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.
8 * Patrick McHardy (c) 2006-2012
10 #include <linux/kernel.h>
11 #include <linux/netfilter.h>
12 #include <net/protocol.h>
13 #include <linux/init.h>
14 #include <linux/skbuff.h>
15 #include <linux/wait.h>
16 #include <linux/module.h>
17 #include <linux/interrupt.h>
19 #include <linux/netdevice.h>
20 #include <linux/inetdevice.h>
21 #include <linux/proc_fs.h>
22 #include <linux/mutex.h>
23 #include <linux/slab.h>
24 #include <net/net_namespace.h>
27 #include "nf_internals.h"
29 static DEFINE_MUTEX(afinfo_mutex
);
31 const struct nf_afinfo __rcu
*nf_afinfo
[NFPROTO_NUMPROTO
] __read_mostly
;
32 EXPORT_SYMBOL(nf_afinfo
);
34 int nf_register_afinfo(const struct nf_afinfo
*afinfo
)
38 err
= mutex_lock_interruptible(&afinfo_mutex
);
41 RCU_INIT_POINTER(nf_afinfo
[afinfo
->family
], afinfo
);
42 mutex_unlock(&afinfo_mutex
);
45 EXPORT_SYMBOL_GPL(nf_register_afinfo
);
47 void nf_unregister_afinfo(const struct nf_afinfo
*afinfo
)
49 mutex_lock(&afinfo_mutex
);
50 RCU_INIT_POINTER(nf_afinfo
[afinfo
->family
], NULL
);
51 mutex_unlock(&afinfo_mutex
);
54 EXPORT_SYMBOL_GPL(nf_unregister_afinfo
);
56 struct list_head nf_hooks
[NFPROTO_NUMPROTO
][NF_MAX_HOOKS
] __read_mostly
;
57 EXPORT_SYMBOL(nf_hooks
);
59 #if defined(CONFIG_JUMP_LABEL)
60 struct static_key nf_hooks_needed
[NFPROTO_NUMPROTO
][NF_MAX_HOOKS
];
61 EXPORT_SYMBOL(nf_hooks_needed
);
64 static DEFINE_MUTEX(nf_hook_mutex
);
66 int nf_register_hook(struct nf_hook_ops
*reg
)
68 struct nf_hook_ops
*elem
;
71 err
= mutex_lock_interruptible(&nf_hook_mutex
);
74 list_for_each_entry(elem
, &nf_hooks
[reg
->pf
][reg
->hooknum
], list
) {
75 if (reg
->priority
< elem
->priority
)
78 list_add_rcu(®
->list
, elem
->list
.prev
);
79 mutex_unlock(&nf_hook_mutex
);
80 #if defined(CONFIG_JUMP_LABEL)
81 static_key_slow_inc(&nf_hooks_needed
[reg
->pf
][reg
->hooknum
]);
85 EXPORT_SYMBOL(nf_register_hook
);
87 void nf_unregister_hook(struct nf_hook_ops
*reg
)
89 mutex_lock(&nf_hook_mutex
);
90 list_del_rcu(®
->list
);
91 mutex_unlock(&nf_hook_mutex
);
92 #if defined(CONFIG_JUMP_LABEL)
93 static_key_slow_dec(&nf_hooks_needed
[reg
->pf
][reg
->hooknum
]);
97 EXPORT_SYMBOL(nf_unregister_hook
);
99 int nf_register_hooks(struct nf_hook_ops
*reg
, unsigned int n
)
104 for (i
= 0; i
< n
; i
++) {
105 err
= nf_register_hook(®
[i
]);
113 nf_unregister_hooks(reg
, i
);
116 EXPORT_SYMBOL(nf_register_hooks
);
118 void nf_unregister_hooks(struct nf_hook_ops
*reg
, unsigned int n
)
121 nf_unregister_hook(®
[n
]);
123 EXPORT_SYMBOL(nf_unregister_hooks
);
125 unsigned int nf_iterate(struct list_head
*head
,
128 const struct net_device
*indev
,
129 const struct net_device
*outdev
,
130 struct nf_hook_ops
**elemp
,
131 int (*okfn
)(struct sk_buff
*),
134 unsigned int verdict
;
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((*elemp
), head
, list
) {
141 if (hook_thresh
> (*elemp
)->priority
)
144 /* Optimization: we don't need to hold module
145 reference here, since function can't sleep. --RR */
147 verdict
= (*elemp
)->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",
153 (*elemp
)->hook
, hook
);
157 if (verdict
!= NF_REPEAT
)
166 /* Returns 1 if okfn() needs to be executed by the caller,
167 * -EPERM for NF_DROP, 0 otherwise. */
168 int nf_hook_slow(u_int8_t pf
, unsigned int hook
, struct sk_buff
*skb
,
169 struct net_device
*indev
,
170 struct net_device
*outdev
,
