policy: T2199: Refactor policy route script for better error handling

* Migrates all policy route references from `ipv6-route` to `route6`
* Update test config `dialup-router-medium-vpn` to test migration of `ipv6-route` to `route6`

2 files changed, 127 insertions, 50 deletions

diff --git a/src/conf_mode/policy-route-interface.py b/src/conf_mode/policy-route-interface.py
index e81135a74..1108aebe6 100755
--- a/src/conf_mode/policy-route-interface.py
+++ b/src/conf_mode/policy-route-interface.py
@@ -52,7 +52,7 @@ def verify(if_policy):
     if not if_policy:
         return None
 
-    for route in ['route', 'ipv6_route']:
+    for route in ['route', 'route6']:
         if route in if_policy:
             if route not in if_policy['policy']:
                 raise ConfigError('Policy route not configured')
@@ -71,7 +71,7 @@ def cleanup_rule(table, chain, ifname, new_name=None):
     results = cmd(f'nft -a list chain {table} {chain}').split("\n")
     retval = None
     for line in results:
-        if f'oifname "{ifname}"' in line:
+        if f'ifname "{ifname}"' in line:
             if new_name and f'jump {new_name}' in line:
                 # new_name is used to clear rules for any previously referenced chains
                 # returns true when rule exists and doesn't need to be created
@@ -98,8 +98,8 @@ def apply(if_policy):
     else:
         cleanup_rule('ip mangle', route_chain, ifname)
 
-    if 'ipv6_route' in if_policy:
-        name = 'VYOS_PBR6_' + if_policy['ipv6_route']
+    if 'route6' in if_policy:
+        name = 'VYOS_PBR6_' + if_policy['route6']
         rule_exists = cleanup_rule('ip6 mangle', ipv6_route_chain, ifname, name)
 
         if not rule_exists:
diff --git a/src/conf_mode/policy-route.py b/src/conf_mode/policy-route.py
index 9edab4b47..c5904309f 100755
--- a/src/conf_mode/policy-route.py
+++ b/src/conf_mode/policy-route.py
@@ -31,6 +31,35 @@ airbag.enable()
 mark_offset = 0x7FFFFFFF
 nftables_conf = '/run/nftables_policy.conf'
 
+preserve_chains = [
+    'VYOS_PBR_PREROUTING',
+    'VYOS_PBR_POSTROUTING',
+    'VYOS_PBR6_PREROUTING',
+    'VYOS_PBR6_POSTROUTING'
+]
+
+valid_groups = [
+    'address_group',
+    'network_group',
+    'port_group'
+]
+
+def get_policy_interfaces(conf):
+    out = {}
+    interfaces = conf.get_config_dict(['interfaces'], key_mangling=('-', '_'), get_first_key=True,
+                                    no_tag_node_value_mangle=True)
+    def find_interfaces(iftype_conf, output={}, prefix=''):
+        for ifname, if_conf in iftype_conf.items():
+            if 'policy' in if_conf:
+                output[prefix + ifname] = if_conf['policy']
+            for vif in ['vif', 'vif_s', 'vif_c']:
+                if vif in if_conf:
+                    output.update(find_interfaces(if_conf[vif], output, f'{prefix}{ifname}.'))
+        return output
+    for iftype, iftype_conf in interfaces.items():
+        out.update(find_interfaces(iftype_conf))
+    return out
+
 def get_config(config=None):
     if config:
         conf = config
@@ -38,61 +67,117 @@ def get_config(config=None):
         conf = Config()
     base = ['policy']
 
-    if not conf.exists(base + ['route']) and not conf.exists(base + ['ipv6-route']):
-        return None
-
     policy = conf.get_config_dict(base, key_mangling=('-', '_'), get_first_key=True,
                                     no_tag_node_value_mangle=True)
 
+    policy['firewall_group'] = conf.get_config_dict(['firewall', 'group'], key_mangling=('-', '_'), get_first_key=True,
+                                    no_tag_node_value_mangle=True)
+    policy['interfaces'] = get_policy_interfaces(conf)
+
     return policy
 
