This suppresses the following warning
```
execute.c:2149:12: warning: ‘setup_smack’ defined but not used [-Wunused-function]
static int setup_smack(
^~~~~~~~~~~
```
This makes sure we migrate /var/lib/<foo> if it exists to
/var/lib/private/<foo> if DynamicUser=1 is set. This is useful to allow
turning on DynamicUser= on services that previously didn't use it, and
we can deal with this, and migrate the relevant directories as
necessary.
Note that "downgrading" from DynamicUser=1 backto DynamicUser=0 works
too. However in that case we simply continue to use
/var/lib/private/<foo>, which works because /var/lib/<foo> is a symlink
there after all.
We never use these functions seperately, hence don't bother splitting
them into to.
Also, simplify things a bit, and maintain tables for the attribute files
to chown. Let's also update those tables a bit, and include thenew
"cgroup.threads" file in it, that needs to be delegated too, according
to the documentation.
Smack LSM needs the capability CAP_MAC_ADMIN to allow
setting of the current Smack exec label. Consequently,
dropping capabilities must be done after changing the
current exec label.
This is only related to Smack LSM. But for clarity and
regularity, all setting of security context moved before
dropping capabilities.
See Issue 7108
These new settings permit specifiying arbitrary paths as
stdin/stdout/stderr locations. We try to open/create them as necessary.
Some special magic is applied:
1) if the same path is specified for both input and output/stderr, we'll
open it only once O_RDWR, and duplicate them fd instead.
2) If we an AF_UNIX socket path is specified, we'll connect() to it,
rather than open() it. This allows invoking systemd services with
stdin/stdout/stderr connected to arbitrary foreign service sockets.
Fixes: #3991
property_get_output_fdname() already had two different control flows for
stdout and stderr, it might as well handle stdin too, thus shortening
our code a bit.
Both permit configuring data to pass through STDIN to an invoked
process. StandardInputText= accepts a line of text (possibly with
embedded C-style escapes as well as unit specifiers), which is appended
to the buffer to pass as stdin, followed by a single newline.
StandardInputData= is similar, but accepts arbitrary base64 encoded
data, and will not resolve specifiers or C-style escapes, nor append
newlines.
This may be used to pass input/configuration data to services, directly
in-line from unit files, either in a cooked or in a more raw format.
Given that Linux assigns the same ioctl numbers ot multiple subsystems,
we should be careful when invoking ioctls, so that we don't end up
calling something we wouldn't want to call.
We are using the same pattern at various places: call dup2() on an fd,
and close the old fd, usually in combination with some O_CLOEXEC
fiddling. Let's add a little helper for this, and port a few obvious
cases over.
And let's make use of it to implement two new unit settings with it:
1. LogLevelMax= is a new per-unit setting that may be used to configure
log priority filtering: set it to LogLevelMax=notice and only
messages of level "notice" and lower (i.e. more important) will be
processed, all others are dropped.
2. LogExtraFields= is a new per-unit setting for configuring per-unit
journal fields, that are implicitly included in every log record
generated by the unit's processes. It takes field/value pairs in the
form of FOO=BAR.
Also, related to this, one exisiting unit setting is ported to this new
facility:
3. The invocation ID is now pulled from /run/systemd/units/ instead of
cgroupfs xattrs. This substantially relaxes requirements of systemd
on the kernel version and the privileges it runs with (specifically,
cgroupfs xattrs are not available in containers, since they are
stored in kernel memory, and hence are unsafe to permit to lesser
privileged code).
/run/systemd/units/ is a new directory, which contains a number of files
and symlinks encoding the above information. PID 1 creates and manages
these files, and journald reads them from there.
Note that this is supposed to be a direct path between PID 1 and the
journal only, due to the special runtime environment the journal runs
in. Normally, today we shouldn't introduce new interfaces that (mis-)use
a file system as IPC framework, and instead just an IPC system, but this
is very hard to do between the journal and PID 1, as long as the IPC
system is a subject PID 1 manages, and itself a client to the journal.
This patch cleans up a couple of types used in journal code:
specifically we switch to size_t for a couple of memory-sizing values,
as size_t is the right choice for everything that is memory.
Fixes: #4089Fixes: #3041Fixes: #4441
This makes each system call in SystemCallFilter= blacklist optionally
takes errno name or number after a colon. The errno takes precedence
over the one given by SystemCallErrorNumber=.
C.f. #7173.
Closes#7169.
RuntimeDirectory= often used for sharing files or sockets with other
services. So, if creating them under private/ sub-directory, we cannot
set DynamicUser= to service units which want to share something through
RuntimeDirectory=.
This makes the directories given by RuntimeDirectory= are created under
/run/ even if DynamicUser= is set.
Fixes#7260.
The error message corresponds to EILSEQ is "Invalid or incomplete
multibyte or wide character", and is not suitable in this case.
So, let's show a custom error message when the function
dynamic_creds_realize() returns -EILSEQ.
We generally use the casing "Namespace" for the word, and that's visible
in a number of user-facing interfaces, including "RestrictNamespace=" or
"JoinsNamespaceOf=". Let's make sure to use the same casing internally
too.
As discussed in #7024
The advantage is that is the name is mispellt, cpp will warn us.
