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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 | #ifdef CONFIG_PROVE_LOCKING |
65 | int lockdep_nfnl_is_held(u8 subsys_id) |
66 | { |
67 | return lockdep_is_held(&table[subsys_id].mutex); |
68 | } |
69 | EXPORT_SYMBOL_GPL(lockdep_nfnl_is_held); |
70 | #endif |
71 | |
72 | int nfnetlink_subsys_register(const struct nfnetlink_subsystem *n) |
73 | { |
74 | nfnl_lock(n->subsys_id); |
75 | if (table[n->subsys_id].subsys) { |
76 | nfnl_unlock(n->subsys_id); |
77 | return -EBUSY; |
78 | } |
79 | rcu_assign_pointer(table[n->subsys_id].subsys, n); |
80 | nfnl_unlock(n->subsys_id); |
81 | |
82 | return 0; |
83 | } |
84 | EXPORT_SYMBOL_GPL(nfnetlink_subsys_register); |
85 | |
86 | int nfnetlink_subsys_unregister(const struct nfnetlink_subsystem *n) |
87 | { |
88 | nfnl_lock(n->subsys_id); |
89 | table[n->subsys_id].subsys = NULL; |
90 | nfnl_unlock(n->subsys_id); |
91 | synchronize_rcu(); |
92 | return 0; |
93 | } |
94 | EXPORT_SYMBOL_GPL(nfnetlink_subsys_unregister); |
95 | |
96 | static inline const struct nfnetlink_subsystem *nfnetlink_get_subsys(u_int16_t type) |
97 | { |
98 | u_int8_t subsys_id = NFNL_SUBSYS_ID(type); |
99 | |
100 | if (subsys_id >= NFNL_SUBSYS_COUNT) |
101 | return NULL; |
102 | |
103 | return rcu_dereference(table[subsys_id].subsys); |
104 | } |
105 | |
106 | static inline const struct nfnl_callback * |
107 | nfnetlink_find_client(u_int16_t type, const struct nfnetlink_subsystem *ss) |
108 | { |
109 | u_int8_t cb_id = NFNL_MSG_TYPE(type); |
110 | |
111 | if (cb_id >= ss->cb_count) |
112 | return NULL; |
113 | |
114 | return &ss->cb[cb_id]; |
115 | } |
116 | |
117 | int nfnetlink_has_listeners(struct net *net, unsigned int group) |
118 | { |
119 | return netlink_has_listeners(net->nfnl, group); |
120 | } |
121 | EXPORT_SYMBOL_GPL(nfnetlink_has_listeners); |
122 | |
123 | struct sk_buff *nfnetlink_alloc_skb(struct net *net, unsigned int size, |
124 | u32 dst_portid, gfp_t gfp_mask) |
125 | { |
126 | return netlink_alloc_skb(net->nfnl, size, dst_portid, gfp_mask); |
127 | } |
128 | EXPORT_SYMBOL_GPL(nfnetlink_alloc_skb); |
129 | |
130 | int nfnetlink_send(struct sk_buff *skb, struct net *net, u32 portid, |
131 | unsigned int group, int echo, gfp_t flags) |
132 | { |
133 | return nlmsg_notify(net->nfnl, skb, portid, group, echo, flags); |
134 | } |
135 | EXPORT_SYMBOL_GPL(nfnetlink_send); |
136 | |
137 | int nfnetlink_set_err(struct net *net, u32 portid, u32 group, int error) |
138 | { |
139 | return netlink_set_err(net->nfnl, portid, group, error); |
140 | } |
141 | EXPORT_SYMBOL_GPL(nfnetlink_set_err); |
142 | |
143 | int nfnetlink_unicast(struct sk_buff *skb, struct net *net, u32 portid, |
144 | int flags) |
145 | { |
146 | return netlink_unicast(net->nfnl, skb, portid, flags); |
147 | } |
148 | EXPORT_SYMBOL_GPL(nfnetlink_unicast); |
149 | |
150 | /* Process one complete nfnetlink message. */ |
151 | static int nfnetlink_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh) |
152 | { |
153 | struct net *net = sock_net(skb->sk); |
