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 static const struct nf_queue_handler __rcu *queue_handler __read_mostly;
30
31 /* return EBUSY when somebody else is registered, return EEXIST if the
32 * same handler is registered, return 0 in case of success. */
nf_register_queue_handler(const struct nf_queue_handler * qh)33 void nf_register_queue_handler(const struct nf_queue_handler *qh)
34 {
35 /* should never happen, we only have one queueing backend in kernel */
36 WARN_ON(rcu_access_pointer(queue_handler));
37 rcu_assign_pointer(queue_handler, qh);
38 }
39 EXPORT_SYMBOL(nf_register_queue_handler);
40
41 /* The caller must flush their queue before this */
nf_unregister_queue_handler(void)42 void nf_unregister_queue_handler(void)
43 {
44 RCU_INIT_POINTER(queue_handler, NULL);
45 synchronize_rcu();
46 }
47 EXPORT_SYMBOL(nf_unregister_queue_handler);
48
nf_queue_entry_release_refs(struct nf_queue_entry * entry)49 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 if (state->in)
55 dev_put(state->in);
56 if (state->out)
57 dev_put(state->out);
58 if (state->sk)
59 sock_put(state->sk);
60 #if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
61 if (entry->skb->nf_bridge) {
62 struct net_device *physdev;
63
64 physdev = nf_bridge_get_physindev(entry->skb);
65 if (physdev)
66 dev_put(physdev);
67 physdev = nf_bridge_get_physoutdev(entry->skb);
68 if (physdev)
69 dev_put(physdev);
70 }
71 #endif
72 /* Drop reference to owner of hook which queued us. */
73 module_put(entry->elem->owner);
74 }
75 EXPORT_SYMBOL_GPL(nf_queue_entry_release_refs);
76
77 /* Bump dev refs so they don't vanish while packet is out */
nf_queue_entry_get_refs(struct nf_queue_entry * entry)78 bool nf_queue_entry_get_refs(struct nf_queue_entry *entry)
79 {
80 struct nf_hook_state *state = &entry->state;
81
82 if (!try_module_get(entry->elem->owner))
83 return false;
84
85 if (state->in)
86 dev_hold(state->in);
87 if (state->out)
88 dev_hold(state->out);
89 if (state->sk)
90 sock_hold(state->sk);
91 #if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
92 if (entry->skb->nf_bridge) {
93 struct net_device *physdev;
94
95 physdev = nf_bridge_get_physindev(entry->skb);
96 if (physdev)
97 dev_hold(physdev);
98 physdev = nf_bridge_get_physoutdev(entry->skb);
99 if (physdev)
100 dev_hold(physdev);
101 }
102 #endif
103
104 return true;
105 }
106 EXPORT_SYMBOL_GPL(nf_queue_entry_get_refs);
107
nf_queue_nf_hook_drop(struct nf_hook_ops * ops)108 void nf_queue_nf_hook_drop(struct nf_hook_ops *ops)
109 {
110 const struct nf_queue_handler *qh;
111 struct net *net;
112
113 rtnl_lock();
114 rcu_read_lock();
115 qh = rcu_dereference(queue_handler);
116 if (qh) {
117 for_each_net(net) {
118 qh->nf_hook_drop(net, ops);
119 }
120 }
121 rcu_read_unlock();
122 rtnl_unlock();
123 }
124
125 /*
126 * Any packet that leaves via this function must come back
127 * through nf_reinject().
128 */
nf_queue(struct sk_buff * skb,struct nf_hook_ops * elem,struct nf_hook_state * state,unsigned int queuenum)129 int nf_queue(struct sk_buff *skb,
130 struct nf_hook_ops *elem,
131 struct nf_hook_state *state,
132 unsigned int queuenum)
133 {
134 int status = -ENOENT;
135 struct nf_queue_entry *entry = NULL;
136 const struct nf_afinfo *afinfo;
137 const struct nf_queue_handler *qh;
138
139 /* QUEUE == DROP if no one is waiting, to be safe. */
140 rcu_read_lock();
141
142 qh = rcu_dereference(queue_handler);
143 if (!qh) {
144 status = -ESRCH;
145 goto err_unlock;
146 }
147
148 afinfo = nf_get_afinfo(state->pf);
149 if (!afinfo)
150 goto err_unlock;
151
152 entry = kmalloc(sizeof(*entry) + afinfo->route_key_size, GFP_ATOMIC);
153 if (!entry) {
154 status = -ENOMEM;
155 goto err_unlock;
156 }
157
158 *entry = (struct nf_queue_entry) {
159 .skb = skb,
160 .elem = elem,
161 .state = *state,
162 .size = sizeof(*entry) + afinfo->route_key_size,
163 };
164
165 if (!nf_queue_entry_get_refs(entry)) {
166 status = -ECANCELED;
167 goto err_unlock;
168 }
169 skb_dst_force(skb);
170 afinfo->saveroute(skb, entry);
171 status = qh->outfn(entry, queuenum);
172
173 rcu_read_unlock();
174
175 if (status < 0) {
176 nf_queue_entry_release_refs(entry);
177 goto err;
178 }
179
180 return 0;
181
182 err_unlock:
183 rcu_read_unlock();
184 err:
185 kfree(entry);
186 return status;
187 }
188
nf_reinject(struct nf_queue_entry * entry,unsigned int verdict)189 void nf_reinject(struct nf_queue_entry *entry, unsigned int verdict)
190 {
191 struct sk_buff *skb = entry->skb;
192 struct nf_hook_ops *elem = entry->elem;
193 const struct nf_afinfo *afinfo;
194 int err;
195
196 rcu_read_lock();
197
198 nf_queue_entry_release_refs(entry);
199
200 /* Continue traversal iff userspace said ok... */
201 if (verdict == NF_REPEAT) {
202 elem = list_entry(elem->list.prev, struct nf_hook_ops, list);
203 verdict = NF_ACCEPT;
204 }
205
206 if (verdict == NF_ACCEPT) {
207 afinfo = nf_get_afinfo(entry->state.pf);
208 if (!afinfo || afinfo->reroute(skb, entry) < 0)
209 verdict = NF_DROP;
210 }
211
212 entry->state.thresh = INT_MIN;
213
214 if (verdict == NF_ACCEPT) {
215 next_hook:
216 verdict = nf_iterate(&nf_hooks[entry->state.pf][entry->state.hook],
217 skb, &entry->state, &elem);
218 }
219
220 switch (verdict & NF_VERDICT_MASK) {
221 case NF_ACCEPT:
222 case NF_STOP:
223 local_bh_disable();
224 entry->state.okfn(entry->state.sk, skb);
225 local_bh_enable();
226 break;
227 case NF_QUEUE:
228 err = nf_queue(skb, elem, &entry->state,
229 verdict >> NF_VERDICT_QBITS);
230 if (err < 0) {
231 if (err == -ECANCELED)
232 goto next_hook;
233 if (err == -ESRCH &&
234 (verdict & NF_VERDICT_FLAG_QUEUE_BYPASS))
235 goto next_hook;
236 kfree_skb(skb);
237 }
238 break;
239 case NF_STOLEN:
240 break;
241 default:
242 kfree_skb(skb);
243 }
244 rcu_read_unlock();
245 kfree(entry);
246 }
247 EXPORT_SYMBOL(nf_reinject);
248