When we do a MS_BIND mount, it inherits the flags of its parent mount.
When we do a remount, it sets the flags to exactly what is specified.
If we are in a user namespace then these mount points have their flags
locked, so you can't reduce the protection.
As a consequence, the default setup of mount_all doesn't work with user
namespaces. However if we ensure we add the mount flags of the parent
mount when remounting, then we aren't removing mount options, so we
aren't trying to unlock an option that we aren't allowed to.
In such a case let's suppress the warning (downgrade to LOG_DEBUG),
under the assumption that the user has no config file to update in its
place, but a symlink that points to something like resolved's
automatically managed resolve.conf file.
While we are at it, also stop complaining if we cannot write /etc/resolv.conf
due to a read-only disk, given that there's little we could do about it.
If the kernel do not support user namespace then one of the children
created by nspawn parent will fail at clone(CLONE_NEWUSER) with the
generic error EINVAL and without logging the error. At the same time
the parent may also try to setup the user namespace and will fail with
another error.
To improve this, check if the kernel supports user namespace as early
as possible.
This ports a lot of manual code over to sigprocmask_many() and friends.
Also, we now consistly check for sigprocmask() failures with
assert_se(), since the call cannot realistically fail unless there's a
programming error.
Also encloses a few sd_event_add_signal() calls with (void) when we
ignore the return values for it knowingly.
Remove old temporary snapshots, but only at boot. Ideally we'd have
"self-destroying" btrfs snapshots that go away if the last last
reference to it does. To mimic a scheme like this at least remove the
old snapshots on fresh boots, where we know they cannot be referenced
anymore. Note that we actually remove all temporary files in
/var/lib/machines/ at boot, which should be safe since the directory has
defined semantics. In the root directory (where systemd-nspawn
--ephemeral places snapshots) we are more strict, to avoid removing
unrelated temporary files.
This also splits out nspawn/container related tmpfiles bits into a new
tmpfiles snippet to systemd-nspawn.conf
This adds a "char *extra" parameter to tempfn_xxxxxx(), tempfn_random(),
tempfn_ranomd_child(). If non-NULL this string is included in the middle
of the newly created file name. This is useful for being able to
distuingish the kind of temporary file when we see one.
This also adds tests for the three call.
For now, we don't make use of this at all, but port all users over.
seccomp_load returns -EINVAL when seccomp support is not enabled in the
kernel [1]. This should be a debug log, not an error that interrupts nspawn.
If the seccomp filter can't be set and audit is enabled, the user will
get an error message anyway.
[1]: http://man7.org/linux/man-pages/man2/prctl.2.html
Also, when the child is potentially long-running make sure to set a
death signal.
Also, ignore the result of the reset operations explicitly by casting
them to (void).
Rather than checking the return of asprintf() we are checking if buf gets allocated,
make it clear that it is ok to ignore the return value.
Fixes CID 1299644.
Allowed interface name is relatively small. Lets not make
users go in to the source code to figure out what happened.
--machine=debian-tree conflicts with
--machine=debian-tree2
ex: Failed to add new veth \
interfaces (host0, vb-debian-tree): File exists
When systemd-nspawn gets exec*()ed, it inherits the followings file
descriptors:
- 0, 1, 2: stdin, stdout, stderr
- SD_LISTEN_FDS_START, ... SD_LISTEN_FDS_START+LISTEN_FDS: file
descriptors passed by the system manager (useful for socket
activation). They are passed to the child process (process leader).
- extra lock fd: rkt passes a locked directory as an extra fd, so the
directory remains locked as long as the container is alive.
systemd-nspawn used to close all open fds except 0, 1, 2 and the
SD_LISTEN_FDS_START..SD_LISTEN_FDS_START+LISTEN_FDS. This patch delays
the close just before the exec so the nspawn process (parent) keeps the
extra fds open.
This patch supersedes the previous attempt ("cloexec extraneous fds"):
http://lists.freedesktop.org/archives/systemd-devel/2015-May/031608.html
If a symlink to a combined cgroup hierarchy already exists and points to
the right path, skip it. This avoids an error when the cgroups are set
manually before calling nspawn.
Previously all bind mount mounts were applied in the order specified,
followed by all tmpfs mounts in the order specified. This is
problematic, if bind mounts shall be placed within tmpfs mounts.
This patch hence reworks the custom mount point logic, and alwas applies
them in strict prefix-first order. This means the order of mounts
specified on the command line becomes irrelevant, the right operation
will always be executed.
While we are at it this commit also adds native support for overlayfs
mounts, as supported by recent kernels.
Some systems abusively restrict mknod, even when the device node already
exists in /dev. This is unfortunate because it prevents systemd-nspawn
from creating the basic devices in /dev in the container.