$ git grep -Ee "conf.set\('(HAVE|ENABLE)_" -l|xargs sed -r -i "s/conf.set\('(HAVE|ENABLE)_/conf.set10('\1_/"
$ git grep -Ee '#ifn?def (HAVE|ENABLE)' -l|xargs sed -r -i 's/#ifdef (HAVE|ENABLE)/#if \1/; s/#ifndef (HAVE|ENABLE)/#if ! \1/;'
$ git grep -Ee 'if.*defined\(HAVE' -l|xargs sed -i -r 's/defined\((HAVE_[A-Z0-9_]*)\)/\1/g'
$ git grep -Ee 'if.*defined\(ENABLE' -l|xargs sed -i -r 's/defined\((ENABLE_[A-Z0-9_]*)\)/\1/g'
+ manual changes to meson.build
squash! build-sys: use #if Y instead of #ifdef Y everywhere
v2:
- fix incorrect setting of HAVE_LIBIDN2
Let's optimize dynamic UID allocation a bit: if a StateDirectory= (or
suchlike) is configured, we start our allocation loop from that UID and
use it if it currently isn't used otherwise. This is beneficial as it
saves us from having to expensively recursively chown() these
directories in the typical case (which StateDirectory= does when it
notices that the owner of the directory doesn't match the UID picked).
With this in place we now have the a three-phase logic for allocating a
dynamic UID:
a) first, we try to use the owning UID of StateDirectory=,
CacheDirectory=, LogDirectory= if that exists and is currently
otherwise unused.
b) if that didn't work out, we hash the UID from the service name
c) if that didn't yield an unused UID either, randomly pick new ones
until we find a free one.
Let's clean up the interaction of StateDirectory= (and friends) to
DynamicUser=1: instead of creating these directories directly below
/var/lib, place them in /var/lib/private instead if DynamicUser=1 is
set, making that directory 0700 and owned by root:root. This way, if a
dynamic UID is later reused, access to the old run's state directory is
prohibited for that user. Then, use file system namespacing inside the
service to make /var/lib/private a readable tmpfs, hiding all state
directories that are not listed in StateDirectory=, and making access to
the actual state directory possible. Mount all directories listed in
StateDirectory= to the same places inside the service (which means
they'll now be mounted into the tmpfs instance). Finally, add a symlink
from the state directory name in /var/lib/ to the one in
/var/lib/private, so that both the host and the service can access the
path under the same location.
Here's an example: let's say a service runs with StateDirectory=foo.
When DynamicUser=0 is set, it will get the following setup, and no
difference between what the unit and what the host sees:
/var/lib/foo (created as directory)
Now, if DynamicUser=1 is set, we'll instead get this on the host:
/var/lib/private (created as directory with mode 0700, root:root)
/var/lib/private/foo (created as directory)
/var/lib/foo → private/foo (created as symlink)
And from inside the unit:
/var/lib/private (a tmpfs mount with mode 0755, root:root)
/var/lib/private/foo (bind mounted from the host)
/var/lib/foo → private/foo (the same symlink as above)
This takes inspiration from how container trees are protected below
/var/lib/machines: they generally reuse UIDs/GIDs of the host, but
because /var/lib/machines itself is set to 0700 host users cannot access
files in the container tree even if the UIDs/GIDs are reused. However,
for this commit we add one further trick: inside and outside of the unit
/var/lib/private is a different thing: outside it is a plain,
inaccessible directory, and inside it is a world-readable tmpfs mount
with only the whitelisted subdirs below it, bind mounte din. This
means, from the outside the dir acts as an access barrier, but from the
inside it does not. And the symlink created in /var/lib/foo itself
points across the barrier in both cases, so that root and the unit's
user always have access to these dirs without knowing the details of
this mounting magic.
This logic resolves a major shortcoming of DynamicUser=1 units:
previously they couldn't safely store persistant data. With this change
they can have their own private state, log and data directories, which
they can write to, but which are protected from UID recycling.
With this change, if RootDirectory= or RootImage= are used it is ensured
that the specified state/log/cache directories are always mounted in
from the host. This change of semantics I think is much preferable since
this means the root directory/image logic can be used easily for
read-only resource bundling (as all writable data resides outside of the
image). Note that this is a change of behaviour, but given that we
haven't released any systemd version with StateDirectory= and friends
implemented this should be a safe change to make (in particular as
previously it wasn't clear what would actually happen when used in
combination). Moreover, by making this change we can later add a "+"
modifier to these setings too working similar to the same modifier in
ReadOnlyPaths= and friends, making specified paths relative to the
container itself.
In most cases we followed the rule that the special _INVALID and _MAX
values we use in our enums use the full type name as prefix (in contrast
to regular values that we often make shorter), do so for
ExecDirectoryType as well.
No functional changes, just a little bit of renaming to make this code
more like the rest.
This is particularly useful when used in conjunction with DynamicUser=1,
where the UID might change for every invocation, but is useful in other
cases too, for example, when these directories are shared between
systems where the UID assignments differ slightly.
Just in case something opened them, let's make sure glibc invalidates
them too.
Thankfully so far no library opened log channels behind our back, at
least as far as I know, hence this is actually a NOP, but let's better
be safe than sorry.
Now that logging can implicitly reopen the log streams when needed we
can log errors without any special magic, hence let's normalize things,
and log the same way we do everywhere else.
This adds IOVEC_INIT() and IOVEC_MAKE() for initializing iovec structures
from a pointer and a size. On top of these IOVEC_INIT_STRING() and
IOVEC_MAKE_STRING() are added which take a string and automatically
determine the size of the string using strlen().
This patch removes the old IOVEC_SET_STRING() macro, given that
IOVEC_MAKE_STRING() is now useful for similar purposes. Note that the
old IOVEC_SET_STRING() invocations were two characters shorter than the
new ones using IOVEC_MAKE_STRING(), but I think the new syntax is more
readable and more generic as it simply resolves to a C99 literal
structure initialization. Moreover, we can use very similar syntax now
for initializing strings and pointer+size iovec entries. We canalso use
the new macros to initialize function parameters on-the-fly or array
definitions. And given that we shouldn't have so many ways to do the
same stuff, let's just settle on the new macros.
(This also converts some code to use _cleanup_ where dynamically
allocated strings were using IOVEC_SET_STRING() before, to modernize
things a bit)
