net/netfilter/xt_multiport.c

   1 /* Kernel module to match one of a list of TCP/UDP ports: ports are in
   2    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("x_tables multiple port match module");
  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 int
  37 ports_match(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 1;
  44
  45                 if (flags != XT_MULTIPORT_SOURCE && portlist[i] == dst)
  46                         return 1;
  47         }
  48
  49         return 0;
  50 }
  51
  52 /* Returns 1 if the port is matched by the test, 0 otherwise. */
  53 static inline int
  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 1 ^ minfo->invert;
  71                         if (minfo->flags == XT_MULTIPORT_DESTINATION
  72                             && dst >= s && dst <= e)
  73                                 return 1 ^ minfo->invert;
  74                         if (minfo->flags == XT_MULTIPORT_EITHER
  75                             && ((dst >= s && dst <= e)
  76                                 || (src >= s && src <= e)))
  77                                 return 1 ^ 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 1 ^ minfo->invert;
  85                         if (minfo->flags == XT_MULTIPORT_DESTINATION
  86                             && dst == s)
  87                                 return 1 ^ minfo->invert;
  88                         if (minfo->flags == XT_MULTIPORT_EITHER
  89                             && (src == s || dst == s))
  90                                 return 1 ^ minfo->invert;
  91                 }
  92         }
  93
  94         return minfo->invert;
  95 }
  96
  97 static int
  98 match(const struct sk_buff *skb,
  99       const struct net_device *in,
 100       const struct net_device *out,
 101       const struct xt_match *match,
 102       const void *matchinfo,
 103       int offset,
 104       unsigned int protoff,
 105       int *hotdrop)
 106 {
 107         u16 _ports[2], *pptr;
 108         const struct xt_multiport *multiinfo = matchinfo;
 109
 110         if (offset)
 111                 return 0;
 112
 113         pptr = skb_header_pointer(skb, protoff, sizeof(_ports), _ports);
 114         if (pptr == NULL) {
 115                 /* We've been asked to examine this packet, and we
 116                  * can't.  Hence, no choice but to drop.
 117                  */
 118                 duprintf("xt_multiport: Dropping evil offset=0 tinygram.\n");
 119                 *hotdrop = 1;
 120                 return 0;
 121         }
 122
 123         return ports_match(multiinfo->ports,
 124                            multiinfo->flags, multiinfo->count,
 125                            ntohs(pptr[0]), ntohs(pptr[1]));
 126 }
 127
 128 static int
 129 match_v1(const struct sk_buff *skb,
 130          const struct net_device *in,
 131          const struct net_device *out,
 132          const struct xt_match *match,
 133          const void *matchinfo,
 134          int offset,
 135          unsigned int protoff,
 136          int *hotdrop)
 137 {
 138         u16 _ports[2], *pptr;
 139         const struct xt_multiport_v1 *multiinfo = matchinfo;
 140
 141         if (offset)
 142                 return 0;
 143
 144         pptr = skb_header_pointer(skb, protoff, sizeof(_ports), _ports);
 145         if (pptr == NULL) {
 146                 /* We've been asked to examine this packet, and we
 147                  * can't.  Hence, no choice but to drop.
