From 55b47c7a3f7ab6a9d0430c6b753ccf3cc3cac7b8 Mon Sep 17 00:00:00 2001
From: Hans Schillstrom <hans.schillstrom@ericsson.com>
Date: Wed, 2 May 2012 18:59:28 +0200
Subject: [PATCH 1/1] netfilter: add xt_hmark target for hash-based skb marking
The target allows you to create rules in the "raw" and "mangle" tables
which set the skbuff mark by means of hash calculation within a given
range. The nfmark can influence the routing method (see "Use netfilter
MARK value as routing key") and can also be used by other subsystems to
change their behaviour.
Some examples:
* Default rule handles all TCP, UDP, SCTP, ESP & AH
iptables -t mangle -A PREROUTING -m state --state NEW,ESTABLISHED,RELATED \
-j HMARK --hmark-offset 10000 --hmark-mod 10
* Handle SCTP and hash dest port only and produce a nfmark between 100-119.
iptables -t mangle -A PREROUTING -p SCTP -j HMARK --src-mask 0 --dst-mask 0 \
--sp-mask 0 --offset 100 --mod 20
* Fragment safe Layer 3 only, that keep a class C network flow together
iptables -t mangle -A PREROUTING -j HMARK --method L3 \
--src-mask 24 --mod 20 --offset 100
[ A big part of this patch has been refactorized by Pablo Neira Ayuso ]
Signed-off-by: Hans Schillstrom <hans.schillstrom@ericsson.com>
---
include/linux/netfilter/xt_HMARK.h | 62 ++++++
net/netfilter/Kconfig | 15 ++
net/netfilter/Makefile | 1 +
net/netfilter/xt_HMARK.c | 371 ++++++++++++++++++++++++++++++++++++
4 files changed, 449 insertions(+), 0 deletions(-)
create mode 100644 include/linux/netfilter/xt_HMARK.h
create mode 100644 net/netfilter/xt_HMARK.c
new file mode 100644
@@ -0,0 +1,62 @@
+#ifndef XT_HMARK_H_
+#define XT_HMARK_H_
+
+#include <linux/types.h>
+
+enum {
+ XT_HMARK_NONE,
+ XT_HMARK_SADR_AND,
+ XT_HMARK_DADR_AND,
+ XT_HMARK_SPI_AND,
+ XT_HMARK_SPI_OR,
+ XT_HMARK_SPORT_AND,
+ XT_HMARK_DPORT_AND,
+ XT_HMARK_SPORT_OR,
+ XT_HMARK_DPORT_OR,
+ XT_HMARK_PROTO_AND,
+ XT_HMARK_RND,
+ XT_HMARK_MODULUS,
+ XT_HMARK_OFFSET,
+ XT_HMARK_CT,
+ XT_HMARK_METHOD_L3,
+ XT_HMARK_METHOD_L3_4,
+ XT_F_HMARK_SADR_AND = 1 << XT_HMARK_SADR_AND,
+ XT_F_HMARK_DADR_AND = 1 << XT_HMARK_DADR_AND,
+ XT_F_HMARK_SPI_AND = 1 << XT_HMARK_SPI_AND,
+ XT_F_HMARK_SPI_OR = 1 << XT_HMARK_SPI_OR,
+ XT_F_HMARK_SPORT_AND = 1 << XT_HMARK_SPORT_AND,
+ XT_F_HMARK_DPORT_AND = 1 << XT_HMARK_DPORT_AND,
+ XT_F_HMARK_SPORT_OR = 1 << XT_HMARK_SPORT_OR,
+ XT_F_HMARK_DPORT_OR = 1 << XT_HMARK_DPORT_OR,
+ XT_F_HMARK_PROTO_AND = 1 << XT_HMARK_PROTO_AND,
+ XT_F_HMARK_RND = 1 << XT_HMARK_RND,
+ XT_F_HMARK_MODULUS = 1 << XT_HMARK_MODULUS,
+ XT_F_HMARK_OFFSET = 1 << XT_HMARK_OFFSET,
+ XT_F_HMARK_CT = 1 << XT_HMARK_CT,
+ XT_F_HMARK_METHOD_L3 = 1 << XT_HMARK_METHOD_L3,
+ XT_F_HMARK_METHOD_L3_4 = 1 << XT_HMARK_METHOD_L3_4,
+};
+
+union hmark_ports {
+ struct {
+ __u16 src;
+ __u16 dst;
+ } p16;
+ __u32 v32;
+};
+
+struct xt_hmark_info {
+ union nf_inet_addr src_mask; /* Source address mask */
+ union nf_inet_addr dst_mask; /* Dest address mask */
+ union hmark_ports port_mask;
+ union hmark_ports port_set;
+ __u32 spi_mask;
+ __u32 spi_set;
+ __u32 flags; /* Print out only */
+ __u16 proto_mask; /* L4 Proto mask */
+ __u32 hashrnd;
+ __u32 hmodulus; /* Modulus */
+ __u32 hoffset; /* Offset */
+};
+
+#endif /* XT_HMARK_H_ */
@@ -509,6 +509,21 @@ config NETFILTER_XT_TARGET_HL
since you can easily create immortal packets that loop
forever on the network.
