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 net_device *in,
  99                 const struct net_device *out, const struct xt_match *match,
 100                 const void *matchinfo, int offset, unsigned int protoff,
 101                 bool *hotdrop)
 102 {
 103         __be16 _ports[2], *pptr;
 104         const struct xt_multiport *multiinfo = matchinfo;
 105
 106         if (offset)
 107                 return false;
 108
 109         pptr = skb_header_pointer(skb, protoff, sizeof(_ports), _ports);
 110         if (pptr == NULL) {
 111                 /* We've been asked to examine this packet, and we
 112                  * can't.  Hence, no choice but to drop.
 113                  */
 114                 duprintf("xt_multiport: Dropping evil offset=0 tinygram.\n");
 115                 *hotdrop = true;
 116                 return false;
 117         }
 118
 119         return ports_match_v0(multiinfo->ports, multiinfo->flags,
 120                multiinfo->count, ntohs(pptr[0]), ntohs(pptr[1]));
 121 }
 122
 123 static bool
 124 multiport_mt(const struct sk_buff *skb, const struct net_device *in,
 125              const struct net_device *out, const struct xt_match *match,
 126              const void *matchinfo, int offset, unsigned int protoff,
 127              bool *hotdrop)
 128 {
 129         __be16 _ports[2], *pptr;
 130         const struct xt_multiport_v1 *multiinfo = matchinfo;
 131
 132         if (offset)
 133                 return false;
 134
 135         pptr = skb_header_pointer(skb, protoff, sizeof(_ports), _ports);
 136         if (pptr == NULL) {
 137                 /* We've been asked to examine this packet, and we
 138                  * can't.  Hence, no choice but to drop.
 139                  */
 140                 duprintf("xt_multiport: Dropping evil offset=0 tinygram.\n");
 141                 *hotdrop = true;
 142                 return false;
 143         }
 144
 145         return ports_match_v1(multiinfo, ntohs(pptr[0]), ntohs(pptr[1]));
 146 }
 147
 148 static inline bool
 149 check(u_int16_t proto,
 150       u_int8_t ip_invflags,
 151       u_int8_t match_flags,
 152       u_int8_t count)
 153 {
 154         /* Must specify supported protocol, no unknown flags or bad count */
 155         return (proto == IPPROTO_TCP || proto == IPPROTO_UDP
 156                 || proto == IPPROTO_UDPLITE
 157                 || proto == IPPROTO_SCTP || proto == IPPROTO_DCCP)
 158                 && !(ip_invflags & XT_INV_PROTO)
 159                 && (match_flags == XT_MULTIPORT_SOURCE
 160                     || match_flags == XT_MULTIPORT_DESTINATION
 161                     || match_flags == XT_MULTIPORT_EITHER)
 162                 && count <= XT_MULTI_PORTS;
 163 }
 164
 165 /* Called when user tries to insert an entry of this type. */
 166 static bool
 167 multiport_mt_check_v0(const char *tablename, const void *info,
 168                       const struct xt_match *match, void *matchinfo,
 169                       unsigned int hook_mask)
 170 {
 171         const struct ipt_ip *ip = info;
 172         const struct xt_multiport *multiinfo = matchinfo;
 173
 174         return check(ip->proto, ip->invflags, multiinfo->flags,
 175                      multiinfo->count);
 176 }
 177
 178 static bool
 179 multiport_mt_check(const char *tablename, const void *info,
 180                    const struct xt_match *match, void *matchinfo,
 181                    unsigned int hook_mask)
 182 {
 183         const struct ipt_ip *ip = info;
 184         const struct xt_multiport_v1 *multiinfo = matchinfo;
 185
 186         return check(ip->proto, ip->invflags, multiinfo->flags,
 187                      multiinfo->count);
 188 }
 189
 190 static bool
 191 multiport_mt6_check_v0(const char *tablename, const void *info,
 192                        const struct xt_match *match, void *matchinfo,
 193                        unsigned int hook_mask)
 194 {
 195         const struct ip6t_ip6 *ip = info;
 196         const struct xt_multiport *multiinfo = matchinfo;
 197
 198         return check(ip->proto, ip->invflags, multiinfo->flags,
 199                      multiinfo->count);
 200 }
 201
 202 static bool
 203 multiport_mt6_check(const char *tablename, const void *info,
 204                     const struct xt_match *match, void *matchinfo,
 205                     unsigned int hook_mask)
 206 {
 207         const struct ip6t_ip6 *ip = info;
 208         const struct xt_multiport_v1 *multiinfo = matchinfo;
 209
 210         return check(ip->proto, ip->invflags, multiinfo->flags,
 211                      multiinfo->count);
 212 }
 213
 214 static struct xt_match multiport_mt_reg[] __read_mostly = {
 215         {
 216                 .name           = "multiport",
 217                 .family         = AF_INET,
 218                 .revision       = 0,
 219                 .checkentry     = multiport_mt_check_v0,
 220                 .match          = multiport_mt_v0,
 221                 .matchsize      = sizeof(struct xt_multiport),
 222                 .me             = THIS_MODULE,
 223         },
 224         {
 225                 .name           = "multiport",
 226                 .family         = AF_INET,
 227                 .revision       = 1,
 228                 .checkentry     = multiport_mt_check,
 229                 .match          = multiport_mt,
 230                 .matchsize      = sizeof(struct xt_multiport_v1),
 231                 .me             = THIS_MODULE,
 232         },
 233         {
 234                 .name           = "multiport",
 235                 .family         = AF_INET6,
 236                 .revision       = 0,
 237                 .checkentry     = multiport_mt6_check_v0,
 238                 .match          = multiport_mt_v0,
 239                 .matchsize      = sizeof(struct xt_multiport),
 240                 .me             = THIS_MODULE,
 241         },
 242         {
 243                 .name           = "multiport",
 244                 .family         = AF_INET6,
 245                 .revision       = 1,
 246                 .checkentry     = multiport_mt6_check,
 247                 .match          = multiport_mt,
 248                 .matchsize      = sizeof(struct xt_multiport_v1),
 249                 .me             = THIS_MODULE,
 250         },
 251 };
 252
 253 static int __init multiport_mt_init(void)
 254 {
 255         return xt_register_matches(multiport_mt_reg,
 256                ARRAY_SIZE(multiport_mt_reg));
 257 }
 258
 259 static void __exit multiport_mt_exit(void)
 260 {
 261         xt_unregister_matches(multiport_mt_reg, ARRAY_SIZE(multiport_mt_reg));
 262 }
 263
 264 module_init(multiport_mt_init);
 265 module_exit(multiport_mt_exit);