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/netfilter_ipv6.h>
21 #include <linux/inetdevice.h>
22 #include <linux/proc_fs.h>
23 #include <linux/mutex.h>
24 #include <linux/slab.h>
25 #include <net/net_namespace.h>
28 #include "nf_internals.h"
30 static DEFINE_MUTEX(afinfo_mutex
);
32 const struct nf_afinfo __rcu
*nf_afinfo
[NFPROTO_NUMPROTO
] __read_mostly
;
33 EXPORT_SYMBOL(nf_afinfo
);
34 const struct nf_ipv6_ops __rcu
*nf_ipv6_ops __read_mostly
;
35 EXPORT_SYMBOL_GPL(nf_ipv6_ops
);
37 int nf_register_afinfo(const struct nf_afinfo
*afinfo
)
39 mutex_lock(&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 #ifdef HAVE_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
;
69 mutex_lock(&nf_hook_mutex
);
70 list_for_each_entry(elem
, &nf_hooks
[reg
->pf
][reg
->hooknum
], list
) {
71 if (reg
->priority
< elem
->priority
)
74 list_add_rcu(®
->list
, elem
->list
.prev
);
75 mutex_unlock(&nf_hook_mutex
);
76 #ifdef HAVE_JUMP_LABEL
77 static_key_slow_inc(&nf_hooks_needed
[reg
->pf
][reg
->hooknum
]);
81 EXPORT_SYMBOL(nf_register_hook
);
83 void nf_unregister_hook(struct nf_hook_ops
*reg
)
85 mutex_lock(&nf_hook_mutex
);
86 list_del_rcu(®
->list
);
87 mutex_unlock(&nf_hook_mutex
);
88 #ifdef HAVE_JUMP_LABEL
89 static_key_slow_dec(&nf_hooks_needed
[reg
->pf
][reg
->hooknum
]);
93 EXPORT_SYMBOL(nf_unregister_hook
);
95 int nf_register_hooks(struct nf_hook_ops
*reg
, unsigned int n
)
100 for (i
= 0; i
< n
; i
++) {
101 err
= nf_register_hook(®
[i
]);
109 nf_unregister_hooks(reg
, i
);
112 EXPORT_SYMBOL(nf_register_hooks
);
114 void nf_unregister_hooks(struct nf_hook_ops
*reg
, unsigned int n
)
117 nf_unregister_hook(®
[n
]);
119 EXPORT_SYMBOL(nf_unregister_hooks
);
121 unsigned int nf_iterate(struct list_head
*head
,
123 struct nf_hook_state
*state
,
124 struct nf_hook_ops
**elemp
)
126 unsigned int verdict
;
129 * The caller must not block between calls to this
130 * function because of risk of continuing from deleted element.
132 list_for_each_entry_continue_rcu((*elemp
), head
, list
) {
133 if (state
->thresh
> (*elemp
)->priority
)
136 /* Optimization: we don't need to hold module
137 reference here, since function can't sleep. --RR */
139 verdict
= (*elemp
)->hook(*elemp
, skb
, state
);
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",
145 (*elemp
)->hook
, state
->hook
);
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(struct sk_buff
*skb
, struct nf_hook_state
*state
)
162 struct nf_hook_ops
*elem
;
163 unsigned int verdict
;
166 /* We may already have this, but read-locks nest anyway */
169 elem
= list_entry_rcu(state
->hook_list
, struct nf_hook_ops
, list
);
171 verdict
= nf_iterate(state
->hook_list
, skb
, state
, &elem
);
172 if (verdict
== NF_ACCEPT
|| verdict
== NF_STOP
) {
174 } else if ((verdict
& NF_VERDICT_MASK
) == NF_DROP
) {
176 ret
= NF_DROP_GETERR(verdict