-def verify(policy):
-    # bail out early - looks like removal from running config
-    if not policy:
-        return None
+def verify_rule(policy, rule_conf, ipv6):
+    icmp = 'icmp' if not ipv6 else 'icmpv6'
+    if icmp in rule_conf:
+        icmp_defined = False
+        if 'type_name' in rule_conf[icmp]:
+            icmp_defined = True
+            if 'code' in rule_conf[icmp] or 'type' in rule_conf[icmp]:
+                raise ConfigError(f'{name} rule {rule_id}: Cannot use ICMP type/code with ICMP type-name')
+        if 'code' in rule_conf[icmp]:
+            icmp_defined = True
+            if 'type' not in rule_conf[icmp]:
+                raise ConfigError(f'{name} rule {rule_id}: ICMP code can only be defined if ICMP type is defined')
+        if 'type' in rule_conf[icmp]:
+            icmp_defined = True
+
+        if icmp_defined and 'protocol' not in rule_conf or rule_conf['protocol'] != icmp:
+            raise ConfigError(f'{name} rule {rule_id}: ICMP type/code or type-name can only be defined if protocol is ICMP')
+    if 'set' in rule_conf:
+        if 'tcp_mss' in rule_conf['set']:
+            tcp_flags = dict_search_args(rule_conf, 'tcp', 'flags')
+            if not tcp_flags or 'SYN' not in tcp_flags.split(","):
+                raise ConfigError(f'{name} rule {rule_id}: TCP SYN flag must be set to modify TCP-MSS')
+    if 'tcp' in rule_conf:
+        if 'flags' in rule_conf['tcp']:
+            if 'protocol' not in rule_conf or rule_conf['protocol'] != 'tcp':
+                raise ConfigError(f'{name} rule {rule_id}: TCP flags can only be set if protocol is set to TCP')
+
+    for side in ['destination', 'source']:
+        if side in rule_conf:
+            side_conf = rule_conf[side]
+
+            if 'group' in side_conf:
+                if {'address_group', 'network_group'} <= set(side_conf['group']):
+                    raise ConfigError('Only one address-group or network-group can be specified')
+
+                for group in valid_groups:
+                    if group in side_conf['group']:
+                        group_name = side_conf['group'][group]
+                        fw_group = f'ipv6_{group}' if ipv6 and group in ['address_group', 'network_group'] else group
+                        error_group = fw_group.replace("_", "-")
+                        group_obj = dict_search_args(policy['firewall_group'], fw_group, group_name)
+
+                        if group_obj is None:
+                            raise ConfigError(f'Invalid {error_group} "{group_name}" on policy route rule')
+
+                        if not group_obj:
+                            print(f'WARNING: {error_group} "{group_name}" has no members')
+
+            if 'port' in side_conf or dict_search_args(side_conf, 'group', 'port_group'):
+                if 'protocol' not in rule_conf:
+                    raise ConfigError('Protocol must be defined if specifying a port or port-group')
+
+                if rule_conf['protocol'] not in ['tcp', 'udp', 'tcp_udp']:
+                    raise ConfigError('Protocol must be tcp, udp, or tcp_udp when specifying a port or port-group')
 
