ofproto-dpif: Allow IPv6 ND Extensions only if supported

The IPv6 ND Extensions is only implemented in userspace datapath,
but nothing prevents that to be used with other datapaths.

This patch probes the datapath and only allows if the support
is available.

Fixes: 9b2b84973 ("Support for match & set ICMPv6 reserved and options type fields")
Acked-by: Eelco Chaudron <echaudro@redhat.com>
Acked-by: Aaron Conole <aconole@redhat.com>
Signed-off-by: Flavio Leitner <fbl@sysclose.org>
Signed-off-by: Ben Pfaff <blp@ovn.org>

1 files changed, 58 insertions, 1 deletions

diff --git a/ofproto/ofproto-dpif.c b/ofproto/ofproto-dpif.c
index fa73d06a8..5360e7209 100644
--- a/ofproto/ofproto-dpif.c
+++ b/ofproto/ofproto-dpif.c
@@ -1470,6 +1470,55 @@ check_max_dp_hash_alg(struct dpif_backer *backer)
     return max_alg;
 }
 
+/* Tests whether 'backer''s datapath supports IPv6 ND extensions.
+ * Only userspace datapath support OVS_KEY_ATTR_ND_EXTENSIONS in keys.
+ *
+ * Returns false if 'backer' definitely does not support matching and
+ * setting reserved and options type, true if it seems to support. */
+static bool
+check_nd_extensions(struct dpif_backer *backer)
+{
+    struct eth_header *eth;
+    struct ofpbuf actions;
+    struct dpif_execute execute;
+    struct dp_packet packet;
+    struct flow flow;
+    int error;
+    struct ovs_key_nd_extensions key, mask;
+
+    ofpbuf_init(&actions, 64);
+    memset(&key, 0x53, sizeof key);
+    memset(&mask, 0x7f, sizeof mask);
+    commit_masked_set_action(&actions, OVS_KEY_ATTR_ND_EXTENSIONS, &key, &mask,
+                             sizeof key);
+
+    /* Compose a dummy ethernet packet. */
+    dp_packet_init(&packet, ETH_HEADER_LEN);
+    eth = dp_packet_put_zeros(&packet, ETH_HEADER_LEN);
+    eth->eth_type = htons(0x1234);
+
+    flow_extract(&packet, &flow);
+
+    /* Execute the actions.  On datapaths without support fails with EINVAL. */
+    execute.actions = actions.data;
+    execute.actions_len = actions.size;
+    execute.packet = &packet;
+    execute.flow = &flow;
+    execute.needs_help = false;
+    execute.probe = true;
+    execute.mtu = 0;
+
+    error = dpif_execute(backer->dpif, &execute);
+
+    dp_packet_uninit(&packet);
+    ofpbuf_uninit(&actions);
+
+    VLOG_INFO("%s: Datapath %s IPv6 ND Extensions", dpif_name(backer->dpif),
+              error ? "does not support" : "supports");
+
+    return !error;
+}
+
 #define CHECK_FEATURE__(NAME, SUPPORT, FIELD, VALUE, ETHTYPE)               \
 static bool                                                                 \
 check_##NAME(struct dpif_backer *backer)                                    \
@@ -1541,10 +1590,10 @@ check_support(struct dpif_backer *backer)
     backer->rt_support.odp.ct_zone = check_ct_zone(backer);
     backer->rt_support.odp.ct_mark = check_ct_mark(backer);
     backer->rt_support.odp.ct_label = check_ct_label(backer);
-
     backer->rt_support.odp.ct_state_nat = check_ct_state_nat(backer);
     backer->rt_support.odp.ct_orig_tuple = check_ct_orig_tuple(backer);
     backer->rt_support.odp.ct_orig_tuple6 = check_ct_orig_tuple6(backer);
+    backer->rt_support.odp.nd_ext = check_nd_extensions(backer);
 }
 
 static int
@@ -4551,6 +4600,14 @@ check_actions(const struct ofproto_dpif *ofproto,
                                        "ct original direction tuple");
                 return OFPERR_NXBAC_CT_DATAPATH_SUPPORT;
             }
+        } else if (!support->nd_ext && ofpact->type == OFPACT_SET_FIELD) {
+            const struct mf_field *dst = ofpact_get_mf_dst(ofpact);
+
+            if (dst->id == MFF_ND_RESERVED || dst->id == MFF_ND_OPTIONS_TYPE) {
+                report_unsupported_act("set field",
+                                       "setting IPv6 ND Extensions fields");
+                return OFPERR_OFPBAC_BAD_SET_ARGUMENT;
+            }
         }
     }