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 <net/net_namespace.h>
25 #include "nf_internals.h"
27 static DEFINE_MUTEX(afinfo_mutex
);
29 struct nf_afinfo
*nf_afinfo
[NPROTO
] __read_mostly
;
30 EXPORT_SYMBOL(nf_afinfo
);
32 int nf_register_afinfo(struct nf_afinfo
*afinfo
)
36 err
= mutex_lock_interruptible(&afinfo_mutex
);
39 rcu_assign_pointer(nf_afinfo
[afinfo
->family
], afinfo
);
40 mutex_unlock(&afinfo_mutex
);
43 EXPORT_SYMBOL_GPL(nf_register_afinfo
);
45 void nf_unregister_afinfo(struct nf_afinfo
*afinfo
)
47 mutex_lock(&afinfo_mutex
);
48 rcu_assign_pointer(nf_afinfo
[afinfo
->family
], NULL
);
49 mutex_unlock(&afinfo_mutex
);
52 EXPORT_SYMBOL_GPL(nf_unregister_afinfo
);
54 /* In this code, we can be waiting indefinitely for userspace to
55 * service a packet if a hook returns NF_QUEUE. We could keep a count
56 * of skbuffs queued for userspace, and not deregister a hook unless
57 * this is zero, but that sucks. Now, we simply check when the
58 * packets come back: if the hook is gone, the packet is discarded. */
59 struct list_head nf_hooks
[NPROTO
][NF_MAX_HOOKS
] __read_mostly
;
60 EXPORT_SYMBOL(nf_hooks
);
61 static DEFINE_MUTEX(nf_hook_mutex
);
63 int nf_register_hook(struct nf_hook_ops
*reg
)
68 err
= mutex_lock_interruptible(&nf_hook_mutex
);
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 mutex_unlock(&nf_hook_mutex
);
79 EXPORT_SYMBOL(nf_register_hook
);
81 void nf_unregister_hook(struct nf_hook_ops
*reg
)
83 mutex_lock(&nf_hook_mutex
);
84 list_del_rcu(®
->list
);
85 mutex_unlock(&nf_hook_mutex
);
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
,
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
*skb
,
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
], skb
, 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(skb
, 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
*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 void nf_proto_csum_replace4(__sum16
*sum
, struct sk_buff
*skb
,
221 __be32 from
, __be32 to
, int pseudohdr
)
223 __be32 diff
[] = { ~from
, to
};
224 if (skb
->ip_summed
!= CHECKSUM_PARTIAL
) {
225 *sum
= csum_fold(csum_partial(diff
, sizeof(diff
),
226 ~csum_unfold(*sum
)));
227 if (skb
->ip_summed
== CHECKSUM_COMPLETE
&& pseudohdr
)
228 skb
->csum
= ~csum_partial(diff
, sizeof(diff
),
230 } else if (pseudohdr
)
231 *sum
= ~csum_fold(csum_partial(diff
, sizeof(diff
),
234 EXPORT_SYMBOL(nf_proto_csum_replace4
);
236 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
237 /* This does not belong here, but locally generated errors need it if connection
238 tracking in use: without this, connection may not be in hash table, and hence
239 manufactured ICMP or RST packets will not be associated with it. */
240 void (*ip_ct_attach
)(struct sk_buff
*, struct sk_buff
*);
241 EXPORT_SYMBOL(ip_ct_attach
);
243 void nf_ct_attach(struct sk_buff
*new, struct sk_buff
*skb
)
245 void (*attach
)(struct sk_buff
*, struct sk_buff
*);
249 attach
= rcu_dereference(ip_ct_attach
);
255 EXPORT_SYMBOL(nf_ct_attach
);
257 void (*nf_ct_destroy
)(struct nf_conntrack
*);
258 EXPORT_SYMBOL(nf_ct_destroy
);
260 void nf_conntrack_destroy(struct nf_conntrack
*nfct
)
262 void (*destroy
)(struct nf_conntrack
*);
265 destroy
= rcu_dereference(nf_ct_destroy
);
266 BUG_ON(destroy
== NULL
);
270 EXPORT_SYMBOL(nf_conntrack_destroy
);
271 #endif /* CONFIG_NF_CONNTRACK */
273 #ifdef CONFIG_PROC_FS
274 struct proc_dir_entry
*proc_net_netfilter
;
275 EXPORT_SYMBOL(proc_net_netfilter
);
278 void __init
netfilter_init(void)
281 for (i
= 0; i
< NPROTO
; i
++) {
282 for (h
= 0; h
< NF_MAX_HOOKS
; h
++)
283 INIT_LIST_HEAD(&nf_hooks
[i
][h
]);
286 #ifdef CONFIG_PROC_FS
287 proc_net_netfilter
= proc_mkdir("netfilter", init_net
.proc_net
);
288 if (!proc_net_netfilter
)
289 panic("cannot create netfilter proc entry");
292 if (netfilter_queue_init() < 0)
293 panic("cannot initialize nf_queue");
294 if (netfilter_log_init() < 0)
295 panic("cannot initialize nf_log");