From c19df00f6def1ee74ae0812b529f2a1b589c256f Mon Sep 17 00:00:00 2001

From: Daniel Wang <wonderfly@users.noreply.github.com>

Date: Sat, 20 May 2017 04:05:18 -0700

Subject: [PATCH] DHCP: when adding static routes set scopes properly (#5982)

DHCP responses could include static routes, but unfortunately not an

option to tell what scope to use. So it's important that the client sets

it properly.

This mimics what the `ip route add` command does when adding a static

route without an explicit scope:

* If the destination IP is on the local host, use scope `host`

* Otherwise if the gateway IP is null (direct route), use scope `link`

* If anything else, use the current default `global`.

Fixes #5979.

(cherry picked from commit d6eac9bd06066c8d041449538a9cdee0fd928835)

---

 man/systemd.network.xml      |  8 +++++---

 src/network/networkd-dhcp4.c | 17 +++++++++++++++--

 2 files changed, 20 insertions(+), 5 deletions(-)

diff --git a/man/systemd.network.xml b/man/systemd.network.xml

index b807ebf29b..aaa7b0968d 100644

--- a/man/systemd.network.xml

+++ b/man/systemd.network.xml

@@ -937,9 +937,11 @@

         <varlistentry>

           <term><varname>UseRoutes=</varname></term>

           <listitem>

-            <para>When true (the default), the static routes will be

-            requested from the DHCP server and added to the routing

-            table with a metric of 1024.</para>

+            <para>When true (the default), the static routes will be requested from the DHCP server and added to the

+              routing table with a metric of 1024, and a scope of "global", "link" or "host", depending on the route's

+              destination and gateway. If the destination is on the local host, e.g., 127.x.x.x, or the same as the

+              link's own address, the scope will be set to "host". Otherwise if the gateway is null (a direct route), a

+              "link" scope will be used. For anything else, scope defaults to "global".</para>

           </listitem>

         </varlistentry>

diff --git a/src/network/networkd-dhcp4.c b/src/network/networkd-dhcp4.c

index c5c5b95c8f..ae0f78daab 100644

--- a/src/network/networkd-dhcp4.c

+++ b/src/network/networkd-dhcp4.c

@@ -52,8 +52,21 @@ static int dhcp4_route_handler(sd_netlink *rtnl, sd_netlink_message *m,

         return 1;

 }

+static int route_scope_from_address(const Route *route, const struct in_addr *self_addr) {

+        assert(route);

+        assert(self_addr);

+

+        if (in_addr_is_localhost(AF_INET, &route->dst) ||

+            (self_addr->s_addr && route->dst.in.s_addr == self_addr->s_addr))

+                return RT_SCOPE_HOST;

+        else if (in4_addr_is_null(&route->gw.in))

+                return RT_SCOPE_LINK;

+        else

+                return RT_SCOPE_UNIVERSE;

+}

+

 static int link_set_dhcp_routes(Link *link) {

-        struct in_addr gateway;

+        struct in_addr gateway, address;

         _cleanup_free_ sd_dhcp_route **static_routes = NULL;

         int r, n, i;

@@ -69,7 +82,6 @@ static int link_set_dhcp_routes(Link *link) {

                 return log_link_warning_errno(link, r, "DHCP error: could not get gateway: %m");

         if (r >= 0) {

-                struct in_addr address;

                 _cleanup_route_free_ Route *route = NULL;

                 _cleanup_route_free_ Route *route_gw = NULL;

@@ -141,6 +153,7 @@ static int link_set_dhcp_routes(Link *link) {

                 assert_se(sd_dhcp_route_get_destination_prefix_length(static_routes[i], &route->dst_prefixlen) >= 0);

                 route->priority = link->network->dhcp_route_metric;

                 route->table = link->network->dhcp_route_table;

+                route->scope = route_scope_from_address(route, &address);

                 r = route_configure(route, link, dhcp4_route_handler);

                 if (r < 0)