vxlan: implement GPE

Implement VXLAN-GPE. Only COLLECT_METADATA is supported for now (it is
possible to support static configuration, too, if there is demand for it).

The GPE header parsing has to be moved before iptunnel_pull_header, as we
need to know the protocol.

v2: Removed what was called "L2 mode" in v1 of the patchset. Only "L3 mode"
    (now called "raw mode") is added by this patch. This mode does not allow
    Ethernet header to be encapsulated in VXLAN-GPE when using ip route to
    specify the encapsulation, IP header is encapsulated instead. The patch
    does support Ethernet to be encapsulated, though, using ETH_P_TEB in
    skb->protocol. This will be utilized by other COLLECT_METADATA users
    (openvswitch in particular).

    If there is ever demand for Ethernet encapsulation with VXLAN-GPE using
    ip route, it's easy to add a new flag switching the interface to
    "Ethernet mode" (called "L2 mode" in v1 of this patchset). For now,
    leave this out, it seems we don't need it.

    Disallowed more flag combinations, especially RCO with GPE.
    Added comment explaining that GBP and GPE cannot be set together.

Signed-off-by: Jiri Benc <jbenc@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 153 insertions, 17 deletions

diff --git a/drivers/net/vxlan.c b/drivers/net/vxlan.c
index d62eebaa9720..51cccddfe403 100644
--- a/drivers/net/vxlan.c
+++ b/drivers/net/vxlan.c
@@ -1192,6 +1192,45 @@ out:
 	unparsed->vx_flags &= ~VXLAN_GBP_USED_BITS;
 }
 
+static bool vxlan_parse_gpe_hdr(struct vxlanhdr *unparsed,
+				__be32 *protocol,
+				struct sk_buff *skb, u32 vxflags)
+{
+	struct vxlanhdr_gpe *gpe = (struct vxlanhdr_gpe *)unparsed;
+
+	/* Need to have Next Protocol set for interfaces in GPE mode. */
+	if (!gpe->np_applied)
+		return false;
+	/* "The initial version is 0. If a receiver does not support the
+	 * version indicated it MUST drop the packet.
+	 */
+	if (gpe->version != 0)
+		return false;
+	/* "When the O bit is set to 1, the packet is an OAM packet and OAM
+	 * processing MUST occur." However, we don't implement OAM
+	 * processing, thus drop the packet.
+	 */
+	if (gpe->oam_flag)
+		return false;
+
+	switch (gpe->next_protocol) {
+	case VXLAN_GPE_NP_IPV4:
+		*protocol = htons(ETH_P_IP);
+		break;
+	case VXLAN_GPE_NP_IPV6:
+		*protocol = htons(ETH_P_IPV6);
+		break;
+	case VXLAN_GPE_NP_ETHERNET:
+		*protocol = htons(ETH_P_TEB);
+		break;
+	default:
+		return false;
+	}
+
+	unparsed->vx_flags &= ~VXLAN_GPE_USED_BITS;
+	return true;
+}
+
 static bool vxlan_set_mac(struct vxlan_dev *vxlan,
 			  struct vxlan_sock *vs,
 			  struct sk_buff *skb)
@@ -1257,9 +1296,11 @@ static int vxlan_rcv(struct sock *sk, struct sk_buff *skb)
 	struct vxlanhdr unparsed;
 	struct vxlan_metadata _md;
 	struct vxlan_metadata *md = &_md;
+	__be32 protocol = htons(ETH_P_TEB);
+	bool raw_proto = false;
 	void *oiph;
 
-	/* Need Vxlan and inner Ethernet header to be present */
+	/* Need UDP and VXLAN header to be present */
 	if (!pskb_may_pull(skb, VXLAN_HLEN))
 		return 1;
 
@@ -1283,9 +1324,18 @@ static int vxlan_rcv(struct sock *sk, struct sk_buff *skb)
 	if (!vxlan)
 		goto drop;
 
-	if (iptunnel_pull_header(skb, VXLAN_HLEN, htons(ETH_P_TEB),
-				 !net_eq(vxlan->net, dev_net(vxlan->dev))))
-		goto drop;
+	/* For backwards compatibility, only allow reserved fields to be
+	 * used by VXLAN extensions if explicitly requested.
+	 */
+	if (vs->flags & VXLAN_F_GPE) {
+		if (!vxlan_parse_gpe_hdr(&unparsed, &protocol, skb, vs->flags))
+			goto drop;
+		raw_proto = true;
+	}
+
+	if (__iptunnel_pull_header(skb, VXLAN_HLEN, protocol, raw_proto,
+				   !net_eq(vxlan->net, dev_net(vxlan->dev))))
+			goto drop;
 
 	if (vxlan_collect_metadata(vs)) {
 		__be32 vni = vxlan_vni(vxlan_hdr(skb)->vx_vni);
@@ -1304,14 +1354,14 @@ static int vxlan_rcv(struct sock *sk, struct sk_buff *skb)
 		memset(md, 0, sizeof(*md));
 	}
 
