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 34 MODULE_LICENSE("GPL"); 35 MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>"); 36 MODULE_ALIAS_NET_PF_PROTO(PF_NETLINK, NETLINK_NETFILTER); 37 38 static char __initdata nfversion[] = "0.30"; 39 40 static const struct nfnetlink_subsystem __rcu *subsys_table[NFNL_SUBSYS_COUNT]; 41 static DEFINE_MUTEX(nfnl_mutex); 42 43 void nfnl_lock(void) 44 { 45 mutex_lock(&nfnl_mutex); 46 } 47 EXPORT_SYMBOL_GPL(nfnl_lock); 48 49 void nfnl_unlock(void) 50 { 51 mutex_unlock(&nfnl_mutex); 52 } 53 EXPORT_SYMBOL_GPL(nfnl_unlock); 54 55 int 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 rcu_assign_pointer(subsys_table[n->subsys_id], n); 63 nfnl_unlock(); 64 65 return 0; 66 } 67 EXPORT_SYMBOL_GPL(nfnetlink_subsys_register); 68 69 int nfnetlink_subsys_unregister(const struct nfnetlink_subsystem *n) 70 { 71 nfnl_lock(); 72 subsys_table[n->subsys_id] = NULL; 73 nfnl_unlock(); 74 synchronize_rcu(); 75 return 0; 76 } 77 EXPORT_SYMBOL_GPL(nfnetlink_subsys_unregister); 78 79 static 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 rcu_dereference(subsys_table[subsys_id]); 87 } 88 89 static inline const struct nfnl_callback * 90 nfnetlink_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 } 99 100 int nfnetlink_has_listeners(struct net *net, unsigned int group) 101 { 102 return netlink_has_listeners(net->nfnl, group); 103 } 104 EXPORT_SYMBOL_GPL(nfnetlink_has_listeners); 105 106 int 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 } 111 EXPORT_SYMBOL_GPL(nfnetlink_send); 112 113 int nfnetlink_set_err(struct net *net, u32 pid, u32 group, int error) 114 { 115 return netlink_set_err(net->nfnl, pid, group, error); 116 } 117 EXPORT_SYMBOL_GPL(nfnetlink_set_err); 118 119 int 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 } 123 EXPORT_SYMBOL_GPL(nfnetlink_unicast); 124 125 /* Process one complete nfnetlink message. */ 126 static 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 (!capable(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; 141 replay: 142 rcu_read_lock(); 143 ss = nfnetlink_get_subsys(type); 144 if (!ss) { 145 #ifdef CONFIG_MODULES 146 rcu_read_unlock(); 147 request_module("nfnetlink-subsys-%d", NFNL_SUBSYS_ID(type)); 148 rcu_read_lock(); 149 ss = nfnetlink_get_subsys(type); 150 if (!ss) 151 #endif 152 { 153 rcu_read_unlock(); 154 return -EINVAL; 155 } 156 } 157 158 nc = nfnetlink_find_client(type, ss); 159 if (!nc) { 160 rcu_read_unlock(); 161 return -EINVAL; 162 } 163 164 { 165 int min_len = NLMSG_SPACE(sizeof(struct nfgenmsg)); 166 u_int8_t cb_id = NFNL_MSG_TYPE(nlh->nlmsg_type); 167 struct nlattr *cda[ss->cb[cb_id].attr_count + 1]; 168 struct nlattr *attr = (void *)nlh + min_len; 169 int attrlen = nlh->nlmsg_len - min_len; 170 171 err = nla_parse(cda, ss->cb[cb_id].attr_count, 172 attr, attrlen, ss->cb[cb_id].policy); 173 if (err < 0) 174 return err; 175 176 if (nc->call_rcu) { 177 err = nc->call_rcu(net->nfnl, skb, nlh, 178 (const struct nlattr **)cda); 179 rcu_read_unlock(); 180 } else { 181 rcu_read_unlock(); 182 nfnl_lock(); 183 if (rcu_dereference_protected( 184 subsys_table[NFNL_SUBSYS_ID(type)], 185 lockdep_is_held(&nfnl_mutex)) != ss || 186 nfnetlink_find_client(type, ss) != nc) 187 err = -EAGAIN; 188 else 189 err = nc->call(net->nfnl, skb, nlh, 190 (const struct nlattr **)cda); 191 nfnl_unlock(); 192 } 193 if (err == -EAGAIN) 194 goto replay; 195 return err; 196 } 197 } 198 199 static void nfnetlink_rcv(struct sk_buff *skb) 200 { 201 netlink_rcv_skb(skb, &nfnetlink_rcv_msg); 202 } 203 204 static int __net_init nfnetlink_net_init(struct net *net) 205 { 206 struct sock *nfnl; 207 208 nfnl = netlink_kernel_create(net, NETLINK_NETFILTER, NFNLGRP_MAX, 209 nfnetlink_rcv, NULL, THIS_MODULE); 210 if (!nfnl) 211 return -ENOMEM; 212 net->nfnl_stash = nfnl; 213 rcu_assign_pointer(net->nfnl, nfnl); 214 return 0; 215 } 216 217 static void __net_exit nfnetlink_net_exit_batch(struct list_head *net_exit_list) 218 { 219 struct net *net; 220 221 list_for_each_entry(net, net_exit_list, exit_list) 222 RCU_INIT_POINTER(net->nfnl, NULL); 223 synchronize_net(); 224 list_for_each_entry(net, net_exit_list, exit_list) 225 netlink_kernel_release(net->nfnl_stash); 226 } 227 228 static struct pernet_operations nfnetlink_net_ops = { 229 .init = nfnetlink_net_init, 230 .exit_batch = nfnetlink_net_exit_batch, 231 }; 232 233 static int __init nfnetlink_init(void) 234 { 235 pr_info("Netfilter messages via NETLINK v%s.\n", nfversion); 236 return register_pernet_subsys(&nfnetlink_net_ops); 237 } 238 239 static void __exit nfnetlink_exit(void) 240 { 241 pr_info("Removing netfilter NETLINK layer.\n"); 242 unregister_pernet_subsys(&nfnetlink_net_ops); 243 } 244 module_init(nfnetlink_init); 245 module_exit(nfnetlink_exit); 246