Merge branch 'upstream' of git://ftp.linux-mips.org/pub/scm/upstream-linus
[linux-2.6] / net / ipv4 / netfilter / ipt_TOS.c
1 /* This is a module which is used for setting the TOS field of a packet. */
2
3 /* (C) 1999-2001 Paul `Rusty' Russell
4  * (C) 2002-2004 Netfilter Core Team <coreteam@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/ip.h>
14 #include <net/checksum.h>
15
16 #include <linux/netfilter_ipv4/ip_tables.h>
17 #include <linux/netfilter_ipv4/ipt_TOS.h>
18
19 MODULE_LICENSE("GPL");
20 MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>");
21 MODULE_DESCRIPTION("iptables TOS mangling module");
22
23 static unsigned int
24 target(struct sk_buff **pskb,
25        const struct net_device *in,
26        const struct net_device *out,
27        unsigned int hooknum,
28        const struct xt_target *target,
29        const void *targinfo,
30        void *userinfo)
31 {
32         const struct ipt_tos_target_info *tosinfo = targinfo;
33
34         if (((*pskb)->nh.iph->tos & IPTOS_TOS_MASK) != tosinfo->tos) {
35                 u_int16_t diffs[2];
36
37                 if (!skb_make_writable(pskb, sizeof(struct iphdr)))
38                         return NF_DROP;
39
40                 diffs[0] = htons((*pskb)->nh.iph->tos) ^ 0xFFFF;
41                 (*pskb)->nh.iph->tos
42                         = ((*pskb)->nh.iph->tos & IPTOS_PREC_MASK)
43                         | tosinfo->tos;
44                 diffs[1] = htons((*pskb)->nh.iph->tos);
45                 (*pskb)->nh.iph->check
46                         = csum_fold(csum_partial((char *)diffs,
47                                                  sizeof(diffs),
48                                                  (*pskb)->nh.iph->check
49                                                  ^0xFFFF));
50         }
51         return IPT_CONTINUE;
52 }
53
54 static int
55 checkentry(const char *tablename,
56            const void *e_void,
57            const struct xt_target *target,
58            void *targinfo,
59            unsigned int targinfosize,
60            unsigned int hook_mask)
61 {
62         const u_int8_t tos = ((struct ipt_tos_target_info *)targinfo)->tos;
63
64         if (tos != IPTOS_LOWDELAY
65             && tos != IPTOS_THROUGHPUT
66             && tos != IPTOS_RELIABILITY
67             && tos != IPTOS_MINCOST
68             && tos != IPTOS_NORMALSVC) {
69                 printk(KERN_WARNING "TOS: bad tos value %#x\n", tos);
70                 return 0;
71         }
72         return 1;
73 }
74
75 static struct ipt_target ipt_tos_reg = {
76         .name           = "TOS",
77         .target         = target,
78         .targetsize     = sizeof(struct ipt_tos_target_info),
79         .table          = "mangle",
80         .checkentry     = checkentry,
81         .me             = THIS_MODULE,
82 };
83
84 static int __init ipt_tos_init(void)
85 {
86         return ipt_register_target(&ipt_tos_reg);
87 }
88
89 static void __exit ipt_tos_fini(void)
90 {
91         ipt_unregister_target(&ipt_tos_reg);
92 }
93
94 module_init(ipt_tos_init);
95 module_exit(ipt_tos_fini);