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