[kernel] netfilter fixes for 2.6.23

 * fix compiler warnings in xt_CHAOS.c, xt_DELUDE.c, and in xt_portscan.c
 * make xt_TARPIT available as well


git-svn-id: svn://svn.openwrt.org/openwrt/trunk@9255 3c298f89-4303-0410-b956-a3cf2f4a3e73

2 files changed, 343 insertions, 17 deletions

diff --git a/target/linux/generic-2.6/patches-2.6.23/170-netfilter_chaostables.patch b/target/linux/generic-2.6/patches-2.6.23/170-netfilter_chaostables.patch
index 1c14c13ea8..cfc0092330 100644
--- a/target/linux/generic-2.6/patches-2.6.23/170-netfilter_chaostables.patch
+++ b/target/linux/generic-2.6/patches-2.6.23/170-netfilter_chaostables.patch
@@ -179,7 +179,7 @@ Index: linux-2.6.23/net/netfilter/xt_CHAOS.c
 ===================================================================
 --- /dev/null	1970-01-01 00:00:00.000000000 +0000
 +++ linux-2.6.23/net/netfilter/xt_CHAOS.c	2007-10-10 13:52:59.000000000 +0800
-@@ -0,0 +1,204 @@
+@@ -0,0 +1,205 @@
 +/*
 +	CHAOS target for netfilter
 +
@@ -233,7 +233,8 @@ Index: linux-2.6.23/net/netfilter/xt_CHAOS.c
 +	const int protoff = ip_hdrlen(*pskb);
 +	const int offset  = ntohs(ip_hdr(*pskb)->frag_off) & IP_OFFSET;
 +	const struct xt_target *destiny;
-+	int hotdrop = 0, ret;
++	bool hotdrop = false;
++	int ret;
 +
 +	ret = xm_tcp->match(*pskb, in, out, xm_tcp, &tcp_params,
 +	                    offset, protoff, &hotdrop);
@@ -284,7 +285,7 @@ Index: linux-2.6.23/net/netfilter/xt_CHAOS.c
 +	return NF_DROP;
 +}
 +
-+static int xt_chaos_checkentry(const char *tablename, const void *entry,
++static bool xt_chaos_checkentry(const char *tablename, const void *entry,
 +    const struct xt_target *target, void *targinfo,
 +#ifdef HAVE_TARGINFOSIZE
 +    unsigned int targinfosize,
@@ -295,14 +296,14 @@ Index: linux-2.6.23/net/netfilter/xt_CHAOS.c
 +	if(info->variant == XTCHAOS_DELUDE && !have_delude) {
 +		printk(KERN_WARNING PFX "Error: Cannot use --delude when "
 +		       "DELUDE module not available\n");
-+		return 0;
++		return false;
 +	}
 +	if(info->variant == XTCHAOS_TARPIT && !have_tarpit) {
 +		printk(KERN_WARNING PFX "Error: Cannot use --tarpit when "
 +		       "TARPIT module not available\n");
-+		return 0;
++		return false;
 +	}
-+	return 1;
++	return true;
 +}
 +
 +static struct xt_target xt_chaos_info = {
@@ -634,7 +635,7 @@ Index: linux-2.6.23/net/netfilter/xt_DELUDE.c
 +	return NF_DROP;
 +}
 +
-+static int xt_delude_check(const char *tablename, const void *e_void,
++static bool xt_delude_check(const char *tablename, const void *e_void,
 +    const struct xt_target *target, void *targinfo,
 +#ifdef HAVE_TARGINFOSIZE
 +    unsigned int targinfosize,
@@ -644,9 +645,9 @@ Index: linux-2.6.23/net/netfilter/xt_DELUDE.c
 +	if(hook_mask & ~((1 << NF_IP_LOCAL_IN) | (1 << NF_IP_FORWARD))) {
 +		printk(KERN_WARNING PFX "DELUDE may not be used in chains "
 +		       "other than INPUT and FORWARD\n");
-+		return 0;
++		return false;
 +	}
-+	return 1;
++	return true;
 +}
 +
 +static struct xt_target xt_delude_info = {
@@ -854,10 +855,10 @@ Index: linux-2.6.23/net/netfilter/xt_portscan.c
 +	return mark;
 +}
 +