154 | const struct nfnl_callback *nc; |
155 | const struct nfnetlink_subsystem *ss; |
156 | int type, err; |
157 | |
158 | /* All the messages must at least contain nfgenmsg */ |
159 | if (nlmsg_len(nlh) < sizeof(struct nfgenmsg)) |
160 | return 0; |
161 | |
162 | type = nlh->nlmsg_type; |
163 | replay: |
164 | rcu_read_lock(); |
165 | ss = nfnetlink_get_subsys(type); |
166 | if (!ss) { |
167 | #ifdef CONFIG_MODULES |
168 | rcu_read_unlock(); |
169 | request_module("nfnetlink-subsys-%d", NFNL_SUBSYS_ID(type)); |
170 | rcu_read_lock(); |
171 | ss = nfnetlink_get_subsys(type); |
172 | if (!ss) |
173 | #endif |
174 | { |
175 | rcu_read_unlock(); |
176 | return -EINVAL; |
177 | } |
178 | } |
179 | |
180 | nc = nfnetlink_find_client(type, ss); |
181 | if (!nc) { |
182 | rcu_read_unlock(); |
183 | return -EINVAL; |
184 | } |
185 | |
186 | { |
187 | int min_len = nlmsg_total_size(sizeof(struct nfgenmsg)); |
188 | u_int8_t cb_id = NFNL_MSG_TYPE(nlh->nlmsg_type); |
189 | struct nlattr *cda[ss->cb[cb_id].attr_count + 1]; |
190 | struct nlattr *attr = (void *)nlh + min_len; |
191 | int attrlen = nlh->nlmsg_len - min_len; |
192 | __u8 subsys_id = NFNL_SUBSYS_ID(type); |
193 | |
194 | err = nla_parse(cda, ss->cb[cb_id].attr_count, |
195 | attr, attrlen, ss->cb[cb_id].policy); |
196 | if (err < 0) { |
197 | rcu_read_unlock(); |
198 | return err; |
199 | } |
200 | |
201 | if (nc->call_rcu) { |
202 | err = nc->call_rcu(net->nfnl, skb, nlh, |
203 | (const struct nlattr **)cda); |
204 | rcu_read_unlock(); |
205 | } else { |
206 | rcu_read_unlock(); |
207 | nfnl_lock(subsys_id); |
208 | if (rcu_dereference_protected(table[subsys_id].subsys, |
209 | lockdep_is_held(&table[subsys_id].mutex)) != ss || |
210 | nfnetlink_find_client(type, ss) != nc) |
211 | err = -EAGAIN; |
212 | else if (nc->call) |
213 | err = nc->call(net->nfnl, skb, nlh, |
214 | (const struct nlattr **)cda); |
215 | else |
216 | err = -EINVAL; |
217 | nfnl_unlock(subsys_id); |
218 | } |
219 | if (err == -EAGAIN) |
220 | goto replay; |
221 | return err; |
222 | } |
223 | } |
224 | |
225 | static void nfnetlink_rcv_batch(struct sk_buff *skb, struct nlmsghdr *nlh, |
226 | u_int16_t subsys_id) |
227 | { |
228 | struct sk_buff *nskb, *oskb = skb; |
229 | struct net *net = sock_net(skb->sk); |
230 | const struct nfnetlink_subsystem *ss; |
231 | const struct nfnl_callback *nc; |
232 | bool success = true, done = false; |
233 | int err; |
234 | |
235 | if (subsys_id >= NFNL_SUBSYS_COUNT) |
236 | return netlink_ack(skb, nlh, -EINVAL); |
237 | replay: |
238 | nskb = netlink_skb_clone(oskb, GFP_KERNEL); |
239 | if (!nskb) |
240 | return netlink_ack(oskb, nlh, -ENOMEM); |
241 | |
242 | nskb->sk = oskb->sk; |
243 | skb = nskb; |
244 | |
245 | nfnl_lock(subsys_id); |
246 | ss = rcu_dereference_protected(table[subsys_id].subsys, |
247 | lockdep_is_held(&table[subsys_id].mutex)); |
248 | if (!ss) { |
249 | #ifdef CONFIG_MODULES |
250 | nfnl_unlock(subsys_id); |
251 | request_module("nfnetlink-subsys-%d", subsys_id); |
252 | nfnl_lock(subsys_id); |
