Let's be more careful with what we serialize: let's ensure we never
serialize strings that are longer than LONG_LINE_MAX, so that we know we
can read them back with read_line(…, LONG_LINE_MAX, …) safely.
In order to implement this all serialization functions are move to
serialize.[ch], and internally will do line size checks. We'd rather
skip a serialization line (with a loud warning) than write an overly
long line out. Of course, this is just a second level protection, after
all the data we serialize shouldn't be this long in the first place.
While we are at it also clean up logging: while serializing make sure to
always log about errors immediately. Also, (void)ify all calls we don't
expect errors in (or catch errors as part of the general
fflush_and_check() at the end.
"ExitCode" is a bit of a misnomer in two ways: it suggests this was
about the "exit code" concept that exit()/waitid() deal with, but really
isn't. Moreover, it's not event just about exiting either, but more
often about reloading/reexecing or rebooting. Let's hence pick a new
name for this that is a bit more correct.
I initially thought about naming this the "state", but that'd be a
misnomer too, as the value really encodes a "goal" more than a current
state. Also we already have the externally visible ManagerState.
No actual changes in behaviour, just the rename.
These lines are generally out-of-date, incomplete and unnecessary. With
SPDX and git repository much more accurate and fine grained information
about licensing and authorship is available, hence let's drop the
per-file copyright notice. Of course, removing copyright lines of others
is problematic, hence this commit only removes my own lines and leaves
all others untouched. It might be nicer if sooner or later those could
go away too, making git the only and accurate source of authorship
information.
This part of the copyright blurb stems from the GPL use recommendations:
https://www.gnu.org/licenses/gpl-howto.en.html
The concept appears to originate in times where version control was per
file, instead of per tree, and was a way to glue the files together.
Ultimately, we nowadays don't live in that world anymore, and this
information is entirely useless anyway, as people are very welcome to
copy these files into any projects they like, and they shouldn't have to
change bits that are part of our copyright header for that.
hence, let's just get rid of this old cruft, and shorten our codebase a
bit.
This is mostly fall-out from d1a1f0aaf0,
however some cases are older bugs.
There might be more issues lurking, this was a simple grep for "%m"
across the tree, with all lines removed that mention "errno" at all.
The function is similar to path_kill_slashes() but also removes
initial './', trailing '/.', and '/./' in the path.
When the second argument of path_simplify() is false, then it
behaves as the same as path_kill_slashes(). Hence, this also
replaces path_kill_slashes() with path_simplify().
This adds a flags parameter to unit_notify() which can be used to pass
additional notification information to the function. We the make the old
reload_failure boolean parameter one of these flags, and then add a new
flag that let's unit_notify() if we are configured to restart the
service.
Note that this adjusts behaviour of systemd to match what the docs say.
Fixes: #8398
Files which are installed as-is (any .service and other unit files, .conf
files, .policy files, etc), are left as is. My assumption is that SPDX
identifiers are not yet that well known, so it's better to retain the
extended header to avoid any doubt.
I also kept any copyright lines. We can probably remove them, but it'd nice to
obtain explicit acks from all involved authors before doing that.
This reworks the SELinux and SMACK label fixing calls in a number of
ways:
1. The two separate boolean arguments of these functions are converted
into a flags type LabelFixFlags.
2. The operations are now implemented based on O_PATH. This should
resolve TTOCTTOU races between determining the label for the file
system object and applying it, as it it allows to pin the object
while we are operating on it.
3. When changing a label fails we'll query the label previously set, and
if matches what we want to set anyway we'll suppress the error.
Also, all calls to label_fix() are now (void)ified, when we ignore the
return values.
Fixes: #8566
"check" is unclear: what is true, what is false? Let's rename to "can_gc" and
revert the return value ("positive" values are easier to grok).
v2:
- rename from unit_can_gc to unit_may_gc
It was forbidden to create mount units for a symlink. But the reason is
that the mount unit needs to know the real path that will appear in
/proc/self/mountinfo. The kernel dereferences *all* the symlinks in the
path at mount time (I checked this with `mount -c` running under `strace`).
This will have no effect on most systems. As recommended by docs, most
systems use /etc/fstab, as opposed to native mount unit files.
fstab-generator dereferences symlinks for backwards compatibility.
A relatively minor issue regarding Time Of Check / Time Of Use also exists
here. I can't see how to get rid of it entirely. If we pass an absolute
path to mount, the racing process can replace it with a symlink. If we
chdir() to the mount point and pass ".", the racing process can move the
directory. The latter might potentially be nicer, except that it breaks
WorkingDirectory=.
I'm not saying the race is relevant to security - I just want to consider
how bad the effect is. Currently, it can make the mount unit active (and
hence the job return success), despite there never being a matching entry
in /proc/self/mountinfo. This wart will be removed in the next commit;
i.e. it will make the mount unit fail instead.
It is not necessary to label as loaded to automount unit when its unit
file does not exist. So, let's make automount_load() to fail when the
unit file does not exist.
Partially fixes#7370.
This replaces the dependencies Set* objects by Hashmap* objects, where
the key is the depending Unit, and the value is a bitmask encoding why
the specific dependency was created.
