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601e68e1 | 1 | /* netfilter.c: look after the filters for various protocols. |
f6ebe77f HW |
2 | * Heavily influenced by the old firewall.c by David Bonn and Alan Cox. |
3 | * | |
4 | * Thanks to Rob `CmdrTaco' Malda for not influencing this code in any | |
5 | * way. | |
6 | * | |
7 | * Rusty Russell (C)2000 -- This code is GPL. | |
f6ebe77f | 8 | */ |
f6ebe77f HW |
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> | |
17 | #include <linux/if.h> | |
18 | #include <linux/netdevice.h> | |
19 | #include <linux/inetdevice.h> | |
20 | #include <linux/proc_fs.h> | |
d486dd1f | 21 | #include <linux/mutex.h> |
f6ebe77f HW |
22 | #include <net/sock.h> |
23 | ||
24 | #include "nf_internals.h" | |
25 | ||
d486dd1f | 26 | static DEFINE_MUTEX(afinfo_mutex); |
bce8032e | 27 | |
e2b7606c | 28 | struct nf_afinfo *nf_afinfo[NPROTO] __read_mostly; |
bce8032e PM |
29 | EXPORT_SYMBOL(nf_afinfo); |
30 | ||
31 | int nf_register_afinfo(struct nf_afinfo *afinfo) | |
32 | { | |
d486dd1f PM |
33 | int err; |
34 | ||
35 | err = mutex_lock_interruptible(&afinfo_mutex); | |
36 | if (err < 0) | |
37 | return err; | |
bce8032e | 38 | rcu_assign_pointer(nf_afinfo[afinfo->family], afinfo); |
d486dd1f | 39 | mutex_unlock(&afinfo_mutex); |
bce8032e PM |
40 | return 0; |
41 | } | |
42 | EXPORT_SYMBOL_GPL(nf_register_afinfo); | |
43 | ||
44 | void nf_unregister_afinfo(struct nf_afinfo *afinfo) | |
45 | { | |
d486dd1f | 46 | mutex_lock(&afinfo_mutex); |
bce8032e | 47 | rcu_assign_pointer(nf_afinfo[afinfo->family], NULL); |
d486dd1f | 48 | mutex_unlock(&afinfo_mutex); |
bce8032e PM |
49 | synchronize_rcu(); |
50 | } | |
51 | EXPORT_SYMBOL_GPL(nf_unregister_afinfo); | |
52 | ||
f6ebe77f HW |
53 | /* In this code, we can be waiting indefinitely for userspace to |
54 | * service a packet if a hook returns NF_QUEUE. We could keep a count | |
55 | * of skbuffs queued for userspace, and not deregister a hook unless | |
56 | * this is zero, but that sucks. Now, we simply check when the | |
57 | * packets come back: if the hook is gone, the packet is discarded. */ | |
e2b7606c | 58 | struct list_head nf_hooks[NPROTO][NF_MAX_HOOKS] __read_mostly; |
f6ebe77f | 59 | EXPORT_SYMBOL(nf_hooks); |
fd706d69 | 60 | static DEFINE_MUTEX(nf_hook_mutex); |
f6ebe77f HW |
61 | |
62 | int nf_register_hook(struct nf_hook_ops *reg) | |
63 | { | |
64 | struct list_head *i; | |
fd706d69 | 65 | int err; |
f6ebe77f | 66 | |
fd706d69 PM |
67 | err = mutex_lock_interruptible(&nf_hook_mutex); |
68 | if (err < 0) | |
69 | return err; | |
f6ebe77f HW |
70 | list_for_each(i, &nf_hooks[reg->pf][reg->hooknum]) { |
71 | if (reg->priority < ((struct nf_hook_ops *)i)->priority) | |
72 | break; | |
73 | } | |
74 | list_add_rcu(®->list, i->prev); | |
fd706d69 | 75 | mutex_unlock(&nf_hook_mutex); |
f6ebe77f HW |
76 | return 0; |
77 | } | |
78 | EXPORT_SYMBOL(nf_register_hook); | |
79 | ||
80 | void nf_unregister_hook(struct nf_hook_ops *reg) | |
81 | { | |
fd706d69 | 82 | mutex_lock(&nf_hook_mutex); |
f6ebe77f | 83 | list_del_rcu(®->list); |
fd706d69 | 84 | mutex_unlock(&nf_hook_mutex); |
f6ebe77f HW |
85 | |
86 | synchronize_net(); | |
87 | } | |
88 | EXPORT_SYMBOL(nf_unregister_hook); | |
89 | ||
972d1cb1 PM |
90 | int nf_register_hooks(struct nf_hook_ops *reg, unsigned int n) |
91 | { | |
92 | unsigned int i; | |
93 | int err = 0; | |
94 | ||
95 | for (i = 0; i < n; i++) { | |
96 | err = nf_register_hook(®[i]); | |
97 | if (err) | |
98 | goto err; | |
99 | } | |
100 | return err; | |
101 | ||
102 | err: | |
103 | if (i > 0) | |
104 | nf_unregister_hooks(reg, i); | |
105 | return err; | |
106 | } | |
107 | EXPORT_SYMBOL(nf_register_hooks); | |
108 | ||
