patch-2.4.21 linux-2.4.21/net/ipv4/netfilter/ip_nat_amanda.c

• Lines: 227
• Date: 2003-06-13 07:51:39.000000000 -0700
• Orig file: linux-2.4.20/net/ipv4/netfilter/ip_nat_amanda.c
• Orig date: 1969-12-31 16:00:00.000000000 -0800

diff -urN linux-2.4.20/net/ipv4/netfilter/ip_nat_amanda.c linux-2.4.21/net/ipv4/netfilter/ip_nat_amanda.c
@@ -0,0 +1,226 @@
+/* Amanda extension for TCP NAT alteration.
+ * (C) 2002 by Brian J. Murrell <netfilter@interlinx.bc.ca>
+ * based on a copy of HW's ip_nat_irc.c as well as other modules
+ *
+ *      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.
+ *
+ *	Module load syntax:
+ * 	insmod ip_nat_amanda.o
+ */
+
+#include <linux/module.h>
+#include <linux/netfilter_ipv4.h>
+#include <linux/ip.h>
+#include <linux/udp.h>
+#include <linux/kernel.h>
+#include <net/tcp.h>
+#include <net/udp.h>
+
+#include <linux/netfilter_ipv4/ip_nat.h>
+#include <linux/netfilter_ipv4/ip_nat_helper.h>
+#include <linux/netfilter_ipv4/ip_nat_rule.h>
+#include <linux/netfilter_ipv4/ip_conntrack_helper.h>
+#include <linux/netfilter_ipv4/ip_conntrack_amanda.h>
+
+
+#if 0
+#define DEBUGP printk
+#define DUMP_OFFSET(x)	printk("offset_before=%d, offset_after=%d, correction_pos=%u\n", x->offset_before, x->offset_after, x->correction_pos);
+#else
+#define DEBUGP(format, args...)
+#define DUMP_OFFSET(x)
+#endif
+
+MODULE_AUTHOR("Brian J. Murrell <netfilter@interlinx.bc.ca>");
+MODULE_DESCRIPTION("Amanda network address translation module");
+MODULE_LICENSE("GPL");
+
+/* protects amanda part of conntracks */
+DECLARE_LOCK_EXTERN(ip_amanda_lock);
+
+static unsigned int
+amanda_nat_expected(struct sk_buff **pskb,
+		 unsigned int hooknum,
+		 struct ip_conntrack *ct,
+		 struct ip_nat_info *info)
+{
+	struct ip_nat_multi_range mr;
+	u_int32_t newdstip, newsrcip, newip;
+	u_int16_t port;
+	struct ip_ct_amanda_expect *exp_info;
+	struct ip_conntrack *master = master_ct(ct);
+
+	IP_NF_ASSERT(info);
+	IP_NF_ASSERT(master);
+
+	IP_NF_ASSERT(!(info->initialized & (1 << HOOK2MANIP(hooknum))));
+
+	DEBUGP("nat_expected: We have a connection!\n");
+	exp_info = &ct->master->help.exp_amanda_info;
+
+	newdstip = ct->tuplehash[IP_CT_DIR_REPLY].tuple.src.ip;
+	newsrcip = master->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.ip;
+	DEBUGP("nat_expected: %u.%u.%u.%u->%u.%u.%u.%u\n",
+	       NIPQUAD(newsrcip), NIPQUAD(newdstip));
+
+	port = exp_info->port;
+
+	if (HOOK2MANIP(hooknum) == IP_NAT_MANIP_SRC)
+		newip = newsrcip;
+	else
+		newip = newdstip;
+
+	DEBUGP("nat_expected: IP to %u.%u.%u.%u\n", NIPQUAD(newip));
+
+	mr.rangesize = 1;
+	/* We don't want to manip the per-protocol, just the IPs. */
+	mr.range[0].flags = IP_NAT_RANGE_MAP_IPS;
+	mr.range[0].min_ip = mr.range[0].max_ip = newip;
+
+	if (HOOK2MANIP(hooknum) == IP_NAT_MANIP_DST) {
+		mr.range[0].flags |= IP_NAT_RANGE_PROTO_SPECIFIED;
+		mr.range[0].min = mr.range[0].max
+			= ((union ip_conntrack_manip_proto)
+				{ htons(port) });
+	}
+
+	return ip_nat_setup_info(ct, &mr, hooknum);
+}
+
+static int amanda_data_fixup(struct ip_conntrack *ct,
+			  struct sk_buff **pskb,
+			  enum ip_conntrack_info ctinfo,
+			  struct ip_conntrack_expect *expect)
+{
+	u_int32_t newip;
+	/* DATA 99999 MESG 99999 INDEX 99999 */
+	char buffer[6];
+	struct ip_conntrack_expect *exp = expect;
+	struct ip_ct_amanda_expect *ct_amanda_info = &exp->help.exp_amanda_info;
+	struct ip_conntrack_tuple t = exp->tuple;
+	int port;
+
+	MUST_BE_LOCKED(&ip_amanda_lock);
+
