[NETFILTER]: Add IPv6 REJECT target
Originally written by Yasuyuki Kozakai <yasuyuki.kozakai@toshiba.co.jp>, taken from netfilter patch-o-matic and fixed up to work with current kernels. Signed-off-by: Patrick McHardy <kaber@trash.net> Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Patrick McHardy
David S. Miller
parent
7567662ba8
commit
764d8a9f24
4 changed files with 313 additions and 0 deletions
18
include/linux/netfilter_ipv6/ip6t_REJECT.h
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18
include/linux/netfilter_ipv6/ip6t_REJECT.h
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@ -0,0 +1,18 @@
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#ifndef _IP6T_REJECT_H
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#define _IP6T_REJECT_H
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enum ip6t_reject_with {
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IP6T_ICMP6_NO_ROUTE,
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IP6T_ICMP6_ADM_PROHIBITED,
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IP6T_ICMP6_NOT_NEIGHBOUR,
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IP6T_ICMP6_ADDR_UNREACH,
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IP6T_ICMP6_PORT_UNREACH,
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IP6T_ICMP6_ECHOREPLY,
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IP6T_TCP_RESET
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};
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struct ip6t_reject_info {
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u_int32_t with; /* reject type */
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};
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#endif /*_IP6T_REJECT_H*/
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@ -199,6 +199,16 @@ config IP6_NF_TARGET_LOG
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To compile it as a module, choose M here. If unsure, say N.
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config IP6_NF_TARGET_REJECT
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tristate "REJECT target support"
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depends on IP6_NF_FILTER
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help
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The REJECT target allows a filtering rule to specify that an ICMPv6
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error should be issued in response to an incoming packet, rather
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than silently being dropped.
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To compile it as a module, choose M here. If unsure, say N.
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# if [ "$CONFIG_IP6_NF_FILTER" != "n" ]; then
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# dep_tristate ' REJECT target support' CONFIG_IP6_NF_TARGET_REJECT $CONFIG_IP6_NF_FILTER
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# if [ "$CONFIG_EXPERIMENTAL" = "y" ]; then
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@ -24,4 +24,5 @@ obj-$(CONFIG_IP6_NF_QUEUE) += ip6_queue.o
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obj-$(CONFIG_IP6_NF_TARGET_LOG) += ip6t_LOG.o
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obj-$(CONFIG_IP6_NF_RAW) += ip6table_raw.o
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obj-$(CONFIG_IP6_NF_MATCH_HL) += ip6t_hl.o
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obj-$(CONFIG_IP6_NF_TARGET_REJECT) += ip6t_REJECT.o
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obj-$(CONFIG_NETFILTER_NETLINK_QUEUE) += ip6t_NFQUEUE.o
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284
net/ipv6/netfilter/ip6t_REJECT.c
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284
net/ipv6/netfilter/ip6t_REJECT.c
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@ -0,0 +1,284 @@
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/*
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* IP6 tables REJECT target module
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* Linux INET6 implementation
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*
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* Copyright (C)2003 USAGI/WIDE Project
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*
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* Authors:
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* Yasuyuki Kozakai <yasuyuki.kozakai@toshiba.co.jp>
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*
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* Based on net/ipv4/netfilter/ipt_REJECT.c
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*/
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#include <linux/config.h>
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#include <linux/module.h>
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#include <linux/skbuff.h>
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#include <linux/icmpv6.h>
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#include <linux/netdevice.h>
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#include <net/ipv6.h>
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#include <net/tcp.h>
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#include <net/icmp.h>
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#include <net/ip6_checksum.h>
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#include <net/ip6_fib.h>
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#include <net/ip6_route.h>
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#include <net/flow.h>
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#include <linux/netfilter_ipv6/ip6_tables.h>
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#include <linux/netfilter_ipv6/ip6t_REJECT.h>
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MODULE_AUTHOR("Yasuyuki KOZAKAI <yasuyuki.kozakai@toshiba.co.jp>");
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MODULE_DESCRIPTION("IP6 tables REJECT target module");
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MODULE_LICENSE("GPL");
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#if 0
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#define DEBUGP printk
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#else
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#define DEBUGP(format, args...)
