This is in many cases redundant, as a similar check is done by various
callers already, but in other cases (where we read the color from a
static table for example), it's nice to let the color check be done by
the table code itself, and since it doesn't hurt in the other cases just
do it again.
It's pretty useful to allow parse_boolean() to take a NULL argument and
return an error in that case, rather than abort. i.e. making this a
runtime rather than programming error allows us to shorten code
elsewhere.
it's already part of @ipc, no need to have it in both. Given that @ipc
is much more popular (as it is part of @system-service for example),
let's not define it a second time.
Let's generalize this, so that we can use this in nspawn later on, which
is pretty useful as we need to be able to mask files from the inner
child of nspawn too, where the host's /run/systemd/inaccessible
directory is not visible anymore. Moreover, if nspawn can create these
nodes on its own before the payload this means the payload can run with
fewer privileges.
Not only when we populate the "devices" cgroup controller we need
major/minor numbers, but for the io/blkio one it's the same, hence let's
use the same logic for both.
device_path_make_{major_minor|canonical) generate device node paths
given a mode_t and a dev_t. We have similar code all over the place,
let's unify this in one place. The former will generate a "/dev/char/"
or "/dev/block" path, and never go to disk. The latter then goes to disk
and resolves that path to the actual path of the device node.
device_path_parse_major_minor() reverses device_path_make_major_minor(),
also withozut going to disk.
We have similar code doing something like this at various places, let's
unify this in a single set of functions. This also allows us to teach
them special tricks, for example handling of the
/run/systemd/inaccessible/{blk|chr} device nodes, which we use for
masking device nodes, and which do not exist in /dev/char/* and
/dev/block/*
Previously we'd allow pattern expressions such as "char-input" to match
all input devices. Internally, this would look up the right major to
test in /proc/devices. With this commit the syntax is slightly extended:
- "char-*" can be used to match any kind of character device, and
similar "block-*. This expression would work previously already, but
instead of actually installing a wildcard match it would install many
individual matches for everything listed in /proc/devices.
- "char-<MAJOR>" with "<MAJOR>" being a numerical parameter works now
too. This allows clients to install whitelist items by specifying the
major directly.
The main reason to add these is to provide limited compat support for
clients that for some reason contain whitelists with major/minor numbers
(such as OCI containers).
This adds some code to hanlde /dev/block/* and /dev/char/* device node
paths specially: instead of actually stat()ing them we'll just parse the
major/minor name from the name. This is useful 'hack' to allow clients
to install whitelists for devices that don't actually have to exist.
Also, let's similarly handle /run/systemd/inaccessible/{blk|chr}. This
allows us to simplify our built-in default whitelist to not require a
"ignore_enoent" mode for these nodes.
In general we should be careful with hardcoding major/minor numbers, but
in this case this should safe.
We should probably drop path_join() entirely in the long run (and
then rename path_join_many() to it?), but for now let's make one a
wrapper for the other.
Let's be a bit more careful when parsing major/minor pairs, and filter
out more corner cases. This also means using safe_atou() rather than
sscanf() to avoid weird negative unsigned handling and such.
As it turns out glibc and the Linux kernel have different ideas about
the size of dev_t and how many bits exist for the major and the minor.
When validating major/minor numbers we should check against the kernel's
actual sizes, hence add macros for this.
Lennart Poettering