We have four legal cases:
1. /usr/lib/os-release exists and /etc/os-release is a symlink to it
2. both exist but /etc/os-release is not a symlink to /usr/lib/os-release
3. only /usr/lib/os-release exists
4. only /etc/os-release exists
The generic setup code in test-functions and create-busybox-image didn't handle
case 3.
The test-specific code in TEST-50 didn't handle 2 (because the general setup
code would only install /etc/os-release in the image and
grep -f /usr/lib/os-release would not work) and 4 (same reason) and would fail
in case 3 in generic setup.
Follow the same model established for RootImage and RootImageOptions,
and allow to either append a single list of options or tuples of
partition_number:options.
Follows the same pattern and features as RootImage, but allows an
arbitrary mount point under / to be specified by the user, and
multiple values - like BindPaths.
Original implementation by @topimiettinen at:
https://github.com/systemd/systemd/pull/14451
Reworked to use dissect's logic instead of bare libmount() calls
and other review comments.
Thanks Topi for the initial work to come up with and implement
this useful feature.
Allows to specify mount options for RootImage.
In case of multi-partition images, the partition number can be prefixed
followed by colon. Eg:
RootImageOptions=1:ro,dev 2:nosuid nodev
In absence of a partition number, 0 is assumed.
Opening a verity device is an expensive operation. The kernelspace operations
are mostly sequential with a global lock held regardless of which device
is being opened. In userspace jumps in and out of multiple libraries are
required. When signatures are used, there's the additional cryptographic
checks.
We know when two devices are identical: they have the same root hash.
If libcrypsetup returns EEXIST, double check that the hashes are really
the same, and that either both or none have a signature, and if everything
matches simply remount the already open device. The kernel will do
reference counting for us.
In order to quickly and reliably discover if a device is already open,
change the node naming scheme from '/dev/mapper/major:minor-verity' to
'/dev/mapper/$roothash-verity'.
Unfortunately libdevmapper is not 100% reliable, so in some case it
will say that the device already exists and it is active, but in
reality it is not usable. Fallback to an individually-activated
unique device name in those cases for robustness.
dm-verity support in dissect-image at the moment is restricted to GPT
volumes.
If the image a single-filesystem type without a partition table (eg: squashfs)
and a roothash/verity file are passed, set the verity flag and mark as
read-only.
