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be6b635c AB |
1 | /* |
2 | * Copyright (c) 2011 Patrick McHardy <kaber@trash.net> | |
3 | * | |
4 | * This program is free software; you can redistribute it and/or modify | |
5 | * it under the terms of the GNU General Public License version 2 as | |
6 | * published by the Free Software Foundation. | |
7 | * | |
8 | * Based on Rusty Russell's IPv6 MASQUERADE target. Development of IPv6 | |
9 | * NAT funded by Astaro. | |
10 | */ | |
11 | ||
12 | #include <linux/kernel.h> | |
13 | #include <linux/module.h> | |
14 | #include <linux/atomic.h> | |
15 | #include <linux/netdevice.h> | |
16 | #include <linux/ipv6.h> | |
17 | #include <linux/netfilter.h> | |
18 | #include <linux/netfilter_ipv6.h> | |
19 | #include <net/netfilter/nf_nat.h> | |
20 | #include <net/addrconf.h> | |
21 | #include <net/ipv6.h> | |
22 | #include <net/netfilter/ipv6/nf_nat_masquerade.h> | |
23 | ||
d93c6258 FW |
24 | #define MAX_WORK_COUNT 16 |
25 | ||
26 | static atomic_t v6_worker_count; | |
27 | ||
be6b635c AB |
28 | unsigned int |
29 | nf_nat_masquerade_ipv6(struct sk_buff *skb, const struct nf_nat_range *range, | |
30 | const struct net_device *out) | |
31 | { | |
32 | enum ip_conntrack_info ctinfo; | |
33 | struct in6_addr src; | |
34 | struct nf_conn *ct; | |
35 | struct nf_nat_range newrange; | |
36 | ||
37 | ct = nf_ct_get(skb, &ctinfo); | |
38 | NF_CT_ASSERT(ct && (ctinfo == IP_CT_NEW || ctinfo == IP_CT_RELATED || | |
39 | ctinfo == IP_CT_RELATED_REPLY)); | |
40 | ||
0a031ac5 | 41 | if (ipv6_dev_get_saddr(nf_ct_net(ct), out, |
be6b635c AB |
42 | &ipv6_hdr(skb)->daddr, 0, &src) < 0) |
43 | return NF_DROP; | |
44 | ||
45 | nfct_nat(ct)->masq_index = out->ifindex; | |
46 | ||
47 | newrange.flags = range->flags | NF_NAT_RANGE_MAP_IPS; | |
48 | newrange.min_addr.in6 = src; | |
49 | newrange.max_addr.in6 = src; | |
50 | newrange.min_proto = range->min_proto; | |
51 | newrange.max_proto = range->max_proto; | |
52 | ||
53 | return nf_nat_setup_info(ct, &newrange, NF_NAT_MANIP_SRC); | |
54 | } | |
55 | EXPORT_SYMBOL_GPL(nf_nat_masquerade_ipv6); | |
56 | ||
57 | static int device_cmp(struct nf_conn *ct, void *ifindex) | |
58 | { | |
59 | const struct nf_conn_nat *nat = nfct_nat(ct); | |
60 | ||
61 | if (!nat) | |
62 | return 0; | |
63 | if (nf_ct_l3num(ct) != NFPROTO_IPV6) | |
64 | return 0; | |
65 | return nat->masq_index == (int)(long)ifindex; | |
66 | } | |
67 | ||
68 | static int masq_device_event(struct notifier_block *this, | |
69 | unsigned long event, void *ptr) | |
70 | { | |
71 | const struct net_device *dev = netdev_notifier_info_to_dev(ptr); | |
72 | struct net *net = dev_net(dev); | |
73 | ||
74 | if (event == NETDEV_DOWN) | |
75 | nf_ct_iterate_cleanup(net, device_cmp, | |
76 | (void *)(long)dev->ifindex, 0, 0); | |
77 | ||
78 | return NOTIFY_DONE; | |
79 | } | |
80 | ||
81 | static struct notifier_block masq_dev_notifier = { | |
82 | .notifier_call = masq_device_event, | |
83 | }; | |
84 | ||
d93c6258 FW |
85 | struct masq_dev_work { |
86 | struct work_struct work; | |
87 | struct net *net; | |
88 | int ifindex; | |
89 | }; | |
90 | ||
91 | static void iterate_cleanup_work(struct work_struct *work) | |
92 | { | |
93 | struct masq_dev_work *w; | |
94 | long index; | |
95 | ||
