network: ndisc: introduce UseGateway= and UseRoutePrefix= settings

Closes #21263.

man/systemd.network.xml

@@ -2295,6 +2295,22 @@ Token=prefixstable:2002:da8:1::</programlisting></para>
           </listitem>
         </varlistentry>
 
+        <varlistentry>
+          <term><varname>UseGateway=</varname></term>
+          <listitem>
+            <para>When true (the default), the router address will be configured as the default gateway.
+            </para>
+          </listitem>
+        </varlistentry>
+
+        <varlistentry>
+          <term><varname>UseRoutePrefix=</varname></term>
+          <listitem>
+            <para>When true (the default), the routes corresponding to the route prefixes received in
+            the Router Advertisement will be configured.</para>
+          </listitem>
+        </varlistentry>
+
         <varlistentry>
           <term><varname>UseAutonomousPrefix=</varname></term>
           <listitem>

src/network/networkd-ndisc.c

@@ -290,7 +290,6 @@ static int ndisc_request_address(Address *in, Link *link, sd_ndisc_router *rt) {
 }
 
 static int ndisc_router_process_default(Link *link, sd_ndisc_router *rt) {
-        _cleanup_(route_freep) Route *route = NULL;
         usec_t lifetime_usec, timestamp_usec;
         struct in6_addr gateway;
         uint16_t lifetime_sec;
@@ -299,8 +298,13 @@ static int ndisc_router_process_default(Link *link, sd_ndisc_router *rt) {
         int r;
 
         assert(link);
+        assert(link->network);
         assert(rt);
 
+        if (!link->network->ipv6_accept_ra_use_gateway &&
+            hashmap_isempty(link->network->routes_by_section))
+                return 0;
+
         r = sd_ndisc_router_get_lifetime(rt, &lifetime_sec);
         if (r < 0)
                 return log_link_error_errno(link, r, "Failed to get gateway lifetime from RA: %m");
@@ -339,23 +343,29 @@ static int ndisc_router_process_default(Link *link, sd_ndisc_router *rt) {
                         return log_link_error_errno(link, r, "Failed to get default router MTU from RA: %m");
         }
 
-        r = route_new(&route);
+        if (link->network->ipv6_accept_ra_use_gateway) {
-        if (r < 0)
+                _cleanup_(route_freep) Route *route = NULL;
-                return log_oom();
 
-        route->family = AF_INET6;
+                r = route_new(&route);
-        route->pref = preference;
+                if (r < 0)
-        route->gw_family = AF_INET6;
+                        return log_oom();
-        route->gw.in6 = gateway;
-        route->lifetime_usec = lifetime_usec;
-        route->mtu = mtu;
 
-        r = ndisc_request_route(TAKE_PTR(route), link, rt);
+                route->family = AF_INET6;
-        if (r < 0)
+                route->pref = preference;
-                return log_link_error_errno(link, r, "Could not request default route: %m");
+                route->gw_family = AF_INET6;
+                route->gw.in6 = gateway;
+                route->lifetime_usec = lifetime_usec;
+                route->mtu = mtu;
+
+                r = ndisc_request_route(TAKE_PTR(route), link, rt);
+                if (r < 0)
+                        return log_link_error_errno(link, r, "Could not request default route: %m");
+        }
 
         Route *route_gw;
         HASHMAP_FOREACH(route_gw, link->network->routes_by_section) {
+                _cleanup_(route_freep) Route *route = NULL;
+
                 if (!route_gw->gateway_from_dhcp_or_ra)
                         continue;
 
@@ -584,6 +594,9 @@ static int ndisc_router_process_route(Link *link, sd_ndisc_router *rt) {
 
         assert(link);
 
+        if (!link->network->ipv6_accept_ra_use_route_prefix)
+                return 0;
+
         r = sd_ndisc_router_route_get_lifetime(rt, &lifetime_sec);
         if (r < 0)
                 return log_link_error_errno(link, r, "Failed to get route lifetime from RA: %m");

src/network/networkd-network-gperf.gperf

@@ -255,6 +255,8 @@ DHCPv6.IAID,                                 config_parse_iaid,
 DHCPv6.DUIDType,                             config_parse_duid_type,                                   0,                             offsetof(Network, dhcp6_duid)
 DHCPv6.DUIDRawData,                          config_parse_duid_rawdata,                                0,                             offsetof(Network, dhcp6_duid)
 DHCPv6.RouteTable,                           config_parse_dhcp_or_ra_route_table,                      (RTPROT_DHCP<<16) | AF_INET6,  0
+IPv6AcceptRA.UseGateway,                     config_parse_bool,                                        0,                             offsetof(Network, ipv6_accept_ra_use_gateway)
+IPv6AcceptRA.UseRoutePrefix,                 config_parse_bool,                                        0,                             offsetof(Network, ipv6_accept_ra_use_route_prefix)
 IPv6AcceptRA.UseAutonomousPrefix,            config_parse_bool,                                        0,                             offsetof(Network, ipv6_accept_ra_use_autonomous_prefix)
 IPv6AcceptRA.UseOnLinkPrefix,                config_parse_bool,                                        0,                             offsetof(Network, ipv6_accept_ra_use_onlink_prefix)
 IPv6AcceptRA.UseDNS,                         config_parse_bool,                                        0,                             offsetof(Network, ipv6_accept_ra_use_dns)

src/network/networkd-network.c

@@ -464,6 +464,8 @@ int network_load_one(Manager *manager, OrderedHashmap **networks, const char *fi
 
                 .ipv6_accept_ra = -1,
                 .ipv6_accept_ra_use_dns = true,
+                .ipv6_accept_ra_use_gateway = true,
+                .ipv6_accept_ra_use_route_prefix = true,
                 .ipv6_accept_ra_use_autonomous_prefix = true,
                 .ipv6_accept_ra_use_onlink_prefix = true,
                 .ipv6_accept_ra_use_mtu = true,

src/network/networkd-network.h

@@ -301,6 +301,8 @@ struct Network {
         /* IPv6 accept RA */
         int ipv6_accept_ra;
         bool ipv6_accept_ra_use_dns;
+        bool ipv6_accept_ra_use_gateway;
+        bool ipv6_accept_ra_use_route_prefix;
         bool ipv6_accept_ra_use_autonomous_prefix;
         bool ipv6_accept_ra_use_onlink_prefix;
         bool ipv6_accept_ra_use_mtu;

test/fuzz/fuzz-network-parser/directives.network

@@ -352,6 +352,8 @@ RouteTable=
 RouteMetric=
 UseDNS=
 DHCPv6Client=
+UseGateway=
+UseRoutePrefix=
 UseAutonomousPrefix=
 UseOnLinkPrefix=
 RouterAllowList=