We unregister binfmt_misc twice during shutdown with this change:
1. A previous commit added support for doing that in the final shutdown
phase, i.e. when we do the aggressive umount loop. This is the robust
thing to do, in case the earlier ("clean") shutdown phase didn't work
for some reason.
2. This commit adds support for doing that when systemd-binfmt.service
is stopped. This is a good idea so that people can order mounts
before the service if they want to register binaries from such
mounts, as in that case we'll undo the registration on shutdown
again, before unmounting those mounts.
And all that, just because of that weird "F" flag the kernel introduced
that can pin files...
Fixes: #14981
Let's just copy out the bit of the string we need, and let's make sure
we refuse rules called "status" and "register", since those are special
files in binfmt_misc's file system.
Apparently if the new "F" flag is used they might pin files, which
blocks us from unmounting things. Let's hence clear this up explicitly.
Before entering our umount loop.
Fixes: #14981
let's return ENOSYS in that case, to make things a bit less confusng.
Previously we'd just propagate ENOENT, which people might mistake as
applying to the object being modified rather than /proc/ just not being
there.
Let's return ENOSYS instead, i.e. an error clearly indicating that some
kernel API is not available. This hopefully should put people on a
better track.
Note that we only do the procfs check in the error path, which hopefully
means it's the less likely path.
We probably can add similar bits to more suitable codepaths dealing with
/proc/self/fd, but for now, let's pick to the ones noticed in #14745.
Fixes: #14745
The setup is meant to run against openSUSE Tumbleweed and install
minimum packages necessary for successful build and passing tests.
To speed up incremental build an external build directory is used.
Otherwise we'd not read the services input while waiting for the job to
wait, and there's no point in waiting for the job anyway if we wait for
the unit to stop ultimately.
Fixes: #15395
Let's be extra careful whenever we return from recvmsg() and see
MSG_CTRUNC set. This generally means we ran into a programming error, as
we didn't size the control buffer large enough. It's an error condition
we should at least log about, or propagate up. Hence do that.
This is particularly important when receiving fds, since for those the
control data can be of any size. In particular on stream sockets that's
nasty, because if we miss an fd because of control data truncation we
cannot recover, we might not even realize that we are one off.
(Also, when failing early, if there's any chance the socket might be
AF_UNIX let's close all received fds, all the time. We got this right
most of the time, but there were a few cases missing. God, UNIX is hard
to use)
ubsan complains that we add an offset to a NULL ptr here in some cases.
Which isn't really a bug though, since we only use it as the end
condition for a for loop, but we can still fix it...
Fixes: #15522
Daan De Meyer