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#endif
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/* Send RST reply */
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static void send_reset(struct sk_buff *oldskb)
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{
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struct sk_buff *nskb;
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struct tcphdr otcph, *tcph;
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unsigned int otcplen, hh_len;
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int tcphoff, needs_ack;
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struct ipv6hdr *oip6h = oldskb->nh.ipv6h, *ip6h;
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struct dst_entry *dst = NULL;
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u8 proto;
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struct flowi fl;
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if ((!(ipv6_addr_type(&oip6h->saddr) & IPV6_ADDR_UNICAST)) ||
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(!(ipv6_addr_type(&oip6h->daddr) & IPV6_ADDR_UNICAST))) {
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DEBUGP("ip6t_REJECT: addr is not unicast.\n");
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return;
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}
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proto = oip6h->nexthdr;
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tcphoff = ipv6_skip_exthdr(oldskb, ((u8*)(oip6h+1) - oldskb->data), &proto);
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if ((tcphoff < 0) || (tcphoff > oldskb->len)) {
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DEBUGP("ip6t_REJECT: Can't get TCP header.\n");
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return;
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}
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otcplen = oldskb->len - tcphoff;
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/* IP header checks: fragment, too short. */
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if ((proto != IPPROTO_TCP) || (otcplen < sizeof(struct tcphdr))) {
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DEBUGP("ip6t_REJECT: proto(%d) != IPPROTO_TCP, or too short. otcplen = %d\n",
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proto, otcplen);
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return;
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}
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if (skb_copy_bits(oldskb, tcphoff, &otcph, sizeof(struct tcphdr)))
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BUG();
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/* No RST for RST. */
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if (otcph.rst) {
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DEBUGP("ip6t_REJECT: RST is set\n");
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return;
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}
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/* Check checksum. */
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if (csum_ipv6_magic(&oip6h->saddr, &oip6h->daddr, otcplen, IPPROTO_TCP,
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skb_checksum(oldskb, tcphoff, otcplen, 0))) {
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DEBUGP("ip6t_REJECT: TCP checksum is invalid\n");
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return;
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}
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memset(&fl, 0, sizeof(fl));
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fl.proto = IPPROTO_TCP;
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ipv6_addr_copy(&fl.fl6_src, &oip6h->daddr);
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ipv6_addr_copy(&fl.fl6_dst, &oip6h->saddr);
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fl.fl_ip_sport = otcph.dest;
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fl.fl_ip_dport = otcph.source;
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dst = ip6_route_output(NULL, &fl);
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if (dst == NULL)
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return;
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if (dst->error ||
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xfrm_lookup(&dst, &fl, NULL, 0)) {
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dst_release(dst);
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return;
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}
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hh_len = (dst->dev->hard_header_len + 15)&~15;
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nskb = alloc_skb(hh_len + 15 + dst->header_len + sizeof(struct ipv6hdr)
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+ sizeof(struct tcphdr) + dst->trailer_len,
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GFP_ATOMIC);
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if (!nskb) {
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if (net_ratelimit())
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printk("ip6t_REJECT: Can't alloc skb\n");
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dst_release(dst);
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return;
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}
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nskb->dst = dst;
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skb_reserve(nskb, hh_len + dst->header_len);
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ip6h = nskb->nh.ipv6h = (struct ipv6hdr *)
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skb_put(nskb, sizeof(struct ipv6hdr));
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ip6h->version = 6;
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ip6h->hop_limit = dst_metric(dst, RTAX_HOPLIMIT);
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ip6h->nexthdr = IPPROTO_TCP;
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ip6h->payload_len = htons(sizeof(struct tcphdr));
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ipv6_addr_copy(&ip6h->saddr, &oip6h->daddr);
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ipv6_addr_copy(&ip6h->daddr, &oip6h->saddr);
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tcph = (struct tcphdr *)skb_put(nskb, sizeof(struct tcphdr));
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/* Truncate to length (no data) */
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tcph->doff = sizeof(struct tcphdr)/4;
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tcph->source = otcph.dest;
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tcph->dest = otcph.source;
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if (otcph.ack) {
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needs_ack = 0;
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tcph->seq = otcph.ack_seq;
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tcph->ack_seq = 0;
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} else {
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needs_ack = 1;
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tcph->ack_seq = htonl(ntohl(otcph.seq) + otcph.syn + otcph.fin
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+ otcplen - (otcph.doff<<2));
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tcph->seq = 0;
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}
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/* Reset flags */
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((u_int8_t *)tcph)[13] = 0;
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tcph->rst = 1;
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tcph->ack = needs_ack;
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tcph->window = 0;
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tcph->urg_ptr = 0;
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tcph->check = 0;
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/* Adjust TCP checksum */
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tcph->check = csum_ipv6_magic(&nskb->nh.ipv6h->saddr,
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&nskb->nh.ipv6h->daddr,
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sizeof(struct tcphdr), IPPROTO_TCP,
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csum_partial((char *)tcph,
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sizeof(struct tcphdr), 0));
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NF_HOOK(PF_INET6, NF_IP6_LOCAL_OUT, nskb, NULL, nskb->dst->dev,
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dst_output);
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}
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static inline void
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send_unreach(struct sk_buff *skb_in, unsigned char code, unsigned int hooknum)
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{
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if (hooknum == NF_IP6_LOCAL_OUT && skb_in->dev == NULL)
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skb_in->dev = &loopback_dev;
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icmpv6_send(skb_in, ICMPV6_DEST_UNREACH, code, 0, NULL);
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}
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static unsigned int reject6_target(struct sk_buff **pskb,
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const struct net_device *in,
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const struct net_device *out,
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unsigned int hooknum,
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const void *targinfo,
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void *userinfo)
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{
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const struct ip6t_reject_info *reject = targinfo;
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DEBUGP(KERN_DEBUG "%s: medium point\n", __FUNCTION__);
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/* WARNING: This code causes reentry within ip6tables.
