12:42 p.m.
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.
Signed-off-by: Daniel P. Berrangé <berrange(a)redhat.com>
---
meson.build | 26 +++++++++++++++++++-------
meson_options.txt | 2 +-
src/network/bridge_driver_conf.c | 19 ++++++++++++++-----
src/network/bridge_driver_linux.c | 10 ++++++++++
src/network/bridge_driver_nop.c | 13 ++++++++++++-
src/util/virfirewall.c | 6 ++++++
src/util/virfirewall.h | 1 +
7 files changed, 63 insertions(+), 14 deletions(-)
diff --git a/meson.build b/meson.build
index 5c7cd7ec2e..2e8b87280d 100644
--- a/meson.build
+++ b/meson.build
@@ -1647,15 +1647,27 @@ if not get_option('driver_network').disabled() and
conf.has('WITH_LIBVIRTD')
conf.set('WITH_NETWORK', 1)
firewall_backend_priority = get_option('firewall_backend_priority')
- if (not firewall_backend_priority.contains('nftables') or
- not firewall_backend_priority.contains('iptables') or
- firewall_backend_priority.length() != 2)
- error('invalid value for firewall_backend_priority option')
+ if firewall_backend_priority.length() == 0
+ if host_machine.system() == 'linux'
+ firewall_backend_priority = ['nftables', 'iptables']
+ else
+ # No firewall impl on non-Linux so far, so force 'none'
+ # as placeholder
+ firewall_backend_priority = ['none']
+ endif
+ else
+ if host_machine.system() != 'linux'
+ error('firewall backend priority only supported on linux hosts')
+ endif
endif
- conf.set('FIREWALL_BACKEND_PRIORITY_0', 'VIR_FIREWALL_BACKEND_' +
firewall_backend_priority[0].to_upper())
- conf.set('FIREWALL_BACKEND_PRIORITY_1', 'VIR_FIREWALL_BACKEND_' +
firewall_backend_priority[1].to_upper())
- conf.set('FIREWALL_BACKEND_PRIORITY_NUM', firewall_backend_priority.length())
+ backends = []
+ foreach backend: firewall_backend_priority
+ backend = 'VIR_FIREWALL_BACKEND_' + backend.to_upper()
+ backends += backend
+ endforeach
+
+ conf.set('FIREWALL_BACKENDS', ', '.join(backends))
elif get_option('driver_network').enabled()
error('libvirtd must be enabled to build the network driver')
endif
diff --git a/meson_options.txt b/meson_options.txt
index 50d71427cb..2d440c63d8 100644
--- a/meson_options.txt
+++ b/meson_options.txt
@@ -117,7 +117,7 @@ option('dtrace', type: 'feature', value:
'auto', description: 'use dtrace for st
option('firewalld', type: 'feature', value: 'auto', description:
'firewalld support')
# dep:firewalld
option('firewalld_zone', type: 'feature', value: 'auto',
description: 'whether to install firewalld libvirt zone')
-option('firewall_backend_priority', type: 'array', choices:
['nftables', 'iptables'], description: 'order in which to try firewall
backends')
+option('firewall_backend_priority', type: 'array', choices:
['nftables', 'iptables'], value: [], description: 'order in which to
try firewall backends')
option('host_validate', type: 'feature', value: 'auto',
description: 'build virt-host-validate')
option('init_script', type: 'combo', choices: ['systemd',
'openrc', 'check', 'none'], value: 'check', description:
'Style of init script to install')
option('loader_nvram', type: 'string', value: '', description:
'Pass list of pairs of <loader>:<nvram> paths. Both pairs and list items
are separated by a colon.')