-+static int xt_portscan_match(const struct sk_buff *skb,
++static bool xt_portscan_match(const struct sk_buff *skb,
 +    const struct net_device *in, const struct net_device *out,
 +    const struct xt_match *match, const void *matchinfo, int offset,
-+    unsigned int protoff, int *hotdrop)
++    unsigned int protoff, bool *hotdrop)
 +{
 +	const struct xt_portscan_info *info = matchinfo;
 +	enum ip_conntrack_info ctstate;
@@ -867,7 +868,7 @@ Index: linux-2.6.23/net/netfilter/xt_portscan.c
 +
 +	tcph = skb_header_pointer(skb, protoff, sizeof(tcph_buf), &tcph_buf);
 +	if(tcph == NULL)
-+		return 0;
++		return false;
 +
 +	/* Check for invalid packets: -m conntrack --ctstate INVALID */
 +	if((ctdata = nf_ct_get(skb, &ctstate)) == NULL) {
@@ -877,7 +878,7 @@ Index: linux-2.6.23/net/netfilter/xt_portscan.c
 +		 * If @ctdata is NULL, we cannot match the other scan
 +		 * types, return.
 +		 */
-+		return 0;
++		return false;
 +	}
 +
 +	/*
@@ -903,7 +904,7 @@ Index: linux-2.6.23/net/netfilter/xt_portscan.c
 +	       (info->match_gr && ctdata->mark == mark_grscan);
 +}
 +
-+static int xt_portscan_checkentry(const char *tablename, const void *entry,
++static bool xt_portscan_checkentry(const char *tablename, const void *entry,
 +    const struct xt_match *match, void *matchinfo,
 +#ifdef HAVE_MATCHINFOSIZE
 +    unsigned int matchinfosize,
@@ -916,15 +917,15 @@ Index: linux-2.6.23/net/netfilter/xt_portscan.c
 +		printk(KERN_WARNING PFX "matchinfosize %u != %Zu\n",
 +		       matchinfosize,
 +		       XT_ALIGN(sizeof(struct xt_portscan_info)));
-+		return 0;
++		return false;
 +	}
 +#endif
 +	if((info->match_stealth & ~1) || (info->match_syn & ~1) ||
 +	  (info->match_cn & ~1) || (info->match_gr & ~1)) {
 +		printk(KERN_WARNING PFX "Invalid flags\n");
-+		return 0;
++		return false;
 +	}
-+	return 1;
++	return true;
 +}
 +
 +static struct xt_match xt_portscan = {
diff --git a/target/linux/generic-2.6/patches-2.6.23/171-netfilter_tarpit.patch b/target/linux/generic-2.6/patches-2.6.23/171-netfilter_tarpit.patch
new file mode 100644
index 0000000000..058dda5c28
--- /dev/null
+++ b/target/linux/generic-2.6/patches-2.6.23/171-netfilter_tarpit.patch
@@ -0,0 +1,325 @@
+Index: linux-2.6.23/net/netfilter/Kconfig
+===================================================================
+--- linux-2.6.23.orig/net/netfilter/Kconfig
++++ linux-2.6.23/net/netfilter/Kconfig
+@@ -401,6 +401,23 @@ config NETFILTER_XT_TARGET_CONNSECMARK
+ 
+ 	  To compile it as a module, choose M here.  If unsure, say N.
+ 
++config NETFILTER_XT_TARGET_TARPIT
++	tristate '"TARPIT" target support'
++	depends on NETFILTER_XTABLES
++	---help---
++	  Adds a TARPIT target to iptables, which captures and holds
++	  incoming TCP connections using no local per-connection resources.
++	  Connections are accepted, but immediately switched to the persist
++	  state (0 byte window), in which the remote side stops sending data
++	  and asks to continue every 60-240 seconds. Attempts to close the
++	  connection are ignored, forcing the remote side to time out the
++	  connection in 12-24 minutes.
