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#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
  23MODULE_LICENSE("GPL");
  24MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>");
  25MODULE_DESCRIPTION("Xtables: multiple port matching for TCP, UDP, UDP-Lite, SCTP and DCCP");
  26MODULE_ALIAS("ipt_multiport");
  27MODULE_ALIAS("ip6t_multiport");
  28
  29/* Returns 1 if the port is matched by the test, 0 otherwise. */
  30static inline bool
  31ports_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
  74static bool
  75multiport_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
  97static inline bool
  98check(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
 114static 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
 123static 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
 132static 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
 153static int __init multiport_mt_init(void)
 154{
 155        return xt_register_matches(multiport_mt_reg,
 156               ARRAY_SIZE(multiport_mt_reg));
 157}
 158
 159static void __exit multiport_mt_exit(void)
 160{
 161        xt_unregister_matches(multiport_mt_reg, ARRAY_SIZE(multiport_mt_reg));
 162}
 163
 164module_init(multiport_mt_init);
 165module_exit(multiport_mt_exit);
 166
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