On the local bus SO_PEERCRED says who is calling and the kernel is the
one saying it. Behind a broker one connection carries every caller,
so that credential describes dbus-daemon and nothing else, and every
privileged method was refused there, root included.
Ask the bus driver instead. libink parks the call and hands us the
sender; we ask GetConnectionUnixUser and answer when the reply lands,
through the same event loop as everything else. Nothing blocks:
blocking in PID 1 is why libuEv exists. That needs calls libink can
make on a connection it already has, so it gained those too.
Answers are cached, since a bus never reuses a unique name while it
runs. Not across a restart though: a new dbus-daemon numbers from
scratch and :1.7 becomes somebody else, so the cache goes when the
broker does. A sender name too long to key on is refused rather than
truncated, two callers sharing a truncated key would share an
identity.
Privilege is no longer uid 0 alone. The socket is already owned by
the --with-group group, so refusing its members every method that
changes anything left a wheel user able to open the bus and unable to
reboot. Both gates now say the same thing.
Group membership needs NSS, which the C library loads with dlopen(),
so the lookup is compiled out where Finit is built to link statically.
That leaves such a build root-only, which is worth saying out loud
rather than leaving to be discovered.
Signed-off-by: Joachim Wiberg <troglobit@gmail.com>
Finit now requires being able to query at least for the root user and
group before starting any services.
Also, add support for using libraries installed in /usr/local
Signed-off-by: Joachim Wiberg <troglobit@gmail.com>
This patch extens the SysV compatibility support in Finit by adding
support for limiting `runparts` to run only SNNfoo, or KNNfoo, style
scripts from a directory.
Additionally, by default `runparts` now runs entirely in the background
without any progress. To enable progress, an optional argument has been
added to the runparts command line.
Signed-off-by: Joachim Wiberg <troglobit@gmail.com>
Multiple parallel tests writing to the same /var leads to quite
unexpected results. Let's start fresh in each test instead.
Signed-off-by: Joachim Wiberg <troglobit@gmail.com>
This was a tough nut to crack. Spent 3-4 calendar weeks (getting blurry
now) to try and figure it all out. In the end, the following changes
were necessary:
- Ensure setup-root.sh is guaranteed to run before any of the tests
- Give all tests their unique /etc, /tmp, and /run inside the chroot.
Turns out tmpfs+overlayfs can be used unprivileged inside an unshare
- A static BusyBox binary with support for mount helpers so we can
do the mkdir magic in skel/etc/fstab for the /etc overlay
The last item turned out to be a bit of a roller coaster ride of its
own. First of all, the original binary we used was from the upstream
BusyBox project[1]. I was sure it couldn't be that hard to enable the
CONFIG_FEATURE_MOUNT_HELPERS ... oh boy was I wrong. To make long and
tedious story short; two new projects on GitHub were created for this
task: 1) troglobit/misc[2] to house a mirror of https://musl.cc
toolchains and 2) troglobit/busybox-builder[3] to download, patch, and
build the thing using a .config from the myLinux[4] project. Patching
this .config was necessary, however, since musl libc is strict POSIX
and does not have any of the BSD extensions, e.g. REG_STARTEND that is
in GLIBC regex(3).
[1]: https://busybox.net/downloads/binaries/1.31.0-defconfig-multiarch-musl/
[2]: https://github.com/troglobit/misc/releases/tag/11-20211120
[3]: https://github.com/troglobit/busybox-builder/releases/tag/1_35_0
[4]: https://github.com/troglobit/myLinux
Signed-off-by: Joachim Wiberg <troglobit@gmail.com>
Instead of having to create files, and copying them in place for each
test, we move all static test files to a skeleton rootfs. This makes
it a lot easier to get an overview of how things and how they work.
Signed-off-by: Joachim Wiberg <troglobit@gmail.com>
Joachim Wiberg