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
20 MODULE_LICENSE("GPL");
21 MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>");
22 MODULE_DESCRIPTION("Xtables: multiple port matching for TCP, UDP, UDP-Lite, SCTP and DCCP");
23 MODULE_ALIAS("ipt_multiport");
24 MODULE_ALIAS("ip6t_multiport");
25
26 /* Returns 1 if the port is matched by the test, 0 otherwise. */
27 static inline bool
ports_match_v1(const struct xt_multiport_v1 * minfo,u_int16_t src,u_int16_t dst)28 ports_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
85 static bool
multiport_mt(const struct sk_buff * skb,struct xt_action_param * par)86 multiport_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
108 static inline bool
check(u_int16_t proto,u_int8_t ip_invflags,u_int8_t match_flags,u_int8_t count)109 check(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
multiport_mt_check(const struct xt_mtchk_param * par)125 static 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
multiport_mt6_check(const struct xt_mtchk_param * par)134 static 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
143 static 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
multiport_mt_init(void)164 static int __init multiport_mt_init(void)
165 {
166 return xt_register_matches(multiport_mt_reg,
167 ARRAY_SIZE(multiport_mt_reg));
168 }
169
multiport_mt_exit(void)170 static void __exit multiport_mt_exit(void)
171 {
172 xt_unregister_matches(multiport_mt_reg, ARRAY_SIZE(multiport_mt_reg));
173 }
174
175 module_init(multiport_mt_init);
176 module_exit(multiport_mt_exit);
177