1 files changed, 271 insertions, 0 deletions
diff --git a/net/ipv6/netfilter/ip6t_REJECT.c b/net/ipv6/netfilter/ip6t_REJECT.c
new file mode 100644
index 00000000..09d30498
--- /dev/null
+++ b/net/ipv6/netfilter/ip6t_REJECT.c
@@ -0,0 +1,271 @@
+/*
+ * IP6 tables REJECT target module
+ * Linux INET6 implementation
+ *
+ * Copyright (C)2003 USAGI/WIDE Project
+ *
+ * Authors:
+ *	Yasuyuki Kozakai	<yasuyuki.kozakai@toshiba.co.jp>
+ *
+ * Based on net/ipv4/netfilter/ipt_REJECT.c
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/gfp.h>
+#include <linux/module.h>
+#include <linux/skbuff.h>
+#include <linux/icmpv6.h>
+#include <linux/netdevice.h>
+#include <net/ipv6.h>
+#include <net/tcp.h>
+#include <net/icmp.h>
+#include <net/ip6_checksum.h>
+#include <net/ip6_fib.h>
+#include <net/ip6_route.h>
+#include <net/flow.h>
+#include <linux/netfilter/x_tables.h>
+#include <linux/netfilter_ipv6/ip6_tables.h>
+#include <linux/netfilter_ipv6/ip6t_REJECT.h>
+
+MODULE_AUTHOR("Yasuyuki KOZAKAI <yasuyuki.kozakai@toshiba.co.jp>");
+MODULE_DESCRIPTION("Xtables: packet \"rejection\" target for IPv6");
+MODULE_LICENSE("GPL");
+
+/* Send RST reply */
+static void send_reset(struct net *net, struct sk_buff *oldskb)
+{
+	struct sk_buff *nskb;
+	struct tcphdr otcph, *tcph;
+	unsigned int otcplen, hh_len;
+	int tcphoff, needs_ack;
+	const struct ipv6hdr *oip6h = ipv6_hdr(oldskb);
+	struct ipv6hdr *ip6h;
+#define DEFAULT_TOS_VALUE	0x0U
+	const __u8 tclass = DEFAULT_TOS_VALUE;
+	struct dst_entry *dst = NULL;
+	u8 proto;
+	struct flowi6 fl6;
+
+	if ((!(ipv6_addr_type(&oip6h->saddr) & IPV6_ADDR_UNICAST)) ||
+	    (!(ipv6_addr_type(&oip6h->daddr) & IPV6_ADDR_UNICAST))) {
+		pr_debug("addr is not unicast.\n");
+		return;
+	}
+
+	proto = oip6h->nexthdr;
+	tcphoff = ipv6_skip_exthdr(oldskb, ((u8*)(oip6h+1) - oldskb->data), &proto);
+
+	if ((tcphoff < 0) || (tcphoff > oldskb->len)) {
+		pr_debug("Cannot get TCP header.\n");
+		return;
+	}
+
+	otcplen = oldskb->len - tcphoff;
+
+	/* IP header checks: fragment, too short. */
+	if (proto != IPPROTO_TCP || otcplen < sizeof(struct tcphdr)) {
+		pr_debug("proto(%d) != IPPROTO_TCP, "
+			 "or too short. otcplen = %d\n",
+			 proto, otcplen);
+		return;
+	}
+
+	if (skb_copy_bits(oldskb, tcphoff, &otcph, sizeof(struct tcphdr)))
+		BUG();
+
+	/* No RST for RST. */
+	if (otcph.rst) {
+		pr_debug("RST is set\n");
+		return;
+	}
+
+	/* Check checksum. */
+	if (csum_ipv6_magic(&oip6h->saddr, &oip6h->daddr, otcplen, IPPROTO_TCP,
+			    skb_checksum(oldskb, tcphoff, otcplen, 0))) {
+		pr_debug("TCP checksum is invalid\n");
+		return;
+	}
+
+	memset(&fl6, 0, sizeof(fl6));
+	fl6.flowi6_proto = IPPROTO_TCP;
+	ipv6_addr_copy(&fl6.saddr, &oip6h->daddr);
+	ipv6_addr_copy(&fl6.daddr, &oip6h->saddr);
+	fl6.fl6_sport = otcph.dest;
+	fl6.fl6_dport = otcph.source;
+	security_skb_classify_flow(oldskb, flowi6_to_flowi(&fl6));
+	dst = ip6_route_output(net, NULL, &fl6);
+	if (dst == NULL || dst->error) {
+		dst_release(dst);
+		return;
+	}
+	dst = xfrm_lookup(net, dst, flowi6_to_flowi(&fl6), NULL, 0);
+	if (IS_ERR(dst))
+		return;
+
+	hh_len = (dst->dev->hard_header_len + 15)&~15;
+	nskb = alloc_skb(hh_len + 15 + dst->header_len + sizeof(struct ipv6hdr)
+			 + sizeof(struct tcphdr) + dst->trailer_len,
+			 GFP_ATOMIC);
+
+	if (!nskb) {
+		if (net_ratelimit())
+			pr_debug("cannot alloc skb\n");
+		dst_release(dst);
+		return;
+	}
+
+	skb_dst_set(nskb, dst);
+
+	skb_reserve(nskb, hh_len + dst->header_len);
+
+	skb_put(nskb, sizeof(struct ipv6hdr));
+	skb_reset_network_header(nskb);
+	ip6h = ipv6_hdr(nskb);
+	*(__be32 *)ip6h =  htonl(0x60000000 | (tclass << 20));
+	ip6h->hop_limit = ip6_dst_hoplimit(dst);
+	ip6h->nexthdr = IPPROTO_TCP;
+	ipv6_addr_copy(&ip6h->saddr, &oip6h->daddr);