++
++	  This offers similar functionality to LaBrea
++	  <http://www.hackbusters.net/LaBrea/>, but does not require dedicated
++	  hardware or IPs. Any TCP port that you would normally DROP or REJECT
++	  can instead become a tarpit.
++
+ config NETFILTER_XT_TARGET_TCPMSS
+ 	tristate '"TCPMSS" target support'
+ 	depends on NETFILTER_XTABLES && (IPV6 || IPV6=n)
+Index: linux-2.6.23/net/netfilter/Makefile
+===================================================================
+--- linux-2.6.23.orig/net/netfilter/Makefile
++++ linux-2.6.23/net/netfilter/Makefile
+@@ -49,6 +49,7 @@ obj-$(CONFIG_NETFILTER_XT_TARGET_NFLOG) 
+ obj-$(CONFIG_NETFILTER_XT_TARGET_NOTRACK) += xt_NOTRACK.o
+ obj-$(CONFIG_NETFILTER_XT_TARGET_TRACE) += xt_TRACE.o
+ obj-$(CONFIG_NETFILTER_XT_TARGET_SECMARK) += xt_SECMARK.o
++obj-$(CONFIG_NETFILTER_XT_TARGET_TARPIT) += xt_TARPIT.o
+ obj-$(CONFIG_NETFILTER_XT_TARGET_TCPMSS) += xt_TCPMSS.o
+ obj-$(CONFIG_NETFILTER_XT_TARGET_CONNSECMARK) += xt_CONNSECMARK.o
+ 
+Index: linux-2.6.23/net/netfilter/xt_TARPIT.c
+===================================================================
+--- /dev/null
++++ linux-2.6.23/net/netfilter/xt_TARPIT.c
+@@ -0,0 +1,280 @@
++/*
++ * Kernel module to capture and hold incoming TCP connections using
++ * no local per-connection resources.
++ *
++ * Based on ipt_REJECT.c and offering functionality similar to
++ * LaBrea <http://www.hackbusters.net/LaBrea/>.
++ *
++ * Copyright (c) 2002 Aaron Hopkins <tools@die.net>
++ *
++ * 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.
++ *
++ * This program is distributed in the hope that it will be useful,
++ * but WITHOUT ANY WARRANTY; without even the implied warranty of
++ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
++ * GNU General Public License for more details.
++ *
++ * You should have received a copy of the GNU General Public License
++ * along with this program; if not, write to the Free Software
++ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
++ *
++ * Goal:
++ * - Allow incoming TCP connections to be established.
++ * - Passing data should result in the connection being switched to the
++ *   persist state (0 byte window), in which the remote side stops sending
++ *   data and asks to continue every 60 seconds.
++ * - Attempts to shut down the connection should be ignored completely, so
++ *   the remote side ends up having to time it out.
++ *
++ * This means:
++ * - Reply to TCP SYN,!ACK,!RST,!FIN with SYN-ACK, window 5 bytes
++ * - Reply to TCP SYN,ACK,!RST,!FIN with RST to prevent spoofing
++ * - Reply to TCP !SYN,!RST,!FIN with ACK, window 0 bytes, rate-limited
++ */
++
++#include <linux/version.h>
++#include <linux/module.h>
++#include <linux/skbuff.h>
++#include <linux/ip.h>
++#include <net/ip.h>
++#include <net/tcp.h>
++#include <net/icmp.h>
++struct in_device;
++#include <net/route.h>
++#include <linux/random.h>
++#include <linux/netfilter_ipv4/ip_tables.h>
++
++#if 0
++#define DEBUGP printk
++#else
++#define DEBUGP(format, args...)
