route-table: Retrieving the preferred source address from Netlink.

We can use the "ip route add ... src ..." command to set the preferred
source address for each entry in the kernel FIB. OVS has a mechanism to
cache the FIB, but the preferred source address is ignored and
calculated with its own logic. This patch resolves the difference
between kernel FIB and OVS route table cache by retrieving the
RTA_PREFSRC attribute of Netlink messages.

Acked-by: Eelco Chaudron <echaudro@redhat.com>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Signed-off-by: Nobuhiro MIKI <nmiki@yahoo-corp.jp>
Signed-off-by: Ilya Maximets <i.maximets@ovn.org>

3 files changed, 20 insertions, 5 deletions

diff --git a/lib/ovs-router.c b/lib/ovs-router.c
index 3107f2d56..7c04bb0e6 100644
--- a/lib/ovs-router.c
+++ b/lib/ovs-router.c
@@ -319,13 +319,13 @@ ovs_router_insert__(uint32_t mark, uint8_t priority, bool local,
 
 void
 ovs_router_insert(uint32_t mark, const struct in6_addr *ip_dst, uint8_t plen,
-                  bool local, const char output_bridge[], 
-                  const struct in6_addr *gw)
+                  bool local, const char output_bridge[],
+                  const struct in6_addr *gw, const struct in6_addr *prefsrc)
 {
     if (use_system_routing_table) {
         uint8_t priority = local ? plen + 64 : plen;
         ovs_router_insert__(mark, priority, local, ip_dst, plen,
-                            output_bridge, gw, &in6addr_any);
+                            output_bridge, gw, prefsrc);
     }
 }
 
diff --git a/lib/ovs-router.h b/lib/ovs-router.h
index d8ce3c00d..eb4ff85d9 100644
--- a/lib/ovs-router.h
+++ b/lib/ovs-router.h
@@ -32,7 +32,8 @@ bool ovs_router_lookup(uint32_t mark, const struct in6_addr *ip_dst,
 void ovs_router_init(void);
 void ovs_router_insert(uint32_t mark, const struct in6_addr *ip_dst,
                        uint8_t plen, bool local,
-                       const char output_bridge[], const struct in6_addr *gw);
+                       const char output_bridge[], const struct in6_addr *gw,
+                       const struct in6_addr *prefsrc);
 void ovs_router_flush(void);
 
 void ovs_router_disable_system_routing_table(void);
diff --git a/lib/route-table.c b/lib/route-table.c
index ac82cf262..9927dcc18 100644
--- a/lib/route-table.c
+++ b/lib/route-table.c
@@ -51,6 +51,7 @@ struct route_data {
 
     /* Extracted from Netlink attributes. */
     struct in6_addr rta_dst; /* 0 if missing. */
+    struct in6_addr rta_prefsrc; /* 0 if missing. */
     struct in6_addr rta_gw;
     char ifname[IFNAMSIZ]; /* Interface name. */
     uint32_t mark;
@@ -201,6 +202,7 @@ route_table_parse(struct ofpbuf *buf, struct route_table_msg *change)
         [RTA_OIF] = { .type = NL_A_U32, .optional = true },
         [RTA_GATEWAY] = { .type = NL_A_U32, .optional = true },
         [RTA_MARK] = { .type = NL_A_U32, .optional = true },
+        [RTA_PREFSRC] = { .type = NL_A_U32, .optional = true },
     };
 
     static const struct nl_policy policy6[] = {
@@ -208,6 +210,7 @@ route_table_parse(struct ofpbuf *buf, struct route_table_msg *change)
         [RTA_OIF] = { .type = NL_A_U32, .optional = true },
         [RTA_MARK] = { .type = NL_A_U32, .optional = true },
         [RTA_GATEWAY] = { .type = NL_A_IPV6, .optional = true },
+        [RTA_PREFSRC] = { .type = NL_A_IPV6, .optional = true },
     };
 
     struct nlattr *attrs[ARRAY_SIZE(policy)];
@@ -274,6 +277,16 @@ route_table_parse(struct ofpbuf *buf, struct route_table_msg *change)
         } else if (ipv4) {
             in6_addr_set_mapped_ipv4(&change->rd.rta_dst, 0);
         }
+        if (attrs[RTA_PREFSRC]) {
+            if (ipv4) {
+                ovs_be32 prefsrc;
+                prefsrc = nl_attr_get_be32(attrs[RTA_PREFSRC]);
+                in6_addr_set_mapped_ipv4(&change->rd.rta_prefsrc, prefsrc);
+            } else {
+                change->rd.rta_prefsrc =
+                    nl_attr_get_in6_addr(attrs[RTA_PREFSRC]);
+            }
+        }
         if (attrs[RTA_GATEWAY]) {
             if (ipv4) {
                 ovs_be32 gw;
@@ -309,7 +322,8 @@ route_table_handle_msg(const struct route_table_msg *change)
         const struct route_data *rd = &change->rd;
 
         ovs_router_insert(rd->mark, &rd->rta_dst, rd->rtm_dst_len,
-                          rd->local, rd->ifname, &rd->rta_gw);
+                          rd->local, rd->ifname, &rd->rta_gw,
+                          &rd->rta_prefsrc);
     }
 }