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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 | /* * This is the 1999 rewrite of IP Firewalling, aiming for kernel 2.3.x. * * Copyright (C) 1999 Paul `Rusty' Russell & Michael J. Neuling */ #include <linux/module.h> #include <linux/netfilter_ipv4/ip_tables.h> #define FILTER_VALID_HOOKS ((1 << NF_IP_LOCAL_IN) | (1 << NF_IP_FORWARD) | (1 << NF_IP_LOCAL_OUT)) /* Standard entry. */ struct ipt_standard { struct ipt_entry entry; struct ipt_standard_target target; }; struct ipt_error_target { struct ipt_entry_target target; char errorname[IPT_FUNCTION_MAXNAMELEN]; }; struct ipt_error { struct ipt_entry entry; struct ipt_error_target target; }; static struct { struct ipt_replace repl; struct ipt_standard entries[3]; struct ipt_error term; } initial_table __initdata = { { "filter", FILTER_VALID_HOOKS, 4, sizeof(struct ipt_standard) * 3 + sizeof(struct ipt_error), { [NF_IP_LOCAL_IN] 0, [NF_IP_FORWARD] sizeof(struct ipt_standard), [NF_IP_LOCAL_OUT] sizeof(struct ipt_standard) * 2 }, { [NF_IP_LOCAL_IN] 0, [NF_IP_FORWARD] sizeof(struct ipt_standard), [NF_IP_LOCAL_OUT] sizeof(struct ipt_standard) * 2 }, 0, NULL, { } }, { /* LOCAL_IN */ { { { { 0 }, { 0 }, { 0 }, { 0 }, "", "", { 0 }, { 0 }, 0, 0, 0 }, 0, sizeof(struct ipt_entry), sizeof(struct ipt_standard), 0, { 0, 0 }, { } }, { { { { IPT_ALIGN(sizeof(struct ipt_standard_target)), "" } }, { } }, -NF_ACCEPT - 1 } }, /* FORWARD */ { { { { 0 }, { 0 }, { 0 }, { 0 }, "", "", { 0 }, { 0 }, 0, 0, 0 }, 0, sizeof(struct ipt_entry), sizeof(struct ipt_standard), 0, { 0, 0 }, { } }, { { { { IPT_ALIGN(sizeof(struct ipt_standard_target)), "" } }, { } }, -NF_ACCEPT - 1 } }, /* LOCAL_OUT */ { { { { 0 }, { 0 }, { 0 }, { 0 }, "", "", { 0 }, { 0 }, 0, 0, 0 }, 0, sizeof(struct ipt_entry), sizeof(struct ipt_standard), 0, { 0, 0 }, { } }, { { { { IPT_ALIGN(sizeof(struct ipt_standard_target)), "" } }, { } }, -NF_ACCEPT - 1 } } }, /* ERROR */ { { { { 0 }, { 0 }, { 0 }, { 0 }, "", "", { 0 }, { 0 }, 0, 0, 0 }, 0, sizeof(struct ipt_entry), sizeof(struct ipt_error), 0, { 0, 0 }, { } }, { { { { IPT_ALIGN(sizeof(struct ipt_error_target)), IPT_ERROR_TARGET } }, { } }, "ERROR" } } }; static struct ipt_table packet_filter = { { NULL, NULL }, "filter", &initial_table.repl, FILTER_VALID_HOOKS, RW_LOCK_UNLOCKED, NULL }; /* The work comes in here from netfilter.c. */ static unsigned int ipt_hook(unsigned int hook, struct sk_buff **pskb, const struct net_device *in, const struct net_device *out, int (*okfn)(struct sk_buff *)) { return ipt_do_table(pskb, hook, in, out, &packet_filter, NULL); } static unsigned int ipt_local_out_hook(unsigned int hook, struct sk_buff **pskb, const struct net_device *in, const struct net_device *out, int (*okfn)(struct sk_buff *)) { /* root is playing with raw sockets. */ if ((*pskb)->len < sizeof(struct iphdr) || (*pskb)->nh.iph->ihl * 4 < sizeof(struct iphdr)) { if (net_ratelimit()) printk("ipt_hook: happy cracking.\n"); return NF_ACCEPT; } return ipt_do_table(pskb, hook, in, out, &packet_filter, NULL); } static struct nf_hook_ops ipt_ops[] = { { { NULL, NULL }, ipt_hook, PF_INET, NF_IP_LOCAL_IN, NF_IP_PRI_FILTER }, { { NULL, NULL }, ipt_hook, PF_INET, NF_IP_FORWARD, NF_IP_PRI_FILTER }, { { NULL, NULL }, ipt_local_out_hook, PF_INET, NF_IP_LOCAL_OUT, NF_IP_PRI_FILTER } }; /* Default to forward because I got too much mail already. */ static int forward = NF_ACCEPT; MODULE_PARM(forward, "i"); static int __init init(void) { int ret; if (forward < 0 || forward > NF_MAX_VERDICT) { printk("iptables forward must be 0 or 1\n"); return -EINVAL; } /* Entry 1 is the FORWARD hook */ initial_table.entries[1].target.verdict = -forward - 1; /* Register table */ ret = ipt_register_table(&packet_filter); if (ret < 0) return ret; /* Register hooks */ ret = nf_register_hook(&ipt_ops[0]); if (ret < 0) goto cleanup_table; ret = nf_register_hook(&ipt_ops[1]); if (ret < 0) goto cleanup_hook0; ret = nf_register_hook(&ipt_ops[2]); if (ret < 0) goto cleanup_hook1; return ret; cleanup_hook1: nf_unregister_hook(&ipt_ops[1]); cleanup_hook0: nf_unregister_hook(&ipt_ops[0]); cleanup_table: ipt_unregister_table(&packet_filter); return ret; } static void __exit fini(void) { unsigned int i; for (i = 0; i < sizeof(ipt_ops)/sizeof(struct nf_hook_ops); i++) nf_unregister_hook(&ipt_ops[i]); ipt_unregister_table(&packet_filter); } module_init(init); module_exit(fini); |