Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 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/config.h> |
| 14 | #include <linux/module.h> |
| 15 | #include <linux/netfilter_ipv4/ip_tables.h> |
| 16 | #include <linux/netdevice.h> |
| 17 | #include <linux/skbuff.h> |
| 18 | #include <net/sock.h> |
| 19 | #include <net/route.h> |
| 20 | #include <linux/ip.h> |
| 21 | |
| 22 | MODULE_LICENSE("GPL"); |
| 23 | MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>"); |
| 24 | MODULE_DESCRIPTION("iptables mangle table"); |
| 25 | |
| 26 | #define MANGLE_VALID_HOOKS ((1 << NF_IP_PRE_ROUTING) | \ |
| 27 | (1 << NF_IP_LOCAL_IN) | \ |
| 28 | (1 << NF_IP_FORWARD) | \ |
| 29 | (1 << NF_IP_LOCAL_OUT) | \ |
| 30 | (1 << NF_IP_POST_ROUTING)) |
| 31 | |
| 32 | /* Ouch - five different hooks? Maybe this should be a config option..... -- BC */ |
| 33 | static struct |
| 34 | { |
| 35 | struct ipt_replace repl; |
| 36 | struct ipt_standard entries[5]; |
| 37 | struct ipt_error term; |
| 38 | } initial_table __initdata |
| 39 | = { { "mangle", MANGLE_VALID_HOOKS, 6, |
| 40 | sizeof(struct ipt_standard) * 5 + sizeof(struct ipt_error), |
| 41 | { [NF_IP_PRE_ROUTING] = 0, |
| 42 | [NF_IP_LOCAL_IN] = sizeof(struct ipt_standard), |
| 43 | [NF_IP_FORWARD] = sizeof(struct ipt_standard) * 2, |
| 44 | [NF_IP_LOCAL_OUT] = sizeof(struct ipt_standard) * 3, |
| 45 | [NF_IP_POST_ROUTING] = sizeof(struct ipt_standard) * 4 }, |
| 46 | { [NF_IP_PRE_ROUTING] = 0, |
| 47 | [NF_IP_LOCAL_IN] = sizeof(struct ipt_standard), |
| 48 | [NF_IP_FORWARD] = sizeof(struct ipt_standard) * 2, |
| 49 | [NF_IP_LOCAL_OUT] = sizeof(struct ipt_standard) * 3, |
| 50 | [NF_IP_POST_ROUTING] = sizeof(struct ipt_standard) * 4 }, |
| 51 | 0, NULL, { } }, |
| 52 | { |
| 53 | /* PRE_ROUTING */ |
| 54 | { { { { 0 }, { 0 }, { 0 }, { 0 }, "", "", { 0 }, { 0 }, 0, 0, 0 }, |
| 55 | 0, |
| 56 | sizeof(struct ipt_entry), |
| 57 | sizeof(struct ipt_standard), |
| 58 | 0, { 0, 0 }, { } }, |
| 59 | { { { { IPT_ALIGN(sizeof(struct ipt_standard_target)), "" } }, { } }, |
| 60 | -NF_ACCEPT - 1 } }, |
| 61 | /* LOCAL_IN */ |
| 62 | { { { { 0 }, { 0 }, { 0 }, { 0 }, "", "", { 0 }, { 0 }, 0, 0, 0 }, |
| 63 | 0, |
| 64 | sizeof(struct ipt_entry), |
| 65 | sizeof(struct ipt_standard), |
| 66 | 0, { 0, 0 }, { } }, |
| 67 | { { { { IPT_ALIGN(sizeof(struct ipt_standard_target)), "" } }, { } }, |
| 68 | -NF_ACCEPT - 1 } }, |
| 69 | /* FORWARD */ |
| 70 | { { { { 0 }, { 0 }, { 0 }, { 0 }, "", "", { 0 }, { 0 }, 0, 0, 0 }, |
| 71 | 0, |
| 72 | sizeof(struct ipt_entry), |
| 73 | sizeof(struct ipt_standard), |
| 74 | 0, { 0, 0 }, { } }, |
| 75 | { { { { IPT_ALIGN(sizeof(struct ipt_standard_target)), "" } }, { } }, |
| 76 | -NF_ACCEPT - 1 } }, |
| 77 | /* LOCAL_OUT */ |
| 78 | { { { { 0 }, { 0 }, { 0 }, { 0 }, "", "", { 0 }, { 0 }, 0, 0, 0 }, |
| 79 | 0, |
| 80 | sizeof(struct ipt_entry), |
| 81 | sizeof(struct ipt_standard), |
| 82 | 0, { 0, 0 }, { } }, |
| 83 | { { { { IPT_ALIGN(sizeof(struct ipt_standard_target)), "" } }, { } }, |
| 84 | -NF_ACCEPT - 1 } }, |
| 85 | /* POST_ROUTING */ |
| 86 | { { { { 0 }, { 0 }, { 0 }, { 0 }, "", "", { 0 }, { 0 }, 0, 0, 0 }, |
| 87 | 0, |
| 88 | sizeof(struct ipt_entry), |
| 89 | sizeof(struct ipt_standard), |
| 90 | 0, { 0, 0 }, { } }, |
| 91 | { { { { IPT_ALIGN(sizeof(struct ipt_standard_target)), "" } }, { } }, |
| 92 | -NF_ACCEPT - 1 } }, |
| 93 | }, |
| 94 | /* ERROR */ |
| 95 | { { { { 0 }, { 0 }, { 0 }, { 0 }, "", "", { 0 }, { 0 }, 0, 0, 0 }, |
| 96 | 0, |
| 97 | sizeof(struct ipt_entry), |
| 98 | sizeof(struct ipt_error), |
| 99 | 0, { 0, 0 }, { } }, |
