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