96 | w = container_of(work, struct masq_dev_work, work); | |
97 | ||
98 | index = w->ifindex; | |
99 | nf_ct_iterate_cleanup(w->net, device_cmp, (void *)index, 0, 0); | |
100 | ||
101 | put_net(w->net); | |
102 | kfree(w); | |
103 | atomic_dec(&v6_worker_count); | |
104 | module_put(THIS_MODULE); | |
105 | } | |
106 | ||
107 | /* ipv6 inet notifier is an atomic notifier, i.e. we cannot | |
108 | * schedule. | |
109 | * | |
110 | * Unfortunately, nf_ct_iterate_cleanup can run for a long | |
111 | * time if there are lots of conntracks and the system | |
112 | * handles high softirq load, so it frequently calls cond_resched | |
113 | * while iterating the conntrack table. | |
114 | * | |
115 | * So we defer nf_ct_iterate_cleanup walk to the system workqueue. | |
116 | * | |
117 | * As we can have 'a lot' of inet_events (depending on amount | |
118 | * of ipv6 addresses being deleted), we also need to add an upper | |
119 | * limit to the number of queued work items. | |
120 | */ | |
be6b635c AB |
121 | static int masq_inet_event(struct notifier_block *this, |
122 | unsigned long event, void *ptr) | |
123 | { | |
124 | struct inet6_ifaddr *ifa = ptr; | |
d93c6258 FW |
125 | const struct net_device *dev; |
126 | struct masq_dev_work *w; | |
127 | struct net *net; | |
128 | ||
129 | if (event != NETDEV_DOWN || | |
130 | atomic_read(&v6_worker_count) >= MAX_WORK_COUNT) | |
131 | return NOTIFY_DONE; | |
132 | ||
133 | dev = ifa->idev->dev; | |
134 | net = maybe_get_net(dev_net(dev)); | |
135 | if (!net) | |
136 | return NOTIFY_DONE; | |
be6b635c | 137 | |
d93c6258 FW |
138 | if (!try_module_get(THIS_MODULE)) |
139 | goto err_module; | |
140 | ||
141 | w = kmalloc(sizeof(*w), GFP_ATOMIC); | |
142 | if (w) { | |
143 | atomic_inc(&v6_worker_count); | |
144 | ||
145 | INIT_WORK(&w->work, iterate_cleanup_work); | |
146 | w->ifindex = dev->ifindex; | |
147 | w->net = net; | |
148 | schedule_work(&w->work); | |
149 | ||
150 | return NOTIFY_DONE; | |
151 | } | |
152 | ||
153 | module_put(THIS_MODULE); | |
154 | err_module: | |
155 | put_net(net); | |
156 | return NOTIFY_DONE; | |
be6b635c AB |
157 | } |
158 | ||
159 | static struct notifier_block masq_inet_notifier = { | |
160 | .notifier_call = masq_inet_event, | |
161 | }; | |
162 | ||
163 | static atomic_t masquerade_notifier_refcount = ATOMIC_INIT(0); | |
164 | ||
165 | void nf_nat_masquerade_ipv6_register_notifier(void) | |
166 | { | |
167 | /* check if the notifier is already set */ | |
168 | if (atomic_inc_return(&masquerade_notifier_refcount) > 1) | |
169 | return; | |
170 | ||
171 | register_netdevice_notifier(&masq_dev_notifier); | |
172 | register_inet6addr_notifier(&masq_inet_notifier); | |
173 | } | |
174 | EXPORT_SYMBOL_GPL(nf_nat_masquerade_ipv6_register_notifier); | |
175 | ||
176 | void nf_nat_masquerade_ipv6_unregister_notifier(void) | |
177 | { | |
178 | /* check if the notifier still has clients */ | |
179 | if (atomic_dec_return(&masquerade_notifier_refcount) > 0) | |
180 | return; | |
181 | ||
182 | unregister_inet6addr_notifier(&masq_inet_notifier); | |
183 | unregister_netdevice_notifier(&masq_dev_notifier); | |
184 | } | |
185 | EXPORT_SYMBOL_GPL(nf_nat_masquerade_ipv6_unregister_notifier); | |
186 | ||
187 | MODULE_LICENSE("GPL"); | |
188 | MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>"); |