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 static const struct nf_queue_handler __rcu *nf_queue_handler;
25
26 /*
27 * Hook for nfnetlink_queue to register its queue handler.
28 * We do this so that most of the NFQUEUE code can be modular.
29 *
30 * Once the queue is registered it must reinject all packets it
31 * receives, no matter what.
32 */
33
nf_register_queue_handler(const struct nf_queue_handler * qh)34 void nf_register_queue_handler(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(nf_queue_handler));
38 rcu_assign_pointer(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(void)43 void nf_unregister_queue_handler(void)
44 {
45 RCU_INIT_POINTER(nf_queue_handler, NULL);
46 }
47 EXPORT_SYMBOL(nf_unregister_queue_handler);
48
nf_queue_entry_release_refs(struct nf_queue_entry * entry)49 static void nf_queue_entry_release_refs(struct nf_queue_entry *entry)
50 {
51 struct nf_hook_state *state = &entry->state;
52
53 /* Release those devices we held, or Alexey will kill me. */
54 dev_put(state->in);
55 dev_put(state->out);
56 if (state->sk)
57 sock_put(state->sk);
58
59 #if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
60 dev_put(entry->physin);
61 dev_put(entry->physout);
62 #endif
63 }
64
nf_queue_entry_free(struct nf_queue_entry * entry)65 void nf_queue_entry_free(struct nf_queue_entry *entry)
66 {
67 nf_queue_entry_release_refs(entry);
68 kfree(entry);
69 }
70 EXPORT_SYMBOL_GPL(nf_queue_entry_free);
71
__nf_queue_entry_init_physdevs(struct nf_queue_entry * entry)72 static void __nf_queue_entry_init_physdevs(struct nf_queue_entry *entry)
73 {
74 #if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
75 const struct sk_buff *skb = entry->skb;
76 struct nf_bridge_info *nf_bridge;
77
78 nf_bridge = nf_bridge_info_get(skb);
79 if (nf_bridge) {
80 entry->physin = nf_bridge_get_physindev(skb);
81 entry->physout = nf_bridge_get_physoutdev(skb);
82 } else {
83 entry->physin = NULL;
84 entry->physout = NULL;
85 }
86 #endif
87 }
88
89 /* Bump dev refs so they don't vanish while packet is out */
nf_queue_entry_get_refs(struct nf_queue_entry * entry)90 void nf_queue_entry_get_refs(struct nf_queue_entry *entry)
91 {
92 struct nf_hook_state *state = &entry->state;
93
94 dev_hold(state->in);
95 dev_hold(state->out);
96 if (state->sk)
97 sock_hold(state->sk);
98
99 #if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
100 dev_hold(entry->physin);
101 dev_hold(entry->physout);
102 #endif
103 }
104 EXPORT_SYMBOL_GPL(nf_queue_entry_get_refs);
105
nf_queue_nf_hook_drop(struct net * net)106 void nf_queue_nf_hook_drop(struct net *net)
107 {
108 const struct nf_queue_handler *qh;
109
110 rcu_read_lock();
111 qh = rcu_dereference(nf_queue_handler);
112 if (qh)
113 qh->nf_hook_drop(net);
114 rcu_read_unlock();
115 }
116 EXPORT_SYMBOL_GPL(nf_queue_nf_hook_drop);
117
nf_ip_saveroute(const struct sk_buff * skb,struct nf_queue_entry * entry)118 static void nf_ip_saveroute(const struct sk_buff *skb,
119 struct nf_queue_entry *entry)
120 {
121 struct ip_rt_info *rt_info = nf_queue_entry_reroute(entry);
122
123 if (entry->state.hook == NF_INET_LOCAL_OUT) {
124 const struct iphdr *iph = ip_hdr(skb);
125
126 rt_info->tos = iph->tos;
127 rt_info->daddr = iph->daddr;
128 rt_info->saddr = iph->saddr;
129 rt_info->mark = skb->mark;
130 }
131 }
132
nf_ip6_saveroute(const struct sk_buff * skb,struct nf_queue_entry * entry)133 static void nf_ip6_saveroute(const struct sk_buff *skb,
134 struct nf_queue_entry *entry)
135 {
136 struct ip6_rt_info *rt_info = nf_queue_entry_reroute(entry);
137
138 if (entry->state.hook == NF_INET_LOCAL_OUT) {
139 const struct ipv6hdr *iph = ipv6_hdr(skb);
140
141 rt_info->daddr = iph->daddr;
142 rt_info->saddr = iph->saddr;
143 rt_info->mark = skb->mark;
144 }
145 }
146
__nf_queue(struct sk_buff * skb,const struct nf_hook_state * state,unsigned int index,unsigned int queuenum)147 static int __nf_queue(struct sk_buff *skb, const struct nf_hook_state *state,
148 unsigned int index, unsigned int queuenum)
149 {
150 struct nf_queue_entry *entry = NULL;
151 const struct nf_queue_handler *qh;
152 unsigned int route_key_size;
153 int status;
154
155 /* QUEUE == DROP if no one is waiting, to be safe. */
156 qh = rcu_dereference(nf_queue_handler);
157 if (!qh)
158 return -ESRCH;
159
