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 * February 2000: Modified by James Morris to have 1 queue per protocol.
10 * 15-Mar-2000: Added NF_REPEAT --RR.
11 * 08-May-2003: Internal logging interface added by Jozsef Kadlecsik.
13 #include <linux/kernel.h>
14 #include <linux/netfilter.h>
15 #include <net/protocol.h>
16 #include <linux/init.h>
17 #include <linux/skbuff.h>
18 #include <linux/wait.h>
19 #include <linux/module.h>
20 #include <linux/interrupt.h>
22 #include <linux/netdevice.h>
23 #include <linux/inetdevice.h>
24 #include <linux/proc_fs.h>
25 #include <linux/mutex.h>
28 #include "nf_internals.h"
30 static DEFINE_MUTEX(afinfo_mutex);
32 struct nf_afinfo *nf_afinfo[NPROTO] __read_mostly;
33 EXPORT_SYMBOL(nf_afinfo);
35 int nf_register_afinfo(struct nf_afinfo *afinfo)
39 err = mutex_lock_interruptible(&afinfo_mutex);
42 rcu_assign_pointer(nf_afinfo[afinfo->family], afinfo);
43 mutex_unlock(&afinfo_mutex);
46 EXPORT_SYMBOL_GPL(nf_register_afinfo);
48 void nf_unregister_afinfo(struct nf_afinfo *afinfo)
50 mutex_lock(&afinfo_mutex);
51 rcu_assign_pointer(nf_afinfo[afinfo->family], NULL);
52 mutex_unlock(&afinfo_mutex);
55 EXPORT_SYMBOL_GPL(nf_unregister_afinfo);
57 /* In this code, we can be waiting indefinitely for userspace to
58 * service a packet if a hook returns NF_QUEUE. We could keep a count
59 * of skbuffs queued for userspace, and not deregister a hook unless
60 * this is zero, but that sucks. Now, we simply check when the
61 * packets come back: if the hook is gone, the packet is discarded. */
62 struct list_head nf_hooks[NPROTO][NF_MAX_HOOKS] __read_mostly;
63 EXPORT_SYMBOL(nf_hooks);
64 static DEFINE_SPINLOCK(nf_hook_lock);
66 int nf_register_hook(struct nf_hook_ops *reg)
70 spin_lock_bh(&nf_hook_lock);
71 list_for_each(i, &nf_hooks[reg->pf][reg->hooknum]) {
72 if (reg->priority < ((struct nf_hook_ops *)i)->priority)
75 list_add_rcu(®->list, i->prev);
76 spin_unlock_bh(&nf_hook_lock);
79 EXPORT_SYMBOL(nf_register_hook);
81 void nf_unregister_hook(struct nf_hook_ops *reg)
83 spin_lock_bh(&nf_hook_lock);
84 list_del_rcu(®->list);
85 spin_unlock_bh(&nf_hook_lock);
89 EXPORT_SYMBOL(nf_unregister_hook);
91 int nf_register_hooks(struct nf_hook_ops *reg, unsigned int n)
96 for (i = 0; i < n; i++) {
97 err = nf_register_hook(®[i]);
105 nf_unregister_hooks(reg, i);
108 EXPORT_SYMBOL(nf_register_hooks);
110 void nf_unregister_hooks(struct nf_hook_ops *reg, unsigned int n)
114 for (i = 0; i < n; i++)
115 nf_unregister_hook(®[i]);
117 EXPORT_SYMBOL(nf_unregister_hooks);
119 unsigned int nf_iterate(struct list_head *head,
120 struct sk_buff **skb,
122 const struct net_device *indev,
123 const struct net_device *outdev,
124 struct list_head **i,
125 int (*okfn)(struct sk_buff *),
128 unsigned int verdict;
131 * The caller must not block between calls to this
132 * function because of risk of continuing from deleted element.
