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Index: linux-2.6.21.7/include/linux/netfilter/oot_conntrack.h
===================================================================
--- /dev/null
+++ linux-2.6.21.7/include/linux/netfilter/oot_conntrack.h
@@ -0,0 +1,5 @@
+#if defined(CONFIG_IP_NF_CONNTRACK) || defined(CONFIG_IP_NF_CONNTRACK_MODULE)
+# include <linux/netfilter_ipv4/ip_conntrack.h>
+#else /* linux-2.6.20+ */
+# include <net/netfilter/nf_nat_rule.h>
+#endif
Index: linux-2.6.21.7/include/linux/netfilter/oot_trans.h
===================================================================
--- /dev/null
+++ linux-2.6.21.7/include/linux/netfilter/oot_trans.h
@@ -0,0 +1,14 @@
+/* Out of tree workarounds */
+#include <linux/version.h>
+#if LINUX_VERSION_CODE <= KERNEL_VERSION(2, 6, 18)
+# define HAVE_MATCHINFOSIZE 1
+# define HAVE_TARGUSERINFO 1
+# define HAVE_TARGINFOSIZE 1
+#endif
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2, 6, 20)
+# define nfmark mark
+#endif
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2, 6, 21)
+# define tcp_v4_check(tcph, tcph_sz, s, d, csp) \
+ tcp_v4_check((tcph_sz), (s), (d), (csp))
+#endif
Index: linux-2.6.21.7/include/linux/netfilter/xt_CHAOS.h
===================================================================
--- /dev/null
+++ linux-2.6.21.7/include/linux/netfilter/xt_CHAOS.h
@@ -0,0 +1,14 @@
+#ifndef _LINUX_NETFILTER_XT_CHAOS_H
+#define _LINUX_NETFILTER_XT_CHAOS_H 1
+
+enum xt_chaos_target_variant {
+ XTCHAOS_NORMAL,
+ XTCHAOS_TARPIT,
+ XTCHAOS_DELUDE,
+};
+
+struct xt_chaos_target_info {
+ uint8_t variant;
+};
+
+#endif /* _LINUX_NETFILTER_XT_CHAOS_H */
Index: linux-2.6.21.7/include/linux/netfilter/xt_portscan.h
===================================================================
--- /dev/null
+++ linux-2.6.21.7/include/linux/netfilter/xt_portscan.h
@@ -0,0 +1,8 @@
+#ifndef _LINUX_NETFILTER_XT_PORTSCAN_H
+#define _LINUX_NETFILTER_XT_PORTSCAN_H 1
+
+struct xt_portscan_match_info {
+ uint8_t match_stealth, match_syn, match_cn, match_gr;
+};
+
+#endif /* _LINUX_NETFILTER_XT_PORTSCAN_H */
Index: linux-2.6.21.7/net/netfilter/find_match.c
===================================================================
--- /dev/null
+++ linux-2.6.21.7/net/netfilter/find_match.c
@@ -0,0 +1,39 @@
+/*
+ xt_request_find_match
+ by Jan Engelhardt <jengelh [at] gmx de>, 2006 - 2007
+
+ Based upon linux-2.6.18.5/net/netfilter/x_tables.c:
+ Copyright (C) 2006-2006 Harald Welte <laforge@netfilter.org>
+ This program is free software; you can redistribute it and/or modify
+ it under the terms of the GNU General Public License version 2 as
+ published by the Free Software Foundation.
+*/
+#include <linux/err.h>
+#include <linux/netfilter_arp.h>
+#include <linux/socket.h>
+#include <linux/netfilter/x_tables.h>
+
+/*
+ * Yeah this code is sub-optimal, but the function is missing in
+ * mainline so far. -jengelh
+ */
+static struct xt_match *xt_request_find_match_lo(int af, const char *name,
+ u8 revision)
+{
+ static const char *const xt_prefix[] = {
+ [AF_INET] = "ip",
+ [AF_INET6] = "ip6",
+ [NF_ARP] = "arp",
+ };
+ struct xt_match *match;
+
+ match = try_then_request_module(xt_find_match(af, name, revision),
+ "%st_%s", xt_prefix[af], name);
+ if (IS_ERR(match) || match == NULL)
+ return NULL;
+
+ return match;
+}
+
+/* In case it goes into mainline, let this out-of-tree package compile */
+#define xt_request_find_match xt_request_find_match_lo
Index: linux-2.6.21.7/net/netfilter/Kconfig
===================================================================
--- linux-2.6.21.7.orig/net/netfilter/Kconfig
+++ linux-2.6.21.7/net/netfilter/Kconfig
@@ -287,6 +287,14 @@ config NETFILTER_XTABLES
# alphabetically ordered list of targets
+config NETFILTER_XT_TARGET_CHAOS
+ tristate '"CHAOS" target support'
+ depends on NETFILTER_XTABLES
+ help
+ This option adds a `CHAOS' target.