++#endif
++
++/* Stolen from ip_finish_output2 */
++static int ip_direct_send(struct sk_buff *skb)
++{
++	struct dst_entry *dst = skb->dst;
++
++        if (dst->hh != NULL)
++		return neigh_hh_output(dst->hh, skb);
++	else if (dst->neighbour != NULL)
++		return dst->neighbour->output(skb);
++
++	if (net_ratelimit())
++		printk(KERN_DEBUG "TARPIT ip_direct_send: no header cache and no neighbor!\n");
++
++	kfree_skb(skb);
++	return -EINVAL;
++}
++
++
++/* Send reply */
++static void tarpit_tcp(const struct sk_buff *oskb, struct rtable *ort,
++                       unsigned int local)
++{
++	struct sk_buff *nskb;
++	struct rtable *nrt;
++	struct tcphdr *otcph, *ntcph;
++	struct flowi fl = {};
++	unsigned int otcplen;
++	u_int16_t tmp;
++
++	const struct iphdr *oiph = ip_hdr(oskb);
++	struct iphdr *niph;
++
++	/* A truncated TCP header is not going to be useful */
++	if (oskb->len < ip_hdrlen(oskb) + sizeof(struct tcphdr))
++		return;
++
++	otcph   = (void *)oiph + ip_hdrlen(oskb);
++	otcplen = oskb->len - ip_hdrlen(oskb);
++
++	/* No replies for RST or FIN */
++	if (otcph->rst || otcph->fin)
++		return;
++
++	/* No reply to !SYN,!ACK.  Rate-limit replies to !SYN,ACKs */
++	if (!otcph->syn && (!otcph->ack || !xrlim_allow(&ort->u.dst, 1*HZ)))
++		return;
++
++	/* Check checksum. */
++	if (tcp_v4_check(otcplen, oiph->saddr, oiph->daddr,
++	    csum_partial((char *)otcph, otcplen, 0)) != 0)
++		return;
++
++	/*
++	 * Copy skb (even if skb is about to be dropped, we cannot just
++	 * clone it because there may be other things, such as tcpdump,
++	 * interested in it)
++	 */
++	nskb = skb_copy(oskb, GFP_ATOMIC);
++	if (nskb == NULL)
++		return;
++
++	niph = ip_hdr(nskb);
++
++	/* This packet will not be the same as the other: clear nf fields */
++	nf_conntrack_put(nskb->nfct);
++	nskb->nfct = NULL;
++#ifdef CONFIG_NETFILTER_DEBUG
++	nskb->nf_debug = 0;
++#endif
++
++	ntcph = (void *)niph + ip_hdrlen(nskb);
++
++	/* Truncate to length (no data) */
++	ntcph->doff = sizeof(struct tcphdr)/4;
++	skb_trim(nskb, ip_hdrlen(nskb) + sizeof(struct tcphdr));
++	niph->tot_len = htons(nskb->len);
++
++	/* Swap source and dest */
++	niph->daddr = xchg(&niph->saddr, niph->daddr);
++	tmp = ntcph->source;
++	ntcph->source = ntcph->dest;
++	ntcph->dest = tmp;
++
++	/* Use supplied sequence number or make a new one */
++	ntcph->seq = otcph->ack ? otcph->ack_seq
++		: htonl(secure_tcp_sequence_number(niph->saddr,
++						   niph->daddr,
++						   ntcph->source,
++						   ntcph->dest));
++
++	/* Our SYN-ACKs must have a >0 window */
++	ntcph->window = (otcph->syn && !otcph->ack) ? htons(5) : 0;
++
++	ntcph->urg_ptr = 0;
++
++	/* Reset flags */
++	((u_int8_t *)ntcph)[13] = 0;
++
++	if (otcph->syn && otcph->ack) {
++		ntcph->rst = 1;
++		ntcph->ack_seq = 0;
++	} else {
++		ntcph->syn = otcph->syn;
++		ntcph->ack = 1;
++		ntcph->ack_seq = htonl(ntohl(otcph->seq) + otcph->syn);
++	}
++
++	/* Adjust TCP checksum */
++	ntcph->check = 0;
++	ntcph->check = tcp_v4_check(sizeof(struct tcphdr),
++				   niph->saddr,
++				   niph->daddr,
++				   csum_partial((char *)ntcph,
++						sizeof(struct tcphdr), 0));
