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_ipv4.h>
14 #include <linux/netfilter_ipv6.h>
15 #include <linux/netfilter_bridge.h>
16 #include <linux/seq_file.h>
17 #include <linux/rcupdate.h>
18 #include <net/protocol.h>
19 #include <net/netfilter/nf_queue.h>
20 #include <net/dst.h>
21
22 #include "nf_internals.h"
23
24 /*
25 * Hook for nfnetlink_queue to register its queue handler.
26 * We do this so that most of the NFQUEUE code can be modular.
27 *
28 * Once the queue is registered it must reinject all packets it
29 * receives, no matter what.
30 */
31
32 /* return EBUSY when somebody else is registered, return EEXIST if the
33 * same handler is registered, return 0 in case of success. */
nf_register_queue_handler(struct net * net,const struct nf_queue_handler * qh)34 void nf_register_queue_handler(struct net *net, const struct nf_queue_handler *qh)
35 {
36 /* should never happen, we only have one queueing backend in kernel */
37 WARN_ON(rcu_access_pointer(net->nf.queue_handler));
38 rcu_assign_pointer(net->nf.queue_handler, qh);
39 }
40 EXPORT_SYMBOL(nf_register_queue_handler);
41
42 /* The caller must flush their queue before this */
nf_unregister_queue_handler(struct net * net)43 void nf_unregister_queue_handler(struct net *net)
44 {
45 RCU_INIT_POINTER(net->nf.queue_handler, NULL);
46 }
47 EXPORT_SYMBOL(nf_unregister_queue_handler);
48
nf_queue_entry_release_br_nf_refs(struct sk_buff * skb)49 static void nf_queue_entry_release_br_nf_refs(struct sk_buff *skb)
50 {
51 #if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
52 struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb);
53
54 if (nf_bridge) {
55 struct net_device *physdev;
56
57 physdev = nf_bridge_get_physindev(skb);
58 if (physdev)
59 dev_put(physdev);
60 physdev = nf_bridge_get_physoutdev(skb);
61 if (physdev)
62 dev_put(physdev);
63 }
64 #endif
65 }
66
nf_queue_entry_release_refs(struct nf_queue_entry * entry)67 void nf_queue_entry_release_refs(struct nf_queue_entry *entry)
68 {
69 struct nf_hook_state *state = &entry->state;
70
71 /* Release those devices we held, or Alexey will kill me. */
72 if (state->in)
73 dev_put(state->in);
74 if (state->out)
75 dev_put(state->out);
76 if (state->sk)
77 sock_put(state->sk);
78
79 nf_queue_entry_release_br_nf_refs(entry->skb);
80 }
81 EXPORT_SYMBOL_GPL(nf_queue_entry_release_refs);
82
nf_queue_entry_get_br_nf_refs(struct sk_buff * skb)83 static void nf_queue_entry_get_br_nf_refs(struct sk_buff *skb)
84 {
85 #if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
86 struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb);
87
88 if (nf_bridge) {
89 struct net_device *physdev;
90
91 physdev = nf_bridge_get_physindev(skb);
92 if (physdev)
93 dev_hold(physdev);
94 physdev = nf_bridge_get_physoutdev(skb);
95 if (physdev)
96 dev_hold(physdev);
97 }
98 #endif
99 }
100
101 /* Bump dev refs so they don't vanish while packet is out */
nf_queue_entry_get_refs(struct nf_queue_entry * entry)102 void nf_queue_entry_get_refs(struct nf_queue_entry *entry)
103 {
104 struct nf_hook_state *state = &entry->state;
105
106 if (state->in)
107 dev_hold(state->in);
108 if (state->out)
109 dev_hold(state->out);
110 if (state->sk)
111 sock_hold(state->sk);
