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.
Split the single directory fd that chaseat() used to take into two separate
fds: a root_fd that sets the chroot boundary (symlinks may not escape it,
absolute symlinks resolve relative to it), and a dir_fd that path resolution
starts from. This makes the chroot semantics of chaseat() explicit at every
call site instead of encoding them in the CHASE_AT_RESOLVE_IN_ROOT flag,
which is removed. It also decouples the starting directory from the root
boundary, so callers can descend from any inode inside the tree without
having to reopen the root separately.
XAT_FDROOT passed as root_fd means "no containment" (host root); as dir_fd
it means "start at root_fd". For a smoother transition, AT_FDCWD is also
accepted as root_fd and treated as XAT_FDROOT. When root_fd points to a
directory that is actually the host root, it is normalized to XAT_FDROOT
up front so the existing shortcut path can kick in.
Absolute paths returned by chaseat() are now relative to root_fd, and
relative paths are relative to dir_fd. The result is absolute only when
there is no chroot boundary (root_fd is XAT_FDROOT), or when an absolute
symlink made resolution jump out of the dir_fd subtree; otherwise callers
get a relative path they can feed straight back into an openat()-style
call against dir_fd. Specifically, when dir_fd == root_fd and we're not
operating on the host's root directory, we return a relative path even if
we received an absolute path or resolved an absolute symlink to allow
passing the path directly to openat() style functions. We do this to not
have to go modify every caller of chaseat() to make sure they deal properly
with any absolute paths they might receive. Only when root_fd != dir_fd do
we have to return an absolute path to indicate that the path is relative to
root_fd and not dir_fd.
The shortcut that skips the per-component walk is reworked around a new
chase_xopenat() helper that funnels CHASE_NOFOLLOW, CHASE_MUST_BE_* and
CHASE_TRIGGER_AUTOFS through xopenat_full()'s O_NOFOLLOW, O_DIRECTORY,
XO_REGULAR, XO_SOCKET and XO_TRIGGER_AUTOMOUNT flags. As a result these
flags no longer force us off the shortcut and can be dropped from
CHASE_NO_SHORTCUT_MASK, and the old openat_opath_with_automount() helper
goes away. A CHASE_MUST_BE_ANY alias is introduced for shortcut callers
(stat/access paths) that don't go through xopenat_full() and still need
to bail on those flags locally.
All *_and_* helpers built on top of chaseat() (chase_and_openat,
chase_and_opendirat, chase_and_statat, chase_and_accessat,
chase_and_fopenat_unlocked, chase_and_unlinkat, chase_and_open_parent_at)
gain the same root_fd parameter, and every call site in the tree is
ported to the new signature.
chase_and_open() is also fixed to correctly handle CHASE_EXTRACT_FILENAME
without CHASE_PARENT.
While it is possible to disable sysext/confext merging in the main system
with 'systemctl disable', sysext/confext are always merged in the initrd,
both by systemd-{sys,conf}ext-initrd.service and by
systemd-{sys,conf}ext-sysroot.service and especially the latter can be
unexpected. Provide kernel cmdline options systemd.{sys,conf}ext=0 and
rd.systemd.{sys,conf}ext=0 covering all options.
There are some unnecessary() if() checks for variables
that are already guarded by assert()s. Drop those.
Thanks to keszybz for clarifying the direction of this commit.
I tried to implement a varlink service using sd-varlink, and
not being able to use the approach with sentinel is exteremely
painful. This is useful internally and likewise externally.
The fix in 8f1751a111 made me wonder if we could automatically detect
when pointers are accessed but when this might not be safe. Systemd
is already using a lot of `assert(dst)` and this change now forces
us to use them.
So this commit (ab)uses coccinelle to flag any pointer parameter
dereference not preceded by assert(param), ASSERT_PTR(param), or an
explicit NULL check. It adds integration into meson as a new "coccinelle"
test suite (just like clang-tidy) and is run in CI. The check is not
perfect but seems a reasonable heuristic.
For this RFC commit it is scoped to a subset, it excludes 25 dirs right
now and includes around 100. About 300 warnings left. Busywork that I am
happy to do if there is agreement that it is worth it.
With this in place we would have caught the bug from 8f1751a111 in CI:
```
FAIL: check-pointer-deref.cocci found issues in systemd/src/boot:
diff -u -p systemd/src/boot/measure.c /tmp/nothing/measure.c
--- systemd/src/boot/measure.c
+++ /tmp/nothing/measure.c
@@ -312,7 +312,6 @@ EFI_STATUS tpm_log_tagged_event(
if (err != EFI_SUCCESS)
return err;
- *ret_measured = true;
return EFI_SUCCESS;
}
```
This also adds a new POINTER_MAY_BE_NULL() for the cases when the
called function will do the NULL check (like `iovec_is_set()`).
