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 <linux/slab.h>
23 #include <net/net_namespace.h>
26 #include "nf_internals.h"
28 static DEFINE_MUTEX(afinfo_mutex
);
30 const struct nf_afinfo __rcu
*nf_afinfo
[NFPROTO_NUMPROTO
] __read_mostly
;
31 EXPORT_SYMBOL(nf_afinfo
);
33 int nf_register_afinfo(const struct nf_afinfo
*afinfo
)
37 err
= mutex_lock_interruptible(&afinfo_mutex
);
40 RCU_INIT_POINTER(nf_afinfo
[afinfo
->family
], afinfo
);
41 mutex_unlock(&afinfo_mutex
);
44 EXPORT_SYMBOL_GPL(nf_register_afinfo
);
46 void nf_unregister_afinfo(const struct nf_afinfo
*afinfo
)
48 mutex_lock(&afinfo_mutex
);
49 RCU_INIT_POINTER(nf_afinfo
[afinfo
->family
], NULL
);
50 mutex_unlock(&afinfo_mutex
);
53 EXPORT_SYMBOL_GPL(nf_unregister_afinfo
);
55 struct list_head nf_hooks
[NFPROTO_NUMPROTO
][NF_MAX_HOOKS
] __read_mostly
;
56 EXPORT_SYMBOL(nf_hooks
);
58 #if defined(CONFIG_JUMP_LABEL)
59 struct static_key nf_hooks_needed
[NFPROTO_NUMPROTO
][NF_MAX_HOOKS
];
60 EXPORT_SYMBOL(nf_hooks_needed
);
63 static DEFINE_MUTEX(nf_hook_mutex
);
65 int nf_register_hook(struct nf_hook_ops
*reg
)
67 struct nf_hook_ops
*elem
;
70 err
= mutex_lock_interruptible(&nf_hook_mutex
);
73 list_for_each_entry(elem
, &nf_hooks
[reg
->pf
][reg
->hooknum
], list
) {
74 if (reg
->priority
< elem
->priority
)
77 list_add_rcu(®
->list
, elem
->list
.prev
);
78 mutex_unlock(&nf_hook_mutex
);
79 #if defined(CONFIG_JUMP_LABEL)
80 static_key_slow_inc(&nf_hooks_needed
[reg
->pf
][reg
->hooknum
]);
84 EXPORT_SYMBOL(nf_register_hook
);
86 void nf_unregister_hook(struct nf_hook_ops
*reg
)
88 mutex_lock(&nf_hook_mutex
);
89 list_del_rcu(®
->list
);
90 mutex_unlock(&nf_hook_mutex
);
91 #if defined(CONFIG_JUMP_LABEL)
92 static_key_slow_dec(&nf_hooks_needed
[reg
->pf
][reg
->hooknum
]);
96 EXPORT_SYMBOL(nf_unregister_hook
);
98 int nf_register_hooks(struct nf_hook_ops
*reg
, unsigned int n
)
103 for (i
= 0; i
< n
; i
++) {
104 err
= nf_register_hook(®
[i
]);
112 nf_unregister_hooks(reg
, i
);
115 EXPORT_SYMBOL(nf_register_hooks
);
117 void nf_unregister_hooks(struct nf_hook_ops
*reg
, unsigned int n
)
120 nf_unregister_hook(®
[n
]);
122 EXPORT_SYMBOL(nf_unregister_hooks
);
124 unsigned int nf_iterate(struct list_head
*head
,
127 const struct net_device
*indev
,
128 const struct net_device
*outdev
,
129 struct list_head
**i
,
130 int (*okfn
)(struct sk_buff
*),
133 unsigned int verdict
;
134 struct nf_hook_ops
*elem
= list_entry_rcu(*i
, struct nf_hook_ops
, list
);
137 * The caller must not block between calls to this
138 * function because of risk of continuing from deleted element.
