Commit | Line | Data |
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1d3de414 HW |
1 | /* |
2 | * iptables module for DCCP protocol header matching | |
3 | * | |
4 | * (C) 2005 by Harald Welte <laforge@netfilter.org> | |
5 | * | |
6 | * This program is free software; you can redistribute it and/or modify | |
7 | * it under the terms of the GNU General Public License version 2 as | |
8 | * published by the Free Software Foundation. | |
9 | */ | |
10 | ||
11 | #include <linux/module.h> | |
12 | #include <linux/skbuff.h> | |
13 | #include <linux/spinlock.h> | |
14 | #include <net/ip.h> | |
15 | #include <linux/dccp.h> | |
16 | ||
2e4e6a17 HW |
17 | #include <linux/netfilter/x_tables.h> |
18 | #include <linux/netfilter/xt_dccp.h> | |
19 | ||
1d3de414 | 20 | #include <linux/netfilter_ipv4/ip_tables.h> |
2e4e6a17 HW |
21 | #include <linux/netfilter_ipv6/ip6_tables.h> |
22 | ||
23 | MODULE_LICENSE("GPL"); | |
24 | MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>"); | |
2ae15b64 | 25 | MODULE_DESCRIPTION("Xtables: DCCP protocol packet match"); |
2e4e6a17 | 26 | MODULE_ALIAS("ipt_dccp"); |
73aaf935 | 27 | MODULE_ALIAS("ip6t_dccp"); |
1d3de414 HW |
28 | |
29 | #define DCCHECK(cond, option, flag, invflag) (!((flag) & (option)) \ | |
601e68e1 | 30 | || (!!((invflag) & (option)) ^ (cond))) |
1d3de414 HW |
31 | |
32 | static unsigned char *dccp_optbuf; | |
33 | static DEFINE_SPINLOCK(dccp_buflock); | |
34 | ||
1d93a9cb | 35 | static inline bool |
1d3de414 HW |
36 | dccp_find_option(u_int8_t option, |
37 | const struct sk_buff *skb, | |
2e4e6a17 | 38 | unsigned int protoff, |
1d3de414 | 39 | const struct dccp_hdr *dh, |
cff533ac | 40 | bool *hotdrop) |
1d3de414 HW |
41 | { |
42 | /* tcp.doff is only 4 bits, ie. max 15 * 4 bytes */ | |
a47362a2 | 43 | const unsigned char *op; |
1d3de414 HW |
44 | unsigned int optoff = __dccp_hdr_len(dh); |
45 | unsigned int optlen = dh->dccph_doff*4 - __dccp_hdr_len(dh); | |
46 | unsigned int i; | |
47 | ||
79f55f11 IJ |
48 | if (dh->dccph_doff * 4 < __dccp_hdr_len(dh)) |
49 | goto invalid; | |
1d3de414 HW |
50 | |
51 | if (!optlen) | |
1d93a9cb | 52 | return false; |
1d3de414 HW |
53 | |
54 | spin_lock_bh(&dccp_buflock); | |
2e4e6a17 | 55 | op = skb_header_pointer(skb, protoff + optoff, optlen, dccp_optbuf); |
1d3de414 HW |
56 | if (op == NULL) { |
57 | /* If we don't have the whole header, drop packet. */ | |
79f55f11 | 58 | goto partial; |
1d3de414 HW |
59 | } |
60 | ||
61 | for (i = 0; i < optlen; ) { | |
62 | if (op[i] == option) { | |
63 | spin_unlock_bh(&dccp_buflock); | |
1d93a9cb | 64 | return true; |
1d3de414 HW |
65 | } |
66 | ||
601e68e1 | 67 | if (op[i] < 2) |
1d3de414 | 68 | i++; |
601e68e1 | 69 | else |
1d3de414 HW |
70 | i += op[i+1]?:1; |
71 | } | |
72 | ||
73 | spin_unlock_bh(&dccp_buflock); | |
1d93a9cb | 74 | return false; |
79f55f11 IJ |
75 | |
76 | partial: | |
77 | spin_unlock_bh(&dccp_buflock); | |
78 | invalid: | |
79 | *hotdrop = true; | |
80 | return false; | |
1d3de414 HW |
81 | } |
82 | ||
83 | ||
1d93a9cb | 84 | static inline bool |
1d3de414 HW |
85 | match_types(const struct dccp_hdr *dh, u_int16_t typemask) |
86 | { | |
7c4e36bc | 87 | return typemask & (1 << dh->dccph_type); |
1d3de414 HW |
88 | } |
89 | ||
1d93a9cb | 90 | static inline bool |
2e4e6a17 | 91 | match_option(u_int8_t option, const struct sk_buff *skb, unsigned int protoff, |
cff533ac | 92 | const struct dccp_hdr *dh, bool *hotdrop) |
1d3de414 | 93 | { |
2e4e6a17 | 94 | return dccp_find_option(option, skb, protoff, dh, hotdrop); |
