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Linux/net/netfilter/xt_multiport.c

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  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_v1(const struct xt_multiport_v1 *minfo,
 32                u_int16_t src, u_int16_t dst)
 33 {
 34         unsigned int i;
 35         u_int16_t s, e;
 36 
 37         for (i = 0; i < minfo->count; i++) {
 38                 s = minfo->ports[i];
 39 
 40                 if (minfo->pflags[i]) {
 41                         /* range port matching */
 42                         e = minfo->ports[++i];
 43                         pr_debug("src or dst matches with %d-%d?\n", s, e);
 44 
 45                         switch (minfo->flags) {
 46                         case XT_MULTIPORT_SOURCE:
 47                                 if (src >= s && src <= e)
 48                                         return true ^ minfo->invert;
 49                                 break;
 50                         case XT_MULTIPORT_DESTINATION:
 51                                 if (dst >= s && dst <= e)
 52                                         return true ^ minfo->invert;
 53                                 break;
 54                         case XT_MULTIPORT_EITHER:
 55                                 if ((dst >= s && dst <= e) ||
 56                                     (src >= s && src <= e))
 57                                         return true ^ minfo->invert;
 58                                 break;
 59                         default:
 60                                 break;
 61                         }
 62                 } else {
 63                         /* exact port matching */
 64                         pr_debug("src or dst matches with %d?\n", s);
 65 
 66                         switch (minfo->flags) {
 67                         case XT_MULTIPORT_SOURCE:
 68                                 if (src == s)
 69                                         return true ^ minfo->invert;
 70                                 break;
 71                         case XT_MULTIPORT_DESTINATION:
 72                                 if (dst == s)
 73                                         return true ^ minfo->invert;
 74                                 break;
 75                         case XT_MULTIPORT_EITHER:
 76                                 if (src == s || dst == s)
 77                                         return true ^ minfo->invert;
 78                                 break;
 79                         default:
 80                                 break;
 81                         }
 82                 }
 83         }
 84 
 85         return minfo->invert;
 86 }
 87 
 88 static bool
 89 multiport_mt(const struct sk_buff *skb, struct xt_action_param *par)
 90 {
 91         const __be16 *pptr;
 92         __be16 _ports[2];
 93         const struct xt_multiport_v1 *multiinfo = par->matchinfo;
 94 
 95         if (par->fragoff != 0)
 96                 return false;
 97 
 98         pptr = skb_header_pointer(skb, par->thoff, sizeof(_ports), _ports);
 99         if (pptr == NULL) {
100                 /* We've been asked to examine this packet, and we
101                  * can't.  Hence, no choice but to drop.
102                  */
103                 pr_debug("Dropping evil offset=0 tinygram.\n");
104                 par->hotdrop = true;
105                 return false;
106         }
107 
108         return ports_match_v1(multiinfo, ntohs(pptr[0]), ntohs(pptr[1]));
109 }
110 
111 static inline bool
112 check(u_int16_t proto,
113       u_int8_t ip_invflags,
114       u_int8_t match_flags,
115       u_int8_t count)
116 {
117         /* Must specify supported protocol, no unknown flags or bad count */
118         return (proto == IPPROTO_TCP || proto == IPPROTO_UDP
119                 || proto == IPPROTO_UDPLITE
120                 || proto == IPPROTO_SCTP || proto == IPPROTO_DCCP)
121                 && !(ip_invflags & XT_INV_PROTO)
122                 && (match_flags == XT_MULTIPORT_SOURCE
123                     || match_flags == XT_MULTIPORT_DESTINATION
124                     || match_flags == XT_MULTIPORT_EITHER)
125                 && count <= XT_MULTI_PORTS;
126 }
127 
128 static int multiport_mt_check(const struct xt_mtchk_param *par)
129 {
130         const struct ipt_ip *ip = par->entryinfo;
131         const struct xt_multiport_v1 *multiinfo = par->matchinfo;
132 
133         return check(ip->proto, ip->invflags, multiinfo->flags,
134                      multiinfo->count) ? 0 : -EINVAL;
135 }
136 
137 static int multiport_mt6_check(const struct xt_mtchk_param *par)
138 {
139         const struct ip6t_ip6 *ip = par->entryinfo;
140         const struct xt_multiport_v1 *multiinfo = par->matchinfo;
141 
142         return check(ip->proto, ip->invflags, multiinfo->flags,
143                      multiinfo->count) ? 0 : -EINVAL;
144 }
145 
146 static struct xt_match multiport_mt_reg[] __read_mostly = {
147         {
148                 .name           = "multiport",
149                 .family         = NFPROTO_IPV4,
150                 .revision       = 1,
151                 .checkentry     = multiport_mt_check,
152                 .match          = multiport_mt,
153                 .matchsize      = sizeof(struct xt_multiport_v1),
154                 .me             = THIS_MODULE,
155         },
156         {
157                 .name           = "multiport",
158                 .family         = NFPROTO_IPV6,
159                 .revision       = 1,
160                 .checkentry     = multiport_mt6_check,
161                 .match          = multiport_mt,
162                 .matchsize      = sizeof(struct xt_multiport_v1),
163                 .me             = THIS_MODULE,
164         },
165 };
166 
167 static int __init multiport_mt_init(void)
168 {
169         return xt_register_matches(multiport_mt_reg,
170                ARRAY_SIZE(multiport_mt_reg));
171 }
172 
173 static void __exit multiport_mt_exit(void)
174 {
175         xt_unregister_matches(multiport_mt_reg, ARRAY_SIZE(multiport_mt_reg));
176 }
177 
178 module_init(multiport_mt_init);
179 module_exit(multiport_mt_exit);
180 

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