1 /* netfilter.c: look after the filters for various protocols.
2 * Heavily influenced by the old firewall.c by David Bonn and Alan Cox.
4 * Thanks to Rob `CmdrTaco' Malda for not influencing this code in any
7 * Rusty Russell (C)2000 -- This code is GPL.
8 * Patrick McHardy (c) 2006-2012
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>
19 #include <linux/netdevice.h>
20 #include <linux/netfilter_ipv6.h>
21 #include <linux/inetdevice.h>
22 #include <linux/proc_fs.h>
23 #include <linux/mutex.h>
25 #include <linux/rcupdate.h>
26 #include <net/net_namespace.h>
29 #include "nf_internals.h"
31 static DEFINE_MUTEX(afinfo_mutex
);
33 const struct nf_afinfo __rcu
*nf_afinfo
[NFPROTO_NUMPROTO
] __read_mostly
;
34 EXPORT_SYMBOL(nf_afinfo
);
35 const struct nf_ipv6_ops __rcu
*nf_ipv6_ops __read_mostly
;
36 EXPORT_SYMBOL_GPL(nf_ipv6_ops
);
38 DEFINE_PER_CPU(bool, nf_skb_duplicated
);
39 EXPORT_SYMBOL_GPL(nf_skb_duplicated
);
41 int nf_register_afinfo(const struct nf_afinfo
*afinfo
)
43 mutex_lock(&afinfo_mutex
);
44 RCU_INIT_POINTER(nf_afinfo
[afinfo
->family
], afinfo
);
45 mutex_unlock(&afinfo_mutex
);
48 EXPORT_SYMBOL_GPL(nf_register_afinfo
);
50 void nf_unregister_afinfo(const struct nf_afinfo
*afinfo
)
52 mutex_lock(&afinfo_mutex
);
53 RCU_INIT_POINTER(nf_afinfo
[afinfo
->family
], NULL
);
54 mutex_unlock(&afinfo_mutex
);
57 EXPORT_SYMBOL_GPL(nf_unregister_afinfo
);
59 #ifdef HAVE_JUMP_LABEL
60 struct static_key nf_hooks_needed
[NFPROTO_NUMPROTO
][NF_MAX_HOOKS
];
61 EXPORT_SYMBOL(nf_hooks_needed
);
64 static DEFINE_MUTEX(nf_hook_mutex
);
66 /* max hooks per family/hooknum */
67 #define MAX_HOOK_COUNT 1024
69 #define nf_entry_dereference(e) \
70 rcu_dereference_protected(e, lockdep_is_held(&nf_hook_mutex))
72 static struct nf_hook_entries
*allocate_hook_entries_size(u16 num
)
74 struct nf_hook_entries
*e
;
75 size_t alloc
= sizeof(*e
) +
76 sizeof(struct nf_hook_entry
) * num
+
77 sizeof(struct nf_hook_ops
*) * num
;
82 e
= kvzalloc(alloc
, GFP_KERNEL
);
84 e
->num_hook_entries
= num
;
88 static unsigned int accept_all(void *priv
,
90 const struct nf_hook_state
*state
)
92 return NF_ACCEPT
; /* ACCEPT makes nf_hook_slow call next hook */
95 static const struct nf_hook_ops dummy_ops
= {
100 static struct nf_hook_entries
*
101 nf_hook_entries_grow(const struct nf_hook_entries
*old
,
102 const struct nf_hook_ops
*reg
)
104 unsigned int i
, alloc_entries
, nhooks
, old_entries
;
105 struct nf_hook_ops
**orig_ops
= NULL
;
106 struct nf_hook_ops
**new_ops
;
107 struct nf_hook_entries
*new;
108 bool inserted
= false;
111 old_entries
= old
? old
->num_hook_entries
: 0;
114 orig_ops
= nf_hook_entries_get_hook_ops(old
);
116 for (i
= 0; i
< old_entries
; i
++) {
117 if (orig_ops
[i
] != &dummy_ops
)
122 if (alloc_entries
> MAX_HOOK_COUNT
)
123 return ERR_PTR(-E2BIG
);
125 new = allocate_hook_entries_size(alloc_entries
);
127 return ERR_PTR(-ENOMEM
);
129 new_ops
= nf_hook_entries_get_hook_ops(new);
133 while (i
< old_entries
) {
134 if (orig_ops
[i
] == &dummy_ops
) {
138 if (inserted
|| reg
->priority
> orig_ops
[i
]->priority
) {
139 new_ops
[nhooks
] = (void *)orig_ops
[i
];
140 new->hooks
[nhooks
] = old
->hooks
[i
];
143 new_ops
[nhooks
] = (void *)reg
;
144 new->hooks
[nhooks
].hook
= reg
->hook
;
145 new->hooks
[nhooks
].priv
= reg
->priv
;
152 new_ops
[nhooks
] = (void *)reg
;
153 new->hooks
[nhooks
].hook
= reg
->hook
;
154 new->hooks
[nhooks
].priv
= reg
->priv
;
160 static void hooks_validate(const struct nf_hook_entries
*hooks
)
162 #ifdef CONFIG_DEBUG_KERNEL
163 struct nf_hook_ops
**orig_ops
;
167 orig_ops
= nf_hook_entries_get_hook_ops(hooks
);
169 for (i
= 0; i
< hooks
->num_hook_entries
; i
++) {
170 if (orig_ops
[i
] == &dummy_ops
)
173 WARN_ON(orig_ops
[i
]->priority
< prio
);
175 if (orig_ops
[i
]->priority
> prio
)
176 prio
= orig_ops
[i
]->priority
;
182 * __nf_hook_entries_try_shrink - try to shrink hook array
184 * @pp -- location of hook blob
186 * Hook unregistration must always succeed, so to-be-removed hooks
187 * are replaced by a dummy one that will just move to next hook.