The bitmask contains a number of different, defined bits, that indicate
why dependencies exist, for example whether they are created due to
explicitly configured deps in files, by udev rules or implicitly.
Note that memory usage is not increased by this change, even though we
store more information, as we manage to encode the bit mask inside the
value pointer each Hashmap entry contains.
Why this all? When we know how a dependency came to be, we can update
dependencies correctly when a configuration source changes but others
are left unaltered. Specifically:
1. We can fix UDEV_WANTS dependency generation: so far we kept adding
dependencies configured that way, but if a device lost such a
dependency we couldn't them again as there was no scheme for removing
of dependencies in place.
2. We can implement "pin-pointed" reload of unit files. If we know what
dependencies were created as result of configuration in a unit file,
then we know what to flush out when we want to reload it.
3. It's useful for debugging: "systemd-analyze dump" now shows
this information, helping substantially with understanding how
systemd's dependency tree came to be the way it came to be.
This slightly changes how we log about failures. Previously,
service_enter_dead() would log that a service unit failed along with its
result code, and unit_notify() would do this again but without the
result code. For other unit types only the latter would take effect.
This cleans this up: we keep the message in unit_notify() only for debug
purposes, and add type-specific log lines to all our unit types that can
fail, and always place them before unit_notify() is invoked.
Or in other words: the duplicate log message for service units is
removed, and all other unit types get a more useful line with the
precise result code.
This changes the mount unit state engine in the following ways:
1. The MOUNT_MOUNTING_SIGTERM and MOUNT_MOUNTING_SIGKILL are removed.
They have been pretty much equivalent to MOUNT_UNMOUNTING_SIGTERM and
MOUNT_UNMOUNTING_SIGKILL in what they do, and the outcome has been
the same as well: the unit is stopped. Hence, let's simplify things a
bit, and merge them. Note that we keep
MOUNT_REMOUNTING_{SIGTERM|SIGKILL} however, as those states have a
different outcome: the unit remains started.
2. mount_enter_signal() will now honour the SendSIGKILL= option of the
mount unit if it was set. This was previously done already when we
entered the signal states through a timeout, and was simply missing
here.
3. A new helper function mount_enter_dead_or_mounted() is added that
places the mount unit in either MOUNT_DEAD or MOUNT_MOUNTED,
depending on what the kernel thinks about the mount's state. This
function is called at various places now, wherever we finished an
operation, and want to make sure our own state reflects again what
the kernel thinks. Previously we had very similar code in a number of
places and in other places didn't recheck the kernel state. Let's do
that with the same logic and function at all relevant places now.
4. Rework mount_stop(): never forget about running control processes.
Instead: when we have a start (i.e. a /bin/mount) process running,
and are asked to stop, then enter the kill states for it, so that it
gets cleaned up. This fixes#6048. Moreover, when we have a reload
process running convert the possible states into the relevant
unmounting states, so that we can properly execute the requested
operation.
Fixes#6048
This moves pretty much all uses of getpid() over to getpid_raw(). I
didn't specifically check whether the optimization is worth it for each
replacement, but in order to keep things simple and systematic I
switched over everything at once.
When umounting an NFS filesystem, it is not safe to lstat(2) the mountpoint at
all as that can block indefinitely if the NFS server is down.
umount() will not block, but lstat() will.
This patch therefore removes the call to lstat(2) and defers the handling of
any error to the child process which will issue the umount call.
Fun fact 1 suggests that a "close()" is needed, but that close() has long since been
removed. So the comment in now meaningless and possibly confusing.
Fun fact 2 refers to a bug that has been fixed in Linux prior to v4.12
Commit: 9fa4eb8e490a ("autofs: sanity check status reported with AUTOFS_DEV_IOCTL_FAIL")
so revise the comment so that no-one goes pointlessly looking for the bug.
Since commit 36c16a7cdd ("core: rework unit timeout handling, and add
new setting RuntimeMaxSec=") TimeoutSec=0 in mount units has
cause the mount to timeout immediately instead of never as documented.
There is a similar problem with Socket.TimeoutSec and Swap.TimeoutSec.
These are easily fixed using config_parse_sec_fix_0().
Automount.TimeoutIdleSec looks like it could have the same problem,
but doesn't because the kernel treats '0' as 'no timeout'.
It handle USEC_INFINITY correctly only because that constant has
the value '-1', and when round up, it becomes zero.
To avoid possible confusion, use config_parse_sec_fix_0() as well, and
explicitly handle USEC_INFINITY.
If a process accesses an autofs filesystem while systemd is in the
middle of starting the mount unit on top of it, it is possible for the
autofs_ptype_missing_direct request from the kernel to be received after
the mount unit has been fully started:
systemd forks and execs mount ...
... access autofs, blocks
mount exits ...
systemd receives SIGCHLD ...
... kernel sends request
systemd receives request ...
systemd needs to respond to this request, otherwise the kernel will
continue to block access to the mount point.
Otherwise we'll hit an assert sooner or later.
This requires us to initialize ->where even if we come back in "masked"
mode, as otherwise we don't know how to operate on the automount and
detach it.
