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"); | |
1d3de414 HW |
27 | |
28 | #define DCCHECK(cond, option, flag, invflag) (!((flag) & (option)) \ | |
29 | || (!!((invflag) & (option)) ^ (cond))) | |
30 | ||
31 | static unsigned char *dccp_optbuf; | |
32 | static DEFINE_SPINLOCK(dccp_buflock); | |
33 | ||
34 | static inline int | |
35 | dccp_find_option(u_int8_t option, | |
36 | const struct sk_buff *skb, | |
2e4e6a17 | 37 | unsigned int protoff, |
1d3de414 HW |
38 | const struct dccp_hdr *dh, |
39 | int *hotdrop) | |
40 | { | |
41 | /* tcp.doff is only 4 bits, ie. max 15 * 4 bytes */ | |
42 | unsigned char *op; | |
43 | unsigned int optoff = __dccp_hdr_len(dh); | |
44 | unsigned int optlen = dh->dccph_doff*4 - __dccp_hdr_len(dh); | |
45 | unsigned int i; | |
46 | ||
47 | if (dh->dccph_doff * 4 < __dccp_hdr_len(dh)) { | |
48 | *hotdrop = 1; | |
49 | return 0; | |
50 | } | |
51 | ||
52 | if (!optlen) | |
53 | return 0; | |
54 | ||
55 | spin_lock_bh(&dccp_buflock); | |
2e4e6a17 | 56 | op = skb_header_pointer(skb, protoff + optoff, optlen, dccp_optbuf); |
1d3de414 HW |
57 | if (op == NULL) { |
58 | /* If we don't have the whole header, drop packet. */ | |
59 | spin_unlock_bh(&dccp_buflock); | |
60 | *hotdrop = 1; | |
61 | return 0; | |
62 | } | |
63 | ||
64 | for (i = 0; i < optlen; ) { | |
65 | if (op[i] == option) { | |
66 | spin_unlock_bh(&dccp_buflock); | |
67 | return 1; | |
68 | } | |
69 | ||
70 | if (op[i] < 2) | |
71 | i++; | |
72 | else | |
73 | i += op[i+1]?:1; | |
74 | } | |
75 | ||
76 | spin_unlock_bh(&dccp_buflock); | |
77 | return 0; | |
78 | } | |
79 | ||
80 | ||
81 | static inline int | |
82 | match_types(const struct dccp_hdr *dh, u_int16_t typemask) | |
83 | { | |
84 | return (typemask & (1 << dh->dccph_type)); | |
85 | } | |
86 | ||
87 | static inline int | |
2e4e6a17 | 88 | match_option(u_int8_t option, const struct sk_buff *skb, unsigned int protoff, |
1d3de414 HW |
89 | const struct dccp_hdr *dh, int *hotdrop) |
90 | { | |
2e4e6a17 | 91 | return dccp_find_option(option, skb, protoff, dh, hotdrop); |
1d3de414 HW |
92 | } |
93 | ||
94 | static int | |
95 | match(const struct sk_buff *skb, | |
96 | const struct net_device *in, | |
97 | const struct net_device *out, | |
c4986734 | 98 | const struct xt_match *match, |
1d3de414 HW |
99 | const void *matchinfo, |
100 | int offset, | |
2e4e6a17 | 101 | unsigned int protoff, |
1d3de414 HW |
102 | int *hotdrop) |
103 | { | |
2e4e6a17 HW |
104 | const struct xt_dccp_info *info = |
105 | (const struct xt_dccp_info *)matchinfo; | |
1d3de414 HW |
106 | struct dccp_hdr _dh, *dh; |
107 | ||
108 | if (offset) | |
109 | return 0; | |
110 | ||
2e4e6a17 | 111 | dh = skb_header_pointer(skb, protoff, sizeof(_dh), &_dh); |
1d3de414 HW |
112 | if (dh == NULL) { |
113 | *hotdrop = 1; | |
114 | return 0; | |
115 | } | |
116 | ||
117 | return DCCHECK(((ntohs(dh->dccph_sport) >= info->spts[0]) | |
118 | && (ntohs(dh->dccph_sport) <= info->spts[1])), | |
