There are two scenarios identified after the recent firewall backend
selection was introduced, which result in libvirtd failing to startup
due to an inability to find either iptables/nftables
- On Linux if running unprivileged with $PATH lacking the dir
containing iptables/nftables
- On non-Linux where iptables/nftables never existed
In the former case, it is preferrable to restore the behaviour whereby
the driver starts successfully. Users will get an error reported when
attempting to start any virtual network, due to the lack of permissions
needed to create bridge devices. This makes the missing firewall backend
irrelevant.
In the latter case, the network driver calls the 'nop' platform
implementation which does not attempt to implement any firewall logic,
just allowing the network to start without firewall rules.
To solve this are number of changes are required
* Introduce VIR_FIREWALL_BACKEND_NONE, which does nothing except
report a fatal error from virFirewallApply(). This code path
is unreachable, since we'll never create a virFirewall
object with with VIR_FIREWALL_BACKEND_NONE, so the error reporting
is just a sanity check.
* Ignore the compile time backend defaults and assume use of
the 'none' backend if running unprivileged.
This fixes the first regression, avoiding the failure to start
libvirtd on Linux in unprivileged context, instead allowing use
of the driver and expecting a permission denied when creating a
bridge.
* Reject the use of compile time backend defaults no non-Linux
and hardcode the 'none' backend. The non-Linux platforms have
no firewall implementation at all currently, so there's no
reason to permit the use of 'firewall_backend_priority'
meson option.
This fixes the second regression, avoiding the failure to start
libvirtd on non-Linux hosts due to non-existant Linux binaries.
* Change the Linux platform backend to raise an error if the
firewall backend is 'none'. Again this code path is unreachable
by default since we'll fail to create the bridge before getting
here, but if someone modified network.conf to request the 'none'
backend, this will stop further progress.
* Change the nop platform backend to raise an error if the
firewall backend is 'iptables' or 'nftables'. Again this code
path is unreachable, since we should already have failed to
find the iptables/nftables binaries on non-Linux hosts, so
this is just a sanity check.
* 'none' is not permited as a value in 'firewall_backend_priority'
meson option, since it is conceptually meaningless to ask for
that on Linux.
NB, 'firewall_backend_priority' allows repeated options temporarily,
which we don't want. Meson intends to turn this into a hard error
DEPRECATION: Duplicated values in array option is deprecated. This will become a hard error in the future.
and we can live with the reduced error checking until that happens.
Reviewed-by: Andrea Bolognani <abologna@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
The virt-pki-validate tool is currently a shell script. We have a
general goal of eliminating use of shell in the project. By doing a
new implementation in C, we can also make use of our more thorough
sanity checking code to validate the certificate setup.
This new implementation the same output format as the host validation
tool for a more consistent user experiance.
It also eliminates the requirement to have certtool installed on
libvirt hosts, which has been an issue for Fedora flatpak packages
since certtool isn't in the default platform runtime.
Reviewed-by: Michal Privoznik <mprivozn@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
The common messaging helpers will be reused in the new impl of the
virt-pki-validate tool.
Reviewed-by: Michal Privoznik <mprivozn@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
The TLS cert validation logic will be reused for the new impl of the
virt-pki-validate tool.
Reviewed-by: Michal Privoznik <mprivozn@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
Updated by "Update PO files to match POT (msgmerge)" hook in Weblate.
Translation: libvirt/libvirt
Translate-URL: https://translate.fedoraproject.org/projects/libvirt/libvirt/
Co-authored-by: Weblate <noreply@weblate.org>
Signed-off-by: Fedora Weblate Translation <i18n@lists.fedoraproject.org>
Support using nftables to setup the firewall for each virtual network,
rather than iptables. The initial implementation of the nftables
backend creates (almost) exactly the same ruleset as the iptables
backend, determined by running the following commands on a host that
has an active virtual network:
iptables-save >iptables.txt
iptables-restore-translate -f iptables.txt
(and the similar ip6tables-save/ip6tables-restore-translate for an
IPv6 network). Correctness of the new backend was checked by comparing
the output of:
nft list ruleset
when the backend is set to iptables and when it is set to nftables.
This page was used as a guide:
https://wiki.nftables.org/wiki-nftables/index.php/Moving_from_iptables_to_nftables
The only differences between the rules created by the nftables backed
vs. the iptables backend (aside from a few inconsequential changes in
display order of some chains/options) are:
1) When we add nftables rules, rather than adding them in the
system-created "filter" and "nat" tables, we add them in a private
table (ie only we should be using it) created by us called "libvirt"
(the system-created "filter" and "nat" tables can't be used because
adding any rules to those tables directly with nft will cause failure
of any legacy application attempting to use iptables when it tries to
list the iptables rules (e.g. "iptables -S").
