[NET]: Rethink mark field in struct flowi
[linux-2.6.git] / net / ipv4 / netfilter / iptable_mangle.c
1 /*
2  * This is the 1999 rewrite of IP Firewalling, aiming for kernel 2.3.x.
3  *
4  * Copyright (C) 1999 Paul `Rusty' Russell & Michael J. Neuling
5  * Copyright (C) 2000-2004 Netfilter Core Team <coreteam@netfilter.org>
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 version 2 as
9  * published by the Free Software Foundation.
10  *
11  * Extended to all five netfilter hooks by Brad Chapman & Harald Welte
12  */
13 #include <linux/module.h>
14 #include <linux/netfilter_ipv4/ip_tables.h>
15 #include <linux/netdevice.h>
16 #include <linux/skbuff.h>
17 #include <net/sock.h>
18 #include <net/route.h>
19 #include <linux/ip.h>
20
21 MODULE_LICENSE("GPL");
22 MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>");
23 MODULE_DESCRIPTION("iptables mangle table");
24
25 #define MANGLE_VALID_HOOKS ((1 << NF_IP_PRE_ROUTING) | \
26                             (1 << NF_IP_LOCAL_IN) | \
27                             (1 << NF_IP_FORWARD) | \
28                             (1 << NF_IP_LOCAL_OUT) | \
29                             (1 << NF_IP_POST_ROUTING))
30
31 /* Ouch - five different hooks? Maybe this should be a config option..... -- BC */
32 static struct
33 {
34         struct ipt_replace repl;
35         struct ipt_standard entries[5];
36         struct ipt_error term;
37 } initial_table __initdata
38 = { { "mangle", MANGLE_VALID_HOOKS, 6,
39       sizeof(struct ipt_standard) * 5 + sizeof(struct ipt_error),
40       { [NF_IP_PRE_ROUTING]     = 0,
41         [NF_IP_LOCAL_IN]        = sizeof(struct ipt_standard),
42         [NF_IP_FORWARD]         = sizeof(struct ipt_standard) * 2,
43         [NF_IP_LOCAL_OUT]       = sizeof(struct ipt_standard) * 3,
44         [NF_IP_POST_ROUTING]    = sizeof(struct ipt_standard) * 4 },
45       { [NF_IP_PRE_ROUTING]     = 0,
46         [NF_IP_LOCAL_IN]        = sizeof(struct ipt_standard),
47         [NF_IP_FORWARD]         = sizeof(struct ipt_standard) * 2,
48         [NF_IP_LOCAL_OUT]       = sizeof(struct ipt_standard) * 3,
49         [NF_IP_POST_ROUTING]    = sizeof(struct ipt_standard) * 4 },
50       0, NULL, { } },
51     {
52             /* PRE_ROUTING */
53             { { { { 0 }, { 0 }, { 0 }, { 0 }, "", "", { 0 }, { 0 }, 0, 0, 0 },
54                 0,
55                 sizeof(struct ipt_entry),
56                 sizeof(struct ipt_standard),
57                 0, { 0, 0 }, { } },
58               { { { { IPT_ALIGN(sizeof(struct ipt_standard_target)), "" } }, { } },
59                 -NF_ACCEPT - 1 } },
60             /* LOCAL_IN */
61             { { { { 0 }, { 0 }, { 0 }, { 0 }, "", "", { 0 }, { 0 }, 0, 0, 0 },
62                 0,
63                 sizeof(struct ipt_entry),
64                 sizeof(struct ipt_standard),
65                 0, { 0, 0 }, { } },
66               { { { { IPT_ALIGN(sizeof(struct ipt_standard_target)), "" } }, { } },
67                 -NF_ACCEPT - 1 } },
68             /* FORWARD */
69             { { { { 0 }, { 0 }, { 0 }, { 0 }, "", "", { 0 }, { 0 }, 0, 0, 0 },
70                 0,
71                 sizeof(struct ipt_entry),
72                 sizeof(struct ipt_standard),
73                 0, { 0, 0 }, { } },
74               { { { { IPT_ALIGN(sizeof(struct ipt_standard_target)), "" } }, { } },
75                 -NF_ACCEPT - 1 } },
76             /* LOCAL_OUT */
77             { { { { 0 }, { 0 }, { 0 }, { 0 }, "", "", { 0 }, { 0 }, 0, 0, 0 },
78                 0,
79                 sizeof(struct ipt_entry),
80                 sizeof(struct ipt_standard),
81                 0, { 0, 0 }, { } },
82               { { { { IPT_ALIGN(sizeof(struct ipt_standard_target)), "" } }, { } },
83                 -NF_ACCEPT - 1 } },
84             /* POST_ROUTING */
85             { { { { 0 }, { 0 }, { 0 }, { 0 }, "", "", { 0 }, { 0 }, 0, 0, 0 },
86                 0,
87                 sizeof(struct ipt_entry),
88                 sizeof(struct ipt_standard),
89                 0, { 0, 0 }, { } },
90               { { { { IPT_ALIGN(sizeof(struct ipt_standard_target)), "" } }, { } },
91                 -NF_ACCEPT - 1 } },
92     },
93     /* ERROR */
94     { { { { 0 }, { 0 }, { 0 }, { 0 }, "", "", { 0 }, { 0 }, 0, 0, 0 },
95         0,
96         sizeof(struct ipt_entry),
97         sizeof(struct ipt_error),
98         0, { 0, 0 }, { } },
99       { { { { IPT_ALIGN(sizeof(struct ipt_error_target)), IPT_ERROR_TARGET } },
100           { } },