+	newip = ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.dst.ip;
+	DEBUGP ("ip_nat_amanda_help: newip = %u.%u.%u.%u\n", NIPQUAD(newip));
+
+	/* Alter conntrack's expectations. */
+
+	/* We can read expect here without conntrack lock, since it's
+	   only set in ip_conntrack_amanda, with ip_amanda_lock held
+	   writable */
+
+	t.dst.ip = newip;
+	for (port = ct_amanda_info->port + 10; port != 0; port++) {
+		t.dst.u.tcp.port = htons(port);
+		if (ip_conntrack_change_expect(exp, &t) == 0)
+			break;
+	}
+
+	if (port == 0)
+		return 0;
+
+	sprintf(buffer, "%u", port);
+
+	return ip_nat_mangle_udp_packet(pskb, ct, ctinfo, /* XXX exp->seq */ ct_amanda_info->offset, 
+					ct_amanda_info->len, buffer, strlen(buffer));
+}
+
+static unsigned int help(struct ip_conntrack *ct,
+			 struct ip_conntrack_expect *exp,
+			 struct ip_nat_info *info,
+			 enum ip_conntrack_info ctinfo,
+			 unsigned int hooknum,
+			 struct sk_buff **pskb)
+{
+	int dir;
+
+	if (!exp)
+		DEBUGP("ip_nat_amanda: no exp!!");
+		
+	/* Only mangle things once: original direction in POST_ROUTING
+	   and reply direction on PRE_ROUTING. */
+	dir = CTINFO2DIR(ctinfo);
+	if (!((hooknum == NF_IP_POST_ROUTING && dir == IP_CT_DIR_ORIGINAL)
+	      || (hooknum == NF_IP_PRE_ROUTING && dir == IP_CT_DIR_REPLY))) {
+		DEBUGP("ip_nat_amanda_help: Not touching dir %s at hook %s\n",
+		       dir == IP_CT_DIR_ORIGINAL ? "ORIG" : "REPLY",
+		       hooknum == NF_IP_POST_ROUTING ? "POSTROUTING"
+		       : hooknum == NF_IP_PRE_ROUTING ? "PREROUTING"
+		       : hooknum == NF_IP_LOCAL_OUT ? "OUTPUT"
+		       : hooknum == NF_IP_LOCAL_IN ? "INPUT" : "???");
+		return NF_ACCEPT;
+	}
+	DEBUGP("ip_nat_amanda_help: got beyond not touching: dir %s at hook %s for expect: ",
+		   dir == IP_CT_DIR_ORIGINAL ? "ORIG" : "REPLY",
+		   hooknum == NF_IP_POST_ROUTING ? "POSTROUTING"
+		   : hooknum == NF_IP_PRE_ROUTING ? "PREROUTING"
+		     : hooknum == NF_IP_LOCAL_OUT ? "OUTPUT"
+		       : hooknum == NF_IP_LOCAL_IN ? "INPUT" : "???");
+	DUMP_TUPLE(&exp->tuple);
+
+	LOCK_BH(&ip_amanda_lock);
+// XXX	if (exp->seq != 0)
+	if (exp->help.exp_amanda_info.offset != 0)
+		/*  if this packet has a "seq" it needs to have it's content mangled */
+		if (!amanda_data_fixup(ct, pskb, ctinfo, exp)) {
+			UNLOCK_BH(&ip_amanda_lock);
+			DEBUGP("ip_nat_amanda: NF_DROP\n");
+			return NF_DROP;
+		}
+	exp->help.exp_amanda_info.offset = 0;
+	UNLOCK_BH(&ip_amanda_lock);
+
+	DEBUGP("ip_nat_amanda: NF_ACCEPT\n");
+	return NF_ACCEPT;
+}
+
+static struct ip_nat_helper ip_nat_amanda_helper;
+
+/* This function is intentionally _NOT_ defined as  __exit, because
+ * it is needed by init() */
+static void fini(void)
+{
+	DEBUGP("ip_nat_amanda: unregistering nat helper\n");
+	ip_nat_helper_unregister(&ip_nat_amanda_helper);
+}
+
+static int __init init(void)
+{
+	int ret = 0;
+	struct ip_nat_helper *hlpr;
+
+	hlpr = &ip_nat_amanda_helper;
+	memset(hlpr, 0, sizeof(struct ip_nat_helper));
+
+	hlpr->tuple.dst.protonum = IPPROTO_UDP;
+	hlpr->tuple.src.u.udp.port = htons(10080);
+	hlpr->mask.src.u.udp.port = 0xFFFF;
+	hlpr->mask.dst.protonum = 0xFFFF;
+	hlpr->help = help;
+	hlpr->flags = 0;
+	hlpr->me = THIS_MODULE;
+	hlpr->expect = amanda_nat_expected;
+
+	hlpr->name = "amanda";
+
+	DEBUGP
+	    ("ip_nat_amanda: Trying to register nat helper\n");
+	ret = ip_nat_helper_register(hlpr);
+
+	if (ret) {
+		printk
+		    ("ip_nat_amanda: error registering nat helper\n");
+		fini();
+		return 1;
+	}
+	return ret;
+}
+
+
+module_init(init);
+module_exit(fini);