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1/*
2 * Rusty Russell (C)2000 -- This code is GPL.
3 * Patrick McHardy (c) 2006-2012
4 */
5
6#include <linux/kernel.h>
7#include <linux/slab.h>
8#include <linux/init.h>
9#include <linux/module.h>
10#include <linux/proc_fs.h>
11#include <linux/skbuff.h>
12#include <linux/netfilter.h>
13#include <linux/netfilter_bridge.h>
14#include <linux/seq_file.h>
15#include <linux/rcupdate.h>
16#include <net/protocol.h>
17#include <net/netfilter/nf_queue.h>
18#include <net/dst.h>
19
20#include "nf_internals.h"
21
22/*
23 * Hook for nfnetlink_queue to register its queue handler.
24 * We do this so that most of the NFQUEUE code can be modular.
25 *
26 * Once the queue is registered it must reinject all packets it
27 * receives, no matter what.
28 */
29
30/* return EBUSY when somebody else is registered, return EEXIST if the
31 * same handler is registered, return 0 in case of success. */
32void nf_register_queue_handler(struct net *net, const struct nf_queue_handler *qh)
33{
34 /* should never happen, we only have one queueing backend in kernel */
35 WARN_ON(rcu_access_pointer(net->nf.queue_handler));
36 rcu_assign_pointer(net->nf.queue_handler, qh);
37}
38EXPORT_SYMBOL(nf_register_queue_handler);
39
40/* The caller must flush their queue before this */
41void nf_unregister_queue_handler(struct net *net)
42{
43 RCU_INIT_POINTER(net->nf.queue_handler, NULL);
44}
45EXPORT_SYMBOL(nf_unregister_queue_handler);
46
47void nf_queue_entry_release_refs(struct nf_queue_entry *entry)
48{
49 struct nf_hook_state *state = &entry->state;
50
51 /* Release those devices we held, or Alexey will kill me. */
52 if (state->in)
53 dev_put(state->in);
54 if (state->out)
55 dev_put(state->out);
56 if (state->sk)
57 sock_put(state->sk);
58#if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
59 if (entry->skb->nf_bridge) {
60 struct net_device *physdev;
61
62 physdev = nf_bridge_get_physindev(entry->skb);
63 if (physdev)
64 dev_put(physdev);
65 physdev = nf_bridge_get_physoutdev(entry->skb);
66 if (physdev)
67 dev_put(physdev);
68 }
69#endif
70}
71EXPORT_SYMBOL_GPL(nf_queue_entry_release_refs);
72
73/* Bump dev refs so they don't vanish while packet is out */
74void nf_queue_entry_get_refs(struct nf_queue_entry *entry)
75{
76 struct nf_hook_state *state = &entry->state;
77
78 if (state->in)
79 dev_hold(state->in);
80 if (state->out)
81 dev_hold(state->out);
82 if (state->sk)
83 sock_hold(state->sk);
84#if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
85 if (entry->skb->nf_bridge) {
86 struct net_device *physdev;
87
88 physdev = nf_bridge_get_physindev(entry->skb);
89 if (physdev)
90 dev_hold(physdev);
91 physdev = nf_bridge_get_physoutdev(entry->skb);
92 if (physdev)
93 dev_hold(physdev);
94 }
95#endif
96}
97EXPORT_SYMBOL_GPL(nf_queue_entry_get_refs);
98
99void nf_queue_nf_hook_drop(struct net *net, const struct nf_hook_entry *entry)
100{
101 const struct nf_queue_handler *qh;
102
103 rcu_read_lock();
104 qh = rcu_dereference(net->nf.queue_handler);
105 if (qh)
106 qh->nf_hook_drop(net, entry);
107 rcu_read_unlock();
108}
109
110static int __nf_queue(struct sk_buff *skb, const struct nf_hook_state *state,
111 struct nf_hook_entry *hook_entry, unsigned int queuenum)
112{
113 int status = -ENOENT;
114 struct nf_queue_entry *entry = NULL;
115 const struct nf_afinfo *afinfo;
116 const struct nf_queue_handler *qh;
117 struct net *net = state->net;
118
119 /* QUEUE == DROP if no one is waiting, to be safe. */
120 qh = rcu_dereference(net->nf.queue_handler);
121 if (!qh) {
122 status = -ESRCH;
123 goto err;
