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 <net/sock.h> 27 #include <net/netlink.h> 28 #include <linux/init.h> 29 30 #include <linux/netlink.h> 31 #include <linux/netfilter/nfnetlink.h> 32 33 MODULE_LICENSE("GPL"); 34 MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>"); 35 MODULE_ALIAS_NET_PF_PROTO(PF_NETLINK, NETLINK_NETFILTER); 36 37 static char __initdata nfversion[] = "0.30"; 38 39 static const struct nfnetlink_subsystem __rcu *subsys_table[NFNL_SUBSYS_COUNT]; 40 static DEFINE_MUTEX(nfnl_mutex); 41 42 void nfnl_lock(void) 43 { 44 mutex_lock(&nfnl_mutex); 45 } 46 EXPORT_SYMBOL_GPL(nfnl_lock); 47 48 void nfnl_unlock(void) 49 { 50 mutex_unlock(&nfnl_mutex); 51 } 52 EXPORT_SYMBOL_GPL(nfnl_unlock); 53 54 int nfnetlink_subsys_register(const struct nfnetlink_subsystem *n) 55 { 56 nfnl_lock(); 57 if (subsys_table[n->subsys_id]) { 58 nfnl_unlock(); 59 return -EBUSY; 60 } 61 rcu_assign_pointer(subsys_table[n->subsys_id], n); 62 nfnl_unlock(); 63 64 return 0; 65 } 66 EXPORT_SYMBOL_GPL(nfnetlink_subsys_register); 67 68 int nfnetlink_subsys_unregister(const struct nfnetlink_subsystem *n) 69 { 70 nfnl_lock(); 71 subsys_table[n->subsys_id] = NULL; 72 nfnl_unlock(); 73 synchronize_rcu(); 74 return 0; 75 } 76 EXPORT_SYMBOL_GPL(nfnetlink_subsys_unregister); 77 78 static inline const struct nfnetlink_subsystem *nfnetlink_get_subsys(u_int16_t type) 79 { 80 u_int8_t subsys_id = NFNL_SUBSYS_ID(type); 81 82 if (subsys_id >= NFNL_SUBSYS_COUNT) 83 return NULL; 84 85 return rcu_dereference(subsys_table[subsys_id]); 86 } 87 88 static inline const struct nfnl_callback * 89 nfnetlink_find_client(u_int16_t type, const struct nfnetlink_subsystem *ss) 90 { 91 u_int8_t cb_id = NFNL_MSG_TYPE(type); 92 93 if (cb_id >= ss->cb_count) 94 return NULL; 95 96 return &ss->cb[cb_id]; 97 } 98 99 int nfnetlink_has_listeners(struct net *net, unsigned int group) 100 { 101 return netlink_has_listeners(net->nfnl, group); 102 } 103 EXPORT_SYMBOL_GPL(nfnetlink_has_listeners); 104 105 int nfnetlink_send(struct sk_buff *skb, struct net *net, u32 pid, 106 unsigned group, int echo, gfp_t flags) 107 { 108 return nlmsg_notify(net->nfnl, skb, pid, group, echo, flags); 109 } 110 EXPORT_SYMBOL_GPL(nfnetlink_send); 111 112 int nfnetlink_set_err(struct net *net, u32 pid, u32 group, int error) 113 { 114 return netlink_set_err(net->nfnl, pid, group, error); 115 } 116 EXPORT_SYMBOL_GPL(nfnetlink_set_err); 117 118 int nfnetlink_unicast(struct sk_buff *skb, struct net *net, u_int32_t pid, int flags) 119 { 120 return netlink_unicast(net->nfnl, skb, pid, flags); 121 } 122 EXPORT_SYMBOL_GPL(nfnetlink_unicast); 123 124 /* Process one complete nfnetlink message. */ 125 static int nfnetlink_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh) 126 { 127 struct net *net = sock_net(skb->sk); 128 const struct nfnl_callback *nc; 129 const struct nfnetlink_subsystem *ss; 130 int type, err; 131 132 if (!capable(CAP_NET_ADMIN)) 