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 | ||
6709dbbb | 19 | #include <linux/netfilter/x_tables.h> |
1da177e4 LT |
20 | #include <linux/netfilter_ipv6/ip6_tables.h> |
21 | #include <linux/netfilter_ipv6/ip6t_opts.h> | |
22 | ||
1da177e4 | 23 | MODULE_LICENSE("GPL"); |
2ae15b64 | 24 | MODULE_DESCRIPTION("Xtables: IPv6 Hop-By-Hop and Destination Header match"); |
1da177e4 | 25 | MODULE_AUTHOR("Andras Kis-Szabo <kisza@sch.bme.hu>"); |
5fa2a760 | 26 | MODULE_ALIAS("ip6t_dst"); |
1da177e4 | 27 | |
1da177e4 | 28 | /* |
f0daaa65 YK |
29 | * (Type & 0xC0) >> 6 |
30 | * 0 -> ignorable | |
31 | * 1 -> must drop the packet | |
32 | * 2 -> send ICMP PARM PROB regardless and drop packet | |
33 | * 3 -> Send ICMP if not a multicast address and drop packet | |
1da177e4 | 34 | * (Type & 0x20) >> 5 |
f0daaa65 YK |
35 | * 0 -> invariant |
36 | * 1 -> can change the routing | |
1da177e4 | 37 | * (Type & 0x1F) Type |
f0daaa65 YK |
38 | * 0 -> Pad1 (only 1 byte!) |
39 | * 1 -> PadN LENGTH info (total length = length + 2) | |
40 | * C0 | 2 -> JUMBO 4 x x x x ( xxxx > 64k ) | |
41 | * 5 -> RTALERT 2 x x | |
1da177e4 LT |
42 | */ |
43 | ||
1d93a9cb | 44 | static bool |
f7108a20 | 45 | hbh_mt6(const struct sk_buff *skb, const struct xt_match_param *par) |
1da177e4 | 46 | { |
a47362a2 JE |
47 | struct ipv6_opt_hdr _optsh; |
48 | const struct ipv6_opt_hdr *oh; | |
f7108a20 | 49 | const struct ip6t_opts *optinfo = par->matchinfo; |
f0daaa65 YK |
50 | unsigned int temp; |
51 | unsigned int ptr; | |
52 | unsigned int hdrlen = 0; | |
1d93a9cb | 53 | bool ret = false; |
a47362a2 JE |
54 | u8 _opttype; |
55 | u8 _optlen; | |
56 | const u_int8_t *tp = NULL; | |
57 | const u_int8_t *lp = NULL; | |
f0daaa65 | 58 | unsigned int optlen; |
6d381634 | 59 | int err; |
f0daaa65 | 60 | |
f7108a20 | 61 | err = ipv6_find_hdr(skb, &ptr, par->match->data, NULL); |
6d381634 PM |
62 | if (err < 0) { |
63 | if (err != -ENOENT) | |
f7108a20 | 64 | *par->hotdrop = true; |
1d93a9cb | 65 | return false; |
6d381634 | 66 | } |
1da177e4 | 67 | |
f0daaa65 YK |
68 | oh = skb_header_pointer(skb, ptr, sizeof(_optsh), &_optsh); |
69 | if (oh == NULL) { | |
f7108a20 | 70 | *par->hotdrop = true; |
1d93a9cb | 71 | return false; |
f0daaa65 YK |
72 | } |
73 | ||
74 | hdrlen = ipv6_optlen(oh); | |
75 | if (skb->len - ptr < hdrlen) { | |
76 | /* Packet smaller than it's length field */ | |
1d93a9cb | 77 | return false; |
f0daaa65 YK |
78 | } |
79 | ||
0d53778e | 80 | pr_debug("IPv6 OPTS LEN %u %u ", hdrlen, oh->hdrlen); |
f0daaa65 | 81 | |
0d53778e PM |
82 | pr_debug("len %02X %04X %02X ", |
83 | optinfo->hdrlen, hdrlen, | |
84 | (!(optinfo->flags & IP6T_OPTS_LEN) || | |
85 | ((optinfo->hdrlen == hdrlen) ^ | |
86 | !!(optinfo->invflags & IP6T_OPTS_INV_LEN)))); | |
f0daaa65 YK |
87 | |
88 | ret = (oh != NULL) && | |
89 | (!(optinfo->flags & IP6T_OPTS_LEN) || | |
90 | ((optinfo->hdrlen == hdrlen) ^ | |
91 | !!(optinfo->invflags & IP6T_OPTS_INV_LEN))); | |
92 | ||
93 | ptr += 2; | |
94 | hdrlen -= 2; | |
95 | if (!(optinfo->flags & IP6T_OPTS_OPTS)) { | |
96 | return ret; | |
1da177e4 | 97 | } else { |
0d53778e PM |
98 | pr_debug("Strict "); |
99 | pr_debug("#%d ", optinfo->optsnr); | |
f0daaa65 | 100 | for (temp = 0; temp < optinfo->optsnr; temp++) { |
1da177e4 LT |
101 | /* type field exists ? */ |
102 | if (hdrlen < 1) | |
103 | break; | |
104 | tp = skb_header_pointer(skb, ptr, sizeof(_opttype), | |
105 | &_opttype); | |
106 | if (tp == NULL) | |
107 | break; | |
108 | ||
