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