1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
|
/* iptables module for setting the IPv4 DSCP field, Version 1.8
*
* (C) 2002 by Harald Welte <laforge@gnumonks.org>
* based on ipt_FTOS.c (C) 2000 by Matthew G. Marsh <mgm@paktronix.com>
* This software is distributed under GNU GPL v2, 1991
*
* See RFC2474 for a description of the DSCP field within the IP Header.
*
* ipt_DSCP.c,v 1.8 2002/08/06 18:41:57 laforge Exp
*/
#include <linux/module.h>
#include <linux/skbuff.h>
#include <linux/ip.h>
#include <net/checksum.h>
#include <linux/netfilter_ipv4/ip_tables.h>
#include <linux/netfilter_ipv4/ipt_DSCP.h>
MODULE_AUTHOR("Harald Welte <laforge@gnumonks.org>");
MODULE_DESCRIPTION("IP tables DSCP modification module");
MODULE_LICENSE("GPL");
static unsigned int
target(struct sk_buff **pskb,
unsigned int hooknum,
const struct net_device *in,
const struct net_device *out,
const void *targinfo,
void *userinfo)
{
struct iphdr *iph = (*pskb)->nh.iph;
const struct ipt_DSCP_info *dinfo = targinfo;
u_int8_t sh_dscp = ((dinfo->dscp << IPT_DSCP_SHIFT) & IPT_DSCP_MASK);
if ((iph->tos & IPT_DSCP_MASK) != sh_dscp) {
u_int16_t diffs[2];
/* raw socket (tcpdump) may have clone of incoming
* skb: don't disturb it --RR */
if (skb_cloned(*pskb) && !(*pskb)->sk) {
struct sk_buff *nskb = skb_copy(*pskb, GFP_ATOMIC);
if (!nskb)
return NF_DROP;
kfree_skb(*pskb);
*pskb = nskb;
iph = (*pskb)->nh.iph;
}
diffs[0] = htons(iph->tos) ^ 0xFFFF;
iph->tos = (iph->tos & ~IPT_DSCP_MASK) | sh_dscp;
diffs[1] = htons(iph->tos);
iph->check = csum_fold(csum_partial((char *)diffs,
sizeof(diffs),
iph->check^0xFFFF));
(*pskb)->nfcache |= NFC_ALTERED;
}
return IPT_CONTINUE;
}
static int
checkentry(const char *tablename,
const struct ipt_entry *e,
void *targinfo,
unsigned int targinfosize,
unsigned int hook_mask)
{
const u_int8_t dscp = ((struct ipt_DSCP_info *)targinfo)->dscp;
if (targinfosize != IPT_ALIGN(sizeof(struct ipt_DSCP_info))) {
printk(KERN_WARNING "DSCP: targinfosize %u != %Zu\n",
targinfosize,
IPT_ALIGN(sizeof(struct ipt_DSCP_info)));
return 0;
}
if (strcmp(tablename, "mangle") != 0) {
printk(KERN_WARNING "DSCP: can only be called from \"mangle\" table, not \"%s\"\n", tablename);
return 0;
}
if ((dscp > IPT_DSCP_MAX)) {
printk(KERN_WARNING "DSCP: dscp %x out of range\n", dscp);
return 0;
}
return 1;
}
static struct ipt_target ipt_dscp_reg
= { { NULL, NULL }, "DSCP", target, checkentry, NULL, THIS_MODULE };
static int __init init(void)
{
if (ipt_register_target(&ipt_dscp_reg))
return -EINVAL;
return 0;
}
static void __exit fini(void)
{
ipt_unregister_target(&ipt_dscp_reg);
}
module_init(init);
module_exit(fini);
|
