Commit | Line | Data |
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1da177e4 LT |
1 | /* Kernel module to match Hop-by-Hop and Destination parameters. */ |
2 | ||
3 | /* (C) 2001-2002 Andras Kis-Szabo <kisza@sch.bme.hu> | |
4 | * | |
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. | |
8 | */ | |
9 | ||
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> | |
15 | #include <net/ipv6.h> | |
16 | ||
17 | #include <asm/byteorder.h> | |
18 | ||
19 | #include <linux/netfilter_ipv6/ip6_tables.h> | |
20 | #include <linux/netfilter_ipv6/ip6t_opts.h> | |
21 | ||
22 | #define HOPBYHOP 1 | |
23 | ||
24 | MODULE_LICENSE("GPL"); | |
25 | #if HOPBYHOP | |
26 | MODULE_DESCRIPTION("IPv6 HbH match"); | |
27 | #else | |
28 | MODULE_DESCRIPTION("IPv6 DST match"); | |
29 | #endif | |
30 | MODULE_AUTHOR("Andras Kis-Szabo <kisza@sch.bme.hu>"); | |
31 | ||
32 | #if 0 | |
33 | #define DEBUGP printk | |
34 | #else | |
35 | #define DEBUGP(format, args...) | |
36 | #endif | |
37 | ||
38 | /* | |
f0daaa65 YK |
39 | * (Type & 0xC0) >> 6 |
40 | * 0 -> ignorable | |
41 | * 1 -> must drop the packet | |
42 | * 2 -> send ICMP PARM PROB regardless and drop packet | |
43 | * 3 -> Send ICMP if not a multicast address and drop packet | |
1da177e4 | 44 | * (Type & 0x20) >> 5 |
f0daaa65 YK |
45 | * 0 -> invariant |
46 | * 1 -> can change the routing | |
1da177e4 | 47 | * (Type & 0x1F) Type |
f0daaa65 YK |
48 | * 0 -> Pad1 (only 1 byte!) |
49 | * 1 -> PadN LENGTH info (total length = length + 2) | |
50 | * C0 | 2 -> JUMBO 4 x x x x ( xxxx > 64k ) | |
51 | * 5 -> RTALERT 2 x x | |
1da177e4 LT |
52 | */ |
53 | ||
54 | static int | |
55 | match(const struct sk_buff *skb, | |
56 | const struct net_device *in, | |
57 | const struct net_device *out, | |
c4986734 | 58 | const struct xt_match *match, |
1da177e4 LT |
59 | const void *matchinfo, |
60 | int offset, | |
61 | unsigned int protoff, | |
62 | int *hotdrop) | |
63 | { | |
f0daaa65 YK |
64 | struct ipv6_opt_hdr _optsh, *oh; |
65 | const struct ip6t_opts *optinfo = matchinfo; | |
66 | unsigned int temp; | |
67 | unsigned int ptr; | |
68 | unsigned int hdrlen = 0; | |
69 | unsigned int ret = 0; | |
70 | u8 _opttype, *tp = NULL; | |
71 | u8 _optlen, *lp = NULL; | |
72 | unsigned int optlen; | |
73 | ||
1da177e4 | 74 | #if HOPBYHOP |
b777e0ce | 75 | if (ipv6_find_hdr(skb, &ptr, NEXTHDR_HOP, NULL) < 0) |
1da177e4 | 76 | #else |
b777e0ce | 77 | if (ipv6_find_hdr(skb, &ptr, NEXTHDR_DEST, NULL) < 0) |
1da177e4 | 78 | #endif |
e674d0f3 | 79 | return 0; |
1da177e4 | 80 | |
f0daaa65 YK |
81 | oh = skb_header_pointer(skb, ptr, sizeof(_optsh), &_optsh); |
82 | if (oh == NULL) { | |
83 | *hotdrop = 1; | |
84 | return 0; | |
85 | } | |
86 | ||
87 | hdrlen = ipv6_optlen(oh); | |
88 | if (skb->len - ptr < hdrlen) { | |
89 | /* Packet smaller than it's length field */ | |
90 | return 0; | |
91 | } | |
92 | ||
93 | DEBUGP("IPv6 OPTS LEN %u %u ", hdrlen, oh->hdrlen); | |
94 | ||
95 | DEBUGP("len %02X %04X %02X ", | |
96 | optinfo->hdrlen, hdrlen, | |
97 | (!(optinfo->flags & IP6T_OPTS_LEN) || | |
98 | ((optinfo->hdrlen == hdrlen) ^ | |
99 | !!(optinfo->invflags & IP6T_OPTS_INV_LEN)))); | |
100 | ||
101 | ret = (oh != NULL) && | |
102 | (!(optinfo->flags & IP6T_OPTS_LEN) || | |
103 | ((optinfo->hdrlen == hdrlen) ^ | |
104 | !!(optinfo->invflags & IP6T_OPTS_INV_LEN))); | |
105 | ||
106 | ptr += 2; | |
107 | hdrlen -= 2; | |
108 | if (!(optinfo->flags & IP6T_OPTS_OPTS)) { | |
