[PATCH 4/6] mpls: VPLS support

[David Lamparter <equinox@diac24.net>]

[work-in-progress, works but needs changes]
[v2: refactored lots of things, e.g. dst_metadata, no more genetlink]

Signed-off-by: David Lamparter <equinox@diac24.net>
---
 include/net/dst_metadata.h |  21 ++
 include/net/vpls.h         |   8 +
 net/mpls/Kconfig           |  11 ++
 net/mpls/Makefile          |   1 +
 net/mpls/vpls.c            | 469 +++++++++++++++++++++++++++++++++++++++++++++
 5 files changed, 510 insertions(+)
 create mode 100644 include/net/vpls.h
 create mode 100644 net/mpls/vpls.c

diff --git a/include/net/dst_metadata.h b/include/net/dst_metadata.h
index 8858dc441458..aeee4ce3b654 100644
--- a/include/net/dst_metadata.h
+++ b/include/net/dst_metadata.h
@@ -3,11 +3,13 @@
 
 #include <linux/skbuff.h>
 #include <net/ip_tunnels.h>
+#include <net/vpls.h>
 #include <net/dst.h>
 
 enum metadata_type {
 	METADATA_IP_TUNNEL,
 	METADATA_HW_PORT_MUX,
+	METADATA_VPLS,
 };
 
 struct hw_port_info {
@@ -21,6 +23,7 @@ struct metadata_dst {
 	union {
 		struct ip_tunnel_info	tun_info;
 		struct hw_port_info	port_info;
+		struct vpls_info	vpls_info;
 	} u;
 };
 
@@ -49,6 +52,15 @@ static inline struct ip_tunnel_info *skb_tunnel_info(struct sk_buff *skb)
 	return NULL;
 }
 
+static inline struct vpls_info *skb_vpls_info(struct sk_buff *skb)
+{
+	struct metadata_dst *md_dst = skb_metadata_dst(skb);
+	if (md_dst && md_dst->type == METADATA_VPLS)
+		return &md_dst->u.vpls_info;
+	return NULL;
+}
+
+
 static inline bool skb_valid_dst(const struct sk_buff *skb)
 {
 	struct dst_entry *dst = skb_dst(skb);
@@ -73,6 +85,9 @@ static inline int dst_metadata_cmp(const struct dst_entry *dst_a,
 	case METADATA_HW_PORT_MUX:
 		return memcmp(&a->u.port_info, &b->u.port_info,
 			      sizeof(a->u.port_info));
+	case METADATA_VPLS:
+		return memcmp(&a->u.vpls_info, &b->u.vpls_info,
+			      sizeof(a->u.vpls_info));
 	case METADATA_IP_TUNNEL:
 		return memcmp(&a->u.tun_info, &b->u.tun_info,
 			      sizeof(a->u.tun_info) +
@@ -218,4 +233,10 @@ static inline struct metadata_dst *ipv6_tun_rx_dst(struct sk_buff *skb,
 				  0, ip6_flowlabel(ip6h), flags, tunnel_id,
 				  md_size);
 }
+
+static inline struct metadata_dst *vpls_rx_dst(void)
+{
+	return metadata_dst_alloc(0, METADATA_VPLS, GFP_ATOMIC);
+}
+
 #endif /* __NET_DST_METADATA_H */
diff --git a/include/net/vpls.h b/include/net/vpls.h
new file mode 100644
index 000000000000..b261e2d97734
--- /dev/null
+++ b/include/net/vpls.h
@@ -0,0 +1,8 @@
+#ifndef __NET_VPLS_H
+#define __NET_VPLS_H 1
+
+struct vpls_info {
+	u32		pw_label;
+};
+
+#endif /* __NET_VPLS_H */
diff --git a/net/mpls/Kconfig b/net/mpls/Kconfig
index 5c467ef97311..c15ba73efb34 100644
--- a/net/mpls/Kconfig
+++ b/net/mpls/Kconfig
@@ -27,6 +27,17 @@ config MPLS_ROUTING
 	---help---
 	 Add support for forwarding of mpls packets.
 
