When nested mounts appear under a sysext hierarchy like this:
mkdir -p /opt/trigger/
mount -t tmpfs tmpfs /opt/trigger
mkdir -p /opt/trigger/inner
mount -t tmpfs tmpfs /opt/trigger/inner
Then systemd-sysext merge will lose the inner mount because it uses a
regular bind mount with propagation and then unmounts the source,
unmounting all children with it which propagates (as found out in
https://github.com/flatcar/Flatcar/issues/2111).
To solve this, clone the sub mount with MS_PRIVATE to decouple sub
mounts from the original mount. Then attach the cloned mount instead of
doing regular bind mounts. For old kernels we still attach the cloned
mount but we fallback to cloning without MS_PRIVATE. This change also
affects mount_private_apivfs which is used for private /proc, /sys, and
cgroupfs but I think it makes sense there, too, instead of only doing
mount_setattr for sysext alone because, e.g., a container and the host
should not be leaking mount actions into each other for these mounts.
When nested mounts appear under a sysext hierarchy like this:
mkdir -p /opt/trigger/
mount -t tmpfs tmpfs /opt/trigger
mkdir -p /opt/trigger/inner
mount -t tmpfs tmpfs /opt/trigger/inner
Then systemd-sysext merge hit an assertion reported in
https://github.com/flatcar/Flatcar/issues/2111 because when it iterates
over the list of sub mounts it doesn't expect entries with NULL in the
path from the dropped entries.
Instead of having to deal with entries with path NULL, better sort the
holes from dropping to the end and then reduce the array length.
Drop the -fundamental suffix from src/fundamental/ headers in favor of names
that match their src/basic/ or src/shared/ counterparts (e.g.
macro-fundamental.h -> macro.h, assert-fundamental.h -> assert-util.h,
cleanup-fundamental.h -> cleanup-util.h). Rename src/basic/{btrfs,label}.{c,h}
to use the -util suffix to match the existing shared/btrfs-util and
shared/label-util siblings. Rename src/shared/mkdir-label.{c,h} to mkdir.{c,h}
and src/shared/tmpfile-util-label.{c,h} to tmpfile-util.{c,h} to match the
corresponding src/basic names.
This saves us from having to come up with separate names for files that do
the same thing across tiers, and it makes it easier to move stuff between
src/fundamental, src/basic and src/shared: consumers just #include "foo.h"
and pick up whichever tier their -I path resolves to first, so call sites
don't need to be updated when an API moves between layers.
Where a higher-tier wrapper exists (e.g. src/basic/macro.h wrapping
src/fundamental/macro.h), the wrapper uses an explicit "../fundamental/foo.h"
or "../basic/foo.h" relative include for the lower-tier header. We can't use
GCC's #include_next directive for this — when the wrapper is reachable both
via same-dir-as-source lookup and via -I (e.g. -Isrc/shared) for the
directory it lives in, #include_next advances by exactly one slot in libcpp's
internal directory chain and lands on the same physical directory it was
already in, never reaching the lower-tier sibling (see make_cpp_dir() in
gcc/libcpp/files.cc:1986).
To make sure the right headers are always picked up, the include directories
are reordered so that e.g. src/shared always takes priority over src/basic and
similar for the other directories.
Co-developed-by: Claude Opus 4.7 <noreply@anthropic.com>
Every dlopen_xxx() helper now takes an int log_level argument. It is
passed through to dlopen_many_sym_or_warn() (which in turn propagates it
to dlopen_verbose() for the library-not-installed case), and is used by
the fallback stub when support for the library is not compiled in to
emit a "<lib> support is not compiled in." message at the caller's level.
Callers pass LOG_DEBUG when gracefully degrading, or a higher level when
the failure should surface, and no longer need to log redundantly at the
call site.
As part of this, dlopen_bpf_full() (which already took a log_level) is
merged into dlopen_bpf() rather than keeping both.
The static inline fallbacks used to live in the headers, which required
pulling log.h in from every header that declared a dlopen_xxx(). Move
them into the .c files instead: the declaration is always outside the
#if HAVE_XXX block, the impl sits outside the outer #if HAVE_XXX wrap
with its own internal #if HAVE_XXX/#else/#endif, and apparmor-util.c,
idn-util.c, libmount-util.c and pam-util.c are now always compiled so
they can host their stubs.
The kernel prevents you from open_tree()'ing an open_tree() fd unless it
was created from the caller's mount namespace. For various use cases, we
want to be able to open_tree() arbitrary mount file descriptors. Turns
out there's a way go get around it by mounting the mount file descriptor
in a throw-away mount namespace and then open_tree()'ing the mount file
descriptor. Let's implement this as a new helper mount_fd_clone() and
add a test for it.
Because move_mount()'ing the original fd makes it pretty useless as it
can't be move_mount()'ed again, we optionally make a second clone which
can replace the original fd so it can be cloned again later.
Currently, if the libmount feature is disabled, we don't build
libshared and as a result skip building every other executable as
well. Among other things, this makes our nodeps CI builds kind of
pointless since hardly any code will be compiled.
