1// SPDX-License-Identifier: GPL-2.0-only
2/* Kernel module to match one of a list of TCP/UDP(-Lite)/SCTP/DCCP ports:
3   ports are in the same place so we can treat them as equal. */
4
5/* (C) 1999-2001 Paul `Rusty' Russell
6 * (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org>
7 */
8#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
9#include <linux/module.h>
10#include <linux/types.h>
11#include <linux/udp.h>
12#include <linux/skbuff.h>
13#include <linux/in.h>
14
15#include <linux/netfilter/xt_multiport.h>
16#include <linux/netfilter/x_tables.h>
17#include <linux/netfilter_ipv4/ip_tables.h>
18#include <linux/netfilter_ipv6/ip6_tables.h>
19
20MODULE_LICENSE("GPL");
21MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>");
22MODULE_DESCRIPTION("Xtables: multiple port matching for TCP, UDP, UDP-Lite, SCTP and DCCP");
23MODULE_ALIAS("ipt_multiport");
24MODULE_ALIAS("ip6t_multiport");
25
26/* Returns 1 if the port is matched by the test, 0 otherwise. */
27static inline bool
28ports_match_v1(const struct xt_multiport_v1 *minfo,
29	       u_int16_t src, u_int16_t dst)
30{
31	unsigned int i;
32	u_int16_t s, e;
33
34	for (i = 0; i < minfo->count; i++) {
35		s = minfo->ports[i];
36
37		if (minfo->pflags[i]) {
38			/* range port matching */
39			e = minfo->ports[++i];
40			pr_debug("src or dst matches with %d-%d?\n", s, e);
41
42			switch (minfo->flags) {
43			case XT_MULTIPORT_SOURCE:
44				if (src >= s && src <= e)
45					return true ^ minfo->invert;
46				break;
47			case XT_MULTIPORT_DESTINATION:
48				if (dst >= s && dst <= e)
49					return true ^ minfo->invert;
50				break;
51			case XT_MULTIPORT_EITHER:
52				if ((dst >= s && dst <= e) ||
53				    (src >= s && src <= e))
54					return true ^ minfo->invert;
55				break;
56			default:
57				break;
58			}
59		} else {
60			/* exact port matching */
61			pr_debug("src or dst matches with %d?\n", s);
62
63			switch (minfo->flags) {
64			case XT_MULTIPORT_SOURCE:
65				if (src == s)
66					return true ^ minfo->invert;
67				break;
68			case XT_MULTIPORT_DESTINATION:
69				if (dst == s)
70					return true ^ minfo->invert;
71				break;
72			case XT_MULTIPORT_EITHER:
73				if (src == s || dst == s)
74					return true ^ minfo->invert;
75				break;
76			default:
77				break;
78			}
79		}
80	}
81
82	return minfo->invert;
83}
84
85static bool
86multiport_mt(const struct sk_buff *skb, struct xt_action_param *par)
87{
88	const __be16 *pptr;
89	__be16 _ports[2];
90	const struct xt_multiport_v1 *multiinfo = par->matchinfo;
91
92	if (par->fragoff != 0)
93		return false;
94
95	pptr = skb_header_pointer(skb, par->thoff, sizeof(_ports), _ports);
96	if (pptr == NULL) {
97		/* We've been asked to examine this packet, and we
98		 * can't.  Hence, no choice but to drop.
99		 */
100		pr_debug("Dropping evil offset=0 tinygram.\n");
101		par->hotdrop = true;
102		return false;
103	}
104
105	return ports_match_v1(multiinfo, ntohs(pptr[0]), ntohs(pptr[1]));
106}
107
108static inline bool
109check(u_int16_t proto,
110      u_int8_t ip_invflags,
111      u_int8_t match_flags,
112      u_int8_t count)
113{
114	/* Must specify supported protocol, no unknown flags or bad count */
115	return (proto == IPPROTO_TCP || proto == IPPROTO_UDP
116		|| proto == IPPROTO_UDPLITE
117		|| proto == IPPROTO_SCTP || proto == IPPROTO_DCCP)
118		&& !(ip_invflags & XT_INV_PROTO)
119		&& (match_flags == XT_MULTIPORT_SOURCE
120		    || match_flags == XT_MULTIPORT_DESTINATION
121		    || match_flags == XT_MULTIPORT_EITHER)
122		&& count <= XT_MULTI_PORTS;
123}
124
125static int multiport_mt_check(const struct xt_mtchk_param *par)
126{
127	const struct ipt_ip *ip = par->entryinfo;
128	const struct xt_multiport_v1 *multiinfo = par->matchinfo;
129
130	return check(ip->proto, ip->invflags, multiinfo->flags,
131		     multiinfo->count) ? 0 : -EINVAL;
132}
133
134static int multiport_mt6_check(const struct xt_mtchk_param *par)
135{
136	const struct ip6t_ip6 *ip = par->entryinfo;
137	const struct xt_multiport_v1 *multiinfo = par->matchinfo;
138
139	return check(ip->proto, ip->invflags, multiinfo->flags,
140		     multiinfo->count) ? 0 : -EINVAL;
141}
142
143static struct xt_match multiport_mt_reg[] __read_mostly = {
144	{
145		.name		= "multiport",
146		.family		= NFPROTO_IPV4,
147		.revision	= 1,
148		.checkentry	= multiport_mt_check,
149		.match		= multiport_mt,
150		.matchsize	= sizeof(struct xt_multiport_v1),
151		.me		= THIS_MODULE,
152	},
153	{
154		.name		= "multiport",
155		.family		= NFPROTO_IPV6,
156		.revision	= 1,
157		.checkentry	= multiport_mt6_check,
158		.match		= multiport_mt,
159		.matchsize	= sizeof(struct xt_multiport_v1),
160		.me		= THIS_MODULE,
161	},
162};
163
164static int __init multiport_mt_init(void)
165{
166	return xt_register_matches(multiport_mt_reg,
167	       ARRAY_SIZE(multiport_mt_reg));
168}
169
170static void __exit multiport_mt_exit(void)
171{
172	xt_unregister_matches(multiport_mt_reg, ARRAY_SIZE(multiport_mt_reg));
173}
174
175module_init(multiport_mt_init);
176module_exit(multiport_mt_exit);
177