This patch implements a workaround: when mknod fails, fallback on bind
mounts.
Additionally, /dev/console was created with a mknod with the same
major/minor as /dev/null before bind mounting a pts on it. This patch
removes the mknod and creates an empty regular file instead.
In order to test this patch, I used the following configuration, which I
think should replicate the system with the abusive restriction on mknod:
# grep devices /proc/self/cgroup
4:devices:/user.slice/restrict
# cat /sys/fs/cgroup/devices/user.slice/restrict/devices.list
c 1:9 r
c 5:2 rw
c 136:* rw
# systemd-nspawn --register=false -D .
v2:
- remove "bind", it is not needed since there is already MS_BIND
v3:
- fix error management when calling touch()
- fix lowercase in error message
We have no such check in any of the other tools, hence don't have one in
nspawn either.
(This should make things nicer for Rocket, among other things)
Note: removing this check does not mean that we support running nspawn
on non-systemd. We explicitly don't. It just means that we remove the
check for running it like that. You are still on your own if you do...
This change makes it so all seccomp filters are mapped
to the appropriate capability and are only added if that
capability was not requested when running the container.
This unbreaks the remaining use cases broken by the
addition of seccomp filters without respecting requested
capabilities.
Co-Authored-By: Clif Houck <me@clifhouck.com>
[zj: - adapt to our coding style, make struct anonymous]
This patch removes includes that are not used. The removals were found with
include-what-you-use which checks if any of the symbols from a header is
in use.
Previously we always invoked the container PID 1 on /dev/console of the
container. With this change we do so only if nspawn was invoked
interactively (i.e. its stdin/stdout was connected to a TTY). In all other
cases we directly pass through the fds unmodified.
This has the benefit that nspawn can be added into shell pipelines.
https://bugs.freedesktop.org/show_bug.cgi?id=87732
nspawn containers currently block module loading in all cases, with
no option to disable it. This allows an admin, specifically setting
capability=CAP_SYS_MODULE or capability=all to load modules.
After all it is now much more like strjoin() than strappend(). At the
same time, add support for NULL sentinels, even if they are normally not
necessary.
We really want /tmp to be properly mounted, especially in containers
that lack CAP_SYS_ADMIN or that are not fully booted up and only get a
shell, hence let's do so in nspawn already.
When we set up a loopback device with partition probing, the udev
"change" event about the configured device is first passed on to
userspace, only the the in-kernel partition prober is started. Since
partition probing fails with EBUSY when somebody has the device open,
the probing frequently fails since udev starts probing/opening the
device as soon as it gets the notification about it, and it might do so
earlier than the kernel probing.
This patch adds a (hopefully temporary) work-around for this, that
compares the number of probed partitions of the kernel with those of
blkid and synchronously asks for reprobing until the numebrs are in
sync.
This really deserves a proper kernel fix.
After all, nspawn can now dissect MBR partition levels, too, hence
".gpt" appears a misnomer. Moreover, the the .raw suffix for these files
is already pretty popular (the Fedora disk images use it for example),
hence sounds like an OK scheme to adopt.
Sometimes udev or some other background daemon might keep the loopback
devices busy while we already want to detach them. Downgrade the warning
about it.
Given that we use autodetach downgrading these messages should be with
little risk.
With this change nspawn's -i switch now can now make sense of MBR disk
images too - however only if there's only a single, bootable partition
of type 0x83 on the image. For all other cases we cannot really make
sense from the partition table alone.
The big benefit of this change is that upstream Fedora Cloud Images can
now be booted unmodified with systemd-nspawn:
# wget http://download.fedoraproject.org/pub/fedora/linux/releases/21/Cloud/Images/x86_64/Fedora-Cloud-Base-20141203-21.x86_64.raw.xz
# unxz Fedora-Cloud-Base-20141203-21.x86_64.raw.xz
# systemd-nspawn -i Fedora-Cloud-Base-20141203-21.x86_64.raw -b
Next stop: teach the import logic to automatically download these
images, uncompress and verify them.
This is useful for nspawn managers that want to learn when nspawn is
finished with initialiuzation, as well what the PID of the init system
in the container is.
This adds three kinds of file system locks for container images:
a) a file system lock next to the actual image, in a .lck file in the
same directory the image is located. This lock has the benefit of
usually being located on the same NFS share as the image itself, and
thus allows locking container images across NFS shares.
b) a file system lock in /run, named after st_dev and st_ino of the
root of the image. This lock has the advantage that it is unique even
if the same image is bind mounted to two different places at the same
time, as the ino/dev stays constant for them.
c) a file system lock that is only taken when a new disk image is about
to be created, that ensures that checking whether the name is already
used across the search path, and actually placing the image is not
interrupted by other code taking the name.
a + b are read-write locks. When a container is booted in read-only mode
a read lock is taken, otherwise a write lock.