189 * This counts the current dummy hooks, attempts to allocate new blob,
190 * copies the live hooks, then replaces and discards old one.
194 * Returns address to free, or NULL.
196 static void *__nf_hook_entries_try_shrink(struct nf_hook_entries __rcu
**pp
)
198 struct nf_hook_entries
*old
, *new = NULL
;
199 unsigned int i
, j
, skip
= 0, hook_entries
;
200 struct nf_hook_ops
**orig_ops
;
201 struct nf_hook_ops
**new_ops
;
203 old
= nf_entry_dereference(*pp
);
204 if (WARN_ON_ONCE(!old
))
207 orig_ops
= nf_hook_entries_get_hook_ops(old
);
208 for (i
= 0; i
< old
->num_hook_entries
; i
++) {
209 if (orig_ops
[i
] == &dummy_ops
)
213 /* if skip == hook_entries all hooks have been removed */
214 hook_entries
= old
->num_hook_entries
;
215 if (skip
== hook_entries
)
221 hook_entries
-= skip
;
222 new = allocate_hook_entries_size(hook_entries
);
226 new_ops
= nf_hook_entries_get_hook_ops(new);
227 for (i
= 0, j
= 0; i
< old
->num_hook_entries
; i
++) {
228 if (orig_ops
[i
] == &dummy_ops
)
230 new->hooks
[j
] = old
->hooks
[i
];
231 new_ops
[j
] = (void *)orig_ops
[i
];
236 rcu_assign_pointer(*pp
, new);
240 static struct nf_hook_entries __rcu
**nf_hook_entry_head(struct net
*net
, const struct nf_hook_ops
*reg
)
242 if (reg
->pf
!= NFPROTO_NETDEV
)
243 return net
->nf
.hooks
[reg
->pf
]+reg
->hooknum
;
245 #ifdef CONFIG_NETFILTER_INGRESS
246 if (reg
->hooknum
== NF_NETDEV_INGRESS
) {
247 if (reg
->dev
&& dev_net(reg
->dev
) == net
)
248 return ®
->dev
->nf_hooks_ingress
;
255 int nf_register_net_hook(struct net
*net
, const struct nf_hook_ops
*reg
)
257 struct nf_hook_entries
*p
, *new_hooks
;
258 struct nf_hook_entries __rcu
**pp
;
260 if (reg
->pf
== NFPROTO_NETDEV
) {
261 #ifndef CONFIG_NETFILTER_INGRESS
262 if (reg
->hooknum
== NF_NETDEV_INGRESS
)
265 if (reg
->hooknum
!= NF_NETDEV_INGRESS
||
266 !reg
->dev
|| dev_net(reg
->dev
) != net
)
270 pp
= nf_hook_entry_head(net
, reg
);
274 mutex_lock(&nf_hook_mutex
);
276 p
= nf_entry_dereference(*pp
);
277 new_hooks
= nf_hook_entries_grow(p
, reg
);
279 if (!IS_ERR(new_hooks
))
280 rcu_assign_pointer(*pp
, new_hooks
);
282 mutex_unlock(&nf_hook_mutex
);
283 if (IS_ERR(new_hooks
))
284 return PTR_ERR(new_hooks
);
286 hooks_validate(new_hooks
);
287 #ifdef CONFIG_NETFILTER_INGRESS
288 if (reg
->pf
== NFPROTO_NETDEV
&& reg
->hooknum
== NF_NETDEV_INGRESS
)
289 net_inc_ingress_queue();
291 #ifdef HAVE_JUMP_LABEL
292 static_key_slow_inc(&nf_hooks_needed
[reg
->pf
][reg
->hooknum
]);
295 BUG_ON(p
== new_hooks
);
299 EXPORT_SYMBOL(nf_register_net_hook
);
302 * __nf_unregister_net_hook - remove a hook from blob
304 * @oldp: current address of hook blob
305 * @unreg: hook to unregister
307 * This cannot fail, hook unregistration must always succeed.
