netfilter: nf_conntrack: use per-conntrack locks for protocol data
[linux-2.6.git] / net / netfilter / xt_dccp.c
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
17 #include <linux/netfilter/x_tables.h>
18 #include <linux/netfilter/xt_dccp.h>
19
20 #include <linux/netfilter_ipv4/ip_tables.h>
21 #include <linux/netfilter_ipv6/ip6_tables.h>
22
23 MODULE_LICENSE("GPL");
24 MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
25 MODULE_DESCRIPTION("Xtables: DCCP protocol packet match");
26 MODULE_ALIAS("ipt_dccp");
27 MODULE_ALIAS("ip6t_dccp");
28
29 #define DCCHECK(cond, option, flag, invflag) (!((flag) & (option)) \
30                                   || (!!((invflag) & (option)) ^ (cond)))
31
32 static unsigned char *dccp_optbuf;
33 static DEFINE_SPINLOCK(dccp_buflock);
34
35 static inline bool
36 dccp_find_option(u_int8_t option,
37                  const struct sk_buff *skb,
38                  unsigned int protoff,
39                  const struct dccp_hdr *dh,
40                  bool *hotdrop)
41 {
42         /* tcp.doff is only 4 bits, ie. max 15 * 4 bytes */
43         const unsigned char *op;
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))
49                 goto invalid;
50
51         if (!optlen)
52                 return false;
53
54         spin_lock_bh(&dccp_buflock);
55         op = skb_header_pointer(skb, protoff + optoff, optlen, dccp_optbuf);
56         if (op == NULL) {
57                 /* If we don't have the whole header, drop packet. */
58                 goto partial;
59         }
60
61         for (i = 0; i < optlen; ) {
62                 if (op[i] == option) {
63                         spin_unlock_bh(&dccp_buflock);
64                         return true;
65                 }
66
67                 if (op[i] < 2)
68                         i++;
69                 else
70                         i += op[i+1]?:1;
71         }
72
73         spin_unlock_bh(&dccp_buflock);
74         return false;
75
76 partial:
77         spin_unlock_bh(&dccp_buflock);
78 invalid:
79         *hotdrop = true;
80         return false;
81 }
82
83
84 static inline bool
85 match_types(const struct dccp_hdr *dh, u_int16_t typemask)
86 {
87         return typemask & (1 << dh->dccph_type);
88 }
89
90 static inline bool
91 match_option(u_int8_t option, const struct sk_buff *skb, unsigned int protoff,
92              const struct dccp_hdr *dh, bool *hotdrop)
93 {
94         return dccp_find_option(option, skb, protoff, dh, hotdrop);
95 }
96
97 static bool
98 dccp_mt(const struct sk_buff *skb, const struct xt_match_param *par)
99 {
100         const struct xt_dccp_info *info = par->matchinfo;
101         const struct dccp_hdr *dh;
102         struct dccp_hdr _dh;
103
104         if (par->fragoff != 0)
105                 return false;
106
107         dh = skb_header_pointer(skb, par->thoff, sizeof(_dh), &_dh);
108         if (dh == NULL) {
109                 *par->hotdrop = true;
110                 return false;
111         }
112
113         return  DCCHECK(ntohs(dh->dccph_sport) >= info->spts[0]
114                         && ntohs(dh->dccph_sport) <= info->spts[1],
115                         XT_DCCP_SRC_PORTS, info->flags, info->invflags)
116                 && DCCHECK(ntohs(dh->dccph_dport) >= info->dpts[0]
117                         && ntohs(dh->dccph_dport) <= info->dpts[1],
118                         XT_DCCP_DEST_PORTS, info->flags, info->invflags)
119                 && DCCHECK(match_types(dh, info->typemask),
120                            XT_DCCP_TYPE, info->flags, info->invflags)
121                 && DCCHECK(match_option(info->option, skb, par->thoff, dh,
122                                         par->hotdrop),
123                            XT_DCCP_OPTION, info->flags, info->invflags);
124 }
125
126 static bool dccp_mt_check(const struct xt_mtchk_param *par)
127 {
128         const struct xt_dccp_info *info = par->matchinfo;
129
130         return !(info->flags & ~XT_DCCP_VALID_FLAGS)
131                 && !(info->invflags & ~XT_DCCP_VALID_FLAGS)
132                 && !(info->invflags & ~info->flags);
133 }
134
135 static struct xt_match dccp_mt_reg[] __read_mostly = {
136         {
137                 .name           = "dccp",
138                 .family         = NFPROTO_IPV4,
139                 .checkentry     = dccp_mt_check,
140                 .match          = dccp_mt,
141                 .matchsize      = sizeof(struct xt_dccp_info),
142                 .proto          = IPPROTO_DCCP,
143                 .me             = THIS_MODULE,
144         },
145         {
146                 .name           = "dccp",
147                 .family         = NFPROTO_IPV6,
148                 .checkentry     = dccp_mt_check,
149                 .match          = dccp_mt,
150                 .matchsize      = sizeof(struct xt_dccp_info),
151                 .proto          = IPPROTO_DCCP,
152                 .me             = THIS_MODULE,
153         },
154 };
155
156 static int __init dccp_mt_init(void)
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;
166         ret = xt_register_matches(dccp_mt_reg, ARRAY_SIZE(dccp_mt_reg));
167         if (ret)
168                 goto out_kfree;
169         return ret;
170
171 out_kfree:
172         kfree(dccp_optbuf);
173         return ret;
174 }
175
176 static void __exit dccp_mt_exit(void)
177 {
178         xt_unregister_matches(dccp_mt_reg, ARRAY_SIZE(dccp_mt_reg));
179         kfree(dccp_optbuf);
180 }
181
182 module_init(dccp_mt_init);
183 module_exit(dccp_mt_exit);