diff --git a/src/network/bridge_driver_conf.c b/src/network/bridge_driver_conf.c
index e2f3613a41..9da5e790b7 100644
--- a/src/network/bridge_driver_conf.c
+++ b/src/network/bridge_driver_conf.c
@@ -61,6 +61,7 @@ networkGetDnsmasqCaps(virNetworkDriverState *driver)
static int
virNetworkLoadDriverConfig(virNetworkDriverConfig *cfg G_GNUC_UNUSED,
+ bool privileged,
const char *filename)
{
g_autoptr(virConf) conf = NULL;
@@ -68,13 +69,17 @@ virNetworkLoadDriverConfig(virNetworkDriverConfig *cfg G_GNUC_UNUSED,
bool fwBackendSelected = false;
size_t i;
int fwBackends[] = {
- FIREWALL_BACKEND_PRIORITY_0,
- FIREWALL_BACKEND_PRIORITY_1,
+ FIREWALL_BACKENDS
};
- G_STATIC_ASSERT(G_N_ELEMENTS(fwBackends) == VIR_FIREWALL_BACKEND_LAST);
- G_STATIC_ASSERT(G_N_ELEMENTS(fwBackends) == FIREWALL_BACKEND_PRIORITY_NUM);
+ G_STATIC_ASSERT(G_N_ELEMENTS(fwBackends) > 0 &&
+ G_N_ELEMENTS(fwBackends) <= VIR_FIREWALL_BACKEND_LAST);
int nFwBackends = G_N_ELEMENTS(fwBackends);
+ if (!privileged) {
+ fwBackends[0] = VIR_FIREWALL_BACKEND_NONE;
+ nFwBackends = 1;
+ }
+
if (access(filename, R_OK) == 0) {
conf = virConfReadFile(filename, 0);
@@ -104,6 +109,10 @@ virNetworkLoadDriverConfig(virNetworkDriverConfig *cfg
G_GNUC_UNUSED,
for (i = 0; i < nFwBackends && !fwBackendSelected; i++) {
switch ((virFirewallBackend)fwBackends[i]) {
+ case VIR_FIREWALL_BACKEND_NONE:
+ fwBackendSelected = true;
+ break;
+
case VIR_FIREWALL_BACKEND_IPTABLES: {
g_autofree char *iptablesInPath = virFindFileInPath(IPTABLES);
@@ -187,7 +196,7 @@ virNetworkDriverConfigNew(bool privileged)
configfile = g_strconcat(configdir, "/network.conf", NULL);
- if (virNetworkLoadDriverConfig(cfg, configfile) < 0)
+ if (virNetworkLoadDriverConfig(cfg, privileged, configfile) < 0)
return NULL;
if (g_mkdir_with_parents(cfg->stateDir, 0777) < 0) {
diff --git a/src/network/bridge_driver_linux.c b/src/network/bridge_driver_linux.c
index 35e6bd1154..fe7c6e193c 100644
--- a/src/network/bridge_driver_linux.c
+++ b/src/network/bridge_driver_linux.c
@@ -47,6 +47,11 @@ networkFirewallSetupPrivateChains(virFirewallBackend backend,
virFirewallLayer layer)
{
switch (backend) {
+ case VIR_FIREWALL_BACKEND_NONE:
+ virReportError(VIR_ERR_NO_SUPPORT, "%s",
+ _("No firewall backend is available"));
+ return -1;
+
case VIR_FIREWALL_BACKEND_IPTABLES:
return iptablesSetupPrivateChains(layer);
@@ -417,6 +422,11 @@ networkAddFirewallRules(virNetworkDef *def,
}
switch (firewallBackend) {
+ case VIR_FIREWALL_BACKEND_NONE:
+ virReportError(VIR_ERR_NO_SUPPORT, "%s",
+ _("No firewall backend is available"));
+ return -1;
+
case VIR_FIREWALL_BACKEND_IPTABLES:
return iptablesAddFirewallRules(def, fwRemoval);
diff --git a/src/network/bridge_driver_nop.c b/src/network/bridge_driver_nop.c
index 537b9234f8..7797be1ba8 100644
--- a/src/network/bridge_driver_nop.c
+++ b/src/network/bridge_driver_nop.c
@@ -37,9 +37,20 @@ int networkCheckRouteCollision(virNetworkDef *def G_GNUC_UNUSED)
}
int networkAddFirewallRules(virNetworkDef *def G_GNUC_UNUSED,
- virFirewallBackend firewallBackend G_GNUC_UNUSED,
+ virFirewallBackend firewallBackend,
virFirewall **fwRemoval G_GNUC_UNUSED)
{
+ /*
+ * Shouldn't be possible, since virNetworkLoadDriverConfig
+ * ought to fail to find the required binaries when loading,
+ * so this is just a sanity check
+ */
+ if (firewallBackend != VIR_FIREWALL_NONE) {
+ virReportError(VIR_ERR_NO_SUPPORT, "%s",
+ _("Firewall backend '%s' not available on this
platform"),
+ virFirewallBackendTypeToSTring(firewallBackend));
+ return -1;
+ }
return 0;
}
diff --git a/src/util/virfirewall.c b/src/util/virfirewall.c
index 2219506b18..d374f54b64 100644
--- a/src/util/virfirewall.c
+++ b/src/util/virfirewall.c
@@ -37,6 +37,7 @@ VIR_LOG_INIT("util.firewall");
VIR_ENUM_IMPL(virFirewallBackend,
VIR_FIREWALL_BACKEND_LAST,
+ "none",
"iptables",
"nftables");
@@ -815,6 +816,11 @@ virFirewallApplyCmd(virFirewall *firewall,
}
switch (virFirewallGetBackend(firewall)) {
+ case VIR_FIREWALL_BACKEND_NONE:
+ virReportError(VIR_ERR_NO_SUPPORT,
+ _("Firewall backend is not implemented"));
+ return -1;
+
case VIR_FIREWALL_BACKEND_IPTABLES:
if (virFirewallCmdIptablesApply(firewall, fwCmd, &output) < 0)
return -1;
diff --git a/src/util/virfirewall.h b/src/util/virfirewall.h
index 302a6a4e5b..bce51259d2 100644
--- a/src/util/virfirewall.h
+++ b/src/util/virfirewall.h
@@ -44,6 +44,7 @@ typedef enum {
} virFirewallLayer;
typedef enum {
+ VIR_FIREWALL_BACKEND_NONE, /* Always fails */
VIR_FIREWALL_BACKEND_IPTABLES,
VIR_FIREWALL_BACKEND_NFTABLES,
--
2.45.1