+config NETFILTER_XT_TARGET_HMARK
+ tristate '"HMARK" target support'
+ depends on (IP6_NF_IPTABLES || IP6_NF_IPTABLES=n)
+ depends on NETFILTER_ADVANCED
+ ---help---
+ This option adds the "HMARK" target.
+
+ The target allows you to create rules in the "raw" and "mangle" tables
+ which set the skbuff mark by means of hash calculation within a given
+ range. The nfmark can influence the routing method (see "Use netfilter
+ MARK value as routing key") and can also be used by other subsystems to
+ change their behaviour.
+
+ To compile it as a module, choose M here. If unsure, say N.
+
config NETFILTER_XT_TARGET_IDLETIMER
tristate "IDLETIMER target support"
depends on NETFILTER_ADVANCED
@@ -59,6 +59,7 @@ obj-$(CONFIG_NETFILTER_XT_TARGET_CONNSECMARK) += xt_CONNSECMARK.o
obj-$(CONFIG_NETFILTER_XT_TARGET_CT) += xt_CT.o
obj-$(CONFIG_NETFILTER_XT_TARGET_DSCP) += xt_DSCP.o
obj-$(CONFIG_NETFILTER_XT_TARGET_HL) += xt_HL.o
+obj-$(CONFIG_NETFILTER_XT_TARGET_HMARK) += xt_HMARK.o
obj-$(CONFIG_NETFILTER_XT_TARGET_LED) += xt_LED.o
obj-$(CONFIG_NETFILTER_XT_TARGET_LOG) += xt_LOG.o
obj-$(CONFIG_NETFILTER_XT_TARGET_NFLOG) += xt_NFLOG.o
new file mode 100644
@@ -0,0 +1,371 @@
+/*
+ * xt_HMARK - Netfilter module to set mark as hash value
+ *
+ * (C) 2012 by Hans Schillstrom <hans.schillstrom@ericsson.com>
+ * (C) 2012 by Pablo Neira Ayuso <pablo@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.
+ *
+ * Description:
+ *
+ * This module calculates a hash value that can be modified by modulus and an
+ * offset, i.e. it is possible to produce a skb->mark within a range The hash
+ * value is based on a direction independent five tuple: src & dst addr src &
+ * dst ports and protocol.
