1 files changed, 410 insertions, 0 deletions
diff --git a/net/ipv6/mip6.c b/net/ipv6/mip6.c
new file mode 100644
index 000000000..83d2a8be2
--- /dev/null
+++ b/net/ipv6/mip6.c
@@ -0,0 +1,410 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (C)2003-2006 Helsinki University of Technology
+ * Copyright (C)2003-2006 USAGI/WIDE Project
+ */
+/*
+ * Authors:
+ *	Noriaki TAKAMIYA @USAGI
+ *	Masahide NAKAMURA @USAGI
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/module.h>
+#include <linux/skbuff.h>
+#include <linux/time.h>
+#include <linux/ipv6.h>
+#include <linux/icmpv6.h>
+#include <net/sock.h>
+#include <net/ipv6.h>
+#include <net/ip6_checksum.h>
+#include <net/rawv6.h>
+#include <net/xfrm.h>
+#include <net/mip6.h>
+
+static inline unsigned int calc_padlen(unsigned int len, unsigned int n)
+{
+	return (n - len + 16) & 0x7;
+}
+
+static inline void *mip6_padn(__u8 *data, __u8 padlen)
+{
+	if (!data)
+		return NULL;
+	if (padlen == 1) {
+		data[0] = IPV6_TLV_PAD1;
+	} else if (padlen > 1) {
+		data[0] = IPV6_TLV_PADN;
+		data[1] = padlen - 2;
+		if (padlen > 2)
+			memset(data+2, 0, data[1]);
+	}
+	return data + padlen;
+}
+
+static inline void mip6_param_prob(struct sk_buff *skb, u8 code, int pos)
+{
+	icmpv6_send(skb, ICMPV6_PARAMPROB, code, pos);
+}
+
+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;
+}
+
+static int mip6_mh_filter(struct sock *sk, struct sk_buff *skb)
+{
+	struct ip6_mh _hdr;
+	const struct ip6_mh *mh;
+
+	mh = skb_header_pointer(skb, skb_transport_offset(skb),
+				sizeof(_hdr), &_hdr);
+	if (!mh)
+		return -1;
+
+	if (((mh->ip6mh_hdrlen + 1) << 3) > skb->len)
+		return -1;
+
+	if (mh->ip6mh_hdrlen < mip6_mh_len(mh->ip6mh_type)) {
+		net_dbg_ratelimited("mip6: MH message too short: %d vs >=%d\n",
+				    mh->ip6mh_hdrlen,
+				    mip6_mh_len(mh->ip6mh_type));
+		mip6_param_prob(skb, 0, offsetof(struct ip6_mh, ip6mh_hdrlen) +
+				skb_network_header_len(skb));
+		return -1;
+	}
+
+	if (mh->ip6mh_proto != IPPROTO_NONE) {
+		net_dbg_ratelimited("mip6: MH invalid payload proto = %d\n",
+				    mh->ip6mh_proto);
+		mip6_param_prob(skb, 0, offsetof(struct ip6_mh, ip6mh_proto) +
+				skb_network_header_len(skb));
+		return -1;
+	}
+
+	return 0;
+}
+
+struct mip6_report_rate_limiter {
+	spinlock_t lock;
+	ktime_t stamp;
+	int iif;
+	struct in6_addr src;
+	struct in6_addr dst;
+};
+
+static struct mip6_report_rate_limiter mip6_report_rl = {
+	.lock = __SPIN_LOCK_UNLOCKED(mip6_report_rl.lock)
+};
+
+static int mip6_destopt_input(struct xfrm_state *x, struct sk_buff *skb)
+{
+	const struct ipv6hdr *iph = ipv6_hdr(skb);
+	struct ipv6_destopt_hdr *destopt = (struct ipv6_destopt_hdr *)skb->data;
+	int err = destopt->nexthdr;
+
+	spin_lock(&x->lock);
+	if (!ipv6_addr_equal(&iph->saddr, (struct in6_addr *)x->coaddr) &&
+	    !ipv6_addr_any((struct in6_addr *)x->coaddr))
+		err = -ENOENT;
+	spin_unlock(&x->lock);
+
+	return err;
+}
+
+/* Destination Option Header is inserted.
