[IPV6] IPSEC: Support sending with Mobile IPv6 extension headers.

Mobile IPv6 defines home address option as an option of destination
options header. It is placed before fragment header then
ip6_find_1stfragopt() is fixed to know about it.

Home address option also carries final source address of the flow,
then outbound AH calculation should take care of it like routing
header case.  Based on MIPL2 kernel patch.
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>

net/ipv6/ah6.c

@@ -74,6 +74,68 @@ bad:
 	return 0;
 }
 
+#ifdef CONFIG_IPV6_MIP6
+/**
+ *	ipv6_rearrange_destopt - rearrange IPv6 destination options header
+ *	@iph: IPv6 header
+ *	@destopt: destionation options header
+ */
+static void ipv6_rearrange_destopt(struct ipv6hdr *iph, struct ipv6_opt_hdr *destopt)
+{
+	u8 *opt = (u8 *)destopt;
+	int len = ipv6_optlen(destopt);
+	int off = 0;
+	int optlen = 0;
+
+	off += 2;
+	len -= 2;
+
+	while (len > 0) {
+
+		switch (opt[off]) {
+
+		case IPV6_TLV_PAD0:
+			optlen = 1;
+			break;
+		default:
+			if (len < 2)
+				goto bad;
+			optlen = opt[off+1]+2;
+			if (len < optlen)
+				goto bad;
+
+			/* Rearrange the source address in @iph and the
+			 * addresses in home address option for final source.
+			 * See 11.3.2 of RFC 3775 for details.
+			 */
+			if (opt[off] == IPV6_TLV_HAO) {
+				struct in6_addr final_addr;
+				struct ipv6_destopt_hao *hao;
+
+				hao = (struct ipv6_destopt_hao *)&opt[off];
+				if (hao->length != sizeof(hao->addr)) {
+					if (net_ratelimit())
+						printk(KERN_WARNING "destopt hao: invalid header length: %u\n", hao->length);
+					goto bad;
+				}
+				ipv6_addr_copy(&final_addr, &hao->addr);
+				ipv6_addr_copy(&hao->addr, &iph->saddr);
+				ipv6_addr_copy(&iph->saddr, &final_addr);
+			}
+			break;
+		}
+
+		off += optlen;
+		len -= optlen;
+	}
+	if (len == 0)
+		return;
+
+bad:
+	return;
+}
+#endif
+
 /**
  *	ipv6_rearrange_rthdr - rearrange IPv6 routing header
  *	@iph: IPv6 header
@@ -113,7 +175,11 @@ static void ipv6_rearrange_rthdr(struct ipv6hdr *iph, struct ipv6_rt_hdr *rthdr)
 	ipv6_addr_copy(&iph->daddr, &final_addr);
 }
 
+#ifdef CONFIG_IPV6_MIP6
+static int ipv6_clear_mutable_options(struct ipv6hdr *iph, int len, int dir)
+#else
 static int ipv6_clear_mutable_options(struct ipv6hdr *iph, int len)
+#endif
 {
 	union {
 		struct ipv6hdr *iph;
@@ -128,6 +194,28 @@ static int ipv6_clear_mutable_options(struct ipv6hdr *iph, int len)
 
 	while (exthdr.raw < end) {
 		switch (nexthdr) {
+#ifdef CONFIG_IPV6_MIP6
+		case NEXTHDR_HOP:
+			if (!zero_out_mutable_opts(exthdr.opth)) {
+				LIMIT_NETDEBUG(
+					KERN_WARNING "overrun %sopts\n",
+					nexthdr == NEXTHDR_HOP ?
+						"hop" : "dest");
+				return -EINVAL;
+			}
+			break;
+		case NEXTHDR_DEST:
+			if (dir == XFRM_POLICY_OUT)
+				ipv6_rearrange_destopt(iph, exthdr.opth);
+			if (!zero_out_mutable_opts(exthdr.opth)) {
+				LIMIT_NETDEBUG(
+					KERN_WARNING "overrun %sopts\n",
+					nexthdr == NEXTHDR_HOP ?
+						"hop" : "dest");
+				return -EINVAL;
+			}
+			break;
+#else
 		case NEXTHDR_HOP:
 		case NEXTHDR_DEST:
 			if (!zero_out_mutable_opts(exthdr.opth)) {
@@ -138,6 +226,7 @@ static int ipv6_clear_mutable_options(struct ipv6hdr *iph, int len)
 				return -EINVAL;
 			}
 			break;
+#endif
 
