This fixes a mostly theoretical potential security hole: if for some
reason we failed to remove IPC objects created for a dynamic user (maybe
because a MAC/SElinux erronously prohibited), then we should not hand
out the same UID again until they are successfully removed.
With this commit we'll enumerate the IPC objects currently existing, and
step away from using a UID for the dynamic UID logic if there are any
matching it.
STR_IN_SET is a newer approach which is easier to write and read, and which
seems to result in space savings too:
before:
4949848 build/src/shared/libsystemd-shared-234.so
350704 build/systemctl
4967184 build/systemd
826216 build/udevadm
after:
4949848 build/src/shared/libsystemd-shared-234.so
350704 build/systemctl
4966888 build/systemd
826168 build/udevadm
If sd_bus_open_system() fail, then try to read information about
dynamic users from /run/systemd/dynamic-uid.
This makes services can successfully call getpwuid() or their friends
even if dbus.service is not started yet.
Fixes#6967.
These two sites _do_ match the definition of pid_is_valid(); they don't
provide any special handling for the invalid PID value 0. (They're used
by dbus methods, so the PID value 0 is handled with reference to the dbus
client creds, outside of these functions).
This was the one valid site in commit
ee043777be.
The second part of this hunk, avoiding using `%m`
when we didn't actually have `errno` set, seems
like a nice enough cleanup to be worthwhile on
it's own.
Also use PID_FMT to improve the error message we print
(pid_t is signed).
The configuration option was called -Dresolve, but the internal define
was …RESOLVED. This options governs more than just resolved itself, so
let's settle on the version without "d".