| 100 | { { { { IPT_ALIGN(sizeof(struct ipt_error_target)), IPT_ERROR_TARGET } }, |
| 101 | { } }, |
| 102 | "ERROR" |
| 103 | } |
| 104 | } |
| 105 | }; |
| 106 | |
| 107 | static struct ipt_table packet_mangler = { |
| 108 | .name = "mangle", |
| 109 | .valid_hooks = MANGLE_VALID_HOOKS, |
| 110 | .lock = RW_LOCK_UNLOCKED, |
| 111 | .me = THIS_MODULE, |
| 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, NULL); |
| 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 | u_int32_t saddr, daddr; |
| 135 | unsigned long nfmark; |
| 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 | nfmark = (*pskb)->nfmark; |
| 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, NULL); |
| 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 | #ifdef CONFIG_IP_ROUTE_FWMARK |
| 157 | || (*pskb)->nfmark != nfmark |
| 158 | #endif |
| 159 | || (*pskb)->nh.iph->tos != tos)) |
| 160 | return ip_route_me_harder(pskb) == 0 ? ret : NF_DROP; |
| 161 | |
| 162 | return ret; |
| 163 | } |
| 164 | |
| 165 | static struct nf_hook_ops ipt_ops[] = { |
| 166 | { |
| 167 | .hook = ipt_route_hook, |
| 168 | .owner = THIS_MODULE, |
| 169 | .pf = PF_INET, |
| 170 | .hooknum = NF_IP_PRE_ROUTING, |
| 171 | .priority = NF_IP_PRI_MANGLE, |
| 172 | }, |
| 173 | { |
| 174 | .hook = ipt_route_hook, |
| 175 | .owner = THIS_MODULE, |
| 176 | .pf = PF_INET, |
| 177 | .hooknum = NF_IP_LOCAL_IN, |
| 178 | .priority = NF_IP_PRI_MANGLE, |
| 179 | }, |
| 180 | { |
| 181 | .hook = ipt_route_hook, |
| 182 | .owner = THIS_MODULE, |
| 183 | .pf = PF_INET, |
| 184 | .hooknum = NF_IP_FORWARD, |
| 185 | .priority = NF_IP_PRI_MANGLE, |
| 186 | }, |
| 187 | { |
| 188 | .hook = ipt_local_hook, |
| 189 | .owner = THIS_MODULE, |
| 190 | .pf = PF_INET, |
| 191 | .hooknum = NF_IP_LOCAL_OUT, |
| 192 | .priority = NF_IP_PRI_MANGLE, |
| 193 | }, |
| 194 | { |
| 195 | .hook = ipt_route_hook, |
| 196 | .owner = THIS_MODULE, |
| 197 | .pf = PF_INET, |
| 198 | .hooknum = NF_IP_POST_ROUTING, |
| 199 | .priority = NF_IP_PRI_MANGLE, |
| 200 | }, |
| 201 | }; |
| 202 | |
| 203 | static int __init init(void) |
| 204 | { |
| 205 | int ret; |
| 206 | |
| 207 | /* Register table */ |
| 208 | ret = ipt_register_table(&packet_mangler, &initial_table.repl); |
| 209 | if (ret < 0) |
| 210 | return ret; |
| 211 | |
| 212 | /* Register hooks */ |
| 213 | ret = nf_register_hook(&ipt_ops[0]); |
| 214 | if (ret < 0) |
| 215 | goto cleanup_table; |
| 216 | |
| 217 | ret = nf_register_hook(&ipt_ops[1]); |
| 218 | if (ret < 0) |
| 219 | goto cleanup_hook0; |
| 220 | |
| 221 | ret = nf_register_hook(&ipt_ops[2]); |
| 222 | if (ret < 0) |
| 223 | goto cleanup_hook1; |
| 224 | |
| 225 | ret = nf_register_hook(&ipt_ops[3]); |
| 226 | if (ret < 0) |
| 227 | goto cleanup_hook2; |
| 228 | |
| 229 | ret = nf_register_hook(&ipt_ops[4]); |
| 230 | if (ret < 0) |
| 231 | goto cleanup_hook3; |
| 232 | |
| 233 | return ret; |
| 234 | |
| 235 | cleanup_hook3: |
| 236 | nf_unregister_hook(&ipt_ops[3]); |
| 237 | cleanup_hook2: |
| 238 | nf_unregister_hook(&ipt_ops[2]); |
| 239 | cleanup_hook1: |
| 240 | nf_unregister_hook(&ipt_ops[1]); |
| 241 | cleanup_hook0: |
| 242 | nf_unregister_hook(&ipt_ops[0]); |
| 243 | cleanup_table: |
| 244 | ipt_unregister_table(&packet_mangler); |
| 245 | |
| 246 | return ret; |
| 247 | } |
| 248 | |
| 249 | static void __exit fini(void) |
| 250 | { |
| 251 | unsigned int i; |
| 252 | |
| 253 | for (i = 0; i < sizeof(ipt_ops)/sizeof(struct nf_hook_ops); i++) |
| 254 | nf_unregister_hook(&ipt_ops[i]); |
| 255 | |
| 256 | ipt_unregister_table(&packet_mangler); |
| 257 | } |
| 258 | |
| 259 | module_init(init); |
| 260 | module_exit(fini); |