112
113 nf_queue_entry_get_br_nf_refs(entry->skb);
114 }
115 EXPORT_SYMBOL_GPL(nf_queue_entry_get_refs);
116
nf_queue_nf_hook_drop(struct net * net)117 void nf_queue_nf_hook_drop(struct net *net)
118 {
119 const struct nf_queue_handler *qh;
120
121 rcu_read_lock();
122 qh = rcu_dereference(net->nf.queue_handler);
123 if (qh)
124 qh->nf_hook_drop(net);
125 rcu_read_unlock();
126 }
127 EXPORT_SYMBOL_GPL(nf_queue_nf_hook_drop);
128
nf_ip_saveroute(const struct sk_buff * skb,struct nf_queue_entry * entry)129 static void nf_ip_saveroute(const struct sk_buff *skb,
130 struct nf_queue_entry *entry)
131 {
132 struct ip_rt_info *rt_info = nf_queue_entry_reroute(entry);
133
134 if (entry->state.hook == NF_INET_LOCAL_OUT) {
135 const struct iphdr *iph = ip_hdr(skb);
136
137 rt_info->tos = iph->tos;
138 rt_info->daddr = iph->daddr;
139 rt_info->saddr = iph->saddr;
140 rt_info->mark = skb->mark;
141 }
142 }
143
nf_ip6_saveroute(const struct sk_buff * skb,struct nf_queue_entry * entry)144 static void nf_ip6_saveroute(const struct sk_buff *skb,
145 struct nf_queue_entry *entry)
146 {
147 struct ip6_rt_info *rt_info = nf_queue_entry_reroute(entry);
148
149 if (entry->state.hook == NF_INET_LOCAL_OUT) {
150 const struct ipv6hdr *iph = ipv6_hdr(skb);
151
152 rt_info->daddr = iph->daddr;
153 rt_info->saddr = iph->saddr;
154 rt_info->mark = skb->mark;
155 }
156 }
157
__nf_queue(struct sk_buff * skb,const struct nf_hook_state * state,unsigned int index,unsigned int queuenum)158 static int __nf_queue(struct sk_buff *skb, const struct nf_hook_state *state,
159 unsigned int index, unsigned int queuenum)
160 {
161 int status = -ENOENT;
162 struct nf_queue_entry *entry = NULL;
163 const struct nf_queue_handler *qh;
164 struct net *net = state->net;
165 unsigned int route_key_size;
166
167 /* QUEUE == DROP if no one is waiting, to be safe. */
168 qh = rcu_dereference(net->nf.queue_handler);
169 if (!qh) {
170 status = -ESRCH;
171 goto err;
172 }
173
174 switch (state->pf) {
175 case AF_INET:
176 route_key_size = sizeof(struct ip_rt_info);
177 break;
178 case AF_INET6:
179 route_key_size = sizeof(struct ip6_rt_info);
180 break;
181 default:
182 route_key_size = 0;
183 break;
184 }
185
186 entry = kmalloc(sizeof(*entry) + route_key_size, GFP_ATOMIC);
187 if (!entry) {
188 status = -ENOMEM;
189 goto err;
190 }
191
192 if (skb_dst(skb) && !skb_dst_force(skb)) {
193 status = -ENETDOWN;
194 goto err;
195 }
196
197 *entry = (struct nf_queue_entry) {
198 .skb = skb,
199 .state = *state,
200 .hook_index = index,
201 .size = sizeof(*entry) + route_key_size,
202 };
203
204 nf_queue_entry_get_refs(entry);
205
206 switch (entry->state.pf) {
207 case AF_INET:
208 nf_ip_saveroute(skb, entry);
209 break;
210 case AF_INET6:
211 nf_ip6_saveroute(skb, entry);
212 break;
213 }
214
215 status = qh->outfn(entry, queuenum);
216
217 if (status < 0) {
218 nf_queue_entry_release_refs(entry);
219 goto err;
220 }
221
222 return 0;
223
224 err:
225 kfree(entry);
226 return status;
227 }
228
229 /* Packets leaving via this function must come back through nf_reinject(). */
nf_queue(struct sk_buff * skb,struct nf_hook_state * state,unsigned int index,unsigned int verdict)230 int nf_queue(struct sk_buff *skb, struct nf_hook_state *state,
