patch-2.3.99-pre2 linux/net/ipv4/netfilter/ipt_REJECT.c
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- Lines: 146
- Date:
Fri Mar 17 10:56:20 2000
- Orig file:
v2.3.99-pre1/linux/net/ipv4/netfilter/ipt_REJECT.c
- Orig date:
Wed Dec 31 16:00:00 1969
diff -u --recursive --new-file v2.3.99-pre1/linux/net/ipv4/netfilter/ipt_REJECT.c linux/net/ipv4/netfilter/ipt_REJECT.c
@@ -0,0 +1,145 @@
+/*
+ * This is a module which is used for rejecting packets.
+ * Added support for customized reject packets (Jozsef Kadlecsik).
+ */
+#include <linux/module.h>
+#include <linux/skbuff.h>
+#include <linux/ip.h>
+#include <net/icmp.h>
+#include <net/tcp.h>
+struct in_device;
+#include <net/route.h>
+#include <linux/netfilter_ipv4/ip_tables.h>
+#include <linux/netfilter_ipv4/ipt_REJECT.h>
+EXPORT_NO_SYMBOLS;
+
+#if 0
+#define DEBUGP printk
+#else
+#define DEBUGP(format, args...)
+#endif
+
+static unsigned int reject(struct sk_buff **pskb,
+ unsigned int hooknum,
+ const struct net_device *in,
+ const struct net_device *out,
+ const void *targinfo,
+ void *userinfo)
+{
+ const struct ipt_reject_info *reject = targinfo;
+
+ switch (reject->with) {
+ case IPT_ICMP_NET_UNREACHABLE:
+ icmp_send(*pskb, ICMP_DEST_UNREACH, ICMP_NET_UNREACH, 0);
+ break;
+ case IPT_ICMP_HOST_UNREACHABLE:
+ icmp_send(*pskb, ICMP_DEST_UNREACH, ICMP_HOST_UNREACH, 0);
+ break;
+ case IPT_ICMP_PROT_UNREACHABLE:
+ icmp_send(*pskb, ICMP_DEST_UNREACH, ICMP_PROT_UNREACH, 0);
+ break;
+ case IPT_ICMP_PORT_UNREACHABLE:
+ icmp_send(*pskb, ICMP_DEST_UNREACH, ICMP_PORT_UNREACH, 0);
+ break;
+ case IPT_ICMP_ECHOREPLY: {
+ struct icmphdr *icmph = (struct icmphdr *)
+ ((u_int32_t *)(*pskb)->nh.iph + (*pskb)->nh.iph->ihl);
+ unsigned int datalen = (*pskb)->len - (*pskb)->nh.iph->ihl * 4;
+
+ /* Not non-head frags, or truncated */
+ if (((ntohs((*pskb)->nh.iph->frag_off) & IP_OFFSET) == 0)
+ && datalen >= 4) {
+ /* Usually I don't like cut & pasting code,
+ but dammit, my party is starting in 45
+ mins! --RR */
+ struct icmp_bxm icmp_param;
+
+ icmp_param.icmph=*icmph;
+ icmp_param.icmph.type=ICMP_ECHOREPLY;
+ icmp_param.data_ptr=(icmph+1);
+ icmp_param.data_len=datalen;
+ icmp_reply(&icmp_param, *pskb);
+ }
+ }
+ break;
+ case IPT_TCP_RESET:
+ tcp_v4_send_reset(*pskb);
+ break;
+ }
+
+ return NF_DROP;
+}
+
+static inline int find_ping_match(const struct ipt_entry_match *m)
+{
+ const struct ipt_icmp *icmpinfo = (const struct ipt_icmp *)m->data;
+
+ if (strcmp(m->u.match->name, "icmp") == 0
+ && icmpinfo->type == ICMP_ECHO
+ && !(icmpinfo->invflags & IPT_ICMP_INV))
+ return 1;
+
+ return 0;
+}
+
+static int check(const char *tablename,
+ const struct ipt_entry *e,
+ void *targinfo,
+ unsigned int targinfosize,
+ unsigned int hook_mask)
+{
+ const struct ipt_reject_info *rejinfo = targinfo;
+
+ if (targinfosize != IPT_ALIGN(sizeof(struct ipt_icmp))) {
+ DEBUGP("REJECT: targinfosize %u != 0\n", targinfosize);
+ return 0;
+ }
+
+ /* Only allow these for packet filtering. */
+ if ((hook_mask & ~((1 << NF_IP_LOCAL_IN)
+ | (1 << NF_IP_FORWARD)
+ | (1 << NF_IP_LOCAL_OUT))) != 0) {
+ DEBUGP("REJECT: bad hook mask %X\n", hook_mask);
+ return 0;
+ }
+
+ if (rejinfo->with == IPT_ICMP_ECHOREPLY) {
+ /* Must specify that it's an ICMP ping packet. */
+ if (e->ip.proto != IPPROTO_ICMP
+ || (e->ip.invflags & IPT_INV_PROTO)) {
+ DEBUGP("REJECT: ECHOREPLY illegal for non-icmp\n");
+ return 0;
+ }
+ /* Must contain ICMP match. */
+ if (IPT_MATCH_ITERATE(e, find_ping_match) == 0) {
+ DEBUGP("REJECT: ECHOREPLY illegal for non-ping\n");
+ return 0;
+ }
+ } else if (rejinfo->with == IPT_TCP_RESET) {
+ if (e->ip.proto != IPPROTO_TCP
+ || (e->ip.invflags & IPT_INV_PROTO)) {
+ DEBUGP("REJECT: TCP_RESET illegal for non-tcp\n");
+ return 0;
+ }
+ }
+
+ return 1;
+}
+
+static struct ipt_target ipt_reject_reg
+= { { NULL, NULL }, "REJECT", reject, check, THIS_MODULE };
+
+static int __init init(void)
+{
+ if (ipt_register_target(&ipt_reject_reg))
+ return -EINVAL;
+ return 0;
+}
+
+static void __exit fini(void)
+{
+ ipt_unregister_target(&ipt_reject_reg);
+}
+
+module_init(init);
+module_exit(fini);
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