The current implementation requires users to configure the preference as such: -Dfirewall_backend_default_1=iptables -Dfirewall_backend_default_2=nftables In addition to being more verbose than one would hope, there are several things that could go wrong. First of all, meson performs no validation on the provided values, so mistakes will only be caught by the compiler. Additionally, it's entirely possible to provide nonsensical combinations, such as repeating the same value twice. Change things so that the preference can now be configured as such: -Dfirewall_backend_priority=iptables,nftables Checks have been added to prevent invalid values from being accepted. Signed-off-by: Andrea Bolognani <abologna(a)redhat.com&gt; --- meson.build | 16 +++++++++------- meson_options.txt | 3 +-- src/network/bridge_driver_conf.c | 6 +++++- src/network/meson.build | 6 ++++-- src/network/network.conf.in | 13 +++++++------ 5 files changed, 26 insertions(+), 18 deletions(-) diff --git a/meson.build b/meson.build index f67c3d2724..ed0e9686f8 100644 --- a/meson.build +++ b/meson.build @@ -1635,15 +1635,17 @@ endif if not get_option('driver_network').disabled() and conf.has('WITH_LIBVIRTD') conf.set('WITH_NETWORK', 1) - firewall_backend_default_1 = get_option('firewall_backend_default_1') - firewall_backend_default_conf = firewall_backend_default_1 - firewall_backend_default_1 = 'VIR_FIREWALL_BACKEND_' + firewall_backend_default_1.to_upper() - conf.set('FIREWALL_BACKEND_DEFAULT_1', firewall_backend_default_1) - firewall_backend_default_2 = get_option('firewall_backend_default_2') - firewall_backend_default_2 = 'VIR_FIREWALL_BACKEND_' + firewall_backend_default_2.to_upper() - conf.set('FIREWALL_BACKEND_DEFAULT_2', firewall_backend_default_2) + 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') + 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()) 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 ad354a8668..8723d13231 100644 --- a/meson_options.txt +++ b/meson_options.txt @@ -115,8 +115,7 @@ 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_default_1', type: 'string', value: 'nftables', description: 'first firewall backend to try when none is specified') -option('firewall_backend_default_2', type: 'string', value: 'iptables', description: 'second firewall backend to try when none is specified (and first is unavailable)') +option('firewall_backend_priority', type: 'array', choices: ['nftables', 'iptables'], description: 'firewall backends to try, preferred ones first') 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 8f4956dace..e2f3613a41 100644 --- a/src/network/bridge_driver_conf.c +++ b/src/network/bridge_driver_conf.c @@ -67,8 +67,12 @@ virNetworkLoadDriverConfig(virNetworkDriverConfig *cfg G_GNUC_UNUSED, g_autofree char *fwBackendStr = NULL; bool fwBackendSelected = false; size_t i; - int fwBackends[] = { FIREWALL_BACKEND_DEFAULT_1, FIREWALL_BACKEND_DEFAULT_2 }; + int fwBackends[] = { + FIREWALL_BACKEND_PRIORITY_0, + FIREWALL_BACKEND_PRIORITY_1, + }; G_STATIC_ASSERT(G_N_ELEMENTS(fwBackends) == VIR_FIREWALL_BACKEND_LAST); + G_STATIC_ASSERT(G_N_ELEMENTS(fwBackends) == FIREWALL_BACKEND_PRIORITY_NUM); int nFwBackends = G_N_ELEMENTS(fwBackends); if (access(filename, R_OK) == 0) { diff --git a/src/network/meson.build b/src/network/meson.build index bf2893accc..07cd5cda55 100644 --- a/src/network/meson.build +++ b/src/network/meson.build @@ -51,7 +51,8 @@ if conf.has('WITH_NETWORK') } network_options_conf = configuration_data({ - 'FIREWALL_BACKEND': firewall_backend_default_conf, + 'FIREWALL_BACKEND_PRIORITY': ', '.join(firewall_backend_priority), + 'FIREWALL_BACKEND': firewall_backend_priority[0], }) network_conf = configure_file( @@ -61,7 +62,8 @@ if conf.has('WITH_NETWORK') ) network_options_hack_conf = configuration_data({ - 'FIREWALL_BACKEND': firewall_backend_default_conf, + 'FIREWALL_BACKEND_PRIORITY': ', '.join(firewall_backend_priority), + 'FIREWALL_BACKEND': firewall_backend_priority[0], # This hack is necessary because the output file is going to be # used as input for another configure_file() call later, which # will take care of substituting @CONFIG@ with useful data diff --git a/src/network/network.conf.in b/src/network/network.conf.in index f579f39fcd..5ed64a04a5 100644 --- a/src/network/network.conf.in +++ b/src/network/network.conf.in @@ -12,12 +12,13 @@ # iptables - use iptables commands to construct the firewall # nftables - use nft commands to construct the firewall # -# If firewall_backend isn't set in this file, libvirt will -# prefer the @FIREWALL_BACKEND@ backend *if the necessary package. -# binary is installed*, otherwise it will look for the package/binary -# needed for the other backend and use that if available. If neither -# is available on the host, then the network driver will fail to -# start, and an error will be logged. +# If firewall_backend isn't configured, libvirt will choose the +# first available backend from the following list: +# +# [@FIREWALL_BACKEND_PRIORITY@] +# +# If no backend is available on the host, then the network driver +# will fail to start, and an error will be logged. # # (NB: switching from one backend to another while there are active # virtual networks *is* supported. The change will take place the -- 2.45.1

On 5/28/24 12:31 PM, Pavel Hrdina wrote: But we don't just need to check that the values in the list are all valid options; we also want to make sure that nobody has entered the same value multiple times (which this ends up doing by making sure that there is at least one entry for each valid value, and that the list is the same length as the number of valid values). Or do we not care if someone repeats the same value? Maybe somebody wants to include iptables support in the build, but not look for it automatically (instead only use it if it's explicitly requested in network.conf). One way of doing that would be to sent firewall_backend_priority = nftables,nftables (that does seem a bit obtuse; perhaps it would be better to allow limiting the length of the option list to 1) Anyway, I'm fine with it either way. Both are better than what I had before.

On 5/28/24 11:49 AM, Andrea Bolognani wrote: Okay, yeah. That does actually make sure that both possibilities are in the list, and (indirectly) that none is duplicated. Yes! This is the way I initially wanted to do it, but didn't have enough meson-foo to make it work. I had to think about this for a minute, since at first glance those both seem kind of the same. you want to continue checking that the backends priority list has an entry for every item, and also make sure that there wasn't an extra item in the priorities list given to the build.

On Mon, Jun 03, 2024 at 10:57:15AM GMT, Daniel P. Berrangé wrote: You're right. I'll fix it. Unfortunately 10.4.0 has already been tagged :( -- Andrea Bolognani / Red Hat / Virtualization