-	/* For backwards compatibility, only allow reserved fields to be
-	 * used by VXLAN extensions if explicitly requested.
-	 */
 	if (vs->flags & VXLAN_F_REMCSUM_RX)
 		if (!vxlan_remcsum(&unparsed, skb, vs->flags))
 			goto drop;
 	if (vs->flags & VXLAN_F_GBP)
 		vxlan_parse_gbp_hdr(&unparsed, skb, vs->flags, md);
+	/* Note that GBP and GPE can never be active together. This is
+	 * ensured in vxlan_dev_configure.
+	 */
 
 	if (unparsed.vx_flags || unparsed.vx_vni) {
 		/* If there are any unprocessed flags remaining treat
@@ -1325,8 +1375,13 @@ static int vxlan_rcv(struct sock *sk, struct sk_buff *skb)
 		goto drop;
 	}
 
-	if (!vxlan_set_mac(vxlan, vs, skb))
-		goto drop;
+	if (!raw_proto) {
+		if (!vxlan_set_mac(vxlan, vs, skb))
+			goto drop;
+	} else {
+		skb->dev = vxlan->dev;
+		skb->pkt_type = PACKET_HOST;
+	}
 
 	oiph = skb_network_header(skb);
 	skb_reset_network_header(skb);
@@ -1685,6 +1740,27 @@ static void vxlan_build_gbp_hdr(struct vxlanhdr *vxh, u32 vxflags,
 	gbp->policy_id = htons(md->gbp & VXLAN_GBP_ID_MASK);
 }
 
+static int vxlan_build_gpe_hdr(struct vxlanhdr *vxh, u32 vxflags,
+			       __be16 protocol)
+{
+	struct vxlanhdr_gpe *gpe = (struct vxlanhdr_gpe *)vxh;
+
+	gpe->np_applied = 1;
+
+	switch (protocol) {
+	case htons(ETH_P_IP):
+		gpe->next_protocol = VXLAN_GPE_NP_IPV4;
+		return 0;
+	case htons(ETH_P_IPV6):
+		gpe->next_protocol = VXLAN_GPE_NP_IPV6;
+		return 0;
+	case htons(ETH_P_TEB):
+		gpe->next_protocol = VXLAN_GPE_NP_ETHERNET;
+		return 0;
+	}
+	return -EPFNOSUPPORT;
+}
+
 static int vxlan_build_skb(struct sk_buff *skb, struct dst_entry *dst,
 			   int iphdr_len, __be32 vni,
 			   struct vxlan_metadata *md, u32 vxflags,
@@ -1694,6 +1770,7 @@ static int vxlan_build_skb(struct sk_buff *skb, struct dst_entry *dst,
 	int min_headroom;
 	int err;
 	int type = udp_sum ? SKB_GSO_UDP_TUNNEL_CSUM : SKB_GSO_UDP_TUNNEL;
+	__be16 inner_protocol = htons(ETH_P_TEB);
 
 	if ((vxflags & VXLAN_F_REMCSUM_TX) &&
 	    skb->ip_summed == CHECKSUM_PARTIAL) {
@@ -1712,10 +1789,8 @@ static int vxlan_build_skb(struct sk_buff *skb, struct dst_entry *dst,
 
 	/* Need space for new headers (invalidates iph ptr) */
 	err = skb_cow_head(skb, min_headroom);
-	if (unlikely(err)) {
-		kfree_skb(skb);
-		return err;
-	}
+	if (unlikely(err))
+		goto out_free;
 
 	skb = vlan_hwaccel_push_inside(skb);
 	if (WARN_ON(!skb))
@@ -1744,9 +1819,19 @@ static int vxlan_build_skb(struct sk_buff *skb, struct dst_entry *dst,
 
 	if (vxflags & VXLAN_F_GBP)
 		vxlan_build_gbp_hdr(vxh, vxflags, md);
+	if (vxflags & VXLAN_F_GPE) {
+		err = vxlan_build_gpe_hdr(vxh, vxflags, skb->protocol);
+		if (err < 0)
+			goto out_free;
+		inner_protocol = skb->protocol;
+	}
 
-	skb_set_inner_protocol(skb, htons(ETH_P_TEB));
+	skb_set_inner_protocol(skb, inner_protocol);
 	return 0;
+
+out_free:
+	kfree_skb(skb);
+	return err;
 }
 
 static struct rtable *vxlan_get_route(struct vxlan_dev *vxlan,
@@ -2421,6 +2506,17 @@ static const struct net_device_ops vxlan_netdev_ether_ops = {
 	.ndo_fill_metadata_dst	= vxlan_fill_metadata_dst,
 };
 
+static const struct net_device_ops vxlan_netdev_raw_ops = {
+	.ndo_init		= vxlan_init,
+	.ndo_uninit		= vxlan_uninit,
+	.ndo_open		= vxlan_open,
+	.ndo_stop		= vxlan_stop,
+	.ndo_start_xmit		= vxlan_xmit,
+	.ndo_get_stats64	= ip_tunnel_get_stats64,
+	.ndo_change_mtu		= vxlan_change_mtu,
+	.ndo_fill_metadata_dst	= vxlan_fill_metadata_dst,
+};
+
 /* Info for udev, that this is a virtual tunnel endpoint */
 static struct device_type vxlan_type = {
 	.name = "vxlan",
@@ -2500,6 +2596,17 @@ static void vxlan_ether_setup(struct net_device *dev)
 	dev->netdev_ops = &vxlan_netdev_ether_ops;
 }
 
