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>
27 #include "nf_internals.h"
29 static DEFINE_SPINLOCK(afinfo_lock
);
31 struct nf_afinfo
*nf_afinfo
[NPROTO
];
32 EXPORT_SYMBOL(nf_afinfo
);
34 int nf_register_afinfo(struct nf_afinfo
*afinfo
)
36 spin_lock(&afinfo_lock
);
37 rcu_assign_pointer(nf_afinfo
[afinfo
->family
], afinfo
);
38 spin_unlock(&afinfo_lock
);
41 EXPORT_SYMBOL_GPL(nf_register_afinfo
);
43 void nf_unregister_afinfo(struct nf_afinfo
*afinfo
)
45 spin_lock(&afinfo_lock
);
46 rcu_assign_pointer(nf_afinfo
[afinfo
->family
], NULL
);
47 spin_unlock(&afinfo_lock
);
50 EXPORT_SYMBOL_GPL(nf_unregister_afinfo
);
52 /* In this code, we can be waiting indefinitely for userspace to
53 * service a packet if a hook returns NF_QUEUE. We could keep a count
54 * of skbuffs queued for userspace, and not deregister a hook unless
55 * this is zero, but that sucks. Now, we simply check when the
56 * packets come back: if the hook is gone, the packet is discarded. */
57 struct list_head nf_hooks
[NPROTO
][NF_MAX_HOOKS
];
58 EXPORT_SYMBOL(nf_hooks
);
59 static DEFINE_SPINLOCK(nf_hook_lock
);
61 int nf_register_hook(struct nf_hook_ops
*reg
)
65 spin_lock_bh(&nf_hook_lock
);
66 list_for_each(i
, &nf_hooks
[reg
->pf
][reg
->hooknum
]) {
67 if (reg
->priority
< ((struct nf_hook_ops
*)i
)->priority
)
70 list_add_rcu(®
->list
, i
->prev
);
71 spin_unlock_bh(&nf_hook_lock
);
76 EXPORT_SYMBOL(nf_register_hook
);
78 void nf_unregister_hook(struct nf_hook_ops
*reg
)
80 spin_lock_bh(&nf_hook_lock
);
81 list_del_rcu(®
->list
);
82 spin_unlock_bh(&nf_hook_lock
);
86 EXPORT_SYMBOL(nf_unregister_hook
);
88 int nf_register_hooks(struct nf_hook_ops
*reg
, unsigned int n
)
93 for (i
= 0; i
< n
; i
++) {
94 err
= nf_register_hook(®
[i
]);
102 nf_unregister_hooks(reg
, i
);
105 EXPORT_SYMBOL(nf_register_hooks
);
107 void nf_unregister_hooks(struct nf_hook_ops
*reg
, unsigned int n
)
111 for (i
= 0; i
< n
; i
++)
112 nf_unregister_hook(®
[i
]);
114 EXPORT_SYMBOL(nf_unregister_hooks
);
116 unsigned int nf_iterate(struct list_head
*head
,
117 struct sk_buff
**skb
,
119 const struct net_device
*indev
,
120 const struct net_device
*outdev
,
121 struct list_head
**i
,
122 int (*okfn
)(struct sk_buff
*),
125 unsigned int verdict
;
128 * The caller must not block between calls to this
129 * function because of risk of continuing from deleted element.
131 list_for_each_continue_rcu(*i
, head
) {
132 struct nf_hook_ops
*elem
= (struct nf_hook_ops
*)*i
;
134 if (hook_thresh
> elem
->priority
)
137 /* Optimization: we don't need to hold module
138 reference here, since function can't sleep. --RR */
139 verdict
= elem
->hook(hook
, skb
, indev
, outdev
, okfn
);
140 if (verdict
!= NF_ACCEPT
) {
141 #ifdef CONFIG_NETFILTER_DEBUG
142 if (unlikely((verdict
& NF_VERDICT_MASK
)
144 NFDEBUG("Evil return from %p(%u).\n",
149 if (verdict
!= NF_REPEAT
)
158 /* Returns 1 if okfn() needs to be executed by the caller,
159 * -EPERM for NF_DROP, 0 otherwise. */
160 int nf_hook_slow(int pf
, unsigned int hook
, struct sk_buff
**pskb
,
161 struct net_device
*indev
,
162 struct net_device
*outdev
,
163 int (*okfn
)(struct sk_buff
*),
166 struct list_head
*elem
;
167 unsigned int verdict
;
170 /* We may already have this, but read-locks nest anyway */
173 elem
= &nf_hooks
[pf
][hook
];
175 verdict
= nf_iterate(&nf_hooks
[pf
][hook
], pskb
, hook
, indev
,
176 outdev
, &elem
, okfn
, hook_thresh
);
177 if (verdict
== NF_ACCEPT
|| verdict
== NF_STOP
) {
180 } else if (verdict
== NF_DROP
) {
183 } else if ((verdict
& NF_VERDICT_MASK
) == NF_QUEUE
) {
184 NFDEBUG("nf_hook: Verdict = QUEUE.\n");
185 if (!nf_queue(pskb
, elem
, pf
, hook
, indev
, outdev
, okfn
,
186 verdict
>> NF_VERDICT_BITS
))
193 EXPORT_SYMBOL(nf_hook_slow
);
196 int skb_make_writable(struct sk_buff
**pskb
, unsigned int writable_len
)
198 struct sk_buff
*nskb
;
200 if (writable_len
> (*pskb
)->len
)
203 /* Not exclusive use of packet? Must copy. */
204 if (skb_shared(*pskb
) || skb_cloned(*pskb
))
207 return pskb_may_pull(*pskb
, writable_len
);
210 nskb
= skb_copy(*pskb
, GFP_ATOMIC
);
213 BUG_ON(skb_is_nonlinear(nskb
));
215 /* Rest of kernel will get very unhappy if we pass it a
216 suddenly-orphaned skbuff */
218 skb_set_owner_w(nskb
, (*pskb
)->sk
);
223 EXPORT_SYMBOL(skb_make_writable
);
226 /* This does not belong here, but locally generated errors need it if connection
227 tracking in use: without this, connection may not be in hash table, and hence
228 manufactured ICMP or RST packets will not be associated with it. */
229 void (*ip_ct_attach
)(struct sk_buff
*, struct sk_buff
*);
230 EXPORT_SYMBOL(ip_ct_attach
);
232 void nf_ct_attach(struct sk_buff
*new, struct sk_buff
*skb
)
234 void (*attach
)(struct sk_buff
*, struct sk_buff
*);
236 if (skb
->nfct
&& (attach
= ip_ct_attach
) != NULL
) {
237 mb(); /* Just to be sure: must be read before executing this */
241 EXPORT_SYMBOL(nf_ct_attach
);
243 #ifdef CONFIG_PROC_FS
244 struct proc_dir_entry
*proc_net_netfilter
;
245 EXPORT_SYMBOL(proc_net_netfilter
);
248 void __init
netfilter_init(void)
251 for (i
= 0; i
< NPROTO
; i
++) {
252 for (h
= 0; h
< NF_MAX_HOOKS
; h
++)
253 INIT_LIST_HEAD(&nf_hooks
[i
][h
]);
256 #ifdef CONFIG_PROC_FS
257 proc_net_netfilter
= proc_mkdir("netfilter", proc_net
);
258 if (!proc_net_netfilter
)
259 panic("cannot create netfilter proc entry");
262 if (netfilter_queue_init() < 0)
263 panic("cannot initialize nf_queue");
264 if (netfilter_log_init() < 0)
265 panic("cannot initialize nf_log");