109 | /* Type check */ | |
f0daaa65 | 110 | if (*tp != (optinfo->opts[temp] & 0xFF00) >> 8) { |
0d53778e PM |
111 | pr_debug("Tbad %02X %02X\n", *tp, |
112 | (optinfo->opts[temp] & 0xFF00) >> 8); | |
1d93a9cb | 113 | return false; |
1da177e4 | 114 | } else { |
0d53778e | 115 | pr_debug("Tok "); |
1da177e4 LT |
116 | } |
117 | /* Length check */ | |
118 | if (*tp) { | |
119 | u16 spec_len; | |
120 | ||
121 | /* length field exists ? */ | |
122 | if (hdrlen < 2) | |
123 | break; | |
124 | lp = skb_header_pointer(skb, ptr + 1, | |
125 | sizeof(_optlen), | |
126 | &_optlen); | |
127 | if (lp == NULL) | |
128 | break; | |
129 | spec_len = optinfo->opts[temp] & 0x00FF; | |
130 | ||
131 | if (spec_len != 0x00FF && spec_len != *lp) { | |
0d53778e PM |
132 | pr_debug("Lbad %02X %04X\n", *lp, |
133 | spec_len); | |
1d93a9cb | 134 | return false; |
1da177e4 | 135 | } |
0d53778e | 136 | pr_debug("Lok "); |
1da177e4 LT |
137 | optlen = *lp + 2; |
138 | } else { | |
0d53778e | 139 | pr_debug("Pad1\n"); |
1da177e4 LT |
140 | optlen = 1; |
141 | } | |
142 | ||
143 | /* Step to the next */ | |
0d53778e | 144 | pr_debug("len%04X \n", optlen); |
1da177e4 LT |
145 | |
146 | if ((ptr > skb->len - optlen || hdrlen < optlen) && | |
7c4e36bc | 147 | temp < optinfo->optsnr - 1) { |
0d53778e | 148 | pr_debug("new pointer is too large! \n"); |
1da177e4 LT |
149 | break; |
150 | } | |
151 | ptr += optlen; | |
152 | hdrlen -= optlen; | |
153 | } | |
154 | if (temp == optinfo->optsnr) | |
155 | return ret; | |
f0daaa65 | 156 | else |
1d93a9cb | 157 | return false; |
1da177e4 LT |
158 | } |
159 | ||
1d93a9cb | 160 | return false; |
1da177e4 LT |
161 | } |
162 | ||
9b4fce7a | 163 | static bool hbh_mt6_check(const struct xt_mtchk_param *par) |
1da177e4 | 164 | { |
9b4fce7a | 165 | const struct ip6t_opts *optsinfo = par->matchinfo; |
f0daaa65 | 166 | |
f0daaa65 | 167 | if (optsinfo->invflags & ~IP6T_OPTS_INV_MASK) { |
0d53778e | 168 | pr_debug("ip6t_opts: unknown flags %X\n", optsinfo->invflags); |
ccb79bdc | 169 | return false; |
f0daaa65 | 170 | } |
8ca31ce5 YK |
171 | |
172 | if (optsinfo->flags & IP6T_OPTS_NSTRICT) { | |
173 | pr_debug("ip6t_opts: Not strict - not implemented"); | |
174 | return false; | |
175 | } | |
176 | ||
ccb79bdc | 177 | return true; |
1da177e4 LT |
178 | } |
179 | ||
d3c5ee6d | 180 | static struct xt_match hbh_mt6_reg[] __read_mostly = { |
5fa2a760 PM |
181 | { |
182 | .name = "hbh", | |
ee999d8b | 183 | .family = NFPROTO_IPV6, |
d3c5ee6d | 184 | .match = hbh_mt6, |
5fa2a760 | 185 | .matchsize = sizeof(struct ip6t_opts), |
d3c5ee6d | 186 | .checkentry = hbh_mt6_check, |
5fa2a760 PM |
187 | .me = THIS_MODULE, |
188 | .data = NEXTHDR_HOP, | |
189 | }, | |
190 | { | |
191 | .name = "dst", | |
ee999d8b | 192 | .family = NFPROTO_IPV6, |
d3c5ee6d | 193 | .match = hbh_mt6, |
5fa2a760 | 194 | .matchsize = sizeof(struct ip6t_opts), |
d3c5ee6d | 195 | .checkentry = hbh_mt6_check, |
5fa2a760 PM |
196 | .me = THIS_MODULE, |
197 | .data = NEXTHDR_DEST, | |
198 | }, | |
1da177e4 LT |
199 | }; |
200 | ||
d3c5ee6d | 201 | static int __init hbh_mt6_init(void) |
1da177e4 | 202 | { |
d3c5ee6d | 203 | return xt_register_matches(hbh_mt6_reg, ARRAY_SIZE(hbh_mt6_reg)); |
1da177e4 LT |
204 | } |
205 | ||
d3c5ee6d | 206 | static void __exit hbh_mt6_exit(void) |
1da177e4 | 207 | { |
d3c5ee6d | 208 | xt_unregister_matches(hbh_mt6_reg, ARRAY_SIZE(hbh_mt6_reg)); |
1da177e4 LT |
209 | } |
210 | ||
d3c5ee6d JE |
211 | module_init(hbh_mt6_init); |
212 | module_exit(hbh_mt6_exit); |