+
+ To compile it as a module, choose M here. If unsure, say N.
+
config NETFILTER_XT_TARGET_CLASSIFY
tristate '"CLASSIFY" target support'
depends on NETFILTER_XTABLES
@@ -315,6 +323,14 @@ config NETFILTER_XT_TARGET_CONNMARK
<file:Documentation/modules.txt>. The module will be called
ipt_CONNMARK.o. If unsure, say `N'.
+config NETFILTER_XT_TARGET_DELUDE
+ tristate '"DELUDE" target support'
+ depends on NETFILTER_XTABLES
+ help
+ This option adds a `DELUDE' target.
+
+ To compile it as a module, choose M here. If unsure, say N.
+
config NETFILTER_XT_TARGET_DSCP
tristate '"DSCP" target support'
depends on NETFILTER_XTABLES
@@ -563,6 +579,14 @@ config NETFILTER_XT_MATCH_POLICY
To compile it as a module, choose M here. If unsure, say N.
+config NETFILTER_XT_MATCH_PORTSCAN
+ tristate '"portscan" match support'
+ depends on NETFILTER_XTABLES
+ help
+ This option adds a 'portscan' match support.
+
+ To compile it as a module, choose M here. If unsure, say N.
+
config NETFILTER_XT_MATCH_MULTIPORT
tristate "Multiple port match support"
depends on NETFILTER_XTABLES
Index: linux-2.6.21.7/net/netfilter/Makefile
===================================================================
--- linux-2.6.21.7.orig/net/netfilter/Makefile
+++ linux-2.6.21.7/net/netfilter/Makefile
@@ -47,6 +47,8 @@ obj-$(CONFIG_NETFILTER_XT_TARGET_NOTRACK
obj-$(CONFIG_NETFILTER_XT_TARGET_SECMARK) += xt_SECMARK.o
obj-$(CONFIG_NETFILTER_XT_TARGET_TCPMSS) += xt_TCPMSS.o
obj-$(CONFIG_NETFILTER_XT_TARGET_CONNSECMARK) += xt_CONNSECMARK.o
+obj-$(CONFIG_NETFILTER_XT_TARGET_CHAOS) += xt_CHAOS.o
+obj-$(CONFIG_NETFILTER_XT_TARGET_DELUDE) += xt_DELUDE.o
# matches
obj-$(CONFIG_NETFILTER_XT_MATCH_COMMENT) += xt_comment.o
@@ -74,3 +76,4 @@ obj-$(CONFIG_NETFILTER_XT_MATCH_STRING)
obj-$(CONFIG_NETFILTER_XT_MATCH_TCPMSS) += xt_tcpmss.o
obj-$(CONFIG_NETFILTER_XT_MATCH_PHYSDEV) += xt_physdev.o
obj-$(CONFIG_NETFILTER_XT_MATCH_HASHLIMIT) += xt_hashlimit.o
+obj-$(CONFIG_NETFILTER_XT_MATCH_PORTSCAN) += xt_portscan.o
Index: linux-2.6.21.7/net/netfilter/xt_CHAOS.c
===================================================================
--- /dev/null
+++ linux-2.6.21.7/net/netfilter/xt_CHAOS.c
@@ -0,0 +1,200 @@
+/*
+ * CHAOS target for netfilter
+ * Copyright © CC Computer Consultants GmbH, 2006 - 2007
+ * Contact: Jan Engelhardt <jengelh@computergmbh.de>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License; either version
+ * 2 or 3 as published by the Free Software Foundation.
