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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

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SVN-Revision: 9255
This commit is contained in:
Gabor Juhos 2007-10-11 07:08:40 +00:00
parent 4f430b08cc
commit b52069462e
2 changed files with 343 additions and 17 deletions
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35
target/linux/generic-2.6/patches-2.6.23/170-netfilter_chaostables.patch
View File

@ -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 = {

325
target/linux/generic-2.6/patches-2.6.23/171-netfilter_tarpit.patch Normal file
View File

@ -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");