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
  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 #if 0
  30 #define duprintf(format, args...) printk(format , ## args)
  31 #else
  32 #define duprintf(format, args...)
  33 #endif
  34
  35 /* Returns 1 if the port is matched by the test, 0 otherwise. */
  36 static inline bool
  37 ports_match_v0(const u_int16_t *portlist, enum xt_multiport_flags flags,
  38                u_int8_t count, u_int16_t src, u_int16_t dst)
  39 {
  40         unsigned int i;
  41         for (i = 0; i < count; i++) {
  42                 if (flags != XT_MULTIPORT_DESTINATION && portlist[i] == src)
  43                         return true;
  44
  45                 if (flags != XT_MULTIPORT_SOURCE && portlist[i] == dst)
  46                         return true;
  47         }
  48
  49         return false;
  50 }
  51
  52 /* Returns 1 if the port is matched by the test, 0 otherwise. */
  53 static inline bool
  54 ports_match_v1(const struct xt_multiport_v1 *minfo,
  55                u_int16_t src, u_int16_t dst)
  56 {
  57         unsigned int i;
  58         u_int16_t s, e;
  59
  60         for (i = 0; i < minfo->count; i++) {
  61                 s = minfo->ports[i];
  62
  63                 if (minfo->pflags[i]) {
  64                         /* range port matching */
  65                         e = minfo->ports[++i];
  66                         duprintf("src or dst matches with %d-%d?\n", s, e);
  67
  68                         if (minfo->flags == XT_MULTIPORT_SOURCE
  69                             && src >= s && src <= e)
  70                                 return true ^ minfo->invert;
  71                         if (minfo->flags == XT_MULTIPORT_DESTINATION
  72                             && dst >= s && dst <= e)
  73                                 return true ^ minfo->invert;
  74                         if (minfo->flags == XT_MULTIPORT_EITHER
  75                             && ((dst >= s && dst <= e)
  76                                 || (src >= s && src <= e)))
  77                                 return true ^ minfo->invert;
  78                 } else {
  79                         /* exact port matching */
  80                         duprintf("src or dst matches with %d?\n", s);
  81
  82                         if (minfo->flags == XT_MULTIPORT_SOURCE
  83                             && src == s)
  84                                 return true ^ minfo->invert;
  85                         if (minfo->flags == XT_MULTIPORT_DESTINATION
  86                             && dst == s)
  87                                 return true ^ minfo->invert;
  88                         if (minfo->flags == XT_MULTIPORT_EITHER
  89                             && (src == s || dst == s))
  90                                 return true ^ minfo->invert;
  91                 }
  92         }
  93
  94         return minfo->invert;
  95 }
  96
  97 static bool
  98 multiport_mt_v0(const struct sk_buff *skb, const struct xt_match_param *par)
  99 {
 100         const __be16 *pptr;
 101         __be16 _ports[2];
 102         const struct xt_multiport *multiinfo = par->matchinfo;
 103
 104         if (par->fragoff != 0)
 105                 return false;
 106
 107         pptr = skb_header_pointer(skb, par->thoff, sizeof(_ports), _ports);
 108         if (pptr == NULL) {
 109                 /* We've been asked to examine this packet, and we
 110                  * can't.  Hence, no choice but to drop.
 111                  */
 112                 duprintf("xt_multiport: Dropping evil offset=0 tinygram.\n");
 113                 *par->hotdrop = true;
 114                 return false;
 115         }
 116
 117         return ports_match_v0(multiinfo->ports, multiinfo->flags,
 118                multiinfo->count, ntohs(pptr[0]), ntohs(pptr[1]));
 119 }
 120
 121 static bool
 122 multiport_mt(const struct sk_buff *skb, const struct xt_match_param *par)
 123 {
 124         const __be16 *pptr;
 125         __be16 _ports[2];
 126         const struct xt_multiport_v1 *multiinfo = par->matchinfo;
 127
 128         if (par->fragoff != 0)
 129                 return false;
 130
 131         pptr = skb_header_pointer(skb, par->thoff, sizeof(_ports), _ports);
 132         if (pptr == NULL) {
 133                 /* We've been asked to examine this packet, and we
 134                  * can't.  Hence, no choice but to drop.
