net/netfilter/xt_multiport.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /* Kernel module to match one of a list of TCP/UDP(-Lite)/SCTP/DCCP ports:
   3    ports are in the same place so we can treat them as equal. */
   4
   5 /* (C) 1999-2001 Paul `Rusty' Russell
   6  * (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org>
   7  */
   8 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
   9 #include <linux/module.h>
  10 #include <linux/types.h>
  11 #include <linux/udp.h>
  12 #include <linux/skbuff.h>
  13 #include <linux/in.h>
  14
  15 #include <linux/netfilter/xt_multiport.h>
  16 #include <linux/netfilter/x_tables.h>
  17 #include <linux/netfilter_ipv4/ip_tables.h>
  18 #include <linux/netfilter_ipv6/ip6_tables.h>
  19
  20 MODULE_LICENSE("GPL");
  21 MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>");
  22 MODULE_DESCRIPTION("Xtables: multiple port matching for TCP, UDP, UDP-Lite, SCTP and DCCP");
  23 MODULE_ALIAS("ipt_multiport");
  24 MODULE_ALIAS("ip6t_multiport");
  25
  26 /* Returns 1 if the port is matched by the test, 0 otherwise. */
  27 static inline bool
  28 ports_match_v1(const struct xt_multiport_v1 *minfo,
  29                u_int16_t src, u_int16_t dst)
  30 {
  31         unsigned int i;
  32         u_int16_t s, e;
  33
  34         for (i = 0; i < minfo->count; i++) {
  35                 s = minfo->ports[i];
  36
  37                 if (minfo->pflags[i]) {
  38                         /* range port matching */
  39                         e = minfo->ports[++i];
  40                         pr_debug("src or dst matches with %d-%d?\n", s, e);
  41
  42                         switch (minfo->flags) {
  43                         case XT_MULTIPORT_SOURCE:
  44                                 if (src >= s && src <= e)
  45                                         return true ^ minfo->invert;
  46                                 break;
  47                         case XT_MULTIPORT_DESTINATION:
  48                                 if (dst >= s && dst <= e)
  49                                         return true ^ minfo->invert;
  50                                 break;
  51                         case XT_MULTIPORT_EITHER:
  52                                 if ((dst >= s && dst <= e) ||
  53                                     (src >= s && src <= e))
  54                                         return true ^ minfo->invert;
  55                                 break;
  56                         default:
  57                                 break;
  58                         }
  59                 } else {
  60                         /* exact port matching */
  61                         pr_debug("src or dst matches with %d?\n", s);
  62
  63                         switch (minfo->flags) {
  64                         case XT_MULTIPORT_SOURCE:
  65                                 if (src == s)
  66                                         return true ^ minfo->invert;
  67                                 break;
  68                         case XT_MULTIPORT_DESTINATION:
  69                                 if (dst == s)
  70                                         return true ^ minfo->invert;
  71                                 break;
  72                         case XT_MULTIPORT_EITHER:
  73                                 if (src == s || dst == s)
  74                                         return true ^ minfo->invert;
  75                                 break;
  76                         default:
  77                                 break;
  78                         }
  79                 }
  80         }
  81
  82         return minfo->invert;
  83 }
  84
  85 static bool
  86 multiport_mt(const struct sk_buff *skb, struct xt_action_param *par)
  87 {
  88         const __be16 *pptr;
  89         __be16 _ports[2];
  90         const struct xt_multiport_v1 *multiinfo = par->matchinfo;
  91
  92         if (par->fragoff != 0)
  93                 return false;
  94
  95         pptr = skb_header_pointer(skb, par->thoff, sizeof(_ports), _ports);
  96         if (pptr == NULL) {
  97                 /* We've been asked to examine this packet, and we
  98                  * can't.  Hence, no choice but to drop.
  99                  */
 100                 pr_debug("Dropping evil offset=0 tinygram.\n");
 101                 par->hotdrop = true;
 102                 return false;
 103         }
 104
 105         return ports_match_v1(multiinfo, ntohs(pptr[0]), ntohs(pptr[1]));
 106 }
 107
 108 static inline bool
 109 check(u_int16_t proto,
 110       u_int8_t ip_invflags,
 111       u_int8_t match_flags,
 112       u_int8_t count)
 113 {
 114         /* Must specify supported protocol, no unknown flags or bad count */
 115         return (proto == IPPROTO_TCP || proto == IPPROTO_UDP
 116                 || proto == IPPROTO_UDPLITE
 117                 || proto == IPPROTO_SCTP || proto == IPPROTO_DCCP)
 118                 && !(ip_invflags & XT_INV_PROTO)
 119                 && (match_flags == XT_MULTIPORT_SOURCE
 120                     || match_flags == XT_MULTIPORT_DESTINATION
 121                     || match_flags == XT_MULTIPORT_EITHER)
 122                 && count <= XT_MULTI_PORTS;
 123 }
 124
 125 static int multiport_mt_check(const struct xt_mtchk_param *par)
 126 {
 127         const struct ipt_ip *ip = par->entryinfo;
 128         const struct xt_multiport_v1 *multiinfo = par->matchinfo;
 129
 130         return check(ip->proto, ip->invflags, multiinfo->flags,
 131                      multiinfo->count) ? 0 : -EINVAL;
 132 }
 133
 134 static int multiport_mt6_check(const struct xt_mtchk_param *par)
 135 {
 136         const struct ip6t_ip6 *ip = par->entryinfo;
 137         const struct xt_multiport_v1 *multiinfo = par->matchinfo;
 138
 139         return check(ip->proto, ip->invflags, multiinfo->flags,
 140                      multiinfo->count) ? 0 : -EINVAL;
 141 }
 142
 143 static struct xt_match multiport_mt_reg[] __read_mostly = {
 144         {
 145                 .name           = "multiport",
 146                 .family         = NFPROTO_IPV4,
 147                 .revision       = 1,
 148                 .checkentry     = multiport_mt_check,
 149                 .match          = multiport_mt,
 150                 .matchsize      = sizeof(struct xt_multiport_v1),
 151                 .me             = THIS_MODULE,
 152         },
 153         {
 154                 .name           = "multiport",
 155                 .family         = NFPROTO_IPV6,
 156                 .revision       = 1,
 157                 .checkentry     = multiport_mt6_check,
 158                 .match          = multiport_mt,
 159                 .matchsize      = sizeof(struct xt_multiport_v1),
 160                 .me             = THIS_MODULE,
 161         },
 162 };
 163
 164 static int __init multiport_mt_init(void)
 165 {
 166         return xt_register_matches(multiport_mt_reg,
 167                ARRAY_SIZE(multiport_mt_reg));
 168 }
 169
 170 static void __exit multiport_mt_exit(void)
 171 {
 172         xt_unregister_matches(multiport_mt_reg, ARRAY_SIZE(multiport_mt_reg));
 173 }
 174
 175 module_init(multiport_mt_init);
 176 module_exit(multiport_mt_exit);