1 /* 2 * Copyright (c) 2010 Patrick McHardy <kaber@trash.net> 3 * 4 * This program is free software; you can redistribute it and/or modify 5 * it under the terms of the GNU General Public License version 2 as 6 * published by the Free Software Foundation. 7 */ 8 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 9 #include <linux/module.h> 10 #include <linux/gfp.h> 11 #include <linux/skbuff.h> 12 #include <linux/netfilter_ipv4/ip_tables.h> 13 #include <linux/netfilter_ipv6/ip6_tables.h> 14 #include <linux/netfilter/x_tables.h> 15 #include <linux/netfilter/xt_CT.h> 16 #include <net/netfilter/nf_conntrack.h> 17 #include <net/netfilter/nf_conntrack_helper.h> 18 #include <net/netfilter/nf_conntrack_ecache.h> 19 #include <net/netfilter/nf_conntrack_zones.h> 20 21 static unsigned int xt_ct_target(struct sk_buff *skb, 22 const struct xt_action_param *par) 23 { 24 const struct xt_ct_target_info *info = par->targinfo; 25 struct nf_conn *ct = info->ct; 26 27 /* Previously seen (loopback)? Ignore. */ 28 if (skb->nfct != NULL) 29 return XT_CONTINUE; 30 31 atomic_inc(&ct->ct_general.use); 32 skb->nfct = &ct->ct_general; 33 skb->nfctinfo = IP_CT_NEW; 34 35 return XT_CONTINUE; 36 } 37 38 static u8 xt_ct_find_proto(const struct xt_tgchk_param *par) 39 { 40 if (par->family == NFPROTO_IPV4) { 41 const struct ipt_entry *e = par->entryinfo; 42 43 if (e->ip.invflags & IPT_INV_PROTO) 44 return 0; 45 return e->ip.proto; 46 } else if (par->family == NFPROTO_IPV6) { 47 const struct ip6t_entry *e = par->entryinfo; 48 49 if (e->ipv6.invflags & IP6T_INV_PROTO) 50 return 0; 51 return e->ipv6.proto; 52 } else 53 return 0; 54 } 55 56 static int xt_ct_tg_check(const struct xt_tgchk_param *par) 57 { 58 struct xt_ct_target_info *info = par->targinfo; 59 struct nf_conntrack_tuple t; 60 struct nf_conn_help *help; 61 struct nf_conn *ct; 62 int ret = 0; 63 u8 proto; 64 65 if (info->flags & ~XT_CT_NOTRACK) 66 return -EINVAL; 67 68 if (info->flags & XT_CT_NOTRACK) { 69 ct = nf_ct_untracked_get(); 70 atomic_inc(&ct->ct_general.use); 71 goto out; 72 } 73 74 #ifndef CONFIG_NF_CONNTRACK_ZONES 75 if (info->zone) 76 goto err1; 77 #endif 78 79 ret = nf_ct_l3proto_try_module_get(par->family); 80 if (ret < 0) 81 goto err1; 82 83 memset(&t, 0, sizeof(t)); 84 ct = nf_conntrack_alloc(par->net, info->zone, &t, &t, GFP_KERNEL); 85 ret = PTR_ERR(ct); 86 if (IS_ERR(ct)) 87 goto err2; 88 89 ret = 0; 90 if ((info->ct_events || info->exp_events) && 91 !nf_ct_ecache_ext_add(ct, info->ct_events, info->exp_events, 92 GFP_KERNEL)) 93 goto err3; 94 95 if (info->helper[0]) { 96 ret = -ENOENT; 97 proto = xt_ct_find_proto(par); 98 if (!proto) { 99 pr_info("You must specify a L4 protocol, " 100 "and not use inversions on it.\n"); 101 goto err3; 102 } 103 104 ret = -ENOMEM; 105 help = nf_ct_helper_ext_add(ct, GFP_KERNEL); 106 if (help == NULL) 107 goto err3; 108 109 ret = -ENOENT; 110 help->helper = nf_conntrack_helper_try_module_get(info->helper, 111 par->family, 112 proto); 113 if (help->helper == NULL) { 114 pr_info("No such helper \"%s\"\n", info->helper); 115 goto err3; 116 } 117 } 118 119 __set_bit(IPS_TEMPLATE_BIT, &ct->status); 120 __set_bit(IPS_CONFIRMED_BIT, &ct->status); 121 out: 122 info->ct = ct; 123 return 0; 124 125 err3: 126 nf_conntrack_free(ct); 127 err2: 128 nf_ct_l3proto_module_put(par->family); 129 err1: 130 return ret; 131 } 132 133 static void xt_ct_tg_destroy(const struct xt_tgdtor_param *par) 134 { 135 struct xt_ct_target_info *info = par->targinfo; 136 struct nf_conn *ct = info->ct; 137 struct nf_conn_help *help; 138 139 if (!nf_ct_is_untracked(ct)) { 140 help = nfct_help(ct); 141 if (help) 142 module_put(help->helper->me); 143 144 nf_ct_l3proto_module_put(par->family); 145 } 146 nf_ct_put(info->ct); 147 } 148 149 static struct xt_target xt_ct_tg __read_mostly = { 150 .name = "CT", 151 .family = NFPROTO_UNSPEC, 152 .targetsize = sizeof(struct xt_ct_target_info), 153 .checkentry = xt_ct_tg_check, 154 .destroy = xt_ct_tg_destroy, 155 .target = xt_ct_target, 156 .table = "raw", 157 .me = THIS_MODULE, 158 }; 159 160 static int __init xt_ct_tg_init(void) 161 { 162 return xt_register_target(&xt_ct_tg); 163 } 164 165 static void __exit xt_ct_tg_exit(void) 166 { 167 xt_unregister_target(&xt_ct_tg); 168 } 169 170 module_init(xt_ct_tg_init); 171 module_exit(xt_ct_tg_exit); 172 173 MODULE_LICENSE("GPL"); 174 MODULE_DESCRIPTION("Xtables: connection tracking target"); 175 MODULE_ALIAS("ipt_CT"); 176 MODULE_ALIAS("ip6t_CT"); 177