);
179 } else if ((verdict
& NF_VERDICT_MASK
) == NF_QUEUE
) {
180 int err
= nf_queue(skb
, elem
, state
,
181 verdict
>> NF_VERDICT_QBITS
);
183 if (err
== -ECANCELED
)
186 (verdict
& NF_VERDICT_FLAG_QUEUE_BYPASS
))
194 EXPORT_SYMBOL(nf_hook_slow
);
197 int skb_make_writable(struct sk_buff
*skb
, unsigned int writable_len
)
199 if (writable_len
> skb
->len
)
202 /* Not exclusive use of packet? Must copy. */
203 if (!skb_cloned(skb
)) {
204 if (writable_len
<= skb_headlen(skb
))
206 } else if (skb_clone_writable(skb
, writable_len
))
209 if (writable_len
<= skb_headlen(skb
))
212 writable_len
-= skb_headlen(skb
);
214 return !!__pskb_pull_tail(skb
, writable_len
);
216 EXPORT_SYMBOL(skb_make_writable
);
218 #if IS_ENABLED(CONFIG_NF_CONNTRACK)
219 /* This does not belong here, but locally generated errors need it if connection
220 tracking in use: without this, connection may not be in hash table, and hence
221 manufactured ICMP or RST packets will not be associated with it. */
222 void (*ip_ct_attach
)(struct sk_buff
*, const struct sk_buff
*)
224 EXPORT_SYMBOL(ip_ct_attach
);
226 void nf_ct_attach(struct sk_buff
*new, const struct sk_buff
*skb
)
228 void (*attach
)(struct sk_buff
*, const struct sk_buff
*);
232 attach
= rcu_dereference(ip_ct_attach
);
238 EXPORT_SYMBOL(nf_ct_attach
);
240 void (*nf_ct_destroy
)(struct nf_conntrack
*) __rcu __read_mostly
;
241 EXPORT_SYMBOL(nf_ct_destroy
);
243 void nf_conntrack_destroy(struct nf_conntrack
*nfct
)
245 void (*destroy
)(struct nf_conntrack
*);
248 destroy
= rcu_dereference(nf_ct_destroy
);
249 BUG_ON(destroy
== NULL
);
253 EXPORT_SYMBOL(nf_conntrack_destroy
);
255 struct nfq_ct_hook __rcu
*nfq_ct_hook __read_mostly
;
256 EXPORT_SYMBOL_GPL(nfq_ct_hook
);
258 struct nfq_ct_nat_hook __rcu
*nfq_ct_nat_hook __read_mostly
;
259 EXPORT_SYMBOL_GPL(nfq_ct_nat_hook
);
261 #endif /* CONFIG_NF_CONNTRACK */
263 #ifdef CONFIG_NF_NAT_NEEDED
264 void (*nf_nat_decode_session_hook
)(struct sk_buff
*, struct flowi
*);
265 EXPORT_SYMBOL(nf_nat_decode_session_hook
);
268 static int __net_init
netfilter_net_init(struct net
*net
)
270 #ifdef CONFIG_PROC_FS
271 net
->nf
.proc_netfilter
= proc_net_mkdir(net
, "netfilter",
273 if (!net
->nf
.proc_netfilter
) {
274 if (!net_eq(net
, &init_net
))
275 pr_err("cannot create netfilter proc entry");
283 static void __net_exit
netfilter_net_exit(struct net
*net
)
285 remove_proc_entry("netfilter", net
->proc_net
);
288 static struct pernet_operations netfilter_net_ops
= {
289 .init
= netfilter_net_init
,
290 .exit
= netfilter_net_exit
,
293 int __init
netfilter_init(void)
297 for (i
= 0; i
< ARRAY_SIZE(nf_hooks
); i
++) {
298 for (h
= 0; h
< NF_MAX_HOOKS
; h
++)
299 INIT_LIST_HEAD(&nf_hooks
[i
][h
]);
302 ret
= register_pernet_subsys(&netfilter_net_ops
);
306 ret
= netfilter_log_init();
312 unregister_pernet_subsys(&netfilter_net_ops
);