route-table: Support parsing RTA_VIA attribute.

It is possible to add routes for IPv4 destinations using an IPv6 address for next hop. In such configurations the next hop information is provided in the RTA_VIA attribute instead of the RTA_GATEWAY attribute. Signed-off-by: Frode Nordahl <[email protected]> Signed-off-by: 0-day Robot <[email protected]>
ovsrobot · Jan 13, 2025 · 4ae83e8 · 4ae83e8
1 parent 7726fc4
commit 4ae83e8
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diff --git a/lib/netlink.c b/lib/netlink.c
@@ -29,6 +29,16 @@
 #include "openvswitch/vlog.h"
 #include "util.h"
 
+#ifdef HAVE_NETLINK
+#include <linux/rtnetlink.h>
+#else
+/* RTA_VIA */
+struct rtvia {
+    sa_family_t    rtvia_family;
+    uint8_t        rtvia_addr[];
+};
+#endif
+
 VLOG_DEFINE_THIS_MODULE(netlink);
 
 /* A single (bad) Netlink message can in theory dump out many, many log
@@ -819,6 +829,7 @@ min_attr_len(enum nl_attr_type type)
     case NL_A_IPV6: return 16;
     case NL_A_NESTED: return 0;
     case NL_A_LL_ADDR: return 6; /* ETH_ALEN */
+    case NL_A_RTA_VIA: return sizeof(struct rtvia) + sizeof(struct in_addr);
     case N_NL_ATTR_TYPES: default: OVS_NOT_REACHED();
     }
 }
@@ -840,6 +851,7 @@ max_attr_len(enum nl_attr_type type)
     case NL_A_IPV6: return 16;
     case NL_A_NESTED: return SIZE_MAX;
     case NL_A_LL_ADDR: return 20; /* INFINIBAND_ALEN */
+    case NL_A_RTA_VIA: return sizeof(struct rtvia) + sizeof(struct in6_addr);
     case N_NL_ATTR_TYPES: default: OVS_NOT_REACHED();
     }
 }

diff --git a/lib/netlink.h b/lib/netlink.h
@@ -152,6 +152,7 @@ enum nl_attr_type
     NL_A_IPV6,
     NL_A_NESTED,
     NL_A_LL_ADDR,
+    NL_A_RTA_VIA,
     N_NL_ATTR_TYPES
 };
 

diff --git a/lib/route-table.c b/lib/route-table.c
@@ -51,6 +51,7 @@ COVERAGE_DEFINE(route_table_dump);
 struct route_data_nexthop {
     struct ovs_list nexthop_node;
 
+    sa_family_t family;
     struct in6_addr addr;
     char ifname[IFNAMSIZ]; /* Interface name. */
 };
@@ -276,6 +277,7 @@ route_table_parse__(struct ofpbuf *buf, size_t ofs,
         [RTA_PREFSRC] = { .type = NL_A_U32, .optional = true },
         [RTA_TABLE] = { .type = NL_A_U32, .optional = true },
         [RTA_PRIORITY] = { .type = NL_A_U32, .optional = true },
+        [RTA_VIA] = { .type = NL_A_RTA_VIA, .optional = true },
     };
 
     static const struct nl_policy policy6[] = {
@@ -286,6 +288,7 @@ route_table_parse__(struct ofpbuf *buf, size_t ofs,
         [RTA_PREFSRC] = { .type = NL_A_IPV6, .optional = true },
         [RTA_TABLE] = { .type = NL_A_U32, .optional = true },
         [RTA_PRIORITY] = { .type = NL_A_U32, .optional = true },
+        [RTA_VIA] = { .type = NL_A_RTA_VIA, .optional = true },
     };
 
     struct nlattr *attrs[ARRAY_SIZE(policy)];
@@ -310,6 +313,7 @@ route_table_parse__(struct ofpbuf *buf, size_t ofs,
 
         ovs_list_init(&change->rd.nexthops);
         rdnh = &change->rd._primary_next_hop;
+        rdnh->family = rtm->rtm_family;
         ovs_list_insert(&change->rd.nexthops, &rdnh->nexthop_node);
 