124 }
125
126 afinfo = nf_get_afinfo(state->pf);
127 if (!afinfo)
128 goto err;
129
130 entry = kmalloc(sizeof(*entry) + afinfo->route_key_size, GFP_ATOMIC);
131 if (!entry) {
132 status = -ENOMEM;
133 goto err;
134 }
135
136 *entry = (struct nf_queue_entry) {
137 .skb = skb,
138 .state = *state,
139 .hook = hook_entry,
140 .size = sizeof(*entry) + afinfo->route_key_size,
141 };
142
143 nf_queue_entry_get_refs(entry);
144 skb_dst_force(skb);
145 afinfo->saveroute(skb, entry);
146 status = qh->outfn(entry, queuenum);
147
148 if (status < 0) {
149 nf_queue_entry_release_refs(entry);
150 goto err;
151 }
152
153 return 0;
154
155err:
156 kfree(entry);
157 return status;
158}
159
160/* Packets leaving via this function must come back through nf_reinject(). */
161int nf_queue(struct sk_buff *skb, struct nf_hook_state *state,
162 struct nf_hook_entry **entryp, unsigned int verdict)
163{
164 struct nf_hook_entry *entry = *entryp;
165 int ret;
166
167 ret = __nf_queue(skb, state, entry, verdict >> NF_VERDICT_QBITS);
168 if (ret < 0) {
169 if (ret == -ESRCH &&
170 (verdict & NF_VERDICT_FLAG_QUEUE_BYPASS)) {
171 *entryp = rcu_dereference(entry->next);
172 return 1;
173 }
174 kfree_skb(skb);
175 }
176
177 return 0;
178}
179
180static unsigned int nf_iterate(struct sk_buff *skb,
181 struct nf_hook_state *state,
182 struct nf_hook_entry **entryp)
183{
184 unsigned int verdict;
185
186 do {
187repeat:
188 verdict = nf_hook_entry_hookfn((*entryp), skb, state);
189 if (verdict != NF_ACCEPT) {
190 if (verdict != NF_REPEAT)
191 return verdict;
192 goto repeat;
193 }
194 *entryp = rcu_dereference((*entryp)->next);
195 } while (*entryp);
196
197 return NF_ACCEPT;
198}
199
200void nf_reinject(struct nf_queue_entry *entry, unsigned int verdict)
201{
202 struct nf_hook_entry *hook_entry = entry->hook;
203 struct sk_buff *skb = entry->skb;
204 const struct nf_afinfo *afinfo;
205 int err;
206
207 nf_queue_entry_release_refs(entry);
208
209 /* Continue traversal iff userspace said ok... */
210 if (verdict == NF_REPEAT)
211 verdict = nf_hook_entry_hookfn(hook_entry, skb, &entry->state);
212
213 if (verdict == NF_ACCEPT) {
214 afinfo = nf_get_afinfo(entry->state.pf);
215 if (!afinfo || afinfo->reroute(entry->state.net, skb, entry) < 0)
216 verdict = NF_DROP;
217 }
218
219 if (verdict == NF_ACCEPT) {
220 hook_entry = rcu_dereference(hook_entry->next);
221 if (hook_entry)
222next_hook:
223 verdict = nf_iterate(skb, &entry->state, &hook_entry);
224 }
225
226 switch (verdict & NF_VERDICT_MASK) {
227 case NF_ACCEPT:
228 case NF_STOP:
229okfn:
230 local_bh_disable();
231 entry->state.okfn(entry->state.net, entry->state.sk, skb);
232 local_bh_enable();
233 break;
234 case NF_QUEUE:
235 err = nf_queue(skb, &entry->state, &hook_entry, verdict);
236 if (err == 1) {
237 if (hook_entry)
238 goto next_hook;
239 goto okfn;
240 }
241 break;
242 case NF_STOLEN:
243 break;
244 default:
245 kfree_skb(skb);
246 }
247
248 kfree(entry);
249}
250EXPORT_SYMBOL(nf_reinject);
1#include <linux/kernel.h>
2#include <linux/slab.h>
3#include <linux/init.h>
4#include <linux/module.h>
5#include <linux/proc_fs.h>
6#include <linux/skbuff.h>
7#include <linux/netfilter.h>
8#include <linux/seq_file.h>
9#include <linux/rcupdate.h>
10#include <net/protocol.h>
11#include <net/netfilter/nf_queue.h>
12#include <net/dst.h>
13
14#include "nf_internals.h"
15
16/*
17 * A queue handler may be registered for each protocol. Each is protected by
18 * long term mutex. The handler must provide an an outfn() to accept packets
19 * for queueing and must reinject all packets it receives, no matter what.