++
++	fl.nl_u.ip4_u.daddr = niph->daddr;
++	fl.nl_u.ip4_u.saddr = local ? niph->saddr : 0;
++	fl.nl_u.ip4_u.tos = RT_TOS(niph->tos) | RTO_CONN;
++	fl.oif = 0;
++
++	if (ip_route_output_key(&nrt, &fl))
++		goto free_nskb;
++
++	dst_release(nskb->dst);
++	nskb->dst = &nrt->u.dst;
++
++	/* Adjust IP TTL */
++	niph->ttl = dst_metric(nskb->dst, RTAX_HOPLIMIT);
++
++	/* Set DF, id = 0 */
++	niph->frag_off = htons(IP_DF);
++	niph->id = 0;
++
++	/* Adjust IP checksum */
++	niph->check = 0;
++	niph->check = ip_fast_csum((unsigned char *)niph, niph->ihl);
++
++	/* "Never happens" */
++	if (nskb->len > dst_mtu(nskb->dst))
++		goto free_nskb;
++
++	ip_direct_send(nskb);
++	return;
++
++ free_nskb:
++	kfree_skb(nskb);
++}
++
++static unsigned int xt_tarpit_target(struct sk_buff **pskb,
++                                     const struct net_device *in,
++                                     const struct net_device *out,
++                                     unsigned int hooknum,
++                                     const struct xt_target *target,
++                                     const void *targinfo)
++{
++	const struct sk_buff *skb = *pskb;
++	const struct iphdr *iph   = ip_hdr(skb);
++	struct rtable *rt         = (void *)skb->dst;
++
++	/* Do we have an input route cache entry? */
++	if (rt == NULL)
++		return NF_DROP;
++
++	/* No replies to physical multicast/broadcast */
++	if (skb->pkt_type != PACKET_HOST && skb->pkt_type != PACKET_OTHERHOST)
++		return NF_DROP;
++
++	/* Now check at the protocol level */
++	if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST))
++		return NF_DROP;
++
++	/*
++	 * Our naive response construction does not deal with IP
++	 * options, and probably should not try.
++	 */
++	if (iph->ihl * 4 != sizeof(struct iphdr))
++		return NF_DROP;
++
++	/* We are not interested in fragments */
++	if (iph->frag_off & htons(IP_OFFSET))
++		return NF_DROP;
++
++	tarpit_tcp(skb, rt, hooknum == NF_IP_LOCAL_IN);
++	return NF_DROP;
++}
++
++static bool xt_tarpit_check(const char *tablename, const void *entry,
++                            const struct xt_target *target, void *targinfo,
++                            unsigned int hook_mask)
++{
++	bool invalid;
++
++	if (strcmp(tablename, "raw") == 0 && hook_mask == NF_IP_PRE_ROUTING)
++		return true;
++	if (strcmp(tablename, "filter") != 0)
++		return false;
++	invalid = hook_mask & ~((1 << NF_IP_LOCAL_IN) | (1 << NF_IP_FORWARD));
++	return !invalid;
++}
++
++static struct xt_target xt_tarpit_reg = {
++	.name       = "TARPIT",
++	.family     = AF_INET,
++	.proto      = IPPROTO_TCP,
++	.target     = xt_tarpit_target,
++	.checkentry = xt_tarpit_check,
++	.me         = THIS_MODULE,
++};
++
++static int __init xt_tarpit_init(void)
++{
++	return xt_register_target(&xt_tarpit_reg);
++}
++
++static void __exit xt_tarpit_exit(void)
++{
++	xt_unregister_target(&xt_tarpit_reg);
++}
++
++module_init(xt_tarpit_init);
++module_exit(xt_tarpit_exit);
++MODULE_DESCRIPTION("netfilter xt_TARPIT target module");
++MODULE_AUTHOR("Jan Engelhardt <jengelh@gmx.de>");
++MODULE_LICENSE("GPL");
++MODULE_ALIAS("ipt_TARPIT");