[IPV6]: Add RFC4214 support

This patch includes support for the Intra-Site Automatic Tunnel
Addressing Protocol (ISATAP) per RFC4214. It uses the SIT
module, and is configured using extensions to the "iproute2"
utility. The diffs are specific to the Linux 2.6.24-rc2 kernel
distribution.

This version includes the diff for ./include/linux/if.h which was
missing in the v2.4 submission and is needed to make the
patch compile. The patch has been installed, compiled and
tested in a clean 2.6.24-rc2 kernel build area.

Signed-off-by: Fred L. Templin <fred.l.templin@boeing.com>
Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

7 files changed, 131 insertions, 1 deletions

diff --git a/include/linux/if.h b/include/linux/if.h
index 186070d5c544..5c9d1fa93fef 100644
--- a/include/linux/if.h
+++ b/include/linux/if.h
@@ -63,6 +63,7 @@
 #define IFF_MASTER_ALB  0x10            /* bonding master, balance-alb. */
 #define IFF_BONDING     0x20            /* bonding master or slave      */
 #define IFF_SLAVE_NEEDARP 0x40          /* need ARPs for validation     */
+#define IFF_ISATAP      0x80            /* ISATAP interface (RFC4214)   */
 
 #define IF_GET_IFACE    0x0001          /* for querying only */
 #define IF_GET_PROTO    0x0002
diff --git a/include/linux/if_tunnel.h b/include/linux/if_tunnel.h
index 660b5010c2d9..228eb4eb3129 100644
--- a/include/linux/if_tunnel.h
+++ b/include/linux/if_tunnel.h
@@ -17,6 +17,9 @@
 #define GRE_FLAGS       __constant_htons(0x00F8)
 #define GRE_VERSION     __constant_htons(0x0007)
 
+/* i_flags values for SIT mode */
+#define SIT_ISATAP      0x0001
+
 struct ip_tunnel_parm
 {
         char                    name[IFNAMSIZ];
diff --git a/include/linux/in.h b/include/linux/in.h
index 3975cbf52f20..a8f00cac8f79 100644
--- a/include/linux/in.h
+++ b/include/linux/in.h
@@ -253,6 +253,14 @@ struct sockaddr_in {
 #define ZERONET(x)      (((x) & htonl(0xff000000)) == htonl(0x00000000))
 #define LOCAL_MCAST(x)  (((x) & htonl(0xFFFFFF00)) == htonl(0xE0000000))
 
+/* Special-Use IPv4 Addresses (RFC3330) */
+#define PRIVATE_10(x)   (((x) & htonl(0xff000000)) == htonl(0x0A000000))
+#define LINKLOCAL_169(x) (((x) & htonl(0xffff0000)) == htonl(0xA9FE0000))
+#define PRIVATE_172(x)  (((x) & htonl(0xfff00000)) == htonl(0xAC100000))
+#define TEST_192(x)     (((x) & htonl(0xffffff00)) == htonl(0xC0000200))
+#define ANYCAST_6TO4(x) (((x) & htonl(0xffffff00)) == htonl(0xC0586300))
+#define PRIVATE_192(x)  (((x) & htonl(0xffff0000)) == htonl(0xC0A80000))
+#define TEST_198(x)     (((x) & htonl(0xfffe0000)) == htonl(0xC6120000))
 #endif
 
 #endif  /* _LINUX_IN_H */
diff --git a/include/net/addrconf.h b/include/net/addrconf.h
index bccc2feb99da..c56827da0dee 100644
--- a/include/net/addrconf.h
+++ b/include/net/addrconf.h
@@ -17,6 +17,7 @@
 
 #define IPV6_MAX_ADDRESSES              16
 
+#include <linux/in.h>
 #include <linux/in6.h>
 
 struct prefix_info {
@@ -249,6 +250,24 @@ static inline int ipv6_addr_is_ll_all_routers(const struct in6_addr *addr)
                 addr->s6_addr32[3] == htonl(0x00000002));
 }
 