+config MPLS_VPLS
+	bool "VPLS support"
+	default y
+	depends on MPLS_ROUTING && BRIDGE_NETFILTER=n
+	---help---
+	 Add support for de-&encapsulating VPLS.  Not compatible with
+	 bridge netfilter due to the latter stomping over VPLS' dst metadata.
+
+comment "disable 'Bridged IP/ARP packets filtering' for VPLS support"
+	depends on BRIDGE_NETFILTER
+
 config MPLS_IPTUNNEL
 	tristate "MPLS: IP over MPLS tunnel support"
 	depends on LWTUNNEL && MPLS_ROUTING
diff --git a/net/mpls/Makefile b/net/mpls/Makefile
index 9ca923625016..3c028600a980 100644
--- a/net/mpls/Makefile
+++ b/net/mpls/Makefile
@@ -6,3 +6,4 @@ obj-$(CONFIG_MPLS_ROUTING) += mpls_router.o
 obj-$(CONFIG_MPLS_IPTUNNEL) += mpls_iptunnel.o
 
 mpls_router-y := af_mpls.o
+mpls_router-$(CONFIG_MPLS_VPLS) += vpls.o
diff --git a/net/mpls/vpls.c b/net/mpls/vpls.c
new file mode 100644
index 000000000000..28ac810da6e9
--- /dev/null
+++ b/net/mpls/vpls.c
@@ -0,0 +1,469 @@
+/*
+ *  net/mpls/vpls.c
+ *
+ *  Copyright (C) 2016 David Lamparter
+ *
+ */
+
+#include <linux/netdevice.h>
+#include <linux/slab.h>
+#include <linux/ethtool.h>
+#include <linux/etherdevice.h>
+#include <linux/u64_stats_sync.h>
+#include <linux/mpls.h>
+
+#include <net/rtnetlink.h>
+#include <net/dst.h>
+#include <net/xfrm.h>
+#include <net/mpls.h>
+#include <linux/module.h>
+#include <net/dst_metadata.h>
+#include <net/ip_tunnels.h>
+
+#include "internal.h"
+
+#define DRV_NAME	"vpls"
+
+#define MIN_MTU 68		/* Min L3 MTU */
+#define MAX_MTU 65535		/* Max L3 MTU (arbitrary) */
+
+struct vpls_wirelist {
+	struct rcu_head rcu;
+	size_t count;
+	unsigned wires[0];
+};
+
+struct vpls_priv {
+	struct net *encap_net;
+	struct vpls_wirelist __rcu *wires;
+};
+
+static int vpls_xmit_wire(struct sk_buff *skb, struct net_device *dev,
+			  struct vpls_priv *vpls, u32 wire)
+{
+	struct mpls_route *rt;
+	struct mpls_entry_decoded dec;
+
+	dec.bos = 1;
+	dec.ttl = 255;
+
+	rt = mpls_route_input_rcu(vpls->encap_net, wire);
+	if (!rt)
+		return -ENOENT;
+	if (rt->rt_vpls_dev != dev)
+		return -EINVAL;
+
+	return mpls_rt_xmit(skb, rt, dec);
+}
+
+static netdev_tx_t vpls_xmit(struct sk_buff *skb, struct net_device *dev)
+{
+	int err = -EINVAL, ok_count = 0;
+	struct vpls_priv *priv = netdev_priv(dev);
+	struct vpls_info *vi;
+	struct pcpu_sw_netstats *stats;
+	size_t len = skb->len;
+
+	rcu_read_lock();
+	vi = skb_vpls_info(skb);
+
+	skb_orphan(skb);
+	skb_forward_csum(skb);
+
+	if (vi) {
+		err = vpls_xmit_wire(skb, dev, priv, vi->pw_label);
+		if (err)
+			goto out_err;
+	} else {
+		struct sk_buff *cloned;
+		struct vpls_wirelist *wl;
+		size_t i;
+
+		wl = rcu_dereference(priv->wires);
+		if (wl->count == 0) {
+			dev->stats.tx_carrier_errors++;
+			goto out_err;
+		}
+
+		for (i = 0; i < wl->count; i++) {
+			cloned = skb_clone(skb, GFP_KERNEL);
