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>
24 #include "nf_internals.h"
26 static DEFINE_MUTEX(afinfo_mutex
);
28 struct nf_afinfo
*nf_afinfo
[NPROTO
] __read_mostly
;
29 EXPORT_SYMBOL(nf_afinfo
);
31 int nf_register_afinfo(struct nf_afinfo
*afinfo
)
35 err
= mutex_lock_interruptible(&afinfo_mutex
);
38 rcu_assign_pointer(nf_afinfo
[afinfo
->family
], afinfo
);
39 mutex_unlock(&afinfo_mutex
);
42 EXPORT_SYMBOL_GPL(nf_register_afinfo
);
44 void nf_unregister_afinfo(struct nf_afinfo
*afinfo
)
46 mutex_lock(&afinfo_mutex
);
47 rcu_assign_pointer(nf_afinfo
[afinfo
->family
], NULL
);
48 mutex_unlock(&afinfo_mutex
);
51 EXPORT_SYMBOL_GPL(nf_unregister_afinfo
);
53 /* In this code, we can be waiting indefinitely for userspace to
54 * service a packet if a hook returns NF_QUEUE. We could keep a count
55 * of skbuffs queued for userspace, and not deregister a hook unless
56 * this is zero, but that sucks. Now, we simply check when the
57 * packets come back: if the hook is gone, the packet is discarded. */
58 struct list_head nf_hooks
[NPROTO
][NF_MAX_HOOKS
] __read_mostly
;
59 EXPORT_SYMBOL(nf_hooks
);
60 static DEFINE_MUTEX(nf_hook_mutex
);
62 int nf_register_hook(struct nf_hook_ops
*reg
)
67 err
= mutex_lock_interruptible(&nf_hook_mutex
);
70 list_for_each(i
, &nf_hooks
[reg
->pf
][reg
->hooknum
]) {
71 if (reg
->priority
< ((struct nf_hook_ops
*)i
)->priority
)
74 list_add_rcu(®
->list
, i
->prev
);
75 mutex_unlock(&nf_hook_mutex
);
78 EXPORT_SYMBOL(nf_register_hook
);
80 void nf_unregister_hook(struct nf_hook_ops
*reg
)
82 mutex_lock(&nf_hook_mutex
);
83 list_del_rcu(®
->list
);
84 mutex_unlock(&nf_hook_mutex
);
88 EXPORT_SYMBOL(nf_unregister_hook
);
90 int nf_register_hooks(struct nf_hook_ops
*reg
, unsigned int n
)
95 for (i
= 0; i
< n
; i
++) {
96 err
= nf_register_hook(®
[i
]);
104 nf_unregister_hooks(reg
, i
);
107 EXPORT_SYMBOL(nf_register_hooks
);
109 void nf_unregister_hooks(struct nf_hook_ops
*reg
, unsigned int n
)
113 for (i
= 0; i
< n
; i
++)
114 nf_unregister_hook(®
[i
]);
116 EXPORT_SYMBOL(nf_unregister_hooks
);
118 unsigned int nf_iterate(struct list_head
*head
,
119 struct sk_buff
**skb
,
121 const struct net_device
*indev
,
122 const struct net_device
*outdev
,
123 struct list_head
**i
,
124 int (*okfn
)(struct sk_buff
*),
127 unsigned int verdict
;
130 * The caller must not block between calls to this
131 * function because of risk of continuing from deleted element.
