This is a safey net anyway, let's make it fully safe: if the data ends
on an uneven byte, then we need to complete the UTF-16 codepoint first,
before adding the final NUL byte pair. Hence let's suffix with three
NULs, instead of just two.
Tracking down #15931 confused the hell out of me, since running homed in
gdb from the command line worked fine, but doing so as a service failed.
Let's make this more debuggable and check if we live in the host netns
when allocating a new udev monitor.
This is just debug stuff, so that if things don't work, a quick debug
run will reveal what is going on.
That said, while we are at it, also fix unexpected closing of passed in
fd when failing.
Let's be more thorough that whenever we build a unit name based on
parameters, that the result is actually a valid user name. If it isn't
fail early.
This should allows us to catch various issues earlier, in particular
when we synthesize mount units from /proc/self/mountinfo: instead of
actually attempting to allocate a mount unit we will fail much earlier
when we build the name to synthesize the unit under. Failing early is a
good thing generally.
And do not use it in the IMPORT{cmdline} udev code. Wherever we expose
direct interfaces to check the kernel cmdline, let's not consult our
systemd-specific EFI variable, but strictly use the actual kernel
variable, because that's what we claim we do. i.e. it's fine to use the
EFI variable for our own settings, but for the generic APIs to the
kernel cmdline we should not use it.
Specifically, this applies to IMPORT{cmdline} and
ConditionKernelCommandLine=. In the latter case we weren#t checking the
EFI variable anyway, hence let's do the same for the udev case, too.
Fixes: #15739
It annoyed me for quite a while that running "journalctl --file=…" on a
file that is not readable failed with a "File not found" error instead
of a permission error. Let's fix that.
We make this work by using the GLOB_NOCHECK flag for glob() which means
that files are not accessible will be returned in the array as they are
instead of being filtered away. This then means that our later attemps
to open the files will fail cleanly with a good error message.
kernel 5.6 added support for a new flag for getrandom(): GRND_INSECURE.
If we set it we can get some random data out of the kernel random pool,
even if it is not yet initializated. This is great for us to initialize
hash table seeds and such, where it is OK if they are crap initially. We
used RDRAND for these cases so far, but RDRAND is only available on
newer CPUs and some archs. Let's now use GRND_INSECURE for these cases
as well, which means we won't needlessly delay boot anymore even on
archs/CPUs that do not have RDRAND.
Of course we never set this flag when generating crypto keys or uuids.
Which makes it different from RDRAND for us (and is the reason I think
we should keep explicit RDRAND support in): RDRAND we don't trust enough
for crypto keys. But we do trust it enough for UUIDs.