1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
|
/*
* Rusty Russell (C)2000 -- This code is GPL.
* Patrick McHardy (c) 2006-2012
*/
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/proc_fs.h>
#include <linux/skbuff.h>
#include <linux/netfilter.h>
#include <linux/seq_file.h>
#include <linux/rcupdate.h>
#include <net/protocol.h>
#include <net/netfilter/nf_queue.h>
#include <net/dst.h>
#include "nf_internals.h"
/*
* Hook for nfnetlink_queue to register its queue handler.
* We do this so that most of the NFQUEUE code can be modular.
*
* Once the queue is registered it must reinject all packets it
* receives, no matter what.
*/
static const struct nf_queue_handler __rcu *queue_handler __read_mostly;
/* return EBUSY when somebody else is registered, return EEXIST if the
* same handler is registered, return 0 in case of success. */
void nf_register_queue_handler(const struct nf_queue_handler *qh)
{
/* should never happen, we only have one queueing backend in kernel */
WARN_ON(rcu_access_pointer(queue_handler));
rcu_assign_pointer(queue_handler, qh);
}
EXPORT_SYMBOL(nf_register_queue_handler);
/* The caller must flush their queue before this */
void nf_unregister_queue_handler(void)
{
RCU_INIT_POINTER(queue_handler, NULL);
synchronize_rcu();
}
EXPORT_SYMBOL(nf_unregister_queue_handler);
void nf_queue_entry_release_refs(struct nf_queue_entry *entry)
{
/* Release those devices we held, or Alexey will kill me. */
if (entry->indev)
dev_put(entry->indev);
if (entry->outdev)
dev_put(entry->outdev);
#if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
if (entry->skb->nf_bridge) {
struct nf_bridge_info *nf_bridge = entry->skb->nf_bridge;
if (nf_bridge->physindev)
dev_put(nf_bridge->physindev);
if (nf_bridge->physoutdev)
dev_put(nf_bridge->physoutdev);
}
#endif
/* Drop reference to owner of hook which queued us. */
module_put(entry->elem->owner);
}
EXPORT_SYMBOL_GPL(nf_queue_entry_release_refs);
/* Bump dev refs so they don't vanish while packet is out */
bool nf_queue_entry_get_refs(struct nf_queue_entry *entry)
{
if (!try_module_get(entry->elem->owner))
return false;
if (entry->indev)
dev_hold(entry->indev);
if (entry->outdev)
dev_hold(entry->outdev);
#if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
if (entry->skb->nf_bridge) {
struct nf_bridge_info *nf_bridge = entry->skb->nf_bridge;
struct net_device *physdev;
physdev = nf_bridge->physindev;
if (physdev)
dev_hold(physdev);
physdev = nf_bridge->physoutdev;
if (physdev)
dev_hold(physdev);
}
#endif
return true;
}
EXPORT_SYMBOL_GPL(nf_queue_entry_get_refs);
/*
* Any packet that leaves via this function must come back
* through nf_reinject().
*/
int nf_queue(struct sk_buff *skb,
struct nf_hook_ops *elem,
u_int8_t pf, unsigned int hook,
struct net_device *indev,
struct net_device *outdev,
int (*okfn)(struct sk_buff *),
unsigned int queuenum)
{
int status = -ENOENT;
struct nf_queue_entry *entry = NULL;
const struct nf_afinfo *afinfo;
const struct nf_queue_handler *qh;
/* QUEUE == DROP if no one is waiting, to be safe. */
rcu_read_lock();
qh = rcu_dereference(queue_handler);
if (!qh) {
status = -ESRCH;
goto err_unlock;
}
afinfo = nf_get_afinfo(pf);
if (!afinfo)
goto err_unlock;
entry = kmalloc(sizeof(*entry) + afinfo->route_key_size, GFP_ATOMIC);
if (!entry) {
status = -ENOMEM;
goto err_unlock;
}
*entry = (struct nf_queue_entry) {
.skb = skb,
.elem = elem,
.pf = pf,
.hook = hook,
.indev = indev,
.outdev = outdev,
.okfn = okfn,
.size = sizeof(*entry) + afinfo->route_key_size,
};
if (!nf_queue_entry_get_refs(entry)) {
status = -ECANCELED;
goto err_unlock;
}
skb_dst_force(skb);
afinfo->saveroute(skb, entry);
status = qh->outfn(entry, queuenum);
rcu_read_unlock();
if (status < 0) {
nf_queue_entry_release_refs(entry);
goto err;
}
return 0;
err_unlock:
rcu_read_unlock();
err:
kfree(entry);
return status;
}
void nf_reinject(struct nf_queue_entry *entry, unsigned int verdict)
{
struct sk_buff *skb = entry->skb;
struct nf_hook_ops *elem = entry->elem;
const struct nf_afinfo *afinfo;
int err;
rcu_read_lock();
nf_queue_entry_release_refs(entry);
/* Continue traversal iff userspace said ok... */
if (verdict == NF_REPEAT) {
elem = list_entry(elem->list.prev, struct nf_hook_ops, list);
verdict = NF_ACCEPT;
}
if (verdict == NF_ACCEPT) {
afinfo = nf_get_afinfo(entry->pf);
if (!afinfo || afinfo->reroute(skb, entry) < 0)
verdict = NF_DROP;
}
if (verdict == NF_ACCEPT) {
next_hook:
verdict = nf_iterate(&nf_hooks[entry->pf][entry->hook],
skb, entry->hook,
entry->indev, entry->outdev, &elem,
entry->okfn, INT_MIN);
}
switch (verdict & NF_VERDICT_MASK) {
case NF_ACCEPT:
case NF_STOP:
local_bh_disable();
entry->okfn(skb);
local_bh_enable();
break;
case NF_QUEUE:
err = nf_queue(skb, elem, entry->pf, entry->hook,
entry->indev, entry->outdev, entry->okfn,
verdict >> NF_VERDICT_QBITS);
if (err < 0) {
if (err == -ECANCELED)
goto next_hook;
if (err == -ESRCH &&
(verdict & NF_VERDICT_FLAG_QUEUE_BYPASS))
goto next_hook;
kfree_skb(skb);
}
break;
case NF_STOLEN:
break;
default:
kfree_skb(skb);
}
rcu_read_unlock();
kfree(entry);
}
EXPORT_SYMBOL(nf_reinject);
|
