nat: T538: Add static NAT one-to-one

Ability to set static NAT (one-to-one) in one rule

set nat static rule 10 destination address '203.0.113.0/24'
set nat static rule 10 inbound-interface 'eth0'
set nat static rule 10 translation address '192.0.2.0/24'

It will be enough for PREROUTING and POSTROUTING rules
Use a separate table 'vyos_static_nat' as SRC/DST rules and
STATIC rules can have the same rule number

2 files changed, 135 insertions, 0 deletions

diff --git a/data/templates/firewall/nftables-static-nat.j2 b/data/templates/firewall/nftables-static-nat.j2
new file mode 100644
index 000000000..d3c43858f
--- /dev/null
+++ b/data/templates/firewall/nftables-static-nat.j2
@@ -0,0 +1,115 @@
+#!/usr/sbin/nft -f
+
+{% macro nat_rule(rule, config, chain) %}
+{% set comment  = '' %}
+{% set base_log = '' %}
+
+{% if chain is vyos_defined('PREROUTING') %}
+{%     set comment   = 'STATIC-NAT-' ~ rule %}
+{%     set base_log  = '[NAT-DST-' ~ rule %}
+{%     set interface = ' iifname "' ~ config.inbound_interface ~ '"' if config.inbound_interface is vyos_defined and config.inbound_interface is not vyos_defined('any') else '' %}
+{%     if config.translation.address is vyos_defined %}
+{#         support 1:1 network translation #}
+{%         if config.translation.address | is_ip_network %}
+{%             set trns_addr = 'dnat ip prefix to ip daddr map { ' ~ config.destination.address ~ ' : ' ~ config.translation.address ~ ' }' %}
+{#             we can now clear out the dst_addr part as it's already covered in aboves map #}
+{%         else %}
+{%             set dst_addr  = 'ip daddr ' ~ config.destination.address if config.destination.address is vyos_defined %}
+{%             set trns_addr = 'dnat to ' ~ config.translation.address %}
+{%         endif %}
+{%     endif %}
+{% elif chain is vyos_defined('POSTROUTING') %}
+{%     set comment   = 'STATIC-NAT-' ~ rule %}
+{%     set base_log  = '[NAT-SRC-' ~ rule %}
+{%     set interface = ' oifname "' ~ config.inbound_interface ~ '"' if config.inbound_interface is vyos_defined and config.inbound_interface is not vyos_defined('any') else '' %}
+{%     if config.translation.address is vyos_defined %}
+{#         support 1:1 network translation #}
+{%         if config.translation.address | is_ip_network %}
+{%             set trns_addr = 'snat ip prefix to ip saddr map { ' ~ config.translation.address ~ ' : ' ~ config.destination.address ~ ' }' %}
+{#             we can now clear out the src_addr part as it's already covered in aboves map #}
+{%         else %}
+{%             set src_addr  = 'ip saddr ' ~ config.translation.address if config.translation.address is vyos_defined %}
+{%             set trns_addr = 'snat to ' ~ config.destination.address %}
+{%         endif %}
+{%     endif %}
+{% endif %}
+
+{% if config.exclude is vyos_defined %}
+{#     rule has been marked as 'exclude' thus we simply return here #}
+{%     set trns_addr = 'return' %}
+{%     set trns_port = '' %}
+{% endif %}
+
+{% if config.translation.options is vyos_defined %}
+{%     if config.translation.options.address_mapping is vyos_defined('persistent') %}
+{%         set trns_opts_addr  = 'persistent' %}
+{%     endif %}
+{%     if config.translation.options.port_mapping is vyos_defined('random') %}
+{%         set trns_opts_port  = 'random' %}
+{%     elif config.translation.options.port_mapping is vyos_defined('fully-random') %}
+{%         set trns_opts_port  = 'fully-random' %}
+{%     endif %}
+{% endif %}
+
+{% if trns_opts_addr is vyos_defined and trns_opts_port is vyos_defined %}
+{%     set trns_opts  = trns_opts_addr ~ ',' ~ trns_opts_port %}
+{% elif trns_opts_addr is vyos_defined %}
+{%     set trns_opts  = trns_opts_addr %}
+{% elif trns_opts_port is vyos_defined %}
+{%     set trns_opts  = trns_opts_port %}
+{% endif %}
+
+{% set output = 'add rule ip vyos_static_nat ' ~ chain ~ interface %}
+
+{% if dst_addr is vyos_defined %}
+{%     set output = output ~ ' ' ~ dst_addr %}
+{% endif %}
+{% if src_addr is vyos_defined %}
+{%     set output = output ~ ' ' ~ src_addr %}
+{% endif %}
+
+{# Count packets #}
+{% set output = output ~ ' counter' %}
+{# Special handling of log option, we must repeat the entire rule before the #}
+{# NAT translation options are added, this is essential                      #}
+{% if log is vyos_defined %}
+{%     set log_output = output ~ ' log prefix "' ~ log ~ '" comment "' ~ comment ~ '"' %}
+{% endif %}
+{% if trns_addr is vyos_defined %}
+{%     set output = output ~ ' ' ~ trns_addr %}
+{% endif %}
+
+{% if trns_opts is vyos_defined %}
+{%     set output = output ~ ' ' ~ trns_opts %}
+{% endif %}
+{% if comment is vyos_defined %}
+{%     set output = output ~ ' comment "' ~ comment ~ '"' %}
+{% endif %}
+{{ log_output if log_output is vyos_defined }}
+{{ output }}
+{% endmacro %}
+
+# Start with clean STATIC NAT chains
+flush chain ip vyos_static_nat PREROUTING
+flush chain ip vyos_static_nat POSTROUTING
+
+{# NAT if enabled - add targets to nftables #}
+
+#
+# Destination NAT rules build up here
+#
+add rule ip vyos_static_nat PREROUTING counter jump VYOS_PRE_DNAT_HOOK
+{% if static.rule is vyos_defined %}
+{%     for rule, config in static.rule.items() if config.disable is not vyos_defined %}
+{{ nat_rule(rule, config, 'PREROUTING') }}
+{%     endfor %}
+{% endif %}
+#
+# Source NAT rules build up here
+#
+add rule ip vyos_static_nat POSTROUTING counter jump VYOS_PRE_SNAT_HOOK
+{% if static.rule is vyos_defined %}
+{%     for rule, config in static.rule.items() if config.disable is not vyos_defined %}
+{{ nat_rule(rule, config, 'POSTROUTING') }}
+{%     endfor %}
+{% endif %}
diff --git a/data/templates/firewall/nftables.j2 b/data/templates/firewall/nftables.j2
index b91fed615..5971e1bbc 100644
--- a/data/templates/firewall/nftables.j2
+++ b/data/templates/firewall/nftables.j2
@@ -181,6 +181,26 @@ table ip nat {
     }
 }
 
+table ip vyos_static_nat {
+    chain PREROUTING {
+        type nat hook prerouting priority -100; policy accept;
+        counter jump VYOS_PRE_DNAT_HOOK
+    }
+
+    chain POSTROUTING {
+        type nat hook postrouting priority 100; policy accept;
+        counter jump VYOS_PRE_SNAT_HOOK
+    }
+
+    chain VYOS_PRE_DNAT_HOOK {
+        return
+    }
+
+    chain VYOS_PRE_SNAT_HOOK {
+        return
+    }
+}
+
 table ip6 nat {
     chain PREROUTING {
         type nat hook prerouting priority -100; policy accept;