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[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
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@ -179,7 +179,7 @@ Index: linux-2.6.23/net/netfilter/xt_CHAOS.c
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===================================================================
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--- /dev/null 1970-01-01 00:00:00.000000000 +0000
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+++ linux-2.6.23/net/netfilter/xt_CHAOS.c 2007-10-10 13:52:59.000000000 +0800
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@@ -0,0 +1,204 @@
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@@ -0,0 +1,205 @@
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+/*
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+ CHAOS target for netfilter
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+
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@ -233,7 +233,8 @@ Index: linux-2.6.23/net/netfilter/xt_CHAOS.c
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+ const int protoff = ip_hdrlen(*pskb);
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+ const int offset = ntohs(ip_hdr(*pskb)->frag_off) & IP_OFFSET;
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+ const struct xt_target *destiny;
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+ int hotdrop = 0, ret;
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+ bool hotdrop = false;
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+ int ret;
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+
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+ ret = xm_tcp->match(*pskb, in, out, xm_tcp, &tcp_params,
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+ offset, protoff, &hotdrop);
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@ -284,7 +285,7 @@ Index: linux-2.6.23/net/netfilter/xt_CHAOS.c
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+ return NF_DROP;
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+}
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+
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+static int xt_chaos_checkentry(const char *tablename, const void *entry,
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+static bool xt_chaos_checkentry(const char *tablename, const void *entry,
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+ const struct xt_target *target, void *targinfo,
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+#ifdef HAVE_TARGINFOSIZE
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+ unsigned int targinfosize,
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@ -295,14 +296,14 @@ Index: linux-2.6.23/net/netfilter/xt_CHAOS.c
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+ if(info->variant == XTCHAOS_DELUDE && !have_delude) {
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+ printk(KERN_WARNING PFX "Error: Cannot use --delude when "
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+ "DELUDE module not available\n");
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+ return 0;
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+ return false;
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+ }
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+ if(info->variant == XTCHAOS_TARPIT && !have_tarpit) {
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+ printk(KERN_WARNING PFX "Error: Cannot use --tarpit when "
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+ "TARPIT module not available\n");
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+ return 0;
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+ return false;
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+ }
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+ return 1;
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+ return true;
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+}
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+
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+static struct xt_target xt_chaos_info = {
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@ -634,7 +635,7 @@ Index: linux-2.6.23/net/netfilter/xt_DELUDE.c
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+ return NF_DROP;
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+}
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+
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+static int xt_delude_check(const char *tablename, const void *e_void,
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+static bool xt_delude_check(const char *tablename, const void *e_void,
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+ const struct xt_target *target, void *targinfo,
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+#ifdef HAVE_TARGINFOSIZE
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+ unsigned int targinfosize,
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@ -644,9 +645,9 @@ Index: linux-2.6.23/net/netfilter/xt_DELUDE.c
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+ if(hook_mask & ~((1 << NF_IP_LOCAL_IN) | (1 << NF_IP_FORWARD))) {
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+ printk(KERN_WARNING PFX "DELUDE may not be used in chains "
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+ "other than INPUT and FORWARD\n");
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+ return 0;
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+ return false;
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+ }
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+ return 1;
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+ return true;
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+}
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+
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+static struct xt_target xt_delude_info = {
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@ -854,10 +855,10 @@ Index: linux-2.6.23/net/netfilter/xt_portscan.c
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+ return mark;
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+}
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+
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+static int xt_portscan_match(const struct sk_buff *skb,
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+static bool xt_portscan_match(const struct sk_buff *skb,
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+ const struct net_device *in, const struct net_device *out,
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+ const struct xt_match *match, const void *matchinfo, int offset,
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+ unsigned int protoff, int *hotdrop)
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+ unsigned int protoff, bool *hotdrop)
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+{
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+ const struct xt_portscan_info *info = matchinfo;
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+ enum ip_conntrack_info ctstate;
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@ -867,7 +868,7 @@ Index: linux-2.6.23/net/netfilter/xt_portscan.c
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+
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+ tcph = skb_header_pointer(skb, protoff, sizeof(tcph_buf), &tcph_buf);
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+ if(tcph == NULL)
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+ return 0;
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+ return false;
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+
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+ /* Check for invalid packets: -m conntrack --ctstate INVALID */
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+ if((ctdata = nf_ct_get(skb, &ctstate)) == NULL) {
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@ -877,7 +878,7 @@ Index: linux-2.6.23/net/netfilter/xt_portscan.c
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+ * If @ctdata is NULL, we cannot match the other scan
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+ * types, return.