 135                  */
 136                 duprintf("xt_multiport: Dropping evil offset=0 tinygram.\n");
 137                 *par->hotdrop = true;
 138                 return false;
 139         }
 140
 141         return ports_match_v1(multiinfo, ntohs(pptr[0]), ntohs(pptr[1]));
 142 }
 143
 144 static inline bool
 145 check(u_int16_t proto,
 146       u_int8_t ip_invflags,
 147       u_int8_t match_flags,
 148       u_int8_t count)
 149 {
 150         /* Must specify supported protocol, no unknown flags or bad count */
 151         return (proto == IPPROTO_TCP || proto == IPPROTO_UDP
 152                 || proto == IPPROTO_UDPLITE
 153                 || proto == IPPROTO_SCTP || proto == IPPROTO_DCCP)
 154                 && !(ip_invflags & XT_INV_PROTO)
 155                 && (match_flags == XT_MULTIPORT_SOURCE
 156                     || match_flags == XT_MULTIPORT_DESTINATION
 157                     || match_flags == XT_MULTIPORT_EITHER)
 158                 && count <= XT_MULTI_PORTS;
 159 }
 160
 161 static bool multiport_mt_check_v0(const struct xt_mtchk_param *par)
 162 {
 163         const struct ipt_ip *ip = par->entryinfo;
 164         const struct xt_multiport *multiinfo = par->matchinfo;
 165
 166         return check(ip->proto, ip->invflags, multiinfo->flags,
 167                      multiinfo->count);
 168 }
 169
 170 static bool multiport_mt_check(const struct xt_mtchk_param *par)
 171 {
 172         const struct ipt_ip *ip = par->entryinfo;
 173         const struct xt_multiport_v1 *multiinfo = par->matchinfo;
 174
 175         return check(ip->proto, ip->invflags, multiinfo->flags,
 176                      multiinfo->count);
 177 }
 178
 179 static bool multiport_mt6_check_v0(const struct xt_mtchk_param *par)
 180 {
 181         const struct ip6t_ip6 *ip = par->entryinfo;
 182         const struct xt_multiport *multiinfo = par->matchinfo;
 183
 184         return check(ip->proto, ip->invflags, multiinfo->flags,
 185                      multiinfo->count);
 186 }
 187
 188 static bool multiport_mt6_check(const struct xt_mtchk_param *par)
 189 {
 190         const struct ip6t_ip6 *ip = par->entryinfo;
 191         const struct xt_multiport_v1 *multiinfo = par->matchinfo;
 192
 193         return check(ip->proto, ip->invflags, multiinfo->flags,
 194                      multiinfo->count);
 195 }
 196
 197 static struct xt_match multiport_mt_reg[] __read_mostly = {
 198         {
 199                 .name           = "multiport",
 200                 .family         = NFPROTO_IPV4,
 201                 .revision       = 0,
 202                 .checkentry     = multiport_mt_check_v0,
 203                 .match          = multiport_mt_v0,
 204                 .matchsize      = sizeof(struct xt_multiport),
 205                 .me             = THIS_MODULE,
 206         },
 207         {
 208                 .name           = "multiport",
 209                 .family         = NFPROTO_IPV4,
 210                 .revision       = 1,
 211                 .checkentry     = multiport_mt_check,
 212                 .match          = multiport_mt,
 213                 .matchsize      = sizeof(struct xt_multiport_v1),
 214                 .me             = THIS_MODULE,
 215         },
 216         {
 217                 .name           = "multiport",
 218                 .family         = NFPROTO_IPV6,
 219                 .revision       = 0,
 220                 .checkentry     = multiport_mt6_check_v0,
 221                 .match          = multiport_mt_v0,
 222                 .matchsize      = sizeof(struct xt_multiport),
 223                 .me             = THIS_MODULE,
 224         },
 225         {
 226                 .name           = "multiport",
 227                 .family         = NFPROTO_IPV6,
 228                 .revision       = 1,
 229                 .checkentry     = multiport_mt6_check,
 230                 .match          = multiport_mt,
 231                 .matchsize      = sizeof(struct xt_multiport_v1),
 232                 .me             = THIS_MODULE,
 233         },
 234 };
 235
 236 static int __init multiport_mt_init(void)
 237 {
 238         return xt_register_matches(multiport_mt_reg,
 239                ARRAY_SIZE(multiport_mt_reg));
 240 }
 241
 242 static void __exit multiport_mt_exit(void)
 243 {
 244         xt_unregister_matches(multiport_mt_reg, ARRAY_SIZE(multiport_mt_reg));
 245 }
 246
 247 module_init(multiport_mt_init);
 248 module_exit(multiport_mt_exit);