// SPDX-License-Identifier: GPL-2.0-only
/*
* xt_HMARK - Netfilter module to set mark by means of hashing
*
* (C) 2012 by Hans Schillstrom <[email protected]>
* (C) 2012 by Pablo Neira Ayuso <[email protected]>
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#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 <[email protected]>");
MODULE_DESCRIPTION("Xtables: packet marking using hash calculation");
MODULE_ALIAS("ipt_HMARK");
MODULE_ALIAS("ip6t_HMARK");
struct hmark_tuple {
__be32 src;
__be32 dst;
union hmark_ports uports;
u8 proto;
};
static inline __be32 hmark_addr6_mask(const __be32 *addr32, const __be32 *mask)
{
return (addr32[0] & mask[0]) ^
(addr32[1] & mask[1]) ^
(addr32[2] & mask[2]) ^
(addr32[3] & mask[3]);
}
static inline __be32
hmark_addr_mask(int l3num, const __be32 *addr32, const __be32 *mask)
{
switch (l3num) {
case AF_INET:
return *addr32 & *mask;
case AF_INET6:
return hmark_addr6_mask(addr32, mask);
}
return 0;
}
static inline void hmark_swap_ports(union hmark_ports *uports,
const struct xt_hmark_info *info)
{
union hmark_ports hp;
u16 src, dst;
hp.b32 = (uports->b32 & info->port_mask.b32) | info->port_set.b32;
src = ntohs(hp.b16.src);
dst = ntohs(hp.b16.dst);
if (dst > src)
uports->v32 = (dst << 16) | src;
else
uports->v32 = (src << 16) | dst;
}
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)
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.ip6,
info->src_mask.ip6);
t->dst = hmark_addr_mask(otuple->src.l3num, rtuple->src.u3.ip6,
info->dst_mask.ip6);
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.b16.src = otuple->src.u.all;
t->uports.b16.dst = rtuple->src.u.all;
hmark_swap_ports(&t->uports, info);
}
return 0;
#else
return -1;
#endif
}
/* This hash function is endian independent, to ensure consistent hashing if
* the cluster is composed of big and little endian systems. */
static inline u32
hmark_hash(struct hmark_tuple *t, const struct xt_hmark_info *info)
{
u32 hash;
u32 src = ntohl(t->src);
u32 dst = ntohl(t->dst);
if (dst < src)
swap(src, dst);
hash = jhash_3words(src, dst, t->uports.v32, info->hashrnd);
hash = hash ^ (t->proto & info->proto_mask);
return reciprocal_scale(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;
hmark_swap_ports(&t->uports, info);
}
#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 = IP6_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 & IP6_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 = IP6_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.ip6);
t->dst = hmark_addr6_mask(ip6->daddr.s6_addr32, info->dst_mask.ip6);
if (info->flags & XT_HMARK_FLAG(XT_HMARK_METHOD_L3))
return 0;
t->proto = nexthdr;
if (t->proto == IPPROTO_ICMPV6)
return 0;
if (flag & IP6_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 (!icmp_is_err(icmph->type))
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 = ip->saddr & info->src_mask.ip;
t->dst = ip->daddr & 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_is_fragment(ip))
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;
const char *errmsg = "proto mask must be zero with L3 mode";
if (!info->hmodulus)
return -EINVAL;
if (info->proto_mask &&
(info->flags & XT_HMARK_FLAG(XT_HMARK_METHOD_L3)))
goto err;
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))))
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)))) {
errmsg = "spi-set and port-set can't be combined";
goto err;
}
return 0;
err:
pr_info_ratelimited("%s\n", errmsg);
return -EINVAL;
}
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);
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