This reverts commit d6c9411072.
I still think this is something that needs to be done, but we're hitting some
unexplained failures, e.g. https://github.com/systemd/systemd/issues/22920.
So let's revert this for now, so -rc2 can be released, with a plan to return
to this after a release.
Closes#22920.
We would only accept "identical" links, but having e.g. a symlink
/usr/lib/systemd/system/foo-alias.service → /usr/lib/systemd/system/foo.service
when we're trying to create /usr/lib/systemd/system/foo-alias.service →
./foo.service is OK. This fixes an issue found in ubuntuautopkg package
installation, where we'd fail when enabling systemd-resolved.service, because
the existing alias was absolute, and (with the recent patches) we were trying
to create a relative one.
A test is added.
(For .wants/.requires symlinks we were already doing OK. A test is also
added, to verify.)
When we have a symlink that goes outside of our search path, we should just
ignore the target file name. But we were verifying it, and rejecting in
the case where a symlink was created manually.
The two states are distinguished, but are treated everywhere identically,
so there is no difference in behaviour except for slighlty different log
output.
We'd say that file is enabled indirectly if we had a symlink like:
foo@.service ← bar.target.wants/foo@one.service
but not when we had
foo@one.service ← bar.target.wants/foo@one.service
The effect of both link types is the same. In fact we don't care
about the symlink target. (We'll warn if it is mismatched, but we honour
it anyway.)
So let's use the original match logic only for aliases.
For .wants/.requires we instead look for a matching source name,
or a source name that matches after stripping of instance.
This is a fairly noticable change, but I think it needs to be done.
So far we'd create an absolute symlink to the target unit file:
.wants/foo.service → /usr/lib/systemd/system/foo.service
or
alias.service → /etc/systemd/system/aliased.service.
This works reasonably well, except in one case: where the unit file
is linked. When we look at a file link, the name of the physical file
isn't used, and we only take the account the symlink source name.
(In fact, the destination filename may not even be a well-formed unit name,
so we couldn't use it, even if we wanted to.) But this means that if
a file is linked, and specifies aliases, we'd create absolute links for
those aliases, and systemd would consider each "alias" to be a separate
unit. This isn't checked by the tests here, because we don't have a running
systemd instance, but it is easy enough to check manually.
The most reasonable way to fix this is to create relative links to the
unit file:
.wants/foo.service → ../foo.service
alias.service → aliased.service.
I opted to use no prefix for aliases, both normal and 'default.target',
and to add "../" for .wants/ and .requires/. Note that the link that is
created doesn't necessarily point to the file. E.g. if we're enabling
a file under /usr/lib/systemd/system, and create a symlink in /etc/systemd/system,
it'll still be "../foo.service", not "../../usr/lib/systemd/system/foo.service".
For our unit loading logic this doesn't matter, and figuring out a path
that actually leads somewhere would be more work. Since the user is allowed
to move the unit file, or add a new unit file in a different location, and
we don't actually follow the symlink, I think it's OK to create a dangling
symlink. The prefix of "../" is useful to give a hint that the link points
to files that are conceptually "one level up" in the directory hierarchy.
With the relative symlinks, systemd knows that those are aliases.
The tests are adjusted to use the new forms. There were a few tests that
weren't really testing something useful: 'test -e x' fails if 'x' is a
a dangling symlink. Absolute links in the chroot would be dangling, even
though the target existed in the expected path, but become non-dangling
when made relative and the test fails.
This should be described in NEWS, but I'm not adding that here, because
it'd likely result in conflicts.
We use the symlink source name and destination names to decide whether to remove
the symlink. But if the source name is enough to decide to remove the symlink,
we'd still look up the destination for no good reason. This is a slow operation,
let's skip it.
I linked a file as root, so I had a symlink /root/test.service ← /etc/systemd/system/test.service.
To my surpise, when running test-systemctl-enable, it failed with a cryptic EACCES.
The previous commit made the logs a bit better. Strace shows that we
were trying to follow the symlink without taking --root into account.
It seems that this bug was introduced in 66a19d85a5:
before it, we'd do readlink_malloc(), which returned a path relative to root. But
we only used that path for checking if the path is in remove_symlinks_to set, which
contains relative paths. So if the path was relative, we'd get a false-negative
answer, but we didn't go outside of the root. (We need to canonicalize the symlink
to get a consistent answer.) But after 66a19 we use chase_symlinks(), without taking
root into account which is completely bogus.
When chase_symlinks() fails, we'd get the generic error:
Failed to disable: Permission denied.
Let's at least add the failure to changes list, so the user gets
a slightly better message. Ideally, we'd say where exactly the permission
failure occured, but chase_symlinks() is a library level function and I don't
think we should add logging there. The output looks like this now:
Failed to resolve symlink "/tmp/systemctl-test.1r7Roj/etc/systemd/system/link5alias2.service": Permission denied
Failed to resolve symlink "/tmp/systemctl-test.1r7Roj/etc/systemd/system/link5alias.service": Permission denied
Failed to disable unit, file /tmp/systemctl-test.1r7Roj/etc/systemd/system/link5alias2.service: Permission denied.
