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_MUTEX(nf_hook_mutex
);
66 int nf_register_hook(struct nf_hook_ops
*reg
)
71 err
= mutex_lock_interruptible(&nf_hook_mutex
);
74 list_for_each(i
, &nf_hooks
[reg
->pf
][reg
->hooknum
]) {
75 if (reg
->priority
< ((struct nf_hook_ops
*)i
)->priority
)
78 list_add_rcu(®
->list
, i
->prev
);
79 mutex_unlock(&nf_hook_mutex
);
82 EXPORT_SYMBOL(nf_register_hook
);
84 void nf_unregister_hook(struct nf_hook_ops
*reg
)
86 mutex_lock(&nf_hook_mutex
);
87 list_del_rcu(®
->list
);
88 mutex_unlock(&nf_hook_mutex
);
92 EXPORT_SYMBOL(nf_unregister_hook
);
94 int nf_register_hooks(struct nf_hook_ops
*reg
, unsigned int n
)
99 for (i
= 0; i
< n
; i
++) {
100 err
= nf_register_hook(®
[i
]);
108 nf_unregister_hooks(reg
, i
);
111 EXPORT_SYMBOL(nf_register_hooks
);
113 void nf_unregister_hooks(struct nf_hook_ops
*reg
, unsigned int n
)
117 for (i
= 0; i
< n
; i
++)
118 nf_unregister_hook(®
[i
]);
120 EXPORT_SYMBOL(nf_unregister_hooks
);
122 unsigned int nf_iterate(struct list_head
*head
,
123 struct sk_buff
**skb
,
125 const struct net_device
*indev
,
126 const struct net_device
*outdev
,
127 struct list_head
**i
,
128 int (*okfn
)(struct sk_buff
*),
131 unsigned int verdict
;
134 * The caller must not block between calls to this
135 * function because of risk of continuing from deleted element.
137 list_for_each_continue_rcu(*i
, head
) {
138 struct nf_hook_ops
*elem
= (struct nf_hook_ops
*)*i
;
140 if (hook_thresh
> elem
->priority
)
143 /* Optimization: we don't need to hold module
144 reference here, since function can't sleep. --RR */
145 verdict
= elem
->hook(hook
, skb
, indev
, outdev
, okfn
);
146 if (verdict
!= NF_ACCEPT
) {
147 #ifdef CONFIG_NETFILTER_DEBUG
148 if (unlikely((verdict
& NF_VERDICT_MASK
)
150 NFDEBUG("Evil return from %p(%u).\n",
155 if (verdict
!= NF_REPEAT
)
164 /* Returns 1 if okfn() needs to be executed by the caller,
165 * -EPERM for NF_DROP, 0 otherwise. */
166 int nf_hook_slow(int pf
, unsigned int hook
, struct sk_buff
**pskb
,
167 struct net_device
*indev
,
168 struct net_device
*outdev
,
169 int (*okfn
)(struct sk_buff
*),
172 struct list_head
*elem
;
173 unsigned int verdict
;
176 /* We may already have this, but read-locks nest anyway */
179 elem
= &nf_hooks
[pf
][hook
];
181 verdict
= nf_iterate(&nf_hooks
[pf
][hook
], pskb
, hook
, indev
,
182 outdev
, &elem
, okfn
, hook_thresh
);
183 if (verdict
== NF_ACCEPT
|| verdict
== NF_STOP
) {
186 } else if (verdict
== NF_DROP
) {
189 } else if ((verdict
& NF_VERDICT_MASK
) == NF_QUEUE
) {
190 NFDEBUG("nf_hook: Verdict = QUEUE.\n");
191 if (!nf_queue(*pskb
, elem
, pf
, hook
, indev
, outdev
, okfn
,
192 verdict
>> NF_VERDICT_BITS
))
199 EXPORT_SYMBOL(nf_hook_slow
);
202 int skb_make_writable(struct sk_buff
**pskb
, unsigned int writable_len
)
204 struct sk_buff
*nskb
;
206 if (writable_len
> (*pskb
)->len
)
209 /* Not exclusive use of packet? Must copy. */
210 if (skb_shared(*pskb
) || skb_cloned(*pskb
))
213 return pskb_may_pull(*pskb
, writable_len
);
216 nskb
= skb_copy(*pskb
, GFP_ATOMIC
);
219 BUG_ON(skb_is_nonlinear(nskb
));
221 /* Rest of kernel will get very unhappy if we pass it a
222 suddenly-orphaned skbuff */
224 skb_set_owner_w(nskb
, (*pskb
)->sk
);
229 EXPORT_SYMBOL(skb_make_writable
);
231 void nf_proto_csum_replace4(__sum16
*sum
, struct sk_buff
*skb
,
232 __be32 from
, __be32 to
, int pseudohdr
)
234 __be32 diff
[] = { ~from
, to
};
235 if (skb
->ip_summed
!= CHECKSUM_PARTIAL
) {
236 *sum
= csum_fold(csum_partial((char *)diff
, sizeof(diff
),
237 ~csum_unfold(*sum
)));
238 if (skb
->ip_summed
== CHECKSUM_COMPLETE
&& pseudohdr
)
239 skb
->csum
= ~csum_partial((char *)diff
, sizeof(diff
),
241 } else if (pseudohdr
)
242 *sum
= ~csum_fold(csum_partial((char *)diff
, sizeof(diff
),
245 EXPORT_SYMBOL(nf_proto_csum_replace4
);
247 /* This does not belong here, but locally generated errors need it if connection
248 tracking in use: without this, connection may not be in hash table, and hence
249 manufactured ICMP or RST packets will not be associated with it. */
250 void (*ip_ct_attach
)(struct sk_buff
*, struct sk_buff
*);
251 EXPORT_SYMBOL(ip_ct_attach
);
253 void nf_ct_attach(struct sk_buff
*new, struct sk_buff
*skb
)
255 void (*attach
)(struct sk_buff
*, struct sk_buff
*);
259 attach
= rcu_dereference(ip_ct_attach
);
265 EXPORT_SYMBOL(nf_ct_attach
);
267 #ifdef CONFIG_PROC_FS
268 struct proc_dir_entry
*proc_net_netfilter
;
269 EXPORT_SYMBOL(proc_net_netfilter
);
272 void __init
netfilter_init(void)
275 for (i
= 0; i
< NPROTO
; i
++) {
276 for (h
= 0; h
< NF_MAX_HOOKS
; h
++)
277 INIT_LIST_HEAD(&nf_hooks
[i
][h
]);
280 #ifdef CONFIG_PROC_FS
281 proc_net_netfilter
= proc_mkdir("netfilter", proc_net
);
282 if (!proc_net_netfilter
)
283 panic("cannot create netfilter proc entry");
286 if (netfilter_queue_init() < 0)
287 panic("cannot initialize nf_queue");
288 if (netfilter_log_init() < 0)
289 panic("cannot initialize nf_log");