+ * IP Header's src address is replaced with Home Address Option in
+ * Destination Option Header.
+ */
+static int mip6_destopt_output(struct xfrm_state *x, struct sk_buff *skb)
+{
+	struct ipv6hdr *iph;
+	struct ipv6_destopt_hdr *dstopt;
+	struct ipv6_destopt_hao *hao;
+	u8 nexthdr;
+	int len;
+
+	skb_push(skb, -skb_network_offset(skb));
+	iph = ipv6_hdr(skb);
+
+	nexthdr = *skb_mac_header(skb);
+	*skb_mac_header(skb) = IPPROTO_DSTOPTS;
+
+	dstopt = (struct ipv6_destopt_hdr *)skb_transport_header(skb);
+	dstopt->nexthdr = nexthdr;
+
+	hao = mip6_padn((char *)(dstopt + 1),
+			calc_padlen(sizeof(*dstopt), 6));
+
+	hao->type = IPV6_TLV_HAO;
+	BUILD_BUG_ON(sizeof(*hao) != 18);
+	hao->length = sizeof(*hao) - 2;
+
+	len = ((char *)hao - (char *)dstopt) + sizeof(*hao);
+
+	memcpy(&hao->addr, &iph->saddr, sizeof(hao->addr));
+	spin_lock_bh(&x->lock);
+	memcpy(&iph->saddr, x->coaddr, sizeof(iph->saddr));
+	spin_unlock_bh(&x->lock);
+
+	WARN_ON(len != x->props.header_len);
+	dstopt->hdrlen = (x->props.header_len >> 3) - 1;
+
+	return 0;
+}
+
+static inline int mip6_report_rl_allow(ktime_t stamp,
+				       const struct in6_addr *dst,
+				       const struct in6_addr *src, int iif)
+{
+	int allow = 0;
+
+	spin_lock_bh(&mip6_report_rl.lock);
+	if (mip6_report_rl.stamp != stamp ||
+	    mip6_report_rl.iif != iif ||
+	    !ipv6_addr_equal(&mip6_report_rl.src, src) ||
+	    !ipv6_addr_equal(&mip6_report_rl.dst, dst)) {
+		mip6_report_rl.stamp = stamp;
+		mip6_report_rl.iif = iif;
+		mip6_report_rl.src = *src;
+		mip6_report_rl.dst = *dst;
+		allow = 1;
+	}
+	spin_unlock_bh(&mip6_report_rl.lock);
+	return allow;
+}
+
+static int mip6_destopt_reject(struct xfrm_state *x, struct sk_buff *skb,
+			       const struct flowi *fl)
+{
+	struct net *net = xs_net(x);
+	struct inet6_skb_parm *opt = (struct inet6_skb_parm *)skb->cb;
+	const struct flowi6 *fl6 = &fl->u.ip6;
+	struct ipv6_destopt_hao *hao = NULL;
+	struct xfrm_selector sel;
+	int offset;
+	ktime_t stamp;
+	int err = 0;
+
+	if (unlikely(fl6->flowi6_proto == IPPROTO_MH &&
+		     fl6->fl6_mh_type <= IP6_MH_TYPE_MAX))
+		goto out;
+
+	if (likely(opt->dsthao)) {
+		offset = ipv6_find_tlv(skb, opt->dsthao, IPV6_TLV_HAO);
+		if (likely(offset >= 0))
+			hao = (struct ipv6_destopt_hao *)
+					(skb_network_header(skb) + offset);
+	}
+
+	stamp = skb_get_ktime(skb);
+
+	if (!mip6_report_rl_allow(stamp, &ipv6_hdr(skb)->daddr,
