8cc324b159e9b30d55b735eb9ae377df2a0b193e
[linux-2.6.git] / net / netfilter / xt_CONNMARK.c
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
26 MODULE_AUTHOR("Henrik Nordstrom <hno@marasytems.com>");
27 MODULE_DESCRIPTION("IP tables CONNMARK matching module");
28 MODULE_LICENSE("GPL");
29 MODULE_ALIAS("ipt_CONNMARK");
30 MODULE_ALIAS("ip6t_CONNMARK");
31
32 #include <linux/netfilter/x_tables.h>
33 #include <linux/netfilter/xt_CONNMARK.h>
34 #include <net/netfilter/nf_conntrack_ecache.h>
35
36 static unsigned int
37 target(struct sk_buff *skb,
38        const struct net_device *in,
39        const struct net_device *out,
40        unsigned int hooknum,
41        const struct xt_target *target,
42        const void *targinfo)
43 {
44         const struct xt_connmark_target_info *markinfo = targinfo;
45         struct nf_conn *ct;
46         enum ip_conntrack_info ctinfo;
47         u_int32_t diff;
48         u_int32_t mark;
49         u_int32_t newmark;
50
51         ct = nf_ct_get(skb, &ctinfo);
52         if (ct) {
53                 switch(markinfo->mode) {
54                 case XT_CONNMARK_SET:
55                         newmark = (ct->mark & ~markinfo->mask) | markinfo->mark;
56                         if (newmark != ct->mark) {
57                                 ct->mark = newmark;
58                                 nf_conntrack_event_cache(IPCT_MARK, skb);
59                         }
60                         break;
61                 case XT_CONNMARK_SAVE:
62                         newmark = (ct->mark & ~markinfo->mask) |
63                                   (skb->mark & markinfo->mask);
64                         if (ct->mark != newmark) {
65                                 ct->mark = newmark;
66                                 nf_conntrack_event_cache(IPCT_MARK, skb);
67                         }
68                         break;
69                 case XT_CONNMARK_RESTORE:
70                         mark = skb->mark;
71                         diff = (ct->mark ^ mark) & markinfo->mask;
72                         skb->mark = mark ^ diff;
73                         break;
74                 }
75         }
76
77         return XT_CONTINUE;
78 }
79
80 static bool
81 checkentry(const char *tablename,
82            const void *entry,
83            const struct xt_target *target,
84            void *targinfo,
85            unsigned int hook_mask)
86 {
87         const struct xt_connmark_target_info *matchinfo = targinfo;
88
89         if (nf_ct_l3proto_try_module_get(target->family) < 0) {
90                 printk(KERN_WARNING "can't load conntrack support for "
91                                     "proto=%d\n", target->family);
92                 return false;
93         }
94         if (matchinfo->mode == XT_CONNMARK_RESTORE) {
95                 if (strcmp(tablename, "mangle") != 0) {
96                         printk(KERN_WARNING "CONNMARK: restore can only be "
97                                "called from \"mangle\" table, not \"%s\"\n",
98                                tablename);
99                         return false;
100                 }
101         }
102         if (matchinfo->mark > 0xffffffff || matchinfo->mask > 0xffffffff) {
103                 printk(KERN_WARNING "CONNMARK: Only supports 32bit mark\n");
104                 return false;
105         }
106         return true;
107 }
108
109 static void
110 destroy(const struct xt_target *target, void *targinfo)
111 {
112         nf_ct_l3proto_module_put(target->family);
113 }
114
115 #ifdef CONFIG_COMPAT
116 struct compat_xt_connmark_target_info {
117         compat_ulong_t  mark, mask;
118         u_int8_t        mode;
119         u_int8_t        __pad1;
120         u_int16_t       __pad2;
121 };
122
123 static void compat_from_user(void *dst, void *src)
124 {
125         const struct compat_xt_connmark_target_info *cm = src;
126         struct xt_connmark_target_info m = {
127                 .mark   = cm->mark,
128                 .mask   = cm->mask,
129                 .mode   = cm->mode,
130         };
131         memcpy(dst, &m, sizeof(m));
132 }
133
134 static int compat_to_user(void __user *dst, void *src)
135 {
136         const struct xt_connmark_target_info *m = src;
137         struct compat_xt_connmark_target_info cm = {
138                 .mark   = m->mark,
139                 .mask   = m->mask,
140                 .mode   = m->mode,
141         };
142         return copy_to_user(dst, &cm, sizeof(cm)) ? -EFAULT : 0;
143 }
144 #endif /* CONFIG_COMPAT */
145
146 static struct xt_target xt_connmark_target[] __read_mostly = {
147         {
148                 .name           = "CONNMARK",
149                 .family         = AF_INET,
150                 .checkentry     = checkentry,
151                 .destroy        = destroy,
152                 .target         = target,
153                 .targetsize     = sizeof(struct xt_connmark_target_info),
154 #ifdef CONFIG_COMPAT
155                 .compatsize     = sizeof(struct compat_xt_connmark_target_info),
156                 .compat_from_user = compat_from_user,
157                 .compat_to_user = compat_to_user,
158 #endif
159                 .me             = THIS_MODULE
160         },
161         {
162                 .name           = "CONNMARK",
163                 .family         = AF_INET6,
164                 .checkentry     = checkentry,
165                 .destroy        = destroy,
166                 .target         = target,
167                 .targetsize     = sizeof(struct xt_connmark_target_info),
168                 .me             = THIS_MODULE
169         },
170 };
171
172 static int __init xt_connmark_init(void)
173 {
174         return xt_register_targets(xt_connmark_target,
175                                    ARRAY_SIZE(xt_connmark_target));
176 }
177
178 static void __exit xt_connmark_fini(void)
179 {
180         xt_unregister_targets(xt_connmark_target,
181                               ARRAY_SIZE(xt_connmark_target));
182 }
183
184 module_init(xt_connmark_init);
185 module_exit(xt_connmark_fini);