This also switches all these notes to be defined via SD_ELF_NOTE_DLOPEN_ANCHORED().
Consequently, any notes added within unreachable or unused functions will be
automatically garbage-collected by the linker (--gc-sections) instead of
bloating the final binary.
E.g. unused p11-kit library dependency is now dropped from
systemd-repart.standalone binary.
Before:
```
$ systemd-analyze dlopen-metadata build/systemd-repart.standalone
FEATURE DESCRIPTION SONAME PRIORITY
cryptsetup Support for disk encryption, integrity, and authentication libcryptsetup.so.12 recommended
blkid Support for block device identification libblkid.so.1 required
libcrypto Support for cryptographic operations libcrypto.so.4 libcrypto.so.3 recommended
mount Support for mount enumeration libmount.so.1 required
fdisk Support for reading and writing partition tables libfdisk.so.1 required
blkid Support for block device identification libblkid.so.1 recommended
libcrypto Support for cryptographic operations libcrypto.so.4 libcrypto.so.3 suggested
cryptsetup Support for disk encryption, integrity, and authentication libcryptsetup.so.12 suggested
fdisk Support for reading and writing partition tables libfdisk.so.1 suggested
idn Support for internationalized domain names libidn2.so.0 suggested
mount Support for mount enumeration libmount.so.1 recommended
selinux Support for SELinux libselinux.so.1 recommended
tpm Support for TPM libtss2-esys.so.0 suggested
tpm Support for TPM libtss2-rc.so.0 suggested
tpm Support for TPM libtss2-mu.so.0 suggested
tpm Support for TPM libtss2-tcti-device.so.0 suggested
p11-kit Support for PKCS11 hardware tokens libp11-kit.so.0 suggested
```
After:
```
$ systemd-analyze dlopen-metadata build/systemd-repart.standalone
FEATURE DESCRIPTION SONAME PRIORITY
cryptsetup Support for disk encryption, integrity, and authentication libcryptsetup.so.12 recommended
blkid Support for block device identification libblkid.so.1 required
libcrypto Support for cryptographic operations libcrypto.so.4 libcrypto.so.3 recommended
mount Support for mount enumeration libmount.so.1 required
fdisk Support for reading and writing partition tables libfdisk.so.1 required
blkid Support for block device identification libblkid.so.1 recommended
libcrypto Support for cryptographic operations libcrypto.so.4 libcrypto.so.3 suggested
cryptsetup Support for disk encryption, integrity, and authentication libcryptsetup.so.12 suggested
fdisk Support for reading and writing partition tables libfdisk.so.1 suggested
mount Support for mount enumeration libmount.so.1 recommended
selinux Support for SELinux libselinux.so.1 recommended
tpm Support for TPM libtss2-esys.so.0 suggested
tpm Support for TPM libtss2-rc.so.0 suggested
tpm Support for TPM libtss2-mu.so.0 suggested
tpm Support for TPM libtss2-tcti-device.so.0 suggested
```
By chance (because I had this mistake in my own commit) I noticed
that there are a bunch of duplicated works like "the the" in the
code and man-pages.
This commit fixes them and some similar issues with "and and" etc.
Mirror how chaseat() works these days: instead of a single toplevel_fd that
serves as both the root (chroot) boundary and the directory that resolution
starts from, path_pick() now takes a separate root_fd and dir_fd. This lets
callers resolve a path relative to a specific directory fd while confining
symlink and absolute-path resolution to a root directory fd.
All existing callers are updated to pass the same fd for both, preserving
their current behaviour.
Switch the executable-owned call sites from the plain dlopen_<lib>()
helpers to the new DLOPEN_<LIB>() macros, so that each binary that loads
an optional library at runtime now carries its own .note.dlopen note
instead of relying solely on libsystemd-shared. Each call site passes a
priority reflecting whether it hard-depends on the library (required) or
degrades gracefully without it (recommended).
Co-developed-by: Claude Opus 4.8 <noreply@anthropic.com>
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.
fd_is_fs_type() returns < 0 for errors, 0 for false, and > 0 for true, so
in the r > branch we'd most likely report EPERM together with the error
message which is misleading.
This is similar to DEFINE_POINTER_ARRAY_FREE_FUNC, but one
pointer chase less. The name of the outer and inner functions are
specified separately. The inner function does not free, so it'll
be generally something like 'foo_done', but the outer function
does free, so it can be called 'foo_array_free'.