Failed to disable unit, file /tmp/systemctl-test.1r7Roj/etc/systemd/system/link5alias.service: Permission denied.
We'd create aliases and other symlinks first, and only then try to create
the main link. Since that can fail, let's do things in opposite order, and
abort immediately if we can't link the file itself.
We had a check that was done in unit_file_resolve_symlink(). Let's move
the check to unit_validate_alias_symlink_or_warn(), which makes it available
to the code in install.c.
With this, unit_file_resolve_symlink() behaves almost the same. The warning
about "suspicious symlink" is done a bit later. I think this should be OK.
Some calls to lookup_path_init() were not followed by any log emission.
E.g.:
$ SYSTEMD_LOG_LEVEL=debug systemctl --root=/missing enable unit; echo $?
1
Let's add a helper function and use it in various places.
$ SYSTEMD_LOG_LEVEL=debug build/systemctl --root=/missing enable unit; echo $?
Failed to initialize unit search paths for root directory /missing: No such file or directory
1
$ SYSTEMCTL_SKIP_SYSV=1 build/systemctl --root=/missing enable unit; echo $?
Failed to initialize unit search paths for root directory /missing: No such file or directory
Failed to enable: No such file or directory.
1
The repeated error in the second case is not very nice, but this is a niche
case and I don't think it's worth the trouble to trying to avoid it.
So far we'd issue a warning (before this series, just in the logs on the server
side, and before this commit, on stderr on the caller's side), but return
success. It seems that successfull return was introduced by mistake in
aa0f357fd8 (my fault :( ), which was supposed to
be a refactoring without a functional change. I think it's better to fail,
because if enablement fails, the user will most likely want to diagnose the
issue.
Note that we still do partial enablement, as far as that is possible. So if
e.g. we have [Install] Alias=foo.service foobar, we'll create the symlink
'foo.service', but not 'foobar', since that's not a valid unit name. We'll
print info about the action taken, and about 'foobar' being invalid, and return
failure.
If an invalid arg appears in [Install] Alias=, WantedBy=, RequiredBy=,
we'd warn in the logs, but not propagate this information to the caller,
and in particular not over dbus. But if we call "systemctl enable" on a
unit, and the config if invalid, this information is quite important.
We would resolve those specifiers to the calling user/group. This is mostly OK
when done in the manager, because the manager generally operates as root
in system mode, and a non-root in user mode. It would still be wrong if
called with --test though. But in systemctl, this would be generally wrong,
since we can call 'systemctl --system' as a normal user, either for testing
or even for actual operation with '--root=…'.
When operating in --global mode, %u/%U/%g/%G should return an error.
The information whether we're operating in system mode, user mode, or global
mode is passed as the data pointer to specifier_group_name(), specifier_user_name(),
specifier_group_id(), specifier_user_id(). We can't use userdata, because
it's already used for other things.
This makes it easier to pass it around in preparation for future changes.
While at it, let's rename InstallContext c → ctx, and InstallInfo i → info.
'c' and 'i' are bad names for variables that are passed through multiple layers
of functions calls. It's easier to follow what is happening with a meaningful
variable names.
ENOENT is easily confused with the file that we're working on not being
present, e.g. when the file contains %o or something else that requires
os-release to be present. Let's use -EUNATCH instead to reduce that chances of
confusion if the context of the error is lost.
And once we have pinpointed the reason, let's provide a proper error message:
+ build/systemctl --root=/tmp/systemctl-test.TO7Mcb enable some-some-link6@.socket
/tmp/systemctl-test.TO7Mcb/etc/systemd/system/some-some-link6@.socket: Failed to resolve alias "target@A:%A.socket": Protocol driver not attached
Failed to enable unit, cannot resolve specifiers in "target@A:%A.socket".
When we are printing a valid unit name, quoting isn't necessary, because
unit names cannot contain whitespace or other confusing characters. In particular
if the unit name is prefixed by " unit " or something else that clearly
identifies the string as a unit name, quoting would just add unnecessary
noise. But when we're printing paths or invalid names, it's better to add
quotes for clarity.
We save a few lines, but the important thing is that we don't have two
different implementations with slightly different rules used for enablement
and loading. Fixes#22000.
Tested with:
- the report in #22000, it now says:
$ SYSTEMD_LOG_LEVEL=debug systemctl --root=/ enable test.service
Suspicious symlink /etc/systemd/system/test.service→/etc/systemd/system/myown.d/test.service, treating as alias.
unit_file_resolve_symlink: self-alias: /etc/systemd/system/test.service → test.service, ignoring.
running_in_chroot(): Permission denied
Suspicious symlink /etc/systemd/system/test.service→/etc/systemd/system/myown.d/test.service, treating as alias.
unit_file_resolve_symlink: self-alias: /etc/systemd/system/test.service → test.service, ignoring.
