userdb allows user/group records without UID/GID (it only really
requires a name), in order to permit "unfixated" records. But that means
we cannot just rely on the field to be valid. And we mostly got that
right, but not everywhere. Fix that.
When we pass information about our calling terminal on to some service
or command we invoke, propagate $COLORTERM + $NO_COLOR in addition to
$TERM, in order to always consider the triplet of the three env vars the
real deal.
This is useful when the previous invocation is unexpectedly killed.
Otherwise, if systemd-nspawn is killed forcibly, then unix-export
directory is not cleared and unmounted, and the subsequent invocation
will fail. E.g.
===
[ 18.895515] TEST-13-NSPAWN.sh[645]: + machinectl start long-running
[ 18.945703] systemd-nspawn[1387]: Mount point '/run/systemd/nspawn/unix-export/long-running' exists already, refusing.
[ 18.949236] systemd[1]: systemd-nspawn@long-running.service: Failed with result 'exit-code'.
[ 18.949743] systemd[1]: Failed to start systemd-nspawn@long-running.service.
===
Admittedly, some of our glyphs _are_ special, e.g. "O=" for SPECIAL_GLYPH_TOUCH ;)
But we don't need this in the name. The very long names make some invocations
very wordy, e.g. special_glyph(SPECIAL_GLYPH_SLIGHTLY_UNHAPPY_SMILEY).
Also, I want to add GLYPH_SPACE, which is not special at all.
It's sometimes very useful to be able to terminate a container quickly
but cleanly while talking to it. Introduce a hotkey for that: ^]^]p for
powering it off. In similar style add ^]^]r for rebooting it.
To resolve conflict with sys/mount.h and linux/mount.h or linux/fs.h.
The conflict between sys/mount.h and linux/mount.h is resolved in
glibc-2.37 (774058d72942249f71d74e7f2b639f77184160a6), but our baseline
is still glibc-2.31. Also, even with the version or newer, still
sys/mount.h conflicts with linux/fs.h, which is included by
linux/btrfs.h.
This introduces our own implementation of sys/mount.h, that can be
simultaneously included with linux/mount.h and linux/fs.h. This also
imports linux/fs.h, linux/mount.h, and several other dependent headers.
The introduced sys/mount.h header itself may not be enough simple, but
by using the header, we can drop most of workarounds in other source files.
Follow-up for 7f6af95dab
- Allocate internal buf on the stack, memdup() only at the end.
This ensures we're able to handle OOM gracefully, i.e.
return -EAGAIN on OOM while still emptying socket buffer.
- Do not treat empty notify message as error.
- Raise log level since all callers log loudly anyway.
Follow-up for 985ea98e7f.
When DevicePolicy= is enabled, but DeviceAllow= for /dev/net/tun is not
specified, bind-mounting the device node from the host system is
meaningless, as it cannot be used in the container anyway.
Let's check the device node is accessible before creating or
bind-mounting.
FUSE is userns-safe since kernel v4.18 (da315f6e03988a7127680bbc26e1028991b899b8),
and now our kernel base line is 5.4. Let's drop the logic of checking
the version of FUSE, and unconditionally enable FUSE.
This moves around the UserDBMatch handling, moves it out of userdbctl
and into generic userdb code, so that it can be passed to the server
side, to allow server side filtering.
This is preparation for one day allowing complex software to do such
filtering server side, and thus reducing the necessary traffic.
Right now no server side actually knows this, hence care is taken to
downgrade to the userdb varlink API as it was in v257 in case the new
options are not understood. This retains compatibility with any
implementation hence.
So far, we supported two modes:
1. when running unpriv we'd get the mounts from mountfsd, and the userns
from nsresourced
2. when running priv we'd do the mounts/userns ourselves
This untangles this a bit, so that we can also use mountfsd/nsresourced
when running privilged.
I think this is generally a bit nicer, and probably something we should
switch to entirely one day, as it reduces the variety of codepaths.
With this patch the default behaviour remains unchanged, but by
selecting the new "managed" option for --private-users= the codepaths
via mountfsd/nsresourced can be explicitly requested even when running
with privs.
This is mostly just reworks that we check for arg_userns_mode !=
USER_NAMESPACE_MANAGED rather than arg_privileged for a number of
codepaths, but requires more fixes, too. The devil is in the details.
This adds a new "foreign" value to --private-users-ownership= which is a
lot like "map", but maps from the host's foreign UID range rather than from the
host's 0.
(This has nothing much to do with making unprivileged directory-based
containers work, it's just very handy that we can run privileged
contains with such a mapping too, with an easy switch)
This simply calls into mountfsd to acquire the root mount and uses it as
root for the container.
Note that this also makes one more change: previously we ran containers
directory off their backing directory. Except when we didn't, and there
were a variety of exceptions: if we had no privs, if we ran off a disk
image, if the directory was the host's root dir, and some others.
This simplifies the logic a bit: we now simply always create a temporary
directory in /tmp/ and bind mount everything there, in all code paths.
This simplifies our code a bit. After all, in order to control
propagation we need to turn the root into a mount point anyway, hence we
might just do it at one place for all cases.
This is shown every time nspawn is started, which is annoying
and there's nothing a user can do about it, since it depends on
an extremely new kernel. Downgrade to debug.
Follow-up for 611ae59888
Supersedes #35308 (cherry-picked one commit and replaced the rest)
(I left a few comments that's folded by GitHub. Please make sure to
check them too.)
- Make fd_is_namespace() take NamespaceType
- Drop support for kernel without NS_GET_NSTYPE (< 4.11)
- Port is_our_namespace() to namespace_open_by_type()
(preparation for later commits, where the latter
would go by pidfd if available, avoiding procfs)
We nowadays support unprivileged invocation of systemd-nspawn +
systemd-vmspawn, but there was no support for discovering suitable disk
images (i.e. no per-user counterpart of /var/lib/machines). Add this
now, and hook it up everywhere.
Instead of hardcoding machined's, importd's, portabled's, sysupdated's
image discovery to RUNTIME_SCOPE_SYSTEM I introduced a field that make
the scope variable, even if this field is always initialized to
RUNTIME_SCOPE_SYSTEM for now. I think these four services should
eventually be updated to support a per-user concept too, this is
preparation for that, even though it doesn't outright add support for
this.
This is for the largest part not user visible, except for in nspawn,
vmspawn and the dissect tool. For the latter I added a pair of
--user/--system switches to select the discovery scope.
This function pins the *API* FS, i.e. /proc/ + /sys/, not just any fs.
Hence clarify this in the name.
(At least we call these two fs "API (V)FS" in our codebase, hence
continue to do so here)
