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
9 #include <linux/kernel.h>
10 #include <linux/netfilter.h>
11 #include <net/protocol.h>
12 #include <linux/init.h>
13 #include <linux/skbuff.h>
14 #include <linux/wait.h>
15 #include <linux/module.h>
16 #include <linux/interrupt.h>
18 #include <linux/netdevice.h>
19 #include <linux/netfilter_ipv6.h>
20 #include <linux/inetdevice.h>
21 #include <linux/proc_fs.h>
22 #include <linux/mutex.h>
24 #include <linux/rcupdate.h>
25 #include <net/net_namespace.h>
26 #include <net/netfilter/nf_queue.h>
29 #include "nf_internals.h"
31 const struct nf_ipv6_ops __rcu *nf_ipv6_ops __read_mostly;
32 EXPORT_SYMBOL_GPL(nf_ipv6_ops);
34 DEFINE_PER_CPU(bool, nf_skb_duplicated);
35 EXPORT_SYMBOL_GPL(nf_skb_duplicated);
37 #ifdef CONFIG_JUMP_LABEL
38 struct static_key nf_hooks_needed[NFPROTO_NUMPROTO][NF_MAX_HOOKS];
39 EXPORT_SYMBOL(nf_hooks_needed);
42 static DEFINE_MUTEX(nf_hook_mutex);
44 /* max hooks per family/hooknum */
45 #define MAX_HOOK_COUNT 1024
47 #define nf_entry_dereference(e) \
48 rcu_dereference_protected(e, lockdep_is_held(&nf_hook_mutex))
50 static struct nf_hook_entries *allocate_hook_entries_size(u16 num)
52 struct nf_hook_entries *e;
53 size_t alloc = sizeof(*e) +
54 sizeof(struct nf_hook_entry) * num +
55 sizeof(struct nf_hook_ops *) * num +
56 sizeof(struct nf_hook_entries_rcu_head);
61 e = kvzalloc(alloc, GFP_KERNEL);
63 e->num_hook_entries = num;
67 static void __nf_hook_entries_free(struct rcu_head *h)
69 struct nf_hook_entries_rcu_head *head;
71 head = container_of(h, struct nf_hook_entries_rcu_head, head);
72 kvfree(head->allocation);
75 static void nf_hook_entries_free(struct nf_hook_entries *e)
77 struct nf_hook_entries_rcu_head *head;
78 struct nf_hook_ops **ops;
84 num = e->num_hook_entries;
85 ops = nf_hook_entries_get_hook_ops(e);
86 head = (void *)&ops[num];
88 call_rcu(&head->head, __nf_hook_entries_free);
91 static unsigned int accept_all(void *priv,
93 const struct nf_hook_state *state)
95 return NF_ACCEPT; /* ACCEPT makes nf_hook_slow call next hook */
98 static const struct nf_hook_ops dummy_ops = {
103 static struct nf_hook_entries *
104 nf_hook_entries_grow(const struct nf_hook_entries *old,
105 const struct nf_hook_ops *reg)
107 unsigned int i, alloc_entries, nhooks, old_entries;
108 struct nf_hook_ops **orig_ops = NULL;
109 struct nf_hook_ops **new_ops;
110 struct nf_hook_entries *new;
111 bool inserted = false;
114 old_entries = old ? old->num_hook_entries : 0;
117 orig_ops = nf_hook_entries_get_hook_ops(old);
119 for (i = 0; i < old_entries; i++) {
120 if (orig_ops[i] != &dummy_ops)
125 if (alloc_entries > MAX_HOOK_COUNT)
126 return ERR_PTR(-E2BIG);
128 new = allocate_hook_entries_size(alloc_entries);
130 return ERR_PTR(-ENOMEM);
132 new_ops = nf_hook_entries_get_hook_ops(new);
136 while (i < old_entries) {
137 if (orig_ops[i] == &dummy_ops) {
