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 struct { 40 struct mutex mutex; 41 const struct nfnetlink_subsystem __rcu *subsys; 42 } table[NFNL_SUBSYS_COUNT]; 43 44 static const int nfnl_group2type[NFNLGRP_MAX+1] = { 45 [NFNLGRP_CONNTRACK_NEW] = NFNL_SUBSYS_CTNETLINK, 46 [NFNLGRP_CONNTRACK_UPDATE] = NFNL_SUBSYS_CTNETLINK, 47 [NFNLGRP_CONNTRACK_DESTROY] = NFNL_SUBSYS_CTNETLINK, 48 [NFNLGRP_CONNTRACK_EXP_NEW] = NFNL_SUBSYS_CTNETLINK_EXP, 49 [NFNLGRP_CONNTRACK_EXP_UPDATE] = NFNL_SUBSYS_CTNETLINK_EXP, 50 [NFNLGRP_CONNTRACK_EXP_DESTROY] = NFNL_SUBSYS_CTNETLINK_EXP, 51 }; 52 53 void nfnl_lock(__u8 subsys_id) 54 { 55 mutex_lock(&table[subsys_id].mutex); 56 } 57 EXPORT_SYMBOL_GPL(nfnl_lock); 58 59 void nfnl_unlock(__u8 subsys_id) 60 { 61 mutex_unlock(&table[subsys_id].mutex); 62 } 63 EXPORT_SYMBOL_GPL(nfnl_unlock); 64 65 int nfnetlink_subsys_register(const struct nfnetlink_subsystem *n) 66 { 67 nfnl_lock(n->subsys_id); 68 if (table[n->subsys_id].subsys) { 69 nfnl_unlock(n->subsys_id); 70 return -EBUSY; 71 } 72 rcu_assign_pointer(table[n->subsys_id].subsys, n); 73 nfnl_unlock(n->subsys_id); 74 75 return 0; 76 } 77 EXPORT_SYMBOL_GPL(nfnetlink_subsys_register); 78 79 int nfnetlink_subsys_unregister(const struct nfnetlink_subsystem *n) 80 { 81 nfnl_lock(n->subsys_id); 82 table[n->subsys_id].subsys = NULL; 83 nfnl_unlock(n->subsys_id); 84 synchronize_rcu(); 85 return 0; 86 } 87 EXPORT_SYMBOL_GPL(nfnetlink_subsys_unregister); 88 89 static inline const struct nfnetlink_subsystem *nfnetlink_get_subsys(u_int16_t type) 90 { 91 u_int8_t subsys_id = NFNL_SUBSYS_ID(type); 92 93 if (subsys_id >= NFNL_SUBSYS_COUNT) 94 return NULL; 95 96 return rcu_dereference(table[subsys_id].subsys); 97 } 98 99 static inline const struct nfnl_callback * 100 nfnetlink_find_client(u_int16_t type, const struct nfnetlink_subsystem *ss) 101 { 102 u_int8_t cb_id = NFNL_MSG_TYPE(type); 103 104 if (cb_id >= ss->cb_count) 105 return NULL; 106 107 return &ss->cb[cb_id]; 108 } 109 110 int nfnetlink_has_listeners(struct net *net, unsigned int group) 111 { 112 return netlink_has_listeners(net->nfnl, group); 113 } 114 EXPORT_SYMBOL_GPL(nfnetlink_has_listeners); 115 116 int nfnetlink_send(struct sk_buff *skb, struct net *net, u32 pid, 117 unsigned int group, int echo, gfp_t flags) 118 { 119 return nlmsg_notify(net->nfnl, skb, pid, group, echo, flags); 120 } 121 EXPORT_SYMBOL_GPL(nfnetlink_send); 122 123 int nfnetlink_set_err(struct net *net, u32 pid, u32 group, int error) 124 { 125 return netlink_set_err(net->nfnl, pid, group, error); 126 } 127 EXPORT_SYMBOL_GPL(nfnetlink_set_err); 128 129 int nfnetlink_unicast(struct sk_buff *skb, struct net *net, u_int32_t pid, int flags) 130 { 131 return netlink_unicast(net->nfnl, skb, pid, flags); 132 } 133 EXPORT_SYMBOL_GPL(nfnetlink_unicast); 134 135 /* Process one complete nfnetlink message. */ 136 static int nfnetlink_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh) 137 { 138 struct net *net = sock_net(skb->sk); 139 const struct nfnl_callback *nc; 140 const struct nfnetlink_subsystem *ss; 141 int type, err; 142 143 if (!ns_capable(net->user_ns, CAP_NET_ADMIN)) 144 return -EPERM; 145 146 /* All the messages must at least contain nfgenmsg */ 147 if (nlh->nlmsg_len < NLMSG_LENGTH(sizeof(struct nfgenmsg))) 148 return 0; 149 150 type = nlh->nlmsg_type; 151 replay: 152 rcu_read_lock(); 153 ss = nfnetlink_get_subsys(type); 