We often have a pattern where the same verb function is used for
multiple actions. This leads to an antipattern where we figure out what
action needs to be taken from argv[0] multiple times: often once in
parse_argv() to figure out what options are allowed, then once again
implicitly in dispatch_verb(), and then again in the action verb itself.
Let's allow passing a parameter into the verb to simplify this.
This matches a pattern we have in conf-parser.h, where we have both
void *userdata (more global) and void *data (per-config item). Here,
I opted for uintptr_t userdata. It seems that most of the time we'll
want to just pass an enum value. This works OK with no casts. I also
tried a void* and union. In both cases, much more boilerplate is needed:
either a cast or a macro to help avoid compiler warnings. uintptr_t
seems generic enough to cover foreseeable usecases with no fuss.
This is a noop refactoring. See next commit for an example.
If the IDL declares the method requires 'more' yet the call doesn't
have it set, varlink_idl_validate_method_call() should have rejected
it and the callback shouldn't be reached.
When the extensions for the final system are already set up from the
initrd we should avoid disrupting the boot process with the remount
(which currently isn't atomic) and the daemon reload for
systemd-confext and systemd-sysext. Similarly, when sysupdate ran and
updated extensions it's best to avoid the remount and daemon reload if
no changes are found.
To do this, encode the current extension state in more detail than
before where only the names of the extensions where encoded in the
overlay mount. This can also be used to provide more details about the
extension origin in "systemd-sysext status (--json=)". During the
refresh add a check whether the old state matches the new state and in
this case skip the refresh unless the user provides a flag to always
refresh. Besides the extension name and the resolved path the best
method for identification is the verity hash but that is not available
for plain image files or directories. Therefore, also include data to
check for file/directory replacements. The creation/modification times
are not always real on reproducible images or extracted archive content.
The file handle together with the unique mount ID is the next best
identifier we can use when we have no verity hash. Fall back to an inode
when we get no handle. With the creation/modification time and the path
this should be good enough. Using a unique mount ID is important (with
a fallback to the regular non-unique mount ID) instead of st_dev because
st_dev gets reused too easily, e.g., by a loop device mount and the
mount ID helps to catch this. For the mount ID to be valid it has to be
resolved before we enter the new mount namespace. Thus, it gets provided
by the image dissect logic and handed over to the sysext subprocess
which runs in a new mount namespace.
Luckily, we can rule out online modification of directories or image
files because this is anyway not well supported with overlay mounts, so
we don't do a file checksum nor do we recurse into a directory to look
for the most recently touched files. But, as said, with the
always-refresh flag one can force a reload.
When the mutable directory didn't exist but gets created with
--mutable=yes then it used to get mode 700 and later it got patched by
a chmod because it is the top layer and must match the target hierarchy.
This meant one could not call the function to resolve the mutable
directory twice before the mount because it has a check for a proper
mode when the directory exists which is the case for the second call.
Also, this resulted in /var/lib/extensions.mutable getting created with
mode 700 which is not really required.
Don't rely on the chmod for the upper dir but directly create the
directory with the right mode by first creating all missing directories
with 755 as a sane default and then changing the mode as needed for the
mutable directory.
This is needed to set up extension images from the initrd with
`systemd-sysext --root=/sysroot/ merge`.
- vpick: Don't use openat directly but resolve symlinks in given root
With systemd-sysext --root= all symlinks should be followed relative to
the given root and direct openat usage doesn't work.
Remove the openat call and let pin_choice do the work with the chase
helper function to resolve the symlink in the given root.
- discover-image: Follow symlinks in a given root
So far systemd-sysext with --root= specified didn't follow extension
symlinks (such as the "current" symlinks managed by systemd-sysupdate).
The main use case is running systemd-sysext --root=/sysroot for setting
up the overlay mounts already from the initrd.
Resolve symlinks correctly but don't defend against later symlink races
that would access a path outside of the given root. Malicous live
modifications are not a realistic threat model and anyway for that one
would need to rework how the image entry is passed over up to the point
when the loop device is set up. This change here does not introduce this
weakness nor does it expose it more than before. Thus, make it explicit
that setting up the extensions for a given --root= implies a certain
trust into this given root tree that it does not try do race conditions
with symlinks to trick systemd-sysext to mount a file outside --root=.
Without a strict --image-policy= set we would anyway mount filesystems
right away which is another attack vector but, again, the main use case
is to do this for the final system which is trusted at this stage.
- sysext: Use correct image name for extension release checks
For the extension release check the image name is needed and was derived
from the backing file of the loop device. However, this can have a
different name when symlinks were resolved. The surprising behavior was
that it worked when the target name started with the extension name and
_ because that's what's supported to chop off version suffixes. However,
we should not have such strict requirements for the target name and also
allow - as version separator and entirely different names/prefixes, the
same way as we also do for directories instead of raw images.