253 | ss = rcu_dereference_protected(table[subsys_id].subsys, |
254 | lockdep_is_held(&table[subsys_id].mutex)); |
255 | if (!ss) |
256 | #endif |
257 | { |
258 | nfnl_unlock(subsys_id); |
259 | netlink_ack(skb, nlh, -EOPNOTSUPP); |
260 | return kfree_skb(nskb); |
261 | } |
262 | } |
263 | |
264 | if (!ss->commit || !ss->abort) { |
265 | nfnl_unlock(subsys_id); |
266 | netlink_ack(skb, nlh, -EOPNOTSUPP); |
267 | return kfree_skb(skb); |
268 | } |
269 | |
270 | while (skb->len >= nlmsg_total_size(0)) { |
271 | int msglen, type; |
272 | |
273 | nlh = nlmsg_hdr(skb); |
274 | err = 0; |
275 | |
276 | if (nlh->nlmsg_len < NLMSG_HDRLEN) { |
277 | err = -EINVAL; |
278 | goto ack; |
279 | } |
280 | |
281 | /* Only requests are handled by the kernel */ |
282 | if (!(nlh->nlmsg_flags & NLM_F_REQUEST)) { |
283 | err = -EINVAL; |
284 | goto ack; |
285 | } |
286 | |
287 | type = nlh->nlmsg_type; |
288 | if (type == NFNL_MSG_BATCH_BEGIN) { |
289 | /* Malformed: Batch begin twice */ |
290 | success = false; |
291 | goto done; |
292 | } else if (type == NFNL_MSG_BATCH_END) { |
293 | done = true; |
294 | goto done; |
295 | } else if (type < NLMSG_MIN_TYPE) { |
296 | err = -EINVAL; |
297 | goto ack; |
298 | } |
299 | |
300 | /* We only accept a batch with messages for the same |
301 | * subsystem. |
302 | */ |
303 | if (NFNL_SUBSYS_ID(type) != subsys_id) { |
304 | err = -EINVAL; |
305 | goto ack; |
306 | } |
307 | |
308 | nc = nfnetlink_find_client(type, ss); |
309 | if (!nc) { |
310 | err = -EINVAL; |
311 | goto ack; |
312 | } |
313 | |
314 | { |
315 | int min_len = nlmsg_total_size(sizeof(struct nfgenmsg)); |
316 | u_int8_t cb_id = NFNL_MSG_TYPE(nlh->nlmsg_type); |
317 | struct nlattr *cda[ss->cb[cb_id].attr_count + 1]; |
318 | struct nlattr *attr = (void *)nlh + min_len; |
319 | int attrlen = nlh->nlmsg_len - min_len; |
320 | |
321 | err = nla_parse(cda, ss->cb[cb_id].attr_count, |
322 | attr, attrlen, ss->cb[cb_id].policy); |
323 | if (err < 0) |
324 | goto ack; |
325 | |
326 | if (nc->call_batch) { |
327 | err = nc->call_batch(net->nfnl, skb, nlh, |
328 | (const struct nlattr **)cda); |
329 | } |
330 | |
331 | /* The lock was released to autoload some module, we |
332 | * have to abort and start from scratch using the |
333 | * original skb. |
334 | */ |
335 | if (err == -EAGAIN) { |
336 | ss->abort(skb); |
337 | nfnl_unlock(subsys_id); |
338 | kfree_skb(nskb); |
339 | goto replay; |
340 | } |
341 | } |
342 | ack: |
343 | if (nlh->nlmsg_flags & NLM_F_ACK || err) { |
344 | /* We don't stop processing the batch on errors, thus, |
345 | * userspace gets all the errors that the batch |
346 | * triggers. |
347 | */ |
348 | netlink_ack(skb, nlh, err); |
349 | if (err) |
350 | success = false; |
351 | } |
352 | |
353 | msglen = NLMSG_ALIGN(nlh->nlmsg_len); |
354 | if (msglen > skb->len) |
355 | msglen = skb->len; |
356 | skb_pull(skb, msglen); |
357 | } |
358 | done: |
359 | if (success && done) |
360 | ss->commit(skb); |
361 | else |
362 | ss->abort(skb); |
363 | |
364 | nfnl_unlock(subsys_id); |
365 | kfree_skb(nskb); |
366 | } |
367 | |