134 list_for_each_continue_rcu(*i, head) {
135 struct nf_hook_ops *elem = (struct nf_hook_ops *)*i;
137 if (hook_thresh > elem->priority)
140 /* Optimization: we don't need to hold module
141 reference here, since function can't sleep. --RR */
142 verdict = elem->hook(hook, skb, indev, outdev, okfn);
143 if (verdict != NF_ACCEPT) {
144 #ifdef CONFIG_NETFILTER_DEBUG
145 if (unlikely((verdict & NF_VERDICT_MASK)
147 NFDEBUG("Evil return from %p(%u).\n",
152 if (verdict != NF_REPEAT)
161 /* Returns 1 if okfn() needs to be executed by the caller,
162 * -EPERM for NF_DROP, 0 otherwise. */
163 int nf_hook_slow(int pf, unsigned int hook, struct sk_buff **pskb,
164 struct net_device *indev,
165 struct net_device *outdev,
166 int (*okfn)(struct sk_buff *),
169 struct list_head *elem;
170 unsigned int verdict;
173 /* We may already have this, but read-locks nest anyway */
176 elem = &nf_hooks[pf][hook];
178 verdict = nf_iterate(&nf_hooks[pf][hook], pskb, hook, indev,
179 outdev, &elem, okfn, hook_thresh);
180 if (verdict == NF_ACCEPT || verdict == NF_STOP) {
183 } else if (verdict == NF_DROP) {
186 } else if ((verdict & NF_VERDICT_MASK) == NF_QUEUE) {
187 NFDEBUG("nf_hook: Verdict = QUEUE.\n");
188 if (!nf_queue(*pskb, elem, pf, hook, indev, outdev, okfn,
189 verdict >> NF_VERDICT_BITS))
196 EXPORT_SYMBOL(nf_hook_slow);
199 int skb_make_writable(struct sk_buff **pskb, unsigned int writable_len)
201 struct sk_buff *nskb;
203 if (writable_len > (*pskb)->len)
206 /* Not exclusive use of packet? Must copy. */
207 if (skb_shared(*pskb) || skb_cloned(*pskb))
210 return pskb_may_pull(*pskb, writable_len);
213 nskb = skb_copy(*pskb, GFP_ATOMIC);
216 BUG_ON(skb_is_nonlinear(nskb));
218 /* Rest of kernel will get very unhappy if we pass it a
219 suddenly-orphaned skbuff */
221 skb_set_owner_w(nskb, (*pskb)->sk);
226 EXPORT_SYMBOL(skb_make_writable);
228 void nf_proto_csum_replace4(__sum16 *sum, struct sk_buff *skb,
229 __be32 from, __be32 to, int pseudohdr)
231 __be32 diff[] = { ~from, to };
232 if (skb->ip_summed != CHECKSUM_PARTIAL) {
233 *sum = csum_fold(csum_partial((char *)diff, sizeof(diff),
234 ~csum_unfold(*sum)));
235 if (skb->ip_summed == CHECKSUM_COMPLETE && pseudohdr)
236 skb->csum = ~csum_partial((char *)diff, sizeof(diff),
238 } else if (pseudohdr)
239 *sum = ~csum_fold(csum_partial((char *)diff, sizeof(diff),
242 EXPORT_SYMBOL(nf_proto_csum_replace4);
244 /* This does not belong here, but locally generated errors need it if connection
245 tracking in use: without this, connection may not be in hash table, and hence
246 manufactured ICMP or RST packets will not be associated with it. */
247 void (*ip_ct_attach)(struct sk_buff *, struct sk_buff *);
248 EXPORT_SYMBOL(ip_ct_attach);
250 void nf_ct_attach(struct sk_buff *new, struct sk_buff *skb)
252 void (*attach)(struct sk_buff *, struct sk_buff *);
256 attach = rcu_dereference(ip_ct_attach);
262 EXPORT_SYMBOL(nf_ct_attach);
264 #ifdef CONFIG_PROC_FS
265 struct proc_dir_entry *proc_net_netfilter;
266 EXPORT_SYMBOL(proc_net_netfilter);
269 void __init netfilter_init(void)
272 for (i = 0; i < NPROTO; i++) {
273 for (h = 0; h < NF_MAX_HOOKS; h++)
274 INIT_LIST_HEAD(&nf_hooks[i][h]);
277 #ifdef CONFIG_PROC_FS
278 proc_net_netfilter = proc_mkdir("netfilter", proc_net);
279 if (!proc_net_netfilter)
280 panic("cannot create netfilter proc entry");
283 if (netfilter_queue_init() < 0)
284 panic("cannot initialize nf_queue");
285 if (netfilter_log_init() < 0)
286 panic("cannot initialize nf_log");