This opens the door for making the call work without privileges: if we
pass in a userns fd and DissectedImage that has mount fds then we can
acquire all information without privs.
When adding unprivileged nspawn support we don't really want a global
lock file, since we cannot even access the dir they are stored in, hence
make the concept optional.
Some minor other modernizations.
This is similar to uid_range_load_userns() but instead of reading the
uid_map off a process it reads it off a userns fd.
(Of course the kernel has no API for this right now, hence we fork off a
throw-away process which joins the user namespace, and then read off the
data from there.)
This new call takes two image policy objects and generates an
"intersection" policy, i.e. only allows what is allowed by both. Or in
other words it conceptually implements a binary AND of the policy flags.
(Except that it's a bit harder, due to normalization, and underspecified
flags).
We can use this later for mountfsd: a client can specify a policy, and
mountfsd can specify another policy, and we'll then apply only what both
allow.
Note that a policy generated like this might be invalid. For example, if
one policy says root must exist and be verity or luks protected, and the
other policy says root must be absent, then the intersection is invalid,
since one policy only allows what the other prohibits and vice versa.
We'll return a clear error code in that case (ENAVAIL). (This is because
we simply don't allow encoding such impossible policies in an
ImagePolicy structure, for good reasons.)
This new call is like varlink_peek_fd() (i.e. gets an fd out of the
connection but leaving it also in there), and combines ith with
F_DUPFD_CLOEXEC to make a copy of it.
We previously already had varlink_dup_fd() which was a duplicating
version for pushing an fd *into* the connection. To reduce confusion,
let's rename that one varlink_push_dup_fd() to make the symmetry to
valrink_push_fd() clear so that we have no:
varlink_peer_push_fd() → put fd in without dup'ing
varlink_peer_push_dup_fd() → same with F_DUPFD_CLOEXEC
varlink_peer_peek_fd() → get fd out without dup'ing
varlink_peer_peek_dup_fd() → same with F_DUPFD_CLOEXEC
Since e56a8790a0 debugging test-execute fails has been a royal PITA, since
we ditch all potentially useful output from the test units (that, for
the most part, run `sh -x ...`). Let's improve the situation a bit by
setting EXEC_OUTPUT_NULL only when running the single test case that
needs it, and inheriting stdout otherwise.
For example, with a purposefully introduced error we get this output
with this patch:
exec-personality-x86-64.service: About to execute: sh -x -c "c=\$\$(uname -m); test \"\$\$c\" = \"foo_bar\""
Serializing sd-executor-state to memfd.
...
Personality: x86-64
LockPersonality: no
SystemCallErrorNumber: kill
++ uname -m
+ c=x86_64
+ test x86_64 = foo_bar
Received SIGCHLD from PID 1520588 (sh).
Child 1520588 (sh) died (code=exited, status=1/FAILURE)
exec-personality-x86-64.service: Child 1520588 belongs to exec-personality-x86-64.service.
exec-personality-x86-64.service: Main process exited, code=exited, status=1/FAILURE
exec-personality-x86-64.service: Failed with result 'exit-code'.
...
Exit Status: 1
src/test/test-execute.c:456:test_exec_personality: exec-personality-x86-64.service: can_unshare=yes: exit status 1, expected 0
(test-execute-root) terminated by signal ABRT.
Assertion 'r >= 0' failed at src/test/test-execute.c:1433, function prepare_ns(). Aborting.
Aborted
But without it, we'd miss the most important part:
exec-personality-x86-64.service: About to execute: sh -x -c "c=\$\$(uname -m); test \"\$\$c\" = \"foo_bar\""
Serializing sd-executor-state to memfd.
...
Personality: x86-64
LockPersonality: no
SystemCallErrorNumber: kill
Received SIGCHLD from PID 1521365 (sh).
Child 1521365 (sh) died (code=exited, status=1/FAILURE)
exec-personality-x86-64.service: Child 1521365 belongs to exec-personality-x86-64.service.
exec-personality-x86-64.service: Main process exited, code=exited, status=1/FAILURE
exec-personality-x86-64.service: Failed with result 'exit-code'.
...