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+ */
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+ return 0;
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+ return false;
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+ }
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+
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+ /*
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@ -903,7 +904,7 @@ Index: linux-2.6.23/net/netfilter/xt_portscan.c
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+ (info->match_gr && ctdata->mark == mark_grscan);
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+}
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+
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+static int xt_portscan_checkentry(const char *tablename, const void *entry,
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+static bool xt_portscan_checkentry(const char *tablename, const void *entry,
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+ const struct xt_match *match, void *matchinfo,
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+#ifdef HAVE_MATCHINFOSIZE
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+ unsigned int matchinfosize,
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@ -916,15 +917,15 @@ Index: linux-2.6.23/net/netfilter/xt_portscan.c
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+ printk(KERN_WARNING PFX "matchinfosize %u != %Zu\n",
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+ matchinfosize,
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+ XT_ALIGN(sizeof(struct xt_portscan_info)));
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+ return 0;
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+ return false;
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+ }
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+#endif
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+ if((info->match_stealth & ~1) || (info->match_syn & ~1) ||
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+ (info->match_cn & ~1) || (info->match_gr & ~1)) {
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+ printk(KERN_WARNING PFX "Invalid flags\n");
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+ return 0;
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+ return false;
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+ }
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+ return 1;
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+ return true;
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+}
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+
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+static struct xt_match xt_portscan = {
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@ -0,0 +1,325 @@
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Index: linux-2.6.23/net/netfilter/Kconfig
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===================================================================
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--- linux-2.6.23.orig/net/netfilter/Kconfig
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+++ linux-2.6.23/net/netfilter/Kconfig
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@@ -401,6 +401,23 @@ config NETFILTER_XT_TARGET_CONNSECMARK
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To compile it as a module, choose M here. If unsure, say N.
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+config NETFILTER_XT_TARGET_TARPIT
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+ tristate '"TARPIT" target support'
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+ depends on NETFILTER_XTABLES
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+ ---help---
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+ Adds a TARPIT target to iptables, which captures and holds
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+ incoming TCP connections using no local per-connection resources.
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+ Connections are accepted, but immediately switched to the persist
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+ state (0 byte window), in which the remote side stops sending data
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+ and asks to continue every 60-240 seconds. Attempts to close the
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+ connection are ignored, forcing the remote side to time out the
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+ connection in 12-24 minutes.
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+
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+ This offers similar functionality to LaBrea
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+ <http://www.hackbusters.net/LaBrea/>, but does not require dedicated
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+ hardware or IPs. Any TCP port that you would normally DROP or REJECT
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+ can instead become a tarpit.
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+
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config NETFILTER_XT_TARGET_TCPMSS
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tristate '"TCPMSS" target support'
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depends on NETFILTER_XTABLES && (IPV6 || IPV6=n)
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Index: linux-2.6.23/net/netfilter/Makefile
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===================================================================
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--- linux-2.6.23.orig/net/netfilter/Makefile
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+++ linux-2.6.23/net/netfilter/Makefile
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@@ -49,6 +49,7 @@ obj-$(CONFIG_NETFILTER_XT_TARGET_NFLOG)
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obj-$(CONFIG_NETFILTER_XT_TARGET_NOTRACK) += xt_NOTRACK.o
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obj-$(CONFIG_NETFILTER_XT_TARGET_TRACE) += xt_TRACE.o
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obj-$(CONFIG_NETFILTER_XT_TARGET_SECMARK) += xt_SECMARK.o
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+obj-$(CONFIG_NETFILTER_XT_TARGET_TARPIT) += xt_TARPIT.o
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obj-$(CONFIG_NETFILTER_XT_TARGET_TCPMSS) += xt_TCPMSS.o
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obj-$(CONFIG_NETFILTER_XT_TARGET_CONNSECMARK) += xt_CONNSECMARK.o
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Index: linux-2.6.23/net/netfilter/xt_TARPIT.c
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===================================================================
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--- /dev/null
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+++ linux-2.6.23/net/netfilter/xt_TARPIT.c
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@@ -0,0 +1,280 @@
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+/*
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+ * Kernel module to capture and hold incoming TCP connections using
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+ * no local per-connection resources.
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+ *
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+ * Based on ipt_REJECT.c and offering functionality similar to
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+ * LaBrea <http://www.hackbusters.net/LaBrea/>.
