Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
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linux
1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * Rusty Russell (C)2000 -- This code is GPL.
4 * Patrick McHardy (c) 2006-2012
5 */
6
7#include <linux/kernel.h>
8#include <linux/slab.h>
9#include <linux/init.h>
10#include <linux/module.h>
11#include <linux/proc_fs.h>
12#include <linux/skbuff.h>
13#include <linux/netfilter.h>
14#include <linux/netfilter_ipv4.h>
15#include <linux/netfilter_ipv6.h>
16#include <linux/netfilter_bridge.h>
17#include <linux/seq_file.h>
18#include <linux/rcupdate.h>
19#include <net/protocol.h>
20#include <net/netfilter/nf_queue.h>
21#include <net/dst.h>
22
23#include "nf_internals.h"
24
25static const struct nf_queue_handler __rcu *nf_queue_handler;
26
27/*
28 * Hook for nfnetlink_queue to register its queue handler.
29 * We do this so that most of the NFQUEUE code can be modular.
30 *
31 * Once the queue is registered it must reinject all packets it
32 * receives, no matter what.
33 */
34
35void nf_register_queue_handler(const struct nf_queue_handler *qh)
36{
37 /* should never happen, we only have one queueing backend in kernel */
38 WARN_ON(rcu_access_pointer(nf_queue_handler));
39 rcu_assign_pointer(nf_queue_handler, qh);
40}
41EXPORT_SYMBOL(nf_register_queue_handler);
42
43/* The caller must flush their queue before this */
44void nf_unregister_queue_handler(void)
45{
46 RCU_INIT_POINTER(nf_queue_handler, NULL);
47}
48EXPORT_SYMBOL(nf_unregister_queue_handler);
49
50static void nf_queue_sock_put(struct sock *sk)
51{
52#ifdef CONFIG_INET
53 sock_gen_put(sk);
54#else
55 sock_put(sk);
56#endif
57}
58
59static void nf_queue_entry_release_refs(struct nf_queue_entry *entry)
60{
61 struct nf_hook_state *state = &entry->state;
62
63 /* Release those devices we held, or Alexey will kill me. */
64 dev_put(state->in);
65 dev_put(state->out);
66 if (state->sk)
67 nf_queue_sock_put(state->sk);
68
69#if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
70 dev_put(entry->physin);
71 dev_put(entry->physout);
72#endif
73}
74
75void nf_queue_entry_free(struct nf_queue_entry *entry)
76{
77 nf_queue_entry_release_refs(entry);
78 kfree(entry);
79}
80EXPORT_SYMBOL_GPL(nf_queue_entry_free);
81
82static void __nf_queue_entry_init_physdevs(struct nf_queue_entry *entry)
83{
84#if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
85 const struct sk_buff *skb = entry->skb;
86
87 if (nf_bridge_info_exists(skb)) {
88 entry->physin = nf_bridge_get_physindev(skb, entry->state.net);
89 entry->physout = nf_bridge_get_physoutdev(skb);
90 } else {
91 entry->physin = NULL;
92 entry->physout = NULL;
93 }
94#endif
95}
96
97/* Bump dev refs so they don't vanish while packet is out */
98bool nf_queue_entry_get_refs(struct nf_queue_entry *entry)
99{
100 struct nf_hook_state *state = &entry->state;
101
102 if (state->sk && !refcount_inc_not_zero(&state->sk->sk_refcnt))
103 return false;
104
105 dev_hold(state->in);
106 dev_hold(state->out);
107
108#if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
109 dev_hold(entry->physin);
110 dev_hold(entry->physout);
111#endif
112 return true;
113}
114EXPORT_SYMBOL_GPL(nf_queue_entry_get_refs);
115
