net/netfilter/xt_multiport.c

   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 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  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 /* Returns 1 if the port is matched by the test, 0 otherwise. */
  30 static inline bool
  31 ports_match_v1(const struct xt_multiport_v1 *minfo,
  32                u_int16_t src, u_int16_t dst)
  33 {
  34         unsigned int i;
  35         u_int16_t s, e;
  36
  37         for (i = 0; i < minfo->count; i++) {
  38                 s = minfo->ports[i];
  39
  40                 if (minfo->pflags[i]) {
  41                         /* range port matching */
  42                         e = minfo->ports[++i];
  43                         pr_debug("src or dst matches with %d-%d?\n", s, e);
  44
  45                         if (minfo->flags == XT_MULTIPORT_SOURCE
  46                             && src >= s && src <= e)
  47                                 return true ^ minfo->invert;
  48                         if (minfo->flags == XT_MULTIPORT_DESTINATION
  49                             && dst >= s && dst <= e)
  50                                 return true ^ minfo->invert;
  51                         if (minfo->flags == XT_MULTIPORT_EITHER
  52                             && ((dst >= s && dst <= e)
  53                                 || (src >= s && src <= e)))
  54                                 return true ^ minfo->invert;
  55                 } else {
  56                         /* exact port matching */
  57                         pr_debug("src or dst matches with %d?\n", s);
  58
  59                         if (minfo->flags == XT_MULTIPORT_SOURCE
  60                             && src == s)
  61                                 return true ^ minfo->invert;
  62                         if (minfo->flags == XT_MULTIPORT_DESTINATION
  63                             && dst == s)
  64                                 return true ^ minfo->invert;
  65                         if (minfo->flags == XT_MULTIPORT_EITHER
  66                             && (src == s || dst == s))
  67                                 return true ^ minfo->invert;
  68                 }
  69         }
  70
  71         return minfo->invert;
  72 }
  73
  74 static bool
  75 multiport_mt(const struct sk_buff *skb, struct xt_action_param *par)
  76 {
  77         const __be16 *pptr;
  78         __be16 _ports[2];
  79         const struct xt_multiport_v1 *multiinfo = par->matchinfo;
  80
  81         if (par->fragoff != 0)
  82                 return false;
  83
  84         pptr = skb_header_pointer(skb, par->thoff, sizeof(_ports), _ports);
  85         if (pptr == NULL) {
  86                 /* We've been asked to examine this packet, and we
  87                  * can't.  Hence, no choice but to drop.
  88                  */
  89                 pr_debug("Dropping evil offset=0 tinygram.\n");
  90                 par->hotdrop = true;
  91                 return false;
  92         }
  93
  94         return ports_match_v1(multiinfo, ntohs(pptr[0]), ntohs(pptr[1]));
  95 }
  96
  97 static inline bool
  98 check(u_int16_t proto,
  99       u_int8_t ip_invflags,
 100       u_int8_t match_flags,
 101       u_int8_t count)
 102 {
 103         /* Must specify supported protocol, no unknown flags or bad count */
 104         return (proto == IPPROTO_TCP || proto == IPPROTO_UDP
 105                 || proto == IPPROTO_UDPLITE
 106                 || proto == IPPROTO_SCTP || proto == IPPROTO_DCCP)
 107                 && !(ip_invflags & XT_INV_PROTO)
 108                 && (match_flags == XT_MULTIPORT_SOURCE
 109                     || match_flags == XT_MULTIPORT_DESTINATION
 110                     || match_flags == XT_MULTIPORT_EITHER)
 111                 && count <= XT_MULTI_PORTS;
 112 }
 113
 114 static int multiport_mt_check(const struct xt_mtchk_param *par)
 115 {
 116         const struct ipt_ip *ip = par->entryinfo;
 117         const struct xt_multiport_v1 *multiinfo = par->matchinfo;
 118
 119         return check(ip->proto, ip->invflags, multiinfo->flags,
 120                      multiinfo->count) ? 0 : -EINVAL;
 121 }
 122
 123 static int multiport_mt6_check(const struct xt_mtchk_param *par)
 124 {
 125         const struct ip6t_ip6 *ip = par->entryinfo;
 126         const struct xt_multiport_v1 *multiinfo = par->matchinfo;
 127
 128         return check(ip->proto, ip->invflags, multiinfo->flags,
 129                      multiinfo->count) ? 0 : -EINVAL;
 130 }
 131
 132 static struct xt_match multiport_mt_reg[] __read_mostly = {
 133         {
 134                 .name           = "multiport",
 135                 .family         = NFPROTO_IPV4,
 136                 .revision       = 1,
 137                 .checkentry     = multiport_mt_check,
 138                 .match          = multiport_mt,
 139                 .matchsize      = sizeof(struct xt_multiport_v1),
 140                 .me             = THIS_MODULE,
 141         },
 142         {
 143                 .name           = "multiport",
 144                 .family         = NFPROTO_IPV6,
 145                 .revision       = 1,
 146                 .checkentry     = multiport_mt6_check,
 147                 .match          = multiport_mt,
 148                 .matchsize      = sizeof(struct xt_multiport_v1),
 149                 .me             = THIS_MODULE,
 150         },
 151 };
 152
 153 static int __init multiport_mt_init(void)
 154 {
 155         return xt_register_matches(multiport_mt_reg,
 156                ARRAY_SIZE(multiport_mt_reg));
 157 }
 158
 159 static void __exit multiport_mt_exit(void)
 160 {
 161         xt_unregister_matches(multiport_mt_reg, ARRAY_SIZE(multiport_mt_reg));
 162 }
 163
 164 module_init(multiport_mt_init);
 165 module_exit(multiport_mt_exit);