368 | static void nfnetlink_rcv(struct sk_buff *skb) |
369 | { |
370 | struct nlmsghdr *nlh = nlmsg_hdr(skb); |
371 | int msglen; |
372 | |
373 | if (nlh->nlmsg_len < NLMSG_HDRLEN || |
374 | skb->len < nlh->nlmsg_len) |
375 | return; |
376 | |
377 | if (!netlink_net_capable(skb, CAP_NET_ADMIN)) { |
378 | netlink_ack(skb, nlh, -EPERM); |
379 | return; |
380 | } |
381 | |
382 | if (nlh->nlmsg_type == NFNL_MSG_BATCH_BEGIN) { |
383 | struct nfgenmsg *nfgenmsg; |
384 | |
385 | msglen = NLMSG_ALIGN(nlh->nlmsg_len); |
386 | if (msglen > skb->len) |
387 | msglen = skb->len; |
388 | |
389 | if (nlh->nlmsg_len < NLMSG_HDRLEN || |
390 | skb->len < NLMSG_HDRLEN + sizeof(struct nfgenmsg)) |
391 | return; |
392 | |
393 | nfgenmsg = nlmsg_data(nlh); |
394 | skb_pull(skb, msglen); |
395 | nfnetlink_rcv_batch(skb, nlh, nfgenmsg->res_id); |
396 | } else { |
397 | netlink_rcv_skb(skb, &nfnetlink_rcv_msg); |
398 | } |
399 | } |
400 | |
401 | #ifdef CONFIG_MODULES |
402 | static void nfnetlink_bind(int group) |
403 | { |
404 | const struct nfnetlink_subsystem *ss; |
405 | int type = nfnl_group2type[group]; |
406 | |
407 | rcu_read_lock(); |
408 | ss = nfnetlink_get_subsys(type); |
409 | if (!ss) { |
410 | rcu_read_unlock(); |
411 | request_module("nfnetlink-subsys-%d", type); |
412 | return; |
413 | } |
414 | rcu_read_unlock(); |
415 | } |
416 | #endif |
417 | |
418 | static int __net_init nfnetlink_net_init(struct net *net) |
419 | { |
420 | struct sock *nfnl; |
421 | struct netlink_kernel_cfg cfg = { |
422 | .groups = NFNLGRP_MAX, |
423 | .input = nfnetlink_rcv, |
424 | #ifdef CONFIG_MODULES |
425 | .bind = nfnetlink_bind, |
426 | #endif |
427 | }; |
428 | |
429 | nfnl = netlink_kernel_create(net, NETLINK_NETFILTER, &cfg); |
430 | if (!nfnl) |
431 | return -ENOMEM; |
432 | net->nfnl_stash = nfnl; |
433 | rcu_assign_pointer(net->nfnl, nfnl); |
434 | return 0; |
435 | } |
436 | |
437 | static void __net_exit nfnetlink_net_exit_batch(struct list_head *net_exit_list) |
438 | { |
439 | struct net *net; |
440 | |
441 | list_for_each_entry(net, net_exit_list, exit_list) |
442 | RCU_INIT_POINTER(net->nfnl, NULL); |
443 | synchronize_net(); |
444 | list_for_each_entry(net, net_exit_list, exit_list) |
445 | netlink_kernel_release(net->nfnl_stash); |
446 | } |
447 | |
448 | static struct pernet_operations nfnetlink_net_ops = { |
449 | .init = nfnetlink_net_init, |
450 | .exit_batch = nfnetlink_net_exit_batch, |
451 | }; |
452 | |
453 | static int __init nfnetlink_init(void) |
454 | { |
455 | int i; |
456 | |
457 | for (i=0; i<NFNL_SUBSYS_COUNT; i++) |
458 | mutex_init(&table[i].mutex); |
459 | |
460 | pr_info("Netfilter messages via NETLINK v%s.\n", nfversion); |
461 | return register_pernet_subsys(&nfnetlink_net_ops); |
462 | } |
463 | |
464 | static void __exit nfnetlink_exit(void) |
465 | { |
466 | pr_info("Removing netfilter NETLINK layer.\n"); |
467 | unregister_pernet_subsys(&nfnetlink_net_ops); |
468 | } |
469 | module_init(nfnetlink_init); |
470 | module_exit(nfnetlink_exit); |
471 |
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