Phonet: basic net namespace support
[linux-3.10.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                 *hotdrop = true;
50                 return false;
51         }
52
53         if (!optlen)
54                 return false;
55
56         spin_lock_bh(&dccp_buflock);
57         op = skb_header_pointer(skb, protoff + optoff, optlen, dccp_optbuf);
58         if (op == NULL) {
59                 /* If we don't have the whole header, drop packet. */
60                 spin_unlock_bh(&dccp_buflock);
61                 *hotdrop = true;
62                 return false;
63         }
64
65         for (i = 0; i < optlen; ) {
66                 if (op[i] == option) {
67                         spin_unlock_bh(&dccp_buflock);
68                         return true;
69                 }
70
71                 if (op[i] < 2)
72                         i++;
73                 else
74                         i += op[i+1]?:1;
75         }
76
77         spin_unlock_bh(&dccp_buflock);
78         return false;
79 }
80
81
82 static inline bool
83 match_types(const struct dccp_hdr *dh, u_int16_t typemask)
84 {
85         return typemask & (1 << dh->dccph_type);
86 }
87
88 static inline bool
89 match_option(u_int8_t option, const struct sk_buff *skb, unsigned int protoff,
90              const struct dccp_hdr *dh, bool *hotdrop)
91 {
92         return dccp_find_option(option, skb, protoff, dh, hotdrop);
93 }
94
95 static bool
96 dccp_mt(const struct sk_buff *skb, const struct xt_match_param *par)
97 {
98         const struct xt_dccp_info *info = par->matchinfo;
99         const struct dccp_hdr *dh;
100         struct dccp_hdr _dh;
101
102         if (par->fragoff != 0)
103                 return false;
104
105         dh = skb_header_pointer(skb, par->thoff, sizeof(_dh), &_dh);
106         if (dh == NULL) {
107                 *par->hotdrop = true;
108                 return false;
109         }
110
111         return  DCCHECK(ntohs(dh->dccph_sport) >= info->spts[0]
112                         && ntohs(dh->dccph_sport) <= info->spts[1],
113                         XT_DCCP_SRC_PORTS, info->flags, info->invflags)
114                 && DCCHECK(ntohs(dh->dccph_dport) >= info->dpts[0]
115                         && ntohs(dh->dccph_dport) <= info->dpts[1],
116                         XT_DCCP_DEST_PORTS, info->flags, info->invflags)
117                 && DCCHECK(match_types(dh, info->typemask),
118                            XT_DCCP_TYPE, info->flags, info->invflags)
119                 && DCCHECK(match_option(info->option, skb, par->thoff, dh,
120                                         par->hotdrop),
121                            XT_DCCP_OPTION, info->flags, info->invflags);
122 }
123
124 static bool dccp_mt_check(const struct xt_mtchk_param *par)
125 {
126         const struct xt_dccp_info *info = par->matchinfo;
127
128         return !(info->flags & ~XT_DCCP_VALID_FLAGS)
129                 && !(info->invflags & ~XT_DCCP_VALID_FLAGS)
130                 && !(info->invflags & ~info->flags);
131 }
132
133 static struct xt_match dccp_mt_reg[] __read_mostly = {
134         {
135                 .name           = "dccp",
136                 .family         = NFPROTO_IPV4,
137                 .checkentry     = dccp_mt_check,
138                 .match          = dccp_mt,
139                 .matchsize      = sizeof(struct xt_dccp_info),
140                 .proto          = IPPROTO_DCCP,
141                 .me             = THIS_MODULE,
142         },
143         {
144                 .name           = "dccp",
145                 .family         = NFPROTO_IPV6,
146                 .checkentry     = dccp_mt_check,
147                 .match          = dccp_mt,
148                 .matchsize      = sizeof(struct xt_dccp_info),
149                 .proto          = IPPROTO_DCCP,
150                 .me             = THIS_MODULE,
151         },
152 };
153
154 static int __init dccp_mt_init(void)
155 {
156         int ret;
157
158         /* doff is 8 bits, so the maximum option size is (4*256).  Don't put
159          * this in BSS since DaveM is worried about locked TLB's for kernel
160          * BSS. */
161         dccp_optbuf = kmalloc(256 * 4, GFP_KERNEL);
162         if (!dccp_optbuf)
163                 return -ENOMEM;
164         ret = xt_register_matches(dccp_mt_reg, ARRAY_SIZE(dccp_mt_reg));
165         if (ret)
166                 goto out_kfree;
167         return ret;
168
169 out_kfree:
170         kfree(dccp_optbuf);
171         return ret;
172 }
173
174 static void __exit dccp_mt_exit(void)
175 {
176         xt_unregister_matches(dccp_mt_reg, ARRAY_SIZE(dccp_mt_reg));
177         kfree(dccp_optbuf);
178 }
179
180 module_init(dccp_mt_init);
181 module_exit(dccp_mt_exit);