+static inline int ipv6_isatap_eui64(u8 *eui, __be32 addr)
+{
+        eui[0] = (ZERONET(addr) || PRIVATE_10(addr) || LOOPBACK(addr) ||
+                  LINKLOCAL_169(addr) || PRIVATE_172(addr) || TEST_192(addr) ||
+                  ANYCAST_6TO4(addr) || PRIVATE_192(addr) || TEST_198(addr) ||
+                  MULTICAST(addr) || BADCLASS(addr)) ? 0x00 : 0x02;
+        eui[1] = 0;
+        eui[2] = 0x5E;
+        eui[3] = 0xFE;
+        memcpy (eui+4, &addr, 4);
+        return 0;
+}
+
+static inline int ipv6_addr_is_isatap(const struct in6_addr *addr)
+{
+        return ((addr->s6_addr32[2] | htonl(0x02000000)) == htonl(0x02005EFE));
+}
+
 #ifdef CONFIG_PROC_FS
 extern int if6_proc_init(void);
 extern void if6_proc_exit(void);
diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index 6c8b193474ba..f177424c186f 100644
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -377,6 +377,13 @@ static struct inet6_dev * ipv6_add_dev(struct net_device *dev)
                        "%s: Disabled Privacy Extensions\n",
                        dev->name);
                 ndev->cnf.use_tempaddr = -1;
+
+                if (dev->type == ARPHRD_SIT && (dev->priv_flags & IFF_ISATAP)) {
+                        printk(KERN_INFO
+                               "%s: Disabled Multicast RS\n",
+                               dev->name);
+                        ndev->cnf.rtr_solicits = 0;
+                }
         } else {
                 in6_dev_hold(ndev);
                 ipv6_regen_rndid((unsigned long) ndev);
@@ -1409,6 +1416,9 @@ static int ipv6_generate_eui64(u8 *eui, struct net_device *dev)
                 return addrconf_ifid_arcnet(eui, dev);
         case ARPHRD_INFINIBAND:
                 return addrconf_ifid_infiniband(eui, dev);
+        case ARPHRD_SIT:
+                if (dev->priv_flags & IFF_ISATAP)
+                        return ipv6_isatap_eui64(eui, *(__be32 *)dev->dev_addr);
         }
         return -1;
 }
@@ -1444,7 +1454,7 @@ regen:
          *
          *  - Reserved subnet anycast (RFC 2526)
          *      11111101 11....11 1xxxxxxx
-         *  - ISATAP (draft-ietf-ngtrans-isatap-13.txt) 5.1
+         *  - ISATAP (RFC4214) 6.1
          *      00-00-5E-FE-xx-xx-xx-xx
          *  - value 0
          *  - XXX: already assigned to an address on the device
@@ -2175,6 +2185,16 @@ static void addrconf_sit_config(struct net_device *dev)
                 return;
         }
 
+        if (dev->priv_flags & IFF_ISATAP) {
+                struct in6_addr addr;
+
+                ipv6_addr_set(&addr,  htonl(0xFE800000), 0, 0, 0);
+                addrconf_prefix_route(&addr, 64, dev, 0, 0);
+                if (!ipv6_generate_eui64(addr.s6_addr + 8, dev))
+                        addrconf_add_linklocal(idev, &addr);
+                return;
+        }
+
         sit_add_v4_addrs(idev);
 
         if (dev->flags&IFF_POINTOPOINT) {
diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index d7ec4c9ffc4b..e2c980dbe52d 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -1659,6 +1659,8 @@ struct rt6_info *rt6_get_dflt_router(struct in6_addr *addr, struct net_device *d
         return rt;
 }
 
+EXPORT_SYMBOL(rt6_get_dflt_router);
+
 struct rt6_info *rt6_add_dflt_router(struct in6_addr *gwaddr,
                                      struct net_device *dev,
                                      unsigned int pref)
diff --git a/net/ipv6/sit.c b/net/ipv6/sit.c
index 71433d29d884..b3b8513e9cb7 100644
--- a/net/ipv6/sit.c
+++ b/net/ipv6/sit.c
@@ -16,6 +16,7 @@
  *      Changes:
  * Roger Venning <r.venning@telstra.com>:       6to4 support
  * Nate Thompson <nate@thebog.net>:             6to4 support
+ * Fred L. Templin <fltemplin@acm.org>:         isatap support
  */
 
