netfilter: nf_conntrack: use per-conntrack locks for protocol data
[linux-2.6.git] / net / netfilter / xt_HL.c
1 /*
2  * TTL modification target for IP tables
3  * (C) 2000,2005 by Harald Welte <laforge@netfilter.org>
4  *
5  * Hop Limit modification target for ip6tables
6  * Maciej Soltysiak <solt@dns.toxicfilms.tv>
7  *
8  * This program is free software; you can redistribute it and/or modify
9  * it under the terms of the GNU General Public License version 2 as
10  * published by the Free Software Foundation.
11  */
12
13 #include <linux/module.h>
14 #include <linux/skbuff.h>
15 #include <linux/ip.h>
16 #include <linux/ipv6.h>
17 #include <net/checksum.h>
18
19 #include <linux/netfilter/x_tables.h>
20 #include <linux/netfilter_ipv4/ipt_TTL.h>
21 #include <linux/netfilter_ipv6/ip6t_HL.h>
22
23 MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
24 MODULE_AUTHOR("Maciej Soltysiak <solt@dns.toxicfilms.tv>");
25 MODULE_DESCRIPTION("Xtables: Hoplimit/TTL Limit field modification target");
26 MODULE_LICENSE("GPL");
27
28 static unsigned int
29 ttl_tg(struct sk_buff *skb, const struct xt_target_param *par)
30 {
31         struct iphdr *iph;
32         const struct ipt_TTL_info *info = par->targinfo;
33         int new_ttl;
34
35         if (!skb_make_writable(skb, skb->len))
36                 return NF_DROP;
37
38         iph = ip_hdr(skb);
39
40         switch (info->mode) {
41                 case IPT_TTL_SET:
42                         new_ttl = info->ttl;
43                         break;
44                 case IPT_TTL_INC:
45                         new_ttl = iph->ttl + info->ttl;
46                         if (new_ttl > 255)
47                                 new_ttl = 255;
48                         break;
49                 case IPT_TTL_DEC:
50                         new_ttl = iph->ttl - info->ttl;
51                         if (new_ttl < 0)
52                                 new_ttl = 0;
53                         break;
54                 default:
55                         new_ttl = iph->ttl;
56                         break;
57         }
58
59         if (new_ttl != iph->ttl) {
60                 csum_replace2(&iph->check, htons(iph->ttl << 8),
61                                            htons(new_ttl << 8));
62                 iph->ttl = new_ttl;
63         }
64
65         return XT_CONTINUE;
66 }
67
68 static unsigned int
69 hl_tg6(struct sk_buff *skb, const struct xt_target_param *par)
70 {
71         struct ipv6hdr *ip6h;
72         const struct ip6t_HL_info *info = par->targinfo;
73         int new_hl;
74
75         if (!skb_make_writable(skb, skb->len))
76                 return NF_DROP;
77
78         ip6h = ipv6_hdr(skb);
79
80         switch (info->mode) {
81                 case IP6T_HL_SET:
82                         new_hl = info->hop_limit;
83                         break;
84                 case IP6T_HL_INC:
85                         new_hl = ip6h->hop_limit + info->hop_limit;
86                         if (new_hl > 255)
87                                 new_hl = 255;
88                         break;
89                 case IP6T_HL_DEC:
90                         new_hl = ip6h->hop_limit - info->hop_limit;
91                         if (new_hl < 0)
92                                 new_hl = 0;
93                         break;
94                 default:
95                         new_hl = ip6h->hop_limit;
96                         break;
97         }
98
99         ip6h->hop_limit = new_hl;
100
101         return XT_CONTINUE;
102 }
103
104 static bool ttl_tg_check(const struct xt_tgchk_param *par)
105 {
106         const struct ipt_TTL_info *info = par->targinfo;
107
108         if (info->mode > IPT_TTL_MAXMODE) {
109                 printk(KERN_WARNING "ipt_TTL: invalid or unknown Mode %u\n",
110                         info->mode);
111                 return false;
112         }
113         if (info->mode != IPT_TTL_SET && info->ttl == 0)
114                 return false;
115         return true;
116 }
117
118 static bool hl_tg6_check(const struct xt_tgchk_param *par)
119 {
120         const struct ip6t_HL_info *info = par->targinfo;
121
122         if (info->mode > IP6T_HL_MAXMODE) {
123                 printk(KERN_WARNING "ip6t_HL: invalid or unknown Mode %u\n",
124                         info->mode);
125                 return false;
126         }
127         if (info->mode != IP6T_HL_SET && info->hop_limit == 0) {
128                 printk(KERN_WARNING "ip6t_HL: increment/decrement doesn't "
129                         "make sense with value 0\n");
130                 return false;
131         }
132         return true;
133 }
134
135 static struct xt_target hl_tg_reg[] __read_mostly = {
136         {
137                 .name       = "TTL",
138                 .revision   = 0,
139                 .family     = NFPROTO_IPV4,
140                 .target     = ttl_tg,
141                 .targetsize = sizeof(struct ipt_TTL_info),
142                 .table      = "mangle",
143                 .checkentry = ttl_tg_check,
144                 .me         = THIS_MODULE,
145         },
146         {
147                 .name       = "HL",
148                 .revision   = 0,
149                 .family     = NFPROTO_IPV6,
150                 .target     = hl_tg6,
151                 .targetsize = sizeof(struct ip6t_HL_info),
152                 .table      = "mangle",
153                 .checkentry = hl_tg6_check,
154                 .me         = THIS_MODULE,
155         },
156 };
157
158 static int __init hl_tg_init(void)
159 {
160         return xt_register_targets(hl_tg_reg, ARRAY_SIZE(hl_tg_reg));
161 }
162
163 static void __exit hl_tg_exit(void)
164 {
165         xt_unregister_targets(hl_tg_reg, ARRAY_SIZE(hl_tg_reg));
166 }
167
168 module_init(hl_tg_init);
169 module_exit(hl_tg_exit);
170 MODULE_ALIAS("ipt_TTL");
171 MODULE_ALIAS("ip6t_HL");