160 switch (state->pf) {
161 case AF_INET:
162 route_key_size = sizeof(struct ip_rt_info);
163 break;
164 case AF_INET6:
165 route_key_size = sizeof(struct ip6_rt_info);
166 break;
167 default:
168 route_key_size = 0;
169 break;
170 }
171
172 entry = kmalloc(sizeof(*entry) + route_key_size, GFP_ATOMIC);
173 if (!entry)
174 return -ENOMEM;
175
176 if (skb_dst(skb) && !skb_dst_force(skb)) {
177 kfree(entry);
178 return -ENETDOWN;
179 }
180
181 *entry = (struct nf_queue_entry) {
182 .skb = skb,
183 .state = *state,
184 .hook_index = index,
185 .size = sizeof(*entry) + route_key_size,
186 };
187
188 __nf_queue_entry_init_physdevs(entry);
189
190 nf_queue_entry_get_refs(entry);
191
192 switch (entry->state.pf) {
193 case AF_INET:
194 nf_ip_saveroute(skb, entry);
195 break;
196 case AF_INET6:
197 nf_ip6_saveroute(skb, entry);
198 break;
199 }
200
201 status = qh->outfn(entry, queuenum);
202 if (status < 0) {
203 nf_queue_entry_free(entry);
204 return status;
205 }
206
207 return 0;
208 }
209
210 /* 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)211 int nf_queue(struct sk_buff *skb, struct nf_hook_state *state,
212 unsigned int index, unsigned int verdict)
213 {
214 int ret;
215
216 ret = __nf_queue(skb, state, index, verdict >> NF_VERDICT_QBITS);
217 if (ret < 0) {
218 if (ret == -ESRCH &&
219 (verdict & NF_VERDICT_FLAG_QUEUE_BYPASS))
220 return 1;
221 kfree_skb(skb);
222 }
223
224 return 0;
225 }
226 EXPORT_SYMBOL_GPL(nf_queue);
227
nf_iterate(struct sk_buff * skb,struct nf_hook_state * state,const struct nf_hook_entries * hooks,unsigned int * index)228 static unsigned int nf_iterate(struct sk_buff *skb,
229 struct nf_hook_state *state,
230 const struct nf_hook_entries *hooks,
231 unsigned int *index)
232 {
233 const struct nf_hook_entry *hook;
234 unsigned int verdict, i = *index;
235
236 while (i < hooks->num_hook_entries) {
237 hook = &hooks->hooks[i];
238 repeat:
239 verdict = nf_hook_entry_hookfn(hook, skb, state);
240 if (verdict != NF_ACCEPT) {
241 *index = i;
242 if (verdict != NF_REPEAT)
243 return verdict;
244 goto repeat;
245 }
246 i++;
247 }
248
249 *index = i;
250 return NF_ACCEPT;
251 }
252
nf_hook_entries_head(const struct net * net,u8 pf,u8 hooknum)253 static struct nf_hook_entries *nf_hook_entries_head(const struct net *net, u8 pf, u8 hooknum)
254 {
255 switch (pf) {
256 #ifdef CONFIG_NETFILTER_FAMILY_BRIDGE
257 case NFPROTO_BRIDGE:
258 return rcu_dereference(net->nf.hooks_bridge[hooknum]);
259 #endif
260 case NFPROTO_IPV4:
261 return rcu_dereference(net->nf.hooks_ipv4[hooknum]);
262 case NFPROTO_IPV6:
263 return rcu_dereference(net->nf.hooks_ipv6[hooknum]);
264 default:
265 WARN_ON_ONCE(1);
266 return NULL;
267 }
268
269 return NULL;
270 }
271
272 /* Caller must hold rcu read-side lock */
nf_reinject(struct nf_queue_entry * entry,unsigned int verdict)273 void nf_reinject(struct nf_queue_entry *entry, unsigned int verdict)
274 {
275 const struct nf_hook_entry *hook_entry;
276 const struct nf_hook_entries *hooks;
277 struct sk_buff *skb = entry->skb;
278 const struct net *net;
279 unsigned int i;
280 int err;
281 u8 pf;
282
283 net = entry->state.net;
284 pf = entry->state.pf;
285
286 hooks = nf_hook_entries_head(net, pf, entry->state.hook);
287
288 i = entry->hook_index;
289 if (WARN_ON_ONCE(!hooks || i >= hooks->num_hook_entries)) {
290 kfree_skb(skb);
291 nf_queue_entry_free(entry);
292 return;
293 }
294
295 hook_entry = &hooks->hooks[i];
296
297 /* Continue traversal iff userspace said ok... */
298 if (verdict == NF_REPEAT)
299 verdict = nf_hook_entry_hookfn(hook_entry, skb, &entry->state);
300
301 if (verdict == NF_ACCEPT) {
302 if (nf_reroute(skb, entry) < 0)
303 verdict = NF_DROP;
304 }
305
306 if (verdict == NF_ACCEPT) {
307 next_hook:
308 ++i;
309 verdict = nf_iterate(skb, &entry->state, hooks, &i);
310 }
311
312 switch (verdict & NF_VERDICT_MASK) {
313 case NF_ACCEPT:
314 case NF_STOP:
315 local_bh_disable();
316 entry->state.okfn(entry->state.net, entry->state.sk, skb);
317 local_bh_enable();
318 break;
319 case NF_QUEUE:
320 err = nf_queue(skb, &entry->state, i, verdict);
321 if (err == 1)
322 goto next_hook;
323 break;
324 case NF_STOLEN:
325 break;
326 default:
327 kfree_skb(skb);
328 }
329
330 nf_queue_entry_free(entry);
331 }
332 EXPORT_SYMBOL(nf_reinject);
333