101         "ERROR"
102       }
103     }
104 };
105
106 static struct ipt_table packet_mangler = {
107         .name           = "mangle",
108         .valid_hooks    = MANGLE_VALID_HOOKS,
109         .lock           = RW_LOCK_UNLOCKED,
110         .me             = THIS_MODULE,
111         .af             = AF_INET,
112 };
113
114 /* The work comes in here from netfilter.c. */
115 static unsigned int
116 ipt_route_hook(unsigned int hook,
117          struct sk_buff **pskb,
118          const struct net_device *in,
119          const struct net_device *out,
120          int (*okfn)(struct sk_buff *))
121 {
122         return ipt_do_table(pskb, hook, in, out, &packet_mangler);
123 }
124
125 static unsigned int
126 ipt_local_hook(unsigned int hook,
127                    struct sk_buff **pskb,
128                    const struct net_device *in,
129                    const struct net_device *out,
130                    int (*okfn)(struct sk_buff *))
131 {
132         unsigned int ret;
133         u_int8_t tos;
134         __be32 saddr, daddr;
135         u_int32_t mark;
136
137         /* root is playing with raw sockets. */
138         if ((*pskb)->len < sizeof(struct iphdr)
139             || (*pskb)->nh.iph->ihl * 4 < sizeof(struct iphdr)) {
140                 if (net_ratelimit())
141                         printk("ipt_hook: happy cracking.\n");
142                 return NF_ACCEPT;
143         }
144
145         /* Save things which could affect route */
146         mark = (*pskb)->mark;
147         saddr = (*pskb)->nh.iph->saddr;
148         daddr = (*pskb)->nh.iph->daddr;
149         tos = (*pskb)->nh.iph->tos;
150
151         ret = ipt_do_table(pskb, hook, in, out, &packet_mangler);
152         /* Reroute for ANY change. */
153         if (ret != NF_DROP && ret != NF_STOLEN && ret != NF_QUEUE
154             && ((*pskb)->nh.iph->saddr != saddr
155                 || (*pskb)->nh.iph->daddr != daddr
156                 || (*pskb)->mark != mark
157                 || (*pskb)->nh.iph->tos != tos))
158                 if (ip_route_me_harder(pskb, RTN_UNSPEC))
159                         ret = NF_DROP;
160
161         return ret;
162 }
163
164 static struct nf_hook_ops ipt_ops[] = {
165         {
166                 .hook           = ipt_route_hook,
167                 .owner          = THIS_MODULE,
168                 .pf             = PF_INET,
169                 .hooknum        = NF_IP_PRE_ROUTING, 
170                 .priority       = NF_IP_PRI_MANGLE,
171         },
172         {
173                 .hook           = ipt_route_hook,
174                 .owner          = THIS_MODULE,
175                 .pf             = PF_INET,
176                 .hooknum        = NF_IP_LOCAL_IN,
177                 .priority       = NF_IP_PRI_MANGLE,
178         },
179         {
180                 .hook           = ipt_route_hook,
181                 .owner          = THIS_MODULE,
182                 .pf             = PF_INET,
183                 .hooknum        = NF_IP_FORWARD,
184                 .priority       = NF_IP_PRI_MANGLE,
185         },
186         {
187                 .hook           = ipt_local_hook,
188                 .owner          = THIS_MODULE,
189                 .pf             = PF_INET,
190                 .hooknum        = NF_IP_LOCAL_OUT,
191                 .priority       = NF_IP_PRI_MANGLE,
192         },
193         {
194                 .hook           = ipt_route_hook,
195                 .owner          = THIS_MODULE,
196                 .pf             = PF_INET,
197                 .hooknum        = NF_IP_POST_ROUTING,
198                 .priority       = NF_IP_PRI_MANGLE,
199         },
200 };
201
202 static int __init iptable_mangle_init(void)
203 {
204         int ret;
205
206         /* Register table */
207         ret = ipt_register_table(&packet_mangler, &initial_table.repl);
208         if (ret < 0)
209                 return ret;
210
211         /* Register hooks */
212         ret = nf_register_hooks(ipt_ops, ARRAY_SIZE(ipt_ops));
213         if (ret < 0)
214                 goto cleanup_table;
215
216         return ret;
217
218  cleanup_table:
219         ipt_unregister_table(&packet_mangler);
220         return ret;
221 }
222
223 static void __exit iptable_mangle_fini(void)
224 {
225         nf_unregister_hooks(ipt_ops, ARRAY_SIZE(ipt_ops));
226         ipt_unregister_table(&packet_mangler);
227 }
228
229 module_init(iptable_mangle_init);
230 module_exit(iptable_mangle_fini);