1 /* Netfilter messages via netlink socket. Allows for user space 2 * protocol helpers and general trouble making from userspace. 3 * 4 * (C) 2001 by Jay Schulist <jschlst@samba.org>, 5 * (C) 2002-2005 by Harald Welte <laforge@gnumonks.org> 6 * (C) 2005,2007 by Pablo Neira Ayuso <pablo@netfilter.org> 7 * 8 * Initial netfilter messages via netlink development funded and 9 * generally made possible by Network Robots, Inc. (www.networkrobots.com) 10 * 11 * Further development of this code funded by Astaro AG (http://www.astaro.com) 12 * 13 * This software may be used and distributed according to the terms 14 * of the GNU General Public License, incorporated herein by reference. 15 */ 16 17 #include <linux/module.h> 18 #include <linux/types.h> 19 #include <linux/socket.h> 20 #include <linux/kernel.h> 21 #include <linux/major.h> 22 #include <linux/timer.h> 23 #include <linux/string.h> 24 #include <linux/sockios.h> 25 #include <linux/net.h> 26 #include <linux/fcntl.h> 27 #include <linux/skbuff.h> 28 #include <asm/uaccess.h> 29 #include <asm/system.h> 30 #include <net/sock.h> 31 #include <net/netlink.h> 32 #include <linux/init.h> 33 34 #include <linux/netlink.h> 35 #include <linux/netfilter/nfnetlink.h> 36 37 MODULE_LICENSE("GPL"); 38 MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>"); 39 MODULE_ALIAS_NET_PF_PROTO(PF_NETLINK, NETLINK_NETFILTER); 40 41 static char __initdata nfversion[] = "0.30"; 42 43 static const struct nfnetlink_subsystem *subsys_table[NFNL_SUBSYS_COUNT]; 44 static DEFINE_MUTEX(nfnl_mutex); 45 46 void nfnl_lock(void) 47 { 48 mutex_lock(&nfnl_mutex); 49 } 50 EXPORT_SYMBOL_GPL(nfnl_lock); 51 52 void nfnl_unlock(void) 53 { 54 mutex_unlock(&nfnl_mutex); 55 } 56 EXPORT_SYMBOL_GPL(nfnl_unlock); 57 58 int nfnetlink_subsys_register(const struct nfnetlink_subsystem *n) 59 { 60 nfnl_lock(); 61 if (subsys_table[n->subsys_id]) { 62 nfnl_unlock(); 63 return -EBUSY; 64 } 65 subsys_table[n->subsys_id] = n; 66 nfnl_unlock(); 67 68 return 0; 69 } 70 EXPORT_SYMBOL_GPL(nfnetlink_subsys_register); 71 72 int nfnetlink_subsys_unregister(const struct nfnetlink_subsystem *n) 73 { 74 nfnl_lock(); 75 subsys_table[n->subsys_id] = NULL; 76 nfnl_unlock(); 77 78 return 0; 79 } 80 EXPORT_SYMBOL_GPL(nfnetlink_subsys_unregister); 81 82 static inline const struct nfnetlink_subsystem *nfnetlink_get_subsys(u_int16_t type) 83 { 84 u_int8_t subsys_id = NFNL_SUBSYS_ID(type); 85 86 if (subsys_id >= NFNL_SUBSYS_COUNT) 87 return NULL; 88 89 return subsys_table[subsys_id]; 90 } 91 92 static inline const struct nfnl_callback * 93 nfnetlink_find_client(u_int16_t type, const struct nfnetlink_subsystem *ss) 94 { 95 u_int8_t cb_id = NFNL_MSG_TYPE(type); 96 97 if (cb_id >= ss->cb_count) 98 return NULL; 99 100 return &ss->cb[cb_id]; 101 } 102 103 int nfnetlink_has_listeners(struct net *net, unsigned int group) 104 { 105 return netlink_has_listeners(net->nfnl, group); 106 } 107 EXPORT_SYMBOL_GPL(nfnetlink_has_listeners); 108 109 int nfnetlink_send(struct sk_buff *skb, struct net *net, u32 pid, 110 unsigned group, int echo, gfp_t flags) 111 { 112 return nlmsg_notify(net->nfnl, skb, pid, group, echo, flags); 113 } 114 EXPORT_SYMBOL_GPL(nfnetlink_send); 115 116 