From cf308a1fae432f315989e2da6878bfaa3daa22b1 Mon Sep 17 00:00:00 2001 From: Hans Schillstrom Date: Wed, 2 May 2012 07:49:47 +0000 Subject: [PATCH] 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. [ Part of this patch has been refactorized and modified by Pablo Neira Ayuso ] Signed-off-by: Hans Schillstrom Signed-off-by: Pablo Neira Ayuso --- include/linux/netfilter/xt_HMARK.h | 45 ++++ net/netfilter/Kconfig | 15 ++ net/netfilter/Makefile | 1 + net/netfilter/xt_HMARK.c | 362 +++++++++++++++++++++++++++++ 4 files changed, 423 insertions(+) create mode 100644 include/linux/netfilter/xt_HMARK.h create mode 100644 net/netfilter/xt_HMARK.c diff --git a/include/linux/netfilter/xt_HMARK.h b/include/linux/netfilter/xt_HMARK.h new file mode 100644 index 000000000000..abb1650940d2 --- /dev/null +++ b/include/linux/netfilter/xt_HMARK.h @@ -0,0 +1,45 @@ +#ifndef XT_HMARK_H_ +#define XT_HMARK_H_ + +#include + +enum { + XT_HMARK_SADDR_MASK, + XT_HMARK_DADDR_MASK, + XT_HMARK_SPI, + XT_HMARK_SPI_MASK, + XT_HMARK_SPORT, + XT_HMARK_DPORT, + XT_HMARK_SPORT_MASK, + XT_HMARK_DPORT_MASK, + XT_HMARK_PROTO_MASK, + XT_HMARK_RND, + XT_HMARK_MODULUS, + XT_HMARK_OFFSET, + XT_HMARK_CT, + XT_HMARK_METHOD_L3, + XT_HMARK_METHOD_L3_4, +}; +#define XT_HMARK_FLAG(flag) (1 << flag) + +union hmark_ports { + struct { + __u16 src; + __u16 dst; + } p16; + __u32 v32; +}; + +struct xt_hmark_info { + union nf_inet_addr src_mask; + union nf_inet_addr dst_mask; + union hmark_ports port_mask; + union hmark_ports port_set; + __u32 flags; + __u16 proto_mask; + __u32 hashrnd; + __u32 hmodulus; + __u32 hoffset; /* Mark offset to start from */ +}; + +#endif /* XT_HMARK_H_ */ diff --git a/net/netfilter/Kconfig b/net/netfilter/Kconfig index 0c6f67e8f2e5..209c1ed43368 100644 --- a/net/netfilter/Kconfig +++ b/net/netfilter/Kconfig @@ -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 diff --git a/net/netfilter/Makefile b/net/netfilter/Makefile index ca3676586f51..4e7960cc7b97 100644 --- a/net/netfilter/Makefile +++ b/net/netfilter/Makefile @@ -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 diff --git a/net/netfilter/xt_HMARK.c b/net/netfilter/xt_HMARK.c new file mode 100644 index 000000000000..32fbd735d02b --- /dev/null +++ b/net/netfilter/xt_HMARK.c @@ -0,0 +1,362 @@ +/* + * xt_HMARK - Netfilter module to set mark by means of hashing + * + * (C) 2012 by Hans Schillstrom + * (C) 2012 by Pablo Neira Ayuso + * + * 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 +#if IS_ENABLED(CONFIG_NF_CONNTRACK) +#include +#endif +#if IS_ENABLED(CONFIG_IP6_NF_IPTABLES) +#include +#include +#endif + +MODULE_LICENSE("GPL"); +MODULE_AUTHOR("Hans Schillstrom "); +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 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 inline u32 +hmark_addr_mask(int l3num, const __u32 *addr32, const __u32 *mask) +{ + switch (l3num) { + case AF_INET: + return *addr32 & *mask; + case AF_INET6: + return hmark_addr6_mask(addr32, mask); + } + return 0; +} + +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_mask(otuple->src.l3num, otuple->src.u3.all, + info->src_mask.all); + t->dst = hmark_addr_mask(otuple->src.l3num, rtuple->src.u3.all, + info->dst_mask.all); + + if (info->flags & XT_HMARK_FLAG(XT_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 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; + + 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 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; + 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; + /* Use inner header in case of ICMP errors */ + if (get_inner6_hdr(skb, &nhoff)) { + ip6 = skb_header_pointer(skb, nhoff, sizeof(_ip6), &_ip6); + if (ip6 == NULL) + return -1; + /* If AH present, use SPI like in ESP. */ + 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_HMARK_FLAG(XT_HMARK_METHOD_L3)) + return 0; + + t->proto = nexthdr; + if (t->proto == IPPROTO_ICMPV6) + return 0; + + if (flag & IP6T_FH_F_FRAG) + return 0; + + 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_HMARK_FLAG(XT_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; +} +#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_HMARK_FLAG(XT_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 all fragments */ + if (ip->frag_off & htons(IP_MF | IP_OFFSET)) + return 0; + + 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_HMARK_FLAG(XT_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_HMARK_FLAG(XT_HMARK_METHOD_L3))) { + pr_info("xt_HMARK: proto mask must be zero with L3 mode\n"); + return -EINVAL; + } + if (info->flags & XT_HMARK_FLAG(XT_HMARK_SPI_MASK) && + (info->flags & (XT_HMARK_FLAG(XT_HMARK_SPORT_MASK) | + XT_HMARK_FLAG(XT_HMARK_DPORT_MASK)))) { + pr_info("xt_HMARK: spi-mask and port-mask can't be combined\n"); + return -EINVAL; + } + if (info->flags & XT_HMARK_FLAG(XT_HMARK_SPI) && + (info->flags & (XT_HMARK_FLAG(XT_HMARK_SPORT) | + XT_HMARK_FLAG(XT_HMARK_DPORT)))) { + pr_info("xt_HMARK: spi-set and port-set can't be combined\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); -- GitLab