ebt_ip.c

  1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 *  ebt_ip
  4 *
  5 *	Authors:
  6 *	Bart De Schuymer <bdschuym@pandora.be>
  7 *
  8 *  April, 2002
  9 *
 10 *  Changes:
 11 *    added ip-sport and ip-dport
 12 *    Innominate Security Technologies AG <mhopf@innominate.com>
 13 *    September, 2002
 14 */
 15#include <linux/ip.h>
 16#include <net/ip.h>
 17#include <linux/in.h>
 18#include <linux/module.h>
 19#include <linux/netfilter/x_tables.h>
 20#include <linux/netfilter_bridge/ebtables.h>
 21#include <linux/netfilter_bridge/ebt_ip.h>
 22
 23union pkthdr {
 24	struct {
 25		__be16 src;
 26		__be16 dst;
 27	} tcpudphdr;
 28	struct {
 29		u8 type;
 30		u8 code;
 31	} icmphdr;
 32	struct {
 33		u8 type;
 34	} igmphdr;
 35};
 36
 37static bool
 38ebt_ip_mt(const struct sk_buff *skb, struct xt_action_param *par)
 39{
 40	const struct ebt_ip_info *info = par->matchinfo;
 41	const struct iphdr *ih;
 42	struct iphdr _iph;
 43	const union pkthdr *pptr;
 44	union pkthdr _pkthdr;
 45
 46	ih = skb_header_pointer(skb, 0, sizeof(_iph), &_iph);
 47	if (ih == NULL)
 48		return false;
 49	if ((info->bitmask & EBT_IP_TOS) &&
 50	    NF_INVF(info, EBT_IP_TOS, info->tos != ih->tos))
 51		return false;
 52	if ((info->bitmask & EBT_IP_SOURCE) &&
 53	    NF_INVF(info, EBT_IP_SOURCE,
 54		    (ih->saddr & info->smsk) != info->saddr))
 55		return false;
 56	if ((info->bitmask & EBT_IP_DEST) &&
 57	    NF_INVF(info, EBT_IP_DEST,
 58		    (ih->daddr & info->dmsk) != info->daddr))
 59		return false;
 60	if (info->bitmask & EBT_IP_PROTO) {
 61		if (NF_INVF(info, EBT_IP_PROTO, info->protocol != ih->protocol))
 62			return false;
 63		if (!(info->bitmask & (EBT_IP_DPORT | EBT_IP_SPORT |
 64				       EBT_IP_ICMP | EBT_IP_IGMP)))
 65			return true;
 66		if (ntohs(ih->frag_off) & IP_OFFSET)
 67			return false;
 68
 69		/* min icmp/igmp headersize is 4, so sizeof(_pkthdr) is ok. */
 70		pptr = skb_header_pointer(skb, ih->ihl*4,
 71					  sizeof(_pkthdr), &_pkthdr);
 72		if (pptr == NULL)
 73			return false;
 74		if (info->bitmask & EBT_IP_DPORT) {
 75			u32 dst = ntohs(pptr->tcpudphdr.dst);
 76			if (NF_INVF(info, EBT_IP_DPORT,
 77				    dst < info->dport[0] ||
 78				    dst > info->dport[1]))
 79				return false;
 80		}
 81		if (info->bitmask & EBT_IP_SPORT) {
 82			u32 src = ntohs(pptr->tcpudphdr.src);
 83			if (NF_INVF(info, EBT_IP_SPORT,
 84				    src < info->sport[0] ||
 85				    src > info->sport[1]))
 86				return false;
 87		}
 88		if ((info->bitmask & EBT_IP_ICMP) &&
 89		    NF_INVF(info, EBT_IP_ICMP,
 90			    pptr->icmphdr.type < info->icmp_type[0] ||
 91			    pptr->icmphdr.type > info->icmp_type[1] ||
 92			    pptr->icmphdr.code < info->icmp_code[0] ||
 93			    pptr->icmphdr.code > info->icmp_code[1]))
 94			return false;
 95		if ((info->bitmask & EBT_IP_IGMP) &&
 96		    NF_INVF(info, EBT_IP_IGMP,
 97			    pptr->igmphdr.type < info->igmp_type[0] ||
 98			    pptr->igmphdr.type > info->igmp_type[1]))
 99			return false;
100	}
101	return true;
102}
103
104static int ebt_ip_mt_check(const struct xt_mtchk_param *par)
105{
106	const struct ebt_ip_info *info = par->matchinfo;
107	const struct ebt_entry *e = par->entryinfo;
108
109	if (e->ethproto != htons(ETH_P_IP) ||
110	   e->invflags & EBT_IPROTO)
111		return -EINVAL;
112	if (info->bitmask & ~EBT_IP_MASK || info->invflags & ~EBT_IP_MASK)
113		return -EINVAL;
114	if (info->bitmask & (EBT_IP_DPORT | EBT_IP_SPORT)) {
115		if (info->invflags & EBT_IP_PROTO)
116			return -EINVAL;
117		if (info->protocol != IPPROTO_TCP &&
118		    info->protocol != IPPROTO_UDP &&
119		    info->protocol != IPPROTO_UDPLITE &&
120		    info->protocol != IPPROTO_SCTP &&
121		    info->protocol != IPPROTO_DCCP)
122			 return -EINVAL;
123	}
124	if (info->bitmask & EBT_IP_DPORT && info->dport[0] > info->dport[1])
125		return -EINVAL;
126	if (info->bitmask & EBT_IP_SPORT && info->sport[0] > info->sport[1])
127		return -EINVAL;
128	if (info->bitmask & EBT_IP_ICMP) {
129		if ((info->invflags & EBT_IP_PROTO) ||
130		    info->protocol != IPPROTO_ICMP)
131			return -EINVAL;
132		if (info->icmp_type[0] > info->icmp_type[1] ||
133		    info->icmp_code[0] > info->icmp_code[1])
134			return -EINVAL;
135	}
136	if (info->bitmask & EBT_IP_IGMP) {
137		if ((info->invflags & EBT_IP_PROTO) ||
138		    info->protocol != IPPROTO_IGMP)
139			return -EINVAL;
140		if (info->igmp_type[0] > info->igmp_type[1])
141			return -EINVAL;
142	}
143	return 0;
144}
145
146static struct xt_match ebt_ip_mt_reg __read_mostly = {
147	.name		= "ip",
148	.revision	= 0,
149	.family		= NFPROTO_BRIDGE,
150	.match		= ebt_ip_mt,
151	.checkentry	= ebt_ip_mt_check,
152	.matchsize	= sizeof(struct ebt_ip_info),
153	.me		= THIS_MODULE,
154};
155
156static int __init ebt_ip_init(void)
157{
158	return xt_register_match(&ebt_ip_mt_reg);
159}
160
161static void __exit ebt_ip_fini(void)
162{
163	xt_unregister_match(&ebt_ip_mt_reg);
164}
165
166module_init(ebt_ip_init);
167module_exit(ebt_ip_fini);
168MODULE_DESCRIPTION("Ebtables: IPv4 protocol packet match");
169MODULE_LICENSE("GPL");