+ */
+#include <linux/icmp.h>
+#include <linux/in.h>
+#include <linux/ip.h>
+#include <linux/module.h>
+#include <linux/skbuff.h>
+#include <linux/stat.h>
+#include <linux/netfilter/x_tables.h>
+#include <linux/netfilter/xt_tcpudp.h>
+#include <linux/netfilter_ipv4/ipt_REJECT.h>
+#include <net/ip.h>
+#if defined(_LOCAL)
+# include "xt_CHAOS.h"
+# include "find_match.c"
+#elif defined(CONFIG_NETFILTER_XT_TARGET_CHAOS) || \
+ defined(CONFIG_NETFILTER_XT_TARGET_CHAOS_MODULE)
+# include <linux/netfilter/xt_CHAOS.h>
+# include "find_match.c"
+#else
+# include "xt_CHAOS.h"
+# include "find_match.c"
+#endif
+#define PFX KBUILD_MODNAME ": "
+
+/* Module parameters */
+static unsigned int reject_percentage = ~0U * .01;
+static unsigned int delude_percentage = ~0U * .0101;
+module_param(reject_percentage, uint, S_IRUGO | S_IWUSR);
+module_param(delude_percentage, uint, S_IRUGO | S_IWUSR);
+
+/* References to other matches/targets */
+static struct xt_match *xm_tcp;
+static struct xt_target *xt_delude, *xt_reject, *xt_tarpit;
+
+static int have_delude, have_tarpit;
+
+/* Static data for other matches/targets */
+static const struct ipt_reject_info reject_params = {
+ .with = ICMP_HOST_UNREACH,
+};
+
+static const struct xt_tcp tcp_params = {
+ .spts = {0, ~0},
+ .dpts = {0, ~0},
+};
+
+/* CHAOS functions */
+static void xt_chaos_total(const struct xt_chaos_target_info *info,
+ struct sk_buff **pskb, const struct net_device *in,
+ const struct net_device *out, unsigned int hooknum)
+{
+ const struct iphdr *iph = ip_hdr(*pskb);
+ const int protoff = 4 * iph->ihl;
+ const int offset = ntohs(iph->frag_off) & IP_OFFSET;
+ const struct xt_target *destiny;
+ int hotdrop = 0, ret;
+
+ ret = xm_tcp->match(*pskb, in, out, xm_tcp, &tcp_params,
+ offset, protoff, &hotdrop);
+ if (!ret || hotdrop || (unsigned int)net_random() > delude_percentage)
+ return;
+
+ destiny = (info->variant == XTCHAOS_TARPIT) ? xt_tarpit : xt_delude;
+ destiny->target(pskb, in, out, hooknum, destiny, NULL);
+ return;
+}
+
+static unsigned int chaos_tg(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)
+{
+ /*
+ * Equivalent to:
+ * -A chaos -m statistic --mode random --probability \
+ * $reject_percentage -j REJECT --reject-with host-unreach;
+ * -A chaos -p tcp -m statistic --mode random --probability \
+ * $delude_percentage -j DELUDE;
+ * -A chaos -j DROP;
+ */
+ const struct xt_chaos_target_info *info = targinfo;
+ const struct iphdr *iph = ip_hdr(*pskb);
+
+ if ((unsigned int)net_random() <= reject_percentage)
+ return xt_reject->target(pskb, in, out, hooknum, target,
+ &reject_params);
+
+ /* TARPIT/DELUDE may not be called from the OUTPUT chain */
+ if (iph->protocol == IPPROTO_TCP &&
+ info->variant != XTCHAOS_NORMAL && hooknum != NF_IP_LOCAL_OUT)
+ xt_chaos_total(info, pskb, in, out, hooknum);
+
+ return NF_DROP;
+}
+
+static int chaos_tg_check(const char *tablename, const void *entry,
+ const struct xt_target *target, void *targinfo, unsigned int hook_mask)
+{
+ const struct xt_chaos_target_info *info = targinfo;
+
+ if (info->variant == XTCHAOS_DELUDE && !have_delude) {
+ printk(KERN_WARNING PFX "Error: Cannot use --delude when "
+ "DELUDE module not available\n");
+ return false;
+ }
