2 * iptables module for DCCP protocol header matching
4 * (C) 2005 by Harald Welte <laforge@netfilter.org>
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.
11 #include <linux/module.h>
12 #include <linux/skbuff.h>
13 #include <linux/spinlock.h>
15 #include <linux/dccp.h>
17 #include <linux/netfilter_ipv4/ip_tables.h>
18 #include <linux/netfilter_ipv4/ipt_dccp.h>
20 #define DCCHECK(cond, option, flag, invflag) (!((flag) & (option)) \
21 || (!!((invflag) & (option)) ^ (cond)))
23 static unsigned char *dccp_optbuf
;
24 static DEFINE_SPINLOCK(dccp_buflock
);
27 dccp_find_option(u_int8_t option
,
28 const struct sk_buff
*skb
,
29 const struct dccp_hdr
*dh
,
32 /* tcp.doff is only 4 bits, ie. max 15 * 4 bytes */
34 unsigned int optoff
= __dccp_hdr_len(dh
);
35 unsigned int optlen
= dh
->dccph_doff
*4 - __dccp_hdr_len(dh
);
38 if (dh
->dccph_doff
* 4 < __dccp_hdr_len(dh
)) {
46 spin_lock_bh(&dccp_buflock
);
47 op
= skb_header_pointer(skb
,
48 skb
->nh
.iph
->ihl
*4 + optoff
,
51 /* If we don't have the whole header, drop packet. */
52 spin_unlock_bh(&dccp_buflock
);
57 for (i
= 0; i
< optlen
; ) {
58 if (op
[i
] == option
) {
59 spin_unlock_bh(&dccp_buflock
);
69 spin_unlock_bh(&dccp_buflock
);
75 match_types(const struct dccp_hdr
*dh
, u_int16_t typemask
)
77 return (typemask
& (1 << dh
->dccph_type
));
81 match_option(u_int8_t option
, const struct sk_buff
*skb
,
82 const struct dccp_hdr
*dh
, int *hotdrop
)
84 return dccp_find_option(option
, skb
, dh
, hotdrop
);
88 match(const struct sk_buff
*skb
,
89 const struct net_device
*in
,
90 const struct net_device
*out
,
91 const void *matchinfo
,
95 const struct ipt_dccp_info
*info
=
96 (const struct ipt_dccp_info
*)matchinfo
;
97 struct dccp_hdr _dh
, *dh
;
102 dh
= skb_header_pointer(skb
, skb
->nh
.iph
->ihl
*4, sizeof(_dh
), &_dh
);
108 return DCCHECK(((ntohs(dh
->dccph_sport
) >= info
->spts
[0])
109 && (ntohs(dh
->dccph_sport
) <= info
->spts
[1])),
110 IPT_DCCP_SRC_PORTS
, info
->flags
, info
->invflags
)
111 && DCCHECK(((ntohs(dh
->dccph_dport
) >= info
->dpts
[0])
112 && (ntohs(dh
->dccph_dport
) <= info
->dpts
[1])),
113 IPT_DCCP_DEST_PORTS
, info
->flags
, info
->invflags
)
114 && DCCHECK(match_types(dh
, info
->typemask
),
115 IPT_DCCP_TYPE
, info
->flags
, info
->invflags
)
116 && DCCHECK(match_option(info
->option
, skb
, dh
, hotdrop
),
117 IPT_DCCP_OPTION
, info
->flags
, info
->invflags
);
121 checkentry(const char *tablename
,
122 const struct ipt_ip
*ip
,
124 unsigned int matchsize
,
125 unsigned int hook_mask
)
127 const struct ipt_dccp_info
*info
;
129 info
= (const struct ipt_dccp_info
*)matchinfo
;
131 return ip
->proto
== IPPROTO_DCCP
132 && !(ip
->invflags
& IPT_INV_PROTO
)
133 && matchsize
== IPT_ALIGN(sizeof(struct ipt_dccp_info
))
134 && !(info
->flags
& ~IPT_DCCP_VALID_FLAGS
)
135 && !(info
->invflags
& ~IPT_DCCP_VALID_FLAGS
)
136 && !(info
->invflags
& ~info
->flags
);
139 static struct ipt_match dccp_match
=
143 .checkentry
= &checkentry
,
147 static int __init
init(void)
151 /* doff is 8 bits, so the maximum option size is (4*256). Don't put
152 * this in BSS since DaveM is worried about locked TLB's for kernel
154 dccp_optbuf
= kmalloc(256 * 4, GFP_KERNEL
);
157 ret
= ipt_register_match(&dccp_match
);
164 static void __exit
fini(void)
166 ipt_unregister_match(&dccp_match
);
173 MODULE_LICENSE("GPL");
174 MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
175 MODULE_DESCRIPTION("Match for DCCP protocol packets");