133 list_for_each_continue_rcu(*i
, head
) {
134 struct nf_hook_ops
*elem
= (struct nf_hook_ops
*)*i
;
136 if (hook_thresh
> elem
->priority
)
139 /* Optimization: we don't need to hold module
140 reference here, since function can't sleep. --RR */
141 verdict
= elem
->hook(hook
, skb
, indev
, outdev
, okfn
);
142 if (verdict
!= NF_ACCEPT
) {
143 #ifdef CONFIG_NETFILTER_DEBUG
144 if (unlikely((verdict
& NF_VERDICT_MASK
)
146 NFDEBUG("Evil return from %p(%u).\n",
151 if (verdict
!= NF_REPEAT
)
160 /* Returns 1 if okfn() needs to be executed by the caller,
161 * -EPERM for NF_DROP, 0 otherwise. */
162 int nf_hook_slow(int pf
, unsigned int hook
, struct sk_buff
**pskb
,
163 struct net_device
*indev
,
164 struct net_device
*outdev
,
165 int (*okfn
)(struct sk_buff
*),
168 struct list_head
*elem
;
169 unsigned int verdict
;
172 /* We may already have this, but read-locks nest anyway */
175 elem
= &nf_hooks
[pf
][hook
];
177 verdict
= nf_iterate(&nf_hooks
[pf
][hook
], pskb
, hook
, indev
,
178 outdev
, &elem
, okfn
, hook_thresh
);
179 if (verdict
== NF_ACCEPT
|| verdict
== NF_STOP
) {
182 } else if (verdict
== NF_DROP
) {
185 } else if ((verdict
& NF_VERDICT_MASK
) == NF_QUEUE
) {
186 NFDEBUG("nf_hook: Verdict = QUEUE.\n");
187 if (!nf_queue(*pskb
, elem
, pf
, hook
, indev
, outdev
, okfn
,
188 verdict
>> NF_VERDICT_BITS
))
195 EXPORT_SYMBOL(nf_hook_slow
);
198 int skb_make_writable(struct sk_buff
**pskb
, unsigned int writable_len
)
200 struct sk_buff
*nskb
;
202 if (writable_len
> (*pskb
)->len
)
205 /* Not exclusive use of packet? Must copy. */
206 if (skb_cloned(*pskb
) && !skb_clone_writable(*pskb
, writable_len
))
208 if (skb_shared(*pskb
))
211 return pskb_may_pull(*pskb
, writable_len
);
214 nskb
= skb_copy(*pskb
, GFP_ATOMIC
);
217 BUG_ON(skb_is_nonlinear(nskb
));
219 /* Rest of kernel will get very unhappy if we pass it a
220 suddenly-orphaned skbuff */
222 skb_set_owner_w(nskb
, (*pskb
)->sk
);
227 EXPORT_SYMBOL(skb_make_writable
);
229 void nf_proto_csum_replace4(__sum16
*sum
, struct sk_buff
*skb
,
230 __be32 from
, __be32 to
, int pseudohdr
)
232 __be32 diff
[] = { ~from
, to
};
233 if (skb
->ip_summed
!= CHECKSUM_PARTIAL
) {
234 *sum
= csum_fold(csum_partial(diff
, sizeof(diff
),
235 ~csum_unfold(*sum
)));
236 if (skb
->ip_summed
== CHECKSUM_COMPLETE
&& pseudohdr
)
237 skb
->csum
= ~csum_partial(diff
, sizeof(diff
),
239 } else if (pseudohdr
)
240 *sum
= ~csum_fold(csum_partial(diff
, sizeof(diff
),
243 EXPORT_SYMBOL(nf_proto_csum_replace4
);
245 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
246 /* This does not belong here, but locally generated errors need it if connection
247 tracking in use: without this, connection may not be in hash table, and hence
248 manufactured ICMP or RST packets will not be associated with it. */
249 void (*ip_ct_attach
)(struct sk_buff
*, struct sk_buff
*);
250 EXPORT_SYMBOL(ip_ct_attach
);
252 void nf_ct_attach(struct sk_buff
*new, struct sk_buff
*skb
)
254 void (*attach
)(struct sk_buff
*, struct sk_buff
*);
258 attach
= rcu_dereference(ip_ct_attach
);
264 EXPORT_SYMBOL(nf_ct_attach
);
266 void (*nf_ct_destroy
)(struct nf_conntrack
*);
267 EXPORT_SYMBOL(nf_ct_destroy
);
269 void nf_conntrack_destroy(struct nf_conntrack
*nfct
)
271 void (*destroy
)(struct nf_conntrack
*);
274 destroy
= rcu_dereference(nf_ct_destroy
);
275 BUG_ON(destroy
== NULL
);
279 EXPORT_SYMBOL(nf_conntrack_destroy
);
280 #endif /* CONFIG_NF_CONNTRACK */
282 #ifdef CONFIG_PROC_FS
283 struct proc_dir_entry
*proc_net_netfilter
;
284 EXPORT_SYMBOL(proc_net_netfilter
);
287 void __init
netfilter_init(void)
290 for (i
= 0; i
< NPROTO
; i
++) {
291 for (h
= 0; h
< NF_MAX_HOOKS
; h
++)
292 INIT_LIST_HEAD(&nf_hooks
[i
][h
]);
295 #ifdef CONFIG_PROC_FS
296 proc_net_netfilter
= proc_mkdir("netfilter", proc_net
);
297 if (!proc_net_netfilter
)
298 panic("cannot create netfilter proc entry");
301 if (netfilter_queue_init() < 0)
302 panic("cannot initialize nf_queue");
303 if (netfilter_log_init() < 0)
304 panic("cannot initialize nf_log");