We should never have used an unprefixed environment variable name.
All other systemd-nspawn variables have the "SYSTEMD_NSPAWN_" prefix,
and all other systemd variables have the "SYSTEMD_" prefix.
The new variable name takes precedence, but we fall back to checking the
old one. If only the old one is found, a warning is emitted.
In addition, SYSTEMD_NSPAWN_UNIFIED_HIERARCHY="" is accepted as an override
to avoid looking for the old variable name.
We have a variable with the same name ($UNIFIED_CGROUP_HIERARCHY) in tests,
which governs both systemd-nspawn and qemu behaviour. It is not renamed.
We would parse the environment twice (to re-apply settings after reading
config from disk), but we would not check the return code first time.
This means that for some settings we would ignore invalid values, while
for others, we'd fail at some point.
Let's just consistently fail. Those environment variables define important
aspects of behaviour, and it is better for the user if we ignore invalid
values. (Unknown settings are still ignored, so forward compatibility is
maintained.)
This avoid the use of the global variable.
Also rename cgroup_unified_update() to cgroup_unified_cached() and
cgroup_unified_flush() to cgroup_unified() to better reflect their new roles.
If execve failed, we would die in safe_close(), because master was already
closed by fdset_close_others() on line 3123. IIUC, we don't need to keep the
fd open after sending it, so let's just close it immediately.
Reproducer:
sudo build/systemd-nspawn -M rawhide fooooooo
Fixup for 3acc84ebd9.
prefix_root() is equivalent to path_join() in almost all ways, hence
let's remove it.
There are subtle differences though: prefix_root() will try shorten
multiple "/" before and after the prefix. path_join() doesn't do that.
This means prefix_root() might return a string shorter than both its
inputs combined, while path_join() never does that. I like the
path_join() semantics better, hence I think dropping prefix_root() is
totally OK. In the end the strings generated by both functon should
always be identical in terms of path_equal() if not streq().
This leaves prefix_roota() in place. Ideally we'd have path_joina(), but
I don't think we can reasonably implement that as a macro. or maybe we
can? (if so, sounds like something for a later PR)
Also add in a few missing OOM checks
The OCI changes in #9762 broke a use case in which we use nspawn from
inside a container that has dropped capabilities from the bounding set
that nspawn expected to retain. In an attempt to keep OCI compliance
and support our use case, I made hard failing on setting capabilities
not in the bounding set optional (hard fail if using OCI and log only
if using nspawn cmdline).
Fixes#12539
The console tty is now allocated from within the container so it's not
necessary anymore to allocate it from the host and bind mount the pty slave
into the container. The pty master is sent to the host.
/dev/console is now a symlink pointing to the pty slave.
This might also be less confusing for applications running inside the container
and the overall result looks cleaner (we don't need to apply manually the
passed selinux context, if any, to the allocated pty for instance).
The CPU_SET_S api is pretty bad. In particular, it has a parameter for the size
of the array, but operations which take two (CPU_EQUAL_S) or even three arrays
(CPU_{AND,OR,XOR}_S) still take just one size. This means that all arrays must
be of the same size, or buffer overruns will occur. This is exactly what our
code would do, if it received an array of unexpected size over the network.
("Unexpected" here means anything different from what cpu_set_malloc() detects
as the "right" size.)
Let's rework this, and store the size in bytes of the allocated storage area.
The code will now parse any number up to 8191, independently of what the current
kernel supports. This matches the kernel maximum setting for any architecture,
to make things more portable.
Fixes#12605.
We noticed in our tests that occasionally SystemCallFilter= would
fail to set and the service would run with no syscall filtering.
Most of the time the same tests would apply the filter and fail
the service as expected. While it's not totally clear why this happens,
we noticed seccomp_load() in the systemd code base would fail open for
all errors except EPERM and EACCES.
ENOMEM, EINVAL, and EFAULT seem like reasonable values to add to the
error set based on what I gather from libseccomp code and man pages:
-ENOMEM: out of memory, failed to allocate space for a libseccomp structure, or would exceed a defined constant
-EINVAL: kernel isn't configured to support the operations, args are invalid (to seccomp_load(), seccomp(), or prctl())
-EFAULT: addresses passed as args are invalid
/tmp might not be mounted at all yet (given that we support
SYSTEMD_NSPAWN_TMPFS_TMP=0 to turn this off), and /tmp is a dir systemd
usually tries to unmount during shutdown (unlike /run), and we shouldn't
keep it busy. Hence let's just move these deleted files to /run so that
we don't keep /tmp needlessly busy.
Some chattrs only work sensible if you set them right after opening a
file for create (think: FS_NOCOW_FL). Others only work when they are
applied when the file is fully written (think: FS_IMMUTABLE_FL). Let's
take that into account when copying files and applying a chattr to them.
The function is otherwise generic enough to toggle other bind mount
flags beyond MS_RDONLY (for example: MS_NOSUID or MS_NODEV), hence let's
beef it up slightly to support that too.
Previously both run() and run_container() would free 'fds'. Let's fix
that, and let run() free it but make run_container() already remove all
fds from it, because that's what we actually want to do.
Fixes: #12073
This is a pretty large patch, and adds support for OCI runtime bundles
to nspawn. A new switch --oci-bundle= is added that takes a path to an
OCI bundle. The JSON file included therein is read similar to a .nspawn
settings files, however with a different feature set.
Implementation-wise this mostly extends the pre-existing Settings object
to carry additional properties for OCI. However, OCI supports some
concepts .nspawn files did not support yet, which this patch also adds:
1. Support for "masking" files and directories. This functionatly is now
also available via the new --inaccesible= cmdline command, and
Inaccessible= in .nspawn files.
2. Support for mounting arbitrary file systems. (not exposed through
nspawn cmdline nor .nspawn files, because probably not a good idea)
3. Ability to configure the console settings for a container. This
functionality is now also available on the nspawn cmdline in the new
--console= switch (not added to .nspawn for now, as it is something
specific to the invocation really, not a property of the container)
4. Console width/height configuration. Not exposed through
.nspawn/cmdline, but this may be controlled through $COLUMNS and
$LINES like in most other UNIX tools.
5. UID/GID configuration by raw numbers. (not exposed in .nspawn and on
the cmdline, since containers likely have different user tables, and
the existing --user= switch appears to be the better option)
6. OCI hook commands (no exposed in .nspawn/cmdline, as very specific to
OCI)
7. Creation of additional devices nodes in /dev. Most likely not a good
idea, hence not exposed in .nspawn/cmdline. There's already --bind=
to achieve the same, which is the better alternative.
8. Explicit syscall filters. This is not a good idea, due to the skewed
arch support, hence not exposed through .nspawn/cmdline.
9. Configuration of some sysctls on a whitelist. Questionnable, not
supported in .nspawn/cmdline for now.
10. Configuration of all 5 types of capabilities. Not a useful concept,
since the kernel will reduce the caps on execve() anyway. Not
exposed through .nspawn/cmdline as this is not very useful hence.
Note that this only implements the OCI runtime logic itself. It does not
provide a runc-compatible command line tool. This is left for a later
PR. Only with that in place tools such as "buildah" can use the OCI
support in nspawn as drop-in replacement.
Currently still missing is OCI hook support, but it's already parsed and
everything, and should be easy to add. Other than that it's OCI is
implemented pretty comprehensively.
There's a list of incompatibilities in the nspawn-oci.c file. In a later
PR I'd like to convert this into proper markdown and add it to the
documentation directory.
Zbigniew Jędrzejewski-Szmek
Lennart Poettering
Yu Watanabe
Anita Zhang
Franck Bui
Ben Boeckel
Dominick Grift