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 | { | |
3e72b2fe | 104 | const struct xt_dccp_info *info = matchinfo; |
1d3de414 HW |
105 | struct dccp_hdr _dh, *dh; |
106 | ||
107 | if (offset) | |
108 | return 0; | |
109 | ||
2e4e6a17 | 110 | dh = skb_header_pointer(skb, protoff, sizeof(_dh), &_dh); |
1d3de414 HW |
111 | if (dh == NULL) { |
112 | *hotdrop = 1; | |
113 | return 0; | |
114 | } | |
115 | ||
116 | return DCCHECK(((ntohs(dh->dccph_sport) >= info->spts[0]) | |
117 | && (ntohs(dh->dccph_sport) <= info->spts[1])), | |
2e4e6a17 | 118 | XT_DCCP_SRC_PORTS, info->flags, info->invflags) |
1d3de414 HW |
119 | && DCCHECK(((ntohs(dh->dccph_dport) >= info->dpts[0]) |
120 | && (ntohs(dh->dccph_dport) <= info->dpts[1])), | |
2e4e6a17 | 121 | XT_DCCP_DEST_PORTS, info->flags, info->invflags) |
1d3de414 | 122 | && DCCHECK(match_types(dh, info->typemask), |
2e4e6a17 HW |
123 | XT_DCCP_TYPE, info->flags, info->invflags) |
124 | && DCCHECK(match_option(info->option, skb, protoff, dh, | |
125 | hotdrop), | |
126 | XT_DCCP_OPTION, info->flags, info->invflags); | |
1d3de414 HW |
127 | } |
128 | ||
129 | static int | |
130 | checkentry(const char *tablename, | |
2e4e6a17 | 131 | const void *inf, |
c4986734 | 132 | const struct xt_match *match, |
1d3de414 HW |
133 | void *matchinfo, |
134 | unsigned int matchsize, | |
135 | unsigned int hook_mask) | |
136 | { | |
5d04bff0 | 137 | const struct xt_dccp_info *info = matchinfo; |
1d3de414 | 138 | |
5d04bff0 | 139 | return !(info->flags & ~XT_DCCP_VALID_FLAGS) |
2e4e6a17 HW |
140 | && !(info->invflags & ~XT_DCCP_VALID_FLAGS) |
141 | && !(info->invflags & ~info->flags); | |
142 | } | |
143 | ||
2e4e6a17 | 144 | static struct xt_match dccp_match = |
1d3de414 HW |
145 | { |
146 | .name = "dccp", | |
5d04bff0 PM |
147 | .match = match, |
148 | .matchsize = sizeof(struct xt_dccp_info), | |
149 | .proto = IPPROTO_DCCP, | |
150 | .checkentry = checkentry, | |
a45049c5 | 151 | .family = AF_INET, |
1d3de414 HW |
152 | .me = THIS_MODULE, |
153 | }; | |
2e4e6a17 HW |
154 | static struct xt_match dccp6_match = |
155 | { | |
156 | .name = "dccp", | |
5d04bff0 PM |
157 | .match = match, |
158 | .matchsize = sizeof(struct xt_dccp_info), | |
159 | .proto = IPPROTO_DCCP, | |
160 | .checkentry = checkentry, | |
a45049c5 | 161 | .family = AF_INET6, |
2e4e6a17 HW |
162 | .me = THIS_MODULE, |
163 | }; | |
164 | ||
1d3de414 | 165 | |
65b4b4e8 | 166 | static int __init xt_dccp_init(void) |
1d3de414 HW |
167 | { |
168 | int ret; | |
169 | ||
170 | /* doff is 8 bits, so the maximum option size is (4*256). Don't put | |
171 | * this in BSS since DaveM is worried about locked TLB's for kernel | |
172 | * BSS. */ | |
173 | dccp_optbuf = kmalloc(256 * 4, GFP_KERNEL); | |
174 | if (!dccp_optbuf) | |
175 | return -ENOMEM; | |
a45049c5 | 176 | ret = xt_register_match(&dccp_match); |
1d3de414 | 177 | if (ret) |
2e4e6a17 | 178 | goto out_kfree; |
a45049c5 | 179 | ret = xt_register_match(&dccp6_match); |
2e4e6a17 HW |
180 | if (ret) |
181 | goto out_unreg; | |
182 | ||
183 | return ret; | |
184 | ||
185 | out_unreg: | |
a45049c5 | 186 | xt_unregister_match(&dccp_match); |
2e4e6a17 HW |
187 | out_kfree: |
188 | kfree(dccp_optbuf); | |
1d3de414 HW |
189 | |
190 | return ret; | |
191 | } | |
192 | ||
65b4b4e8 | 193 | static void __exit xt_dccp_fini(void) |
1d3de414 | 194 | { |
a45049c5 PNA |
195 | xt_unregister_match(&dccp6_match); |
196 | xt_unregister_match(&dccp_match); | |
1d3de414 HW |
197 | kfree(dccp_optbuf); |
198 | } | |
199 | ||
65b4b4e8 AM |
200 | module_init(xt_dccp_init); |
201 | module_exit(xt_dccp_fini); |