+ if (info->variant == XTCHAOS_TARPIT && !have_tarpit) {
+ printk(KERN_WARNING PFX "Error: Cannot use --tarpit when "
+ "TARPIT module not available\n");
+ return false;
+ }
+
+ return true;
+}
+
+static struct xt_target chaos_tg_reg = {
+ .name = "CHAOS",
+ .family = AF_INET,
+ .table = "filter",
+ .hooks = (1 << NF_IP_LOCAL_IN) | (1 << NF_IP_FORWARD) |
+ (1 << NF_IP_LOCAL_OUT),
+ .checkentry = chaos_tg_check,
+ .target = chaos_tg,
+ .targetsize = sizeof(struct xt_chaos_target_info),
+ .me = THIS_MODULE,
+};
+
+static int __init chaos_tg_init(void)
+{
+ int ret = -EINVAL;
+
+ xm_tcp = xt_request_find_match(AF_INET, "tcp", 0);
+ if (xm_tcp == NULL) {
+ printk(KERN_WARNING PFX "Error: Could not find or load "
+ "\"tcp\" match\n");
+ return -EINVAL;
+ }
+
+ xt_reject = xt_request_find_target(AF_INET, "REJECT", 0);
+ if (xt_reject == NULL) {
+ printk(KERN_WARNING PFX "Error: Could not find or load "
+ "\"REJECT\" target\n");
+ goto out2;
+ }
+
+ xt_tarpit = xt_request_find_target(AF_INET, "TARPIT", 0);
+ have_tarpit = xt_tarpit != NULL;
+ if (!have_tarpit)
+ printk(KERN_WARNING PFX "Warning: Could not find or load "
+ "\"TARPIT\" target\n");
+
+ xt_delude = xt_request_find_target(AF_INET, "DELUDE", 0);
+ have_delude = xt_delude != NULL;
+ if (!have_delude)
+ printk(KERN_WARNING PFX "Warning: Could not find or load "
+ "\"DELUDE\" target\n");
+
+ if ((ret = xt_register_target(&chaos_tg_reg)) != 0) {
+ printk(KERN_WARNING PFX "xt_register_target returned "
+ "error %d\n", ret);
+ goto out3;
+ }
+
+ return 0;
+
+ out3:
+ if (have_delude)
+ module_put(xt_delude->me);
+ if (have_tarpit)
+ module_put(xt_tarpit->me);
+ module_put(xt_reject->me);
+ out2:
+ module_put(xm_tcp->me);
+ return ret;
+}
+
+static void __exit chaos_tg_exit(void)
+{
+ xt_unregister_target(&chaos_tg_reg);
+ module_put(xm_tcp->me);
+ module_put(xt_reject->me);
+ if (have_delude)
+ module_put(xt_delude->me);
+ if (have_tarpit)
+ module_put(xt_tarpit->me);
+ return;
+}
+
+module_init(chaos_tg_init);
+module_exit(chaos_tg_exit);
+MODULE_AUTHOR("Jan Engelhardt <jengelh@computergmbh.de>");
+MODULE_DESCRIPTION("netfilter \"CHAOS\" target");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("ipt_CHAOS");
Index: linux-2.6.21.7/net/netfilter/xt_DELUDE.c
===================================================================
--- /dev/null
+++ linux-2.6.21.7/net/netfilter/xt_DELUDE.c
@@ -0,0 +1,197 @@
+/*
+ * DELUDE target
+ * Copyright © CC Computer Consultants GmbH, 2007
+ * Contact: Jan Engelhardt <jengelh@computergmbh.de>
+ *
+ * Based upon linux-2.6.18.5/net/ipv4/netfilter/ipt_REJECT.c:
+ * (C) 1999-2001 Paul `Rusty' Russell
+ * (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org>
+ *
+ * xt_DELUDE acts like REJECT, but does reply with SYN-ACK on SYN.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+#include <linux/module.h>
+#include <linux/skbuff.h>
+#include <linux/ip.h>
+#include <linux/tcp.h>
+#include <linux/netfilter/x_tables.h>
+#ifdef CONFIG_BRIDGE_NETFILTER
+# include <linux/netfilter_bridge.h>
+#endif
+#include <net/tcp.h>
+#define PFX KBUILD_MODNAME ": "
+
+static void delude_send_reset(struct sk_buff *oldskb, unsigned int hook)
+{
+ struct tcphdr _otcph, *oth, *tcph;
+ unsigned int addr_type;
+ struct sk_buff *nskb;
+ u_int16_t tmp_port;