+ */
+
+#include <linux/module.h>
+#include <linux/skbuff.h>
+#include <linux/icmp.h>
+
+#include <linux/netfilter/x_tables.h>
+#include <linux/netfilter/xt_HMARK.h>
+
+#include <net/ip.h>
+#if IS_ENABLED(CONFIG_NF_CONNTRACK)
+#include <net/netfilter/nf_conntrack.h>
+#endif
+#if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
+#include <net/ipv6.h>
+#include <linux/netfilter_ipv6/ip6_tables.h>
+#endif
+
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Hans Schillstrom <hans.schillstrom@ericsson.com>");
+MODULE_DESCRIPTION("Xtables: packet marking using hash calculation");
+MODULE_ALIAS("ipt_HMARK");
+MODULE_ALIAS("ip6t_HMARK");
+
+struct hmark_tuple {
+ u32 src;
+ u32 dst;
+ union hmark_ports uports;
+ uint8_t proto;
+};
+
+static int
+hmark_ct_set_htuple(const struct sk_buff *skb, struct hmark_tuple *t,
+ const struct xt_hmark_info *info);
+static inline u32
+hmark_hash(struct hmark_tuple *t, const struct xt_hmark_info *info)
+{
+ u32 hash;
+
+ if (t->dst < t->src)
+ swap(t->src, t->dst);
+
+ hash = jhash_3words(t->src, t->dst, t->uports.v32, info->hashrnd);
+ hash = hash ^ (t->proto & info->proto_mask);
+
+ return (hash % info->hmodulus) + info->hoffset;
+}
+
+static void
+hmark_set_tuple_ports(const struct sk_buff *skb, unsigned int nhoff,
+ struct hmark_tuple *t, const struct xt_hmark_info *info)
+{
+ int protoff;
+
+ protoff = proto_ports_offset(t->proto);
+ if (protoff < 0)
+ return;
+
+ nhoff += protoff;
+ if (skb_copy_bits(skb, nhoff, &t->uports, sizeof(t->uports)) < 0)
+ return;
+
+ if (t->proto == IPPROTO_ESP || t->proto == IPPROTO_AH)
+ t->uports.v32 = (t->uports.v32 & info->spi_mask) |
+ info->spi_set;
+ else {
+ t->uports.v32 = (t->uports.v32 & info->port_mask.v32) |
+ info->port_set.v32;
+
+ if (t->uports.p16.dst < t->uports.p16.src)
+ swap(t->uports.p16.dst, t->uports.p16.src);
+ }
+}
+
+#if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
+static int get_inner6_hdr(const struct sk_buff *skb, int *offset)
+{
+ struct icmp6hdr *icmp6h, _ih6;
+
+ icmp6h = skb_header_pointer(skb, *offset, sizeof(_ih6), &_ih6);
+ if (icmp6h == NULL)
+ return 0;
+
+ if (icmp6h->icmp6_type && icmp6h->icmp6_type < 128) {
+ *offset += sizeof(struct icmp6hdr);
+ return 1;
+ }
+ return 0;
+}
+
+static inline u32 hmark_addr6_mask(const __u32 *addr32, const __u32 *mask)
+{
+ return (addr32[0] & mask[0]) ^
+ (addr32[1] & mask[1]) ^
+ (addr32[2] & mask[2]) ^
+ (addr32[3] & mask[3]);
+}
+
+static int
+hmark_pkt_set_htuple_ipv6(const struct sk_buff *skb, struct hmark_tuple *t,
+ const struct xt_hmark_info *info)
+{
+ struct ipv6hdr *ip6, _ip6;
+ int flag = IP6T_FH_F_AUTH; /* Ports offset, find_hdr flags */
+ unsigned int nhoff = 0;
+ u16 fragoff = 0;
+ int nexthdr;
+
+ ip6 = (struct ipv6hdr *) (skb->data + skb_network_offset(skb));
+ nexthdr = ipv6_find_hdr(skb, &nhoff, -1, &fragoff, &flag);
+ if (nexthdr < 0)
+ return 0;
+ /* No need to check for icmp errors on fragments */