+				  hao ? &hao->addr : &ipv6_hdr(skb)->saddr,
+				  opt->iif))
+		goto out;
+
+	memset(&sel, 0, sizeof(sel));
+	memcpy(&sel.daddr, (xfrm_address_t *)&ipv6_hdr(skb)->daddr,
+	       sizeof(sel.daddr));
+	sel.prefixlen_d = 128;
+	memcpy(&sel.saddr, (xfrm_address_t *)&ipv6_hdr(skb)->saddr,
+	       sizeof(sel.saddr));
+	sel.prefixlen_s = 128;
+	sel.family = AF_INET6;
+	sel.proto = fl6->flowi6_proto;
+	sel.dport = xfrm_flowi_dport(fl, &fl6->uli);
+	if (sel.dport)
+		sel.dport_mask = htons(~0);
+	sel.sport = xfrm_flowi_sport(fl, &fl6->uli);
+	if (sel.sport)
+		sel.sport_mask = htons(~0);
+	sel.ifindex = fl6->flowi6_oif;
+
+	err = km_report(net, IPPROTO_DSTOPTS, &sel,
+			(hao ? (xfrm_address_t *)&hao->addr : NULL));
+
+ out:
+	return err;
+}
+
+static int mip6_destopt_init_state(struct xfrm_state *x, struct netlink_ext_ack *extack)
+{
+	if (x->id.spi) {
+		NL_SET_ERR_MSG(extack, "SPI must be 0");
+		return -EINVAL;
+	}
+	if (x->props.mode != XFRM_MODE_ROUTEOPTIMIZATION) {
+		NL_SET_ERR_MSG(extack, "XFRM mode must be XFRM_MODE_ROUTEOPTIMIZATION");
+		return -EINVAL;
+	}
+
+	x->props.header_len = sizeof(struct ipv6_destopt_hdr) +
+		calc_padlen(sizeof(struct ipv6_destopt_hdr), 6) +
+		sizeof(struct ipv6_destopt_hao);
+	WARN_ON(x->props.header_len != 24);
+
+	return 0;
+}
+
+/*
+ * Do nothing about destroying since it has no specific operation for
+ * destination options header unlike IPsec protocols.
+ */
+static void mip6_destopt_destroy(struct xfrm_state *x)
+{
+}
+
+static const struct xfrm_type mip6_destopt_type = {
+	.owner		= THIS_MODULE,
+	.proto		= IPPROTO_DSTOPTS,
+	.flags		= XFRM_TYPE_NON_FRAGMENT | XFRM_TYPE_LOCAL_COADDR,
+	.init_state	= mip6_destopt_init_state,
+	.destructor	= mip6_destopt_destroy,
+	.input		= mip6_destopt_input,
+	.output		= mip6_destopt_output,
+	.reject		= mip6_destopt_reject,
+};
+
+static int mip6_rthdr_input(struct xfrm_state *x, struct sk_buff *skb)
+{
+	const struct ipv6hdr *iph = ipv6_hdr(skb);
+	struct rt2_hdr *rt2 = (struct rt2_hdr *)skb->data;
+	int err = rt2->rt_hdr.nexthdr;
+
+	spin_lock(&x->lock);
+	if (!ipv6_addr_equal(&iph->daddr, (struct in6_addr *)x->coaddr) &&
+	    !ipv6_addr_any((struct in6_addr *)x->coaddr))
+		err = -ENOENT;
+	spin_unlock(&x->lock);
+
+	return err;
+}
+
+/* Routing Header type 2 is inserted.
+ * IP Header's dst address is replaced with Routing Header's Home Address.