(NB: in nftables only a single table is required for both nat and
filter rules - the chains for each are differentiated by specifying
different "hook" locations for the toplevel chain of each)
2) Since the rules that were added to allow tftp/dns/dhcp traffic from
the guests to the host are unnecessary in the context of nftables,
those rules aren't added.
(Longer explanation: In the case of iptables, all rules were in a
single table, and it was always assumed that there would be some
"catch-all" REJECT rule added by "someone else" in the case that a
packet didn't match any specific rules, so libvirt added these
specific rules to ensure that, no matter what other rules were added
by any other subsystem, the guests would still have functional
tftp/dns/dhcp. For nftables though, the rules added by each subsystem
are in a separate table, and in order for traffic to be accepted, it
must be accepted by *all* tables, so just adding the specific rules to
libvirt's table doesn't help anything (as the default for the libvirt
table is ACCEPT anyway) and it just isn't practical/possible for
libvirt to find *all* other tables and add rules in all of them to
make sure the traffic is accepted. libvirt does this for firewalld (it
creates a "libvirt" zone that allows tftp/dns/dhcp, and adds all
virtual network bridges to that zone), however, so in that case no
extra work is required of the sysadmin.)
3) nftables doesn't support the "checksum mangle" rule (or any
equivalent functionality) that we have historically added to our
iptables rules, so the nftables rules we add have nothing related to
checksum mangling.
(NB: The result of (3) is that if you a) have a very old guest (RHEL5
era or earlier) and b) that guest is using a virtio-net network
device, and c) the virtio-net device is using vhost packet processing
(the default) then DHCP on the guest will fail. You can work around
this by adding <driver name='qemu'/> to the <interface> XML for the
guest).
There are certainly much better nftables rulesets that could be used
instead of those implemented here, and everything is in place to make
future changes to the rules that are used simple and free of surprises
(e.g. the rules that are added have coresponding "removal" commands
added to the network status so that we will always remove exactly the
rules that were previously added rather than trying to remove the
rules that "the current build of libvirt would have added" (which will
be incorrect the first time we run a libvirt with a newly modified
ruleset). For this initial implementation though, I wanted the
nftables rules to be as identical to the iptables rules as possible,
just to make it easier to verify that everything is working.
The backend can be manually chosen using the firewall_backend setting
in /etc/libvirt/network.conf. libvirtd/virtnetworkd will read this
setting when it starts; if there is no explicit setting, it will check
for availability of FIREWALL_BACKEND_DEFAULT_1 and then
FIREWALL_BACKEND_DEFAULT_2 (which are set at build time in
meson_options.txt or by adding -Dfirewall_backend_default_n=blah to
the meson commandline), and use the first backend that is available
(ie, that has the necessary programs installed). The standard
meson_options.txt is set to check for nftables first, and then
iptables.
Although it should be very safe to change the default backend from
iptables to nftables, that change is left for a later patch, to show
how the change in default can be undone if someone really needs to do
that.
Signed-off-by: Laine Stump <laine@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Tested-by: Daniel P. Berrangé <berrange@redhat.com>
These functions are only ever used by the network driver, and are so
specific to the network driver's usage of iptables that they likely
won't ever be used elsewhere. The files are renamed to
network_iptables.[ch] to be more in line with driver-specific file
naming conventions.
Signed-off-by: Laine Stump <laine@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
This allows users to SSH into a domain with a VSOCK device:
ssh user@qemu/machineName
So far, only QEMU domains are supported AND qemu:///system is
looked for the first for 'machineName' followed by
qemu:///session. I took an inspiration from Systemd's ssh proxy
[1] [2].
To just work out of the box, it requires (yet unreleased) systemd
to be running inside the guest to set up a socket activated SSHD
on the VSOCK. Alternatively, users can set up the socket
activation themselves, or just run a socat that'll forward vsock
<-> TCP communication.
1: https://github.com/systemd/systemd/blob/main/src/ssh-generator/ssh-proxy.c
2: https://github.com/systemd/systemd/blob/main/src/ssh-generator/20-systemd-ssh-proxy.conf.in
Resolves: https://gitlab.com/libvirt/libvirt/-/issues/579
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>
Updated by "Update PO files to match POT (msgmerge)" hook in Weblate.
Translation: libvirt/libvirt
Translate-URL: https://translate.fedoraproject.org/projects/libvirt/libvirt/
Co-authored-by: Weblate <noreply@weblate.org>
Signed-off-by: Fedora Weblate Translation <i18n@lists.fedoraproject.org>