142 if (inserted || reg->priority > orig_ops[i]->priority) {
143 new_ops[nhooks] = (void *)orig_ops[i];
144 new->hooks[nhooks] = old->hooks[i];
147 new_ops[nhooks] = (void *)reg;
148 new->hooks[nhooks].hook = reg->hook;
149 new->hooks[nhooks].priv = reg->priv;
156 new_ops[nhooks] = (void *)reg;
157 new->hooks[nhooks].hook = reg->hook;
158 new->hooks[nhooks].priv = reg->priv;
164 static void hooks_validate(const struct nf_hook_entries *hooks)
166 #ifdef CONFIG_DEBUG_MISC
167 struct nf_hook_ops **orig_ops;
171 orig_ops = nf_hook_entries_get_hook_ops(hooks);
173 for (i = 0; i < hooks->num_hook_entries; i++) {
174 if (orig_ops[i] == &dummy_ops)
177 WARN_ON(orig_ops[i]->priority < prio);
179 if (orig_ops[i]->priority > prio)
180 prio = orig_ops[i]->priority;
185 int nf_hook_entries_insert_raw(struct nf_hook_entries __rcu **pp,
186 const struct nf_hook_ops *reg)
188 struct nf_hook_entries *new_hooks;
189 struct nf_hook_entries *p;
191 p = rcu_dereference_raw(*pp);
192 new_hooks = nf_hook_entries_grow(p, reg);
193 if (IS_ERR(new_hooks))
194 return PTR_ERR(new_hooks);
196 hooks_validate(new_hooks);
198 rcu_assign_pointer(*pp, new_hooks);
200 BUG_ON(p == new_hooks);
201 nf_hook_entries_free(p);
204 EXPORT_SYMBOL_GPL(nf_hook_entries_insert_raw);
207 * __nf_hook_entries_try_shrink - try to shrink hook array
209 * @old -- current hook blob at @pp
210 * @pp -- location of hook blob
212 * Hook unregistration must always succeed, so to-be-removed hooks
213 * are replaced by a dummy one that will just move to next hook.
215 * This counts the current dummy hooks, attempts to allocate new blob,
216 * copies the live hooks, then replaces and discards old one.
220 * Returns address to free, or NULL.
222 static void *__nf_hook_entries_try_shrink(struct nf_hook_entries *old,
223 struct nf_hook_entries __rcu **pp)
225 unsigned int i, j, skip = 0, hook_entries;
226 struct nf_hook_entries *new = NULL;
227 struct nf_hook_ops **orig_ops;
228 struct nf_hook_ops **new_ops;
230 if (WARN_ON_ONCE(!old))
233 orig_ops = nf_hook_entries_get_hook_ops(old);
234 for (i = 0; i < old->num_hook_entries; i++) {
235 if (orig_ops[i] == &dummy_ops)
239 /* if skip == hook_entries all hooks have been removed */
240 hook_entries = old->num_hook_entries;
241 if (skip == hook_entries)
247 hook_entries -= skip;
248 new = allocate_hook_entries_size(hook_entries);
252 new_ops = nf_hook_entries_get_hook_ops(new);
253 for (i = 0, j = 0; i < old->num_hook_entries; i++) {
254 if (orig_ops[i] == &dummy_ops)
256 new->hooks[j] = old->hooks[i];
257 new_ops[j] = (void *)orig_ops[i];
262 rcu_assign_pointer(*pp, new);
266 static struct nf_hook_entries __rcu **
267 nf_hook_entry_head(struct net *net, int pf, unsigned int hooknum,
268 struct net_device *dev)
273 #ifdef CONFIG_NETFILTER_FAMILY_ARP
275 if (WARN_ON_ONCE(ARRAY_SIZE(net->nf.hooks_arp) <= hooknum))
277 return net->nf.hooks_arp + hooknum;
279 #ifdef CONFIG_NETFILTER_FAMILY_BRIDGE
