mpls: ip tunnel support
This implementation uses lwtunnel infrastructure to register
hooks for mpls tunnel encaps.
It picks cues from iptunnel_encaps infrastructure and previous
mpls iptunnel RFC patches from Eric W. Biederman and Robert Shearman
Signed-off-by: Roopa Prabhu <roopa@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/mpls/mpls_iptunnel.c b/net/mpls/mpls_iptunnel.c
new file mode 100644
index 0000000..eea096f
--- /dev/null
+++ b/net/mpls/mpls_iptunnel.c
@@ -0,0 +1,233 @@
+/*
+ * mpls tunnels An implementation mpls tunnels using the light weight tunnel
+ * infrastructure
+ *
+ * Authors: Roopa Prabhu, <roopa@cumulusnetworks.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ *
+ */
+#include <linux/types.h>
+#include <linux/skbuff.h>
+#include <linux/net.h>
+#include <linux/module.h>
+#include <linux/mpls.h>
+#include <linux/vmalloc.h>
+#include <net/ip.h>
+#include <net/dst.h>
+#include <net/lwtunnel.h>
+#include <net/netevent.h>
+#include <net/netns/generic.h>
+#include <net/ip6_fib.h>
+#include <net/route.h>
+#include <net/mpls_iptunnel.h>
+#include <linux/mpls_iptunnel.h>
+#include "internal.h"
+
+static const struct nla_policy mpls_iptunnel_policy[MPLS_IPTUNNEL_MAX + 1] = {
+ [MPLS_IPTUNNEL_DST] = { .type = NLA_U32 },
+};
+
+static unsigned int mpls_encap_size(struct mpls_iptunnel_encap *en)
+{
+ /* The size of the layer 2.5 labels to be added for this route */
+ return en->labels * sizeof(struct mpls_shim_hdr);
+}
+
+int mpls_output(struct sock *sk, struct sk_buff *skb)
+{
+ struct mpls_iptunnel_encap *tun_encap_info;
+ struct mpls_shim_hdr *hdr;
+ struct net_device *out_dev;
+ unsigned int hh_len;
+ unsigned int new_header_size;
+ unsigned int mtu;
+ struct dst_entry *dst = skb_dst(skb);
+ struct rtable *rt = NULL;
+ struct rt6_info *rt6 = NULL;
+ struct lwtunnel_state *lwtstate = NULL;
+ int err = 0;
+ bool bos;
+ int i;
+ unsigned int ttl;
+
+ /* Obtain the ttl */
+ if (skb->protocol == htons(ETH_P_IP)) {
+ ttl = ip_hdr(skb)->ttl;
+ rt = (struct rtable *)dst;
+ lwtstate = rt->rt_lwtstate;
+ } else if (skb->protocol == htons(ETH_P_IPV6)) {
+ ttl = ipv6_hdr(skb)->hop_limit;
+ rt6 = (struct rt6_info *)dst;
+ lwtstate = rt6->rt6i_lwtstate;
+ } else {
+ goto drop;
+ }
+
+ skb_orphan(skb);
+
+ /* Find the output device */
+ out_dev = rcu_dereference(dst->dev);
+ if (!mpls_output_possible(out_dev) ||
+ !lwtstate || skb_warn_if_lro(skb))
+ goto drop;
+
+ skb_forward_csum(skb);
+
+ tun_encap_info = mpls_lwtunnel_encap(lwtstate);
+
+ /* Verify the destination can hold the packet */
+ new_header_size = mpls_encap_size(tun_encap_info);
+ mtu = mpls_dev_mtu(out_dev);
+ if (mpls_pkt_too_big(skb, mtu - new_header_size))
+ goto drop;
+
+ hh_len = LL_RESERVED_SPACE(out_dev);
+ if (!out_dev->header_ops)
+ hh_len = 0;
+
+ /* Ensure there is enough space for the headers in the skb */
+ if (skb_cow(skb, hh_len + new_header_size))
+ goto drop;
+
+ skb_push(skb, new_header_size);
+ skb_reset_network_header(skb);
+
+ skb->dev = out_dev;
+ skb->protocol = htons(ETH_P_MPLS_UC);
+
+ /* Push the new labels */