Do not use the image name derived from the backing file of the loop
device but directly the extension name we have at hand.
- test: Add tests for handling symlinks with systemd-sysext
When we now allow following symlinks inside a --root= we should also
test that it works in various cases from simple relative and absolute
symlinks to .v being a symlink itself or its contents, both for
directory and for .raw image extensions. While at it, also add a simple
test for .v without symlinks which wasn't there for direct usage of
systemd-sysext.
For the extension release check the image name is needed and was derived
from the backing file of the loop device. However, this can have a
different name when symlinks were resolved. The surprising behavior was
that it worked when the target name started with the extension name and
_ because that's what's supported to chop off version suffixes. However,
we should not have such strict requirements for the target name and also
allow - as version separator and entirely different names/prefixes, the
same way as we also do for directories instead of raw images.
Do not use the image name derived from the backing file of the loop
device but directly the extension name we have at hand.
Let's make sure we can safely load configuration files based on a root
fd, including XAT_FDROOT.
(While we are at it, always pass path to root fs before fd to root fs,
following our recently updated CODING_STYLE)
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.
Config files for --root= weren't picked up as expected because the
--root= flag got parsed after the config file.
Switch the order of config file and CLI flag parsing while letting the
CLI flags overwrite things set by the config files by tracking state
during parsing.
Both sysext and confext used the host's /etc/initrd-release file even
when --root=/somewhere was specified. A workaround was the
SYSTEMD_IN_INITRD= env var but without knowing this it was quite
confusing. Aside from users validating their extensions, the primary
use case for this to matter is when the extensions are set up from the
initrd where the initrd-release file is present when running but we want
to prepare the extensions for the final system and thus should match
for the right scope.
Make systemd-sysext check for /etc/initrd-release inside the given
--root= tree. An alternative would be to always ignore the
initrd-release check when --root= is passed but this way it is more
consistent. The image policy logic for EFI-loader-passed extensions
won't take effect when --root= is used, though.
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.
This PR implements what is proposed in
https://github.com/systemd/systemd/issues/37992.
Having a global config file that supports the same cmdline options for
sysext/confext allows the user to customize the behavior of
systemd-sysext.service unit too, without the need of hacking the service
manually.
The global config will live in
`CONF_PATHS_STRV()/systemd/{sysext/confext}.conf` and it will be
overridden by cmdline, so it is possible to customize a run if
`systemd-sysext` is executed manually.
For now support `--mutable=` (`Mutable`) and `--image-policy=`
(`ImagePolicy`).
These images are not using a passphrase, they are using keys
or at most TPM-based sealing (not yet implemented, for contexts).
Do not use the interactive helper, as it will block and ask the
user for a password if it fails to find the signing cert, which
is not useful for this tool.
Fixes https://github.com/systemd/systemd/issues/33179
Introduce systemd/{sysext/confext}.conf and systemd/{sysext/confext}.conf.d to provide an
alternative way of setting the cmdline options in systemd-sysext.
The config file has to have a [Sysext] or [Confext] option respectively,
which will be overridden by the cmdline.
As an example of supported config, add Mutable= option.
Load global sysext/confext from /.extra/global_{sysext,confext} which
systemd-stub puts there from ESP/loader/credentials/*.{sysext,confext}.raw.
Global extensions are handled the exact same way as per-UKI ones.
This commit cleans up the includes for all the small tools across
the tree.
A few cases of returning EXIT_SUCCESS are replaced with returning
0 to avoid including <stdlib.h>.
Split out of #37344.
Let's move some logic from _DEFINE_MAIN_FUNCTION() and other places
in main-func.h into functions that we implement in main-func.c to
allow moving some included headers from the header to the .c file.
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.
When dissecting an image, let's make use of the Verity data even if we
got told no root hash explicitly: we can simply determine it by
concatenating the data partition uuid with the verity partition uuid.
Of course, on first thought this doesn't really add much: if the root
hash is not pinned from somewhere, this does not guarantee trust in
the image.
However, this is very useful for attestation: if we have the root hash
we can measure it before mounting things, even if we don't actually
authenticate it.
Hence, at best this helps us with attestation, at worst it doesn't improve
security but certainly doesn't hurt it.
Christian Brauner
Daan De Meyer
Vitaly Kuznetsov
Michael Vogt
Zbigniew Jędrzejewski-Szmek
Mike Yuan
Kai Lueke
Yu Watanabe
Lennart Poettering
Daan De Meyer
Luca Boccassi
Nick Labich
David Tardon
Pascal Bachor
Zbigniew Jędrzejewski-Szmek
Emanuele Giuseppe Esposito
Christian Glombek