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>
24 #include <linux/slab.h>
25 #include <net/net_namespace.h>
28 #include "nf_internals.h"
30 static DEFINE_MUTEX(afinfo_mutex);
32 const struct nf_afinfo __rcu *nf_afinfo[NFPROTO_NUMPROTO] __read_mostly;
33 EXPORT_SYMBOL(nf_afinfo);
34 const struct nf_ipv6_ops __rcu *nf_ipv6_ops __read_mostly;
35 EXPORT_SYMBOL_GPL(nf_ipv6_ops);
37 int nf_register_afinfo(const struct nf_afinfo *afinfo)
39 mutex_lock(&afinfo_mutex);
40 RCU_INIT_POINTER(nf_afinfo[afinfo->family], afinfo);
41 mutex_unlock(&afinfo_mutex);
44 EXPORT_SYMBOL_GPL(nf_register_afinfo);
46 void nf_unregister_afinfo(const struct nf_afinfo *afinfo)
48 mutex_lock(&afinfo_mutex);
49 RCU_INIT_POINTER(nf_afinfo[afinfo->family], NULL);
50 mutex_unlock(&afinfo_mutex);
53 EXPORT_SYMBOL_GPL(nf_unregister_afinfo);
55 struct list_head nf_hooks[NFPROTO_NUMPROTO][NF_MAX_HOOKS] __read_mostly;
56 EXPORT_SYMBOL(nf_hooks);
58 #ifdef HAVE_JUMP_LABEL
59 struct static_key nf_hooks_needed[NFPROTO_NUMPROTO][NF_MAX_HOOKS];
60 EXPORT_SYMBOL(nf_hooks_needed);
63 static DEFINE_MUTEX(nf_hook_mutex);
65 int nf_register_hook(struct nf_hook_ops *reg)
67 struct nf_hook_ops *elem;
69 mutex_lock(&nf_hook_mutex);
70 list_for_each_entry(elem, &nf_hooks[reg->pf][reg->hooknum], list) {
71 if (reg->priority < elem->priority)
74 list_add_rcu(®->list, elem->list.prev);
75 mutex_unlock(&nf_hook_mutex);
76 #ifdef HAVE_JUMP_LABEL
77 static_key_slow_inc(&nf_hooks_needed[reg->pf][reg->hooknum]);
81 EXPORT_SYMBOL(nf_register_hook);
83 void nf_unregister_hook(struct nf_hook_ops *reg)
85 mutex_lock(&nf_hook_mutex);
86 list_del_rcu(®->list);
87 mutex_unlock(&nf_hook_mutex);
88 #ifdef HAVE_JUMP_LABEL
89 static_key_slow_dec(&nf_hooks_needed[reg->pf][reg->hooknum]);
93 EXPORT_SYMBOL(nf_unregister_hook);
95 int nf_register_hooks(struct nf_hook_ops *reg, unsigned int n)
100 for (i = 0; i < n; i++) {
101 err = nf_register_hook(®[i]);
109 nf_unregister_hooks(reg, i);
112 EXPORT_SYMBOL(nf_register_hooks);
114 void nf_unregister_hooks(struct nf_hook_ops *reg, unsigned int n)
117 nf_unregister_hook(®[n]);
119 EXPORT_SYMBOL(nf_unregister_hooks);
121 unsigned int nf_iterate(struct list_head *head,
123 struct nf_hook_state *state,
124 struct nf_hook_ops **elemp)
126 unsigned int verdict;
129 * The caller must not block between calls to this
130 * function because of risk of continuing from deleted element.