int nfnetlink_set_err(struct net *net, u32 pid, u32 group, int error) 117 { 118 return netlink_set_err(net->nfnl, pid, group, error); 119 } 120 EXPORT_SYMBOL_GPL(nfnetlink_set_err); 121 122 int nfnetlink_unicast(struct sk_buff *skb, struct net *net, u_int32_t pid, int flags) 123 { 124 return netlink_unicast(net->nfnl, skb, pid, flags); 125 } 126 EXPORT_SYMBOL_GPL(nfnetlink_unicast); 127 128 /* Process one complete nfnetlink message. */ 129 static int nfnetlink_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh) 130 { 131 struct net *net = sock_net(skb->sk); 132 const struct nfnl_callback *nc; 133 const struct nfnetlink_subsystem *ss; 134 int type, err; 135 136 if (security_netlink_recv(skb, CAP_NET_ADMIN)) 137 return -EPERM; 138 139 /* All the messages must at least contain nfgenmsg */ 140 if (nlh->nlmsg_len < NLMSG_LENGTH(sizeof(struct nfgenmsg))) 141 return 0; 142 143 type = nlh->nlmsg_type; 144 replay: 145 ss = nfnetlink_get_subsys(type); 146 if (!ss) { 147 #ifdef CONFIG_MODULES 148 nfnl_unlock(); 149 request_module("nfnetlink-subsys-%d", NFNL_SUBSYS_ID(type)); 150 nfnl_lock(); 151 ss = nfnetlink_get_subsys(type); 152 if (!ss) 153 #endif 154 return -EINVAL; 155 } 156 157 nc = nfnetlink_find_client(type, ss); 158 if (!nc) 159 return -EINVAL; 160 161 { 162 int min_len = NLMSG_SPACE(sizeof(struct nfgenmsg)); 163 u_int8_t cb_id = NFNL_MSG_TYPE(nlh->nlmsg_type); 164 struct nlattr *cda[ss->cb[cb_id].attr_count + 1]; 165 struct nlattr *attr = (void *)nlh + min_len; 166 int attrlen = nlh->nlmsg_len - min_len; 167 168 err = nla_parse(cda, ss->cb[cb_id].attr_count, 169 attr, attrlen, ss->cb[cb_id].policy); 170 if (err < 0) 171 return err; 172 173 err = nc->call(net->nfnl, skb, nlh, (const struct nlattr **)cda); 174 if (err == -EAGAIN) 175 goto replay; 176 return err; 177 } 178 } 179 180 static void nfnetlink_rcv(struct sk_buff *skb) 181 { 182 nfnl_lock(); 183 netlink_rcv_skb(skb, &nfnetlink_rcv_msg); 184 nfnl_unlock(); 185 } 186 187 static int __net_init nfnetlink_net_init(struct net *net) 188 { 189 struct sock *nfnl; 190 191 nfnl = netlink_kernel_create(net, NETLINK_NETFILTER, NFNLGRP_MAX, 192 nfnetlink_rcv, NULL, THIS_MODULE); 193 if (!nfnl) 194 return -ENOMEM; 195 net->nfnl_stash = nfnl; 196 rcu_assign_pointer(net->nfnl, nfnl); 197 return 0; 198 } 199 200 static void __net_exit nfnetlink_net_exit_batch(struct list_head *net_exit_list) 201 { 202 struct net *net; 203 204 list_for_each_entry(net, net_exit_list, exit_list) 205 rcu_assign_pointer(net->nfnl, NULL); 206 synchronize_net(); 207 list_for_each_entry(net, net_exit_list, exit_list) 208 netlink_kernel_release(net->nfnl_stash); 209 } 210 211 static struct pernet_operations nfnetlink_net_ops = { 212 .init = nfnetlink_net_init, 213 .exit_batch = nfnetlink_net_exit_batch, 214 }; 215 216 static int __init nfnetlink_init(void) 217 { 218 printk("Netfilter messages via NETLINK v%s.\n", nfversion); 219 return register_pernet_subsys(&nfnetlink_net_ops); 220 } 221 222 static void __exit nfnetlink_exit(void) 223 { 224 printk("Removing netfilter NETLINK layer.\n"); 225 unregister_pernet_subsys(&nfnetlink_net_ops); 226 } 227 module_init(nfnetlink_init); 228 module_exit(nfnetlink_exit); 229