1 /* Kernel module to match one of a list of TCP/UDP ports: ports are in
2 the same place so we can treat them as equal. */
3
4 /* (C) 1999-2001 Paul `Rusty' Russell
5 * (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org>
6 *
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License version 2 as
9 * published by the Free Software Foundation.
10 */
11
12 #include <linux/module.h>
13 #include <linux/types.h>
14 #include <linux/udp.h>
15 #include <linux/skbuff.h>
16
17 #include <linux/netfilter_ipv4/ipt_multiport.h>
18 #include <linux/netfilter_ipv4/ip_tables.h>
19
20 MODULE_LICENSE("GPL");
21 MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>");
22 MODULE_DESCRIPTION("iptables multiple port match module");
23
24 #if 0
25 #define duprintf(format, args...) printk(format , ## args)
26 #else
27 #define duprintf(format, args...)
28 #endif
29
30 /* Returns 1 if the port is matched by the test, 0 otherwise. */
31 static inline int
32 ports_match(const u_int16_t *portlist, enum ipt_multiport_flags flags,
33 u_int8_t count, u_int16_t src, u_int16_t dst)
34 {
35 unsigned int i;
36 for (i=0; i<count; i++) {
37 if (flags != IPT_MULTIPORT_DESTINATION
38 && portlist[i] == src)
39 return 1;
40
41 if (flags != IPT_MULTIPORT_SOURCE
42 && portlist[i] == dst)
43 return 1;
44 }
45
46 return 0;
47 }
48
49 /* Returns 1 if the port is matched by the test, 0 otherwise. */
50 static inline int
51 ports_match_v1(const struct ipt_multiport_v1 *minfo,
52 u_int16_t src, u_int16_t dst)
53 {
54 unsigned int i;
55 u_int16_t s, e;
56
57 for (i=0; i < minfo->count; i++) {
58 s = minfo->ports[i];
59
60 if (minfo->pflags[i]) {
61 /* range port matching */
62 e = minfo->ports[++i];
63 duprintf("src or dst matches with %d-%d?\n", s, e);
64
65 if (minfo->flags == IPT_MULTIPORT_SOURCE
66 && src >= s && src <= e)
67 return 1 ^ minfo->invert;
68 if (minfo->flags == IPT_MULTIPORT_DESTINATION
69 && dst >= s && dst <= e)
70 return 1 ^ minfo->invert;
71 if (minfo->flags == IPT_MULTIPORT_EITHER
72 && ((dst >= s && dst <= e)
73 || (src >= s && src <= e)))
74 return 1 ^ minfo->invert;
75 } else {
76 /* exact port matching */
77 duprintf("src or dst matches with %d?\n", s);
78
79 if (minfo->flags == IPT_MULTIPORT_SOURCE
80 && src == s)
81 return 1 ^ minfo->invert;
82 if (minfo->flags == IPT_MULTIPORT_DESTINATION
83 && dst == s)
84 return 1 ^ minfo->invert;
85 if (minfo->flags == IPT_MULTIPORT_EITHER
86 && (src == s || dst == s))
87 return 1 ^ minfo->invert;
88 }
89 }
90
91 return minfo->invert;
92 }
93
94 static int
95 match(const struct sk_buff *skb,
96 const struct net_device *in,
97 const struct net_device *out,
98 const void *matchinfo,
99 int offset,
100 int *hotdrop)
101 {
102 u16 _ports[2], *pptr;
103 const struct ipt_multiport *multiinfo = matchinfo;
104
105 if (offset)
106 return 0;
107
108 pptr = skb_header_pointer(skb, skb->nh.iph->ihl * 4,
109 sizeof(_ports), _ports);
110 if (pptr == NULL) {
111 /* We've been asked to examine this packet, and we
112 * can't. Hence, no choice but to drop.
113 */
114 duprintf("ipt_multiport:"
115 " Dropping evil offset=0 tinygram.\n");
116 *hotdrop = 1;
117 return 0;
118 }
119
120 return ports_match(multiinfo->ports,
121 multiinfo->flags, multiinfo->count,
122 ntohs(pptr[0]), ntohs(pptr[1]));
123 }
124
125 static int
126 match_v1(const struct sk_buff *skb,
127 const struct net_device *in,
128 const struct net_device *out,
129 const void *matchinfo,
130 int offset,
131 int *hotdrop)
132 {
133 u16 _ports[2], *pptr;
134 const struct ipt_multiport_v1 *multiinfo = matchinfo;
135
136 if (offset)
137 return 0;
138
139 pptr = skb_header_pointer(skb, skb->nh.iph->ihl * 4,
140 sizeof(_ports), _ports);
141 if (pptr == NULL) {
142 /* We've been asked to examine this packet, and we
143 * can't. Hence, no choice but to drop.
144 */
145 duprintf("ipt_multiport:"
146 " Dropping evil offset=0 tinygram.\n");
147 *hotdrop = 1;
148 return 0;
149 }
150
151 return ports_match_v1(multiinfo, ntohs(pptr[0]), ntohs(pptr[1]));
152 }
153
154 /* Called when user tries to insert an entry of this type. */
155 static int
156 checkentry(const char *tablename,
157 const struct ipt_ip *ip,
158 void *matchinfo,
159 unsigned int matchsize,
160 unsigned int hook_mask)
161 {
162 return (matchsize == IPT_ALIGN(sizeof(struct ipt_multiport)));
163 }
164
165 static int
166 checkentry_v1(const char *tablename,
167 const struct ipt_ip *ip,
168 void *matchinfo,
169 unsigned int matchsize,
170 unsigned int hook_mask)
171 {
172 return (matchsize == IPT_ALIGN(sizeof(struct ipt_multiport_v1)));
173 }
174
175 static struct ipt_match multiport_match = {
176 .name = "multiport",
177 .revision = 0,
178 .match = &match,
179 .checkentry = &checkentry,
180 .me = THIS_MODULE,
181 };
182
183 static struct ipt_match multiport_match_v1 = {
184 .name = "multiport",
185 .revision = 1,
186 .match = &match_v1,
187 .checkentry = &checkentry_v1,
188 .me = THIS_MODULE,
189 };
190
191 static int __init init(void)
192 {
193 int err;
194
195 err = ipt_register_match(&multiport_match);
196 if (!err) {
197 err = ipt_register_match(&multiport_match_v1);
198 if (err)
199 ipt_unregister_match(&multiport_match);
200 }
201
202 return err;
203 }
204
205 static void __exit fini(void)
206 {
207 ipt_unregister_match(&multiport_match);
208 ipt_unregister_match(&multiport_match_v1);
209 }
210
211 module_init(init);
212 module_exit(fini);
213
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