diff -ruN linux-2.6.19.1.orig/include/linux/netfilter/xt_CHAOS.h linux-2.6.19.1/include/linux/netfilter/xt_CHAOS.h --- linux-2.6.19.1.orig/include/linux/netfilter/xt_CHAOS.h 1970-01-01 01:00:00.000000000 +0100 +++ linux-2.6.19.1/include/linux/netfilter/xt_CHAOS.h 2007-01-11 13:28:07.656144799 +0100 @@ -0,0 +1,14 @@ +#ifndef _LINUX_XT_CHAOS_H +#define _LINUX_XT_CHAOS_H 1 + +enum xt_chaos_variant { + XTCHAOS_NORMAL, + XTCHAOS_TARPIT, + XTCHAOS_DELUDE, +}; + +struct xt_chaos_info { + enum xt_chaos_variant variant; +}; + +#endif /* _LINUX_XT_CHAOS_H */ diff -ruN linux-2.6.19.1.orig/include/linux/netfilter/xt_portscan.h linux-2.6.19.1/include/linux/netfilter/xt_portscan.h --- linux-2.6.19.1.orig/include/linux/netfilter/xt_portscan.h 1970-01-01 01:00:00.000000000 +0100 +++ linux-2.6.19.1/include/linux/netfilter/xt_portscan.h 2007-01-11 13:28:07.656144799 +0100 @@ -0,0 +1,8 @@ +#ifndef _LINUX_XT_PORTSCAN_H +#define _LINUX_XT_PORTSCAN_H 1 + +struct xt_portscan_info { + unsigned int match_stealth, match_syn, match_cn, match_gr; +}; + +#endif /* _LINUX_XT_PORTSCAN_H */ diff -ruN linux-2.6.19.1.orig/net/netfilter/find_match.c linux-2.6.19.1/net/netfilter/find_match.c --- linux-2.6.19.1.orig/net/netfilter/find_match.c 1970-01-01 01:00:00.000000000 +0100 +++ linux-2.6.19.1/net/netfilter/find_match.c 2007-01-11 13:28:12.191994379 +0100 @@ -0,0 +1,37 @@ +/* + xt_request_find_match + by Jan Engelhardt , 2006 - 2007 + + Based upon linux-2.6.18.5/net/netfilter/x_tables.c: + Copyright (C) 2006-2006 Harald Welte + 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 +#include +#include +#include + +/* + * Yeah this code is sub-optimal, but the function is missing in + * mainline so far. -jengelh + */ +static struct xt_match *xt_request_find_match(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; +} diff -ruN linux-2.6.19.1.orig/net/netfilter/Kconfig linux-2.6.19.1/net/netfilter/Kconfig --- linux-2.6.19.1.orig/net/netfilter/Kconfig 2007-01-11 13:27:24.445577700 +0100 +++ linux-2.6.19.1/net/netfilter/Kconfig 2007-01-11 13:28:09.092097179 +0100 @@ -122,6 +122,14 @@ # 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 @@ -148,6 +156,14 @@ . 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 @@ -355,6 +371,14 @@ 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 diff -ruN linux-2.6.19.1.orig/net/netfilter/Makefile linux-2.6.19.1/net/netfilter/Makefile --- linux-2.6.19.1.orig/net/netfilter/Makefile 2007-01-11 13:27:24.445577700 +0100 +++ linux-2.6.19.1/net/netfilter/Makefile 2007-01-11 13:28:07.656144799 +0100 @@ -23,8 +23,10 @@ obj-$(CONFIG_NETFILTER_XTABLES) += x_tables.o xt_tcpudp.o # targets +obj-$(CONFIG_NETFILTER_XT_TARGET_CHAOS) += xt_CHAOS.o obj-$(CONFIG_NETFILTER_XT_TARGET_CLASSIFY) += xt_CLASSIFY.o obj-$(CONFIG_NETFILTER_XT_TARGET_CONNMARK) += xt_CONNMARK.o +obj-$(CONFIG_NETFILTER_XT_TARGET_DELUDE) += xt_DELUDE.o obj-$(CONFIG_NETFILTER_XT_TARGET_DSCP) += xt_DSCP.o obj-$(CONFIG_NETFILTER_XT_TARGET_MARK) += xt_MARK.o obj-$(CONFIG_NETFILTER_XT_TARGET_NFQUEUE) += xt_NFQUEUE.o @@ -47,6 +49,7 @@ obj-$(CONFIG_NETFILTER_XT_MATCH_MARK) += xt_mark.o obj-$(CONFIG_NETFILTER_XT_MATCH_MULTIPORT) += xt_multiport.o obj-$(CONFIG_NETFILTER_XT_MATCH_POLICY) += xt_policy.o +obj-$(CONFIG_NETFILTER_XT_MATCH_PORTSCAN) += xt_portscan.o obj-$(CONFIG_NETFILTER_XT_MATCH_PKTTYPE) += xt_pkttype.o obj-$(CONFIG_NETFILTER_XT_MATCH_QUOTA) += xt_quota.o obj-$(CONFIG_NETFILTER_XT_MATCH_REALM) += xt_realm.o diff -ruN linux-2.6.19.1.orig/net/netfilter/xt_CHAOS.c linux-2.6.19.1/net/netfilter/xt_CHAOS.c --- linux-2.6.19.1.orig/net/netfilter/xt_CHAOS.c 1970-01-01 01:00:00.000000000 +0100 +++ linux-2.6.19.1/net/netfilter/xt_CHAOS.c 2007-01-11 13:28:14.407920893 +0100 @@ -0,0 +1,180 @@ +/* + CHAOS target for netfilter + + Copyright © Jan Engelhardt , 2006 - 2007 + released under the terms of the GNU General Public + License version 2.x and only versions 2.x. +*/ +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include "find_match.c" +#define PFX KBUILD_MODNAME ": " + +/* Out of tree workarounds */ +#include +#if LINUX_VERSION_CODE <= KERNEL_VERSION(2, 6, 18) +# define HAVE_TARGUSERINFO 1 +#endif + +/* 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 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_info *info, + struct sk_buff **pskb, const struct net_device *in, + const struct net_device *out, unsigned int hooknum) +{ + const int protoff = 4 * (*pskb)->nh.iph->ihl; + const int offset = ntohs((*pskb)->nh.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; +#ifdef HAVE_TARGUSERINFO + destiny->target(pskb, in, out, hooknum, destiny, NULL, NULL); +#else + destiny->target(pskb, in, out, hooknum, destiny, NULL); +#endif + return; +} + +static unsigned int xt_chaos_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 +#ifdef HAVE_TARGUSERINFO + , + void *userinfo +#endif + ) +{ + /* Equivalent to: + * -A chaos -m statistic --mode random --probability \ + * $reject_percentage -j REJECT --reject-with host-unreach; + * -A chaos -m statistic --mode random --probability \ + * $delude_percentage -j DELUDE; + * -A chaos -j DROP; + */ + const struct xt_chaos_info *info = targinfo; + + if((unsigned int)net_random() <= reject_percentage) +#ifdef HAVE_TARGUSERINFO + return xt_reject->target(pskb, in, out, hooknum, target, + &reject_params, userinfo); +#else + return xt_reject->target(pskb, in, out, hooknum, target, + &reject_params); +#endif + + /* TARPIT/DELUDE may not be called from the OUTPUT chain */ + if((*pskb)->nh.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 struct xt_target xt_chaos_info = { + .name = "CHAOS", + .target = xt_chaos_target, + .table = "filter", + .targetsize = sizeof(struct xt_chaos_info), + .hooks = (1 << NF_IP_LOCAL_IN) | (1 << NF_IP_FORWARD) | + (1 << NF_IP_LOCAL_OUT), + .family = AF_INET, + .me = THIS_MODULE, +}; + +static int __init xt_chaos_init(void) +{ + int ret = -EINVAL; + + xm_tcp = xt_request_find_match(AF_INET, "tcp", 0); + if(xm_tcp == NULL) { + printk(KERN_WARNING PFX "Could not find \"tcp\" match\n"); + return -EINVAL; + } + + xt_reject = xt_request_find_target(AF_INET, "REJECT", 0); + if(xt_reject == NULL) { + printk(KERN_WARNING PFX "Could not find \"REJECT\" target\n"); + goto out2; + } + + xt_tarpit = xt_request_find_target(AF_INET, "TARPIT", 0); + if(xt_tarpit == NULL) { + printk(KERN_WARNING PFX "Could not find \"TARPIT\" target\n"); + goto out3; + } + + xt_delude = xt_request_find_target(AF_INET, "DELUDE", 0); + if(xt_delude == NULL) { + printk(KERN_WARNING PFX "Could not find \"DELUDE\" target\n"); + goto out4; + } + + if((ret = xt_register_target(&xt_chaos_info)) != 0) { + printk(KERN_WARNING PFX "xt_register_target returned " + "error %d\n", ret); + goto out5; + } + + return 0; + + out5: + module_put(xt_delude->me); + out4: + module_put(xt_tarpit->me); + out3: + module_put(xt_reject->me); + out2: + module_put(xm_tcp->me); + return ret; +} + +static void __exit xt_chaos_exit(void) +{ + xt_unregister_target(&xt_chaos_info); + module_put(xm_tcp->me); + module_put(xt_reject->me); + module_put(xt_delude->me); + module_put(xt_tarpit->me); + return; +} + +module_init(xt_chaos_init); +module_exit(xt_chaos_exit); +MODULE_AUTHOR("Jan Engelhardt "); +MODULE_DESCRIPTION("netfilter CHAOS target"); +MODULE_LICENSE("GPL"); +MODULE_ALIAS("ipt_CHAOS"); diff -ruN linux-2.6.19.1.orig/net/netfilter/xt_DELUDE.c linux-2.6.19.1/net/netfilter/xt_DELUDE.c --- linux-2.6.19.1.orig/net/netfilter/xt_DELUDE.c 1970-01-01 01:00:00.000000000 +0100 +++ linux-2.6.19.1/net/netfilter/xt_DELUDE.c 2007-01-11 13:28:07.656144799 +0100 @@ -0,0 +1,265 @@ +/* + DELUDE target + Copyright © Jan Engelhardt , 2007 + + 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 + + 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 +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#ifdef CONFIG_BRIDGE_NETFILTER +#include +#endif +#define PFX KBUILD_MODNAME ": " + +/* Out of tree workarounds */ +#include +#if LINUX_VERSION_CODE <= KERNEL_VERSION(2, 6, 18) +# define HAVE_TARGINFOSIZE 1 +# define HAVE_TARGUSERINFO 1 +#endif +#if LINUX_VERSION_CODE >= KERNEL_VERSION(2, 6, 20) +# define nfmark mark +#endif + +static inline struct rtable *route_reverse(struct sk_buff *skb, + struct tcphdr *tcph, int hook) +{ + struct iphdr *iph = skb->nh.iph; + struct dst_entry *odst; + struct flowi fl = {}; + struct rtable *rt; + + /* We don't require ip forwarding to be enabled to be able to + * send a RST reply for bridged traffic. */ + if (hook != NF_IP_FORWARD +#ifdef CONFIG_BRIDGE_NETFILTER + || (skb->nf_bridge && skb->nf_bridge->mask & BRNF_BRIDGED) +#endif + ) { + fl.nl_u.ip4_u.daddr = iph->saddr; + if (hook == NF_IP_LOCAL_IN) + fl.nl_u.ip4_u.saddr = iph->daddr; + fl.nl_u.ip4_u.tos = RT_TOS(iph->tos); + + if (ip_route_output_key(&rt, &fl) != 0) + return NULL; + } else { + /* non-local src, find valid iif to satisfy + * rp-filter when calling ip_route_input. */ + fl.nl_u.ip4_u.daddr = iph->daddr; + if (ip_route_output_key(&rt, &fl) != 0) + return NULL; + + odst = skb->dst; + if (ip_route_input(skb, iph->saddr, iph->daddr, + RT_TOS(iph->tos), rt->u.dst.dev) != 0) { + dst_release(&rt->u.dst); + return NULL; + } + dst_release(&rt->u.dst); + rt = (struct rtable *)skb->dst; + skb->dst = odst; + + fl.nl_u.ip4_u.daddr = iph->saddr; + fl.nl_u.ip4_u.saddr = iph->daddr; + fl.nl_u.ip4_u.tos = RT_TOS(iph->tos); + } + + if (rt->u.dst.error) { + dst_release(&rt->u.dst); + return NULL; + } + + fl.proto = IPPROTO_TCP; + fl.fl_ip_sport = tcph->dest; + fl.fl_ip_dport = tcph->source; + + xfrm_lookup((struct dst_entry **)&rt, &fl, NULL, 0); + + return rt; +} + +static void send_reset(struct sk_buff *oldskb, int hook) +{ + struct sk_buff *nskb; + struct iphdr *iph = oldskb->nh.iph; + struct tcphdr _otcph, *oth, *tcph; + struct rtable *rt; + u_int16_t tmp_port; + u_int32_t tmp_addr; + int hh_len; + + /* IP header checks: fragment. */ + if (oldskb->nh.iph->frag_off & htons(IP_OFFSET)) + return; + + oth = skb_header_pointer(oldskb, oldskb->nh.iph->ihl * 4, + sizeof(_otcph), &_otcph); + if (oth == NULL) + return; + + /* DELUDE only answers SYN. */ + if(!oth->syn || oth->ack || oth->fin || oth->rst) + return; + + /* Check checksum */ + if (nf_ip_checksum(oldskb, hook, iph->ihl * 4, IPPROTO_TCP)) + return; + + if ((rt = route_reverse(oldskb, oth, hook)) == NULL) + return; + + hh_len = LL_RESERVED_SPACE(rt->u.dst.dev); + + /* 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, hh_len, skb_tailroom(oldskb), + GFP_ATOMIC); + if (!nskb) { + dst_release(&rt->u.dst); + return; + } + + dst_release(nskb->dst); + nskb->dst = &rt->u.dst; + + /* This packet