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+ *
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+ * Copyright (c) 2002 Aaron Hopkins <tools@die.net>
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+ *
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+ * This program is free software; you can redistribute it and/or modify
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+ * it under the terms of the GNU General Public License as published by
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+ * the Free Software Foundation; either version 2 of the License, or
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+ * (at your option) any later version.
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+ *
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+ * This program is distributed in the hope that it will be useful,
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+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
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+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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+ * GNU General Public License for more details.
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+ *
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+ * You should have received a copy of the GNU General Public License
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+ * along with this program; if not, write to the Free Software
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+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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+ *
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+ * Goal:
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+ * - Allow incoming TCP connections to be established.
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+ * - Passing data should result in the connection being switched to the
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+ * persist state (0 byte window), in which the remote side stops sending
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+ * data and asks to continue every 60 seconds.
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+ * - Attempts to shut down the connection should be ignored completely, so
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+ * the remote side ends up having to time it out.
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+ *
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+ * This means:
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+ * - Reply to TCP SYN,!ACK,!RST,!FIN with SYN-ACK, window 5 bytes
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+ * - Reply to TCP SYN,ACK,!RST,!FIN with RST to prevent spoofing
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+ * - Reply to TCP !SYN,!RST,!FIN with ACK, window 0 bytes, rate-limited
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+ */
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+
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+#include <linux/version.h>
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+#include <linux/module.h>
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+#include <linux/skbuff.h>
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+#include <linux/ip.h>
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+#include <net/ip.h>
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+#include <net/tcp.h>
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+#include <net/icmp.h>
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+struct in_device;
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+#include <net/route.h>
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+#include <linux/random.h>
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+#include <linux/netfilter_ipv4/ip_tables.h>
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+
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+#if 0
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+#define DEBUGP printk
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+#else
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+#define DEBUGP(format, args...)
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+#endif
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+
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+/* Stolen from ip_finish_output2 */
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+static int ip_direct_send(struct sk_buff *skb)
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+{
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+ struct dst_entry *dst = skb->dst;
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+
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+ if (dst->hh != NULL)
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+ return neigh_hh_output(dst->hh, skb);
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+ else if (dst->neighbour != NULL)
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+ return dst->neighbour->output(skb);
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+
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+ if (net_ratelimit())
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+ printk(KERN_DEBUG "TARPIT ip_direct_send: no header cache and no neighbor!\n");
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+
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+ kfree_skb(skb);
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+ return -EINVAL;
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+}
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+
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+
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+/* Send reply */
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+static void tarpit_tcp(const struct sk_buff *oskb, struct rtable *ort,
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+ unsigned int local)
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+{
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+ struct sk_buff *nskb;
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+ struct rtable *nrt;
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+ struct tcphdr *otcph, *ntcph;
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+ struct flowi fl = {};
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+ unsigned int otcplen;
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+ u_int16_t tmp;
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+
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+ const struct iphdr *oiph = ip_hdr(oskb);
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+ struct iphdr *niph;
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+
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+ /* A truncated TCP header is not going to be useful */
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+ if (oskb->len < ip_hdrlen(oskb) + sizeof(struct tcphdr))
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+ return;
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+
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+ otcph = (void *)oiph + ip_hdrlen(oskb);
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+ otcplen = oskb->len - ip_hdrlen(oskb);
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+
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+ /* No replies for RST or FIN */
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+ if (otcph->rst || otcph->fin)
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+ return;
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+
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+ /* No reply to !SYN,!ACK. Rate-limit replies to !SYN,ACKs */
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+ if (!otcph->syn && (!otcph->ack || !xrlim_allow(&ort->u.dst, 1*HZ)))
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+ return;
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+
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+ /* Check checksum. */
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+ if (tcp_v4_check(otcplen, oiph->saddr, oiph->daddr,
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+ csum_partial((char *)otcph, otcplen, 0)) != 0)
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+ return;
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+
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+ /*
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+ * Copy skb (even if skb is about to be dropped, we cannot just
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+ * clone it because there may be other things, such as tcpdump,
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+ * interested in it)
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+ */
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+ nskb = skb_copy(oskb, GFP_ATOMIC);
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+ if (nskb == NULL)
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+ return;