281 if (WARN_ON_ONCE(ARRAY_SIZE(net->nf.hooks_bridge) <= hooknum))
283 return net->nf.hooks_bridge + hooknum;
286 if (WARN_ON_ONCE(ARRAY_SIZE(net->nf.hooks_ipv4) <= hooknum))
288 return net->nf.hooks_ipv4 + hooknum;
290 if (WARN_ON_ONCE(ARRAY_SIZE(net->nf.hooks_ipv6) <= hooknum))
292 return net->nf.hooks_ipv6 + hooknum;
293 #if IS_ENABLED(CONFIG_DECNET)
295 if (WARN_ON_ONCE(ARRAY_SIZE(net->nf.hooks_decnet) <= hooknum))
297 return net->nf.hooks_decnet + hooknum;
304 #ifdef CONFIG_NETFILTER_INGRESS
305 if (hooknum == NF_NETDEV_INGRESS) {
306 if (dev && dev_net(dev) == net)
307 return &dev->nf_hooks_ingress;
314 static int __nf_register_net_hook(struct net *net, int pf,
315 const struct nf_hook_ops *reg)
317 struct nf_hook_entries *p, *new_hooks;
318 struct nf_hook_entries __rcu **pp;
320 if (pf == NFPROTO_NETDEV) {
321 #ifndef CONFIG_NETFILTER_INGRESS
322 if (reg->hooknum == NF_NETDEV_INGRESS)
325 if (reg->hooknum != NF_NETDEV_INGRESS ||
326 !reg->dev || dev_net(reg->dev) != net)
330 pp = nf_hook_entry_head(net, pf, reg->hooknum, reg->dev);
334 mutex_lock(&nf_hook_mutex);
336 p = nf_entry_dereference(*pp);
337 new_hooks = nf_hook_entries_grow(p, reg);
339 if (!IS_ERR(new_hooks))
340 rcu_assign_pointer(*pp, new_hooks);
342 mutex_unlock(&nf_hook_mutex);
343 if (IS_ERR(new_hooks))
344 return PTR_ERR(new_hooks);
346 hooks_validate(new_hooks);
347 #ifdef CONFIG_NETFILTER_INGRESS
348 if (pf == NFPROTO_NETDEV && reg->hooknum == NF_NETDEV_INGRESS)
349 net_inc_ingress_queue();
351 #ifdef CONFIG_JUMP_LABEL
352 static_key_slow_inc(&nf_hooks_needed[pf][reg->hooknum]);
354 BUG_ON(p == new_hooks);
355 nf_hook_entries_free(p);
360 * nf_remove_net_hook - remove a hook from blob
362 * @oldp: current address of hook blob
363 * @unreg: hook to unregister
365 * This cannot fail, hook unregistration must always succeed.
366 * Therefore replace the to-be-removed hook with a dummy hook.
368 static bool nf_remove_net_hook(struct nf_hook_entries *old,
369 const struct nf_hook_ops *unreg)
371 struct nf_hook_ops **orig_ops;
374 orig_ops = nf_hook_entries_get_hook_ops(old);
375 for (i = 0; i < old->num_hook_entries; i++) {
376 if (orig_ops[i] != unreg)
378 WRITE_ONCE(old->hooks[i].hook, accept_all);
379 WRITE_ONCE(orig_ops[i], &dummy_ops);
386 static void __nf_unregister_net_hook(struct net *net, int pf,
387 const struct nf_hook_ops *reg)
389 struct nf_hook_entries __rcu **pp;
390 struct nf_hook_entries *p;
392 pp = nf_hook_entry_head(net, pf, reg->hooknum, reg->dev);
396 mutex_lock(&nf_hook_mutex);
398 p = nf_entry_dereference(*pp);
399 if (WARN_ON_ONCE(!p)) {
400 mutex_unlock(&nf_hook_mutex);
404 if (nf_remove_net_hook(p, reg)) {
405 #ifdef CONFIG_NETFILTER_INGRESS
406 if (pf == NFPROTO_NETDEV && reg->hooknum == NF_NETDEV_INGRESS)
407 net_dec_ingress_queue();
409 #ifdef CONFIG_JUMP_LABEL
410 static_key_slow_dec(&nf_hooks_needed[pf][reg->hooknum]);