 148                  */
 149                 duprintf("xt_multiport: Dropping evil offset=0 tinygram.\n");
 150                 *hotdrop = 1;
 151                 return 0;
 152         }
 153
 154         return ports_match_v1(multiinfo, ntohs(pptr[0]), ntohs(pptr[1]));
 155 }
 156
 157 static inline int
 158 check(u_int16_t proto,
 159       u_int8_t ip_invflags,
 160       u_int8_t match_flags,
 161       u_int8_t count)
 162 {
 163         /* Must specify proto == TCP/UDP, no unknown flags or bad count */
 164         return (proto == IPPROTO_TCP || proto == IPPROTO_UDP)
 165                 && !(ip_invflags & XT_INV_PROTO)
 166                 && (match_flags == XT_MULTIPORT_SOURCE
 167                     || match_flags == XT_MULTIPORT_DESTINATION
 168                     || match_flags == XT_MULTIPORT_EITHER)
 169                 && count <= XT_MULTI_PORTS;
 170 }
 171
 172 /* Called when user tries to insert an entry of this type. */
 173 static int
 174 checkentry(const char *tablename,
 175            const void *info,
 176            const struct xt_match *match,
 177            void *matchinfo,
 178            unsigned int matchsize,
 179            unsigned int hook_mask)
 180 {
 181         const struct ipt_ip *ip = info;
 182         const struct xt_multiport *multiinfo = matchinfo;
 183
 184         return check(ip->proto, ip->invflags, multiinfo->flags,
 185                      multiinfo->count);
 186 }
 187
 188 static int
 189 checkentry_v1(const char *tablename,
 190               const void *info,
 191               const struct xt_match *match,
 192               void *matchinfo,
 193               unsigned int matchsize,
 194               unsigned int hook_mask)
 195 {
 196         const struct ipt_ip *ip = info;
 197         const struct xt_multiport_v1 *multiinfo = matchinfo;
 198
 199         return check(ip->proto, ip->invflags, multiinfo->flags,
 200                      multiinfo->count);
 201 }
 202
 203 static int
 204 checkentry6(const char *tablename,
 205             const void *info,
 206             const struct xt_match *match,
 207             void *matchinfo,
 208             unsigned int matchsize,
 209             unsigned int hook_mask)
 210 {
 211         const struct ip6t_ip6 *ip = info;
 212         const struct xt_multiport *multiinfo = matchinfo;
 213
 214         return check(ip->proto, ip->invflags, multiinfo->flags,
 215                      multiinfo->count);
 216 }
 217
 218 static int
 219 checkentry6_v1(const char *tablename,
 220                const void *info,
 221                const struct xt_match *match,
 222                void *matchinfo,
 223                unsigned int matchsize,
 224                unsigned int hook_mask)
 225 {
 226         const struct ip6t_ip6 *ip = info;
 227         const struct xt_multiport_v1 *multiinfo = matchinfo;
 228
 229         return check(ip->proto, ip->invflags, multiinfo->flags,
 230                      multiinfo->count);
 231 }
 232
 233 static struct xt_match multiport_match = {
 234         .name           = "multiport",
 235         .revision       = 0,
 236         .matchsize      = sizeof(struct xt_multiport),
 237         .match          = &match,
 238         .checkentry     = &checkentry,
 239         .family         = AF_INET,
 240         .me             = THIS_MODULE,
 241 };
 242
 243 static struct xt_match multiport_match_v1 = {
 244         .name           = "multiport",
 245         .revision       = 1,
 246         .matchsize      = sizeof(struct xt_multiport_v1),
 247         .match          = &match_v1,
 248         .checkentry     = &checkentry_v1,
 249         .family         = AF_INET,
 250         .me             = THIS_MODULE,
 251 };
 252
 253 static struct xt_match multiport6_match = {
 254         .name           = "multiport",
 255         .revision       = 0,
 256         .matchsize      = sizeof(struct xt_multiport),
 257         .match          = &match,
 258         .checkentry     = &checkentry6,
 259         .family         = AF_INET6,
 260         .me             = THIS_MODULE,
 261 };
 262
 263 static struct xt_match multiport6_match_v1 = {
 264         .name           = "multiport",
 265         .revision       = 1,
 266         .matchsize      = sizeof(struct xt_multiport_v1),
 267         .match          = &match_v1,
 268         .checkentry     = &checkentry6_v1,
 269         .family         = AF_INET6,
 270         .me             = THIS_MODULE,
 271 };
 272
 273 static int __init xt_multiport_init(void)
 274 {
 275         int ret;
 276
 277         ret = xt_register_match(&multiport_match);
 278         if (ret)
 279                 goto out;
 280
 281         ret = xt_register_match(&multiport_match_v1);
 282         if (ret)
 283                 goto out_unreg_multi_v0;
 284
 285         ret = xt_register_match(&multiport6_match);
 286         if (ret)
 287                 goto out_unreg_multi_v1;
 288
 289         ret = xt_register_match(&multiport6_match_v1);
 290         if (ret)
 291                 goto out_unreg_multi6_v0;
 292
 293         return ret;
 294
 295 out_unreg_multi6_v0:
 296         xt_unregister_match(&multiport6_match);
 297 out_unreg_multi_v1:
 298         xt_unregister_match(&multiport_match_v1);
 299 out_unreg_multi_v0:
 300         xt_unregister_match(&multiport_match);
 301 out:
 302         return ret;
 303 }
 304
 305 static void __exit xt_multiport_fini(void)
 306 {
 307         xt_unregister_match(&multiport_match);
 308         xt_unregister_match(&multiport_match_v1);
 309         xt_unregister_match(&multiport6_match);
 310         xt_unregister_match(&multiport6_match_v1);
 311 }
 312
 313 module_init(xt_multiport_init);
 314 module_exit(xt_multiport_fini);