20 */
21static const struct nf_queue_handler __rcu *queue_handler[NFPROTO_NUMPROTO] __read_mostly;
22
23static DEFINE_MUTEX(queue_handler_mutex);
24
25/* return EBUSY when somebody else is registered, return EEXIST if the
26 * same handler is registered, return 0 in case of success. */
27int nf_register_queue_handler(u_int8_t pf, const struct nf_queue_handler *qh)
28{
29 int ret;
30 const struct nf_queue_handler *old;
31
32 if (pf >= ARRAY_SIZE(queue_handler))
33 return -EINVAL;
34
35 mutex_lock(&queue_handler_mutex);
36 old = rcu_dereference_protected(queue_handler[pf],
37 lockdep_is_held(&queue_handler_mutex));
38 if (old == qh)
39 ret = -EEXIST;
40 else if (old)
41 ret = -EBUSY;
42 else {
43 rcu_assign_pointer(queue_handler[pf], qh);
44 ret = 0;
45 }
46 mutex_unlock(&queue_handler_mutex);
47
48 return ret;
49}
50EXPORT_SYMBOL(nf_register_queue_handler);
51
52/* The caller must flush their queue before this */
53int nf_unregister_queue_handler(u_int8_t pf, const struct nf_queue_handler *qh)
54{
55 const struct nf_queue_handler *old;
56
57 if (pf >= ARRAY_SIZE(queue_handler))
58 return -EINVAL;
59
60 mutex_lock(&queue_handler_mutex);
61 old = rcu_dereference_protected(queue_handler[pf],
62 lockdep_is_held(&queue_handler_mutex));
63 if (old && old != qh) {
64 mutex_unlock(&queue_handler_mutex);
65 return -EINVAL;
66 }
67
68 RCU_INIT_POINTER(queue_handler[pf], NULL);
69 mutex_unlock(&queue_handler_mutex);
70
71 synchronize_rcu();
72
73 return 0;
74}
75EXPORT_SYMBOL(nf_unregister_queue_handler);
76
77void nf_unregister_queue_handlers(const struct nf_queue_handler *qh)
78{
79 u_int8_t pf;
80
81 mutex_lock(&queue_handler_mutex);
82 for (pf = 0; pf < ARRAY_SIZE(queue_handler); pf++) {
83 if (rcu_dereference_protected(
84 queue_handler[pf],
85 lockdep_is_held(&queue_handler_mutex)
86 ) == qh)
87 RCU_INIT_POINTER(queue_handler[pf], NULL);
88 }
89 mutex_unlock(&queue_handler_mutex);
90
91 synchronize_rcu();
92}
93EXPORT_SYMBOL_GPL(nf_unregister_queue_handlers);
94
95static void nf_queue_entry_release_refs(struct nf_queue_entry *entry)
96{
97 /* Release those devices we held, or Alexey will kill me. */
98 if (entry->indev)
99 dev_put(entry->indev);
100 if (entry->outdev)
101 dev_put(entry->outdev);
102#ifdef CONFIG_BRIDGE_NETFILTER
103 if (entry->skb->nf_bridge) {
104 struct nf_bridge_info *nf_bridge = entry->skb->nf_bridge;
105
106 if (nf_bridge->physindev)
107 dev_put(nf_bridge->physindev);
108 if (nf_bridge->physoutdev)
109 dev_put(nf_bridge->physoutdev);
110 }
111#endif
112 /* Drop reference to owner of hook which queued us. */
113 module_put(entry->elem->owner);
114}
115
116/*
117 * Any packet that leaves via this function must come back
118 * through nf_reinject().