Lock b is always taken after a, to avoid ABBA problems.
Lock c is mostly relevant when renaming or cloning images.
Now that networkd's IP masquerading support means that running
containers with "--network-veth" will provide network access out of the
box for the container, let's add a shortcut "-n" for it, to make it
easily accessible.
It does not use any functions from libcap directly. The CAP_* constants in use
through this file come from "missing.h" which will import <linux/capability.h>
and complement it with CAP_* constants not defined by the current kernel
headers.
Add an explicit import of our "capability.h" since it does use the function
capability_bounding_set_drop from that header file. Previously, that header was
implicitly imported through through "cap-list.h".
Tested that "systemd-nspawn" builds cleanly and works after this change.
Also, when booting up an ephemeral container of / use the system
hostname as default machine name.
This way specifiyng -M is unnecessary when booting up an ephemeral
container, while allowing any number of ephemeral containers to run from
the same tree.
This works now:
# systemd-nspawn -xb -D / -M foobar
Which boots up an ephemeral container, based on the host's root file
system. Or in other words: you can now run the very same host OS you
booted your system with also in a container, on top of it, without
having it interfere. Great for testing whether the init system you are
hacking on still boots without reboot the system!
This adds --template= to duplicate an OS tree as btrfs snpashot and run
it
This also adds --ephemeral or -x to create a snapshot of an OS tree and
boot that, removing it after exit.
If the format string contains %m, clearly errno must have a meaningful
value, so we might as well use log_*_errno to have ERRNO= logged.
Using:
find . -name '*.[ch]' | xargs sed -r -i -e \
's/log_(debug|info|notice|warning|error|emergency)\((".*%m.*")/log_\1_errno(errno, \2/'
Plus some whitespace, linewrap, and indent adjustments.
Using:
find . -name '*.[ch]' | while read f; do perl -i.mmm -e \
'local $/;
local $_=<>;
s/(if\s*\([^\n]+\))\s*{\n(\s*)(log_[a-z_]*_errno\(\s*([->a-zA-Z_]+)\s*,[^;]+);\s*return\s+\g4;\s+}/\1\n\2return \3;/msg;
print;'
$f
done
And a couple of manual whitespace fixups.
As a followup to 086891e5c1 "log: add an "error" parameter to all
low-level logging calls and intrdouce log_error_errno() as log calls
that take error numbers", use sed to convert the simple cases to use
the new macros:
find . -name '*.[ch]' | xargs sed -r -i -e \
's/log_(debug|info|notice|warning|error|emergency)\("(.*)%s"(.*), strerror\(-([a-zA-Z_]+)\)\);/log_\1_errno(-\4, "\2%m"\3);/'
Multi-line log_*() invocations are not covered.
And we also should add log_unit_*_errno().
commit 79d80fc146 introduced a regression that
prevents mounting a tmpfs if the mount point already exits in the container's
root file system. This commit fixes the problem by ignoring EEXIST.
--link-journal={host,guest} fail if the host does not have persistent
journalling enabled and /var/log/journal/ does not exist. Even worse, as there
is no stdout/err any more, there is no error message to point that out.
Introduce two new modes "try-host" and "try-guest" which don't fail in this
case, and instead just silently skip the guest journal setup.
Change -j to mean "try-guest" instead of "guest", and fix the wrong --help
output for it (it said "host" before).
Change systemd-nspawn@.service.in to use "try-guest" so that this unit works
with both persistent and non-persistent journals on the host without failing.
https://bugs.debian.org/770275
kdbus has seen a larger update than expected lately, most notably with
kdbusfs, a file system to expose the kdbus control files:
* Each time a file system of this type is mounted, a new kdbus
domain is created.
* The layout inside each mount point is the same as before, except
that domains are not hierarchically nested anymore.
* Domains are therefore also unnamed now.
* Unmounting a kdbusfs will automatically also detroy the
associated domain.
* Hence, the action of creating a kdbus domain is now as
privileged as mounting a filesystem.
* This way, we can get around creating dev nodes for everything,
which is last but not least something that is not limited by
20-bit minor numbers.
The kdbus specific bits in nspawn have all been dropped now, as nspawn
can rely on the container OS to set up its own kdbus domain, simply by
mounting a new instance.
A new set of mounts has been added to mount things *after* the kernel
modules have been loaded. For now, only kdbus is in this set, which is
invoked with mount_setup_late().
The barrier implementation tracks remote states internally. There is no
need to check the return value of any barrier_*() function if the caller
is not interested in the result. The barrier helpers only return the state
of the remote side, which is usually not interesting as later calls to
barrier_sync() will catch this, anyway.
Shut up coverity by explicitly ignoring return values of barrier_place()
if we're not interested in it.