109 | return ret; | |
1da177e4 LT |
110 | } else if (optinfo->flags & IP6T_OPTS_NSTRICT) { |
111 | DEBUGP("Not strict - not implemented"); | |
112 | } else { | |
113 | DEBUGP("Strict "); | |
f0daaa65 YK |
114 | DEBUGP("#%d ", optinfo->optsnr); |
115 | for (temp = 0; temp < optinfo->optsnr; temp++) { | |
1da177e4 LT |
116 | /* type field exists ? */ |
117 | if (hdrlen < 1) | |
118 | break; | |
119 | tp = skb_header_pointer(skb, ptr, sizeof(_opttype), | |
120 | &_opttype); | |
121 | if (tp == NULL) | |
122 | break; | |
123 | ||
124 | /* Type check */ | |
f0daaa65 | 125 | if (*tp != (optinfo->opts[temp] & 0xFF00) >> 8) { |
1da177e4 LT |
126 | DEBUGP("Tbad %02X %02X\n", |
127 | *tp, | |
f0daaa65 | 128 | (optinfo->opts[temp] & 0xFF00) >> 8); |
1da177e4 LT |
129 | return 0; |
130 | } else { | |
131 | DEBUGP("Tok "); | |
132 | } | |
133 | /* Length check */ | |
134 | if (*tp) { | |
135 | u16 spec_len; | |
136 | ||
137 | /* length field exists ? */ | |
138 | if (hdrlen < 2) | |
139 | break; | |
140 | lp = skb_header_pointer(skb, ptr + 1, | |
141 | sizeof(_optlen), | |
142 | &_optlen); | |
143 | if (lp == NULL) | |
144 | break; | |
145 | spec_len = optinfo->opts[temp] & 0x00FF; | |
146 | ||
147 | if (spec_len != 0x00FF && spec_len != *lp) { | |
148 | DEBUGP("Lbad %02X %04X\n", *lp, | |
149 | spec_len); | |
150 | return 0; | |
151 | } | |
152 | DEBUGP("Lok "); | |
153 | optlen = *lp + 2; | |
154 | } else { | |
155 | DEBUGP("Pad1\n"); | |
156 | optlen = 1; | |
157 | } | |
158 | ||
159 | /* Step to the next */ | |
160 | DEBUGP("len%04X \n", optlen); | |
161 | ||
162 | if ((ptr > skb->len - optlen || hdrlen < optlen) && | |
163 | (temp < optinfo->optsnr - 1)) { | |
164 | DEBUGP("new pointer is too large! \n"); | |
165 | break; | |
166 | } | |
167 | ptr += optlen; | |
168 | hdrlen -= optlen; | |
169 | } | |
170 | if (temp == optinfo->optsnr) | |
171 | return ret; | |
f0daaa65 YK |
172 | else |
173 | return 0; | |
1da177e4 LT |
174 | } |
175 | ||
176 | return 0; | |
177 | } | |
178 | ||
179 | /* Called when user tries to insert an entry of this type. */ | |
180 | static int | |
181 | checkentry(const char *tablename, | |
f0daaa65 | 182 | const void *entry, |
c4986734 | 183 | const struct xt_match *match, |
f0daaa65 YK |
184 | void *matchinfo, |
185 | unsigned int matchinfosize, | |
186 | unsigned int hook_mask) | |
1da177e4 | 187 | { |
f0daaa65 YK |
188 | const struct ip6t_opts *optsinfo = matchinfo; |
189 | ||
f0daaa65 YK |
190 | if (optsinfo->invflags & ~IP6T_OPTS_INV_MASK) { |
191 | DEBUGP("ip6t_opts: unknown flags %X\n", optsinfo->invflags); | |
192 | return 0; | |
193 | } | |
f0daaa65 | 194 | return 1; |
1da177e4 LT |
195 | } |
196 | ||
197 | static struct ip6t_match opts_match = { | |
198 | #if HOPBYHOP | |
199 | .name = "hbh", | |
200 | #else | |
201 | .name = "dst", | |
202 | #endif | |
7f939713 PM |
203 | .match = match, |
204 | .matchsize = sizeof(struct ip6t_opts), | |
205 | .checkentry = checkentry, | |
1da177e4 LT |
206 | .me = THIS_MODULE, |
207 | }; | |
208 | ||
65b4b4e8 | 209 | static int __init ip6t_hbh_init(void) |
1da177e4 | 210 | { |
f0daaa65 | 211 | return ip6t_register_match(&opts_match); |
1da177e4 LT |
212 | } |
213 | ||
65b4b4e8 | 214 | static void __exit ip6t_hbh_fini(void) |
1da177e4 | 215 | { |
f0daaa65 | 216 | ip6t_unregister_match(&opts_match); |
1da177e4 LT |
217 | } |
218 | ||
65b4b4e8 AM |
219 | module_init(ip6t_hbh_init); |
220 | module_exit(ip6t_hbh_fini); |