+			if (vpls_xmit_wire(cloned, dev, priv, wl->wires[i]))
+				consume_skb(cloned);
+			else
+				ok_count++;
+		}
+		if (!ok_count)
+			goto out_err;
+
+		consume_skb(skb);
+	}
+
+	stats = this_cpu_ptr(dev->tstats);
+	u64_stats_update_begin(&stats->syncp);
+	stats->tx_packets++;
+	stats->tx_bytes += len;
+	u64_stats_update_end(&stats->syncp);
+
+	rcu_read_unlock();
+	return 0;
+
+out_err:
+	dev->stats.tx_errors++;
+
+	consume_skb(skb);
+	rcu_read_unlock();
+	return err;
+}
+
+int vpls_rcv(struct sk_buff *skb, struct net_device *in_dev,
+	     struct packet_type *pt, struct mpls_route *rt,
+	     struct mpls_shim_hdr *hdr, struct net_device *orig_dev)
+{
+	struct net_device *dev = rt->rt_vpls_dev;
+	struct mpls_entry_decoded dec;
+	struct metadata_dst *md_dst;
+	struct pcpu_sw_netstats *stats;
+
+	if (!dev)
+		goto drop_nodev;
+
+	dec = mpls_entry_decode(hdr);
+	if (!dec.bos) {
+		dev->stats.rx_frame_errors++;
+		goto drop;
+	}
+
+	skb_pull(skb, sizeof(*hdr));
+
+	if (unlikely(!pskb_may_pull(skb, ETH_HLEN))) {
+		dev->stats.rx_length_errors++;
+		goto drop;
+	}
+
+	md_dst = vpls_rx_dst();
+	if (unlikely(!md_dst)) {
+		netdev_err(dev, "failed to allocate dst metadata\n");
+		goto drop;
+	}
+	md_dst->u.vpls_info.pw_label = dec.label;
+
+	skb->dev = dev;
+
+	skb_reset_mac_header(skb);
+	skb->protocol = eth_type_trans(skb, dev);
+	skb->ip_summed = CHECKSUM_NONE;
+	skb->pkt_type = PACKET_HOST;
+
+	skb_clear_hash(skb);
+	skb->vlan_tci = 0;
+	skb_set_queue_mapping(skb, 0);
+	skb_scrub_packet(skb, !net_eq(dev_net(in_dev), dev_net(dev)));
+
+	skb_reset_network_header(skb);
+	skb_probe_transport_header(skb, 0);
+
+	skb_dst_drop(skb);
+	skb_dst_set(skb, &md_dst->dst);
+
+	stats = this_cpu_ptr(dev->tstats);
+	u64_stats_update_begin(&stats->syncp);
+	stats->rx_packets++;
+	stats->rx_bytes += skb->len;
+	u64_stats_update_end(&stats->syncp);
+
+	netif_rx(skb);
+	return 0;
+
+drop:
+	dev->stats.rx_errors++;
+drop_nodev:
+	kfree_skb(skb);
+	return NET_RX_DROP;
+}
+
+void vpls_label_update(unsigned label, struct mpls_route *rt_old,
+		       struct mpls_route *rt_new)
+{
+	struct vpls_priv *priv;
+	struct vpls_wirelist *wl, *wl_new;
+	size_t i;
+
+	ASSERT_RTNL();
+
+	if (rt_old && rt_new && rt_old->rt_vpls_dev == rt_new->rt_vpls_dev)
+		return;
+
+	if (rt_old && rt_old->rt_vpls_dev) {
+		priv = netdev_priv(rt_old->rt_vpls_dev);
+		wl = rcu_dereference(priv->wires);
+
+		for (i = 0; i < wl->count; i++)
+			if (wl->wires[i] == label)
+				break;
+
+		if (i == wl->count) {
+			netdev_err(rt_old->rt_vpls_dev,
+				   "can't find pseudowire to remove!\n");
+			goto update_new;
+		}
+
+		wl_new = kmalloc(sizeof(*wl) +
+				 (wl->count - 1) * sizeof(wl->wires[0]),
+				 GFP_ATOMIC);
+		if (!wl_new) {
+			netdev_err(rt_old->rt_vpls_dev,
+				   "out of memory for pseudowire delete!\n");
