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