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.
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/inetdevice.h>
20 #include <linux/proc_fs.h>
21 #include <linux/mutex.h>
22 #include <linux/slab.h>
23 #include <net/net_namespace.h>
26 #include "nf_internals.h"
28 static DEFINE_MUTEX(afinfo_mutex);
30 const struct nf_afinfo __rcu *nf_afinfo[NFPROTO_NUMPROTO] __read_mostly;
31 EXPORT_SYMBOL(nf_afinfo);
33 int nf_register_afinfo(const struct nf_afinfo *afinfo)
37 err = mutex_lock_interruptible(&afinfo_mutex);
40 rcu_assign_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_assign_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);
57 static DEFINE_MUTEX(nf_hook_mutex);
59 int nf_register_hook(struct nf_hook_ops *reg)
61 struct nf_hook_ops *elem;
64 err = mutex_lock_interruptible(&nf_hook_mutex);
67 list_for_each_entry(elem, &nf_hooks[reg->pf][reg->hooknum], list) {
68 if (reg->priority < elem->priority)
71 list_add_rcu(®->list, elem->list.prev);
72 mutex_unlock(&nf_hook_mutex);
75 EXPORT_SYMBOL(nf_register_hook);
77 void nf_unregister_hook(struct nf_hook_ops *reg)
79 mutex_lock(&nf_hook_mutex);
80 list_del_rcu(®->list);
81 mutex_unlock(&nf_hook_mutex);
85 EXPORT_SYMBOL(nf_unregister_hook);
87 int nf_register_hooks(struct nf_hook_ops *reg, unsigned int n)
92 for (i = 0; i < n; i++) {
93 err = nf_register_hook(®[i]);
101 nf_unregister_hooks(reg, i);
104 EXPORT_SYMBOL(nf_register_hooks);
106 void nf_unregister_hooks(struct nf_hook_ops *reg, unsigned int n)
109 nf_unregister_hook(®[n]);
111 EXPORT_SYMBOL(nf_unregister_hooks);
113 unsigned int nf_iterate(struct list_head *head,
116 const struct net_device *indev,
117 const struct net_device *outdev,
118 struct list_head **i,
119 int (*okfn)(struct sk_buff *),
122 unsigned int verdict;
125 * The caller must not block between calls to this
126 * function because of risk of continuing from deleted element.
128 list_for_each_continue_rcu(*i, head) {
129 struct nf_hook_ops *elem = (struct nf_hook_ops *)*i;
131 if (hook_thresh > elem->priority)
134 /* Optimization: we don't need to hold module
135 reference here, since function can't sleep. --RR */
137 verdict = elem->hook(hook, skb, indev, outdev, okfn);
138 if (verdict != NF_ACCEPT) {
139 #ifdef CONFIG_NETFILTER_DEBUG
140 if (unlikely((verdict & NF_VERDICT_MASK)
142 NFDEBUG("Evil return from %p(%u).\n",
147 if (verdict != NF_REPEAT)
156 /* Returns 1 if okfn() needs to be executed by the caller,
157 * -EPERM for NF_DROP, 0 otherwise. */
158 int nf_hook_slow(u_int8_t pf, unsigned int hook, struct sk_buff *skb,
159 struct net_device *indev,
160 struct net_device *outdev,
161 int (*okfn)(struct sk_buff *),
164 struct list_head *elem;
165 unsigned int verdict;
168 /* We may already have this, but read-locks nest anyway */
171 elem = &nf_hooks[pf][hook];
173 verdict = nf_iterate(&nf_hooks[pf][hook], skb, hook, indev,
174 outdev, &elem, okfn, hook_thresh);
175 if (verdict == NF_ACCEPT || verdict == NF_STOP) {
177 } else if ((verdict & NF_VERDICT_MASK) == NF_DROP) {
179 ret = NF_DROP_GETERR(verdict);
182 } else if ((verdict & NF_VERDICT_MASK) == NF_QUEUE) {
183 ret = nf_queue(skb, elem, pf, hook, indev, outdev, okfn,
184 verdict >> NF_VERDICT_QBITS);
186 if (ret == -ECANCELED)
189 (verdict & NF_VERDICT_FLAG_QUEUE_BYPASS))
198 EXPORT_SYMBOL(nf_hook_slow);
201 int skb_make_writable(struct sk_buff *skb, unsigned int writable_len)
203 if (writable_len > skb->len)
206 /* Not exclusive use of packet? Must copy. */
207 if (!skb_cloned(skb)) {
208 if (writable_len <= skb_headlen(skb))
210 } else if (skb_clone_writable(skb, writable_len))
213 if (writable_len <= skb_headlen(skb))
216 writable_len -= skb_headlen(skb);
218 return !!__pskb_pull_tail(skb, writable_len);
220 EXPORT_SYMBOL(skb_make_writable);
222 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
223 /* This does not belong here, but locally generated errors need it if connection
224 tracking in use: without this, connection may not be in hash table, and hence
225 manufactured ICMP or RST packets will not be associated with it. */
226 void (*ip_ct_attach)(struct sk_buff *, struct sk_buff *) __rcu __read_mostly;
227 EXPORT_SYMBOL(ip_ct_attach);
229 void nf_ct_attach(struct sk_buff *new, struct sk_buff *skb)
231 void (*attach)(struct sk_buff *, struct sk_buff *);
235 attach = rcu_dereference(ip_ct_attach);
241 EXPORT_SYMBOL(nf_ct_attach);
243 void (*nf_ct_destroy)(struct nf_conntrack *) __rcu __read_mostly;
244 EXPORT_SYMBOL(nf_ct_destroy);
246 void nf_conntrack_destroy(struct nf_conntrack *nfct)
248 void (*destroy)(struct nf_conntrack *);
251 destroy = rcu_dereference(nf_ct_destroy);
252 BUG_ON(destroy == NULL);
256 EXPORT_SYMBOL(nf_conntrack_destroy);
257 #endif /* CONFIG_NF_CONNTRACK */
259 #ifdef CONFIG_PROC_FS
260 struct proc_dir_entry *proc_net_netfilter;
261 EXPORT_SYMBOL(proc_net_netfilter);
264 void __init netfilter_init(void)
267 for (i = 0; i < ARRAY_SIZE(nf_hooks); i++) {
268 for (h = 0; h < NF_MAX_HOOKS; h++)
269 INIT_LIST_HEAD(&nf_hooks[i][h]);
272 #ifdef CONFIG_PROC_FS
273 proc_net_netfilter = proc_mkdir("netfilter", init_net.proc_net);
274 if (!proc_net_netfilter)
275 panic("cannot create netfilter proc entry");
278 if (netfilter_queue_init() < 0)
279 panic("cannot initialize nf_queue");
280 if (netfilter_log_init() < 0)
281 panic("cannot initialize nf_log");
285 struct ctl_path nf_net_netfilter_sysctl_path[] = {
286 { .procname = "net", },
287 { .procname = "netfilter", },
290 EXPORT_SYMBOL_GPL(nf_net_netfilter_sysctl_path);
291 #endif /* CONFIG_SYSCTL */