Newer tar started using openat2() via open_subdir() to address
CVE-2025-45582 [0]. Now, gnulib, that tar uses, provides the openat2()
syscall in two ways [1]:
1) If glibc doesn't provide openat2(), it provides its own version in
openat2.c, that tries to call openat2() syscall first, and if it
returns ENOSYS, it emulates the function in userspace.
2) If glibc provides openat2(), it uses that directly, without providing
any fallback on ENOSYS.
Quite recently our test suite started calling nspawn with
--suppress-sync=yes. This means that we call seccomp_suppress_sync(),
which eventually calls block_open_flag(), that blocks the openat2()
syscall completely and refuses it with ENOSYS as this syscall can't be
sensibly filtered (see the openat2()-relevant comments in
block_open_flag() and seccomp_restrict_sxid()). And when glibc provides
openat2(), there's no fallback, so the ENOSYS bubbles up to the user as:
TEST-25-IMPORT.sh[163]: + tar xzf /var/tmp/scratch.tar.gz
TEST-25-IMPORT.sh[163]: tar: ./adirectory/athirdfile: Cannot open: Function not implemented
TEST-25-IMPORT.sh[163]: tar: Exiting with failure status due to previous errors
Let's mitigate this by re-enabling sync for TEST-25-IMPORT, at least for
now.
[0] https://cgit.git.savannah.gnu.org/cgit/tar.git/commit/?id=75b03fdff48916bd0654677ed21379bdb0db016d
[1] https://cgit.git.savannah.gnu.org/cgit/gnulib.git/commit/?id=0b97ffdf32bdab909d02449043447237273df75e
Currently, to run the integration tests, it's still necessary to
install various other build tools besides meson: A compiler, gperf,
libcap, ... which we want to avoid in CI systems where we receive
prebuilt systemd packages and only want to test them. Examples are
Debian's autopkgtest CI and Fedora CI. Let's make it possible for
these systems to run the integration tests without having to install
any other build dependency besides meson by extracting the logic
required to run the integration tests with meson into a separate
subdirectory and adding a standalone top-level meson.build file which
can be used to configure a meson tree with as its only purpose running
the integration tests.
Practically, we do the following:
- all the integration test directories and integration-test-wrapper.py
are moved from test/ to test/integration-test/.
- All the installation logic is kept out of test/integration-test/ or
any of its subdirectories and moved into test/meson.build instead.
- We add test/integration-test/standalone/meson.build to run the
integration tests standalone. This meson file includes
test/integration-test via a cute symlink hack to trick meson into
including a parent directory with subdir().
- Documentation is included on how to use the new standalone mode.
- TEST-64-UDEV-STORAGE and TEST-85-NETWORK are changed to generate separate
units for each testcase to make them behave more like the other integration
tests.
Frantisek Sumsal
Daan De Meyer