+			goto update_new;
+		}
+
+		wl_new->count = wl->count - 1;
+		memcpy(wl_new->wires, wl->wires, i * sizeof(wl->wires[0]));
+		memcpy(wl_new->wires + i, wl->wires + i + 1,
+			(wl->count - i - 1) * sizeof(wl->wires[0]));
+
+		rcu_assign_pointer(priv->wires, wl_new);
+		kfree_rcu(wl, rcu);
+
+		if (wl_new->count == 0)
+			netif_carrier_off(rt_old->rt_vpls_dev);
+	}
+
+update_new:
+	if (rt_new && rt_new->rt_vpls_dev) {
+		priv = netdev_priv(rt_new->rt_vpls_dev);
+		wl = rcu_dereference(priv->wires);
+
+		wl_new = kmalloc(sizeof(*wl) +
+				 (wl->count + 1) * sizeof(wl->wires[0]),
+				 GFP_ATOMIC);
+		if (!wl_new) {
+			netdev_err(rt_new->rt_vpls_dev,
+				   "out of memory for pseudowire add!\n");
+			return;
+		}
+		wl_new->count = wl->count + 1;
+		memcpy(wl_new->wires, wl->wires,
+			wl->count * sizeof(wl->wires[0]));
+		wl_new->wires[wl->count] = label;
+
+		rcu_assign_pointer(priv->wires, wl_new);
+		kfree_rcu(wl, rcu);
+
+		if (wl_new->count == 1)
+			netif_carrier_on(rt_new->rt_vpls_dev);
+	}
+}
+
+/* fake multicast ability */
+static void vpls_set_multicast_list(struct net_device *dev)
+{
+}
+
+static int vpls_open(struct net_device *dev)
+{
+	struct vpls_priv *priv = netdev_priv(dev);
+	struct vpls_wirelist *wl;
+
+	wl = rcu_dereference(priv->wires);
+	if (wl->count > 0)
+		netif_carrier_on(dev);
+
+	return 0;
+}
+
+static int vpls_close(struct net_device *dev)
+{
+	netif_carrier_off(dev);
+	return 0;
+}
+
+static int is_valid_vpls_mtu(int new_mtu)
+{
+	return new_mtu >= MIN_MTU && new_mtu <= MAX_MTU;
+}
+
+static int vpls_change_mtu(struct net_device *dev, int new_mtu)
+{
+	if (!is_valid_vpls_mtu(new_mtu))
+		return -EINVAL;
+	dev->mtu = new_mtu;
+	return 0;
+}
+
+static int vpls_dev_init(struct net_device *dev)
+{
+	struct vpls_priv *priv = netdev_priv(dev);
+	priv->wires = kzalloc(sizeof(struct vpls_wirelist), GFP_KERNEL);
+	if (!priv->wires)
+		return -ENOMEM;
+
+	dev->tstats = netdev_alloc_pcpu_stats(struct pcpu_sw_netstats);
+	if (!dev->tstats) {
+		kfree(priv->wires);
+		return -ENOMEM;
+	}
+
+	return 0;
+}
+
+static void vpls_dev_free(struct net_device *dev)
+{
+	struct vpls_priv *priv = netdev_priv(dev);
+
+	free_percpu(dev->tstats);
+
+	if (priv->wires)
+		kfree(priv->wires);
+
+	if (priv->encap_net)
+		put_net(priv->encap_net);
+
+	free_netdev(dev);
+}
+
+static const struct net_device_ops vpls_netdev_ops = {
+	.ndo_init		= vpls_dev_init,
+	.ndo_open		= vpls_open,
+	.ndo_stop		= vpls_close,
+	.ndo_start_xmit		= vpls_xmit,
+	.ndo_change_mtu		= vpls_change_mtu,
+	.ndo_get_stats64	= ip_tunnel_get_stats64,
+	.ndo_set_rx_mode	= vpls_set_multicast_list,
+	.ndo_set_mac_address	= eth_mac_addr,
+	.ndo_features_check	= passthru_features_check,
+};
+
+int is_vpls_dev(struct net_device *dev)
+{
+	return dev->netdev_ops == &vpls_netdev_ops;