231 unsigned int index, unsigned int verdict)
232 {
233 int ret;
234
235 ret = __nf_queue(skb, state, index, verdict >> NF_VERDICT_QBITS);
236 if (ret < 0) {
237 if (ret == -ESRCH &&
238 (verdict & NF_VERDICT_FLAG_QUEUE_BYPASS))
239 return 1;
240 kfree_skb(skb);
241 }
242
243 return 0;
244 }
245 EXPORT_SYMBOL_GPL(nf_queue);
246
nf_iterate(struct sk_buff * skb,struct nf_hook_state * state,const struct nf_hook_entries * hooks,unsigned int * index)247 static unsigned int nf_iterate(struct sk_buff *skb,
248 struct nf_hook_state *state,
249 const struct nf_hook_entries *hooks,
250 unsigned int *index)
251 {
252 const struct nf_hook_entry *hook;
253 unsigned int verdict, i = *index;
254
255 while (i < hooks->num_hook_entries) {
256 hook = &hooks->hooks[i];
257 repeat:
258 verdict = nf_hook_entry_hookfn(hook, skb, state);
259 if (verdict != NF_ACCEPT) {
260 *index = i;
261 if (verdict != NF_REPEAT)
262 return verdict;
263 goto repeat;
264 }
265 i++;
266 }
267
268 *index = i;
269 return NF_ACCEPT;
270 }
271
nf_hook_entries_head(const struct net * net,u8 pf,u8 hooknum)272 static struct nf_hook_entries *nf_hook_entries_head(const struct net *net, u8 pf, u8 hooknum)
273 {
274 switch (pf) {
275 #ifdef CONFIG_NETFILTER_FAMILY_BRIDGE
276 case NFPROTO_BRIDGE:
277 return rcu_dereference(net->nf.hooks_bridge[hooknum]);
278 #endif
279 case NFPROTO_IPV4:
280 return rcu_dereference(net->nf.hooks_ipv4[hooknum]);
281 case NFPROTO_IPV6:
282 return rcu_dereference(net->nf.hooks_ipv6[hooknum]);
283 default:
284 WARN_ON_ONCE(1);
285 return NULL;
286 }
287
288 return NULL;
289 }
290
291 /* Caller must hold rcu read-side lock */
nf_reinject(struct nf_queue_entry * entry,unsigned int verdict)292 void nf_reinject(struct nf_queue_entry *entry, unsigned int verdict)
293 {
294 const struct nf_hook_entry *hook_entry;
295 const struct nf_hook_entries *hooks;
296 struct sk_buff *skb = entry->skb;
297 const struct net *net;
298 unsigned int i;
299 int err;
300 u8 pf;
301
302 net = entry->state.net;
303 pf = entry->state.pf;
304
305 hooks = nf_hook_entries_head(net, pf, entry->state.hook);
306
307 nf_queue_entry_release_refs(entry);
308
309 i = entry->hook_index;
310 if (WARN_ON_ONCE(!hooks || i >= hooks->num_hook_entries)) {
311 kfree_skb(skb);
312 kfree(entry);
313 return;
314 }
315
316 hook_entry = &hooks->hooks[i];
317
318 /* Continue traversal iff userspace said ok... */
319 if (verdict == NF_REPEAT)
320 verdict = nf_hook_entry_hookfn(hook_entry, skb, &entry->state);
321
322 if (verdict == NF_ACCEPT) {
323 if (nf_reroute(skb, entry) < 0)
324 verdict = NF_DROP;
325 }
326
327 if (verdict == NF_ACCEPT) {
328 next_hook:
329 ++i;
330 verdict = nf_iterate(skb, &entry->state, hooks, &i);
331 }
332
333 switch (verdict & NF_VERDICT_MASK) {
334 case NF_ACCEPT:
335 case NF_STOP:
336 local_bh_disable();
337 entry->state.okfn(entry->state.net, entry->state.sk, skb);
338 local_bh_enable();
339 break;
340 case NF_QUEUE:
341 err = nf_queue(skb, &entry->state, i, verdict);
342 if (err == 1)
343 goto next_hook;
344 break;
345 case NF_STOLEN:
346 break;
347 default:
348 kfree_skb(skb);
349 }
350
351 kfree(entry);
352 }
353 EXPORT_SYMBOL(nf_reinject);
354