--- /dev/null
+/*
+ * 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.
+ */
+
+#include <linux/config.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_ipv6/ip6_tables.h>
+#include <linux/netfilter_ipv6/ip6t_REJECT.h>
+
+MODULE_AUTHOR("Yasuyuki KOZAKAI <yasuyuki.kozakai@toshiba.co.jp>");
+MODULE_DESCRIPTION("IP6 tables REJECT target module");
+MODULE_LICENSE("GPL");
+
+#if 0
+#define DEBUGP printk
+#else
+#define DEBUGP(format, args...)
+#endif
+
+/* Send RST reply */
+static void send_reset(struct sk_buff *oldskb)
+{
+ struct sk_buff *nskb;
+ struct tcphdr otcph, *tcph;
+ unsigned int otcplen, hh_len;
+ int tcphoff, needs_ack;
+ struct ipv6hdr *oip6h = oldskb->nh.ipv6h, *ip6h;
+ struct dst_entry *dst = NULL;
+ u8 proto;
+ struct flowi fl;
+
+ if ((!(ipv6_addr_type(&oip6h->saddr) & IPV6_ADDR_UNICAST)) ||
+ (!(ipv6_addr_type(&oip6h->daddr) & IPV6_ADDR_UNICAST))) {
+ DEBUGP("ip6t_REJECT: 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)) {
+ DEBUGP("ip6t_REJECT: Can't get TCP header.\n");
+ return;
+ }
+
+ otcplen = oldskb->len - tcphoff;
+
+ /* IP header checks: fragment, too short. */
+ if ((proto != IPPROTO_TCP) || (otcplen < sizeof(struct tcphdr))) {
+ DEBUGP("ip6t_REJECT: 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) {
+ DEBUGP("ip6t_REJECT: RST is set\n");
+ return;
+ }
+
+ /* Check checksum. */
+ if (csum_ipv6_magic(&oip6h->saddr, &oip6h->daddr, otcplen, IPPROTO_TCP,
+ skb_checksum(oldskb, tcphoff, otcplen, 0))) {
+ DEBUGP("ip6t_REJECT: TCP checksum is invalid\n");
+ return;
+ }
+
+ memset(&fl, 0, sizeof(fl));
+ fl.proto = IPPROTO_TCP;
+ ipv6_addr_copy(&fl.fl6_src, &oip6h->daddr);
+ ipv6_addr_copy(&fl.fl6_dst, &oip6h->saddr);
+ fl.fl_ip_sport = otcph.dest;
+ fl.fl_ip_dport = otcph.source;
+ dst = ip6_route_output(NULL, &fl);
+ if (dst == NULL)
+ return;
+ if (dst->error ||
+ xfrm_lookup(&dst, &fl, NULL, 0)) {
+ dst_release(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())
+ printk("ip6t_REJECT: Can't alloc skb\n");
+ dst_release(dst);
+ return;
+ }
+
+ nskb->dst = dst;
+
+ skb_reserve(nskb, hh_len + dst->header_len);
+
+ ip6h = nskb->nh.ipv6h = (struct ipv6hdr *)
+ skb_put(nskb, sizeof(struct ipv6hdr));
+ ip6h->version = 6;
+ ip6h->hop_limit = dst_metric(dst, RTAX_HOPLIMIT);
+ ip6h->nexthdr = IPPROTO_TCP;
+ ip6h->payload_len = htons(sizeof(struct tcphdr));
+ 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(&nskb->nh.ipv6h->saddr,
+ &nskb->nh.ipv6h->daddr,
+ sizeof(struct tcphdr), IPPROTO_TCP,
+ csum_partial((char *)tcph,
+ sizeof(struct tcphdr), 0));
+
+ NF_HOOK(PF_INET6, NF_IP6_LOCAL_OUT, nskb, NULL, nskb->dst->dev,
+ dst_output);
+}
+
+static inline void
+send_unreach(struct sk_buff *skb_in, unsigned char code, unsigned int hooknum)
+{
+ if (hooknum == NF_IP6_LOCAL_OUT && skb_in->dev == NULL)
+ skb_in->dev = &loopback_dev;
+
+ icmpv6_send(skb_in, ICMPV6_DEST_UNREACH, code, 0, NULL);
+}
+
+static unsigned int reject6_target(struct sk_buff **pskb,
+ const struct net_device *in,
+ const struct net_device *out,
+ unsigned int hooknum,
+ const void *targinfo,
+ void *userinfo)
+{
+ const struct ip6t_reject_info *reject = targinfo;
+
+ DEBUGP(KERN_DEBUG "%s: medium point\n", __FUNCTION__);
+ /* WARNING: This code causes reentry within ip6tables.
