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 <linux/init.h> 28 29 #include <net/netlink.h> 30 #include <linux/netfilter/nfnetlink.h> 31 32 MODULE_LICENSE("GPL"); 33 MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>"); 34 MODULE_ALIAS_NET_PF_PROTO(PF_NETLINK, NETLINK_NETFILTER); 35 36 static char __initdata nfversion[] = "0.30"; 37 38 static struct { 39 struct mutex mutex; 40 const struct nfnetlink_subsystem __rcu *subsys; 41 } table[NFNL_SUBSYS_COUNT]; 42 43 static const int nfnl_group2type[NFNLGRP_MAX+1] = { 44 [NFNLGRP_CONNTRACK_NEW] = NFNL_SUBSYS_CTNETLINK, 45 [NFNLGRP_CONNTRACK_UPDATE] = NFNL_SUBSYS_CTNETLINK, 46 [NFNLGRP_CONNTRACK_DESTROY] = NFNL_SUBSYS_CTNETLINK, 47 [NFNLGRP_CONNTRACK_EXP_NEW] = NFNL_SUBSYS_CTNETLINK_EXP, 48 [NFNLGRP_CONNTRACK_EXP_UPDATE] = NFNL_SUBSYS_CTNETLINK_EXP, 49 [NFNLGRP_CONNTRACK_EXP_DESTROY] = NFNL_SUBSYS_CTNETLINK_EXP, 50 }; 51 52 void nfnl_lock(__u8 subsys_id) 53 { 54 mutex_lock(&table[subsys_id].mutex); 55 } 56 EXPORT_SYMBOL_GPL(nfnl_lock); 57 58 void nfnl_unlock(__u8 subsys_id) 59 { 60 mutex_unlock(&table[subsys_id].mutex); 61 } 62 EXPORT_SYMBOL_GPL(nfnl_unlock); 63 64 int nfnetlink_subsys_register(const struct nfnetlink_subsystem *n) 65 { 66 nfnl_lock(n->subsys_id); 67 if (table[n->subsys_id].subsys) { 68 nfnl_unlock(n->subsys_id); 69 return -EBUSY; 70 } 71 rcu_assign_pointer(table[n->subsys_id].subsys, n); 72 nfnl_unlock(n->subsys_id); 73 74 return 0; 75 } 76 EXPORT_SYMBOL_GPL(nfnetlink_subsys_register); 77 78 int nfnetlink_subsys_unregister(const struct nfnetlink_subsystem *n) 79 { 80 nfnl_lock(n->subsys_id); 81 table[n->subsys_id].subsys = NULL; 82 nfnl_unlock(n->subsys_id); 83 synchronize_rcu(); 84 return 0; 85 } 86 EXPORT_SYMBOL_GPL(nfnetlink_subsys_unregister); 87 88 static inline const struct nfnetlink_subsystem *nfnetlink_get_subsys(u_int16_t type) 89 { 90 u_int8_t subsys_id = NFNL_SUBSYS_ID(type); 91 92 if (subsys_id >= NFNL_SUBSYS_COUNT) 93 return NULL; 94 95 return rcu_dereference(table[subsys_id].subsys); 96 } 97 98 static inline const struct nfnl_callback * 99 nfnetlink_find_client(u_int16_t type, const struct nfnetlink_subsystem *ss) 100 { 101 u_int8_t cb_id = NFNL_MSG_TYPE(type); 102 103 if (cb_id >= ss->cb_count) 104 return NULL; 105 106 return &ss->cb[cb_id]; 107 } 108 109 int nfnetlink_has_listeners(struct net *net, unsigned int group) 110 { 111 return netlink_has_listeners(net->nfnl, group); 112 } 113 EXPORT_SYMBOL_GPL(nfnetlink_has_listeners); 114 115 struct sk_buff *nfnetlink_alloc_skb(struct net *net, unsigned int size, 116 u32 dst_portid, gfp_t gfp_mask) 117 { 118 return netlink_alloc_skb(net->nfnl, size, dst_portid, gfp_mask); 119 } 120 EXPORT_SYMBOL_GPL(nfnetlink_alloc_skb); 121 122 int nfnetlink_send(struct sk_buff *skb, struct net *net, u32 portid, 123 unsigned int group, int echo, gfp_t flags) 124 { 125 return nlmsg_notify(net->nfnl, skb, portid, group, echo, flags); 126 } 127 EXPORT_SYMBOL_GPL(nfnetlink_send); 128 129 int nfnetlink_set_err(struct net *net, u32 portid, u32 group, int error) 130 { 131 return netlink_set_err(net->nfnl, portid, group, error); 132 } 133 EXPORT_SYMBOL_GPL(nfnetlink_set_err); 134 135 int nfnetlink_unicast(struct sk_buff *skb, struct net *net, u32 portid, 136 int flags) 137 { 138 return netlink_unicast(net->nfnl, skb, portid, flags); 139 } 140 EXPORT_SYMBOL_GPL(nfnetlink_unicast); 141 142 /* Process one complete nfnetlink message. */ 143 static int nfnetlink_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh) 144 { 145 struct net *net = sock_net(skb->sk); 146 const struct nfnl_callback *nc; 147 const struct nfnetlink_subsystem *ss; 148 int type, err; 149 150 if (!ns_capable(net->user_ns, CAP_NET_ADMIN)) 151 return -EPERM; 152 153 /* All the messages must at least contain nfgenmsg */ 154 if (nlmsg_len(nlh) < sizeof(struct nfgenmsg)) 155 return 0; 156 157 type = nlh->nlmsg_type; 158 replay: 159 rcu_read_lock(); 160 ss = nfnetlink_get_subsys(type); 161 if (!ss) { 162 #ifdef CONFIG_MODULES 163 rcu_read_unlock(); 164 request_module("nfnetlink-subsys-%d", NFNL_SUBSYS_ID(type)); 165 rcu_read_lock(); 166 ss = nfnetlink_get_subsys(type); 167 if (!ss) 168 #endif 169 { 170 rcu_read_unlock(); 171 return -EINVAL; 172 } 173 } 174 175 nc = nfnetlink_find_client(type, ss); 176 if (!nc) { 177 rcu_read_unlock(); 178 return -EINVAL; 179 } 180 181 { 182 int min_len = nlmsg_total_size(sizeof(struct nfgenmsg)); 183 u_int8_t cb_id = NFNL_MSG_TYPE(nlh->nlmsg_type); 184 struct nlattr *cda[ss->cb[cb_id].attr_count + 1]; 185 struct nlattr *attr = (void *)nlh + min_len; 186 int attrlen = nlh->nlmsg_len - min_len; 187 __u8 subsys_id = NFNL_SUBSYS_ID(type); 188 189 err = nla_parse(cda, ss->cb[cb_id].attr_count, 190 attr, attrlen, ss->cb[cb_id].policy); 191 if (err < 0) { 192 rcu_read_unlock(); 193 return err; 194 } 195 196 if (nc->call_rcu) { 197 err = nc->call_rcu(net->nfnl, skb, nlh, 198 (const struct nlattr **)cda); 199 rcu_read_unlock(); 200 } else { 201 rcu_read_unlock(); 202 nfnl_lock(subsys_id); 203 if (rcu_dereference_protected(table[subsys_id].subsys, 204 lockdep_is_held(&table[subsys_id].mutex)) != ss || 205 nfnetlink_find_client(type, ss) != nc) 206 err = -EAGAIN; 207 else if (nc->call) 208 err = nc->call(net->nfnl, skb, nlh, 209 (const struct nlattr **)cda); 210 else 211 err = -EINVAL; 212 nfnl_unlock(subsys_id); 213 } 214 if (err == -EAGAIN) 215 goto replay; 216 return err; 217 } 218 } 219 220 static void nfnetlink_rcv(struct sk_buff *skb) 221 { 222 netlink_rcv_skb(skb, &nfnetlink_rcv_msg); 223 } 224 225 #ifdef CONFIG_MODULES 226 static void nfnetlink_bind(int group) 227 { 228 const struct nfnetlink_subsystem *ss; 229 int type = nfnl_group2type[group]; 230 231 rcu_read_lock(); 232 ss = nfnetlink_get_subsys(type); 233 if (!ss) { 234 rcu_read_unlock(); 235 request_module("nfnetlink-subsys-%d", type); 236 return; 237 } 238 rcu_read_unlock(); 239 } 240 #endif 241 242 static int __net_init nfnetlink_net_init(struct net *net) 243 { 244 struct sock *nfnl; 245 struct netlink_kernel_cfg cfg = { 246 .groups = NFNLGRP_MAX, 247 .input = nfnetlink_rcv, 248 #ifdef CONFIG_MODULES 249 .bind = nfnetlink_bind, 250 #endif 251 }; 252 253 nfnl = netlink_kernel_create(net, NETLINK_NETFILTER, &cfg); 254 if (!nfnl) 255 return -ENOMEM; 256 net->nfnl_stash = nfnl; 257 rcu_assign_pointer(net->nfnl, nfnl); 258 return 0; 259 } 260 261 static void __net_exit nfnetlink_net_exit_batch(struct list_head *net_exit_list) 262 { 263 struct net *net; 264 265 list_for_each_entry(net, net_exit_list, exit_list) 266 RCU_INIT_POINTER(net->nfnl, NULL); 267 synchronize_net(); 268 list_for_each_entry(net, net_exit_list, exit_list) 269 netlink_kernel_release(net->nfnl_stash); 270 } 271 272 static struct pernet_operations nfnetlink_net_ops = { 273 .init = nfnetlink_net_init, 274 .exit_batch = nfnetlink_net_exit_batch, 275 }; 276 277 static int __init nfnetlink_init(void) 278 { 279 int i; 280 281 for (i=0; i<NFNL_SUBSYS_COUNT; i++) 282 mutex_init(&table[i].mutex); 283 284 pr_info("Netfilter messages via NETLINK v%s.\n", nfversion); 285 return register_pernet_subsys(&nfnetlink_net_ops); 286 } 287 288 static void __exit nfnetlink_exit(void) 289 { 290 pr_info("Removing netfilter NETLINK layer.\n"); 291 unregister_pernet_subsys(&nfnetlink_net_ops); 292 } 293 module_init(nfnetlink_init); 294 module_exit(nfnetlink_exit); 295