116void nf_queue_nf_hook_drop(struct net *net)
117{
118 const struct nf_queue_handler *qh;
119
120 rcu_read_lock();
121 qh = rcu_dereference(nf_queue_handler);
122 if (qh)
123 qh->nf_hook_drop(net);
124 rcu_read_unlock();
125}
126EXPORT_SYMBOL_GPL(nf_queue_nf_hook_drop);
127
128static void nf_ip_saveroute(const struct sk_buff *skb,
129 struct nf_queue_entry *entry)
130{
131 struct ip_rt_info *rt_info = nf_queue_entry_reroute(entry);
132
133 if (entry->state.hook == NF_INET_LOCAL_OUT) {
134 const struct iphdr *iph = ip_hdr(skb);
135
136 rt_info->tos = iph->tos;
137 rt_info->daddr = iph->daddr;
138 rt_info->saddr = iph->saddr;
139 rt_info->mark = skb->mark;
140 }
141}
142
143static void nf_ip6_saveroute(const struct sk_buff *skb,
144 struct nf_queue_entry *entry)
145{
146 struct ip6_rt_info *rt_info = nf_queue_entry_reroute(entry);
147
148 if (entry->state.hook == NF_INET_LOCAL_OUT) {
149 const struct ipv6hdr *iph = ipv6_hdr(skb);
150
151 rt_info->daddr = iph->daddr;
152 rt_info->saddr = iph->saddr;
153 rt_info->mark = skb->mark;
154 }
155}
156
157static int __nf_queue(struct sk_buff *skb, const struct nf_hook_state *state,
158 unsigned int index, unsigned int queuenum)
159{
160 struct nf_queue_entry *entry = NULL;
161 const struct nf_queue_handler *qh;
162 unsigned int route_key_size;
163 int status;
164
165 /* QUEUE == DROP if no one is waiting, to be safe. */
166 qh = rcu_dereference(nf_queue_handler);
167 if (!qh)
168 return -ESRCH;
169
170 switch (state->pf) {
171 case AF_INET:
172 route_key_size = sizeof(struct ip_rt_info);
173 break;
174 case AF_INET6:
175 route_key_size = sizeof(struct ip6_rt_info);
176 break;
177 default:
178 route_key_size = 0;
179 break;
180 }
181
182 if (skb_sk_is_prefetched(skb)) {
183 struct sock *sk = skb->sk;
184
185 if (!sk_is_refcounted(sk)) {
186 if (!refcount_inc_not_zero(&sk->sk_refcnt))
187 return -ENOTCONN;
188
189 /* drop refcount on skb_orphan */
190 skb->destructor = sock_edemux;
191 }
192 }
193
194 entry = kmalloc(sizeof(*entry) + route_key_size, GFP_ATOMIC);
195 if (!entry)
196 return -ENOMEM;
197
198 if (skb_dst(skb) && !skb_dst_force(skb)) {
199 kfree(entry);
200 return -ENETDOWN;
201 }
202
203 *entry = (struct nf_queue_entry) {
204 .skb = skb,
205 .state = *state,
206 .hook_index = index,
207 .size = sizeof(*entry) + route_key_size,
208 };
209
210 __nf_queue_entry_init_physdevs(entry);
211
212 if (!nf_queue_entry_get_refs(entry)) {
213 kfree(entry);
214 return -ENOTCONN;
215 }
216
217 switch (entry->state.pf) {
218 case AF_INET:
219 nf_ip_saveroute(skb, entry);
220 break;
221 case AF_INET6:
222 nf_ip6_saveroute(skb, entry);
223 break;
224 }
225
226 status = qh->outfn(entry, queuenum);
227 if (status < 0) {
228 nf_queue_entry_free(entry);
229 return status;
230 }
231
232 return 0;
233}
234
235/* Packets leaving via this function must come back through nf_reinject(). */
236int nf_queue(struct sk_buff *skb, struct nf_hook_state *state,
237 unsigned int index, unsigned int verdict)
238{
239 int ret;
240
241 ret = __nf_queue(skb, state, index, verdict >> NF_VERDICT_QBITS);
242 if (ret < 0) {
243 if (ret == -ESRCH &&
244 (verdict & NF_VERDICT_FLAG_QUEUE_BYPASS))
245 return 1;
246 kfree_skb(skb);
247 }
248
249 return 0;
250}
251EXPORT_SYMBOL_GPL(nf_queue);