ip6_gre: add ip6 erspan collect_md mode

Similar to ip6 gretap and ip4 gretap, the patch allows
erspan tunnel to operate in collect metadata mode.
bpf_skb_[gs]et_tunnel_key() helpers can make use of
it right away.

Signed-off-by: William Tu <u9012063@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/ipv6/ip6_gre.c b/net/ipv6/ip6_gre.c
index 1510ce9a4e4eb3730ba323d00296aa0cc904e864..4562579797d1a83243dd9d70effa93d4cf1fe4a2 100644 (file)
--- a/net/ipv6/ip6_gre.c
+++ b/net/ipv6/ip6_gre.c
@@ -524,8 +524,37 @@ static int ip6erspan_rcv(struct sk_buff *skb, int gre_hdr_len,
                                           false, false) < 0)
                        return PACKET_REJECT;
 
-               tunnel->parms.index = ntohl(index);
-               ip6_tnl_rcv(tunnel, skb, tpi, NULL, log_ecn_error);
+               if (tunnel->parms.collect_md) {
+                       struct metadata_dst *tun_dst;
+                       struct ip_tunnel_info *info;
+                       struct erspan_metadata *md;
+                       __be64 tun_id;
+                       __be16 flags;
+
+                       tpi->flags |= TUNNEL_KEY;
+                       flags = tpi->flags;
+                       tun_id = key32_to_tunnel_id(tpi->key);
+
+                       tun_dst = ipv6_tun_rx_dst(skb, flags, tun_id,
+                                                 sizeof(*md));
+                       if (!tun_dst)
+                               return PACKET_REJECT;
+
+                       info = &tun_dst->u.tun_info;
+                       md = ip_tunnel_info_opts(info);
+                       if (!md)
+                               return PACKET_REJECT;
+
+                       md->index = index;
+                       info->key.tun_flags |= TUNNEL_ERSPAN_OPT;
+                       info->options_len = sizeof(*md);
+
+                       ip6_tnl_rcv(tunnel, skb, tpi, tun_dst, log_ecn_error);
+
+               } else {
+                       tunnel->parms.index = ntohl(index);
+                       ip6_tnl_rcv(tunnel, skb, tpi, NULL, log_ecn_error);
+               }
 
                return PACKET_RCVD;
        }
@@ -857,42 +886,73 @@ static netdev_tx_t ip6erspan_tunnel_xmit(struct sk_buff *skb,
        if (gre_handle_offloads(skb, false))
                goto tx_err;
 
-       switch (skb->protocol) {
-       case htons(ETH_P_IP):
-               memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
-               prepare_ip6gre_xmit_ipv4(skb, dev, &fl6,
-                                        &dsfield, &encap_limit);
-               break;
-       case htons(ETH_P_IPV6):
-               if (ipv6_addr_equal(&t->parms.raddr, &ipv6h->saddr))
-                       goto tx_err;
-               if (prepare_ip6gre_xmit_ipv6(skb, dev, &fl6,
-                                            &dsfield, &encap_limit))
-                       goto tx_err;
-               break;
-       default:
-               memcpy(&fl6, &t->fl.u.ip6, sizeof(fl6));
-               break;
-       }
-
        if (skb->len > dev->mtu + dev->hard_header_len) {
                pskb_trim(skb, dev->mtu + dev->hard_header_len);
                truncate = true;
        }
 
-       erspan_build_header(skb, t->parms.o_key, t->parms.index,
-                           truncate, false);
        t->parms.o_flags &= ~TUNNEL_KEY;
-
        IPCB(skb)->flags = 0;
-       fl6.daddr = t->parms.raddr;
+
+       /* For collect_md mode, derive fl6 from the tunnel key,
+        * for native mode, call prepare_ip6gre_xmit_{ipv4,ipv6}.
+        */
+       if (t->parms.collect_md) {
+               struct ip_tunnel_info *tun_info;
+               const struct ip_tunnel_key *key;
+               struct erspan_metadata *md;
+
+               tun_info = skb_tunnel_info(skb);
+               if (unlikely(!tun_info ||
+                            !(tun_info->mode & IP_TUNNEL_INFO_TX) ||
+                            ip_tunnel_info_af(tun_info) != AF_INET6))
+                       return -EINVAL;
+
+               key = &tun_info->key;
+               memset(&fl6, 0, sizeof(fl6));
+               fl6.flowi6_proto = IPPROTO_GRE;
+               fl6.daddr = key->u.ipv6.dst;
+               fl6.flowlabel = key->label;
+               fl6.flowi6_uid = sock_net_uid(dev_net(dev), NULL);
+
+               dsfield = key->tos;
+               md = ip_tunnel_info_opts(tun_info);
+               if (!md)
+                       goto tx_err;
+
+               erspan_build_header(skb, tunnel_id_to_key32(key->tun_id),
+                                   ntohl(md->index), truncate, false);
+
+       } else {
+               switch (skb->protocol) {
+               case htons(ETH_P_IP):
+                       memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
+                       prepare_ip6gre_xmit_ipv4(skb, dev, &fl6,
+                                                &dsfield, &encap_limit);
+                       break;
+               case htons(ETH_P_IPV6):
+                       if (ipv6_addr_equal(&t->parms.raddr, &ipv6h->saddr))
+                               goto tx_err;
+                       if (prepare_ip6gre_xmit_ipv6(skb, dev, &fl6,
+                                                    &dsfield, &encap_limit))
+                               goto tx_err;
+                       break;
+               default:
+                       memcpy(&fl6, &t->fl.u.ip6, sizeof(fl6));
+                       break;
+               }
+
+               erspan_build_header(skb, t->parms.o_key, t->parms.index,
+                                   truncate, false);
+               fl6.daddr = t->parms.raddr;
+       }
 
        /* Push GRE header. */
        gre_build_header(skb, 8, TUNNEL_SEQ,
                         htons(ETH_P_ERSPAN), 0, htonl(t->o_seqno++));
 
        /* TooBig packet may have updated dst->dev's mtu */
-       if (dst && dst_mtu(dst) > dst->dev->mtu)
+       if (!t->parms.collect_md && dst && dst_mtu(dst) > dst->dev->mtu)
                dst->ops->update_pmtu(dst, NULL, skb, dst->dev->mtu);
 
        err = ip6_tnl_xmit(skb, dev, dsfield, &fl6, encap_limit, &mtu,