A combination of commits f3c80515c and 79d80fc14 cause nspawn to
silently fail with a commandline such as:
# systemd-nspawn -D /build/extra-x86_64 --bind=/usr
strace shows the culprit:
[pid 27868] writev(2, [{"Failed to create mount point /build/extra-x86_64/usr: File exists", 82}, {"\n", 1}], 2) = 83
Function queries system hostname and applies changes only when necessary. Also,
migrate all client of sethostname to sethostname_idempotent while at it.
Commit 864e17068 ("nspawn: actually allow access to /dev/net/tun in the
container") added "/dev/net/tun" to the list of allowed devices but forgot
to tweak the array length, which caused "/dev/kdbus/*" to be missed.
Since b5eca3a205 we don't attempt to GC
busses anymore when unsent messages remain that keep their reference,
when they otherwise are not referenced anymore. This means that if we
explicitly want connections to go away, we need to close them.
With this change we will no do so explicitly wherver we connect to the
bus from a main program (and thus know when the bus connection should go
away), or when we create a private bus connection, that really should go
away after our use.
This fixes connection leaks in the NSS and PAM modules.
getopt is usually good at printing out a nice error message when
commandline options are invalid. It distinguishes between an unknown
option and a known option with a missing arg. It is better to let it
do its job and not use opterr=0 unless we actually want to suppress
messages. So remove opterr=0 in the few places where it wasn't really
useful.
When an error in options is encountered, we should not print a lengthy
help() and overwhelm the user, when we know precisely what is wrong
with the commandline. In addition, since help() prints to stdout, it
should not be used except when requested with -h or --help.
Also, simplify things here and there.
Based on patch by Michael Marineau <michael.marineau@coreos.com>:
When deriving the network interface name from machine name strncpy was
not properly null terminating the string and the maximum string size as
returned by strlen() is actually IFNAMSIZ-1, not IFNAMSIZ.
String which ended in an unfinished quote were accepted, potentially
with bad memory accesses.
Reject anything which ends in a unfished quote, or contains
non-whitespace characters right after the closing quote.
_FOREACH_WORD now returns the invalid character in *state. But this return
value is not checked anywhere yet.
Also, make 'word' and 'state' variables const pointers, and rename 'w'
to 'word' in various places. Things are easier to read if the same name
is used consistently.
mbiebl_> am I correct that something like this doesn't work
mbiebl_> ExecStart=/usr/bin/encfs --extpass='/bin/systemd-ask-passwd "Unlock EncFS"'
mbiebl_> systemd seems to strip of the quotes
mbiebl_> systemctl status shows
mbiebl_> ExecStart=/usr/bin/encfs --extpass='/bin/systemd-ask-password Unlock EncFS $RootDir $MountPoint
mbiebl_> which is pretty weird
Explicitly initalize descriptors using explicit assignment like
bus_error. This makes barriers follow the same conventions as
everything else and makes things a bit simpler too.
Rename barier_init to barier_create so it is obvious that it is
not about initialization.
Remove some parens, etc.
The Barrier-API simplifies cross-fork() synchronization a lot. Replace the
hard-coded eventfd-util implementation and drop it.
Compared to the old API, Barriers also handle exit() of the remote side as
abortion. This way, segfaults will not cause the parent to deadlock.
EINTR handling is currently ignored for any barrier-waits. This can easily
be added, but it isn't needed so far so I dropped it. EINTR handling in
general is ugly, anyway. You need to deal with pselect/ppoll/... variants
and make sure not to unblock signals at the wrong times. So genrally,
there's little use in adding it.
Two modes are supported: --volatile=yes mounts only /usr into the
container, and a tmpfs as root directory. --volatile=state mounts the
full OS tree in, but overmounts /var with a tmpfs.
--volatile=yes hence boots with an unpopulated /etc and /var, starting
with pristine configuration and state.
--volatile=state hence boots with an unpopulated /var, only starting
with pristine state.
Let's protect ourselves against the recently reported docker security
issue. Our man page makes clear that we do not make any security
promises anyway, but well, this one is easy to mitigate, so let's do it.
While we are at it block a couple of more syscalls that are no good in
containers, too.
The file should have been in /usr/lib/ in the first place, since it
describes the OS container in /usr (and not the configuration in /etc),
hence, let's support os-release files in /usr/lib as fallback if no
version in /etc exists, following the usual override logic.
A prior commit already enabled tmpfiles to create /etc/os-release as a
symlink to /usr/lib/os-release should it be missing, thus providing nice
compatibility with applications only checking in /etc.
While it's probably a good idea if all apps check both locations via a
fallback logic, it is only necessary in the early boot process, as long
as the /etc/os-release symlink has not been restored, in case we boot
with an empty /etc.
