// SPDX-License-Identifier: GPL-2.0-only
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/*
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* xt_HMARK - Netfilter module to set mark by means of hashing
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*
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* (C) 2012 by Hans Schillstrom <hans.schillstrom@ericsson.com>
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* (C) 2012 by Pablo Neira Ayuso <pablo@netfilter.org>
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*/
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/module.h>
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#include <linux/skbuff.h>
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#include <linux/icmp.h>
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#include <linux/netfilter/x_tables.h>
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#include <linux/netfilter/xt_HMARK.h>
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#include <net/ip.h>
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#if IS_ENABLED(CONFIG_NF_CONNTRACK)
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#include <net/netfilter/nf_conntrack.h>
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#endif
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#if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
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#include <net/ipv6.h>
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#include <linux/netfilter_ipv6/ip6_tables.h>
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#endif
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MODULE_LICENSE("GPL");
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MODULE_AUTHOR("Hans Schillstrom <hans.schillstrom@ericsson.com>");
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MODULE_DESCRIPTION("Xtables: packet marking using hash calculation");
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MODULE_ALIAS("ipt_HMARK");
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MODULE_ALIAS("ip6t_HMARK");
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struct hmark_tuple {
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__be32 src;
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__be32 dst;
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union hmark_ports uports;
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u8 proto;
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};
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static inline __be32 hmark_addr6_mask(const __be32 *addr32, const __be32 *mask)
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{
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return (addr32[0] & mask[0]) ^
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(addr32[1] & mask[1]) ^
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(addr32[2] & mask[2]) ^
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(addr32[3] & mask[3]);
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}
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static inline __be32
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hmark_addr_mask(int l3num, const __be32 *addr32, const __be32 *mask)
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{
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switch (l3num) {
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case AF_INET:
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return *addr32 & *mask;
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case AF_INET6:
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return hmark_addr6_mask(addr32, mask);
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}
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return 0;
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}
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static inline void hmark_swap_ports(union hmark_ports *uports,
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const struct xt_hmark_info *info)
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{
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union hmark_ports hp;
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u16 src, dst;
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hp.b32 = (uports->b32 & info->port_mask.b32) | info->port_set.b32;
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src = ntohs(hp.b16.src);
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dst = ntohs(hp.b16.dst);
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if (dst > src)
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uports->v32 = (dst << 16) | src;
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else
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uports->v32 = (src << 16) | dst;
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}
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static int
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hmark_ct_set_htuple(const struct sk_buff *skb, struct hmark_tuple *t,
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const struct xt_hmark_info *info)
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{
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#if IS_ENABLED(CONFIG_NF_CONNTRACK)
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enum ip_conntrack_info ctinfo;
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struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
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struct nf_conntrack_tuple *otuple;
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struct nf_conntrack_tuple *rtuple;
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if (ct == NULL)
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return -1;
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otuple = &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple;
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rtuple = &ct->tuplehash[IP_CT_DIR_REPLY].tuple;
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t->src = hmark_addr_mask(otuple->src.l3num, otuple->src.u3.ip6,
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info->src_mask.ip6);
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t->dst = hmark_addr_mask(otuple->src.l3num, rtuple->src.u3.ip6,
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info->dst_mask.ip6);
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if (info->flags & XT_HMARK_FLAG(XT_HMARK_METHOD_L3))
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return 0;
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t->proto = nf_ct_protonum(ct);
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if (t->proto != IPPROTO_ICMP) {
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t->uports.b16.src = otuple->src.u.all;
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t->uports.b16.dst = rtuple->src.u.all;
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hmark_swap_ports(&t->uports, info);
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}
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return 0;
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#else
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return -1;
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#endif
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}
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/* This hash function is endian independent, to ensure consistent hashing if
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* the cluster is composed of big and little endian systems. */
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static inline u32
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hmark_hash(struct hmark_tuple *t, const struct xt_hmark_info *info)
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{
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u32 hash;
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u32 src = ntohl(t->src);
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u32 dst = ntohl(t->dst);
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if (dst < src)
