1/* This kernel module is used to modify the connection mark values, or
2 * to optionally restore the skb nfmark from the connection mark
3 *
4 * Copyright (C) 2002,2004 MARA Systems AB <http://www.marasystems.com>
5 * by Henrik Nordstrom <hno@marasystems.com>
6 *
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License as published by
9 * the Free Software Foundation; either version 2 of the License, or
10 * (at your option) any later version.
11 *
12 * This program is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
15 * GNU General Public License for more details.
16 *
17 * You should have received a copy of the GNU General Public License
18 * along with this program; if not, write to the Free Software
19 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
20 */
21#include <linux/module.h>
22#include <linux/skbuff.h>
23#include <linux/ip.h>
24#include <net/checksum.h>
25
26MODULE_AUTHOR("Henrik Nordstrom <hno@marasytems.com>");
27MODULE_DESCRIPTION("IP tables CONNMARK matching module");
28MODULE_LICENSE("GPL");
29MODULE_ALIAS("ipt_CONNMARK");
30
31#include <linux/netfilter/x_tables.h>
32#include <linux/netfilter/xt_CONNMARK.h>
33#include <net/netfilter/nf_conntrack_ecache.h>
34
35static unsigned int
36target(struct sk_buff **pskb,
37       const struct net_device *in,
38       const struct net_device *out,
39       unsigned int hooknum,
40       const struct xt_target *target,
41       const void *targinfo)
42{
43	const struct xt_connmark_target_info *markinfo = targinfo;
44	struct nf_conn *ct;
45	enum ip_conntrack_info ctinfo;
46	u_int32_t diff;
47	u_int32_t mark;
48	u_int32_t newmark;
49
50	ct = nf_ct_get(*pskb, &ctinfo);
51	if (ct) {
52		switch(markinfo->mode) {
53		case XT_CONNMARK_SET:
54			newmark = (ct->mark & ~markinfo->mask) | markinfo->mark;
55			if (newmark != ct->mark) {
56				ct->mark = newmark;
57				nf_conntrack_event_cache(IPCT_MARK, *pskb);
58			}
59			break;
60		case XT_CONNMARK_SAVE:
61			newmark = (ct->mark & ~markinfo->mask) |
62				  ((*pskb)->mark & markinfo->mask);
63			if (ct->mark != newmark) {
64				ct->mark = newmark;
65				nf_conntrack_event_cache(IPCT_MARK, *pskb);
66			}
67			break;
68		case XT_CONNMARK_RESTORE:
69			mark = (*pskb)->mark;
70			diff = (ct->mark ^ mark) & markinfo->mask;
71			(*pskb)->mark = mark ^ diff;
72			break;
73		}
74	}
75
76	return XT_CONTINUE;
77}
78
79static int
80checkentry(const char *tablename,
81	   const void *entry,
82	   const struct xt_target *target,
83	   void *targinfo,
84	   unsigned int hook_mask)
85{
86	struct xt_connmark_target_info *matchinfo = targinfo;
87
88	if (nf_ct_l3proto_try_module_get(target->family) < 0) {
89		printk(KERN_WARNING "can't load conntrack support for "
90				    "proto=%d\n", target->family);
91		return 0;
92	}
93	if (matchinfo->mode == XT_CONNMARK_RESTORE) {
94		if (strcmp(tablename, "mangle") != 0) {
95			printk(KERN_WARNING "CONNMARK: restore can only be "
96			       "called from \"mangle\" table, not \"%s\"\n",
97			       tablename);
98			return 0;
99		}
100	}
101	if (matchinfo->mark > 0xffffffff || matchinfo->mask > 0xffffffff) {
102		printk(KERN_WARNING "CONNMARK: Only supports 32bit mark\n");
103		return 0;
104	}
105	return 1;
106}
107
108static void
109destroy(const struct xt_target *target, void *targinfo)
110{
111	nf_ct_l3proto_module_put(target->family);
112}
113
114#ifdef CONFIG_COMPAT
115struct compat_xt_connmark_target_info {
116	compat_ulong_t	mark, mask;
117	u_int8_t	mode;
118	u_int8_t	__pad1;
119	u_int16_t	__pad2;
120};
121
122static void compat_from_user(void *dst, void *src)
123{
124	struct compat_xt_connmark_target_info *cm = src;
125	struct xt_connmark_target_info m = {
126		.mark	= cm->mark,
127		.mask	= cm->mask,
128		.mode	= cm->mode,
129	};
130	memcpy(dst, &m, sizeof(m));
131}
132
133static int compat_to_user(void __user *dst, void *src)
134{
135	struct xt_connmark_target_info *m = src;
136	struct compat_xt_connmark_target_info cm = {
137		.mark	= m->mark,
138		.mask	= m->mask,
139		.mode	= m->mode,
140	};
141	return copy_to_user(dst, &cm, sizeof(cm)) ? -EFAULT : 0;
142}
143#endif /* CONFIG_COMPAT */
144
145static struct xt_target xt_connmark_target[] = {
146	{
147		.name		= "CONNMARK",
148		.family		= AF_INET,
149		.checkentry	= checkentry,
150		.destroy	= destroy,
151		.target		= target,
152		.targetsize	= sizeof(struct xt_connmark_target_info),
153#ifdef CONFIG_COMPAT
154		.compatsize	= sizeof(struct compat_xt_connmark_target_info),
155		.compat_from_user = compat_from_user,
156		.compat_to_user	= compat_to_user,
157#endif
158		.me		= THIS_MODULE
159	},
160	{
161		.name		= "CONNMARK",
162		.family		= AF_INET6,
163		.checkentry	= checkentry,
164		.destroy	= destroy,
165		.target		= target,
166		.targetsize	= sizeof(struct xt_connmark_target_info),
167		.me		= THIS_MODULE
168	},
169};
170
171static int __init xt_connmark_init(void)
172{
173	return xt_register_targets(xt_connmark_target,
174				   ARRAY_SIZE(xt_connmark_target));
175}
176
177static void __exit xt_connmark_fini(void)
178{
179	xt_unregister_targets(xt_connmark_target,
180			      ARRAY_SIZE(xt_connmark_target));
181}
182
183module_init(xt_connmark_init);
184module_exit(xt_connmark_fini);
185