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
24static 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
34void 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}
40EXPORT_SYMBOL(nf_register_queue_handler);
41
42/* The caller must flush their queue before this */
43void nf_unregister_queue_handler(void)
44{
45 RCU_INIT_POINTER(nf_queue_handler, NULL);
46}
47EXPORT_SYMBOL(nf_unregister_queue_handler);
48
49static void nf_queue_sock_put(struct sock *sk)
50{
51#ifdef CONFIG_INET
52 sock_gen_put(sk);
53#else
54 sock_put(sk);
55#endif
56}
57
58static void nf_queue_entry_release_refs(struct nf_queue_entry *entry)
59{
60 struct nf_hook_state *state = &entry->state;
61
62 /* Release those devices we held, or Alexey will kill me. */
63 dev_put(dev: state->in);
64 dev_put(dev: state->out);
65 if (state->sk)
66 nf_queue_sock_put(sk: state->sk);
67
68#if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
69 dev_put(entry->physin);
70 dev_put(entry->physout);
71#endif
72}
73
74void nf_queue_entry_free(struct nf_queue_entry *entry)
75{
76 nf_queue_entry_release_refs(entry);
77 kfree(objp: entry);
78}
79EXPORT_SYMBOL_GPL(nf_queue_entry_free);
80
81static void __nf_queue_entry_init_physdevs(struct nf_queue_entry *entry)
82{
83#if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
84 const struct sk_buff *skb = entry->skb;
85
86 if (nf_bridge_info_exists(skb)) {
87 entry->physin = nf_bridge_get_physindev(skb, entry->state.net);
88 entry->physout = nf_bridge_get_physoutdev(skb);
89 } else {
90 entry->physin = NULL;
91 entry->physout = NULL;
92 }
93#endif
94}
95
96/* Bump dev refs so they don't vanish while packet is out */
97bool nf_queue_entry_get_refs(struct nf_queue_entry *entry)
98{
99 struct nf_hook_state *state = &entry->state;
100
101 if (state->sk && !refcount_inc_not_zero(r: &state->sk->sk_refcnt))
102 return false;
103
104 dev_hold(dev: state->in);
105 dev_hold(dev: state->out);
106
107#if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
108 dev_hold(entry->physin);
109 dev_hold(entry->physout);
110#endif
111 return true;
112}
113EXPORT_SYMBOL_GPL(nf_queue_entry_get_refs);
114
115void nf_queue_nf_hook_drop(struct net *net)
116{
117 const struct nf_queue_handler *qh;
118
119 rcu_read_lock();
120 qh = rcu_dereference(nf_queue_handler);
121 if (qh)
122 qh->nf_hook_drop(net);
123 rcu_read_unlock();
124}
125EXPORT_SYMBOL_GPL(nf_queue_nf_hook_drop);
126
127static void nf_ip_saveroute(const struct sk_buff *skb,
128 struct nf_queue_entry *entry)
129{
130 struct ip_rt_info *rt_info = nf_queue_entry_reroute(entry);
131
132 if (entry->state.hook == NF_INET_LOCAL_OUT) {
133 const struct iphdr *iph = ip_hdr(skb);
134
135 rt_info->tos = iph->tos;
136 rt_info->daddr = iph->daddr;
137 rt_info->saddr = iph->saddr;
138 rt_info->mark = skb->mark;
139 }
140}
141
142static void nf_ip6_saveroute(const struct sk_buff *skb,
143 struct nf_queue_entry *entry)
144{
145 struct ip6_rt_info *rt_info = nf_queue_entry_reroute(entry);
146
147 if (entry->state.hook == NF_INET_LOCAL_OUT) {
148 const struct ipv6hdr *iph = ipv6_hdr(skb);
149
150 rt_info->daddr = iph->daddr;
151 rt_info->saddr = iph->saddr;
152 rt_info->mark = skb->mark;
153 }
154}
155
156static int __nf_queue(struct sk_buff *skb, const struct nf_hook_state *state,
157 unsigned int index, unsigned int queuenum)
158{
159 struct nf_queue_entry *entry = NULL;
160 const struct nf_queue_handler *qh;
161 unsigned int route_key_size;
162 int status;
163
164 /* QUEUE == DROP if no one is waiting, to be safe. */
165 qh = rcu_dereference(nf_queue_handler);
166 if (!qh)
167 return -ESRCH;
168
169 switch (state->pf) {
170 case AF_INET:
171 route_key_size = sizeof(struct ip_rt_info);
172 break;
173 case AF_INET6:
174 route_key_size = sizeof(struct ip6_rt_info);
175 break;
176 default:
177 route_key_size = 0;
178 break;
179 }
180
181 if (skb_sk_is_prefetched(skb)) {
182 struct sock *sk = skb->sk;
183
184 if (!sk_is_refcounted(sk)) {
185 if (!refcount_inc_not_zero(r: &sk->sk_refcnt))
186 return -ENOTCONN;
187
188 /* drop refcount on skb_orphan */
189 skb->destructor = sock_edemux;
190 }
191 }
192
193 entry = kmalloc(sizeof(*entry) + route_key_size, GFP_ATOMIC);
194 if (!entry)
195 return -ENOMEM;
196
197 if (skb_dst(skb) && !skb_dst_force(skb)) {
198 kfree(objp: entry);
199 return -ENETDOWN;
200 }
201
202 *entry = (struct nf_queue_entry) {
203 .skb = skb,
204 .state = *state,
205 .hook_index = index,
206 .size = sizeof(*entry) + route_key_size,
207 };
208
209 __nf_queue_entry_init_physdevs(entry);
210
211 if (!nf_queue_entry_get_refs(entry)) {
212 kfree(objp: entry);
213 return -ENOTCONN;
214 }
215
216 switch (entry->state.pf) {
217 case AF_INET:
218 nf_ip_saveroute(skb, entry);
219 break;
220 case AF_INET6:
221 nf_ip6_saveroute(skb, entry);
222 break;
223 }
224
225 status = qh->outfn(entry, queuenum);
226 if (status < 0) {
227 nf_queue_entry_free(entry);
228 return status;
229 }
230
231 return 0;
232}
233
234/* Packets leaving via this function must come back through nf_reinject(). */
235int nf_queue(struct sk_buff *skb, struct nf_hook_state *state,
236 unsigned int index, unsigned int verdict)
237{
238 int ret;
239
240 ret = __nf_queue(skb, state, index, queuenum: verdict >> NF_VERDICT_QBITS);
241 if (ret < 0) {
242 if (ret == -ESRCH &&
243 (verdict & NF_VERDICT_FLAG_QUEUE_BYPASS))
244 return 1;
245 kfree_skb(skb);
246 }
247
248 return 0;
249}
250EXPORT_SYMBOL_GPL(nf_queue);
251