+ hdr = mpls_hdr(skb);
+ bos = true;
+ for (i = tun_encap_info->labels - 1; i >= 0; i--) {
+ hdr[i] = mpls_entry_encode(tun_encap_info->label[i],
+ ttl, 0, bos);
+ bos = false;
+ }
+
+ if (rt)
+ err = neigh_xmit(NEIGH_ARP_TABLE, out_dev, &rt->rt_gateway,
+ skb);
+ else if (rt6)
+ err = neigh_xmit(NEIGH_ND_TABLE, out_dev, &rt6->rt6i_gateway,
+ skb);
+ if (err)
+ net_dbg_ratelimited("%s: packet transmission failed: %d\n",
+ __func__, err);
+
+ return 0;
+
+drop:
+ kfree_skb(skb);
+ return -EINVAL;
+}
+
+static int mpls_build_state(struct net_device *dev, struct nlattr *nla,
+ struct lwtunnel_state **ts)
+{
+ struct mpls_iptunnel_encap *tun_encap_info;
+ struct nlattr *tb[MPLS_IPTUNNEL_MAX + 1];
+ struct lwtunnel_state *newts;
+ int tun_encap_info_len;
+ int ret;
+
+ ret = nla_parse_nested(tb, MPLS_IPTUNNEL_MAX, nla,
+ mpls_iptunnel_policy);
+ if (ret < 0)
+ return ret;
+
+ if (!tb[MPLS_IPTUNNEL_DST])
+ return -EINVAL;
+
+ tun_encap_info_len = sizeof(*tun_encap_info);
+
+ newts = lwtunnel_state_alloc(tun_encap_info_len);
+ if (!newts)
+ return -ENOMEM;
+
+ newts->len = tun_encap_info_len;
+ tun_encap_info = mpls_lwtunnel_encap(newts);
+ ret = nla_get_labels(tb[MPLS_IPTUNNEL_DST], MAX_NEW_LABELS,
+ &tun_encap_info->labels, tun_encap_info->label);
+ if (ret)
+ goto errout;
+ newts->type = LWTUNNEL_ENCAP_MPLS;
+ newts->flags |= LWTUNNEL_STATE_OUTPUT_REDIRECT;
+
+ *ts = newts;
+
+ return 0;
+
+errout:
+ kfree(newts);
+ *ts = NULL;
+
+ return ret;
+}
+
+static int mpls_fill_encap_info(struct sk_buff *skb,
+ struct lwtunnel_state *lwtstate)
+{
+ struct mpls_iptunnel_encap *tun_encap_info;
+
+ tun_encap_info = mpls_lwtunnel_encap(lwtstate);
+
+ if (nla_put_labels(skb, MPLS_IPTUNNEL_DST, tun_encap_info->labels,
+ tun_encap_info->label))
+ goto nla_put_failure;
+
+ return 0;
+
+nla_put_failure:
+ return -EMSGSIZE;
+}
+
+static int mpls_encap_nlsize(struct lwtunnel_state *lwtstate)
+{
+ struct mpls_iptunnel_encap *tun_encap_info;
+
+ tun_encap_info = mpls_lwtunnel_encap(lwtstate);
+
+ return nla_total_size(tun_encap_info->labels * 4);
+}
+
+static int mpls_encap_cmp(struct lwtunnel_state *a, struct lwtunnel_state *b)
+{
+ struct mpls_iptunnel_encap *a_hdr = mpls_lwtunnel_encap(a);
+ struct mpls_iptunnel_encap *b_hdr = mpls_lwtunnel_encap(b);
+ int l;
+
+ if (a_hdr->labels != b_hdr->labels)
+ return 1;
+
+ for (l = 0; l < MAX_NEW_LABELS; l++)
+ if (a_hdr->label[l] != b_hdr->label[l])
+ return 1;
+ return 0;
+}
+
+static const struct lwtunnel_encap_ops mpls_iptun_ops = {
+ .build_state = mpls_build_state,
+ .output = mpls_output,
+ .fill_encap = mpls_fill_encap_info,
+ .get_encap_size = mpls_encap_nlsize,
+ .cmp_encap = mpls_encap_cmp,
+};
+
+static int __init mpls_iptunnel_init(void)
+{
+ return lwtunnel_encap_add_ops(&mpls_iptun_ops, LWTUNNEL_ENCAP_MPLS);
+}
+module_init(mpls_iptunnel_init);
+
+static void __exit mpls_iptunnel_exit(void)
+{
+ lwtunnel_encap_del_ops(&mpls_iptun_ops, LWTUNNEL_ENCAP_MPLS);
+}
+module_exit(mpls_iptunnel_exit);
+
+MODULE_DESCRIPTION("MultiProtocol Label Switching IP Tunnels");
+MODULE_LICENSE("GPL v2");
