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Linux/net/netfilter/xt_multiport.c

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  1 /* Kernel module to match one of a list of TCP/UDP(-Lite)/SCTP/DCCP ports:
  2    ports are in 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 #include <linux/in.h>
 17 
 18 #include <linux/netfilter/xt_multiport.h>
 19 #include <linux/netfilter/x_tables.h>
 20 #include <linux/netfilter_ipv4/ip_tables.h>
 21 #include <linux/netfilter_ipv6/ip6_tables.h>
 22 
 23 MODULE_LICENSE("GPL");
 24 MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>");
 25 MODULE_DESCRIPTION("Xtables: multiple port matching for TCP, UDP, UDP-Lite, SCTP and DCCP");
 26 MODULE_ALIAS("ipt_multiport");
 27 MODULE_ALIAS("ip6t_multiport");
 28 
 29 #if 0
 30 #define duprintf(format, args...) printk(format , ## args)
 31 #else
 32 #define duprintf(format, args...)
 33 #endif
 34 
 35 /* Returns 1 if the port is matched by the test, 0 otherwise. */
 36 static inline bool
 37 ports_match_v0(const u_int16_t *portlist, enum xt_multiport_flags flags,
 38                u_int8_t count, u_int16_t src, u_int16_t dst)
 39 {
 40         unsigned int i;
 41         for (i = 0; i < count; i++) {
 42                 if (flags != XT_MULTIPORT_DESTINATION && portlist[i] == src)
 43                         return true;
 44 
 45                 if (flags != XT_MULTIPORT_SOURCE && portlist[i] == dst)
 46                         return true;
 47         }
 48 
 49         return false;
 50 }
 51 
 52 /* Returns 1 if the port is matched by the test, 0 otherwise. */
 53 static inline bool
 54 ports_match_v1(const struct xt_multiport_v1 *minfo,
 55                u_int16_t src, u_int16_t dst)
 56 {
 57         unsigned int i;
 58         u_int16_t s, e;
 59 
 60         for (i = 0; i < minfo->count; i++) {
 61                 s = minfo->ports[i];
 62 
 63                 if (minfo->pflags[i]) {
 64                         /* range port matching */
 65                         e = minfo->ports[++i];
 66                         duprintf("src or dst matches with %d-%d?\n", s, e);
 67 
 68                         if (minfo->flags == XT_MULTIPORT_SOURCE
 69                             && src >= s && src <= e)
 70                                 return true ^ minfo->invert;
 71                         if (minfo->flags == XT_MULTIPORT_DESTINATION
 72                             && dst >= s && dst <= e)
 73                                 return true ^ minfo->invert;
 74                         if (minfo->flags == XT_MULTIPORT_EITHER
 75                             && ((dst >= s && dst <= e)
 76                                 || (src >= s && src <= e)))
 77                                 return true ^ minfo->invert;
 78                 } else {
 79                         /* exact port matching */
 80                         duprintf("src or dst matches with %d?\n", s);
 81 
 82                         if (minfo->flags == XT_MULTIPORT_SOURCE
 83                             && src == s)
 84                                 return true ^ minfo->invert;
 85                         if (minfo->flags == XT_MULTIPORT_DESTINATION
 86                             && dst == s)
 87                                 return true ^ minfo->invert;
 88                         if (minfo->flags == XT_MULTIPORT_EITHER
 89                             && (src == s || dst == s))
 90                                 return true ^ minfo->invert;
 91                 }
 92         }
 93 
 94         return minfo->invert;
 95 }
 96 
 97 static bool
 98 multiport_mt_v0(const struct sk_buff *skb, const struct xt_match_param *par)
 99 {
100         const __be16 *pptr;
101         __be16 _ports[2];
102         const struct xt_multiport *multiinfo = par->matchinfo;
103 
104         if (par->fragoff != 0)
105                 return false;
106 
107         pptr = skb_header_pointer(skb, par->thoff, sizeof(_ports), _ports);
108         if (pptr == NULL) {
109                 /* We've been asked to examine this packet, and we
110                  * can't.  Hence, no choice but to drop.
111                  */
112                 duprintf("xt_multiport: Dropping evil offset=0 tinygram.\n");
113                 *par->hotdrop = true;
114                 return false;
115         }
116 
117         return ports_match_v0(multiinfo->ports, multiinfo->flags,
118                multiinfo->count, ntohs(pptr[0]), ntohs(pptr[1]));
119 }
120 
121 static bool
122 multiport_mt(const struct sk_buff *skb, const struct xt_match_param *par)
123 {
124         const __be16 *pptr;
125         __be16 _ports[2];
126         const struct xt_multiport_v1 *multiinfo = par->matchinfo;
127 
128         if (par->fragoff != 0)
129                 return false;
130 
131         pptr = skb_header_pointer(skb, par->thoff, sizeof(_ports), _ports);
132         if (pptr == NULL) {
133                 /* We've been asked to examine this packet, and we
134                  * can't.  Hence, no choice but to drop.