[] has higher precedence than pointer dereference, hence hilarity
ensues as soon as there are multuple images
Originally reported on yeswehack.com as:
YWH-PGM9780-122
Follow-up for dfdeb0b1cb
With the previous changes the modes for /tmp/ and /var/tmp/
may come in arbitrary directions, i.e. we may downgrade one
and upgrade another. Hence let's refactor the setup logic
a bit so they're truly independent.
In https://github.com/systemd/systemd/issues/28515, multiple people report that
services that have PrivateTmp=yes and DefaultDependencies=no fail to create the
temporary directories under /tmp, when /tmp is e.g. a bind mount or some other
kind of mount that takes more time.
Before PrivateTmp=disconnected was added, we didn't have a nice solution:
DefaultDependencies=no is used to start services very early, so we wouldn't
want to add a dependency on /tmp automatically. With PrivateTmp=disconnected we
have a fairly nice solution. Let's "upgrade" to this mode automatically.
Strictly speaking, it is a small compat break, but in practice it's unlikely to
matter for early-boot services whether their /tmp is private or disconnected.
The dependency on /tmp that is checked is After. I think this is enough,
since any tmp.mount would be pulled in by local-fs.target and the rest of
the transaction anyway, so we don't need to check more than After.
The asserts are relaxed, because now the two settings can now diverge
in either way.
Resolves https://github.com/systemd/systemd/issues/28515.
[yhndnzj: fix unit_add_exec_dependencies() to handle the new
combination; add a comment in exec_needs_sys_admin()]
* Make sure we're not passing NULL to rmdir()
* Remove the inner "tmp" subdir as well, so that callers
can handle this transparently (e.g. exec_shared_runtime_make()
is not aware of the nested rmdir() requirements)
While at it, remove unneeded PROTECT_ERRNO.
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.)
So far we opened a new Varlink connection for every mountfsd/nsresourced
method call. Given each tool only does a very small number of calls
(usually 1…5) on them and the connections are cheap this is not too
wasteful. Nonetheless, let's do something about it, and allow reusing
the connection for multiple calls.
This not only makes things a bit more efficient, but has one more
important benefit: Varlink connections pin the security context of the
client when connecting. This means that varlink method calls done with a
connection established while some code was privileged will still operate
as privieged once privs are dropped, until the connection is closed.
This pinning effect is really nice, as it gives us behaviour in a
"capability system" like scheme. Later code is going to use that to
continue doing certain priv userns ops even after unsharing userns and
becoming fully unpriv.
A later commit will add transient allocation of user namespaces with
dynamic UID range assignment. That creates certain permission issues.
Let's hence allow them to be handled gracefully in case the 'ignore'
field is set for a mount.
This is not just refactoring, but has the big benefit that it makes us
indepdendent from a temporary directory we might not have enough access
to create. (This matters with the new PrivateUsers=managed).
Starting from cfbf7538d8 we'd always
install the credentials dir regardless of whether it's empty,
with the correct permissions. Hence the problem stated in the comment
should no longer be a concern. Moreover, this ensures later in
setup_namespace() the mountpoint would be in-place. This is important
for credential reloading as it saves the trouble of remounting
the upper tmpfs as rw again and create the mountpoint.
If we fail to create a parent directory, then the error from
make_mount_point_inode_from_path() will always be
"No such file or directory" which doesn't tell us anything. Add logging
for the mkdir_parents() call as well so we get a useful error.
RootImageOptions=/ExtensionImages=/MountImages= all support custom
mount options, but mountfsd does not support it. Add varlink
parameters to allow callers to specify mount options so that
those directives can work as expected. Require additional privs via
polkit.
Currently, pick_filter_image_any matches any image
with any suffix, which is way more than it should
be doing. It should only be matching images with
the .raw suffix.
Let's address this shortcoming by allowing to pass
multiple filters to path_pick(), and define
pick_filter_image_any as the combination of the
raw and directory image filters.
Fixes#40083
RootImageOptions=/ExtensionImages=/MountImages= all support
custom mount options, use the new mountfsd parameters to
configure them if they are specified.
This requires additioanl privileges via polkit due to security
implications of mount options, so document an example policy
that allows to use the nosuid mount option.
Currently mount options are handled in such a way that the first
definition for a given partition wins, and documented as such.
Change them so that they behave like other options, and the
last specified wins.
Applies to RootImageOptions=, MountImages= and ExtensionImages=.
Switch from a linked list to an array indexed by the partition
specifier to store them.
Transparent Hugepages (THP) is a Linux kernel feature that manages
memory using larger pages (2MB on x86, compared to the default 4KB).
