GRE: Refactor GRE tunneling code.

Following patch refactors GRE code into ip tunneling code and GRE
specific code. Common tunneling code is moved to ip_tunnel module.
ip_tunnel module is written as generic library which can be used
by different tunneling implementations.

ip_tunnel module contains following components:
 - packet xmit and rcv generic code. xmit flow looks like
   (gre_xmit/ipip_xmit)->ip_tunnel_xmit->ip_local_out.
 - hash table of all devices.
 - lookup for tunnel devices.
 - control plane operations like device create, destroy, ioctl, netlink
   operations code.
 - registration for tunneling modules, like gre, ipip etc.
 - define single pcpu_tstats dev->tstats.
 - struct tnl_ptk_info added to pass parsed tunnel packet parameters.

ipip.h header is renamed to ip_tunnel.h

Signed-off-by: Pravin B Shelar <pshelar@nicira.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 177 insertions, 0 deletions

diff --git a/include/net/ip_tunnels.h b/include/net/ip_tunnels.h
new file mode 100644
index 000000000000..4b6f0b28f41f
--- /dev/null
+++ b/include/net/ip_tunnels.h
@@ -0,0 +1,177 @@
+#ifndef __NET_IP_TUNNELS_H
+#define __NET_IP_TUNNELS_H 1
+
+#include <linux/if_tunnel.h>
+#include <linux/netdevice.h>
+#include <linux/skbuff.h>
+#include <linux/types.h>
+#include <linux/u64_stats_sync.h>
+#include <net/dsfield.h>
+#include <net/gro_cells.h>
+#include <net/inet_ecn.h>
+#include <net/ip.h>
+#include <net/rtnetlink.h>
+
+#if IS_ENABLED(CONFIG_IPV6)
+#include <net/ipv6.h>
+#include <net/ip6_fib.h>
+#include <net/ip6_route.h>
+#endif
+
+/* Keep error state on tunnel for 30 sec */
+#define IPTUNNEL_ERR_TIMEO      (30*HZ)
+
+/* 6rd prefix/relay information */
+#ifdef CONFIG_IPV6_SIT_6RD
+struct ip_tunnel_6rd_parm {
+        struct in6_addr         prefix;
+        __be32                  relay_prefix;
+        u16                     prefixlen;
+        u16                     relay_prefixlen;
+};
+#endif
+
+struct ip_tunnel_prl_entry {
+        struct ip_tunnel_prl_entry __rcu *next;
+        __be32                          addr;
+        u16                             flags;
+        struct rcu_head                 rcu_head;
+};
+
+struct ip_tunnel {
+        struct ip_tunnel __rcu  *next;
+        struct hlist_node hash_node;
+        struct net_device       *dev;
+
+        int             err_count;      /* Number of arrived ICMP errors */
+        unsigned long   err_time;       /* Time when the last ICMP error
+                                         * arrived */
+
+        /* These four fields used only by GRE */
+        __u32           i_seqno;        /* The last seen seqno  */
+        __u32           o_seqno;        /* The last output seqno */
+        int             hlen;           /* Precalculated header length */
+        int             mlink;
+
+        struct ip_tunnel_parm parms;
+
+        /* for SIT */
+#ifdef CONFIG_IPV6_SIT_6RD
+        struct ip_tunnel_6rd_parm ip6rd;
+#endif
+        struct ip_tunnel_prl_entry __rcu *prl;  /* potential router list */
+        unsigned int            prl_count;      /* # of entries in PRL */
+        int                     ip_tnl_net_id;
+        struct gro_cells        gro_cells;
+};
+
+#define TUNNEL_CSUM     __cpu_to_be16(0x01)
+#define TUNNEL_ROUTING  __cpu_to_be16(0x02)
+#define TUNNEL_KEY      __cpu_to_be16(0x04)
+#define TUNNEL_SEQ      __cpu_to_be16(0x08)
+#define TUNNEL_STRICT   __cpu_to_be16(0x10)
+#define TUNNEL_REC      __cpu_to_be16(0x20)
+#define TUNNEL_VERSION  __cpu_to_be16(0x40)
+#define TUNNEL_NO_KEY   __cpu_to_be16(0x80)
+
+struct tnl_ptk_info {
+        __be16 flags;
+        __be16 proto;
+        __be32 key;
+        __be32 seq;