+ u_int32_t tmp_addr;
+ struct iphdr *niph;
+ bool needs_ack;
+
+ /* IP header checks: fragment. */
+ if (ip_hdr(oldskb)->frag_off & htons(IP_OFFSET))
+ return;
+
+ oth = skb_header_pointer(oldskb, ip_hdrlen(oldskb),
+ sizeof(_otcph), &_otcph);
+ if (oth == NULL)
+ return;
+
+ /* No RST for RST. */
+ if (oth->rst)
+ return;
+
+ /* Check checksum */
+ if (nf_ip_checksum(oldskb, hook, ip_hdrlen(oldskb), IPPROTO_TCP))
+ return;
+
+ /* We need a linear, writeable skb. We also need to expand
+ headroom in case hh_len of incoming interface < hh_len of
+ outgoing interface */
+ nskb = skb_copy_expand(oldskb, LL_MAX_HEADER, skb_tailroom(oldskb),
+ GFP_ATOMIC);
+ if (!nskb)
+ return;
+
+ /* This packet will not be the same as the other: clear nf fields */
+ nf_reset(nskb);
+ nskb->mark = 0;
+ skb_init_secmark(nskb);
+
+ skb_shinfo(nskb)->gso_size = 0;
+ skb_shinfo(nskb)->gso_segs = 0;
+ skb_shinfo(nskb)->gso_type = 0;
+
+ tcph = (struct tcphdr *)(skb_network_header(nskb) + ip_hdrlen(nskb));
+
+ /* Swap source and dest */
+ niph = ip_hdr(nskb);
+ tmp_addr = niph->saddr;
+ niph->saddr = niph->daddr;
+ niph->daddr = tmp_addr;
+ tmp_port = tcph->source;
+ tcph->source = tcph->dest;
+ tcph->dest = tmp_port;
+
+ /* Truncate to length (no data) */
+ tcph->doff = sizeof(struct tcphdr) / 4;
+ skb_trim(nskb, ip_hdrlen(nskb) + sizeof(struct tcphdr));
+ niph->tot_len = htons(nskb->len);
+
+ if (oth->syn && !oth->ack && !oth->rst && !oth->fin) {
+ /* DELUDE essential part */
+ tcph->ack_seq = htonl(ntohl(oth->seq) + oth->syn + oth->fin +
+ oldskb->len - ip_hdrlen(oldskb) -
+ (oth->doff << 2));
+ tcph->seq = false;
+ tcph->ack = true;
+ } else {
+ if (!tcph->ack) {
+ needs_ack = true;
+ tcph->ack_seq = htonl(ntohl(oth->seq) + oth->syn +
+ oth->fin + oldskb->len -
+ ip_hdrlen(oldskb) - (oth->doff<<2));
+ tcph->seq = false;
+ } else {
+ needs_ack = false;
+ tcph->seq = oth->ack_seq;
+ tcph->ack_seq = false;
+ }
+
+ /* Reset flags */
+ ((u_int8_t *)tcph)[13] = 0;
+ tcph->rst = true;
+ tcph->ack = needs_ack;
+ }
+
+ tcph->window = 0;
+ tcph->urg_ptr = 0;
+
+ /* Adjust TCP checksum */
+ tcph->check = 0;
+ tcph->check = tcp_v4_check(sizeof(struct tcphdr), niph->saddr,
+ niph->daddr, csum_partial((char *)tcph,
+ sizeof(struct tcphdr), 0));
+
+ /* Set DF, id = 0 */
+ niph->frag_off = htons(IP_DF);
+ niph->id = 0;
+
+ addr_type = RTN_UNSPEC;
+#ifdef CONFIG_BRIDGE_NETFILTER
+ if (hook != NF_IP_FORWARD || (nskb->nf_bridge != NULL &&
+ nskb->nf_bridge->mask & BRNF_BRIDGED))
+#else
+ if (hook != NF_IP_FORWARD)
+#endif
+ addr_type = RTN_LOCAL;
+
+ if (ip_route_me_harder(&nskb, addr_type))
+ goto free_nskb;
+
+ nskb->ip_summed = CHECKSUM_NONE;
+
+ /* Adjust IP TTL */
+ niph->ttl = dst_metric(nskb->dst, RTAX_HOPLIMIT);
+
+ /* Adjust IP checksum */
+ niph->check = 0;
+ niph->check = ip_fast_csum(skb_network_header(nskb), niph->ihl);
+
+ /* "Never happens" */
+ if (nskb->len > dst_mtu(nskb->dst))
+ goto free_nskb;
+
+ nf_ct_attach(nskb, oldskb);
+
+ NF_HOOK(PF_INET, NF_IP_LOCAL_OUT, nskb, NULL, nskb->dst->dev,
+ dst_output);
+ return;
+
+ free_nskb:
+ kfree_skb(nskb);
+}
+
+static unsigned int delude_tg(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)
+{
+ /* WARNING: This code causes reentry within iptables.
