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/x_tables.h>
18 #include <linux/netfilter/xt_dccp.h>
20 #include <linux/netfilter_ipv4/ip_tables.h>
21 #include <linux/netfilter_ipv6/ip6_tables.h>
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");
29 #define DCCHECK(cond, option, flag, invflag) (!((flag) & (option)) \
30 || (!!((invflag) & (option)) ^ (cond)))
32 static unsigned char *dccp_optbuf
;
33 static DEFINE_SPINLOCK(dccp_buflock
);
36 dccp_find_option(u_int8_t option
,
37 const struct sk_buff
*skb
,
39 const struct dccp_hdr
*dh
,
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
);
48 if (dh
->dccph_doff
* 4 < __dccp_hdr_len(dh
))
54 spin_lock_bh(&dccp_buflock
);
55 op
= skb_header_pointer(skb
, protoff
+ optoff
, optlen
, dccp_optbuf
);
57 /* If we don't have the whole header, drop packet. */
61 for (i
= 0; i
< optlen
; ) {
62 if (op
[i
] == option
) {
63 spin_unlock_bh(&dccp_buflock
);
73 spin_unlock_bh(&dccp_buflock
);
77 spin_unlock_bh(&dccp_buflock
);
85 match_types(const struct dccp_hdr
*dh
, u_int16_t typemask
)
87 return typemask
& (1 << dh
->dccph_type
);
91 match_option(u_int8_t option
, const struct sk_buff
*skb
, unsigned int protoff
,
92 const struct dccp_hdr
*dh
, bool *hotdrop
)
94 return dccp_find_option(option
, skb
, protoff
, dh
, hotdrop
);
98 dccp_mt(const struct sk_buff
*skb
, const struct xt_match_param
*par
)
100 const struct xt_dccp_info
*info
= par
->matchinfo
;
101 const struct dccp_hdr
*dh
;
104 if (par
->fragoff
!= 0)
107 dh
= skb_header_pointer(skb
, par
->thoff
, sizeof(_dh
), &_dh
);
109 *par
->hotdrop
= true;
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
,
123 XT_DCCP_OPTION
, info
->flags
, info
->invflags
);
126 static bool dccp_mt_check(const struct xt_mtchk_param
*par
)
128 const struct xt_dccp_info
*info
= par
->matchinfo
;
130 return !(info
->flags
& ~XT_DCCP_VALID_FLAGS
)
131 && !(info
->invflags
& ~XT_DCCP_VALID_FLAGS
)
132 && !(info
->invflags
& ~info
->flags
);
135 static struct xt_match dccp_mt_reg
[] __read_mostly
= {
138 .family
= NFPROTO_IPV4
,
139 .checkentry
= dccp_mt_check
,
141 .matchsize
= sizeof(struct xt_dccp_info
),
142 .proto
= IPPROTO_DCCP
,
147 .family
= NFPROTO_IPV6
,
148 .checkentry
= dccp_mt_check
,
150 .matchsize
= sizeof(struct xt_dccp_info
),
151 .proto
= IPPROTO_DCCP
,
156 static int __init
dccp_mt_init(void)
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
163 dccp_optbuf
= kmalloc(256 * 4, GFP_KERNEL
);
166 ret
= xt_register_matches(dccp_mt_reg
, ARRAY_SIZE(dccp_mt_reg
));
176 static void __exit
dccp_mt_exit(void)
178 xt_unregister_matches(dccp_mt_reg
, ARRAY_SIZE(dccp_mt_reg
));
182 module_init(dccp_mt_init
);
183 module_exit(dccp_mt_exit
);
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