Exit Status: 1
src/test/test-execute.c:456:test_exec_personality: exec-personality-x86-64.service: can_unshare=yes: exit status 1, expected 0
(test-execute-root) terminated by signal ABRT.
Assertion 'r >= 0' failed at src/test/test-execute.c:1433, function prepare_ns(). Aborting.
Aborted
Currently, the memory management of service_set_main_pidref
is a bit odd. Normally we either invalidate the original
resource on caller's side after the call succeeds, or
just pass the ownership wholly. But service_set_main_pidref
take a pointer, and calls pidref_done() internally.
Let's just make it consume the passed pidref. This is more
straightforward.
On s390x both __s390__ and __s390x__ are defined, and with the original
order we'd go through the __s390__ branch and emit a warning:
[169/2118] Compiling C object src/shared/libsystemd-shared-256.a.p/base-filesystem.c.o
../src/shared/base-filesystem.c:136:11: note: ‘#pragma message: Please add an entry above specifying whether your architecture uses /lib64/, /lib32/, or no such links.’
136 | # pragma message "Please add an entry above specifying whether your architecture uses /lib64/, /lib32/, or no such links."
| ^~~~~~~
If we're running test-execute from the build directory which is under
one of the tmpfs-ed directories (i.e. /root or /tmp), test-execute might
behave strangely, since in that case manager_new() pins the system
systemd-executor binary instead of the build dir one, which may lead to
a very confusing test fails (if there's enough difference between the
system and built sd-executor binary). Let's account for that and
bind-mount the build dir under the tmpfs-ed directory if necessary.
On s390x this test fails when the SUT uses the z90crypt kernel module,
as it's an another FD the test doesn't account for:
/* test_rearrange_stdio */
Successfully forked off 'rearrange' as PID 57293.
test_rearrange_stdio: r=0
/proc/57293/fd:
total 0
lrwx------. 1 root root 64 Apr 5 06:18 0 -> /dev/pts/0
lrwx------. 1 root root 64 Apr 5 06:18 1 -> /dev/pts/0
lrwx------. 1 root root 64 Apr 5 06:18 2 -> /dev/pts/0
lrwx------. 1 root root 64 Apr 5 06:18 3 -> /dev/z90crypt
rearrange terminated by signal ABRT.
Debugging this was pain, since the child process didn't log anything
once we closed stdout/stderr (for obvious reasons). Let's fix both
issues by switching logging to kmsg once we close stdin/stdout/stderr,
and also by making the test work fine when there are some extra FDs in
the child's environment.
Currently, when downgrading from a version with pidfd support to a
version without pidfd support, all information about running processes
is lost as the newer systemd will serialized pidfds which are not recognized
by the older systemd when deserializing.
To improve the situation, let's serialize both the pid and the pidfd.
This is safe because existing versions will either replace the first
deserialized pidref with the second one or discard the second one in
favor of the first one depending on the unit and field. Older versions
that don't support pidfd's will silently discard any fields that contain
a pidfd as those will try to parse the field as a pid and since a pidfd
field will start with '@', those versions will debug error log and ignore
the value.
To make sure we reuse the existing pidfd as much as possible, the pidfd
is serialized first. Both for scopes and service main pids, if the same
pid is seen multiple times, the first pidref is kept. So by serializing
the pidfd first we make sure the original pidfd is used instead of the
new one which is opened when deserializing the first pid field.
For other control units, older versions with pidfd support will discard
the first pidfd and replace it with a new pidfd from the second pid field.
This is a slight regression on downgrades, but we make sure it doesn't
happen for future versions (and older versions when this commit is
backported) by modifying the logic to only use the first successfully
deserialized pidref so that the raw pid without pidfd is discarded instead
of it replacing the existing pidfd.
There are bugs in the kernel verifier that cause legitimate code
to be rejected, disabling this optimization makes bpf programs
built with a new enough gcc work again.
Fixes https://github.com/systemd/systemd/issues/31888
Follow-up for e0504dd011.
Hopefully, devices in PCI subsystem have some properties, thus have
their udev database file. But, that may not be true. Here, we only read
sysattrs of enumerated devices, hence it is not necessary to check if
the device is initialized or not.
