1 /* Kernel module to match FRAG parameters. */
3 /* (C) 2001-2002 Andras Kis-Szabo <kisza@sch.bme.hu>
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License version 2 as
7 * published by the Free Software Foundation.
10 #include <linux/module.h>
11 #include <linux/skbuff.h>
12 #include <linux/ipv6.h>
13 #include <linux/types.h>
14 #include <net/checksum.h>
17 #include <linux/netfilter/x_tables.h>
18 #include <linux/netfilter_ipv6/ip6_tables.h>
19 #include <linux/netfilter_ipv6/ip6t_frag.h>
21 MODULE_LICENSE("GPL");
22 MODULE_DESCRIPTION("IPv6 FRAG match");
23 MODULE_AUTHOR("Andras Kis-Szabo <kisza@sch.bme.hu>");
28 #define DEBUGP(format, args...)
31 /* Returns 1 if the id is matched by the range, 0 otherwise */
33 id_match(u_int32_t min, u_int32_t max, u_int32_t id, bool invert)
36 DEBUGP("frag id_match:%c 0x%x <= 0x%x <= 0x%x", invert ? '!' : ' ',
38 r = (id >= min && id <= max) ^ invert;
39 DEBUGP(" result %s\n", r ? "PASS" : "FAILED");
44 match(const struct sk_buff *skb,
45 const struct net_device *in,
46 const struct net_device *out,
47 const struct xt_match *match,
48 const void *matchinfo,
53 struct frag_hdr _frag;
54 const struct frag_hdr *fh;
55 const struct ip6t_frag *fraginfo = matchinfo;
59 err = ipv6_find_hdr(skb, &ptr, NEXTHDR_FRAGMENT, NULL);
66 fh = skb_header_pointer(skb, ptr, sizeof(_frag), &_frag);
72 DEBUGP("INFO %04X ", fh->frag_off);
73 DEBUGP("OFFSET %04X ", ntohs(fh->frag_off) & ~0x7);
74 DEBUGP("RES %02X %04X", fh->reserved, ntohs(fh->frag_off) & 0x6);
75 DEBUGP("MF %04X ", fh->frag_off & htons(IP6_MF));
76 DEBUGP("ID %u %08X\n", ntohl(fh->identification),
77 ntohl(fh->identification));
79 DEBUGP("IPv6 FRAG id %02X ",
80 id_match(fraginfo->ids[0], fraginfo->ids[1],
81 ntohl(fh->identification),
82 !!(fraginfo->invflags & IP6T_FRAG_INV_IDS)));
83 DEBUGP("res %02X %02X%04X %02X ",
84 fraginfo->flags & IP6T_FRAG_RES, fh->reserved,
85 ntohs(fh->frag_off) & 0x6,
86 !((fraginfo->flags & IP6T_FRAG_RES)
87 && (fh->reserved || (ntohs(fh->frag_off) & 0x06))));
88 DEBUGP("first %02X %02X %02X ",
89 fraginfo->flags & IP6T_FRAG_FST,
90 ntohs(fh->frag_off) & ~0x7,
91 !((fraginfo->flags & IP6T_FRAG_FST)
92 && (ntohs(fh->frag_off) & ~0x7)));
93 DEBUGP("mf %02X %02X %02X ",
94 fraginfo->flags & IP6T_FRAG_MF,
95 ntohs(fh->frag_off) & IP6_MF,
96 !((fraginfo->flags & IP6T_FRAG_MF)
97 && !((ntohs(fh->frag_off) & IP6_MF))));
98 DEBUGP("last %02X %02X %02X\n",
99 fraginfo->flags & IP6T_FRAG_NMF,
100 ntohs(fh->frag_off) & IP6_MF,
101 !((fraginfo->flags & IP6T_FRAG_NMF)
102 && (ntohs(fh->frag_off) & IP6_MF)));
106 id_match(fraginfo->ids[0], fraginfo->ids[1],
107 ntohl(fh->identification),
108 !!(fraginfo->invflags & IP6T_FRAG_INV_IDS))
110 !((fraginfo->flags & IP6T_FRAG_RES)
111 && (fh->reserved || (ntohs(fh->frag_off) & 0x6)))
113 !((fraginfo->flags & IP6T_FRAG_FST)
114 && (ntohs(fh->frag_off) & ~0x7))
116 !((fraginfo->flags & IP6T_FRAG_MF)
117 && !(ntohs(fh->frag_off) & IP6_MF))
119 !((fraginfo->flags & IP6T_FRAG_NMF)
120 && (ntohs(fh->frag_off) & IP6_MF));
123 /* Called when user tries to insert an entry of this type. */
125 checkentry(const char *tablename,
127 const struct xt_match *match,
129 unsigned int hook_mask)
131 const struct ip6t_frag *fraginfo = matchinfo;
133 if (fraginfo->invflags & ~IP6T_FRAG_INV_MASK) {
134 DEBUGP("ip6t_frag: unknown flags %X\n", fraginfo->invflags);
140 static struct xt_match frag_match = {
144 .matchsize = sizeof(struct ip6t_frag),
145 .checkentry = checkentry,
149 static int __init ip6t_frag_init(void)
151 return xt_register_match(&frag_match);
154 static void __exit ip6t_frag_fini(void)
156 xt_unregister_match(&frag_match);
159 module_init(ip6t_frag_init);
160 module_exit(ip6t_frag_fini);