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                                 if (src >= s && src <= e)
  48                                         return true ^ minfo->invert;
  49                                 break;
  50                         case XT_MULTIPORT_DESTINATION:
  51                                 if (dst >= s && dst <= e)
  52                                         return true ^ minfo->invert;
  53                                 break;
  54                         case XT_MULTIPORT_EITHER:
  55                                 if ((dst >= s && dst <= e) ||
  56                                     (src >= s && src <= e))
  57                                         return true ^ minfo->invert;
  58                                 break;
  59                         default:
  60                                 break;
  61                         }
  62                 } else {
  63                         /* exact port matching */
  64                         pr_debug("src or dst matches with %d?\n", s);
  65
  66                         switch (minfo->flags) {
  67                         case XT_MULTIPORT_SOURCE:
  68                                 if (src == s)
  69                                         return true ^ minfo->invert;
  70                                 break;
  71                         case XT_MULTIPORT_DESTINATION:
  72                                 if (dst == s)
  73                                         return true ^ minfo->invert;
  74                                 break;
  75                         case XT_MULTIPORT_EITHER:
  76                                 if (src == s || dst == s)
  77                                         return true ^ minfo->invert;
  78                                 break;
  79                         default:
  80                                 break;
  81                         }
  82                 }
  83         }
  84
  85         return minfo->invert;
  86 }
  87
  88 static bool
  89 multiport_mt(const struct sk_buff *skb, struct xt_action_param *par)
  90 {
  91         const __be16 *pptr;
  92         __be16 _ports[2];
  93         const struct xt_multiport_v1 *multiinfo = par->matchinfo;
  94
  95         if (par->fragoff != 0)
  96                 return false;
  97
  98         pptr = skb_header_pointer(skb, par->thoff, sizeof(_ports), _ports);
  99         if (pptr == NULL) {
 100                 /* We've been asked to examine this packet, and we
 101                  * can't.  Hence, no choice but to drop.
 102                  */
 103                 pr_debug("Dropping evil offset=0 tinygram.\n");
 104                 par->hotdrop = true;
 105                 return false;
 106         }
 107
 108         return ports_match_v1(multiinfo, ntohs(pptr[0]), ntohs(pptr[1]));
 109 }
 110
 111 static inline bool
 112 check(u_int16_t proto,
 113       u_int8_t ip_invflags,
 114       u_int8_t match_flags,
 115       u_int8_t count)
 116 {
 117         /* Must specify supported protocol, no unknown flags or bad count */
 118         return (proto == IPPROTO_TCP || proto == IPPROTO_UDP
 119                 || proto == IPPROTO_UDPLITE
 120                 || proto == IPPROTO_SCTP || proto == IPPROTO_DCCP)
 121                 && !(ip_invflags & XT_INV_PROTO)
 122                 && (match_flags == XT_MULTIPORT_SOURCE
 123                     || match_flags == XT_MULTIPORT_DESTINATION
 124                     || match_flags == XT_MULTIPORT_EITHER)
 125                 && count <= XT_MULTI_PORTS;
 126 }
 127
 128 static int multiport_mt_check(const struct xt_mtchk_param *par)
 129 {
 130         const struct ipt_ip *ip = par->entryinfo;
 131         const struct xt_multiport_v1 *multiinfo = par->matchinfo;
 132
 133         return check(ip->proto, ip->invflags, multiinfo->flags,
 134                      multiinfo->count) ? 0 : -EINVAL;
 135 }
 136
 137 static int multiport_mt6_check(const struct xt_mtchk_param *par)
 138 {
 139         const struct ip6t_ip6 *ip = par->entryinfo;
 140         const struct xt_multiport_v1 *multiinfo = par->matchinfo;
 141
 142         return check(ip->proto, ip->invflags, multiinfo->flags,
 143                      multiinfo->count) ? 0 : -EINVAL;
 144 }
 145
 146 static struct xt_match multiport_mt_reg[] __read_mostly = {
 147         {
 148                 .name           = "multiport",
 149                 .family         = NFPROTO_IPV4,
 150                 .revision       = 1,
 151                 .checkentry     = multiport_mt_check,
 152                 .match          = multiport_mt,
 153                 .matchsize      = sizeof(struct xt_multiport_v1),
 154                 .me             = THIS_MODULE,
 155         },
 156         {
 157                 .name           = "multiport",
 158                 .family         = NFPROTO_IPV6,
 159                 .revision       = 1,
 160                 .checkentry     = multiport_mt6_check,
 161                 .match          = multiport_mt,
 162                 .matchsize      = sizeof(struct xt_multiport_v1),
 163                 .me             = THIS_MODULE,
 164         },
 165 };
 166
 167 static int __init multiport_mt_init(void)
 168 {
 169         return xt_register_matches(multiport_mt_reg,
 170                ARRAY_SIZE(multiport_mt_reg));
 171 }
 172
 173 static void __exit multiport_mt_exit(void)
 174 {
 175         xt_unregister_matches(multiport_mt_reg, ARRAY_SIZE(multiport_mt_reg));
 176 }
 177
 178 module_init(multiport_mt_init);
 179 module_exit(multiport_mt_exit);