[IPV6] MIP6: Add receiving mobility header functions through raw socket.

Like ICMPv6, mobility header is handled through raw socket.
In inbound case, check only whether ICMPv6 error should be sent as a reply
or not by kernel.
Based on MIPL2 kernel patch.

This patch was also written by: Ville Nuorvala <vnuorval@tcs.hut.fi>
This patch was also written by: Antti Tuominen <anttit@tcs.hut.fi>

Signed-off-by: Masahide NAKAMURA <nakam@linux-ipv6.org>
Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 83 insertions, 0 deletions

diff --git a/net/ipv6/mip6.c b/net/ipv6/mip6.c
index a8adf891fe0e..7b5f89321482 100644
--- a/net/ipv6/mip6.c
+++ b/net/ipv6/mip6.c
@@ -26,7 +26,10 @@
 #include <linux/module.h>
 #include <linux/skbuff.h>
 #include <linux/ipv6.h>
+#include <linux/icmpv6.h>
+#include <net/sock.h>
 #include <net/ipv6.h>
+#include <net/ip6_checksum.h>
 #include <net/xfrm.h>
 #include <net/mip6.h>
 
@@ -55,6 +58,86 @@ static inline void *mip6_padn(__u8 *data, __u8 padlen)
         return data + padlen;
 }
 
+static inline void mip6_param_prob(struct sk_buff *skb, int code, int pos)
+{
+        icmpv6_send(skb, ICMPV6_PARAMPROB, code, pos, skb->dev);
+}
+
+static int mip6_mh_len(int type)
+{
+        int len = 0;
+
+        switch (type) {
+        case IP6_MH_TYPE_BRR:
+                len = 0;
+                break;
+        case IP6_MH_TYPE_HOTI:
+        case IP6_MH_TYPE_COTI:
+        case IP6_MH_TYPE_BU:
+        case IP6_MH_TYPE_BACK:
+                len = 1;
+                break;
+        case IP6_MH_TYPE_HOT:
+        case IP6_MH_TYPE_COT:
+        case IP6_MH_TYPE_BERROR:
+                len = 2;
+                break;
+        }
+        return len;
+}
+
+int mip6_mh_filter(struct sock *sk, struct sk_buff *skb)
+{
+        struct ip6_mh *mh;
+        int mhlen;
+
+        if (!pskb_may_pull(skb, (skb->h.raw - skb->data) + 8) ||
+            !pskb_may_pull(skb, (skb->h.raw - skb->data) + ((skb->h.raw[1] + 1) << 3)))
+                return -1;
+
+        mh = (struct ip6_mh *)skb->h.raw;
+
+        if (mh->ip6mh_hdrlen < mip6_mh_len(mh->ip6mh_type)) {
+                LIMIT_NETDEBUG(KERN_DEBUG "mip6: MH message too short: %d vs >=%d\n",
+                               mh->ip6mh_hdrlen, mip6_mh_len(mh->ip6mh_type));
+                mip6_param_prob(skb, 0, (&mh->ip6mh_hdrlen) - skb->nh.raw);
+                return -1;
+        }
+        mhlen = (mh->ip6mh_hdrlen + 1) << 3;
+
+        if (skb->ip_summed == CHECKSUM_COMPLETE) {
+                skb->ip_summed = CHECKSUM_UNNECESSARY;
+                if (csum_ipv6_magic(&skb->nh.ipv6h->saddr,
+                                    &skb->nh.ipv6h->daddr,
+                                    mhlen, IPPROTO_MH,
+                                    skb->csum)) {
+                        LIMIT_NETDEBUG(KERN_DEBUG "mip6: MH hw checksum failed\n");
+                        skb->ip_summed = CHECKSUM_NONE;
+                }
+        }
+        if (skb->ip_summed == CHECKSUM_NONE) {
+                if (csum_ipv6_magic(&skb->nh.ipv6h->saddr,
+                                    &skb->nh.ipv6h->daddr,
+                                    mhlen, IPPROTO_MH,
+                                    skb_checksum(skb, 0, mhlen, 0))) {
+                        LIMIT_NETDEBUG(KERN_DEBUG "mip6: MH checksum failed [%04x:%04x:%04x:%04x:%04x:%04x:%04x:%04x > %04x:%04x:%04x:%04x:%04x:%04x:%04x:%04x]\n",
+                                       NIP6(skb->nh.ipv6h->saddr),
+                                       NIP6(skb->nh.ipv6h->daddr));
+                        return -1;
+                }
+                skb->ip_summed = CHECKSUM_UNNECESSARY;
+        }
+
+        if (mh->ip6mh_proto != IPPROTO_NONE) {
+                LIMIT_NETDEBUG(KERN_DEBUG "mip6: MH invalid payload proto = %d\n",
+                               mh->ip6mh_proto);
+                mip6_param_prob(skb, 0, (&mh->ip6mh_proto) - skb->nh.raw);
+                return -1;
+        }
+
+        return 0;
+}
+
 static int mip6_destopt_input(struct xfrm_state *x, struct sk_buff *skb)
 {
         struct ipv6hdr *iph = skb->nh.ipv6h;