 		case NEXTHDR_ROUTING:
 			ipv6_rearrange_rthdr(iph, exthdr.rth);
@@ -164,6 +253,9 @@ static int ah6_output(struct xfrm_state *x, struct sk_buff *skb)
 	u8 nexthdr;
 	char tmp_base[8];
 	struct {
+#ifdef CONFIG_IPV6_MIP6
+		struct in6_addr saddr;
+#endif
 		struct in6_addr daddr;
 		char hdrs[0];
 	} *tmp_ext;
@@ -188,10 +280,18 @@ static int ah6_output(struct xfrm_state *x, struct sk_buff *skb)
 			err = -ENOMEM;
 			goto error;
 		}
+#ifdef CONFIG_IPV6_MIP6
+		memcpy(tmp_ext, &top_iph->saddr, extlen);
+		err = ipv6_clear_mutable_options(top_iph,
+						 extlen - sizeof(*tmp_ext) +
+						 sizeof(*top_iph),
+						 XFRM_POLICY_OUT);
+#else
 		memcpy(tmp_ext, &top_iph->daddr, extlen);
 		err = ipv6_clear_mutable_options(top_iph,
 						 extlen - sizeof(*tmp_ext) +
 						 sizeof(*top_iph));
+#endif
 		if (err)
 			goto error_free_iph;
 	}
@@ -222,7 +322,11 @@ static int ah6_output(struct xfrm_state *x, struct sk_buff *skb)
 
 	memcpy(top_iph, tmp_base, sizeof(tmp_base));
 	if (tmp_ext) {
+#ifdef CONFIG_IPV6_MIP6
+		memcpy(&top_iph->saddr, tmp_ext, extlen);
+#else
 		memcpy(&top_iph->daddr, tmp_ext, extlen);
+#endif
 error_free_iph:
 		kfree(tmp_ext);
 	}
@@ -282,8 +386,13 @@ static int ah6_input(struct xfrm_state *x, struct sk_buff *skb)
 	if (!tmp_hdr)
 		goto out;
 	memcpy(tmp_hdr, skb->nh.raw, hdr_len);
+#ifdef CONFIG_IPV6_MIP6
+	if (ipv6_clear_mutable_options(skb->nh.ipv6h, hdr_len, XFRM_POLICY_IN))
+		goto free_out;
+#else
 	if (ipv6_clear_mutable_options(skb->nh.ipv6h, hdr_len))
 		goto free_out;
+#endif
 	skb->nh.ipv6h->priority    = 0;
 	skb->nh.ipv6h->flow_lbl[0] = 0;
 	skb->nh.ipv6h->flow_lbl[1] = 0;

net/ipv6/ip6_output.c

@@ -475,17 +475,25 @@ int ip6_find_1stfragopt(struct sk_buff *skb, u8 **nexthdr)
 		switch (**nexthdr) {
 
 		case NEXTHDR_HOP:
+			break;
 		case NEXTHDR_ROUTING:
+			found_rhdr = 1;
+			break;
 		case NEXTHDR_DEST:
-			if (**nexthdr == NEXTHDR_ROUTING) found_rhdr = 1;
-			if (**nexthdr == NEXTHDR_DEST && found_rhdr) return offset;
-			offset += ipv6_optlen(exthdr);
-			*nexthdr = &exthdr->nexthdr;
-			exthdr = (struct ipv6_opt_hdr*)(skb->nh.raw + offset);
+#ifdef CONFIG_IPV6_MIP6
+			if (ipv6_find_tlv(skb, offset, IPV6_TLV_HAO) >= 0)
+				break;
+#endif
+			if (found_rhdr)
+				return offset;
 			break;
 		default :
 			return offset;
 		}
+
+		offset += ipv6_optlen(exthdr);
+		*nexthdr = &exthdr->nexthdr;
+		exthdr = (struct ipv6_opt_hdr*)(skb->nh.raw + offset);
 	}
 
 	return offset;