413 WARN_ONCE(1, "hook not found, pf %d num %d", pf, reg->hooknum);
416 p = __nf_hook_entries_try_shrink(p, pp);
417 mutex_unlock(&nf_hook_mutex);
421 nf_queue_nf_hook_drop(net);
422 nf_hook_entries_free(p);
425 void nf_unregister_net_hook(struct net *net, const struct nf_hook_ops *reg)
427 if (reg->pf == NFPROTO_INET) {
428 __nf_unregister_net_hook(net, NFPROTO_IPV4, reg);
429 __nf_unregister_net_hook(net, NFPROTO_IPV6, reg);
431 __nf_unregister_net_hook(net, reg->pf, reg);
434 EXPORT_SYMBOL(nf_unregister_net_hook);
436 void nf_hook_entries_delete_raw(struct nf_hook_entries __rcu **pp,
437 const struct nf_hook_ops *reg)
439 struct nf_hook_entries *p;
441 p = rcu_dereference_raw(*pp);
442 if (nf_remove_net_hook(p, reg)) {
443 p = __nf_hook_entries_try_shrink(p, pp);
444 nf_hook_entries_free(p);
447 EXPORT_SYMBOL_GPL(nf_hook_entries_delete_raw);
449 int nf_register_net_hook(struct net *net, const struct nf_hook_ops *reg)
453 if (reg->pf == NFPROTO_INET) {
454 err = __nf_register_net_hook(net, NFPROTO_IPV4, reg);
458 err = __nf_register_net_hook(net, NFPROTO_IPV6, reg);
460 __nf_unregister_net_hook(net, NFPROTO_IPV4, reg);
464 err = __nf_register_net_hook(net, reg->pf, reg);
471 EXPORT_SYMBOL(nf_register_net_hook);
473 int nf_register_net_hooks(struct net *net, const struct nf_hook_ops *reg,
479 for (i = 0; i < n; i++) {
480 err = nf_register_net_hook(net, ®[i]);
488 nf_unregister_net_hooks(net, reg, i);
491 EXPORT_SYMBOL(nf_register_net_hooks);
493 void nf_unregister_net_hooks(struct net *net, const struct nf_hook_ops *reg,
494 unsigned int hookcount)
498 for (i = 0; i < hookcount; i++)
499 nf_unregister_net_hook(net, ®[i]);
501 EXPORT_SYMBOL(nf_unregister_net_hooks);
503 /* Returns 1 if okfn() needs to be executed by the caller,
504 * -EPERM for NF_DROP, 0 otherwise. Caller must hold rcu_read_lock. */
505 int nf_hook_slow(struct sk_buff *skb, struct nf_hook_state *state,
506 const struct nf_hook_entries *e, unsigned int s)
508 unsigned int verdict;
511 for (; s < e->num_hook_entries; s++) {
512 verdict = nf_hook_entry_hookfn(&e->hooks[s], skb, state);
513 switch (verdict & NF_VERDICT_MASK) {
518 ret = NF_DROP_GETERR(verdict);
523 ret = nf_queue(skb, state, e, s, verdict);
528 /* Implicit handling for NF_STOLEN, as well as any other
529 * non conventional verdicts.
537 EXPORT_SYMBOL(nf_hook_slow);
540 int skb_make_writable(struct sk_buff *skb, unsigned int writable_len)
542 if (writable_len > skb->len)
545 /* Not exclusive use of packet? Must copy. */
546 if (!skb_cloned(skb)) {
547 if (writable_len <= skb_headlen(skb))
549 } else if (skb_clone_writable(skb, writable_len))
552 if (writable_len <= skb_headlen(skb))
555 writable_len -= skb_headlen(skb);
557 return !!__pskb_pull_tail(skb, writable_len);
559 EXPORT_SYMBOL(skb_make_writable);
561 /* This needs to be compiled in any case to avoid dependencies between the
562 * nfnetlink_queue code and nf_conntrack.
