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 static const int nfnl_group2type[NFNLGRP_MAX+1] = { 43 [NFNLGRP_CONNTRACK_NEW] = NFNL_SUBSYS_CTNETLINK, 44 [NFNLGRP_CONNTRACK_UPDATE] = NFNL_SUBSYS_CTNETLINK, 45 [NFNLGRP_CONNTRACK_DESTROY] = NFNL_SUBSYS_CTNETLINK, 46 [NFNLGRP_CONNTRACK_EXP_NEW] = NFNL_SUBSYS_CTNETLINK_EXP, 47 [NFNLGRP_CONNTRACK_EXP_UPDATE] = NFNL_SUBSYS_CTNETLINK_EXP, 48 [NFNLGRP_CONNTRACK_EXP_DESTROY] = NFNL_SUBSYS_CTNETLINK_EXP, 49 }; 50 51 void nfnl_lock(void) 52 { 53 mutex_lock(&nfnl_mutex); 54 } 55 EXPORT_SYMBOL_GPL(nfnl_lock); 56 57 void nfnl_unlock(void) 58 { 59 mutex_unlock(&nfnl_mutex); 60 } 61 EXPORT_SYMBOL_GPL(nfnl_unlock); 62 63 int nfnetlink_subsys_register(const struct nfnetlink_subsystem *n) 64 { 65 nfnl_lock(); 66 if (subsys_table[n->subsys_id]) { 67 nfnl_unlock(); 68 return -EBUSY; 69 } 70 rcu_assign_pointer(subsys_table[n->subsys_id], n); 71 nfnl_unlock(); 72 73 return 0; 74 } 75 EXPORT_SYMBOL_GPL(nfnetlink_subsys_register); 76 77 int nfnetlink_subsys_unregister(const struct nfnetlink_subsystem *n) 78 { 79 nfnl_lock(); 80 subsys_table[n->subsys_id] = NULL; 81 nfnl_unlock(); 82 synchronize_rcu(); 83 return 0; 84 } 85 EXPORT_SYMBOL_GPL(nfnetlink_subsys_unregister); 86 87 static inline const struct nfnetlink_subsystem *nfnetlink_get_subsys(u_int16_t type) 88 { 89 u_int8_t subsys_id = NFNL_SUBSYS_ID(type); 90 91 if (subsys_id >= NFNL_SUBSYS_COUNT) 92 return NULL; 93 94 return rcu_dereference(subsys_table[subsys_id]); 95 } 96 97 static inline const struct nfnl_callback * 98 nfnetlink_find_client(u_int16_t type, const struct nfnetlink_subsystem *ss) 99 { 100 u_int8_t cb_id = NFNL_MSG_TYPE(type); 101 102 if (cb_id >= ss->cb_count) 103 return NULL; 104 105 return &ss->cb[cb_id]; 106 } 107 108 int nfnetlink_has_listeners(struct net *net, unsigned int group) 109 { 110 return netlink_has_listeners(net->nfnl, group); 111 } 112 EXPORT_SYMBOL_GPL(nfnetlink_has_listeners); 113 114 int nfnetlink_send(struct sk_buff *skb, struct net *net, u32 pid, 115 unsigned int group, int echo, gfp_t flags) 116 { 117 return nlmsg_notify(net->nfnl, skb, pid, group, echo, flags); 118 } 119 EXPORT_SYMBOL_GPL(nfnetlink_send); 120 121 int nfnetlink_set_err(struct net *net, u32 pid, u32 group, int error) 122 { 123 return netlink_set_err(net->nfnl, pid, group, error); 124 } 125 EXPORT_SYMBOL_GPL(nfnetlink_set_err); 126 127 int nfnetlink_unicast(struct sk_buff *skb, struct net *net, u_int32_t pid, int flags) 128 { 129 return netlink_unicast(net->nfnl, skb, pid, flags); 130 } 131 EXPORT_SYMBOL_GPL(nfnetlink_unicast); 132 133 /* Process one complete nfnetlink message. */ 134 static int nfnetlink_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh) 135 { 136 struct net *net = sock_net(skb->sk); 137 const struct nfnl_callback *nc; 138 const struct nfnetlink_subsystem *ss; 139 int type, err; 140 141 if (!ns_capable(net->user_ns, CAP_NET_ADMIN)) 142 return -EPERM; 143 144 /* All the messages must at least contain nfgenmsg */ 145 if (nlh->nlmsg_len < NLMSG_LENGTH(sizeof(struct nfgenmsg))) 146 return 0; 147 148 type = nlh->nlmsg_type; 149 replay: 150 rcu_read_lock(); 151 ss = nfnetlink_get_subsys(type); 152 if (!ss) { 153 #ifdef