133 return -EPERM; 134 135 /* All the messages must at least contain nfgenmsg */ 136 if (nlh->nlmsg_len < NLMSG_LENGTH(sizeof(struct nfgenmsg))) 137 return 0; 138 139 type = nlh->nlmsg_type; 140 replay: 141 rcu_read_lock(); 142 ss = nfnetlink_get_subsys(type); 143 if (!ss) { 144 #ifdef CONFIG_MODULES 145 rcu_read_unlock(); 146 request_module("nfnetlink-subsys-%d", NFNL_SUBSYS_ID(type)); 147 rcu_read_lock(); 148 ss = nfnetlink_get_subsys(type); 149 if (!ss) 150 #endif 151 { 152 rcu_read_unlock(); 153 return -EINVAL; 154 } 155 } 156 157 nc = nfnetlink_find_client(type, ss); 158 if (!nc) { 159 rcu_read_unlock(); 160 return -EINVAL; 161 } 162 163 { 164 int min_len = NLMSG_SPACE(sizeof(struct nfgenmsg)); 165 u_int8_t cb_id = NFNL_MSG_TYPE(nlh->nlmsg_type); 166 struct nlattr *cda[ss->cb[cb_id].attr_count + 1]; 167 struct nlattr *attr = (void *)nlh + min_len; 168 int attrlen = nlh->nlmsg_len - min_len; 169 170 err = nla_parse(cda, ss->cb[cb_id].attr_count, 171 attr, attrlen, ss->cb[cb_id].policy); 172 if (err < 0) 173 return err; 174 175 if (nc->call_rcu) { 176 err = nc->call_rcu(net->nfnl, skb, nlh, 177 (const struct nlattr **)cda); 178 rcu_read_unlock(); 179 } else { 180 rcu_read_unlock(); 181 nfnl_lock(); 182 if (rcu_dereference_protected( 183 subsys_table[NFNL_SUBSYS_ID(type)], 184 lockdep_is_held(&nfnl_mutex)) != ss || 185 nfnetlink_find_client(type, ss) != nc) 186 err = -EAGAIN; 187 else 188 err = nc->call(net->nfnl, skb, nlh, 189 (const struct nlattr **)cda); 190 nfnl_unlock(); 191 } 192 if (err == -EAGAIN) 193 goto replay; 194 return err; 195 } 196 } 197 198 static void nfnetlink_rcv(struct sk_buff *skb) 199 { 200 netlink_rcv_skb(skb, &nfnetlink_rcv_msg); 201 } 202 203 static int __net_init nfnetlink_net_init(struct net *net) 204 { 205 struct sock *nfnl; 206 207 nfnl = netlink_kernel_create(net, NETLINK_NETFILTER, NFNLGRP_MAX, 208 nfnetlink_rcv, NULL, THIS_MODULE); 209 if (!nfnl) 210 return -ENOMEM; 211 net->nfnl_stash = nfnl; 212 rcu_assign_pointer(net->nfnl, nfnl); 213 return 0; 214 } 215 216 static void __net_exit nfnetlink_net_exit_batch(struct list_head *net_exit_list) 217 { 218 struct net *net; 219 220 list_for_each_entry(net, net_exit_list, exit_list) 221 RCU_INIT_POINTER(net->nfnl, NULL); 222 synchronize_net(); 223 list_for_each_entry(net, net_exit_list, exit_list) 224 netlink_kernel_release(net->nfnl_stash); 225 } 226 227 static struct pernet_operations nfnetlink_net_ops = { 228 .init = nfnetlink_net_init, 229 .exit_batch = nfnetlink_net_exit_batch, 230 }; 231 232 static int __init nfnetlink_init(void) 233 { 234 pr_info("Netfilter messages via NETLINK v%s.\n", nfversion); 235 return register_pernet_subsys(&nfnetlink_net_ops); 236 } 237 238 static void __exit nfnetlink_exit(void) 239 { 240 pr_info("Removing netfilter NETLINK layer.\n"); 241 unregister_pernet_subsys(&nfnetlink_net_ops); 242 } 243 module_init(nfnetlink_init); 244 module_exit(nfnetlink_exit); 245