network: adjust route priority based on preference

Even if different preference is specified, the kernel merges multiple
routes with the same preference. This is problematic when a network has
multiple routers.

Fixes #25138.

1 files changed, 65 insertions, 8 deletions

diff --git a/src/network/networkd-dhcp-common.c b/src/network/networkd-dhcp-common.c
index 6526d3378f..2a80b1766e 100644
--- a/src/network/networkd-dhcp-common.c
+++ b/src/network/networkd-dhcp-common.c
@@ -303,7 +303,7 @@ int config_parse_dhcp(
         return 0;
 }
 
-int config_parse_dhcp_or_ra_route_metric(
+int config_parse_dhcp_route_metric(
                 const char* unit,
                 const char *filename,
                 unsigned line,
@@ -321,7 +321,7 @@ int config_parse_dhcp_or_ra_route_metric(
 
         assert(filename);
         assert(lvalue);
-        assert(IN_SET(ltype, AF_UNSPEC, AF_INET, AF_INET6));
+        assert(IN_SET(ltype, AF_UNSPEC, AF_INET));
         assert(rvalue);
         assert(data);
 
@@ -337,16 +337,15 @@ int config_parse_dhcp_or_ra_route_metric(
                 network->dhcp_route_metric = metric;
                 network->dhcp_route_metric_set = true;
                 break;
-        case AF_INET6:
-                network->ipv6_accept_ra_route_metric = metric;
-                network->ipv6_accept_ra_route_metric_set = true;
-                break;
         case AF_UNSPEC:
                 /* For backward compatibility. */
                 if (!network->dhcp_route_metric_set)
                         network->dhcp_route_metric = metric;
-                if (!network->ipv6_accept_ra_route_metric_set)
-                        network->ipv6_accept_ra_route_metric = metric;
+                if (!network->ipv6_accept_ra_route_metric_set) {
+                        network->ipv6_accept_ra_route_metric_high = metric;
+                        network->ipv6_accept_ra_route_metric_medium = metric;
+                        network->ipv6_accept_ra_route_metric_low = metric;
+                }
                 break;
         default:
                 assert_not_reached();
@@ -355,6 +354,64 @@ int config_parse_dhcp_or_ra_route_metric(
         return 0;
 }
 
+int config_parse_ipv6_accept_ra_route_metric(
+                const char *unit,
+                const char *filename,
+                unsigned line,
+                const char *section,
+                unsigned section_line,
+                const char *lvalue,
+                int ltype,
+                const char *rvalue,
+                void *data,
+                void *userdata) {
+
+        Network *network = ASSERT_PTR(userdata);
+        uint32_t metric_high, metric_medium, metric_low;
+        int r, s, t;
+
+        assert(filename);
+        assert(rvalue);
+
+        if (safe_atou32(rvalue, &metric_low) >= 0)
+                metric_high = metric_medium = metric_low;
+        else {
+                _cleanup_free_ char *high = NULL, *medium = NULL, *low = NULL;
+                const char *p = rvalue;
+
+                r = extract_many_words(&p, ":", EXTRACT_DONT_COALESCE_SEPARATORS, &high, &medium, &low, NULL);
+                if (r == -ENOMEM)
+                        return log_oom();
+                if (r != 3 || !isempty(p)) {
+                        log_syntax(unit, LOG_WARNING, filename, line, r < 0 ? r : 0,
+                                   "Failed to parse RouteTable=%s, ignoring assignment: %m", rvalue);
+                        return 0;
+                }
+
+                r = safe_atou32(high, &metric_high);
+                s = safe_atou32(medium, &metric_medium);
+                t = safe_atou32(low, &metric_low);
+                if (r < 0 || s < 0 || t < 0) {
+                        log_syntax(unit, LOG_WARNING, filename, line, r < 0 ? r : s < 0 ? s : t,
+                                   "Failed to parse RouteTable=%s, ignoring assignment: %m", rvalue);
+                        return 0;
+                }
+
+                if (metric_high >= metric_medium || metric_medium >= metric_low) {
+                        log_syntax(unit, LOG_WARNING, filename, line, 0,
+                                   "Invalid RouteTable=%s, ignoring assignment: %m", rvalue);
+                        return 0;
+                }
+        }
+
+        network->ipv6_accept_ra_route_metric_high = metric_high;
+        network->ipv6_accept_ra_route_metric_medium = metric_medium;
+        network->ipv6_accept_ra_route_metric_low = metric_low;
+        network->ipv6_accept_ra_route_metric_set = true;
+
+        return 0;
+}
+
 int config_parse_dhcp_use_dns(
                 const char* unit,
                 const char *filename,