119 */
120static int __nf_queue(struct sk_buff *skb,
121 struct list_head *elem,
122 u_int8_t pf, unsigned int hook,
123 struct net_device *indev,
124 struct net_device *outdev,
125 int (*okfn)(struct sk_buff *),
126 unsigned int queuenum)
127{
128 int status = -ENOENT;
129 struct nf_queue_entry *entry = NULL;
130#ifdef CONFIG_BRIDGE_NETFILTER
131 struct net_device *physindev;
132 struct net_device *physoutdev;
133#endif
134 const struct nf_afinfo *afinfo;
135 const struct nf_queue_handler *qh;
136
137 /* QUEUE == DROP if no one is waiting, to be safe. */
138 rcu_read_lock();
139
140 qh = rcu_dereference(queue_handler[pf]);
141 if (!qh) {
142 status = -ESRCH;
143 goto err_unlock;
144 }
145
146 afinfo = nf_get_afinfo(pf);
147 if (!afinfo)
148 goto err_unlock;
149
150 entry = kmalloc(sizeof(*entry) + afinfo->route_key_size, GFP_ATOMIC);
151 if (!entry) {
152 status = -ENOMEM;
153 goto err_unlock;
154 }
155
156 *entry = (struct nf_queue_entry) {
157 .skb = skb,
158 .elem = list_entry(elem, struct nf_hook_ops, list),
159 .pf = pf,
160 .hook = hook,
161 .indev = indev,
162 .outdev = outdev,
163 .okfn = okfn,
164 };
165
166 /* If it's going away, ignore hook. */
167 if (!try_module_get(entry->elem->owner)) {
168 status = -ECANCELED;
169 goto err_unlock;
170 }
171 /* Bump dev refs so they don't vanish while packet is out */
172 if (indev)
173 dev_hold(indev);
174 if (outdev)
175 dev_hold(outdev);
176#ifdef CONFIG_BRIDGE_NETFILTER
177 if (skb->nf_bridge) {
178 physindev = skb->nf_bridge->physindev;
179 if (physindev)
180 dev_hold(physindev);
181 physoutdev = skb->nf_bridge->physoutdev;
182 if (physoutdev)
183 dev_hold(physoutdev);
184 }
185#endif
186 skb_dst_force(skb);
187 afinfo->saveroute(skb, entry);
188 status = qh->outfn(entry, queuenum);
189
190 rcu_read_unlock();
191
192 if (status < 0) {
193 nf_queue_entry_release_refs(entry);
194 goto err;
195 }
196
197 return 0;
198
199err_unlock:
200 rcu_read_unlock();
201err:
202 kfree(entry);
203 return status;
204}
205
206#ifdef CONFIG_BRIDGE_NETFILTER
207/* When called from bridge netfilter, skb->data must point to MAC header
208 * before calling skb_gso_segment(). Else, original MAC header is lost
209 * and segmented skbs will be sent to wrong destination.
210 */
211static void nf_bridge_adjust_skb_data(struct sk_buff *skb)
212{
213 if (skb->nf_bridge)
214 __skb_push(skb, skb->network_header - skb->mac_header);
215}
216
217static void nf_bridge_adjust_segmented_data(struct sk_buff *skb)
218{
219 if (skb->nf_bridge)
220 __skb_pull(skb, skb->network_header - skb->mac_header);
221}
222#else
223#define nf_bridge_adjust_skb_data(s) do {} while (0)
224#define nf_bridge_adjust_segmented_data(s) do {} while (0)
225#endif
226
227int nf_queue(struct sk_buff *skb,
228 struct list_head *elem,
229 u_int8_t pf, unsigned int hook,
230 struct net_device *indev,
231 struct net_device *outdev,
232 int (*okfn)(struct sk_buff *),
233 unsigned int queuenum)
234{
235 struct sk_buff *segs;
236 int err = -EINVAL;
237 unsigned int queued;
238
239 if (!skb_is_gso(skb))
240 return __nf_queue(skb, elem, pf, hook, indev, outdev, okfn,
241 queuenum);
242
243 switch (pf) {
244 case NFPROTO_IPV4:
245 skb->protocol = htons(ETH_P_IP);
246 break;
247 case NFPROTO_IPV6:
248 skb->protocol = htons(ETH_P_IPV6);
249 break;
250 }
251
252 nf_bridge_adjust_skb_data(skb);
253 segs = skb_gso_segment(skb, 0);
254 /* Does not use PTR_ERR to limit the number of error codes that can be
255 * returned by nf_queue. For instance, callers rely on -ECANCELED to mean
256 * 'ignore this hook'.