+ This means that the iptables jump stack is now crap. We
+ must return an absolute verdict. --RR */
+ delude_send_reset(*pskb, hooknum);
+ return NF_DROP;
+}
+
+static struct xt_target delude_tg_reg = {
+ .name = "DELUDE",
+ .family = AF_INET,
+ .table = "filter",
+ .hooks = (1 << NF_IP_LOCAL_IN) | (1 << NF_IP_FORWARD),
+ .target = delude_tg,
+ .proto = IPPROTO_TCP,
+ .me = THIS_MODULE,
+};
+
+static int __init delude_tg_init(void)
+{
+ return xt_register_target(&delude_tg_reg);
+}
+
+static void __exit delude_tg_exit(void)
+{
+ xt_unregister_target(&delude_tg_reg);
+}
+
+module_init(delude_tg_init);
+module_exit(delude_tg_exit);
+MODULE_AUTHOR("Jan Engelhardt <jengelh@computergmbh.de>");
+MODULE_DESCRIPTION("netfilter \"DELUDE\" target");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("ipt_DELUDE");
Index: linux-2.6.21.7/net/netfilter/xt_portscan.c
===================================================================
--- /dev/null
+++ linux-2.6.21.7/net/netfilter/xt_portscan.c
@@ -0,0 +1,269 @@
+/*
+ * portscan match for netfilter
+ * Copyright © CC Computer Consultants GmbH, 2006 - 2007
+ * Contact: Jan Engelhardt <jengelh@computergmbh.de>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License; either version
+ * 2 or 3 as published by the Free Software Foundation.
+ */
+#include <linux/in.h>
+#include <linux/ip.h>
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/skbuff.h>
+#include <linux/stat.h>
+#include <linux/tcp.h>
+#include <linux/types.h>
+#include <linux/version.h>
+#include <linux/netfilter/x_tables.h>
+#include <linux/netfilter/xt_tcpudp.h>
+#include <net/netfilter/nf_nat_rule.h>
+#if defined(_LOCAL)
+# include "xt_portscan.h"
+#elif defined(CONFIG_NETFILTER_XT_MATCH_PORTSCAN) || \
+ defined(CONFIG_NETFILTER_XT_MATCH_PORTSCAN_MODULE)
+# include <linux/netfilter/xt_portscan.h>
+#else
+# include "xt_portscan.h"
+#endif
+#define PFX KBUILD_MODNAME ": "
+
+enum {
+ TCP_FLAGS_ALL3 = TCP_FLAG_FIN | TCP_FLAG_RST | TCP_FLAG_SYN,
+ TCP_FLAGS_ALL4 = TCP_FLAGS_ALL3 | TCP_FLAG_ACK,
+ TCP_FLAGS_ALL6 = TCP_FLAGS_ALL4 | TCP_FLAG_PSH | TCP_FLAG_URG,
+};
+
+/* Module parameters */
+static unsigned int
+ connmark_mask = ~0,
+ packet_mask = ~0,
+ mark_seen = 0x9,
+ mark_synrcv = 0x1,
+ mark_closed = 0x2,
+ mark_synscan = 0x3,
+ mark_estab1 = 0x4,
+ mark_estab2 = 0x5,
+ mark_cnscan = 0x6,
+ mark_grscan = 0x7,
+ mark_valid = 0x8;
+
+module_param(connmark_mask, uint, S_IRUGO | S_IWUSR);
+module_param(packet_mask, uint, S_IRUGO | S_IWUSR);
+module_param(mark_seen, uint, S_IRUGO | S_IWUSR);
+module_param(mark_synrcv, uint, S_IRUGO | S_IWUSR);
+module_param(mark_closed, uint, S_IRUGO | S_IWUSR);