Let's improve on the situation by making libmount properly optional
in libshared. Then, we only skip building the executables that
actually need libmount.
Submounts will always be located further in the mountinfo file, so
when we're unmounting, iterating backwards is likely to be more
efficient than iterating forwards. It'll also reduce the amount of
EBUSY debug logging we'll get since we'll stop trying to unmount
parent mounts with submounts which will always fail with EBUSY.
Then, move syscall definitions to the wrapper, and prototypes are moved
to relevant headers.
This also adds checks for add_key() and request_key(), as one day
glibc may be going to add some of them separatedly.
The check for fspick in meson.build is dropped, as it is currently
unused in our code.
This also moves
- basic/missing_bpf.h -> include/override/linux/bpf.h,
- basic/missing_keyctl.h -> include/override/linux/keyctl.h.
Christian made this possible in Linux 6.15 with a new system call
open_tree_attr() that combines open_tree() and mount_setattr().
Because idmapped mounts are (rightfully) not nested, we have to do
some extra shenanigans to make source we're putting the right source
uid in the userns for any idmapped mounts that we do in nspawn.
Of course we also add the necessary boilerplate to make open_tree_attr()
available in our code and wrap open_tree_attr() and the corresponding
fallback in a new function which we then use everywhere else.
I wanted to see if moving moving out constant string arguments our of
error messages results in smaller binary sizes. Turns out it does, but
the savings are not consistent. Sometimes we get a few kB in a single
binary, sometimes there is no size change.
git grep -l 'Failed to open /'|xargs sed -r -i 's|"Failed to open (/[^ ]+): %m"|"Failed to open %s: %m", "\1"|g'
git grep -l $'Failed to open \'/'|xargs sed -r -i $'s|"Failed to open \'(/[^ ]+)\': %m"|"Failed to open %s: %m", "\\1"|g'
git grep -l "Failed to open /"|xargs sed -r -i $'s|"Failed to open (/[^ ]+), ignoring: %m"|"Failed to open %s, ignoring: %m", "\\1"|g'
+ some manual fixups.
If .attr_set is zero (and .att_clr, .propagation too), then there's no
point in calling mount_setattr().
Fixes: #37062
Note that this optimization is not precisely load-bearing anymore, since
3cc23a2c23 got merged which removes the
only caller of make_fsmount() that might trigger it. But it's worth
fixing generic code anyway, in case it gets used like this later again.
`ExtensionImages=` and `ExtensionDirectories=` now let you specify
vpick-named extensions; however, since they just get set up once when
the service is started, you can't see newer versions without restarting
the service entirely. Here, also reload confext extensions when you
reload a service. This allows you to deploy a new version of some
configuration and have it picked up at reload time without interruption
to your workload.
Right now, we would only reload confext extensions and leave the sysext
ones behind, since it didn't seem prudent to swap out what is likely
program code at reload. This is made possible by only going for the
`SYSTEMD_CONFEXT_HIERARCHIES` overlays (which only contains `/etc`).
Implementation wise, this uses the new kernel API and two collaborating
child processes under the host & child namespaces in order to gather the
right FDs needed:
- (1) In child, set up the extension images and directories in a slave
mountns, and obtain their FDs.
- (2) Fork into a grandchild under target process namespace, and do a
"fake" unmount to obtain the FD of the underlying target folder
say /etc).
- (3) In the child again, set up new overlay under host NS rights.
We do not want to do I/O heavy jobs inline in PID1 blocking the state
machine, so add separate async states to handle this case.
Co-authored-by: Luca Boccassi <luca.boccassi@gmail.com>
DDIs may contain multiple versions of the same OS, or even multiple
OSes. Hence it makes sense to not just pick the "newest", whatever that
might be, but only partitions associated with specific images, or in a
specific version.
Let's a concept for such filtering: a per-designator glob expression
that can be applied to the partition label string, and can be used for
such filtering.
Usecase: when picking UKI belonging to OS image X in version Y, make
sure we only pick a /usr/ partition belonging to X in version Y, and a
root and home partition belonging to X in any version.
This only adds the basic infrastructure, but doesn't actually expose it
anywhere.
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.
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.
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.
This replaces make_mount_point_inode_from_stat() by
make_mount_point_inode_from_mode() and makes it take a single mode_t
rather than a "struct stat". Moreover, at an "atfd" style directory
parameter.
Then port all users over to new feature, and in particular make use of
the directory fd: use chase() to create and pin parent directories first where
needed.
This introduces libmount_parse_mountinfo() and libmount_parse_with_utab().
The former one parses only mountinfo, but the latter one also parse
utab. Hopefully this avoids pitfalls like issue #35949.
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)
- 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)
Kai Lüke
Daan De Meyer
Zbigniew Jędrzejewski-Szmek
Luca Boccassi
Mike Yuan
Daan De Meyer
Yu Watanabe
Lennart Poettering
Jelle van der Waa
Zbigniew Jędrzejewski-Szmek
maia x.andLuca Boccassi