171 int (*okfn
)(struct sk_buff
*),
174 struct nf_hook_ops
*elem
;
175 unsigned int verdict
;
178 /* We may already have this, but read-locks nest anyway */
181 elem
= list_entry_rcu(&nf_hooks
[pf
][hook
], struct nf_hook_ops
, list
);
183 verdict
= nf_iterate(&nf_hooks
[pf
][hook
], skb
, hook
, indev
,
184 outdev
, &elem
, okfn
, hook_thresh
);
185 if (verdict
== NF_ACCEPT
|| verdict
== NF_STOP
) {
187 } else if ((verdict
& NF_VERDICT_MASK
) == NF_DROP
) {
189 ret
= NF_DROP_GETERR(verdict
);
192 } else if ((verdict
& NF_VERDICT_MASK
) == NF_QUEUE
) {
193 int err
= nf_queue(skb
, elem
, pf
, hook
, indev
, outdev
, okfn
,
194 verdict
>> NF_VERDICT_QBITS
);
196 if (err
== -ECANCELED
)
199 (verdict
& NF_VERDICT_FLAG_QUEUE_BYPASS
))
207 EXPORT_SYMBOL(nf_hook_slow
);
210 int skb_make_writable(struct sk_buff
*skb
, unsigned int writable_len
)
212 if (writable_len
> skb
->len
)
215 /* Not exclusive use of packet? Must copy. */
216 if (!skb_cloned(skb
)) {
217 if (writable_len
<= skb_headlen(skb
))
219 } else if (skb_clone_writable(skb
, writable_len
))
222 if (writable_len
<= skb_headlen(skb
))
225 writable_len
-= skb_headlen(skb
);
227 return !!__pskb_pull_tail(skb
, writable_len
);
229 EXPORT_SYMBOL(skb_make_writable
);
231 #if IS_ENABLED(CONFIG_NF_CONNTRACK)
232 /* This does not belong here, but locally generated errors need it if connection
233 tracking in use: without this, connection may not be in hash table, and hence
234 manufactured ICMP or RST packets will not be associated with it. */
235 void (*ip_ct_attach
)(struct sk_buff
*, struct sk_buff
*) __rcu __read_mostly
;
236 EXPORT_SYMBOL(ip_ct_attach
);
238 void nf_ct_attach(struct sk_buff
*new, struct sk_buff
*skb
)
240 void (*attach
)(struct sk_buff
*, struct sk_buff
*);
244 attach
= rcu_dereference(ip_ct_attach
);
250 EXPORT_SYMBOL(nf_ct_attach
);
252 void (*nf_ct_destroy
)(struct nf_conntrack
*) __rcu __read_mostly
;
253 EXPORT_SYMBOL(nf_ct_destroy
);
255 void nf_conntrack_destroy(struct nf_conntrack
*nfct
)
257 void (*destroy
)(struct nf_conntrack
*);
260 destroy
= rcu_dereference(nf_ct_destroy
);
261 BUG_ON(destroy
== NULL
);
265 EXPORT_SYMBOL(nf_conntrack_destroy
);
267 struct nfq_ct_hook __rcu
*nfq_ct_hook __read_mostly
;
268 EXPORT_SYMBOL_GPL(nfq_ct_hook
);
270 struct nfq_ct_nat_hook __rcu
*nfq_ct_nat_hook __read_mostly
;
271 EXPORT_SYMBOL_GPL(nfq_ct_nat_hook
);
273 #endif /* CONFIG_NF_CONNTRACK */
275 #ifdef CONFIG_NF_NAT_NEEDED
276 void (*nf_nat_decode_session_hook
)(struct sk_buff
*, struct flowi
*);
277 EXPORT_SYMBOL(nf_nat_decode_session_hook
);
280 static int __net_init
netfilter_net_init(struct net
*net
)
282 #ifdef CONFIG_PROC_FS
283 net
->nf
.proc_netfilter
= proc_net_mkdir(net
, "netfilter",
285 if (!net
->nf
.proc_netfilter
) {
286 if (!net_eq(net
, &init_net
))
287 pr_err("cannot create netfilter proc entry");
295 static void __net_exit
netfilter_net_exit(struct net
*net
)
297 remove_proc_entry("netfilter", net
->proc_net
);
300 static struct pernet_operations netfilter_net_ops
= {
301 .init
= netfilter_net_init
,
302 .exit
= netfilter_net_exit
,
305 void __init
netfilter_init(void)
308 for (i
= 0; i
< ARRAY_SIZE(nf_hooks
); i
++) {
309 for (h
= 0; h
< NF_MAX_HOOKS
; h
++)
310 INIT_LIST_HEAD(&nf_hooks
[i
][h
]);
313 if (register_pernet_subsys(&netfilter_net_ops
) < 0)
314 panic("cannot create netfilter proc entry");
316 if (netfilter_log_init() < 0)
317 panic("cannot initialize nf_log");