+module_param(mark_synscan, uint, S_IRUGO | S_IWUSR);
+module_param(mark_estab1, uint, S_IRUGO | S_IWUSR);
+module_param(mark_estab2, uint, S_IRUGO | S_IWUSR);
+module_param(mark_cnscan, uint, S_IRUGO | S_IWUSR);
+module_param(mark_grscan, uint, S_IRUGO | S_IWUSR);
+module_param(mark_valid, uint, S_IRUGO | S_IWUSR);
+MODULE_PARM_DESC(connmark_mask, "only set specified bits in connection mark");
+MODULE_PARM_DESC(packet_mask, "only set specified bits in packet mark");
+MODULE_PARM_DESC(mark_seen, "nfmark value for packet-seen state");
+MODULE_PARM_DESC(mark_synrcv, "connmark value for SYN Received state");
+MODULE_PARM_DESC(mark_closed, "connmark value for closed state");
+MODULE_PARM_DESC(mark_synscan, "connmark value for SYN Scan state");
+MODULE_PARM_DESC(mark_estab1, "connmark value for Established-1 state");
+MODULE_PARM_DESC(mark_estab2, "connmark value for Established-2 state");
+MODULE_PARM_DESC(mark_cnscan, "connmark value for Connect Scan state");
+MODULE_PARM_DESC(mark_grscan, "connmark value for Grab Scan state");
+MODULE_PARM_DESC(mark_valid, "connmark value for Valid state");
+
+/* TCP flag functions */
+static inline bool tflg_ack4(const struct tcphdr *th)
+{
+ return (tcp_flag_word(th) & TCP_FLAGS_ALL4) == TCP_FLAG_ACK;
+}
+
+static inline bool tflg_ack6(const struct tcphdr *th)
+{
+ return (tcp_flag_word(th) & TCP_FLAGS_ALL6) == TCP_FLAG_ACK;
+}
+
+static inline bool tflg_fin(const struct tcphdr *th)
+{
+ return (tcp_flag_word(th) & TCP_FLAGS_ALL3) == TCP_FLAG_FIN;
+}
+
+static inline bool tflg_rst(const struct tcphdr *th)
+{
+ return (tcp_flag_word(th) & TCP_FLAGS_ALL3) == TCP_FLAG_RST;
+}
+
+static inline bool tflg_rstack(const struct tcphdr *th)
+{
+ return (tcp_flag_word(th) & TCP_FLAGS_ALL4) ==
+ (TCP_FLAG_ACK | TCP_FLAG_RST);
+}
+
+static inline bool tflg_syn(const struct tcphdr *th)
+{
+ return (tcp_flag_word(th) & TCP_FLAGS_ALL4) == TCP_FLAG_SYN;
+}
+
+static inline bool tflg_synack(const struct tcphdr *th)
+{
+ return (tcp_flag_word(th) & TCP_FLAGS_ALL4) ==
+ (TCP_FLAG_SYN | TCP_FLAG_ACK);
+}
+
+/* portscan functions */
+static inline bool portscan_mt_stealth(const struct tcphdr *th)
+{
+ /*
+ * "Connection refused" replies to our own probes must not be matched.
+ */
+ if (tflg_rstack(th))
+ return false;
+
+ if (tflg_rst(th) && printk_ratelimit()) {
+ printk(KERN_WARNING PFX "Warning: Pure RST received\n");
+ return false;
+ }
+
+ /*
+ * -p tcp ! --syn -m conntrack --ctstate INVALID: Looking for non-start
+ * packets that are not associated with any connection -- this will
+ * match most scan types (NULL, XMAS, FIN) and ridiculous flag
+ * combinations (SYN-RST, SYN-FIN, SYN-FIN-RST, FIN-RST, etc.).