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This means that the ip6tables jump stack is now crap. We
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must return an absolute verdict. --RR */
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switch (reject->with) {
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case IP6T_ICMP6_NO_ROUTE:
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send_unreach(*pskb, ICMPV6_NOROUTE, hooknum);
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break;
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case IP6T_ICMP6_ADM_PROHIBITED:
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send_unreach(*pskb, ICMPV6_ADM_PROHIBITED, hooknum);
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break;
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case IP6T_ICMP6_NOT_NEIGHBOUR:
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send_unreach(*pskb, ICMPV6_NOT_NEIGHBOUR, hooknum);
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break;
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case IP6T_ICMP6_ADDR_UNREACH:
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send_unreach(*pskb, ICMPV6_ADDR_UNREACH, hooknum);
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break;
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case IP6T_ICMP6_PORT_UNREACH:
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send_unreach(*pskb, ICMPV6_PORT_UNREACH, hooknum);
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break;
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case IP6T_ICMP6_ECHOREPLY:
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/* Do nothing */
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break;
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case IP6T_TCP_RESET:
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send_reset(*pskb);
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break;
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default:
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if (net_ratelimit())
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printk(KERN_WARNING "ip6t_REJECT: case %u not handled yet\n", reject->with);
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break;
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}
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return NF_DROP;
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}
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static int check(const char *tablename,
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const struct ip6t_entry *e,
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void *targinfo,
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unsigned int targinfosize,
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unsigned int hook_mask)
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{
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const struct ip6t_reject_info *rejinfo = targinfo;
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if (targinfosize != IP6T_ALIGN(sizeof(struct ip6t_reject_info))) {
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DEBUGP("ip6t_REJECT: targinfosize %u != 0\n", targinfosize);
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return 0;
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}
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/* Only allow these for packet filtering. */
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if (strcmp(tablename, "filter") != 0) {
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DEBUGP("ip6t_REJECT: bad table `%s'.\n", tablename);
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return 0;
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}
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if ((hook_mask & ~((1 << NF_IP6_LOCAL_IN)
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| (1 << NF_IP6_FORWARD)
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| (1 << NF_IP6_LOCAL_OUT))) != 0) {
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DEBUGP("ip6t_REJECT: bad hook mask %X\n", hook_mask);
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return 0;
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}
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if (rejinfo->with == IP6T_ICMP6_ECHOREPLY) {
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printk("ip6t_REJECT: ECHOREPLY is not supported.\n");
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return 0;
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} else if (rejinfo->with == IP6T_TCP_RESET) {
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/* Must specify that it's a TCP packet */
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if (e->ipv6.proto != IPPROTO_TCP
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|| (e->ipv6.invflags & IP6T_INV_PROTO)) {
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DEBUGP("ip6t_REJECT: TCP_RESET illegal for non-tcp\n");
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return 0;
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}
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}
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return 1;
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}
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static struct ip6t_target ip6t_reject_reg = {
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.name = "REJECT",
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.target = reject6_target,
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.checkentry = check,
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.me = THIS_MODULE
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};
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static int __init init(void)
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{
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if (ip6t_register_target(&ip6t_reject_reg))
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return -EINVAL;
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return 0;
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}
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static void __exit fini(void)
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{
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ip6t_unregister_target(&ip6t_reject_reg);
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}
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module_init(init);
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module_exit(fini);
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