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swap(src, dst);
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hash = jhash_3words(src, dst, t->uports.v32, info->hashrnd);
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hash = hash ^ (t->proto & info->proto_mask);
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return reciprocal_scale(hash, info->hmodulus) + info->hoffset;
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}
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static void
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hmark_set_tuple_ports(const struct sk_buff *skb, unsigned int nhoff,
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struct hmark_tuple *t, const struct xt_hmark_info *info)
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{
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int protoff;
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protoff = proto_ports_offset(t->proto);
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if (protoff < 0)
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return;
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nhoff += protoff;
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if (skb_copy_bits(skb, nhoff, &t->uports, sizeof(t->uports)) < 0)
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return;
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hmark_swap_ports(&t->uports, info);
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}
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#if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
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static int get_inner6_hdr(const struct sk_buff *skb, int *offset)
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{
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struct icmp6hdr *icmp6h, _ih6;
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icmp6h = skb_header_pointer(skb, *offset, sizeof(_ih6), &_ih6);
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if (icmp6h == NULL)
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return 0;
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if (icmp6h->icmp6_type && icmp6h->icmp6_type < 128) {
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*offset += sizeof(struct icmp6hdr);
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return 1;
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}
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return 0;
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}
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static int
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hmark_pkt_set_htuple_ipv6(const struct sk_buff *skb, struct hmark_tuple *t,
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const struct xt_hmark_info *info)
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{
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struct ipv6hdr *ip6, _ip6;
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int flag = IP6_FH_F_AUTH;
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unsigned int nhoff = 0;
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u16 fragoff = 0;
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int nexthdr;
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ip6 = (struct ipv6hdr *) (skb->data + skb_network_offset(skb));
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nexthdr = ipv6_find_hdr(skb, &nhoff, -1, &fragoff, &flag);
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if (nexthdr < 0)
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return 0;
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/* No need to check for icmp errors on fragments */
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if ((flag & IP6_FH_F_FRAG) || (nexthdr != IPPROTO_ICMPV6))
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goto noicmp;
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/* Use inner header in case of ICMP errors */
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if (get_inner6_hdr(skb, &nhoff)) {
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ip6 = skb_header_pointer(skb, nhoff, sizeof(_ip6), &_ip6);
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if (ip6 == NULL)
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return -1;
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/* If AH present, use SPI like in ESP. */
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flag = IP6_FH_F_AUTH;
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nexthdr = ipv6_find_hdr(skb, &nhoff, -1, &fragoff, &flag);
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if (nexthdr < 0)
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return -1;
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}
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noicmp:
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t->src = hmark_addr6_mask(ip6->saddr.s6_addr32, info->src_mask.ip6);
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t->dst = hmark_addr6_mask(ip6->daddr.s6_addr32, info->dst_mask.ip6);
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if (info->flags & XT_HMARK_FLAG(XT_HMARK_METHOD_L3))
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return 0;
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t->proto = nexthdr;
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if (t->proto == IPPROTO_ICMPV6)
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return 0;
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if (flag & IP6_FH_F_FRAG)
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return 0;
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hmark_set_tuple_ports(skb, nhoff, t, info);
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return 0;
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}
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static unsigned int
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hmark_tg_v6(struct sk_buff *skb, const struct xt_action_param *par)
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{
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const struct xt_hmark_info *info = par->targinfo;
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struct hmark_tuple t;
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memset(&t, 0, sizeof(struct hmark_tuple));
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if (info->flags & XT_HMARK_FLAG(XT_HMARK_CT)) {
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if (hmark_ct_set_htuple(skb, &t, info) < 0)
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return XT_CONTINUE;
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} else {
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if (hmark_pkt_set_htuple_ipv6(skb, &t, info) < 0)
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return XT_CONTINUE;
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}
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skb->mark = hmark_hash(&t, info);
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return XT_CONTINUE;
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}
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#endif
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static int get_inner_hdr(const struct sk_buff *skb, int iphsz, int *nhoff)
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{
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const struct icmphdr *icmph;
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struct icmphdr _ih;
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/* Not enough header? */
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icmph = skb_header_pointer(skb, *nhoff + iphsz, sizeof(_ih), &_ih);
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if (icmph == NULL || icmph->type > NR_ICMP_TYPES)
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return 0;
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/* Error message? */
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if (!icmp_is_err(icmph->type))
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return 0;
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*nhoff += iphsz + sizeof(_ih);