132 list_for_each_entry_continue_rcu((*elemp), head, list) {
133 if (state->thresh > (*elemp)->priority)
136 /* Optimization: we don't need to hold module
137 reference here, since function can't sleep. --RR */
139 verdict = (*elemp)->hook(*elemp, skb, state);
140 if (verdict != NF_ACCEPT) {
141 #ifdef CONFIG_NETFILTER_DEBUG
142 if (unlikely((verdict & NF_VERDICT_MASK)
144 NFDEBUG("Evil return from %p(%u).\n",
145 (*elemp)->hook, state->hook);
149 if (verdict != NF_REPEAT)
158 /* Returns 1 if okfn() needs to be executed by the caller,
159 * -EPERM for NF_DROP, 0 otherwise. */
160 int nf_hook_slow(struct sk_buff *skb, struct nf_hook_state *state)
162 struct nf_hook_ops *elem;
163 unsigned int verdict;
166 /* We may already have this, but read-locks nest anyway */
169 elem = list_entry_rcu(&nf_hooks[state->pf][state->hook],
170 struct nf_hook_ops, list);
172 verdict = nf_iterate(&nf_hooks[state->pf][state->hook], skb, state,
174 if (verdict == NF_ACCEPT || verdict == NF_STOP) {
176 } else if ((verdict & NF_VERDICT_MASK) == NF_DROP) {
178 ret = NF_DROP_GETERR(verdict);
181 } else if ((verdict & NF_VERDICT_MASK) == NF_QUEUE) {
182 int err = nf_queue(skb, elem, state,
183 verdict >> NF_VERDICT_QBITS);
185 if (err == -ECANCELED)
188 (verdict & NF_VERDICT_FLAG_QUEUE_BYPASS))
196 EXPORT_SYMBOL(nf_hook_slow);
199 int skb_make_writable(struct sk_buff *skb, unsigned int writable_len)
201 if (writable_len > skb->len)
204 /* Not exclusive use of packet? Must copy. */
205 if (!skb_cloned(skb)) {
206 if (writable_len <= skb_headlen(skb))
208 } else if (skb_clone_writable(skb, writable_len))
211 if (writable_len <= skb_headlen(skb))
214 writable_len -= skb_headlen(skb);
216 return !!__pskb_pull_tail(skb, writable_len);
218 EXPORT_SYMBOL(skb_make_writable);
220 #if IS_ENABLED(CONFIG_NF_CONNTRACK)
221 /* This does not belong here, but locally generated errors need it if connection
222 tracking in use: without this, connection may not be in hash table, and hence
223 manufactured ICMP or RST packets will not be associated with it. */
224 void (*ip_ct_attach)(struct sk_buff *, const struct sk_buff *)
226 EXPORT_SYMBOL(ip_ct_attach);
228 void nf_ct_attach(struct sk_buff *new, const struct sk_buff *skb)
230 void (*attach)(struct sk_buff *, const struct sk_buff *);
234 attach = rcu_dereference(ip_ct_attach);
240 EXPORT_SYMBOL(nf_ct_attach);
242 void (*nf_ct_destroy)(struct nf_conntrack *) __rcu __read_mostly;
243 EXPORT_SYMBOL(nf_ct_destroy);
245 void nf_conntrack_destroy(struct nf_conntrack *nfct)
247 void (*destroy)(struct nf_conntrack *);
250 destroy = rcu_dereference(nf_ct_destroy);
251 BUG_ON(destroy == NULL);
255 EXPORT_SYMBOL(nf_conntrack_destroy);
257 struct nfq_ct_hook __rcu *nfq_ct_hook __read_mostly;
258 EXPORT_SYMBOL_GPL(nfq_ct_hook);
260 struct nfq_ct_nat_hook __rcu *nfq_ct_nat_hook __read_mostly;
261 EXPORT_SYMBOL_GPL(nfq_ct_nat_hook);
263 #endif /* CONFIG_NF_CONNTRACK */
265 #ifdef CONFIG_NF_NAT_NEEDED
266 void (*nf_nat_decode_session_hook)(struct sk_buff *, struct flowi *);
267 EXPORT_SYMBOL(nf_nat_decode_session_hook);
270 static int __net_init netfilter_net_init(struct net *net)
272 #ifdef CONFIG_PROC_FS
273 net->nf.proc_netfilter = proc_net_mkdir(net, "netfilter",
275 if (!net->nf.proc_netfilter) {
276 if (!net_eq(net, &init_net))
277 pr_err("cannot create netfilter proc entry");
285 static void __net_exit netfilter_net_exit(struct net *net)
287 remove_proc_entry("netfilter", net->proc_net);
290 static struct pernet_operations netfilter_net_ops = {
291 .init = netfilter_net_init,
292 .exit = netfilter_net_exit,
295 int __init netfilter_init(void)
299 for (i = 0; i < ARRAY_SIZE(nf_hooks); i++) {
300 for (h = 0; h < NF_MAX_HOOKS; h++)
301 INIT_LIST_HEAD(&nf_hooks[i][h]);
304 ret = register_pernet_subsys(&netfilter_net_ops);
308 ret = netfilter_log_init();
314 unregister_pernet_subsys(&netfilter_net_ops);