1d3de414 HW |
95 | } |
96 | ||
1d93a9cb | 97 | static bool |
f7108a20 | 98 | dccp_mt(const struct sk_buff *skb, const struct xt_match_param *par) |
1d3de414 | 99 | { |
f7108a20 | 100 | const struct xt_dccp_info *info = par->matchinfo; |
3cf93c96 JE |
101 | const struct dccp_hdr *dh; |
102 | struct dccp_hdr _dh; | |
1d3de414 | 103 | |
f7108a20 | 104 | if (par->fragoff != 0) |
1d93a9cb | 105 | return false; |
601e68e1 | 106 | |
f7108a20 | 107 | dh = skb_header_pointer(skb, par->thoff, sizeof(_dh), &_dh); |
1d3de414 | 108 | if (dh == NULL) { |
f7108a20 | 109 | *par->hotdrop = true; |
1d93a9cb | 110 | return false; |
601e68e1 | 111 | } |
1d3de414 | 112 | |
7c4e36bc JE |
113 | return DCCHECK(ntohs(dh->dccph_sport) >= info->spts[0] |
114 | && ntohs(dh->dccph_sport) <= info->spts[1], | |
601e68e1 | 115 | XT_DCCP_SRC_PORTS, info->flags, info->invflags) |
7c4e36bc JE |
116 | && DCCHECK(ntohs(dh->dccph_dport) >= info->dpts[0] |
117 | && ntohs(dh->dccph_dport) <= info->dpts[1], | |
2e4e6a17 | 118 | XT_DCCP_DEST_PORTS, info->flags, info->invflags) |
1d3de414 | 119 | && DCCHECK(match_types(dh, info->typemask), |
2e4e6a17 | 120 | XT_DCCP_TYPE, info->flags, info->invflags) |
f7108a20 JE |
121 | && DCCHECK(match_option(info->option, skb, par->thoff, dh, |
122 | par->hotdrop), | |
2e4e6a17 | 123 | XT_DCCP_OPTION, info->flags, info->invflags); |
1d3de414 HW |
124 | } |
125 | ||
9b4fce7a | 126 | static bool dccp_mt_check(const struct xt_mtchk_param *par) |
1d3de414 | 127 | { |
9b4fce7a | 128 | const struct xt_dccp_info *info = par->matchinfo; |
1d3de414 | 129 | |
5d04bff0 | 130 | return !(info->flags & ~XT_DCCP_VALID_FLAGS) |
2e4e6a17 HW |
131 | && !(info->invflags & ~XT_DCCP_VALID_FLAGS) |
132 | && !(info->invflags & ~info->flags); | |
133 | } | |
134 | ||
d3c5ee6d | 135 | static struct xt_match dccp_mt_reg[] __read_mostly = { |
4470bbc7 PM |
136 | { |
137 | .name = "dccp", | |
ee999d8b | 138 | .family = NFPROTO_IPV4, |
d3c5ee6d JE |
139 | .checkentry = dccp_mt_check, |
140 | .match = dccp_mt, | |
4470bbc7 PM |
141 | .matchsize = sizeof(struct xt_dccp_info), |
142 | .proto = IPPROTO_DCCP, | |
143 | .me = THIS_MODULE, | |
144 | }, | |
145 | { | |
146 | .name = "dccp", | |
ee999d8b | 147 | .family = NFPROTO_IPV6, |
d3c5ee6d JE |
148 | .checkentry = dccp_mt_check, |
149 | .match = dccp_mt, | |
4470bbc7 PM |
150 | .matchsize = sizeof(struct xt_dccp_info), |
151 | .proto = IPPROTO_DCCP, | |
152 | .me = THIS_MODULE, | |
153 | }, | |
1d3de414 HW |
154 | }; |
155 | ||
d3c5ee6d | 156 | static int __init dccp_mt_init(void) |
1d3de414 HW |
157 | { |
158 | int ret; | |
159 | ||
160 | /* doff is 8 bits, so the maximum option size is (4*256). Don't put | |
161 | * this in BSS since DaveM is worried about locked TLB's for kernel | |
162 | * BSS. */ | |
163 | dccp_optbuf = kmalloc(256 * 4, GFP_KERNEL); | |
164 | if (!dccp_optbuf) | |
165 | return -ENOMEM; | |
d3c5ee6d | 166 | ret = xt_register_matches(dccp_mt_reg, ARRAY_SIZE(dccp_mt_reg)); |
1d3de414 | 167 | if (ret) |
2e4e6a17 | 168 | goto out_kfree; |
2e4e6a17 HW |
169 | return ret; |
170 | ||
2e4e6a17 HW |
171 | out_kfree: |
172 | kfree(dccp_optbuf); | |
1d3de414 HW |
173 | return ret; |
174 | } | |
175 | ||
d3c5ee6d | 176 | static void __exit dccp_mt_exit(void) |
1d3de414 | 177 | { |
d3c5ee6d | 178 | xt_unregister_matches(dccp_mt_reg, ARRAY_SIZE(dccp_mt_reg)); |
1d3de414 HW |
179 | kfree(dccp_optbuf); |
180 | } | |
181 | ||
d3c5ee6d JE |
182 | module_init(dccp_mt_init); |
183 | module_exit(dccp_mt_exit); |