564 struct nfnl_ct_hook __rcu *nfnl_ct_hook __read_mostly;
565 EXPORT_SYMBOL_GPL(nfnl_ct_hook);
567 struct nf_ct_hook __rcu *nf_ct_hook __read_mostly;
568 EXPORT_SYMBOL_GPL(nf_ct_hook);
570 #if IS_ENABLED(CONFIG_NF_CONNTRACK)
571 /* This does not belong here, but locally generated errors need it if connection
572 tracking in use: without this, connection may not be in hash table, and hence
573 manufactured ICMP or RST packets will not be associated with it. */
574 void (*ip_ct_attach)(struct sk_buff *, const struct sk_buff *)
576 EXPORT_SYMBOL(ip_ct_attach);
578 struct nf_nat_hook __rcu *nf_nat_hook __read_mostly;
579 EXPORT_SYMBOL_GPL(nf_nat_hook);
581 void nf_ct_attach(struct sk_buff *new, const struct sk_buff *skb)
583 void (*attach)(struct sk_buff *, const struct sk_buff *);
587 attach = rcu_dereference(ip_ct_attach);
593 EXPORT_SYMBOL(nf_ct_attach);
595 void nf_conntrack_destroy(struct nf_conntrack *nfct)
597 struct nf_ct_hook *ct_hook;
600 ct_hook = rcu_dereference(nf_ct_hook);
601 BUG_ON(ct_hook == NULL);
602 ct_hook->destroy(nfct);
605 EXPORT_SYMBOL(nf_conntrack_destroy);
607 bool nf_ct_get_tuple_skb(struct nf_conntrack_tuple *dst_tuple,
608 const struct sk_buff *skb)
610 struct nf_ct_hook *ct_hook;
614 ct_hook = rcu_dereference(nf_ct_hook);
616 ret = ct_hook->get_tuple_skb(dst_tuple, skb);
620 EXPORT_SYMBOL(nf_ct_get_tuple_skb);
622 /* Built-in default zone used e.g. by modules. */
623 const struct nf_conntrack_zone nf_ct_zone_dflt = {
624 .id = NF_CT_DEFAULT_ZONE_ID,
625 .dir = NF_CT_DEFAULT_ZONE_DIR,
627 EXPORT_SYMBOL_GPL(nf_ct_zone_dflt);
628 #endif /* CONFIG_NF_CONNTRACK */
630 static void __net_init
631 __netfilter_net_init(struct nf_hook_entries __rcu **e, int max)
635 for (h = 0; h < max; h++)
636 RCU_INIT_POINTER(e[h], NULL);
639 static int __net_init netfilter_net_init(struct net *net)
641 __netfilter_net_init(net->nf.hooks_ipv4, ARRAY_SIZE(net->nf.hooks_ipv4));
642 __netfilter_net_init(net->nf.hooks_ipv6, ARRAY_SIZE(net->nf.hooks_ipv6));
643 #ifdef CONFIG_NETFILTER_FAMILY_ARP
644 __netfilter_net_init(net->nf.hooks_arp, ARRAY_SIZE(net->nf.hooks_arp));
646 #ifdef CONFIG_NETFILTER_FAMILY_BRIDGE
647 __netfilter_net_init(net->nf.hooks_bridge, ARRAY_SIZE(net->nf.hooks_bridge));
649 #if IS_ENABLED(CONFIG_DECNET)
650 __netfilter_net_init(net->nf.hooks_decnet, ARRAY_SIZE(net->nf.hooks_decnet));
653 #ifdef CONFIG_PROC_FS
654 net->nf.proc_netfilter = proc_net_mkdir(net, "netfilter",
656 if (!net->nf.proc_netfilter) {
657 if (!net_eq(net, &init_net))
658 pr_err("cannot create netfilter proc entry");
667 static void __net_exit netfilter_net_exit(struct net *net)
669 remove_proc_entry("netfilter", net->proc_net);
672 static struct pernet_operations netfilter_net_ops = {
673 .init = netfilter_net_init,
674 .exit = netfilter_net_exit,
677 int __init netfilter_init(void)
681 ret = register_pernet_subsys(&netfilter_net_ops);
685 ret = netfilter_log_init();
691 unregister_pernet_subsys(&netfilter_net_ops);