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>"); | |
25 | MODULE_DESCRIPTION("Match for DCCP protocol packets"); | |
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 | ||
48 | if (dh->dccph_doff * 4 < __dccp_hdr_len(dh)) { | |
cff533ac | 49 | *hotdrop = true; |
1d93a9cb | 50 | return false; |
1d3de414 HW |
51 | } |
52 | ||
53 | if (!optlen) | |
1d93a9cb | 54 | return false; |
1d3de414 HW |
55 | |
56 | spin_lock_bh(&dccp_buflock); | |
2e4e6a17 | 57 | op = skb_header_pointer(skb, protoff + optoff, optlen, dccp_optbuf); |
1d3de414 HW |
58 | if (op == NULL) { |
59 | /* If we don't have the whole header, drop packet. */ | |
60 | spin_unlock_bh(&dccp_buflock); | |
cff533ac | 61 | *hotdrop = true; |
1d93a9cb | 62 | return false; |
1d3de414 HW |
63 | } |
64 | ||
65 | for (i = 0; i < optlen; ) { | |
66 | if (op[i] == option) { | |
67 | spin_unlock_bh(&dccp_buflock); | |
1d93a9cb | 68 | return true; |
1d3de414 HW |
69 | } |
70 | ||
601e68e1 | 71 | if (op[i] < 2) |
1d3de414 | 72 | i++; |
601e68e1 | 73 | else |
1d3de414 HW |
74 | i += op[i+1]?:1; |
75 | } | |
76 | ||
77 | spin_unlock_bh(&dccp_buflock); | |
1d93a9cb | 78 | return false; |
1d3de414 HW |
79 | } |
80 | ||
81 | ||
1d93a9cb | 82 | static inline bool |
1d3de414 HW |
83 | match_types(const struct dccp_hdr *dh, u_int16_t typemask) |
84 | { | |
7c4e36bc | 85 | return typemask & (1 << dh->dccph_type); |
1d3de414 HW |
86 | } |
87 | ||
1d93a9cb | 88 | static inline bool |
2e4e6a17 | 89 | match_option(u_int8_t option, const struct sk_buff *skb, unsigned int protoff, |
cff533ac | 90 | const struct dccp_hdr *dh, bool *hotdrop) |
1d3de414 | 91 | { |
2e4e6a17 | 92 | return dccp_find_option(option, skb, protoff, dh, hotdrop); |
1d3de414 HW |
93 | } |
94 | ||
1d93a9cb | 95 | static bool |
d3c5ee6d JE |
96 | dccp_mt(const struct sk_buff *skb, const struct net_device *in, |
97 | const struct net_device *out, const struct xt_match *match, | |
98 | const void *matchinfo, int offset, unsigned int protoff, bool *hotdrop) | |
1d3de414 | 99 | { |
3e72b2fe | 100 | const struct xt_dccp_info *info = matchinfo; |
1d3de414 HW |
101 | struct dccp_hdr _dh, *dh; |
102 | ||
103 | if (offset) | |
1d93a9cb | 104 | return false; |
601e68e1 | 105 | |
2e4e6a17 | 106 | dh = skb_header_pointer(skb, protoff, sizeof(_dh), &_dh); |
1d3de414 | 107 | if (dh == NULL) { |
cff533ac | 108 | *hotdrop = true; |
1d93a9cb | 109 | return false; |
601e68e1 | 110 | } |
1d3de414 | 111 | |
7c4e36bc JE |
112 | return DCCHECK(ntohs(dh->dccph_sport) >= info->spts[0] |
113 | && ntohs(dh->dccph_sport) <= info->spts[1], | |
601e68e1 | 114 | XT_DCCP_SRC_PORTS, info->flags, info->invflags) |
7c4e36bc JE |
115 | && DCCHECK(ntohs(dh->dccph_dport) >= info->dpts[0] |
116 | && ntohs(dh->dccph_dport) <= info->dpts[1], | |
2e4e6a17 | 117 | XT_DCCP_DEST_PORTS, info->flags, info->invflags) |
1d3de414 | 118 | && DCCHECK(match_types(dh, info->typemask), |
2e4e6a17 HW |
119 | XT_DCCP_TYPE, info->flags, info->invflags) |
120 | && DCCHECK(match_option(info->option, skb, protoff, dh, | |
121 | hotdrop), | |
122 | XT_DCCP_OPTION, info->flags, info->invflags); | |
1d3de414 HW |
123 | } |
124 | ||
ccb79bdc | 125 | static bool |
d3c5ee6d JE |
126 | dccp_mt_check(const char *tablename, const void *inf, |
127 | const struct xt_match *match, void *matchinfo, | |
128 | unsigned int hook_mask) | |
1d3de414 | 129 | { |
5d04bff0 | 130 | const struct xt_dccp_info *info = matchinfo; |
1d3de414 | 131 | |
5d04bff0 | 132 | return !(info->flags & ~XT_DCCP_VALID_FLAGS) |
2e4e6a17 HW |
133 | && !(info->invflags & ~XT_DCCP_VALID_FLAGS) |
134 | && !(info->invflags & ~info->flags); | |
135 | } | |
136 | ||
d3c5ee6d | 137 | static struct xt_match dccp_mt_reg[] __read_mostly = { |
4470bbc7 PM |
138 | { |
139 | .name = "dccp", | |
140 | .family = AF_INET, | |
d3c5ee6d JE |
141 | .checkentry = dccp_mt_check, |
142 | .match = dccp_mt, | |
4470bbc7 PM |
143 | .matchsize = sizeof(struct xt_dccp_info), |
144 | .proto = IPPROTO_DCCP, | |
145 | .me = THIS_MODULE, | |
146 | }, | |
147 | { | |
148 | .name = "dccp", | |
149 | .family = AF_INET6, | |
d3c5ee6d JE |
150 | .checkentry = dccp_mt_check, |
151 | .match = dccp_mt, | |
4470bbc7 PM |
152 | .matchsize = sizeof(struct xt_dccp_info), |
153 | .proto = IPPROTO_DCCP, | |
154 | .me = THIS_MODULE, | |
155 | }, | |
1d3de414 HW |
156 | }; |
157 | ||
d3c5ee6d | 158 | static int __init dccp_mt_init(void) |
1d3de414 HW |
159 | { |
160 | int ret; | |
161 | ||
162 | /* doff is 8 bits, so the maximum option size is (4*256). Don't put | |
163 | * this in BSS since DaveM is worried about locked TLB's for kernel | |
164 | * BSS. */ | |
165 | dccp_optbuf = kmalloc(256 * 4, GFP_KERNEL); | |
166 | if (!dccp_optbuf) | |
167 | return -ENOMEM; | |
d3c5ee6d | 168 | ret = xt_register_matches(dccp_mt_reg, ARRAY_SIZE(dccp_mt_reg)); |
1d3de414 | 169 | if (ret) |
2e4e6a17 | 170 | goto out_kfree; |
2e4e6a17 HW |
171 | return ret; |
172 | ||
2e4e6a17 HW |
173 | out_kfree: |
174 | kfree(dccp_optbuf); | |
1d3de414 HW |
175 | return ret; |
176 | } | |
177 | ||
d3c5ee6d | 178 | static void __exit dccp_mt_exit(void) |
1d3de414 | 179 | { |
d3c5ee6d | 180 | xt_unregister_matches(dccp_mt_reg, ARRAY_SIZE(dccp_mt_reg)); |
1d3de414 HW |
181 | kfree(dccp_optbuf); |
182 | } | |
183 | ||
d3c5ee6d JE |
184 | module_init(dccp_mt_init); |
185 | module_exit(dccp_mt_exit); |