net/ipv6/netfilter/ip6t_multiport.c

   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 #include <linux/in.h>
  17
  18 #include <linux/netfilter_ipv6/ip6t_multiport.h>
  19 #include <linux/netfilter_ipv6/ip6_tables.h>
  20
  21 MODULE_LICENSE("GPL");
  22 MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>");
  23 MODULE_DESCRIPTION("ip6tables match for multiple ports");
  24
  25 #if 0
  26 #define duprintf(format, args...) printk(format , ## args)
  27 #else
  28 #define duprintf(format, args...)
  29 #endif
  30
  31 /* Returns 1 if the port is matched by the test, 0 otherwise. */
  32 static inline int
  33 ports_match(const u_int16_t *portlist, enum ip6t_multiport_flags flags,
  34             u_int8_t count, u_int16_t src, u_int16_t dst)
  35 {
  36         unsigned int i;
  37         for (i=0; i<count; i++) {
  38                 if (flags != IP6T_MULTIPORT_DESTINATION
  39                     && portlist[i] == src)
  40                         return 1;
  41
  42                 if (flags != IP6T_MULTIPORT_SOURCE
  43                     && portlist[i] == dst)
  44                         return 1;
  45         }
  46
  47         return 0;
  48 }
  49
  50 static int
  51 match(const struct sk_buff *skb,
  52       const struct net_device *in,
  53       const struct net_device *out,
  54       const void *matchinfo,
  55       int offset,
  56       const void *hdr,
  57       u_int16_t datalen,
  58       int *hotdrop)
  59 {
  60         const struct udphdr *udp = hdr;
  61         const struct ip6t_multiport *multiinfo = matchinfo;
  62
  63         /* Must be big enough to read ports. */
  64         if (offset == 0 && datalen < sizeof(struct udphdr)) {
  65                 /* We've been asked to examine this packet, and we
  66                    can't.  Hence, no choice but to drop. */
  67                         duprintf("ip6t_multiport:"
  68                                  " Dropping evil offset=0 tinygram.\n");
  69                         *hotdrop = 1;
  70                         return 0;
  71         }
  72
  73         /* Must not be a fragment. */
  74         return !offset
  75                 && ports_match(multiinfo->ports,
  76                                multiinfo->flags, multiinfo->count,
  77                                ntohs(udp->source), ntohs(udp->dest));
  78 }
  79
  80 /* Called when user tries to insert an entry of this type. */
  81 static int
  82 checkentry(const char *tablename,
  83            const struct ip6t_ip6 *ip,
  84            void *matchinfo,
  85            unsigned int matchsize,
  86            unsigned int hook_mask)
  87 {
  88         const struct ip6t_multiport *multiinfo = matchinfo;
  89
  90         /* Must specify proto == TCP/UDP, no unknown flags or bad count */
  91         return (ip->proto == IPPROTO_TCP || ip->proto == IPPROTO_UDP)
  92                 && !(ip->flags & IP6T_INV_PROTO)
  93                 && matchsize == IP6T_ALIGN(sizeof(struct ip6t_multiport))
  94                 && (multiinfo->flags == IP6T_MULTIPORT_SOURCE
  95                     || multiinfo->flags == IP6T_MULTIPORT_DESTINATION
  96                     || multiinfo->flags == IP6T_MULTIPORT_EITHER)
  97                 && multiinfo->count <= IP6T_MULTI_PORTS;
  98 }
  99
 100 static struct ip6t_match multiport_match = {
 101         .name           = "multiport",
 102         .match          = &match,
 103         .checkentry     = &checkentry,
 104         .me             = THIS_MODULE,
 105 };
 106
 107 static int __init init(void)
 108 {
 109         return ip6t_register_match(&multiport_match);
 110 }
 111
 112 static void __exit fini(void)
 113 {
 114         ip6t_unregister_match(&multiport_match);
 115 }
 116
 117 module_init(init);
 118 module_exit(fini);