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Commit | Line | Data |
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601e68e1 | 1 | /* netfilter.c: look after the filters for various protocols. |
f6ebe77f HW |
2 | * Heavily influenced by the old firewall.c by David Bonn and Alan Cox. |
3 | * | |
4 | * Thanks to Rob `CmdrTaco' Malda for not influencing this code in any | |
5 | * way. | |
6 | * | |
7 | * Rusty Russell (C)2000 -- This code is GPL. | |
f229f6ce | 8 | * Patrick McHardy (c) 2006-2012 |
f6ebe77f | 9 | */ |
f6ebe77f HW |
10 | #include <linux/kernel.h> |
11 | #include <linux/netfilter.h> | |
12 | #include <net/protocol.h> | |
13 | #include <linux/init.h> | |
14 | #include <linux/skbuff.h> | |
15 | #include <linux/wait.h> | |
16 | #include <linux/module.h> | |
17 | #include <linux/interrupt.h> | |
18 | #include <linux/if.h> | |
19 | #include <linux/netdevice.h> | |
20 | #include <linux/inetdevice.h> | |
21 | #include <linux/proc_fs.h> | |
d486dd1f | 22 | #include <linux/mutex.h> |
5a0e3ad6 | 23 | #include <linux/slab.h> |
457c4cbc | 24 | #include <net/net_namespace.h> |
f6ebe77f HW |
25 | #include <net/sock.h> |
26 | ||
27 | #include "nf_internals.h" | |
28 | ||
d486dd1f | 29 | static DEFINE_MUTEX(afinfo_mutex); |
bce8032e | 30 | |
0906a372 | 31 | const struct nf_afinfo __rcu *nf_afinfo[NFPROTO_NUMPROTO] __read_mostly; |
bce8032e | 32 | EXPORT_SYMBOL(nf_afinfo); |
2a7851bf FW |
33 | const struct nf_ipv6_ops __rcu *nf_ipv6_ops __read_mostly; |
34 | EXPORT_SYMBOL_GPL(nf_ipv6_ops); | |
bce8032e | 35 | |
1e796fda | 36 | int nf_register_afinfo(const struct nf_afinfo *afinfo) |
bce8032e | 37 | { |
d486dd1f PM |
38 | int err; |
39 | ||
40 | err = mutex_lock_interruptible(&afinfo_mutex); | |
41 | if (err < 0) | |
42 | return err; | |
a9b3cd7f | 43 | RCU_INIT_POINTER(nf_afinfo[afinfo->family], afinfo); |
d486dd1f | 44 | mutex_unlock(&afinfo_mutex); |
bce8032e PM |
45 | return 0; |
46 | } | |
47 | EXPORT_SYMBOL_GPL(nf_register_afinfo); | |
48 | ||
1e796fda | 49 | void nf_unregister_afinfo(const struct nf_afinfo *afinfo) |
bce8032e | 50 | { |
d486dd1f | 51 | mutex_lock(&afinfo_mutex); |
a9b3cd7f | 52 | RCU_INIT_POINTER(nf_afinfo[afinfo->family], NULL); |
d486dd1f | 53 | mutex_unlock(&afinfo_mutex); |
bce8032e PM |
54 | synchronize_rcu(); |
55 | } | |
56 | EXPORT_SYMBOL_GPL(nf_unregister_afinfo); | |
57 | ||
7e9c6eeb | 58 | struct list_head nf_hooks[NFPROTO_NUMPROTO][NF_MAX_HOOKS] __read_mostly; |
f6ebe77f | 59 | EXPORT_SYMBOL(nf_hooks); |
a2d7ec58 ED |
60 | |
61 | #if defined(CONFIG_JUMP_LABEL) | |
c5905afb | 62 | struct static_key nf_hooks_needed[NFPROTO_NUMPROTO][NF_MAX_HOOKS]; |
a2d7ec58 ED |
63 | EXPORT_SYMBOL(nf_hooks_needed); |
64 | #endif | |
65 | ||
fd706d69 | 66 | static DEFINE_MUTEX(nf_hook_mutex); |
f6ebe77f HW |
67 | |
68 | int nf_register_hook(struct nf_hook_ops *reg) | |
69 | { | |
4c610979 | 70 | struct nf_hook_ops *elem; |
fd706d69 | 71 | int err; |
f6ebe77f | 72 | |
fd706d69 PM |
73 | err = mutex_lock_interruptible(&nf_hook_mutex); |
74 | if (err < 0) | |
75 | return err; | |
4c610979 LZ |