257 */
258 if (IS_ERR(segs))
259 goto out_err;
260 queued = 0;
261 err = 0;
262 do {
263 struct sk_buff *nskb = segs->next;
264
265 segs->next = NULL;
266 if (err == 0) {
267 nf_bridge_adjust_segmented_data(segs);
268 err = __nf_queue(segs, elem, pf, hook, indev,
269 outdev, okfn, queuenum);
270 }
271 if (err == 0)
272 queued++;
273 else
274 kfree_skb(segs);
275 segs = nskb;
276 } while (segs);
277
278 if (queued) {
279 kfree_skb(skb);
280 return 0;
281 }
282 out_err:
283 nf_bridge_adjust_segmented_data(skb);
284 return err;
285}
286
287void nf_reinject(struct nf_queue_entry *entry, unsigned int verdict)
288{
289 struct sk_buff *skb = entry->skb;
290 struct list_head *elem = &entry->elem->list;
291 const struct nf_afinfo *afinfo;
292 int err;
293
294 rcu_read_lock();
295
296 nf_queue_entry_release_refs(entry);
297
298 /* Continue traversal iff userspace said ok... */
299 if (verdict == NF_REPEAT) {
300 elem = elem->prev;
301 verdict = NF_ACCEPT;
302 }
303
304 if (verdict == NF_ACCEPT) {
305 afinfo = nf_get_afinfo(entry->pf);
306 if (!afinfo || afinfo->reroute(skb, entry) < 0)
307 verdict = NF_DROP;
308 }
309
310 if (verdict == NF_ACCEPT) {
311 next_hook:
312 verdict = nf_iterate(&nf_hooks[entry->pf][entry->hook],
313 skb, entry->hook,
314 entry->indev, entry->outdev, &elem,
315 entry->okfn, INT_MIN);
316 }
317
318 switch (verdict & NF_VERDICT_MASK) {
319 case NF_ACCEPT:
320 case NF_STOP:
321 local_bh_disable();
322 entry->okfn(skb);
323 local_bh_enable();
324 break;
325 case NF_QUEUE:
326 err = __nf_queue(skb, elem, entry->pf, entry->hook,
327 entry->indev, entry->outdev, entry->okfn,
328 verdict >> NF_VERDICT_QBITS);
329 if (err < 0) {
330 if (err == -ECANCELED)
331 goto next_hook;
332 if (err == -ESRCH &&
333 (verdict & NF_VERDICT_FLAG_QUEUE_BYPASS))
334 goto next_hook;
335 kfree_skb(skb);
336 }
337 break;
338 case NF_STOLEN:
339 break;
340 default:
341 kfree_skb(skb);
342 }
343 rcu_read_unlock();
344 kfree(entry);
345}
346EXPORT_SYMBOL(nf_reinject);
347
348#ifdef CONFIG_PROC_FS
349static void *seq_start(struct seq_file *seq, loff_t *pos)
350{
351 if (*pos >= ARRAY_SIZE(queue_handler))
352 return NULL;
353
354 return pos;
355}
356
357static void *seq_next(struct seq_file *s, void *v, loff_t *pos)
358{
359 (*pos)++;
360
361 if (*pos >= ARRAY_SIZE(queue_handler))
362 return NULL;
363
364 return pos;
365}
366
367static void seq_stop(struct seq_file *s, void *v)
368{
369
370}
371
372static int seq_show(struct seq_file *s, void *v)
373{
374 int ret;
375 loff_t *pos = v;
376 const struct nf_queue_handler *qh;
377
378 rcu_read_lock();
379 qh = rcu_dereference(queue_handler[*pos]);
380 if (!qh)
381 ret = seq_printf(s, "%2lld NONE\n", *pos);
382 else
383 ret = seq_printf(s, "%2lld %s\n", *pos, qh->name);
384 rcu_read_unlock();
385
386 return ret;
387}
388
389static const struct seq_operations nfqueue_seq_ops = {
390 .start = seq_start,
391 .next = seq_next,
392 .stop = seq_stop,
393 .show = seq_show,
394};
395
396static int nfqueue_open(struct inode *inode, struct file *file)
397{
398 return seq_open(file, &nfqueue_seq_ops);
399}
400
401static const struct file_operations nfqueue_file_ops = {
402 .owner = THIS_MODULE,
403 .open = nfqueue_open,
404 .read = seq_read,
405 .llseek = seq_lseek,
406 .release = seq_release,
407};
408#endif /* PROC_FS */
409
410
411int __init netfilter_queue_init(void)
412{
413#ifdef CONFIG_PROC_FS
414 if (!proc_create("nf_queue", S_IRUGO,
415 proc_net_netfilter, &nfqueue_file_ops))
416 return -1;
417#endif
418 return 0;
419}
420