+def verify(policy):
     for route in ['route', 'route6']:
+        ipv6 = route == 'route6'
         if route in policy:
             for name, pol_conf in policy[route].items():
                 if 'rule' in pol_conf:
-                    for rule_id, rule_conf in pol_conf.items():
-                        icmp = 'icmp' if route == 'route' else 'icmpv6'
-                        if icmp in rule_conf:
-                            icmp_defined = False
-                            if 'type_name' in rule_conf[icmp]:
-                                icmp_defined = True
-                                if 'code' in rule_conf[icmp] or 'type' in rule_conf[icmp]:
-                                    raise ConfigError(f'{name} rule {rule_id}: Cannot use ICMP type/code with ICMP type-name')
-                            if 'code' in rule_conf[icmp]:
-                                icmp_defined = True
-                                if 'type' not in rule_conf[icmp]:
-                                    raise ConfigError(f'{name} rule {rule_id}: ICMP code can only be defined if ICMP type is defined')
-                            if 'type' in rule_conf[icmp]:
-                                icmp_defined = True
-
-                            if icmp_defined and 'protocol' not in rule_conf or rule_conf['protocol'] != icmp:
-                                raise ConfigError(f'{name} rule {rule_id}: ICMP type/code or type-name can only be defined if protocol is ICMP')
-                        if 'set' in rule_conf:
-                            if 'tcp_mss' in rule_conf['set']:
-                                tcp_flags = dict_search_args(rule_conf, 'tcp', 'flags')
-                                if not tcp_flags or 'SYN' not in tcp_flags.split(","):
-                                    raise ConfigError(f'{name} rule {rule_id}: TCP SYN flag must be set to modify TCP-MSS')
-                        if 'tcp' in rule_conf:
-                            if 'flags' in rule_conf['tcp']:
-                                if 'protocol' not in rule_conf or rule_conf['protocol'] != 'tcp':
-                                    raise ConfigError(f'{name} rule {rule_id}: TCP flags can only be set if protocol is set to TCP')
+                    for rule_id, rule_conf in pol_conf['rule'].items():
+                        verify_rule(policy, rule_conf, ipv6)
+
+    for ifname, if_policy in policy['interfaces'].items():
+        name = dict_search_args(if_policy, 'route')
+        ipv6_name = dict_search_args(if_policy, 'route6')
 
+        if name and not dict_search_args(policy, 'route', name):
+            raise ConfigError(f'Policy route "{name}" is still referenced on interface {ifname}')
+
+        if ipv6_name and not dict_search_args(policy, 'route6', ipv6_name):
+            raise ConfigError(f'Policy route6 "{ipv6_name}" is still referenced on interface {ifname}')
 
     return None
 
-def generate(policy):
-    if not policy:
-        if os.path.exists(nftables_conf):
-            os.unlink(nftables_conf)
-        return None
+def cleanup_commands(policy):
+    commands = []
+    for table in ['ip mangle', 'ip6 mangle']:
+        json_str = cmd(f'nft -j list table {table}')
+        obj = loads(json_str)
+        if 'nftables' not in obj:
+            continue
+        for item in obj['nftables']:
+            if 'chain' in item:
+                chain = item['chain']['name']
+                if not chain.startswith("VYOS_PBR"):
+                    continue
+                if chain not in preserve_chains:
+                    if table == 'ip mangle' and dict_search_args(policy, 'route', chain.replace("VYOS_PBR_", "", 1)):
+                        commands.append(f'flush chain {table} {chain}')
+                    elif table == 'ip6 mangle' and dict_search_args(policy, 'route6', chain.replace("VYOS_PBR6_", "", 1)):
+                        commands.append(f'flush chain {table} {chain}')
+                    else:
+                        commands.append(f'delete chain {table} {chain}')
+    return commands
 
+def generate(policy):
     if not os.path.exists(nftables_conf):
         policy['first_install'] = True
+    else:
+        policy['cleanup_commands'] = cleanup_commands(policy)
 
     render(nftables_conf, 'firewall/nftables-policy.tmpl', policy)
     return None
@@ -124,14 +209,6 @@ def cleanup_table_marks():
             cmd(f'ip rule del fwmark {fwmark} table {table}')
 
 def apply(policy):
-    if not policy or 'first_install' not in policy:
-        run(f'nft flush table ip mangle')
-        run(f'nft flush table ip6 mangle')
-
-    if not policy:
-        cleanup_table_marks()
-        return None
-
     install_result = run(f'nft -f {nftables_conf}')
     if install_result == 1:
         raise ConfigError('Failed to apply policy based routing')