         change->relevant = true;
@@ -384,6 +388,49 @@ route_table_parse__(struct ofpbuf *buf, size_t ofs,
         if (attrs[RTA_PRIORITY]) {
             change->rd.rta_priority = nl_attr_get_u32(attrs[RTA_PRIORITY]);
         }
+        if (attrs[RTA_VIA]) {
+            const struct rtvia *rtvia = nl_attr_get(attrs[RTA_VIA]);
+            ovs_be32 addr;
+
+            if (attrs[RTA_GATEWAY]) {
+                VLOG_DBG_RL(&rl, "route message can not contain both "
+                            "RTA_GATEWAY and RTA_VIA");
+                goto error_out;
+            }
+
+            rdnh->family = rtvia->rtvia_family;
+
+            switch (rdnh->family) {
+            case AF_INET:
+                if (nl_attr_get_size(attrs[RTA_VIA])
+                        - sizeof *rtvia < sizeof addr) {
+                    VLOG_DBG_RL(&rl, "got short message while parsing RTA_VIA "
+                                "attribute for family AF_INET");
+                    goto error_out;
+                }
+                memcpy(&addr, rtvia->rtvia_addr, sizeof addr);
+                in6_addr_set_mapped_ipv4(&rdnh->addr, addr);
+                break;
+            case AF_INET6:
+                if (nl_attr_get_size(attrs[RTA_VIA])
+                        - sizeof *rtvia < sizeof rdnh->addr) {
+                    VLOG_DBG_RL(&rl, "got short message while parsing RTA_VIA "
+                                "attribute for family AF_INET6");
+                    goto error_out;
+                }
+                memcpy(&rdnh->addr, rtvia->rtvia_addr, sizeof rdnh->addr);
+                break;
+            default:
+                VLOG_DBG_RL(&rl, "unsupported address family, %d, "
+                            "in via attribute", rdnh->family);
+                goto error_out;
+            }
+        }
+        if (!attrs[RTA_OIF] && !attrs[RTA_GATEWAY] && !attrs[RTA_VIA]) {
+            VLOG_DBG_RL(&rl, "route message needs an RTA_OIF, RTA_GATEWAY or "
+                        "RTA_VIA attribute");
+            goto error_out;
+        }
     } else {
         VLOG_DBG_RL(&rl, "received unparseable rtnetlink route message");
         goto error_out;

diff --git a/tests/system-route.at b/tests/system-route.at
@@ -65,6 +65,26 @@ Cached: fc00:db8:beef::13/128 dev br0 GW fc00:db8:cafe::1 SRC fc00:db8:cafe::2])
 OVS_TRAFFIC_VSWITCHD_STOP
 AT_CLEANUP
 
+AT_SETUP([ovs-route - add system route - ipv4 via ipv6 nexthop])
+AT_KEYWORDS([route])
+OVS_TRAFFIC_VSWITCHD_START()
+AT_CHECK([ovs-vsctl set bridge br0 other-config:hwaddr=00:53:00:00:00:42])
+AT_CHECK([ip link set br0 up])
+
+AT_CHECK([ip addr add 192.168.9.2/24 dev br0], [0], [stdout])
+
+AT_CHECK([ip route add 192.168.10.12/32 \
+          via inet6 fe80::253:ff:fe00:51 dev br0], [0], [stdout])
+
+AT_CHECK([ovs-appctl revalidator/wait])
+
+OVS_WAIT_UNTIL_EQUAL([ovs-appctl ovs/route/show | \
+                      grep -E '192.168.10.12/32' | sort], [dnl
+Cached: 192.168.10.12/32 dev br0 GW fe80::253:ff:fe00:51 SRC fe80::253:ff:fe00:42])
+
+OVS_TRAFFIC_VSWITCHD_STOP
+AT_CLEANUP
+
 dnl Checks that OVS doesn't use routes from non-standard tables.
 AT_SETUP([ovs-route - route tables])
 AT_KEYWORDS([route])