will not be the same as the other: clear nf fields */ + nf_reset(nskb); + nskb->nfmark = 0; + skb_init_secmark(nskb); + + tcph = (struct tcphdr *)((u_int32_t*)nskb->nh.iph + nskb->nh.iph->ihl); + + /* Swap source and dest */ + tmp_addr = nskb->nh.iph->saddr; + nskb->nh.iph->saddr = nskb->nh.iph->daddr; + nskb->nh.iph->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, nskb->nh.iph->ihl*4 + sizeof(struct tcphdr)); + nskb->nh.iph->tot_len = htons(nskb->len); + + tcph->seq = oth->ack_seq; + tcph->ack_seq = 0; + + /* Reset flags */ + ((u_int8_t *)tcph)[13] = 0; + tcph->syn = tcph->ack = 1; + + tcph->window = 0; + tcph->urg_ptr = 0; + + /* Adjust TCP checksum */ + tcph->check = 0; + tcph->check = tcp_v4_check(tcph, sizeof(struct tcphdr), + nskb->nh.iph->saddr, + nskb->nh.iph->daddr, + csum_partial((char *)tcph, + sizeof(struct tcphdr), 0)); + + /* Adjust IP TTL, DF */ + nskb->nh.iph->ttl = dst_metric(nskb->dst, RTAX_HOPLIMIT); + /* Set DF, id = 0 */ + nskb->nh.iph->frag_off = htons(IP_DF); + nskb->nh.iph->id = 0; + + /* Adjust IP checksum */ + nskb->nh.iph->check = 0; + nskb->nh.iph->check = ip_fast_csum((unsigned char *)nskb->nh.iph, + nskb->nh.iph->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); + return; +} + +static unsigned int xt_delude_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 +#ifdef HAVE_TARGUSERINFO + , + void *userinfo +#endif + ) +{ + /* WARNING: This code causes reentry within iptables. + This means that the iptables jump stack is now crap. We + must return an absolute verdict. --RR */ + send_reset(*pskb, hooknum); + return NF_DROP; +} + +static int xt_delude_check(const char *tablename, const void *e_void, + const struct xt_target *target, void *targinfo, +#ifdef HAVE_TARGINFOSIZE + unsigned int targinfosize, +#endif + unsigned int hook_mask) +{ + 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 1; +} + +static struct xt_target xt_delude_info = { + .name = "DELUDE", + .target = xt_delude_target, + .checkentry = xt_delude_check, + .table = "filter", + .hooks = (1 << NF_IP_LOCAL_IN) | (1 << NF_IP_FORWARD) | + (1 << NF_IP_LOCAL_OUT), + .proto = IPPROTO_TCP, + .family = AF_INET, + .me = THIS_MODULE, +}; + +static int __init xt_delude_init(void) +{ + return xt_register_target(&xt_delude_info); +} + +static void __exit xt_delude_exit(void) +{ + xt_unregister_target(&xt_delude_info); +} + +module_init(xt_delude_init); +module_exit(xt_delude_exit); +MODULE_LICENSE("GPL"); +MODULE_AUTHOR("Jan Engelhardt "); +MODULE_DESCRIPTION("netfilter DELUDE target"); diff -ruN linux-2.6.19.1.orig/net/netfilter/xt_portscan.c linux-2.6.19.1/net/netfilter/xt_portscan.c --- linux-2.6.19.1.orig/net/netfilter/xt_portscan.c 1970-01-01 01:00:00.000000000 +0100 +++ linux-2.6.19.1/net/netfilter/xt_portscan.c 2007-01-11 13:28:14.407920893 +0100 @@ -0,0 +1,282 @@ +/* + portscan match for netfilter + + Written by Jan Engelhardt, 2006 - 2007 + released under the terms of the GNU General Public + License version 2.x and only versions 2.x. +*/ +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#if defined(CONFIG_IP_NF_CONNTRACK) || defined(CONFIG_IP_NF_CONNTRACK_MODULE) +# include +#else /* linux-2.6.20+ */ +# include +#endif +#include +#define PFX KBUILD_MODNAME ": " + +/* Out of tree workarounds */ +#if LINUX_VERSION_CODE <= KERNEL_VERSION(2, 6, 18) +# define HAVE_MATCHINFOSIZE 1 +#endif +#if LINUX_VERSION_CODE >= KERNEL_VERSION(2, 6, 20) +# define nfmark mark +#endif + +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 int tflg_ack4(const struct tcphdr *th) +{ + return (tcp_flag_word(th) & TCP_FLAGS_ALL4) == TCP_FLAG_ACK; +} + +static inline int tflg_ack6(const struct tcphdr *th) +{ + return (tcp_flag_word(th) & TCP_FLAGS_ALL6) == TCP_FLAG_ACK; +} + +static inline int tflg_fin(const struct tcphdr *th) +{ + return (tcp_flag_word(th) & TCP_FLAGS_ALL3) == TCP_FLAG_FIN; +} + +static inline int tflg_rst(const struct tcphdr *th) +{ + return (tcp_flag_word(th) & TCP_FLAGS_ALL3) == TCP_FLAG_RST; +} + +static inline int tflg_rstack(const struct tcphdr *th) +{ + return (tcp_flag_word(th) & TCP_FLAGS_ALL4) == + (TCP_FLAG_ACK | TCP_FLAG_RST); +} + +static inline int tflg_syn(const struct tcphdr *th) +{ + return (tcp_flag_word(th) & TCP_FLAGS_ALL4) == TCP_FLAG_SYN; +} + +static inline int tflg_synack(const struct tcphdr *th) +{ + return (tcp_flag_word(th) & TCP_FLAGS_ALL4) == + (TCP_FLAG_SYN | TCP_FLAG_ACK); +} + +/* portscan functions */ +static inline int xt_portscan_stealth(const struct tcphdr *th) +{ + /* + * "Connection refused" replies to our own probes must not be matched. + */ + if(tflg_rstack(th)) + return 0; + + if(tflg_rst(th) && printk_ratelimit()) { + printk(KERN_WARNING PFX "Warning: Pure RST received\n"); + return 0; + } + + /* + * -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 int xt_portscan_full(int mark, enum ip_conntrack_info ctstate, + int loopback, const struct tcphdr *tcph, 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 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) +{ + const struct xt_portscan_info *info = matchinfo; + enum ip_conntrack_info ctstate; + struct ip_conntrack *ctdata; + const struct tcphdr *tcph; + struct tcphdr tcph_buf; + + tcph = skb_header_pointer(skb, protoff, sizeof(tcph_buf), &tcph_buf); + if(tcph == NULL) + return 0; + + /* Check for invalid packets: -m conntrack --ctstate INVALID */ + if((ctdata = ip_conntrack_get(skb, &ctstate)) == NULL) { + if(info->match_stealth) + return xt_portscan_stealth(tcph); + /* + * If @ctdata is NULL, we cannot match the other scan + * types, return. + */ + return 0; + } + + /* + * 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->nfmark & packet_mask) != mark_seen) + { + unsigned int n; + n = xt_portscan_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)->nfmark = + (skb->nfmark & ~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 xt_portscan_checkentry(const char *tablename, const void *entry, + const struct xt_match *match, void *matchinfo, +#ifdef HAVE_MATCHINFOSIZE + unsigned int matchinfosize, +#endif + unsigned int hook_mask) +{ + const struct xt_portscan_info *info = matchinfo; +#ifdef HAVE_MATCHINFOSIZE + if(matchinfosize != XT_ALIGN(sizeof(struct xt_portscan_info))) { + printk(KERN_WARNING PFX "matchinfosize %u != %Zu\n", + matchinfosize, + XT_ALIGN(sizeof(struct xt_portscan_info))); + return 0; + } +#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 1; +} + +static struct xt_match xt_portscan = { + .name = "portscan", + .match = xt_portscan_match, + .checkentry = xt_portscan_checkentry, + .matchsize = sizeof(struct xt_portscan_info), + .proto = IPPROTO_TCP, + .family = AF_INET, + .me = THIS_MODULE, +}; + +static int __init xt_portscan_init(void) +{ + return xt_register_match(&xt_portscan); +} + +static void __exit xt_portscan_exit(void) +{ + xt_unregister_match(&xt_portscan); + return; +} + +module_init(xt_portscan_init); +module_exit(xt_portscan_exit); +MODULE_AUTHOR("Jan Engelhardt "); +MODULE_DESCRIPTION("netfilter portscan match module"); +MODULE_LICENSE("GPL"); +MODULE_ALIAS("ipt_portscan");