76 | list_for_each_entry(elem, &nf_hooks[reg->pf][reg->hooknum], list) { |
77 | if (reg->priority < elem->priority) | |
f6ebe77f HW |
78 | break; |
79 | } | |
4c610979 | 80 | list_add_rcu(®->list, elem->list.prev); |
fd706d69 | 81 | mutex_unlock(&nf_hook_mutex); |
a2d7ec58 | 82 | #if defined(CONFIG_JUMP_LABEL) |
c5905afb | 83 | static_key_slow_inc(&nf_hooks_needed[reg->pf][reg->hooknum]); |
a2d7ec58 | 84 | #endif |
f6ebe77f HW |
85 | return 0; |
86 | } | |
87 | EXPORT_SYMBOL(nf_register_hook); | |
88 | ||
89 | void nf_unregister_hook(struct nf_hook_ops *reg) | |
90 | { | |
fd706d69 | 91 | mutex_lock(&nf_hook_mutex); |
f6ebe77f | 92 | list_del_rcu(®->list); |
fd706d69 | 93 | mutex_unlock(&nf_hook_mutex); |
a2d7ec58 | 94 | #if defined(CONFIG_JUMP_LABEL) |
c5905afb | 95 | static_key_slow_dec(&nf_hooks_needed[reg->pf][reg->hooknum]); |
a2d7ec58 | 96 | #endif |
f6ebe77f HW |
97 | synchronize_net(); |
98 | } | |
99 | EXPORT_SYMBOL(nf_unregister_hook); | |
100 | ||
972d1cb1 PM |
101 | int nf_register_hooks(struct nf_hook_ops *reg, unsigned int n) |
102 | { | |
103 | unsigned int i; | |
104 | int err = 0; | |
105 | ||
106 | for (i = 0; i < n; i++) { | |
107 | err = nf_register_hook(®[i]); | |
108 | if (err) | |
109 | goto err; | |
110 | } | |
111 | return err; | |
112 | ||
113 | err: | |
114 | if (i > 0) | |
115 | nf_unregister_hooks(reg, i); | |
116 | return err; | |
117 | } | |
118 | EXPORT_SYMBOL(nf_register_hooks); | |
119 | ||
120 | void nf_unregister_hooks(struct nf_hook_ops *reg, unsigned int n) | |
121 | { | |
f68c5301 CG |
122 | while (n-- > 0) |
123 | nf_unregister_hook(®[n]); | |
972d1cb1 PM |
124 | } |
125 | EXPORT_SYMBOL(nf_unregister_hooks); | |
126 | ||
f6ebe77f | 127 | unsigned int nf_iterate(struct list_head *head, |
3db05fea | 128 | struct sk_buff *skb, |
76108cea | 129 | unsigned int hook, |
f6ebe77f HW |
130 | const struct net_device *indev, |
131 | const struct net_device *outdev, | |
2a6decfd | 132 | struct nf_hook_ops **elemp, |
f6ebe77f HW |
133 | int (*okfn)(struct sk_buff *), |
134 | int hook_thresh) | |
135 | { | |
136 | unsigned int verdict; | |
137 | ||
138 | /* | |
139 | * The caller must not block between calls to this | |
140 | * function because of risk of continuing from deleted element. | |
141 | */ | |
2a6decfd MW |
142 | list_for_each_entry_continue_rcu((*elemp), head, list) { |
143 | if (hook_thresh > (*elemp)->priority) | |
f6ebe77f HW |
144 | continue; |
145 | ||
146 | /* Optimization: we don't need to hold module | |
601e68e1 | 147 | reference here, since function can't sleep. --RR */ |
de9963f0 | 148 | repeat: |
2a6decfd | 149 | verdict = (*elemp)->hook(hook, skb, indev, outdev, okfn); |
f6ebe77f HW |
150 | if (verdict != NF_ACCEPT) { |
151 | #ifdef CONFIG_NETFILTER_DEBUG | |
152 | if (unlikely((verdict & NF_VERDICT_MASK) | |
153 | > NF_MAX_VERDICT)) { | |
154 | NFDEBUG("Evil return from %p(%u).\n", | |
2a6decfd | 155 | (*elemp)->hook, hook); |
f6ebe77f HW |
156 | continue; |
157 | } | |
158 | #endif | |
2a6decfd | 159 | if (verdict != NF_REPEAT) |
f6ebe77f | 160 | return verdict; |
de9963f0 | 161 | goto repeat; |
f6ebe77f HW |
