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 /* Called when user tries to insert an entry of this type. */
 162 static bool
 163 multiport_mt_check_v0(const char *tablename, const void *info,
 164                       const struct xt_match *match, void *matchinfo,
 165                       unsigned int hook_mask)
 166 {
 167         const struct ipt_ip *ip = info;
 168         const struct xt_multiport *multiinfo = matchinfo;
 169
 170         return check(ip->proto, ip->invflags, multiinfo->flags,
 171                      multiinfo->count);
 172 }
 173
 174 static bool
 175 multiport_mt_check(const char *tablename, const void *info,
 176                    const struct xt_match *match, void *matchinfo,
 177                    unsigned int hook_mask)
 178 {
 179         const struct ipt_ip *ip = info;
 180         const struct xt_multiport_v1 *multiinfo = matchinfo;
 181
 182         return check(ip->proto, ip->invflags, multiinfo->flags,
 183                      multiinfo->count);
 184 }
 185
 186 static bool
 187 multiport_mt6_check_v0(const char *tablename, const void *info,
 188                        const struct xt_match *match, void *matchinfo,
 189                        unsigned int hook_mask)
 190 {
 191         const struct ip6t_ip6 *ip = info;
 192         const struct xt_multiport *multiinfo = matchinfo;
 193
 194         return check(ip->proto, ip->invflags, multiinfo->flags,
 195                      multiinfo->count);
 196 }
 197
 198 static bool
 199 multiport_mt6_check(const char *tablename, const void *info,
 200                     const struct xt_match *match, void *matchinfo,
 201                     unsigned int hook_mask)
 202 {
 203         const struct ip6t_ip6 *ip = info;
 204         const struct xt_multiport_v1 *multiinfo = matchinfo;
 205
 206         return check(ip->proto, ip->invflags, multiinfo->flags,
 207                      multiinfo->count);
 208 }
 209
 210 static struct xt_match multiport_mt_reg[] __read_mostly = {
 211         {
 212                 .name           = "multiport",
 213                 .family         = NFPROTO_IPV4,
 214                 .revision       = 0,
 215                 .checkentry     = multiport_mt_check_v0,
 216                 .match          = multiport_mt_v0,
 217                 .matchsize      = sizeof(struct xt_multiport),
 218                 .me             = THIS_MODULE,
 219         },
 220         {
 221                 .name           = "multiport",
 222                 .family         = NFPROTO_IPV4,
 223                 .revision       = 1,
 224                 .checkentry     = multiport_mt_check,
 225                 .match          = multiport_mt,
 226                 .matchsize      = sizeof(struct xt_multiport_v1),
 227                 .me             = THIS_MODULE,
 228         },
 229         {
 230                 .name           = "multiport",
 231                 .family         = NFPROTO_IPV6,
 232                 .revision       = 0,
 233                 .checkentry     = multiport_mt6_check_v0,
 234                 .match          = multiport_mt_v0,
 235                 .matchsize      = sizeof(struct xt_multiport),
 236                 .me             = THIS_MODULE,
 237         },
 238         {
 239                 .name           = "multiport",
 240                 .family         = NFPROTO_IPV6,
 241                 .revision       = 1,
 242                 .checkentry     = multiport_mt6_check,
 243                 .match          = multiport_mt,
 244                 .matchsize      = sizeof(struct xt_multiport_v1),
 245                 .me             = THIS_MODULE,
 246         },
 247 };
 248
 249 static int __init multiport_mt_init(void)
 250 {
 251         return xt_register_matches(multiport_mt_reg,
 252                ARRAY_SIZE(multiport_mt_reg));
 253 }
 254
 255 static void __exit multiport_mt_exit(void)
 256 {
 257         xt_unregister_matches(multiport_mt_reg, ARRAY_SIZE(multiport_mt_reg));
 258 }
 259
 260 module_init(multiport_mt_init);
 261 module_exit(multiport_mt_exit);