+	ipv6_addr_copy(&ip6h->daddr, &oip6h->saddr);
+
+	tcph = (struct tcphdr *)skb_put(nskb, sizeof(struct tcphdr));
+	/* Truncate to length (no data) */
+	tcph->doff = sizeof(struct tcphdr)/4;
+	tcph->source = otcph.dest;
+	tcph->dest = otcph.source;
+
+	if (otcph.ack) {
+		needs_ack = 0;
+		tcph->seq = otcph.ack_seq;
+		tcph->ack_seq = 0;
+	} else {
+		needs_ack = 1;
+		tcph->ack_seq = htonl(ntohl(otcph.seq) + otcph.syn + otcph.fin
+				      + otcplen - (otcph.doff<<2));
+		tcph->seq = 0;
+	}
+
+	/* Reset flags */
+	((u_int8_t *)tcph)[13] = 0;
+	tcph->rst = 1;
+	tcph->ack = needs_ack;
+	tcph->window = 0;
+	tcph->urg_ptr = 0;
+	tcph->check = 0;
+
+	/* Adjust TCP checksum */
+	tcph->check = csum_ipv6_magic(&ipv6_hdr(nskb)->saddr,
+				      &ipv6_hdr(nskb)->daddr,
+				      sizeof(struct tcphdr), IPPROTO_TCP,
+				      csum_partial(tcph,
+						   sizeof(struct tcphdr), 0));
+
+	nf_ct_attach(nskb, oldskb);
+
+	ip6_local_out(nskb);
+}
+
+static inline void
+send_unreach(struct net *net, struct sk_buff *skb_in, unsigned char code,
+	     unsigned int hooknum)
+{
+	if (hooknum == NF_INET_LOCAL_OUT && skb_in->dev == NULL)
+		skb_in->dev = net->loopback_dev;
+
+	icmpv6_send(skb_in, ICMPV6_DEST_UNREACH, code, 0);
+#ifdef CONFIG_IP6_NF_TARGET_REJECT_SKERR
+	if (skb_in->sk) {
+		icmpv6_err_convert(ICMPV6_DEST_UNREACH, code,
+				   &skb_in->sk->sk_err);
+		skb_in->sk->sk_error_report(skb_in->sk);
+		pr_debug("ip6t_REJECT: sk_err=%d for skb=%p sk=%p\n",
+			skb_in->sk->sk_err, skb_in, skb_in->sk);
+	}
+#endif
+}
+
+static unsigned int
+reject_tg6(struct sk_buff *skb, const struct xt_action_param *par)
+{
+	const struct ip6t_reject_info *reject = par->targinfo;
+	struct net *net = dev_net((par->in != NULL) ? par->in : par->out);
+
+	pr_debug("%s: medium point\n", __func__);
+	switch (reject->with) {
+	case IP6T_ICMP6_NO_ROUTE:
+		send_unreach(net, skb, ICMPV6_NOROUTE, par->hooknum);
+		break;
+	case IP6T_ICMP6_ADM_PROHIBITED:
+		send_unreach(net, skb, ICMPV6_ADM_PROHIBITED, par->hooknum);
+		break;
+	case IP6T_ICMP6_NOT_NEIGHBOUR:
+		send_unreach(net, skb, ICMPV6_NOT_NEIGHBOUR, par->hooknum);
+		break;
+	case IP6T_ICMP6_ADDR_UNREACH:
+		send_unreach(net, skb, ICMPV6_ADDR_UNREACH, par->hooknum);
+		break;
+	case IP6T_ICMP6_PORT_UNREACH:
+		send_unreach(net, skb, ICMPV6_PORT_UNREACH, par->hooknum);
+		break;
+	case IP6T_ICMP6_ECHOREPLY:
+		/* Do nothing */
+		break;
+	case IP6T_TCP_RESET:
+		send_reset(net, skb);
+		break;
+	default:
+		if (net_ratelimit())
+			pr_info("case %u not handled yet\n", reject->with);
+		break;
+	}
+
+	return NF_DROP;
+}
+
+static int reject_tg6_check(const struct xt_tgchk_param *par)
+{
+	const struct ip6t_reject_info *rejinfo = par->targinfo;
+	const struct ip6t_entry *e = par->entryinfo;
+
+	if (rejinfo->with == IP6T_ICMP6_ECHOREPLY) {
+		pr_info("ECHOREPLY is not supported.\n");
+		return -EINVAL;
+	} else if (rejinfo->with == IP6T_TCP_RESET) {
+		/* Must specify that it's a TCP packet */
+		if (e->ipv6.proto != IPPROTO_TCP ||
+		    (e->ipv6.invflags & XT_INV_PROTO)) {
+			pr_info("TCP_RESET illegal for non-tcp\n");
+			return -EINVAL;
+		}
+	}
+	return 0;
+}
+
+static struct xt_target reject_tg6_reg __read_mostly = {
+	.name		= "REJECT",
+	.family		= NFPROTO_IPV6,
+	.target		= reject_tg6,
+	.targetsize	= sizeof(struct ip6t_reject_info),
+	.table		= "filter",
+	.hooks		= (1 << NF_INET_LOCAL_IN) | (1 << NF_INET_FORWARD) |
+			  (1 << NF_INET_LOCAL_OUT),
+	.checkentry	= reject_tg6_check,
+	.me		= THIS_MODULE
+};
+
+static int __init reject_tg6_init(void)
+{
+	return xt_register_target(&reject_tg6_reg);
+}
+
+static void __exit reject_tg6_exit(void)
+{
+	xt_unregister_target(&reject_tg6_reg);
+}
+
+module_init(reject_tg6_init);
+module_exit(reject_tg6_exit);