This introduces PinnedResources as a structure combining pinned
references to a root directory, root image, or root mstack. This is not
only easier to work with, but essential to make certain unpriv things
work, as we need some mechanism to pin resources before we drop into a
userns which might possibly not provide access anymore to those
resources.
Hence this does two things: introduce the new structure, and immediately
hook it up so that we pin things properly before dropping into userns,
and then makes use of this after dropping the right way, and enables
unpriv userns operation.
The concept is generic enough to eventually implement extension images +
mount images with the same structure, but in order to keep the changes
managable this is left for another time.
(This also makes one further clean-up: client-side verity-reuse checks
are moved server side if we are unpriv. Previously we'd do them client
side, but they were doomed to fail because of lack of privs. Hence let's
drop the client side if we are unpriv and purely do them server-side in
that case.)
sys/prctl.h anyway includes linux/prctl.h and actually these .c files
includes sys/prctl.h. Hence, it is not necessary to explicitly include
linux/prctl.h.
RootDirectory= but via a open_tree() file descriptor. This allows
setting up the execution environment for a service by the client in
a mount namespace and then starting a transient unit in that execution
environment using the new property.
We also add --root-directory= and --same-root-dir= to systemd-run to
have it run services within the given root directory. As systemd-run
might be invoked from a different mount namespace than what systemd is
running in, systemd-run opens the given path with open_tree() and then
sends it to systemd using the new RootDirectoryFileDescriptor= property.
Child processes are left hanging on abort() as these child procs
freeze(), so test suites hang as well when test-namespace fails,
and processes are leaked.
From the docs:
The parent-death signal setting is also cleared upon changes to any of
the following thread credentials: effective user ID, effective group ID,
filesystem user ID, or filesystem group ID.
Set the deathsig again after changing id.
Follow-up for 2ade821859
It is killed when the main test process exists, but still,
it will be left hanging while other test cases run, so it's
not very clean.
Follow-up for 8b5e3be88e
Otherwise the child processes will continue, return to the test
main function, and try to run other test cases themselves:
<...>
/* test_namespace_get_leader */
PID hierarchy: 553438 ← 553459 ← 553460
/* test_detach_mount_namespace_harder */
/* test_detach_mount_namespace_harder */
/* test_detach_mount_namespace_harder */
Follow-up for 0b8b13324e
We use symbols provided by unistd.h without including it. E.g.
open(), close(), read(), write(), access(), symlink(), unlink(), rmdir(),
fsync(), syncfs(), lseek(), ftruncate(), fchown(), dup2(), pipe2(),
getuid(), getgid(), gettid(), getppid(), pipe2(), execv(), _exit(),
environ, STDIN_FILENO, STDOUT_FILENO, STDERR_FILENO, F_OK, and their
friends and variants, so on.
Currently, unistd.h is indirectly included mainly in the following two paths:
- through missing_syscall.h, which is planned to covert to .c file.
- through signal.h -> bits/sigstksz.h, which is new since glibc-2.34.
Note, signal.h is included by sd-eevent.h. So, many source files
indirectly include unistd.h if newer glibc is used.
Currently, our baseline on glibc is 2.31. We need to support glibc older
than 2.34, but unfortunately, we do not have any CI environments with
such old glibc. CIFuzz uses glibc-2.31, but it builds only fuzzers, and
many files are even not compiled.
To make sure everything still compiles, we add a preliminary include
of forward.h to tests.h to make sure it is included in every test source
file. We'll clean up the tests.h includes in a later commit.
We also add a <errno.h> include to errno-list.h to keep test-errno-list.c
compiling. It'll be removed again when we clean up includes in src/basic.
Split out of #37344.
Unprivileged namespaces are only allowed if the "setgroups" file is set
to "deny" for processes. And we need to write it before writing the
gidmap. Hence add a parameter for that.
Then, also patch all current users to actually enable this. The usecase
generally don't need it (because they don't care about unprivileged
userns), but it doesn't hurt to enable the concept anyway in all current
users (none of them actually runs complex userspace in them, but they
mostly use userns_acquire() for idmapped mounts and similar).
Let's anyway make this option explicit in the function call, to indicate
that the concept exists and is applied.
This makes sure the the codepath that derives an nsfd from a pid works
the same for the pidfd case and the non-pidfd case: if we can verify
that /proc/ is mounted but the /proc/$PID/ns/ files are missing, we can
assume the ns type is not supported by the kernel. Hence return the same
ENOPKG error in this case as we already do in the pidfd ioctl based
codepath.
- 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)
When running in LXC with AppArmor we'll most likely get an error when creating
a network namespace due to a kernel regression in < v6.2 affecting AppArmor,
resulting in denials. Like other tests, avoid failing in case of permission
issues and handle it gracefully.
We use it for more than just pipe() arrays. For example also for
socketpair(). Hence let's give it a generic name.
Also add EBADF_TRIPLET to mirror this for things like
stdin/stdout/stderr arrays, which we use a bunch of times.