308 * Therefore replace the to-be-removed hook with a dummy hook.
310 static void __nf_unregister_net_hook(struct nf_hook_entries
*old
,
311 const struct nf_hook_ops
*unreg
)
313 struct nf_hook_ops
**orig_ops
;
317 orig_ops
= nf_hook_entries_get_hook_ops(old
);
318 for (i
= 0; i
< old
->num_hook_entries
; i
++) {
319 if (orig_ops
[i
] != unreg
)
321 WRITE_ONCE(old
->hooks
[i
].hook
, accept_all
);
322 WRITE_ONCE(orig_ops
[i
], &dummy_ops
);
328 #ifdef CONFIG_NETFILTER_INGRESS
329 if (unreg
->pf
== NFPROTO_NETDEV
&& unreg
->hooknum
== NF_NETDEV_INGRESS
)
330 net_dec_ingress_queue();
332 #ifdef HAVE_JUMP_LABEL
333 static_key_slow_dec(&nf_hooks_needed
[unreg
->pf
][unreg
->hooknum
]);
336 WARN_ONCE(1, "hook not found, pf %d num %d", unreg
->pf
, unreg
->hooknum
);
340 void nf_unregister_net_hook(struct net
*net
, const struct nf_hook_ops
*reg
)
342 struct nf_hook_entries __rcu
**pp
;
343 struct nf_hook_entries
*p
;
346 pp
= nf_hook_entry_head(net
, reg
);
350 mutex_lock(&nf_hook_mutex
);
352 p
= nf_entry_dereference(*pp
);
353 if (WARN_ON_ONCE(!p
)) {
354 mutex_unlock(&nf_hook_mutex
);
358 __nf_unregister_net_hook(p
, reg
);
360 p
= __nf_hook_entries_try_shrink(pp
);
361 mutex_unlock(&nf_hook_mutex
);
367 /* other cpu might still process nfqueue verdict that used reg */
368 nfq
= nf_queue_nf_hook_drop(net
);
373 EXPORT_SYMBOL(nf_unregister_net_hook
);
375 int nf_register_net_hooks(struct net
*net
, const struct nf_hook_ops
*reg
,
381 for (i
= 0; i
< n
; i
++) {
382 err
= nf_register_net_hook(net
, ®
[i
]);
390 nf_unregister_net_hooks(net
, reg
, i
);
393 EXPORT_SYMBOL(nf_register_net_hooks
);
395 void nf_unregister_net_hooks(struct net
*net
, const struct nf_hook_ops
*reg
,
396 unsigned int hookcount
)
398 struct nf_hook_entries
*to_free
[16], *p
;
399 struct nf_hook_entries __rcu
**pp
;
400 unsigned int i
, j
, n
;
402 mutex_lock(&nf_hook_mutex
);
403 for (i
= 0; i
< hookcount
; i
++) {
404 pp
= nf_hook_entry_head(net
, ®
[i
]);
408 p
= nf_entry_dereference(*pp
);
409 if (WARN_ON_ONCE(!p
))
411 __nf_unregister_net_hook(p
, ®
[i
]);
413 mutex_unlock(&nf_hook_mutex
);
416 n
= min_t(unsigned int, hookcount
, ARRAY_SIZE(to_free
));
418 mutex_lock(&nf_hook_mutex
);
420 for (i
= 0, j
= 0; i
< hookcount
&& j
< n
; i
++) {
421 pp
= nf_hook_entry_head(net
, ®
[i
]);
425 p
= nf_entry_dereference(*pp
);
429 to_free
[j
] = __nf_hook_entries_try_shrink(pp
);
434 mutex_unlock(&nf_hook_mutex
);
441 /* need 2nd synchronize_net() if nfqueue is used, skb
442 * can get reinjected right before nf_queue_hook_drop()
444 nfq
= nf_queue_nf_hook_drop(net
);
448 for (i
= 0; i
< j
; i
++)
454 } while (hookcount
> 0);
456 EXPORT_SYMBOL(nf_unregister_net_hooks
);
458 /* Returns 1 if okfn() needs to be executed by the caller,
459 * -EPERM for NF_DROP, 0 otherwise. Caller must hold rcu_read_lock. */
460 int nf_hook_slow(struct sk_buff
*skb
, struct nf_hook_state
*state
,
461 const struct nf_hook_entries
*e
, unsigned int s
)
463 unsigned int verdict
;
466 for (; s
< e
->num_hook_entries
; s
++) {
467 verdict
= nf_hook_entry_hookfn(&e
->hooks
[s
], skb
, state
);
468 switch (verdict
& NF_VERDICT_MASK
) {
473 ret
= NF_DROP_GETERR(verdict
);
478 ret
= nf_queue(skb
, state
, e
, s
, verdict
);
483 /* Implicit handling for NF_STOLEN, as well as any other
484 * non conventional verdicts.