+};
+
+#define PACKET_RCVD     0
+#define PACKET_REJECT   1
+
+#define IP_TNL_HASH_BITS   10
+#define IP_TNL_HASH_SIZE   (1 << IP_TNL_HASH_BITS)
+
+struct ip_tunnel_net {
+        struct hlist_head *tunnels;
+        struct net_device *fb_tunnel_dev;
+};
+
+int ip_tunnel_init(struct net_device *dev);
+void ip_tunnel_uninit(struct net_device *dev);
+void  ip_tunnel_dellink(struct net_device *dev, struct list_head *head);
+int __net_init ip_tunnel_init_net(struct net *net, int ip_tnl_net_id,
+                                  struct rtnl_link_ops *ops, char *devname);
+
+void __net_exit ip_tunnel_delete_net(struct ip_tunnel_net *itn);
+
+void ip_tunnel_xmit(struct sk_buff *skb, struct net_device *dev,
+                    const struct iphdr *tnl_params);
+int ip_tunnel_ioctl(struct net_device *dev, struct ip_tunnel_parm *p, int cmd);
+int ip_tunnel_change_mtu(struct net_device *dev, int new_mtu);
+
+struct rtnl_link_stats64 *ip_tunnel_get_stats64(struct net_device *dev,
+                                                struct rtnl_link_stats64 *tot);
+struct ip_tunnel *ip_tunnel_lookup(struct ip_tunnel_net *itn,
+                                   int link, __be16 flags,
+                                   __be32 remote, __be32 local,
+                                   __be32 key);
+
+int ip_tunnel_rcv(struct ip_tunnel *tunnel, struct sk_buff *skb,
+                  const struct tnl_ptk_info *tpi, bool log_ecn_error);
+int ip_tunnel_changelink(struct net_device *dev, struct nlattr *tb[],
+                         struct ip_tunnel_parm *p);
+int ip_tunnel_newlink(struct net_device *dev, struct nlattr *tb[],
+                      struct ip_tunnel_parm *p);
+void ip_tunnel_setup(struct net_device *dev, int net_id);
+
+/* Extract dsfield from inner protocol */
+static inline u8 ip_tunnel_get_dsfield(const struct iphdr *iph,
+                                       const struct sk_buff *skb)
+{
+        if (skb->protocol == htons(ETH_P_IP))
+                return iph->tos;
+        else if (skb->protocol == htons(ETH_P_IPV6))
+                return ipv6_get_dsfield((const struct ipv6hdr *)iph);
+        else
+                return 0;
+}
+
+/* Propogate ECN bits out */
+static inline u8 ip_tunnel_ecn_encap(u8 tos, const struct iphdr *iph,
+                                     const struct sk_buff *skb)
+{
+        u8 inner = ip_tunnel_get_dsfield(iph, skb);
+
+        return INET_ECN_encapsulate(tos, inner);
+}
+
+static inline void tunnel_ip_select_ident(struct sk_buff *skb,
+                                          const struct iphdr  *old_iph,
+                                          struct dst_entry *dst)
+{
+        struct iphdr *iph = ip_hdr(skb);
+
+        /* Use inner packet iph-id if possible. */
+        if (skb->protocol == htons(ETH_P_IP) && old_iph->id)
+                iph->id = old_iph->id;
+        else
+                __ip_select_ident(iph, dst,
+                                  (skb_shinfo(skb)->gso_segs ?: 1) - 1);
+}
+
+static inline void iptunnel_xmit(struct sk_buff *skb, struct net_device *dev)
+{
+        int err;
+        int pkt_len = skb->len - skb_transport_offset(skb);
+        struct pcpu_tstats *tstats = this_cpu_ptr(dev->tstats);
+
+        nf_reset(skb);
+
+        err = ip_local_out(skb);
+        if (likely(net_xmit_eval(err) == 0)) {
+                u64_stats_update_begin(&tstats->syncp);
+                tstats->tx_bytes += pkt_len;
+                tstats->tx_packets++;
+                u64_stats_update_end(&tstats->syncp);
+        } else {
+                dev->stats.tx_errors++;
+                dev->stats.tx_aborted_errors++;
+        }
+}
+#endif /* __NET_IP_TUNNELS_H */