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return 1;
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}
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static int
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hmark_pkt_set_htuple_ipv4(const struct sk_buff *skb, struct hmark_tuple *t,
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const struct xt_hmark_info *info)
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{
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struct iphdr *ip, _ip;
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int nhoff = skb_network_offset(skb);
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ip = (struct iphdr *) (skb->data + nhoff);
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if (ip->protocol == IPPROTO_ICMP) {
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/* Use inner header in case of ICMP errors */
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if (get_inner_hdr(skb, ip->ihl * 4, &nhoff)) {
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ip = skb_header_pointer(skb, nhoff, sizeof(_ip), &_ip);
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if (ip == NULL)
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return -1;
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}
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}
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t->src = ip->saddr & info->src_mask.ip;
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t->dst = ip->daddr & info->dst_mask.ip;
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if (info->flags & XT_HMARK_FLAG(XT_HMARK_METHOD_L3))
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return 0;
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t->proto = ip->protocol;
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/* ICMP has no ports, skip */
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if (t->proto == IPPROTO_ICMP)
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return 0;
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/* follow-up fragments don't contain ports, skip all fragments */
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if (ip_is_fragment(ip))
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return 0;
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hmark_set_tuple_ports(skb, (ip->ihl * 4) + nhoff, t, info);
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return 0;
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}
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static unsigned int
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hmark_tg_v4(struct sk_buff *skb, const struct xt_action_param *par)
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{
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const struct xt_hmark_info *info = par->targinfo;
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struct hmark_tuple t;
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memset(&t, 0, sizeof(struct hmark_tuple));
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if (info->flags & XT_HMARK_FLAG(XT_HMARK_CT)) {
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if (hmark_ct_set_htuple(skb, &t, info) < 0)
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return XT_CONTINUE;
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} else {
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if (hmark_pkt_set_htuple_ipv4(skb, &t, info) < 0)
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return XT_CONTINUE;
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}
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skb->mark = hmark_hash(&t, info);
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return XT_CONTINUE;
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}
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static int hmark_tg_check(const struct xt_tgchk_param *par)
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{
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const struct xt_hmark_info *info = par->targinfo;
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const char *errmsg = "proto mask must be zero with L3 mode";
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if (!info->hmodulus)
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return -EINVAL;
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if (info->proto_mask &&
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(info->flags & XT_HMARK_FLAG(XT_HMARK_METHOD_L3)))
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goto err;
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if (info->flags & XT_HMARK_FLAG(XT_HMARK_SPI_MASK) &&
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(info->flags & (XT_HMARK_FLAG(XT_HMARK_SPORT_MASK) |
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XT_HMARK_FLAG(XT_HMARK_DPORT_MASK))))
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return -EINVAL;
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if (info->flags & XT_HMARK_FLAG(XT_HMARK_SPI) &&
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(info->flags & (XT_HMARK_FLAG(XT_HMARK_SPORT) |
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XT_HMARK_FLAG(XT_HMARK_DPORT)))) {
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errmsg = "spi-set and port-set can't be combined";
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goto err;
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}
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return 0;
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err:
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pr_info_ratelimited("%s\n", errmsg);
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return -EINVAL;
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}
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static struct xt_target hmark_tg_reg[] __read_mostly = {
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{
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.name = "HMARK",
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.family = NFPROTO_IPV4,
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.target = hmark_tg_v4,
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.targetsize = sizeof(struct xt_hmark_info),
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.checkentry = hmark_tg_check,
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.me = THIS_MODULE,
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},
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#if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
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{
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.name = "HMARK",
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.family = NFPROTO_IPV6,
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.target = hmark_tg_v6,
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.targetsize = sizeof(struct xt_hmark_info),
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.checkentry = hmark_tg_check,
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.me = THIS_MODULE,
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},
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#endif
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};
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static int __init hmark_tg_init(void)
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{
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return xt_register_targets(hmark_tg_reg, ARRAY_SIZE(hmark_tg_reg));
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}
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static void __exit hmark_tg_exit(void)
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{
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xt_unregister_targets(hmark_tg_reg, ARRAY_SIZE(hmark_tg_reg));
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}
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module_init(hmark_tg_init);
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module_exit(hmark_tg_exit);
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