When we're starting early boot services such as systemd-userdbd.service,
/tmp might not yet be mounted, so let's use a directory in /run instead
which is guaranteed to be available.
This reverts commits
- 9ae3624889
"test-execute: add tests for credentials directory with mount namespace"↲
- 94fe4cf255
"core: do not leak mount for credentials directory if mount namespace is enabled",
- 7241b9cd72
"core/credential: make setup_credentials() return path to credentials directory",
- fbaf3b23ae
"core: set $CREDENTIALS_DIRECTORY only when we set up credentials"
Before the commits, credentials directory set up on ExecStart= was kept
on e.g. ExecStop=. But, with the changes, if a service requests a
private mount namespace, the credentials directory is discarded after
ExecStart= is finished.
Let's revert the change, and find better way later.
Addresses the post-merge comment
https://github.com/systemd/systemd/pull/28787#issuecomment-1690614202.
Since kernel v5.2, open_tree() and move_mount() are added. If a service
loads or sets credentials, then let's try to clone the mount that contains
credentials with open_tree(), then mount it after a (private) mount
namespace is initialized for the service. Then, we can setup a mount for
credentials directory without leaking it to the main shared mount
namespace.
With this change, the credentials for services that request their own
private mount namespace become much much safer. And, the number of mount
events triggered by setting up credential directories can be decreased.
Unfortunately, this does not 'fix' the original issue #25527, as the
reported service does not requests private mount namespace, but the
situation should be better now.
Currently for portable services we automatically add a bind mount
os-release -> /run/host/os-release. This becomes problematic for the
soft-reboot case, as it's likely that portable services will be configured
to survive it, and thus would forever keep a reference to the old host's
os-release, which would be a problem because it becomes outdated, and also
it stops the old rootfs from being garbage collected.
Create a copy when the manager starts under /run/systemd/propagate instead,
and bind mount that for all services using RootDirectory=/RootImage=, so
that on soft-reboot the content gets updated (without creating a new file,
so the existing bind mounts will see the new content too).
This expands the /run/host/os-release protocol to more services, but I
think that's a nice thing to have too.
Closes https://github.com/systemd/systemd/issues/28023
Let's reduce the argument count of setup_namespace() a bit by loading
the sidecar verity settings in apply_mount_namespace(). This will also
make it possible to pass file descriptors to the root image/directory
into setup_namespace() as before this wasn't possible because the
verity settings logic looks for sidecar files next to the
root image which requires the path to be available.
-1 was used everywhere, but -EBADF or -EBADFD started being used in various
places. Let's make things consistent in the new style.
Note that there are two candidates:
EBADF 9 Bad file descriptor
EBADFD 77 File descriptor in bad state
Since we're initializating the fd, we're just assigning a value that means
"no fd yet", so it's just a bad file descriptor, and the first errno fits
better. If instead we had a valid file descriptor that became invalid because
of some operation or state change, the other errno would fit better.
In some places, initialization is dropped if unnecessary.
Unprivileged overlayfs is supported since Linux 5.11. The only
change needed to get ExtensionDirectories to work is to avoid
hard-coding the staging directory to the system manager runtime
directory, everything else just works (TM).
C macros are nasty. We use them, but we try to be conservative with
them. In particular passing literal, complex code blocks as argument is
icky, because of "," handling of C, and also because it's quite a
challange for most code highlighters and similar. Hence, let's avoid
that. Using macros for genreating functions is OK but if so, the
parameters should be simple words, not full code blocks.
hence, rework DEFINE_CUSTOM_TEST_MAIN() to take a function name instead
of code block as argument.
As side-effect this also fixes a bunch of cases where we might end up
returning a negative value from main().
Some uses of DEFINE_CUSTOM_TEST_MAIN() inserted local variables into the
main() functions, these are replaced by static variables, and their
destructors by the static destructor logic.
This doesn't fix any bugs or so, it's just supposed to make the code
easier to work with and improve it easthetically.
Or in other words: let's use macros where it really makes sense, but
let's not go overboard with it.
(And yes, FOREACH_DIRENT() is another one of those macros that take
code, and I dislike that too and regret I ever added that.)
Add a new setting that follows the same principle and implementation
as ExtensionImages, but using directories as sources.
It will be used to implement support for extending portable images
with directories, since portable services can already use a directory
as root.
The /var/lib/private/foo -> /var/lib/foo symlink for StateDirectory and
DynamicUser is set up on the host filesystem, before the mount namespacing
is brought up. If an empty /var/lib is used, to ensure the service does not
see other services data, the symlink is then not available despite
/var/lib/private being set up as expected.
Make a list of symlinks that need to be set up, and create them after all
the namespaced filesystems have been created, but before any eventual
read-only switch is flipped.
Mike Yuan
Lennart Poettering
Daan De Meyer
Yu Watanabe
Luca Boccassi
Michal Sekletar
Lennart Poettering
Andres Beltran
Luca Boccassi
Zbigniew Jędrzejewski-Szmek
Luca Boccassi
Jan Janssen