Let's add a new function that checks whether some directory is the
top-level directory inside an fs, splitting out the code for this from
verify_esp().
While we are at it, let's slightly improve the code, so that we can
correctly work if we have no priviliges but the ESP is mounted
unaccessible: if we can't stat() the path "$ESP/.." then manually remove
the last component of $ESP and check that instead. Which is very similar
in behaviour, and hopefully good enough in the unprivileged case.
udev metadata access works unprivileged, which the blkid stuff doesn't
(as that needs raw device node access). Hence let's use udev if we lack
privs, and raw device access only if root.
This 'root' field contains the root path of the partition we found the
snippet in. The 'kernel', 'initrd', 'efi', … fields are relative to this
path.
This becomes particularly useful later when we add support for loading
snippets from both the ESP and XBOOTLDR, but already simplifies the code
for us a bit in systemctl.
Previously, we'd mount the ESP to /efi if that existed and was empty,
falling back to /boot if that existed and was empty.
With this change, the XBOOTLDR partition is mounted to /boot
unconditionally. And the EFI is mounted to /efi if that exists (but it
doesn't have to be empty — after all the name is very indicative of what
this is supposed to be), and to /boot as a fallback but only if it
exists and is empty (we insist on emptiness for that, since it might be
used differently than what we assume).
The net effect is that $BOOT should be reliably found under /boot, and
the ESP is either /efi or /boot.
(Note that this commit only is relevant for nspawn and suchlike, i.e.
the codepaths that mount an image without involving udev during boot.)
The boot loader spec supports two places to store boot loader
configuration: the ESP and a generic replacement for it in case the ESP
is not available or not suitable. Let's look for both.
Run build/test in LXC for now, as full nested QEMU is too brittle right
now: https://github.com/semaphoreci/semaphore/issues/37
But this at least runs some tests. It ensures that systemd generally
works in containers, as well as provides some backup results if the main
Ubuntu CI is down.
This informs chase_symlinks that symlinks should be treated as if
the path given by --root= is the root of their file system.
With the parent commit, this allows tmpfiles to create files as the
root user under a prefix that may be owned by an unprivileged user.
In particular, this fixes the case where tmpfiles generates initial
files in a staging root directory for packaging under a directory
owned by the unprivileged packager user (e.g. in Gentoo).
When chase_symlinks is given a root path, it is assumed that all
processed symlinks are restricted under that path. It should not
be necessary to verify components of that prefix path since they
are not relevant to the symlinks.
This change skips unsafe UID transitions in this root prefix, i.e.
it now ignores when an unprivileged user's directory contains a
root-owned directory above the symlink root.
In [PR#11696][1] it came up that the formatting of continued arguments should
follow the default Emacs style. To ensure this happens when someone has changed
his setting in her private config, the value should be set by *dir-locals.el*.
[1]: https://github.com/systemd/systemd/pull/11696#pullrequestreview-205463987
Lennart Poettering
Martin Pitt
Yu Watanabe
David Michael
Zbigniew Jędrzejewski-Szmek
Ross Burton
Jörg Sommer