2e4e6a17 | 119 | XT_DCCP_SRC_PORTS, info->flags, info->invflags) |
1d3de414 HW |
120 | && DCCHECK(((ntohs(dh->dccph_dport) >= info->dpts[0]) |
121 | && (ntohs(dh->dccph_dport) <= info->dpts[1])), | |
2e4e6a17 | 122 | XT_DCCP_DEST_PORTS, info->flags, info->invflags) |
1d3de414 | 123 | && DCCHECK(match_types(dh, info->typemask), |
2e4e6a17 HW |
124 | XT_DCCP_TYPE, info->flags, info->invflags) |
125 | && DCCHECK(match_option(info->option, skb, protoff, dh, | |
126 | hotdrop), | |
127 | XT_DCCP_OPTION, info->flags, info->invflags); | |
1d3de414 HW |
128 | } |
129 | ||
130 | static int | |
131 | checkentry(const char *tablename, | |
2e4e6a17 | 132 | const void *inf, |
c4986734 | 133 | const struct xt_match *match, |
1d3de414 HW |
134 | void *matchinfo, |
135 | unsigned int matchsize, | |
136 | unsigned int hook_mask) | |
137 | { | |
5d04bff0 | 138 | const struct xt_dccp_info *info = matchinfo; |
1d3de414 | 139 | |
5d04bff0 | 140 | return !(info->flags & ~XT_DCCP_VALID_FLAGS) |
2e4e6a17 HW |
141 | && !(info->invflags & ~XT_DCCP_VALID_FLAGS) |
142 | && !(info->invflags & ~info->flags); | |
143 | } | |
144 | ||
2e4e6a17 | 145 | static struct xt_match dccp_match = |
1d3de414 HW |
146 | { |
147 | .name = "dccp", | |
5d04bff0 PM |
148 | .match = match, |
149 | .matchsize = sizeof(struct xt_dccp_info), | |
150 | .proto = IPPROTO_DCCP, | |
151 | .checkentry = checkentry, | |
a45049c5 | 152 | .family = AF_INET, |
1d3de414 HW |
153 | .me = THIS_MODULE, |
154 | }; | |
2e4e6a17 HW |
155 | static struct xt_match dccp6_match = |
156 | { | |
157 | .name = "dccp", | |
5d04bff0 PM |
158 | .match = match, |
159 | .matchsize = sizeof(struct xt_dccp_info), | |
160 | .proto = IPPROTO_DCCP, | |
161 | .checkentry = checkentry, | |
a45049c5 | 162 | .family = AF_INET6, |
2e4e6a17 HW |
163 | .me = THIS_MODULE, |
164 | }; | |
165 | ||
1d3de414 HW |
166 | |
167 | static int __init init(void) | |
168 | { | |
169 | int ret; | |
170 | ||
171 | /* doff is 8 bits, so the maximum option size is (4*256). Don't put | |
172 | * this in BSS since DaveM is worried about locked TLB's for kernel | |
173 | * BSS. */ | |
174 | dccp_optbuf = kmalloc(256 * 4, GFP_KERNEL); | |
175 | if (!dccp_optbuf) | |
176 | return -ENOMEM; | |
a45049c5 | 177 | ret = xt_register_match(&dccp_match); |
1d3de414 | 178 | if (ret) |
2e4e6a17 | 179 | goto out_kfree; |
a45049c5 | 180 | ret = xt_register_match(&dccp6_match); |
2e4e6a17 HW |
181 | if (ret) |
182 | goto out_unreg; | |
183 | ||
184 | return ret; | |
185 | ||
186 | out_unreg: | |
a45049c5 | 187 | xt_unregister_match(&dccp_match); |
2e4e6a17 HW |
188 | out_kfree: |
189 | kfree(dccp_optbuf); | |
1d3de414 HW |
190 | |
191 | return ret; | |
192 | } | |
193 | ||
194 | static void __exit fini(void) | |
195 | { | |
a45049c5 PNA |
196 | xt_unregister_match(&dccp6_match); |
197 | xt_unregister_match(&dccp_match); | |
1d3de414 HW |
198 | kfree(dccp_optbuf); |
199 | } | |
200 | ||
201 | module_init(init); | |
202 | module_exit(fini); |