+ */
+ return !tflg_syn(th);
+}
+
+static inline unsigned int portscan_mt_full(int mark,
+ enum ip_conntrack_info ctstate, bool loopback, const struct tcphdr *tcph,
+ unsigned int payload_len)
+{
+ if (mark == mark_estab2) {
+ /*
+ * -m connmark --mark $ESTAB2
+ */
+ if (tflg_ack4(tcph) && payload_len == 0)
+ return mark; /* keep mark */
+ else if (tflg_rst(tcph) || tflg_fin(tcph))
+ return mark_grscan;
+ else
+ return mark_valid;
+ } else if (mark == mark_estab1) {
+ /*
+ * -m connmark --mark $ESTAB1
+ */
+ if (tflg_rst(tcph) || tflg_fin(tcph))
+ return mark_cnscan;
+ else if (!loopback && tflg_ack4(tcph) && payload_len == 0)
+ return mark_estab2;
+ else
+ return mark_valid;
+ } else if (mark == mark_synrcv) {
+ /*
+ * -m connmark --mark $SYN
+ */
+ if (loopback && tflg_synack(tcph))
+ return mark; /* keep mark */
+ else if (loopback && tflg_rstack(tcph))
+ return mark_closed;
+ else if (tflg_ack6(tcph))
+ return mark_estab1;
+ else
+ return mark_synscan;
+ } else if (ctstate == IP_CT_NEW && tflg_syn(tcph)) {
+ /*
+ * -p tcp --syn --ctstate NEW
+ */
+ return mark_synrcv;
+ }
+ return mark;
+}
+
+static int portscan_mt(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)
+{
+ const struct xt_portscan_match_info *info = matchinfo;
+ enum ip_conntrack_info ctstate;
+ const struct tcphdr *tcph;
+ struct nf_conn *ctdata;
+ struct tcphdr tcph_buf;
+
+ tcph = skb_header_pointer(skb, protoff, sizeof(tcph_buf), &tcph_buf);
+ if (tcph == NULL)
+ return false;
+
+ /* Check for invalid packets: -m conntrack --ctstate INVALID */
+ if ((ctdata = nf_ct_get(skb, &ctstate)) == NULL) {
+ if (info->match_stealth)
+ return portscan_mt_stealth(tcph);
+ /*
+ * If @ctdata is NULL, we cannot match the other scan
+ * types, return.
+ */
+ return false;
+ }
+
+ /*
+ * If -m portscan was previously applied to this packet, the rules we
+ * simulate must not be run through again. And for speedup, do not call
+ * it either when the connection is already VALID.
+ */
+ if ((ctdata->mark & connmark_mask) == mark_valid ||
+ (skb->mark & packet_mask) != mark_seen) {
+ unsigned int n;
+
+ n = portscan_mt_full(ctdata->mark & connmark_mask, ctstate,
+ in == &loopback_dev, tcph,
+ skb->len - protoff - 4 * tcph->doff);
+
+ ctdata->mark = (ctdata->mark & ~connmark_mask) | n;
+ ((struct sk_buff *)skb)->mark =
+ (skb->mark & ~packet_mask) ^ mark_seen;
+ }
+
+ return (info->match_syn && ctdata->mark == mark_synscan) ||
+ (info->match_cn && ctdata->mark == mark_cnscan) ||
+ (info->match_gr && ctdata->mark == mark_grscan);
+}
+
+static int portscan_mt_check(const char *tablename, const void *entry,
+ const struct xt_match *match, void *matchinfo, unsigned int hook_mask)
+{
+ const struct xt_portscan_match_info *info = matchinfo;
+
+ 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 false;
+ }
+ return true;
+}
+
+static struct xt_match portscan_mt_reg __read_mostly = {
+ .name = "portscan",
+ .family = AF_INET,
+ .match = portscan_mt,
+ .checkentry = portscan_mt_check,
+ .matchsize = sizeof(struct xt_portscan_match_info),
+ .proto = IPPROTO_TCP,
+ .me = THIS_MODULE,
+};
+
+static int __init portscan_mt_init(void)
+{
+ return xt_register_match(&portscan_mt_reg);
+}
+
+static void __exit portscan_mt_exit(void)
+{
+ xt_unregister_match(&portscan_mt_reg);
+ return;
+}
+
+module_init(portscan_mt_init);
+module_exit(portscan_mt_exit);
+MODULE_AUTHOR("Jan Engelhardt <jengelh@computergmbh.de>");
+MODULE_DESCRIPTION("netfilter \"portscan\" match");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("ipt_portscan");
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