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+
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+ niph = ip_hdr(nskb);
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+
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+ /* This packet will not be the same as the other: clear nf fields */
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+ nf_conntrack_put(nskb->nfct);
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+ nskb->nfct = NULL;
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+#ifdef CONFIG_NETFILTER_DEBUG
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+ nskb->nf_debug = 0;
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+#endif
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+
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+ ntcph = (void *)niph + ip_hdrlen(nskb);
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+
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+ /* Truncate to length (no data) */
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+ ntcph->doff = sizeof(struct tcphdr)/4;
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+ skb_trim(nskb, ip_hdrlen(nskb) + sizeof(struct tcphdr));
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+ niph->tot_len = htons(nskb->len);
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+
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+ /* Swap source and dest */
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+ niph->daddr = xchg(&niph->saddr, niph->daddr);
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+ tmp = ntcph->source;
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+ ntcph->source = ntcph->dest;
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+ ntcph->dest = tmp;
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+
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+ /* Use supplied sequence number or make a new one */
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+ ntcph->seq = otcph->ack ? otcph->ack_seq
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+ : htonl(secure_tcp_sequence_number(niph->saddr,
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+ niph->daddr,
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+ ntcph->source,
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+ ntcph->dest));
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+
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+ /* Our SYN-ACKs must have a >0 window */
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+ ntcph->window = (otcph->syn && !otcph->ack) ? htons(5) : 0;
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+
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+ ntcph->urg_ptr = 0;
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+
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+ /* Reset flags */
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+ ((u_int8_t *)ntcph)[13] = 0;
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+
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+ if (otcph->syn && otcph->ack) {
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+ ntcph->rst = 1;
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+ ntcph->ack_seq = 0;
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+ } else {
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+ ntcph->syn = otcph->syn;
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+ ntcph->ack = 1;
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+ ntcph->ack_seq = htonl(ntohl(otcph->seq) + otcph->syn);
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+ }
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+
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+ /* Adjust TCP checksum */
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+ ntcph->check = 0;
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+ ntcph->check = tcp_v4_check(sizeof(struct tcphdr),
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+ niph->saddr,
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+ niph->daddr,
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+ csum_partial((char *)ntcph,
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+ sizeof(struct tcphdr), 0));
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+
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+ fl.nl_u.ip4_u.daddr = niph->daddr;
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+ fl.nl_u.ip4_u.saddr = local ? niph->saddr : 0;
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+ fl.nl_u.ip4_u.tos = RT_TOS(niph->tos) | RTO_CONN;
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+ fl.oif = 0;
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+
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+ if (ip_route_output_key(&nrt, &fl))
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+ goto free_nskb;
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+
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+ dst_release(nskb->dst);
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+ nskb->dst = &nrt->u.dst;
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+
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+ /* Adjust IP TTL */
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+ niph->ttl = dst_metric(nskb->dst, RTAX_HOPLIMIT);
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+
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+ /* Set DF, id = 0 */
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+ niph->frag_off = htons(IP_DF);
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+ niph->id = 0;
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+
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+ /* Adjust IP checksum */
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+ niph->check = 0;
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+ niph->check = ip_fast_csum((unsigned char *)niph, niph->ihl);
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+
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+ /* "Never happens" */
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+ if (nskb->len > dst_mtu(nskb->dst))
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+ goto free_nskb;
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+
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+ ip_direct_send(nskb);
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+ return;
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+
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+ free_nskb:
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+ kfree_skb(nskb);
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+}
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+
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+static unsigned int xt_tarpit_target(struct sk_buff **pskb,
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+ const struct net_device *in,
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+ const struct net_device *out,
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+ unsigned int hooknum,
|
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+ const struct xt_target *target,
|
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+ const void *targinfo)
|
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+{
|
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+ const struct sk_buff *skb = *pskb;
|
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+ const struct iphdr *iph = ip_hdr(skb);
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+ struct rtable *rt = (void *)skb->dst;
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+
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+ /* Do we have an input route cache entry? */
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+ if (rt == NULL)
|
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+ return NF_DROP;
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+
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+ /* No replies to physical multicast/broadcast */
|
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+ if (skb->pkt_type != PACKET_HOST && skb->pkt_type != PACKET_OTHERHOST)
|
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+ return NF_DROP;
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+
|
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+ /* Now check at the protocol level */
|
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+ if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST))
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+ return NF_DROP;
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+
|
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+ /*
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+ * Our naive response construction does not deal with IP
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+ * options, and probably should not try.
|
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+ */
|
||||
+ 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");
|
Loading…
Reference in New Issue
Block a user