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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
32MODULE_LICENSE("GPL");
33MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
34MODULE_ALIAS_NET_PF_PROTO(PF_NETLINK, NETLINK_NETFILTER);
35
36static char __initdata nfversion[] = "0.30";
37
38static struct {
39 struct mutex mutex;
40 const struct nfnetlink_subsystem __rcu *subsys;
41} table[NFNL_SUBSYS_COUNT];
42
43static 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
52void nfnl_lock(__u8 subsys_id)
53{
54 mutex_lock(&table[subsys_id].mutex);
55}
56EXPORT_SYMBOL_GPL(nfnl_lock);
57
58void nfnl_unlock(__u8 subsys_id)
59{
60 mutex_unlock(&table[subsys_id].mutex);
61}
62EXPORT_SYMBOL_GPL(nfnl_unlock);
63
64int 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}
76EXPORT_SYMBOL_GPL(nfnetlink_subsys_register);
77
78int 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}
86EXPORT_SYMBOL_GPL(nfnetlink_subsys_unregister);
87
88static 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
98static inline const struct nfnl_callback *
99nfnetlink_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
109int nfnetlink_has_listeners(struct net *net, unsigned int group)
110{
111 return netlink_has_listeners(net->nfnl, group);
112}
113EXPORT_SYMBOL_GPL(nfnetlink_has_listeners);
114
115struct 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}
120EXPORT_SYMBOL_GPL(nfnetlink_alloc_skb);
121
122int 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}
127EXPORT_SYMBOL_GPL(nfnetlink_send);
128
129int nfnetlink_set_err(struct net *net, u32 portid, u32 group, int error)
130{
131 return netlink_set_err(net->nfnl, portid, group, error);
132}
133EXPORT_SYMBOL_GPL(nfnetlink_set_err);
134
135int 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}
140EXPORT_SYMBOL_GPL(nfnetlink_unicast);
141
142
143static 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
154 if (nlmsg_len(nlh) < sizeof(struct nfgenmsg))
155 return 0;
156
157 type = nlh->nlmsg_type;
158replay:
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
220static void nfnetlink_rcv(struct sk_buff *skb)
221{
222 netlink_rcv_skb(skb, &nfnetlink_rcv_msg);
223}
224
225#ifdef CONFIG_MODULES
226static 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
242static 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
261static 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
272static struct pernet_operations nfnetlink_net_ops = {
273 .init = nfnetlink_net_init,
274 .exit_batch = nfnetlink_net_exit_batch,
275};
276
277static 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
288static void __exit nfnetlink_exit(void)
289{
290 pr_info("Removing netfilter NETLINK layer.\n");
291 unregister_pernet_subsys(&nfnetlink_net_ops);
292}
293module_init(nfnetlink_init);
294module_exit(nfnetlink_exit);
295