CONFIG_MODULES 154 rcu_read_unlock(); 155 request_module("nfnetlink-subsys-%d", NFNL_SUBSYS_ID(type)); 156 rcu_read_lock(); 157 ss = nfnetlink_get_subsys(type); 158 if (!ss) 159 #endif 160 { 161 rcu_read_unlock(); 162 return -EINVAL; 163 } 164 } 165 166 nc = nfnetlink_find_client(type, ss); 167 if (!nc) { 168 rcu_read_unlock(); 169 return -EINVAL; 170 } 171 172 { 173 int min_len = NLMSG_SPACE(sizeof(struct nfgenmsg)); 174 u_int8_t cb_id = NFNL_MSG_TYPE(nlh->nlmsg_type); 175 struct nlattr *cda[ss->cb[cb_id].attr_count + 1]; 176 struct nlattr *attr = (void *)nlh + min_len; 177 int attrlen = nlh->nlmsg_len - min_len; 178 179 err = nla_parse(cda, ss->cb[cb_id].attr_count, 180 attr, attrlen, ss->cb[cb_id].policy); 181 if (err < 0) { 182 rcu_read_unlock(); 183 return err; 184 } 185 186 if (nc->call_rcu) { 187 err = nc->call_rcu(net->nfnl, skb, nlh, 188 (const struct nlattr **)cda); 189 rcu_read_unlock(); 190 } else { 191 rcu_read_unlock(); 192 nfnl_lock(); 193 if (rcu_dereference_protected( 194 subsys_table[NFNL_SUBSYS_ID(type)], 195 lockdep_is_held(&nfnl_mutex)) != ss || 196 nfnetlink_find_client(type, ss) != nc) 197 err = -EAGAIN; 198 else if (nc->call) 199 err = nc->call(net->nfnl, skb, nlh, 200 (const struct nlattr **)cda); 201 else 202 err = -EINVAL; 203 nfnl_unlock(); 204 } 205 if (err == -EAGAIN) 206 goto replay; 207 return err; 208 } 209 } 210 211 static void nfnetlink_rcv(struct sk_buff *skb) 212 { 213 netlink_rcv_skb(skb, &nfnetlink_rcv_msg); 214 } 215 216 #ifdef CONFIG_MODULES 217 static void nfnetlink_bind(int group) 218 { 219 const struct nfnetlink_subsystem *ss; 220 int type = nfnl_group2type[group]; 221 222 rcu_read_lock(); 223 ss = nfnetlink_get_subsys(type); 224 if (!ss) { 225 rcu_read_unlock(); 226 request_module("nfnetlink-subsys-%d", type); 227 return; 228 } 229 rcu_read_unlock(); 230 } 231 #endif 232 233 static int __net_init nfnetlink_net_init(struct net *net) 234 { 235 struct sock *nfnl; 236 struct netlink_kernel_cfg cfg = { 237 .groups = NFNLGRP_MAX, 238 .input = nfnetlink_rcv, 239 #ifdef CONFIG_MODULES 240 .bind = nfnetlink_bind, 241 #endif 242 }; 243 244 nfnl = netlink_kernel_create(net, NETLINK_NETFILTER, &cfg); 245 if (!nfnl) 246 return -ENOMEM; 247 net->nfnl_stash = nfnl; 248 rcu_assign_pointer(net->nfnl, nfnl); 249 return 0; 250 } 251 252 static void __net_exit nfnetlink_net_exit_batch(struct list_head *net_exit_list) 253 { 254 struct net *net; 255 256 list_for_each_entry(net, net_exit_list, exit_list) 257 RCU_INIT_POINTER(net->nfnl, NULL); 258 synchronize_net(); 259 list_for_each_entry(net, net_exit_list, exit_list) 260 netlink_kernel_release(net->nfnl_stash); 261 } 262 263 static struct pernet_operations nfnetlink_net_ops = { 264 .init = nfnetlink_net_init, 265 .exit_batch = nfnetlink_net_exit_batch, 266 }; 267 268 static int __init nfnetlink_init(void) 269 { 270 pr_info("Netfilter messages via NETLINK v%s.\n", nfversion); 271 return register_pernet_subsys(&nfnetlink_net_ops); 272 } 273 274 static void __exit nfnetlink_exit(void) 275 { 276 pr_info("Removing netfilter NETLINK layer.\n"); 277 unregister_pernet_subsys(&nfnetlink_net_ops); 278 } 279 module_init(nfnetlink_init); 280 module_exit(nfnetlink_exit); 281