492 EXPORT_SYMBOL(nf_hook_slow
);
495 int skb_make_writable(struct sk_buff
*skb
, unsigned int writable_len
)
497 if (writable_len
> skb
->len
)
500 /* Not exclusive use of packet? Must copy. */
501 if (!skb_cloned(skb
)) {
502 if (writable_len
<= skb_headlen(skb
))
504 } else if (skb_clone_writable(skb
, writable_len
))
507 if (writable_len
<= skb_headlen(skb
))
510 writable_len
-= skb_headlen(skb
);
512 return !!__pskb_pull_tail(skb
, writable_len
);
514 EXPORT_SYMBOL(skb_make_writable
);
516 /* This needs to be compiled in any case to avoid dependencies between the
517 * nfnetlink_queue code and nf_conntrack.
519 struct nfnl_ct_hook __rcu
*nfnl_ct_hook __read_mostly
;
520 EXPORT_SYMBOL_GPL(nfnl_ct_hook
);
522 #if IS_ENABLED(CONFIG_NF_CONNTRACK)
523 /* This does not belong here, but locally generated errors need it if connection
524 tracking in use: without this, connection may not be in hash table, and hence
525 manufactured ICMP or RST packets will not be associated with it. */
526 void (*ip_ct_attach
)(struct sk_buff
*, const struct sk_buff
*)
528 EXPORT_SYMBOL(ip_ct_attach
);
530 void nf_ct_attach(struct sk_buff
*new, const struct sk_buff
*skb
)
532 void (*attach
)(struct sk_buff
*, const struct sk_buff
*);
536 attach
= rcu_dereference(ip_ct_attach
);
542 EXPORT_SYMBOL(nf_ct_attach
);
544 void (*nf_ct_destroy
)(struct nf_conntrack
*) __rcu __read_mostly
;
545 EXPORT_SYMBOL(nf_ct_destroy
);
547 void nf_conntrack_destroy(struct nf_conntrack
*nfct
)
549 void (*destroy
)(struct nf_conntrack
*);
552 destroy
= rcu_dereference(nf_ct_destroy
);
553 BUG_ON(destroy
== NULL
);
557 EXPORT_SYMBOL(nf_conntrack_destroy
);
559 /* Built-in default zone used e.g. by modules. */
560 const struct nf_conntrack_zone nf_ct_zone_dflt
= {
561 .id
= NF_CT_DEFAULT_ZONE_ID
,
562 .dir
= NF_CT_DEFAULT_ZONE_DIR
,
564 EXPORT_SYMBOL_GPL(nf_ct_zone_dflt
);
565 #endif /* CONFIG_NF_CONNTRACK */
567 #ifdef CONFIG_NF_NAT_NEEDED
568 void (*nf_nat_decode_session_hook
)(struct sk_buff
*, struct flowi
*);
569 EXPORT_SYMBOL(nf_nat_decode_session_hook
);
572 static int __net_init
netfilter_net_init(struct net
*net
)
576 for (i
= 0; i
< ARRAY_SIZE(net
->nf
.hooks
); i
++) {
577 for (h
= 0; h
< NF_MAX_HOOKS
; h
++)
578 RCU_INIT_POINTER(net
->nf
.hooks
[i
][h
], NULL
);
581 #ifdef CONFIG_PROC_FS
582 net
->nf
.proc_netfilter
= proc_net_mkdir(net
, "netfilter",
584 if (!net
->nf
.proc_netfilter
) {
585 if (!net_eq(net
, &init_net
))
586 pr_err("cannot create netfilter proc entry");
595 static void __net_exit
netfilter_net_exit(struct net
*net
)
597 remove_proc_entry("netfilter", net
->proc_net
);
600 static struct pernet_operations netfilter_net_ops
= {
601 .init
= netfilter_net_init
,
602 .exit
= netfilter_net_exit
,
605 int __init
netfilter_init(void)
609 ret
= register_pernet_subsys(&netfilter_net_ops
);
613 ret
= netfilter_log_init();
619 unregister_pernet_subsys(&netfilter_net_ops
);