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yaml --- r: 6312 b: refs/heads/master c: 1d3de41 h: refs/heads/master v: v3
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Harald Welte
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David S. Miller
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Aug 29, 2005
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--- | ||
refs/heads/master: e2e268665f6c01686b477a6b0cc5a70bab689d54 | ||
refs/heads/master: 1d3de414eb20d937d82c5219fd13ee4cedc499cb |
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#ifndef _IPT_DCCP_H_ | ||
#define _IPT_DCCP_H_ | ||
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#define IPT_DCCP_SRC_PORTS 0x01 | ||
#define IPT_DCCP_DEST_PORTS 0x02 | ||
#define IPT_DCCP_TYPE 0x04 | ||
#define IPT_DCCP_OPTION 0x08 | ||
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#define IPT_DCCP_VALID_FLAGS 0x0f | ||
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struct ipt_dccp_info { | ||
u_int16_t dpts[2]; /* Min, Max */ | ||
u_int16_t spts[2]; /* Min, Max */ | ||
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u_int16_t flags; | ||
u_int16_t invflags; | ||
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u_int16_t typemask; | ||
u_int8_t option; | ||
}; | ||
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#endif /* _IPT_DCCP_H_ */ | ||
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/* | ||
* iptables module for DCCP protocol header matching | ||
* | ||
* (C) 2005 by Harald Welte <laforge@netfilter.org> | ||
* | ||
* This program is free software; you can redistribute it and/or modify | ||
* it under the terms of the GNU General Public License version 2 as | ||
* published by the Free Software Foundation. | ||
*/ | ||
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#include <linux/module.h> | ||
#include <linux/skbuff.h> | ||
#include <linux/spinlock.h> | ||
#include <net/ip.h> | ||
#include <linux/dccp.h> | ||
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#include <linux/netfilter_ipv4/ip_tables.h> | ||
#include <linux/netfilter_ipv4/ipt_dccp.h> | ||
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#define DCCHECK(cond, option, flag, invflag) (!((flag) & (option)) \ | ||
|| (!!((invflag) & (option)) ^ (cond))) | ||
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static unsigned char *dccp_optbuf; | ||
static DEFINE_SPINLOCK(dccp_buflock); | ||
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static inline int | ||
dccp_find_option(u_int8_t option, | ||
const struct sk_buff *skb, | ||
const struct dccp_hdr *dh, | ||
int *hotdrop) | ||
{ | ||
/* tcp.doff is only 4 bits, ie. max 15 * 4 bytes */ | ||
unsigned char *op; | ||
unsigned int optoff = __dccp_hdr_len(dh); | ||
unsigned int optlen = dh->dccph_doff*4 - __dccp_hdr_len(dh); | ||
unsigned int i; | ||
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if (dh->dccph_doff * 4 < __dccp_hdr_len(dh)) { | ||
*hotdrop = 1; | ||
return 0; | ||
} | ||
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if (!optlen) | ||
return 0; | ||
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spin_lock_bh(&dccp_buflock); | ||
op = skb_header_pointer(skb, | ||
skb->nh.iph->ihl*4 + optoff, | ||
optlen, dccp_optbuf); | ||
if (op == NULL) { | ||
/* If we don't have the whole header, drop packet. */ | ||
spin_unlock_bh(&dccp_buflock); | ||
*hotdrop = 1; | ||
return 0; | ||
} | ||
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for (i = 0; i < optlen; ) { | ||
if (op[i] == option) { | ||
spin_unlock_bh(&dccp_buflock); | ||
return 1; | ||
} | ||
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if (op[i] < 2) | ||
i++; | ||
else | ||
i += op[i+1]?:1; | ||
} | ||
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spin_unlock_bh(&dccp_buflock); | ||
return 0; | ||
} | ||
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static inline int | ||
match_types(const struct dccp_hdr *dh, u_int16_t typemask) | ||
{ | ||
return (typemask & (1 << dh->dccph_type)); | ||
} | ||
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static inline int | ||
match_option(u_int8_t option, const struct sk_buff *skb, | ||
const struct dccp_hdr *dh, int *hotdrop) | ||
{ | ||
return dccp_find_option(option, skb, dh, hotdrop); | ||
} | ||
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static int | ||
match(const struct sk_buff *skb, | ||
const struct net_device *in, | ||
const struct net_device *out, | ||
const void *matchinfo, | ||
int offset, | ||
int *hotdrop) | ||
{ | ||
const struct ipt_dccp_info *info = | ||
(const struct ipt_dccp_info *)matchinfo; | ||
struct dccp_hdr _dh, *dh; | ||
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if (offset) | ||
return 0; | ||
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dh = skb_header_pointer(skb, skb->nh.iph->ihl*4, sizeof(_dh), &_dh); | ||
if (dh == NULL) { | ||
*hotdrop = 1; | ||
return 0; | ||
} | ||
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return DCCHECK(((ntohs(dh->dccph_sport) >= info->spts[0]) | ||
&& (ntohs(dh->dccph_sport) <= info->spts[1])), | ||
IPT_DCCP_SRC_PORTS, info->flags, info->invflags) | ||
&& DCCHECK(((ntohs(dh->dccph_dport) >= info->dpts[0]) | ||
&& (ntohs(dh->dccph_dport) <= info->dpts[1])), | ||
IPT_DCCP_DEST_PORTS, info->flags, info->invflags) | ||
&& DCCHECK(match_types(dh, info->typemask), | ||
IPT_DCCP_TYPE, info->flags, info->invflags) | ||
&& DCCHECK(match_option(info->option, skb, dh, hotdrop), | ||
IPT_DCCP_OPTION, info->flags, info->invflags); | ||
} | ||
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static int | ||
checkentry(const char *tablename, | ||
const struct ipt_ip *ip, | ||
void *matchinfo, | ||
unsigned int matchsize, | ||
unsigned int hook_mask) | ||
{ | ||
const struct ipt_dccp_info *info; | ||
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info = (const struct ipt_dccp_info *)matchinfo; | ||
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return ip->proto == IPPROTO_DCCP | ||
&& !(ip->invflags & IPT_INV_PROTO) | ||
&& matchsize == IPT_ALIGN(sizeof(struct ipt_dccp_info)) | ||
&& !(info->flags & ~IPT_DCCP_VALID_FLAGS) | ||
&& !(info->invflags & ~IPT_DCCP_VALID_FLAGS) | ||
&& !(info->invflags & ~info->flags); | ||
} | ||
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static struct ipt_match dccp_match = | ||
{ | ||
.name = "dccp", | ||
.match = &match, | ||
.checkentry = &checkentry, | ||
.me = THIS_MODULE, | ||
}; | ||
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static int __init init(void) | ||
{ | ||
int ret; | ||
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/* doff is 8 bits, so the maximum option size is (4*256). Don't put | ||
* this in BSS since DaveM is worried about locked TLB's for kernel | ||
* BSS. */ | ||
dccp_optbuf = kmalloc(256 * 4, GFP_KERNEL); | ||
if (!dccp_optbuf) | ||
return -ENOMEM; | ||
ret = ipt_register_match(&dccp_match); | ||
if (ret) | ||
kfree(dccp_optbuf); | ||
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return ret; | ||
} | ||
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static void __exit fini(void) | ||
{ | ||
ipt_unregister_match(&dccp_match); | ||
kfree(dccp_optbuf); | ||
} | ||
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module_init(init); | ||
module_exit(fini); | ||
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MODULE_LICENSE("GPL"); | ||
MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>"); | ||
MODULE_DESCRIPTION("Match for DCCP protocol packets"); | ||
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