+ if ((flag & IP6T_FH_F_FRAG) || (nexthdr != IPPROTO_ICMPV6))
+ goto noicmp;
+ /* if an icmp error, use the inner header */
+ if (get_inner6_hdr(skb, &nhoff)) {
+ ip6 = skb_header_pointer(skb, nhoff, sizeof(_ip6), &_ip6);
+ if (ip6 == NULL)
+ return -1;
+ /* Treat AH as ESP, use SPI nothing else. */
+ flag = IP6T_FH_F_AUTH;
+ nexthdr = ipv6_find_hdr(skb, &nhoff, -1, &fragoff, &flag);
+ if (nexthdr < 0)
+ return -1;
+ }
+noicmp:
+ t->src = hmark_addr6_mask(ip6->saddr.s6_addr32, info->src_mask.all);
+ t->dst = hmark_addr6_mask(ip6->daddr.s6_addr32, info->dst_mask.all);
+
+ if (info->flags & XT_F_HMARK_METHOD_L3)
+ return 0;
+
+ t->proto = nexthdr;
+
+ if (t->proto == IPPROTO_ICMPV6)
+ return 0;
+
+ if (flag & IP6T_FH_F_FRAG)
+ return -1;
+
+ hmark_set_tuple_ports(skb, nhoff, t, info);
+
+ return 0;
+}
+
+static unsigned int
+hmark_tg_v6(struct sk_buff *skb, const struct xt_action_param *par)
+{
+ const struct xt_hmark_info *info = par->targinfo;
+ struct hmark_tuple t;
+
+ memset(&t, 0, sizeof(struct hmark_tuple));
+
+ if (info->flags & XT_F_HMARK_CT) {
+ if (hmark_ct_set_htuple(skb, &t, info) < 0)
+ return XT_CONTINUE;
+ } else {
+ if (hmark_pkt_set_htuple_ipv6(skb, &t, info) < 0)
+ return XT_CONTINUE;
+ }
+
+ skb->mark = hmark_hash(&t, info);
+ return XT_CONTINUE;
+}
+
+static inline u32
+hmark_addr_any_mask(int l3num, const __u32 *addr32, const __u32 *mask)
+{
+ if (l3num == AF_INET)
+ return *addr32 & *mask;
+
+ return hmark_addr6_mask(addr32, mask);
+}
+#else
+static inline u32
+hmark_addr_any_mask(int l3num, const __u32 *addr32, const __u32 *mask)
+{
+ return *addr32 & *mask;
+}
+
+#endif
+
+static int
+hmark_ct_set_htuple(const struct sk_buff *skb, struct hmark_tuple *t,
+ const struct xt_hmark_info *info)
+{
+#if IS_ENABLED(CONFIG_NF_CONNTRACK)
+ enum ip_conntrack_info ctinfo;
+ struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
+ struct nf_conntrack_tuple *otuple;
+ struct nf_conntrack_tuple *rtuple;
+
+ if (ct == NULL || nf_ct_is_untracked(ct))
+ return -1;
+
+ otuple = &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple;
+ rtuple = &ct->tuplehash[IP_CT_DIR_REPLY].tuple;
+
+ t->src = hmark_addr_any_mask(otuple->src.l3num, otuple->src.u3.all,
+ info->src_mask.all);
+ t->dst = hmark_addr_any_mask(otuple->src.l3num, rtuple->src.u3.all,
+ info->dst_mask.all);
+
+ if (info->flags & XT_F_HMARK_METHOD_L3)
+ return 0;
+
+ t->proto = nf_ct_protonum(ct);
+ if (t->proto != IPPROTO_ICMP) {
+ t->uports.p16.src = otuple->src.u.all;
+ t->uports.p16.dst = rtuple->src.u.all;
+ t->uports.v32 = (t->uports.v32 & info->port_mask.v32) |
+ info->port_set.v32;
+ if (t->uports.p16.dst < t->uports.p16.src)
+ swap(t->uports.p16.dst, t->uports.p16.src);
+ }
+
+ return 0;
+#else
+ return -1;
+#endif
+}
+
+static int get_inner_hdr(const struct sk_buff *skb, int iphsz, int *nhoff)
+{
+ const struct icmphdr *icmph;
+ struct icmphdr _ih;
+
+ /* Not enough header? */
+ icmph = skb_header_pointer(skb, *nhoff + iphsz, sizeof(_ih), &_ih);