140 list_for_each_entry_continue_rcu(elem
, head
, list
) {
141 if (hook_thresh
> elem
->priority
)
144 /* Optimization: we don't need to hold module
145 reference here, since function can't sleep. --RR */
147 verdict
= elem
->hook(hook
, skb
, indev
, outdev
, okfn
);
148 if (verdict
!= NF_ACCEPT
) {
149 #ifdef CONFIG_NETFILTER_DEBUG
150 if (unlikely((verdict
& NF_VERDICT_MASK
)
152 NFDEBUG("Evil return from %p(%u).\n",
157 if (verdict
!= NF_REPEAT
) {
169 /* Returns 1 if okfn() needs to be executed by the caller,
170 * -EPERM for NF_DROP, 0 otherwise. */
171 int nf_hook_slow(u_int8_t pf
, unsigned int hook
, struct sk_buff
*skb
,
172 struct net_device
*indev
,
173 struct net_device
*outdev
,
174 int (*okfn
)(struct sk_buff
*),
177 struct list_head
*elem
;
178 unsigned int verdict
;
181 /* We may already have this, but read-locks nest anyway */
184 elem
= &nf_hooks
[pf
][hook
];
186 verdict
= nf_iterate(&nf_hooks
[pf
][hook
], skb
, hook
, indev
,
187 outdev
, &elem
, okfn
, hook_thresh
);
188 if (verdict
== NF_ACCEPT
|| verdict
== NF_STOP
) {
190 } else if ((verdict
& NF_VERDICT_MASK
) == NF_DROP
) {
192 ret
= NF_DROP_GETERR(verdict
);
195 } else if ((verdict
& NF_VERDICT_MASK
) == NF_QUEUE
) {
196 int err
= nf_queue(skb
, elem
, pf
, hook
, indev
, outdev
, okfn
,
197 verdict
>> NF_VERDICT_QBITS
);
199 if (err
== -ECANCELED
)
202 (verdict
& NF_VERDICT_FLAG_QUEUE_BYPASS
))
210 EXPORT_SYMBOL(nf_hook_slow
);
213 int skb_make_writable(struct sk_buff
*skb
, unsigned int writable_len
)
215 if (writable_len
> skb
->len
)
218 /* Not exclusive use of packet? Must copy. */
219 if (!skb_cloned(skb
)) {
220 if (writable_len
<= skb_headlen(skb
))
222 } else if (skb_clone_writable(skb
, writable_len
))
225 if (writable_len
<= skb_headlen(skb
))
228 writable_len
-= skb_headlen(skb
);
230 return !!__pskb_pull_tail(skb
, writable_len
);
232 EXPORT_SYMBOL(skb_make_writable
);
234 #if IS_ENABLED(CONFIG_NF_CONNTRACK)
235 /* This does not belong here, but locally generated errors need it if connection
236 tracking in use: without this, connection may not be in hash table, and hence
237 manufactured ICMP or RST packets will not be associated with it. */
238 void (*ip_ct_attach
)(struct sk_buff
*, struct sk_buff
*) __rcu __read_mostly
;
239 EXPORT_SYMBOL(ip_ct_attach
);
241 void nf_ct_attach(struct sk_buff
*new, struct sk_buff
*skb
)
243 void (*attach
)(struct sk_buff
*, struct sk_buff
*);
247 attach
= rcu_dereference(ip_ct_attach
);
253 EXPORT_SYMBOL(nf_ct_attach
);
255 void (*nf_ct_destroy
)(struct nf_conntrack
*) __rcu __read_mostly
;
256 EXPORT_SYMBOL(nf_ct_destroy
);
258 void nf_conntrack_destroy(struct nf_conntrack
*nfct
)
260 void (*destroy
)(struct nf_conntrack
*);
263 destroy
= rcu_dereference(nf_ct_destroy
);
264 BUG_ON(destroy
== NULL
);
268 EXPORT_SYMBOL(nf_conntrack_destroy
);
270 struct nfq_ct_hook __rcu
*nfq_ct_hook __read_mostly
;
271 EXPORT_SYMBOL_GPL(nfq_ct_hook
);
273 struct nfq_ct_nat_hook __rcu
*nfq_ct_nat_hook __read_mostly
;
274 EXPORT_SYMBOL_GPL(nfq_ct_nat_hook
);
276 #endif /* CONFIG_NF_CONNTRACK */
278 #ifdef CONFIG_NF_NAT_NEEDED
279 void (*nf_nat_decode_session_hook
)(struct sk_buff
*, struct flowi
*);
280 EXPORT_SYMBOL(nf_nat_decode_session_hook
);
283 #ifdef CONFIG_PROC_FS
284 struct proc_dir_entry
*proc_net_netfilter
;
285 EXPORT_SYMBOL(proc_net_netfilter
);
288 void __init
netfilter_init(void)
291 for (i
= 0; i
< ARRAY_SIZE(nf_hooks
); i
++) {
292 for (h
= 0; h
< NF_MAX_HOOKS
; h
++)
293 INIT_LIST_HEAD(&nf_hooks
[i
][h
]);
296 #ifdef CONFIG_PROC_FS
297 proc_net_netfilter
= proc_mkdir("netfilter", init_net
.proc_net
);
298 if (!proc_net_netfilter
)
299 panic("cannot create netfilter proc entry");
302 if (netfilter_queue_init() < 0)
303 panic("cannot initialize nf_queue");
304 if (netfilter_log_init() < 0)
305 panic("cannot initialize nf_log");