+ This means that the ip6tables jump stack is now crap. We
+ must return an absolute verdict. --RR */
+ switch (reject->with) {
+ case IP6T_ICMP6_NO_ROUTE:
+ send_unreach(*pskb, ICMPV6_NOROUTE, hooknum);
+ break;
+ case IP6T_ICMP6_ADM_PROHIBITED:
+ send_unreach(*pskb, ICMPV6_ADM_PROHIBITED, hooknum);
+ break;
+ case IP6T_ICMP6_NOT_NEIGHBOUR:
+ send_unreach(*pskb, ICMPV6_NOT_NEIGHBOUR, hooknum);
+ break;
+ case IP6T_ICMP6_ADDR_UNREACH:
+ send_unreach(*pskb, ICMPV6_ADDR_UNREACH, hooknum);
+ break;
+ case IP6T_ICMP6_PORT_UNREACH:
+ send_unreach(*pskb, ICMPV6_PORT_UNREACH, hooknum);
+ break;
+ case IP6T_ICMP6_ECHOREPLY:
+ /* Do nothing */
+ break;
+ case IP6T_TCP_RESET:
+ send_reset(*pskb);
+ break;
+ default:
+ if (net_ratelimit())
+ printk(KERN_WARNING "ip6t_REJECT: case %u not handled yet\n", reject->with);
+ break;
+ }
+
+ return NF_DROP;
+}
+
+static int check(const char *tablename,
+ const struct ip6t_entry *e,
+ void *targinfo,
+ unsigned int targinfosize,
+ unsigned int hook_mask)
+{
+ const struct ip6t_reject_info *rejinfo = targinfo;
+
+ if (targinfosize != IP6T_ALIGN(sizeof(struct ip6t_reject_info))) {
+ DEBUGP("ip6t_REJECT: targinfosize %u != 0\n", targinfosize);
+ return 0;
+ }
+
+ /* Only allow these for packet filtering. */
+ if (strcmp(tablename, "filter") != 0) {
+ DEBUGP("ip6t_REJECT: bad table `%s'.\n", tablename);
+ return 0;
+ }
+
+ if ((hook_mask & ~((1 << NF_IP6_LOCAL_IN)
+ | (1 << NF_IP6_FORWARD)
+ | (1 << NF_IP6_LOCAL_OUT))) != 0) {
+ DEBUGP("ip6t_REJECT: bad hook mask %X\n", hook_mask);
+ return 0;
+ }
+
+ if (rejinfo->with == IP6T_ICMP6_ECHOREPLY) {
+ printk("ip6t_REJECT: ECHOREPLY is not supported.\n");
+ return 0;
+ } else if (rejinfo->with == IP6T_TCP_RESET) {
+ /* Must specify that it's a TCP packet */
+ if (e->ipv6.proto != IPPROTO_TCP
+ || (e->ipv6.invflags & IP6T_INV_PROTO)) {
+ DEBUGP("ip6t_REJECT: TCP_RESET illegal for non-tcp\n");
+ return 0;
+ }
+ }
+
+ return 1;
+}
+
+static struct ip6t_target ip6t_reject_reg = {
+ .name = "REJECT",
+ .target = reject6_target,
+ .checkentry = check,
+ .me = THIS_MODULE
+};
+
+static int __init init(void)
+{
+ if (ip6t_register_target(&ip6t_reject_reg))
+ return -EINVAL;
+ return 0;
+}
+
+static void __exit fini(void)
+{
+ ip6t_unregister_target(&ip6t_reject_reg);
+}
+
+module_init(init);
+module_exit(fini);
git.samba.org / sfrench / cifs-2.6.git / commitdiff