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Linux/net/netfilter/xt_multiport.c

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  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);
177 

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