+ if (icmph == NULL && icmph->type > NR_ICMP_TYPES)
+ return 0;
+
+ /* Error message? */
+ if (icmph->type != ICMP_DEST_UNREACH &&
+ icmph->type != ICMP_SOURCE_QUENCH &&
+ icmph->type != ICMP_TIME_EXCEEDED &&
+ icmph->type != ICMP_PARAMETERPROB &&
+ icmph->type != ICMP_REDIRECT)
+ return 0;
+
+ *nhoff += iphsz + sizeof(_ih);
+ return 1;
+}
+
+static int
+hmark_pkt_set_htuple_ipv4(const struct sk_buff *skb, struct hmark_tuple *t,
+ const struct xt_hmark_info *info)
+{
+ struct iphdr *ip, _ip;
+ int nhoff = skb_network_offset(skb);
+
+ ip = (struct iphdr *) (skb->data + nhoff);
+ if (ip->protocol == IPPROTO_ICMP) {
+ /* use inner header in case of ICMP errors */
+ if (get_inner_hdr(skb, ip->ihl * 4, &nhoff)) {
+ ip = skb_header_pointer(skb, nhoff, sizeof(_ip), &_ip);
+ if (ip == NULL)
+ return -1;
+ }
+ }
+
+ t->src = (__force u32) ip->saddr;
+ t->dst = (__force u32) ip->daddr;
+
+ t->src &= info->src_mask.ip;
+ t->dst &= info->dst_mask.ip;
+
+ if (info->flags & XT_F_HMARK_METHOD_L3)
+ return 0;
+
+ t->proto = ip->protocol;
+
+ /* ICMP has no ports, skip */
+ if (t->proto == IPPROTO_ICMP)
+ return 0;
+
+ /* follow-up fragments don't contain ports, skip */
+ if (ip->frag_off & htons(IP_MF | IP_OFFSET))
+ return -1;
+
+ hmark_set_tuple_ports(skb, (ip->ihl * 4) + nhoff, t, info);
+
+ return 0;
+}
+
+static unsigned int
+hmark_tg_v4(struct sk_buff *skb, const struct xt_action_param *par)
+{
+ const struct xt_hmark_info *info = par->targinfo;
+ struct hmark_tuple t;
+
+ memset(&t, 0, sizeof(struct hmark_tuple));
+
+ if (info->flags & XT_F_HMARK_CT) {
+ if (hmark_ct_set_htuple(skb, &t, info) < 0)
+ return XT_CONTINUE;
+ } else {
+ if (hmark_pkt_set_htuple_ipv4(skb, &t, info) < 0)
+ return XT_CONTINUE;
+ }
+
+ skb->mark = hmark_hash(&t, info);
+ return XT_CONTINUE;
+}
+
+static int hmark_tg_check(const struct xt_tgchk_param *par)
+{
+ const struct xt_hmark_info *info = par->targinfo;
+
+ if (!info->hmodulus) {
+ pr_info("xt_HMARK: hash modulus can't be zero\n");
+ return -EINVAL;
+ }
+ if (info->proto_mask && (info->flags & XT_F_HMARK_METHOD_L3)) {
+ pr_info("xt_HMARK: proto mask must be zero with L3 mode\n");
+ return -EINVAL;
+ }
+ return 0;
+}
+
+static struct xt_target hmark_tg_reg[] __read_mostly = {
+ {
+ .name = "HMARK",
+ .family = NFPROTO_IPV4,
+ .target = hmark_tg_v4,
+ .targetsize = sizeof(struct xt_hmark_info),
+ .checkentry = hmark_tg_check,
+ .me = THIS_MODULE,
+ },
+#if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
+ {
+ .name = "HMARK",
+ .family = NFPROTO_IPV6,
+ .target = hmark_tg_v6,
+ .targetsize = sizeof(struct xt_hmark_info),
+ .checkentry = hmark_tg_check,
+ .me = THIS_MODULE,
+ },
+#endif
+};
+
+static int __init hmark_tg_init(void)
+{
+ return xt_register_targets(hmark_tg_reg, ARRAY_SIZE(hmark_tg_reg));
+}
+
+static void __exit hmark_tg_exit(void)
+{
+ xt_unregister_targets(hmark_tg_reg, ARRAY_SIZE(hmark_tg_reg));
+}
+
+module_init(hmark_tg_init);
+module_exit(hmark_tg_exit);
--
1.7.2.3