135                  */
136                 duprintf("xt_multiport: Dropping evil offset=0 tinygram.\n");
137                 *par->hotdrop = true;
138                 return false;
139         }
140 
141         return ports_match_v1(multiinfo, ntohs(pptr[0]), ntohs(pptr[1]));
142 }
143 
144 static inline bool
145 check(u_int16_t proto,
146       u_int8_t ip_invflags,
147       u_int8_t match_flags,
148       u_int8_t count)
149 {
150         /* Must specify supported protocol, no unknown flags or bad count */
151         return (proto == IPPROTO_TCP || proto == IPPROTO_UDP
152                 || proto == IPPROTO_UDPLITE
153                 || proto == IPPROTO_SCTP || proto == IPPROTO_DCCP)
154                 && !(ip_invflags & XT_INV_PROTO)
155                 && (match_flags == XT_MULTIPORT_SOURCE
156                     || match_flags == XT_MULTIPORT_DESTINATION
157                     || match_flags == XT_MULTIPORT_EITHER)
158                 && count <= XT_MULTI_PORTS;
159 }
160 
161 static bool multiport_mt_check_v0(const struct xt_mtchk_param *par)
162 {
163         const struct ipt_ip *ip = par->entryinfo;
164         const struct xt_multiport *multiinfo = par->matchinfo;
165 
166         return check(ip->proto, ip->invflags, multiinfo->flags,
167                      multiinfo->count);
168 }
169 
170 static bool multiport_mt_check(const struct xt_mtchk_param *par)
171 {
172         const struct ipt_ip *ip = par->entryinfo;
173         const struct xt_multiport_v1 *multiinfo = par->matchinfo;
174 
175         return check(ip->proto, ip->invflags, multiinfo->flags,
176                      multiinfo->count);
177 }
178 
179 static bool multiport_mt6_check_v0(const struct xt_mtchk_param *par)
180 {
181         const struct ip6t_ip6 *ip = par->entryinfo;
182         const struct xt_multiport *multiinfo = par->matchinfo;
183 
184         return check(ip->proto, ip->invflags, multiinfo->flags,
185                      multiinfo->count);
186 }
187 
188 static bool multiport_mt6_check(const struct xt_mtchk_param *par)
189 {
190         const struct ip6t_ip6 *ip = par->entryinfo;
191         const struct xt_multiport_v1 *multiinfo = par->matchinfo;
192 
193         return check(ip->proto, ip->invflags, multiinfo->flags,
194                      multiinfo->count);
195 }
196 
197 static struct xt_match multiport_mt_reg[] __read_mostly = {
198         {
199                 .name           = "multiport",
200                 .family         = NFPROTO_IPV4,
201                 .revision       = 0,
202                 .checkentry     = multiport_mt_check_v0,
203                 .match          = multiport_mt_v0,
204                 .matchsize      = sizeof(struct xt_multiport),
205                 .me             = THIS_MODULE,
206         },
207         {
208                 .name           = "multiport",
209                 .family         = NFPROTO_IPV4,
210                 .revision       = 1,
211                 .checkentry     = multiport_mt_check,
212                 .match          = multiport_mt,
213                 .matchsize      = sizeof(struct xt_multiport_v1),
214                 .me             = THIS_MODULE,
215         },
216         {
217                 .name           = "multiport",
218                 .family         = NFPROTO_IPV6,
219                 .revision       = 0,
220                 .checkentry     = multiport_mt6_check_v0,
221                 .match          = multiport_mt_v0,
222                 .matchsize      = sizeof(struct xt_multiport),
223                 .me             = THIS_MODULE,
224         },
225         {
226                 .name           = "multiport",
227                 .family         = NFPROTO_IPV6,
228                 .revision       = 1,
229                 .checkentry     = multiport_mt6_check,
230                 .match          = multiport_mt,
231                 .matchsize      = sizeof(struct xt_multiport_v1),
232                 .me             = THIS_MODULE,
233         },
234 };
235 
236 static int __init multiport_mt_init(void)
237 {
238         return xt_register_matches(multiport_mt_reg,
239                ARRAY_SIZE(multiport_mt_reg));
240 }
241 
242 static void __exit multiport_mt_exit(void)
243 {
244         xt_unregister_matches(multiport_mt_reg, ARRAY_SIZE(multiport_mt_reg));
245 }
246 
247 module_init(multiport_mt_init);
248 module_exit(multiport_mt_exit);
249 

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