+}
+
+#define VPLS_FEATURES (NETIF_F_SG | NETIF_F_FRAGLIST | \
+		       NETIF_F_HW_CSUM | NETIF_F_RXCSUM | NETIF_F_HIGHDMA)
+
+static void vpls_setup(struct net_device *dev)
+{
+	ether_setup(dev);
+
+	dev->priv_flags &= ~IFF_TX_SKB_SHARING;
+	dev->priv_flags |= IFF_LIVE_ADDR_CHANGE;
+	dev->priv_flags |= IFF_NO_QUEUE;
+
+	dev->netdev_ops = &vpls_netdev_ops;
+	dev->features |= NETIF_F_LLTX;
+	dev->features |= VPLS_FEATURES;
+	dev->vlan_features = dev->features;
+	dev->priv_destructor = vpls_dev_free;
+
+	dev->hw_features = VPLS_FEATURES;
+	dev->hw_enc_features = VPLS_FEATURES;
+
+	netif_keep_dst(dev);
+}
+
+/*
+ * netlink interface
+ */
+
+static int vpls_validate(struct nlattr *tb[], struct nlattr *data[],
+			 struct netlink_ext_ack *extack)
+{
+	if (tb[IFLA_ADDRESS]) {
+		if (nla_len(tb[IFLA_ADDRESS]) != ETH_ALEN) {
+			NL_SET_ERR_MSG_ATTR(extack, tb[IFLA_ADDRESS],
+				    "Invalid Ethernet address length");
+			return -EINVAL;
+		}
+		if (!is_valid_ether_addr(nla_data(tb[IFLA_ADDRESS]))) {
+			NL_SET_ERR_MSG_ATTR(extack, tb[IFLA_ADDRESS],
+				    "Invalid Ethernet address");
+			return -EADDRNOTAVAIL;
+		}
+	}
+	if (tb[IFLA_MTU]) {
+		if (!is_valid_vpls_mtu(nla_get_u32(tb[IFLA_MTU]))) {
+			NL_SET_ERR_MSG_ATTR(extack, tb[IFLA_MTU],
+				    "Invalid MTU");
+			return -EINVAL;
+		}
+	}
+	return 0;
+}
+
+static struct rtnl_link_ops vpls_link_ops;
+
+static int vpls_newlink(struct net *src_net, struct net_device *dev,
+			struct nlattr *tb[], struct nlattr *data[],
+			struct netlink_ext_ack *extack)
+{
+	int err;
+	struct vpls_priv *priv = netdev_priv(dev);
+
+	if (tb[IFLA_ADDRESS] == NULL)
+		eth_hw_addr_random(dev);
+
+	if (tb[IFLA_IFNAME])
+		nla_strlcpy(dev->name, tb[IFLA_IFNAME], IFNAMSIZ);
+	else
+		snprintf(dev->name, IFNAMSIZ, DRV_NAME "%%d");
+
+	err = register_netdevice(dev);
+	if (err < 0)
+		goto err;
+	priv->encap_net = get_net(src_net);
+
+	netif_carrier_off(dev);
+	return 0;
+
+err:
+	return err;
+}
+
+static void vpls_dellink(struct net_device *dev, struct list_head *head)
+{
+	unregister_netdevice_queue(dev, head);
+}
+
+
+static struct rtnl_link_ops vpls_link_ops = {
+	.kind		= DRV_NAME,
+	.priv_size	= sizeof(struct vpls_priv),
+	.setup		= vpls_setup,
+	.validate	= vpls_validate,
+	.newlink	= vpls_newlink,
+	.dellink	= vpls_dellink,
+};
+
+/*
+ * init/fini
+ */
+
+__init int vpls_init(void)
+{
+	int ret;
+
+	ret = rtnl_link_register(&vpls_link_ops);
+	if (ret)
+		goto out;
+
+	return 0;
+
+out:
+	return ret;
+}
+
+__exit void vpls_exit(void)
+{
+	rtnl_link_unregister(&vpls_link_ops);
+}
+
+#if 0
+/* not currently available as a separate module... */
+
+module_init(vpls_init);
+module_exit(vpls_exit);
+
+MODULE_DESCRIPTION("Virtual Private LAN Service");
+MODULE_LICENSE("GPL v2");
+MODULE_ALIAS_RTNL_LINK(DRV_NAME);
+#endif
-- 
2.13.0