Fixes: #5441
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 don't have plural in the name of any other -util files and this
inconsistency trips me up every time I try to type this file name
from memory. "formats-util" is even hard to pronounce.
This adds a new invocation ID concept to the service manager. The invocation ID
identifies each runtime cycle of a unit uniquely. A new randomized 128bit ID is
generated each time a unit moves from and inactive to an activating or active
state.
The primary usecase for this concept is to connect the runtime data PID 1
maintains about a service with the offline data the journal stores about it.
Previously we'd use the unit name plus start/stop times, which however is
highly racy since the journal will generally process log data after the service
already ended.
The "invocation ID" kinda matches the "boot ID" concept of the Linux kernel,
except that it applies to an individual unit instead of the whole system.
The invocation ID is passed to the activated processes as environment variable.
It is additionally stored as extended attribute on the cgroup of the unit. The
latter is used by journald to automatically retrieve it for each log logged
message and attach it to the log entry. The environment variable is very easily
accessible, even for unprivileged services. OTOH the extended attribute is only
accessible to privileged processes (this is because cgroupfs only supports the
"trusted." xattr namespace, not "user."). The environment variable may be
altered by services, the extended attribute may not be, hence is the better
choice for the journal.
Note that reading the invocation ID off the extended attribute from journald is
racy, similar to the way reading the unit name for a logging process is.
This patch adds APIs to read the invocation ID to sd-id128:
sd_id128_get_invocation() may be used in a similar fashion to
sd_id128_get_boot().
PID1's own logging is updated to always include the invocation ID when it logs
information about a unit.
A new bus call GetUnitByInvocationID() is added that allows retrieving a bus
path to a unit by its invocation ID. The bus path is built using the invocation
ID, thus providing a path for referring to a unit that is valid only for the
current runtime cycleof it.
Outlook for the future: should the kernel eventually allow passing of cgroup
information along AF_UNIX/SOCK_DGRAM messages via a unique cgroup id, then we
can alter the invocation ID to be generated as hash from that rather than
entirely randomly. This way we can derive the invocation race-freely from the
messages.
If the corresponding mount unit is deserialized after the automount unit
then the expire event is set up in automount_trigger_notify(). However, if
the mount unit is deserialized first then the automount unit is still in
state AUTOMOUNT_DEAD and automount_trigger_notify() aborts without setting
up the expire event.
Explicitly call automount_start_expire() during coldplug to make sure that
the expire event is set up as necessary.
Fixes#4249.
Previously, the result value of a unit was overriden with each failure that
took place, so that the result always reported the last failure that took
place.
With this commit this is changed, so that the first failure taking place is
stored instead. This should normally not matter much as multiple failures are
sufficiently uncommon. However, it improves one behaviour: if we send SIGABRT
to a service due to a watchdog timeout, then this currently would be reported
as "coredump" failure, rather than the "watchodg" failure it really is. Hence,
in order to report information about the type of the failure, and not about
the effect of it, let's change this from all unit type to store the first, not
the last failure.
This addresses the issue pointed out here:
https://github.com/systemd/systemd/pull/3818#discussion_r73433520
All pending tokens are already serialized correctly and will be handled
when the mount unit is done.
Without this a 'daemon-reload' cancels all pending tokens. Any process
waiting for the mount will continue with EHOSTDOWN.
This can happen when the mount unit waits for it's dependencies, e.g.
network, devices, fsck, etc.
This basically reverts 7b2fd9d512 ("core:
remove duplicate code in automount_update_mount()").
This was not duplicate code. The expire_tokens need to be handled as well:
Send 0 == success for MOUNT_DEAD (umount successful), do nothing for
MOUNT_UNMOUNTING (not yet done) and an error for everything else.
Otherwise the automount logic will assume unmounting is not done and will
not send any new requests for mounting. As a result, the corresponding
mount unit is never mounted.
Without this, automounts with TimeoutIdleSec= are broken. Once the idle
timeout triggered a umount, any access to the corresponding filesystem
hangs forever.
Fixes#3332.
Port the progagation logic to the generic Unit->trigger_notify() callback logic
in the unit vtable, that is called for a unit not only when the triggered unit
of it changes state but also when a job for that unit finishes. This, firstly
allows us to make the code a bit cleaner and more generic, but more
importantly, allows us to notice correctly when a mount job fails, and
propagate that back to autofs client processes.
Fixes: #2181
Let's move the enforcement of the per-unit start limit from unit.c into the
type-specific files again. For unit types that know a concept of "result" codes
this allows us to hook up the start limit condition to it with an explicit
result code. Also, this makes sure that the state checks in clal like
service_start() may be done before the start limit is checked, as the start
limit really should be checked last, right before everything has been verified
to be in order.
The generic start limit logic is left in unit.c, but the invocation of it is
moved into the per-type files, in the various xyz_start() functions, so that
they may place the check at the right location.
Note that this change drops the enforcement entirely from device, slice, target
and scope units, since these unit types generally may not fail activation, or
may only be activated a single time. This is also documented now.
Note that restores the "start-limit-hit" result code that existed before
6bf0f408e4 already in the service code. However,
it's not introduced for all units that have a result code concept.
Fixes#3166.