154 if (!ss) { 155 #ifdef CONFIG_MODULES 156 rcu_read_unlock(); 157 request_module("nfnetlink-subsys-%d", NFNL_SUBSYS_ID(type)); 158 rcu_read_lock(); 159 ss = nfnetlink_get_subsys(type); 160 if (!ss) 161 #endif 162 { 163 rcu_read_unlock(); 164 return -EINVAL; 165 } 166 } 167 168 nc = nfnetlink_find_client(type, ss); 169 if (!nc) { 170 rcu_read_unlock(); 171 return -EINVAL; 172 } 173 174 { 175 int min_len = NLMSG_SPACE(sizeof(struct nfgenmsg)); 176 u_int8_t cb_id = NFNL_MSG_TYPE(nlh->nlmsg_type); 177 struct nlattr *cda[ss->cb[cb_id].attr_count + 1]; 178 struct nlattr *attr = (void *)nlh + min_len; 179 int attrlen = nlh->nlmsg_len - min_len; 180 __u8 subsys_id = NFNL_SUBSYS_ID(type); 181 182 err = nla_parse(cda, ss->cb[cb_id].attr_count, 183 attr, attrlen, ss->cb[cb_id].policy); 184 if (err < 0) { 185 rcu_read_unlock(); 186 return err; 187 } 188 189 if (nc->call_rcu) { 190 err = nc->call_rcu(net->nfnl, skb, nlh, 191 (const struct nlattr **)cda); 192 rcu_read_unlock(); 193 } else { 194 rcu_read_unlock(); 195 nfnl_lock(subsys_id); 196 if (rcu_dereference_protected(table[subsys_id].subsys, 197 lockdep_is_held(&table[subsys_id].mutex)) != ss || 198 nfnetlink_find_client(type, ss) != nc) 199 err = -EAGAIN; 200 else if (nc->call) 201 err = nc->call(net->nfnl, skb, nlh, 202 (const struct nlattr **)cda); 203 else 204 err = -EINVAL; 205 nfnl_unlock(subsys_id); 206 } 207 if (err == -EAGAIN) 208 goto replay; 209 return err; 210 } 211 } 212 213 static void nfnetlink_rcv(struct sk_buff *skb) 214 { 215 netlink_rcv_skb(skb, &nfnetlink_rcv_msg); 216 } 217 218 #ifdef CONFIG_MODULES 219 static void nfnetlink_bind(int group) 220 { 221 const struct nfnetlink_subsystem *ss; 222 int type = nfnl_group2type[group]; 223 224 rcu_read_lock(); 225 ss = nfnetlink_get_subsys(type); 226 if (!ss) { 227 rcu_read_unlock(); 228 request_module("nfnetlink-subsys-%d", type); 229 return; 230 } 231 rcu_read_unlock(); 232 } 233 #endif 234 235 static int __net_init nfnetlink_net_init(struct net *net) 236 { 237 struct sock *nfnl; 238 struct netlink_kernel_cfg cfg = { 239 .groups = NFNLGRP_MAX, 240 .input = nfnetlink_rcv, 241 #ifdef CONFIG_MODULES 242 .bind = nfnetlink_bind, 243 #endif 244 }; 245 246 nfnl = netlink_kernel_create(net, NETLINK_NETFILTER, &cfg); 247 if (!nfnl) 248 return -ENOMEM; 249 net->nfnl_stash = nfnl; 250 rcu_assign_pointer(net->nfnl, nfnl); 251 return 0; 252 } 253 254 static void __net_exit nfnetlink_net_exit_batch(struct list_head *net_exit_list) 255 { 256 struct net *net; 257 258 list_for_each_entry(net, net_exit_list, exit_list) 259 RCU_INIT_POINTER(net->nfnl, NULL); 260 synchronize_net(); 261 list_for_each_entry(net, net_exit_list, exit_list) 262 netlink_kernel_release(net->nfnl_stash); 263 } 264 265 static struct pernet_operations nfnetlink_net_ops = { 266 .init = nfnetlink_net_init, 267 .exit_batch = nfnetlink_net_exit_batch, 268 }; 269 270 static int __init nfnetlink_init(void) 271 { 272 int i; 273 274 for (i=0; i<NFNL_SUBSYS_COUNT; i++) 275 mutex_init(&table[i].mutex); 276 277 pr_info("Netfilter messages via NETLINK v%s.\n", nfversion); 278 return register_pernet_subsys(&nfnetlink_net_ops); 279 } 280 281 static void __exit nfnetlink_exit(void) 282 { 283 pr_info("Removing netfilter NETLINK layer.\n"); 284 unregister_pernet_subsys(&nfnetlink_net_ops); 285 } 286 module_init(nfnetlink_init); 287 module_exit(nfnetlink_exit); 288