162 | } |
163 | } | |
164 | return NF_ACCEPT; | |
165 | } | |
166 | ||
167 | ||
168 | /* Returns 1 if okfn() needs to be executed by the caller, | |
169 | * -EPERM for NF_DROP, 0 otherwise. */ | |
76108cea | 170 | int nf_hook_slow(u_int8_t pf, unsigned int hook, struct sk_buff *skb, |
f6ebe77f HW |
171 | struct net_device *indev, |
172 | struct net_device *outdev, | |
173 | int (*okfn)(struct sk_buff *), | |
174 | int hook_thresh) | |
175 | { | |
2a6decfd | 176 | struct nf_hook_ops *elem; |
f6ebe77f HW |
177 | unsigned int verdict; |
178 | int ret = 0; | |
179 | ||
180 | /* We may already have this, but read-locks nest anyway */ | |
181 | rcu_read_lock(); | |
182 | ||
2a6decfd | 183 | elem = list_entry_rcu(&nf_hooks[pf][hook], struct nf_hook_ops, list); |
f6ebe77f | 184 | next_hook: |
3db05fea | 185 | verdict = nf_iterate(&nf_hooks[pf][hook], skb, hook, indev, |
f6ebe77f HW |
186 | outdev, &elem, okfn, hook_thresh); |
187 | if (verdict == NF_ACCEPT || verdict == NF_STOP) { | |
188 | ret = 1; | |
da683650 | 189 | } else if ((verdict & NF_VERDICT_MASK) == NF_DROP) { |
3db05fea | 190 | kfree_skb(skb); |
f615df76 | 191 | ret = NF_DROP_GETERR(verdict); |
da683650 EP |
192 | if (ret == 0) |
193 | ret = -EPERM; | |
f9c63990 | 194 | } else if ((verdict & NF_VERDICT_MASK) == NF_QUEUE) { |
1c15b677 MW |
195 | int err = nf_queue(skb, elem, pf, hook, indev, outdev, okfn, |
196 | verdict >> NF_VERDICT_QBITS); | |
563e1232 FW |
197 | if (err < 0) { |
198 | if (err == -ECANCELED) | |
06cdb634 | 199 | goto next_hook; |
563e1232 | 200 | if (err == -ESRCH && |
94b27cc3 FW |
201 | (verdict & NF_VERDICT_FLAG_QUEUE_BYPASS)) |
202 | goto next_hook; | |
06cdb634 FW |
203 | kfree_skb(skb); |
204 | } | |
f6ebe77f | 205 | } |
f6ebe77f HW |
206 | rcu_read_unlock(); |
207 | return ret; | |
208 | } | |
209 | EXPORT_SYMBOL(nf_hook_slow); | |
210 | ||
211 | ||
37d41879 | 212 | int skb_make_writable(struct sk_buff *skb, unsigned int writable_len) |
f6ebe77f | 213 | { |
37d41879 | 214 | if (writable_len > skb->len) |
f6ebe77f HW |
215 | return 0; |
216 | ||
217 | /* Not exclusive use of packet? Must copy. */ | |
37d41879 HX |
218 | if (!skb_cloned(skb)) { |
219 | if (writable_len <= skb_headlen(skb)) | |
220 | return 1; | |
221 | } else if (skb_clone_writable(skb, writable_len)) | |
222 | return 1; | |
223 | ||
224 | if (writable_len <= skb_headlen(skb)) | |
225 | writable_len = 0; | |
226 | else | |
227 | writable_len -= skb_headlen(skb); | |
228 | ||
229 | return !!__pskb_pull_tail(skb, writable_len); | |
f6ebe77f HW |
230 | } |
231 | EXPORT_SYMBOL(skb_make_writable); | |
232 | ||
c0cd1156 | 233 | #if IS_ENABLED(CONFIG_NF_CONNTRACK) |
f6ebe77f HW |
234 | /* This does not belong here, but locally generated errors need it if connection |
235 | tracking in use: without this, connection may not be in hash table, and hence | |
236 | manufactured ICMP or RST packets will not be associated with it. */ | |
312a0c16 PM |
237 | void (*ip_ct_attach)(struct sk_buff *, const struct sk_buff *) |
238 | __rcu __read_mostly; | |
f6ebe77f HW |
239 | EXPORT_SYMBOL(ip_ct_attach); |