Failed to enable unit, refusing to operate on linked unit file test.service
- a symlink to /dev/null:
...
unit_file_resolve_symlink: linked unit file: /etc/systemd/system/test3.service → /dev/null
Failed to enable unit, unit /etc/systemd/system/test3.service is masked.
- the same from the host:
...
unit_file_resolve_symlink: linked unit file: /var/lib/machines/rawhide/etc/systemd/system/test3.service → /var/lib/machines/rawhide/dev/null
Failed to enable unit, unit /var/lib/machines/rawhide/etc/systemd/system/test3.service is masked.
- through the manager:
$ sudo systemctl enable test.service
Failed to enable unit: Refusing to operate on alias name or linked unit file: test.service
$ sudo systemctl enable test3.service
Failed to enable unit: Unit file /etc/systemd/system/test3.service is masked.
As seen in the first example, the warning is repeated. This is because we call
the lookup logic twice: first for sysv-compat, and then again for real. I think
that since this is only for broken setups, and when sysv-compat is enabled, and
in an infrequent manual operation, at debug level, this is OK.
Most of the codebase does this. Here we were using 'p' or 'paths'
instead. Those names are very generic and not good for a "global-like"
object like the LookupPaths instance. And we also have 'path' variable,
and it's confusing to have 'path' and 'paths' in the same function that
are unrelated.
Also pass down LookupPaths* lower in the call stack, in preparation for
future changes.
Previously the mkdir_label() family of calls was implemented in
src/shared/mkdir-label.c but its functions partly declared ins
src/shared/label.h and partly in src/basic/mkdir.h (!!). That's weird
(and wrong).
Let's clean this up, and add a proper mkdir-label.h matching the .c
file.
In general we almost never hit those asserts in production code, so users see
them very rarely, if ever. But either way, we just need something that users
can pass to the developers.
We have quite a few of those asserts, and some have fairly nice messages, but
many are like "WTF?" or "???" or "unexpected something". The error that is
printed includes the file location, and function name. In almost all functions
there's at most one assert, so the function name alone is enough to identify
the failure for a developer. So we don't get much extra from the message, and
we might just as well drop them.
Dropping them makes our code a tiny bit smaller, and most importantly, improves
development experience by making it easy to insert such an assert in the code
without thinking how to phrase the argument.
This fixes repart's, systemctl's, sysusers' and tmpfiles' specifier
expansion to honour the root dir specified with --root=. This is
relevant for specifiers such as %m, %o, … which are directly sourced
from files on disk.
This doesn't try to be overly smart: specifiers referring to runtime
concepts (i.e. boot ID, architecture, hostname) rather than files on the
medium are left as is. There's certainly a point to be made that they
should fail in case --root= is specified, but I am not entirely convinced
about that, and it's certainly something we can look into later if
there's reason to.
I wondered for a while how to hook this up best, but given that quite a
large number of specifiers resolve to data from files on disks, and most
of our tools needs this, I ultimately decided to make the root dir a
first class parameter to specifier_printf().
Replaces: #16187Fixes: #16183
When we have a unit which cannot be enabled:
# foo@.service:
...
[Install]
WantedBy=foo.target # there is no instance, so we don't know what to enable
we should throw an error when invoked directly with 'enable', but
not when doing 'preset' or 'preset-all'.
Fixes#19856.
$ systemctl enable --root=/ serial-getty@.service
Failed to enable unit, unit getty.target is a non-template unit.
↓
Failed to enable serial-getty@.service, destination unit getty.target is a non-template unit.
This had some purpose back in the day, but right now I cannot see what
difference this makes. It's hard to keep the list of all possible errors up to
date. So let's remove this, hopefully nothing breaks.
Fixes#19437.
As reported in the bug:
> # drkonqi-coredump-processor@.service
> ...
> [Install]
> WantedBy=systemd-coredump@.service
>
> The plan here is to have a systemd-coredump@ instance start the same %i for
> drkonqi-coredump-processor@. Works perfectly when creating the symlink manually
> ln -sv /usr/lib/systemd/system/drkonqi-coredump-processor@.service
> /etc/systemd/system/systemd-coredump@.service.wants/.
When DefaultInstance is set, we replace template references with
template@default-inst. But in this case we want to create a symlink for the
template name, so that systemd will fill in the instance from the
wanting/requiring unit. This is only possible for those units that actually
have an instance set, so we create the symlink only from .requires/ or .wants
of an instantiated unit (then this specific instance will be used), or a
template (than some instance will be inherited later).
Specifically:
...
[Install]
WantedBy=other@.service, fixed.service
DefaultInstance=inst
→ enable foo@.service creates other@.service.wants/foo@inst.service, and
other@a.service will want foo@inst.service, and other@b.service will want foo@inst.service,
and fixed.service will want foo@inst.service.
Without DefaultInstance,
→ enable foo@.service creates other@.service.wants/foo@.service, and
other@a.service would want foo@a.service, and other@b.service would want foo@b.service,
but enablement fails because no dependency can be created for fixed.service:
Failed to enable unit, unit fixed.service is a non-template unit.