+ */
+static int mip6_rthdr_output(struct xfrm_state *x, struct sk_buff *skb)
+{
+	struct ipv6hdr *iph;
+	struct rt2_hdr *rt2;
+	u8 nexthdr;
+
+	skb_push(skb, -skb_network_offset(skb));
+	iph = ipv6_hdr(skb);
+
+	nexthdr = *skb_mac_header(skb);
+	*skb_mac_header(skb) = IPPROTO_ROUTING;
+
+	rt2 = (struct rt2_hdr *)skb_transport_header(skb);
+	rt2->rt_hdr.nexthdr = nexthdr;
+	rt2->rt_hdr.hdrlen = (x->props.header_len >> 3) - 1;
+	rt2->rt_hdr.type = IPV6_SRCRT_TYPE_2;
+	rt2->rt_hdr.segments_left = 1;
+	memset(&rt2->reserved, 0, sizeof(rt2->reserved));
+
+	WARN_ON(rt2->rt_hdr.hdrlen != 2);
+
+	memcpy(&rt2->addr, &iph->daddr, sizeof(rt2->addr));
+	spin_lock_bh(&x->lock);
+	memcpy(&iph->daddr, x->coaddr, sizeof(iph->daddr));
+	spin_unlock_bh(&x->lock);
+
+	return 0;
+}
+
+static int mip6_rthdr_init_state(struct xfrm_state *x, struct netlink_ext_ack *extack)
+{
+	if (x->id.spi) {
+		NL_SET_ERR_MSG(extack, "SPI must be 0");
+		return -EINVAL;
+	}
+	if (x->props.mode != XFRM_MODE_ROUTEOPTIMIZATION) {
+		NL_SET_ERR_MSG(extack, "XFRM mode must be XFRM_MODE_ROUTEOPTIMIZATION");
+		return -EINVAL;
+	}
+
+	x->props.header_len = sizeof(struct rt2_hdr);
+
+	return 0;
+}
+
+/*
+ * Do nothing about destroying since it has no specific operation for routing
+ * header type 2 unlike IPsec protocols.
+ */
+static void mip6_rthdr_destroy(struct xfrm_state *x)
+{
+}
+
+static const struct xfrm_type mip6_rthdr_type = {
+	.owner		= THIS_MODULE,
+	.proto		= IPPROTO_ROUTING,
+	.flags		= XFRM_TYPE_NON_FRAGMENT | XFRM_TYPE_REMOTE_COADDR,
+	.init_state	= mip6_rthdr_init_state,
+	.destructor	= mip6_rthdr_destroy,
+	.input		= mip6_rthdr_input,
+	.output		= mip6_rthdr_output,
+};
+
+static int __init mip6_init(void)
+{
+	pr_info("Mobile IPv6\n");
+
+	if (xfrm_register_type(&mip6_destopt_type, AF_INET6) < 0) {
+		pr_info("%s: can't add xfrm type(destopt)\n", __func__);
+		goto mip6_destopt_xfrm_fail;
+	}
+	if (xfrm_register_type(&mip6_rthdr_type, AF_INET6) < 0) {
+		pr_info("%s: can't add xfrm type(rthdr)\n", __func__);
+		goto mip6_rthdr_xfrm_fail;
+	}
+	if (rawv6_mh_filter_register(mip6_mh_filter) < 0) {
+		pr_info("%s: can't add rawv6 mh filter\n", __func__);
+		goto mip6_rawv6_mh_fail;
+	}
+
+
+	return 0;
+
+ mip6_rawv6_mh_fail:
+	xfrm_unregister_type(&mip6_rthdr_type, AF_INET6);
+ mip6_rthdr_xfrm_fail:
+	xfrm_unregister_type(&mip6_destopt_type, AF_INET6);
+ mip6_destopt_xfrm_fail:
+	return -EAGAIN;
+}
+
+static void __exit mip6_fini(void)
+{
+	if (rawv6_mh_filter_unregister(mip6_mh_filter) < 0)
+		pr_info("%s: can't remove rawv6 mh filter\n", __func__);
+	xfrm_unregister_type(&mip6_rthdr_type, AF_INET6);
+	xfrm_unregister_type(&mip6_destopt_type, AF_INET6);
+}
+
+module_init(mip6_init);
+module_exit(mip6_fini);
+
+MODULE_LICENSE("GPL");
+MODULE_ALIAS_XFRM_TYPE(AF_INET6, XFRM_PROTO_DSTOPTS);
+MODULE_ALIAS_XFRM_TYPE(AF_INET6, XFRM_PROTO_ROUTING);