+static void vxlan_raw_setup(struct net_device *dev)
+{
+	dev->type = ARPHRD_NONE;
+	dev->hard_header_len = 0;
+	dev->addr_len = 0;
+	dev->mtu = ETH_DATA_LEN;
+	dev->tx_queue_len = 1000;
+	dev->flags = IFF_POINTOPOINT | IFF_NOARP | IFF_MULTICAST;
+	dev->netdev_ops = &vxlan_netdev_raw_ops;
+}
+
 static const struct nla_policy vxlan_policy[IFLA_VXLAN_MAX + 1] = {
 	[IFLA_VXLAN_ID]		= { .type = NLA_U32 },
 	[IFLA_VXLAN_GROUP]	= { .len = FIELD_SIZEOF(struct iphdr, daddr) },
@@ -2526,6 +2633,7 @@ static const struct nla_policy vxlan_policy[IFLA_VXLAN_MAX + 1] = {
 	[IFLA_VXLAN_REMCSUM_TX]	= { .type = NLA_U8 },
 	[IFLA_VXLAN_REMCSUM_RX]	= { .type = NLA_U8 },
 	[IFLA_VXLAN_GBP]	= { .type = NLA_FLAG, },
+	[IFLA_VXLAN_GPE]	= { .type = NLA_FLAG, },
 	[IFLA_VXLAN_REMCSUM_NOPARTIAL]	= { .type = NLA_FLAG },
 };
 
@@ -2726,7 +2834,20 @@ static int vxlan_dev_configure(struct net *src_net, struct net_device *dev,
 	__be16 default_port = vxlan->cfg.dst_port;
 	struct net_device *lowerdev = NULL;
 
-	vxlan_ether_setup(dev);
+	if (conf->flags & VXLAN_F_GPE) {
+		if (conf->flags & ~VXLAN_F_ALLOWED_GPE)
+			return -EINVAL;
+		/* For now, allow GPE only together with COLLECT_METADATA.
+		 * This can be relaxed later; in such case, the other side
+		 * of the PtP link will have to be provided.
+		 */
+		if (!(conf->flags & VXLAN_F_COLLECT_METADATA))
+			return -EINVAL;
+
+		vxlan_raw_setup(dev);
+	} else {
+		vxlan_ether_setup(dev);
+	}
 
 	vxlan->net = src_net;
 
@@ -2789,8 +2910,12 @@ static int vxlan_dev_configure(struct net *src_net, struct net_device *dev,
 	dev->needed_headroom = needed_headroom;
 
 	memcpy(&vxlan->cfg, conf, sizeof(*conf));
-	if (!vxlan->cfg.dst_port)
-		vxlan->cfg.dst_port = default_port;
+	if (!vxlan->cfg.dst_port) {
+		if (conf->flags & VXLAN_F_GPE)
+			vxlan->cfg.dst_port = 4790; /* IANA assigned VXLAN-GPE port */
+		else
+			vxlan->cfg.dst_port = default_port;
+	}
 	vxlan->flags |= conf->flags;
 
 	if (!vxlan->cfg.age_interval)
@@ -2961,6 +3086,9 @@ static int vxlan_newlink(struct net *src_net, struct net_device *dev,
 	if (data[IFLA_VXLAN_GBP])
 		conf.flags |= VXLAN_F_GBP;
 
+	if (data[IFLA_VXLAN_GPE])
+		conf.flags |= VXLAN_F_GPE;
+
 	if (data[IFLA_VXLAN_REMCSUM_NOPARTIAL])
 		conf.flags |= VXLAN_F_REMCSUM_NOPARTIAL;
 
@@ -2977,6 +3105,10 @@ static int vxlan_newlink(struct net *src_net, struct net_device *dev,
 	case -EEXIST:
 		pr_info("duplicate VNI %u\n", be32_to_cpu(conf.vni));
 		break;
+
+	case -EINVAL:
+		pr_info("unsupported combination of extensions\n");
+		break;
 	}
 
 	return err;
@@ -3104,6 +3236,10 @@ static int vxlan_fill_info(struct sk_buff *skb, const struct net_device *dev)
 	    nla_put_flag(skb, IFLA_VXLAN_GBP))
 		goto nla_put_failure;
 
+	if (vxlan->flags & VXLAN_F_GPE &&
+	    nla_put_flag(skb, IFLA_VXLAN_GPE))
+		goto nla_put_failure;
+
 	if (vxlan->flags & VXLAN_F_REMCSUM_NOPARTIAL &&
 	    nla_put_flag(skb, IFLA_VXLAN_REMCSUM_NOPARTIAL))
 		goto nla_put_failure;