 #include <linux/module.h>
@@ -182,6 +183,9 @@ static struct ip_tunnel * ipip6_tunnel_locate(struct ip_tunnel_parm *parms, int
         dev->init = ipip6_tunnel_init;
         nt->parms = *parms;
 
+        if (parms->i_flags & SIT_ISATAP)
+                dev->priv_flags |= IFF_ISATAP;
+
         if (register_netdevice(dev) < 0) {
                 free_netdev(dev);
                 goto failed;
@@ -364,6 +368,48 @@ static inline void ipip6_ecn_decapsulate(struct iphdr *iph, struct sk_buff *skb)
                 IP6_ECN_set_ce(ipv6_hdr(skb));
 }
 
+/* ISATAP (RFC4214) - check source address */
+static int
+isatap_srcok(struct sk_buff *skb, struct iphdr *iph, struct net_device *dev)
+{
+        struct neighbour *neigh;
+        struct dst_entry *dst;
+        struct rt6_info *rt;
+        struct flowi fl;
+        struct in6_addr *addr6;
+        struct in6_addr rtr;
+        struct ipv6hdr *iph6;
+        int ok = 0;
+
+        /* from onlink default router */
+        ipv6_addr_set(&rtr,  htonl(0xFE800000), 0, 0, 0);
+        ipv6_isatap_eui64(rtr.s6_addr + 8, iph->saddr);
+        if ((rt = rt6_get_dflt_router(&rtr, dev))) {
+                dst_release(&rt->u.dst);
+                return 1;
+        }
+
+        iph6 = ipv6_hdr(skb);
+        memset(&fl, 0, sizeof(fl));
+        fl.proto = iph6->nexthdr;
+        ipv6_addr_copy(&fl.fl6_dst, &iph6->saddr);
+        fl.oif = dev->ifindex;
+        security_skb_classify_flow(skb, &fl);
+
+        dst = ip6_route_output(NULL, &fl);
+        if (!dst->error && (dst->dev == dev) && (neigh = dst->neighbour)) {
+
+                addr6 = (struct in6_addr*)&neigh->primary_key;
+
+                /* from correct previous hop */
+                if (ipv6_addr_is_isatap(addr6) &&
+                    (addr6->s6_addr32[3] == iph->saddr))
+                        ok = 1;
+        }
+        dst_release(dst);
+        return ok;
+}
+
 static int ipip6_rcv(struct sk_buff *skb)
 {
         struct iphdr *iph;
@@ -382,6 +428,14 @@ static int ipip6_rcv(struct sk_buff *skb)
                 IPCB(skb)->flags = 0;
                 skb->protocol = htons(ETH_P_IPV6);
                 skb->pkt_type = PACKET_HOST;
+
+                if ((tunnel->dev->priv_flags & IFF_ISATAP) &&
+                    !isatap_srcok(skb, iph, tunnel->dev)) {
+                        tunnel->stat.rx_errors++;
+                        read_unlock(&ipip6_lock);
+                        kfree_skb(skb);
+                        return 0;
+                }
                 tunnel->stat.rx_packets++;
                 tunnel->stat.rx_bytes += skb->len;
                 skb->dev = tunnel->dev;
@@ -444,6 +498,29 @@ static int ipip6_tunnel_xmit(struct sk_buff *skb, struct net_device *dev)
         if (skb->protocol != htons(ETH_P_IPV6))
                 goto tx_error;
 
+        /* ISATAP (RFC4214) - must come before 6to4 */
+        if (dev->priv_flags & IFF_ISATAP) {
+                struct neighbour *neigh = NULL;
+
+                if (skb->dst)
+                        neigh = skb->dst->neighbour;
+
+                if (neigh == NULL) {
+                        if (net_ratelimit())
+                                printk(KERN_DEBUG "sit: nexthop == NULL\n");
+                        goto tx_error;
+                }
+
+                addr6 = (struct in6_addr*)&neigh->primary_key;
+                addr_type = ipv6_addr_type(addr6);
+
+                if ((addr_type & IPV6_ADDR_UNICAST) &&
+                     ipv6_addr_is_isatap(addr6))
+                        dst = addr6->s6_addr32[3];
+                else
+                        goto tx_error;
+        }
+
         if (!dst)
                 dst = try_6to4(&iph6->daddr);