patch-2.3.99-pre2 linux/net/ipv4/netfilter/ipt_REJECT.c

• 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);