startup.
User manager startup is a different beast then the system startup.
Their descriptions are completely different too. Let's just separate
them.
Partially fixes#3351.
Also remove "successful" from the description, since we don't know if
the startup was successful or not.
%c and %r rely on settings made in the unit files themselves and hence resolve
to different values depending on whether they are used before or after Slice=.
Let's simply deprecate them and drop them from the documentation, as that's not
really possible to fix. Moreover they are actually redundant, as the same
information may always be queried from /proc/self/cgroup and /proc/1/cgroup.
(Accurately speaking, %R is actually not broken like this as it is constant.
However, let's remove all cgroup-related specifiers at once, as it is also
redundant, and doesn't really make much sense alone.)
Let's permit specifier expansion at a numbre of additional fields, where
arbitrary strings might be passed where this might be useful one day. (Or at
least where there's no clear reason where it wouldn't make sense to have.)
For settings that are not taking unit names there's no reason to use
unit_name_printf(). Use unit_full_printf() instead, as the names are validated
anyway in one form or another after expansion.
unit_name_printf() is usually what we use when the resulting string shall
qualify as unit name, and it hence avoids resolving specifiers that almost
certainly won't result in valid unit names.
Add a couple of more specifiers that unit_full_printf() resolves also to the
list unit_name_printf() resolves, as they are likely to be useful in valid unit
names too. (Note that there might be cases where this doesn't hold, but we
should still permit this, as more often than not they are safe, and if people
want to use them that way, they should be able to.)
This monopolizes unit file specifier expansion in load-fragment.c, and removes
it from socket.c + service.c. This way expansion becomes an operation done exclusively at time of loading unit files.
Previously specifiers were resolved for all settings during loading of unit
files with the exception of ExecStart= and friends which were resolved in
socket.c and service.c. With this change the latter is also moved to the
loading of unit files.
Fixes: #3061
Let's remove chase_symlinks_prefix() and instead introduce a flags parameter to
chase_symlinks(), with a flag CHASE_PREFIX_ROOT that exposes the behaviour of
chase_symlinks_prefix().
Let's use chase_symlinks() everywhere, and stop using GNU
canonicalize_file_name() everywhere. For most cases this should not change
behaviour, however increase exposure of our function to get better tested. Most
importantly in a few cases (most notably nspawn) it can take the correct root
directory into account when chasing symlinks.
We generally try to make our destructors robust regarding NULL pointers, much
in the same way as glibc's free(). Do this also for unit_free().
Follow-up for #4748.
So far systemd-nspawn container has been creating files under
/run/systemd/inaccessible, no matter whether it's running in user
namespace or not. That's fine for regular files, dirs, socks, fifos.
However, it's not for block and character devices, because kernel
doesn't allow them to be created under user namespace. It results
in warnings at booting like that:
====
Couldn't stat device /run/systemd/inaccessible/chr
Couldn't stat device /run/systemd/inaccessible/blk
====
Thus we need to have the cgroups whitelisting handler to silently ignore
a file, when the device path is prefixed with "-". That's exactly the
same convention used in directives like ReadOnlyPaths=. Also insert the
prefix "-" to inaccessible entries.
IMA validates file signatures based on the security.ima xattr. As of
Linux-4.7, instead of copying the IMA policy into the securityfs policy,
the IMA policy pathname can be written, allowing the IMA policy file
signature to be validated.
This patch modifies the existing code to first attempt to write the
pathname, but on failure falls back to copying the IMA policy contents.
We stay in the SERVICE_START while no READY=1 notification message has
been received. When we are in the SERVICE_START_POST state, we have
already received a ready notification. Hence we should not fail when the
cgroup becomes empty in that state.
Since a581e45ae8, there's a few function calls to
unit_new_for_name which will unit_free on failure. Prior to this commit,
a failure would result in calling unit_free with a NULL unit, and hit an
assertion failure, seen at least via device_setup_unit:
Assertion 'u' failed at src/core/unit.c:519, function unit_free(). Aborting.
Fixes#4747https://bugs.archlinux.org/task/51950
Before this commit, when the main process of a Type=notify service exits the
service would enter a running state without passing through the startup post
state. This meant ExecStartPost= from being executed and allowed follow-up
units to start too early (before the ready notification).
Additionally, when RemainAfterExit=yes is used on a Type=notify service, the
exit status of the main process would be disregarded.
After this commit, an unsuccessful exit of the main process of a Type=notify
service puts the unit in a failed state. A successful exit is inconsequential
in case RemainAfterExit=yes. Otherwise, when no ready notification has been
received, the unit is put in a failed state because it has never been active.
When all processes in the cgroup of a Type=notify service are gone and no ready
notification has been received yet, the unit is also put in a failed state.
Introduce a SERVICE_FAILURE_PROTOCOL error type for when a service does
not follow the protocol.
This error type is used when a pid file is expected, but not delivered.
For some reasons units remaining in the same process group as PID 1
(same_pgrp=true) fail to acquire the console even if it's not taken by anyone.
So always accept for units with same_pgrp set for now.
Zbigniew Jędrzejewski-Szmek
Lennart Poettering
Evgeny Vereshchagin
Reverend Homer
Jouke Witteveen
Thomas Hindoe Paaboel Andersen
Dave Reisner
Dongsu Park
Stefan Berger
Michael Biebl
Franck Bui