The main goal is to improve memory management efficiency and system
performance, especially for memory-intensive applications.
However, it can cause drawbacks in some scenarios, such as memory
regression and latency spikes. THP policy is governed for the entire
system via /sys/kernel/mm/transparent_hugepage/enabled.
However, it can be overridden for individual workloads via prctl(2)
call.
MemoryTHP= is used to disable THPs at exec-invoke to stop
providing THPs for workloads where the drawbacks outweigh the advantages.
When set to "disable", MemoryTHP= disables THPs completely for the
process, irrespecitive of global THP controls.
When set to "madvise", MemoryTHP= disables THPs for the process except
when specifically madvised by the process with MADV_HUGEPAGE or MADV_COLLAPSE.
The verity user certs weren't looked up in the given --root= for
systemd-sysext which made it fail to set up extensions with a strict
image policy.
Look up verity user certs from inside the --root= when we operate on
images in it. The main use case where this matters is when the initrd
sets up the extensions for the final system and thus systemd-sysext
should do the same thing as it would do in the final system.
Loading images is, generally speaking, the slowest part of sd-executor
when spawning a service. This is due to multiple factors. dm-verity is
obviously a big part of the cost, but dissecting in general via libblkid
also can take a lot of time, due to probing the images and their filesystems.
A performance test doing service restarts in a row shows these
results, ran on a production system (low power and slow ARM64 SOC) with
a real production service, show the following service interruption intervals:
Count | P50 (ms) | P90 (ms) | P95 (ms) | P99 (ms) | P99.9 (ms)
507 | 1,532 | 1,726 | 2,548 | 4,112 | 4,592
One iteration is 507 restarts in this case, but this has ran hundreds
of times and the results are always in line within margin of error.
This also holds true for metrics from live systems, same numbers.
Between 1.0s and 1.2s can be attributed by profiling to the time needed
for the service code itself to start up and sd_notify, the rest is spent
inside systemd's code.
This means there is currently a tradeoff for services - either use secure
images, or make restarting fast. Downtime of services is a very important
metric, as for many cases this directly translates to outages, total or
partial (blackouot or greyout).
In order to facilitate using secure images without downsides, skip the
slow dissect steps (probing, loop devices, etc) when the configured
image is a single filesystem dm-verity image with a policy that pins it
to a single filesystem, and an already existing and open dm-verity device
can be found and reused.
This allows orchestrators to pre-open images on download, before restarting
services, to minimize downtimes.
Follow-up for a08f2ea02d
This fixes extensions refreshing + verity-protected DDIs.
TEST-50-DISSECT previously passed because confext refreshing
is tested after live mount, the latter of which used to
load libcryptsetup in pid1.
Saying "table" everywhere is not needed. Everybody can see that the table
is a table is a table. Also tweak the grammar in various places to make
reading nicer.
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.
Needed to implement support for RootHashSignature=/RootVerity=/RootHash=
and friends when going through mountfsd, for example with user units,
so that system and user units provide the same features at the same
level
Previously, we'd take the image policy only into consideration when
dissecting the mage, but for the unlock/verity step we'd go via best
effort. Change that. This means we can now enforce policies such as
activating by root hash only even if a signature exists and similar.
Also, introduce a separate error code if we try to unlock a Verity
volume but have no root hash. Previously we'd return ENOKEY for that,
exactly like we do for encrypted volumes where we have no passparse. The
interctive unlock loop dissected_image_decrypt_interactively() is
otherwise very confused and will ask for a root hash, which makes no
sense. Hence use two distinct errors for this.
Sharing verity volumes is problematic for a veriety of reasons, for
example because it might pin the wrong backing device at the wrong time.
Let's hence turn this around: unless verity sharing is enabled, leave it
off, and turn $SYSTEMD_VERITY_SHARING into a true boolean that can be
set both ways.
The primary usecase for verity sharing is RootImage=, where it probably
makes sense to leave on, hence set the flag there.
This is crucial when putting together installers which install an OS on
a second disk: if verity sharing is always on we might mount the wrong
of the two disks at the wrong time.
Yu Watanabe
Michael Vogt
Lennart Poettering
Luca Boccassi
Daan De Meyer
Frantisek Sumsal
Zbigniew Jędrzejewski-Szmek
Mike Yuan
Zbigniew Jędrzejewski-Szmek
Daan De Meyer
Luca Boccassi
Usama Arif
Kai Lueke
Lennart Poettering