240 | ||
312a0c16 | 241 | void nf_ct_attach(struct sk_buff *new, const struct sk_buff *skb) |
f6ebe77f | 242 | { |
312a0c16 | 243 | void (*attach)(struct sk_buff *, const struct sk_buff *); |
f6ebe77f | 244 | |
c3a47ab3 PM |
245 | if (skb->nfct) { |
246 | rcu_read_lock(); | |
247 | attach = rcu_dereference(ip_ct_attach); | |
248 | if (attach) | |
249 | attach(new, skb); | |
250 | rcu_read_unlock(); | |
f6ebe77f HW |
251 | } |
252 | } | |
253 | EXPORT_SYMBOL(nf_ct_attach); | |
de6e05c4 | 254 | |
0e60ebe0 | 255 | void (*nf_ct_destroy)(struct nf_conntrack *) __rcu __read_mostly; |
de6e05c4 YK |
256 | EXPORT_SYMBOL(nf_ct_destroy); |
257 | ||
258 | void nf_conntrack_destroy(struct nf_conntrack *nfct) | |
259 | { | |
260 | void (*destroy)(struct nf_conntrack *); | |
261 | ||
262 | rcu_read_lock(); | |
263 | destroy = rcu_dereference(nf_ct_destroy); | |
264 | BUG_ON(destroy == NULL); | |
265 | destroy(nfct); | |
266 | rcu_read_unlock(); | |
267 | } | |
268 | EXPORT_SYMBOL(nf_conntrack_destroy); | |
9cb01766 | 269 | |
5a05fae5 | 270 | struct nfq_ct_hook __rcu *nfq_ct_hook __read_mostly; |
9cb01766 PNA |
271 | EXPORT_SYMBOL_GPL(nfq_ct_hook); |
272 | ||
d584a61a PNA |
273 | struct nfq_ct_nat_hook __rcu *nfq_ct_nat_hook __read_mostly; |
274 | EXPORT_SYMBOL_GPL(nfq_ct_nat_hook); | |
275 | ||
de6e05c4 | 276 | #endif /* CONFIG_NF_CONNTRACK */ |
f6ebe77f | 277 | |
c7232c99 PM |
278 | #ifdef CONFIG_NF_NAT_NEEDED |
279 | void (*nf_nat_decode_session_hook)(struct sk_buff *, struct flowi *); | |
280 | EXPORT_SYMBOL(nf_nat_decode_session_hook); | |
281 | #endif | |
282 | ||
f3c1a44a G |
283 | static int __net_init netfilter_net_init(struct net *net) |
284 | { | |
285 | #ifdef CONFIG_PROC_FS | |
286 | net->nf.proc_netfilter = proc_net_mkdir(net, "netfilter", | |
287 | net->proc_net); | |
12202fa7 PNA |
288 | if (!net->nf.proc_netfilter) { |
289 | if (!net_eq(net, &init_net)) | |
290 | pr_err("cannot create netfilter proc entry"); | |
291 | ||
f3c1a44a G |
292 | return -ENOMEM; |
293 | } | |
294 | #endif | |
295 | return 0; | |
296 | } | |
297 | ||
298 | static void __net_exit netfilter_net_exit(struct net *net) | |
299 | { | |
300 | remove_proc_entry("netfilter", net->proc_net); | |
301 | } | |
302 | ||
303 | static struct pernet_operations netfilter_net_ops = { | |
304 | .init = netfilter_net_init, | |
305 | .exit = netfilter_net_exit, | |
306 | }; | |
307 | ||
6d11cfdb | 308 | int __init netfilter_init(void) |
f6ebe77f | 309 | { |
6d11cfdb PNA |
310 | int i, h, ret; |
311 | ||
7e9c6eeb | 312 | for (i = 0; i < ARRAY_SIZE(nf_hooks); i++) { |
f6ebe77f HW |
313 | for (h = 0; h < NF_MAX_HOOKS; h++) |
314 | INIT_LIST_HEAD(&nf_hooks[i][h]); | |
315 | } | |
316 | ||
6d11cfdb PNA |
317 | ret = register_pernet_subsys(&netfilter_net_ops); |
318 | if (ret < 0) | |
319 | goto err; | |
320 | ||
321 | ret = netfilter_log_init(); | |
322 | if (ret < 0) | |
323 | goto err_pernet; | |
f6ebe77f | 324 | |
6d11cfdb PNA |
325 | return 0; |
326 | err_pernet: | |
327 | unregister_pernet_subsys(&netfilter_net_ops); | |
328 | err: | |
329 | return ret; | |
f6ebe77f | 330 | } |