109 | void nf_unregister_hooks(struct nf_hook_ops *reg, unsigned int n) | |
110 | { | |
111 | unsigned int i; | |
112 | ||
113 | for (i = 0; i < n; i++) | |
114 | nf_unregister_hook(®[i]); | |
115 | } | |
116 | EXPORT_SYMBOL(nf_unregister_hooks); | |
117 | ||
f6ebe77f HW |
118 | unsigned int nf_iterate(struct list_head *head, |
119 | struct sk_buff **skb, | |
120 | int hook, | |
121 | const struct net_device *indev, | |
122 | const struct net_device *outdev, | |
123 | struct list_head **i, | |
124 | int (*okfn)(struct sk_buff *), | |
125 | int hook_thresh) | |
126 | { | |
127 | unsigned int verdict; | |
128 | ||
129 | /* | |
130 | * The caller must not block between calls to this | |
131 | * function because of risk of continuing from deleted element. | |
132 | */ | |
133 | list_for_each_continue_rcu(*i, head) { | |
134 | struct nf_hook_ops *elem = (struct nf_hook_ops *)*i; | |
135 | ||
136 | if (hook_thresh > elem->priority) | |
137 | continue; | |
138 | ||
139 | /* Optimization: we don't need to hold module | |
601e68e1 | 140 | reference here, since function can't sleep. --RR */ |
f6ebe77f HW |
141 | verdict = elem->hook(hook, skb, indev, outdev, okfn); |
142 | if (verdict != NF_ACCEPT) { | |
143 | #ifdef CONFIG_NETFILTER_DEBUG | |
144 | if (unlikely((verdict & NF_VERDICT_MASK) | |
145 | > NF_MAX_VERDICT)) { | |
146 | NFDEBUG("Evil return from %p(%u).\n", | |
601e68e1 | 147 | elem->hook, hook); |
f6ebe77f HW |
148 | continue; |
149 | } | |
150 | #endif | |
151 | if (verdict != NF_REPEAT) | |
152 | return verdict; | |
153 | *i = (*i)->prev; | |
154 | } | |
155 | } | |
156 | return NF_ACCEPT; | |
157 | } | |
158 | ||
159 | ||
160 | /* Returns 1 if okfn() needs to be executed by the caller, | |
161 | * -EPERM for NF_DROP, 0 otherwise. */ | |
162 | int nf_hook_slow(int pf, unsigned int hook, struct sk_buff **pskb, | |
163 | struct net_device *indev, | |
164 | struct net_device *outdev, | |
165 | int (*okfn)(struct sk_buff *), | |
166 | int hook_thresh) | |
167 | { | |
168 | struct list_head *elem; | |
169 | unsigned int verdict; | |
170 | int ret = 0; | |
171 | ||
172 | /* We may already have this, but read-locks nest anyway */ | |
173 | rcu_read_lock(); | |
174 | ||
175 | elem = &nf_hooks[pf][hook]; | |
176 | next_hook: | |
177 | verdict = nf_iterate(&nf_hooks[pf][hook], pskb, hook, indev, | |
178 | outdev, &elem, okfn, hook_thresh); | |
179 | if (verdict == NF_ACCEPT || verdict == NF_STOP) { | |
180 | ret = 1; | |
181 | goto unlock; | |
182 | } else if (verdict == NF_DROP) { | |
183 | kfree_skb(*pskb); | |
184 | ret = -EPERM; | |
185 | } else if ((verdict & NF_VERDICT_MASK) == NF_QUEUE) { | |
186 | NFDEBUG("nf_hook: Verdict = QUEUE.\n"); | |
394f545d | 187 | if (!nf_queue(*pskb, elem, pf, hook, indev, outdev, okfn, |
f6ebe77f HW |
188 | verdict >> NF_VERDICT_BITS)) |
189 | goto next_hook; | |
190 | } | |
191 | unlock: | |
192 | rcu_read_unlock(); | |
193 | return ret; | |
194 | } | |
195 | EXPORT_SYMBOL(nf_hook_slow); | |
196 | ||
197 | ||
198 | int skb_make_writable(struct sk_buff **pskb, unsigned int writable_len) | |
199 | { | |
200 | struct sk_buff *nskb; | |
201 | ||
202 | if (writable_len > (*pskb)->len) | |
203 | return 0; | |
204 | ||
205 | /* Not exclusive use of packet? Must copy. */ | |
334a8132 PM |
206 | if (skb_cloned(*pskb) && !skb_clone_writable(*pskb, writable_len)) |
207 | goto copy_skb; | |
208 | if (skb_shared(*pskb)) | |
f6ebe77f HW |
209 | goto copy_skb; |
210 | ||
211 | return pskb_may_pull(*pskb, writable_len); | |
212 | ||
213 | copy_skb: | |
214 | nskb = skb_copy(*pskb, GFP_ATOMIC); | |
215 | if (!nskb) | |
216 | return 0; | |
217 | BUG_ON(skb_is_nonlinear(nskb)); | |
218 | ||
219 | /* Rest of kernel will get very unhappy if we pass it a | |
220 | suddenly-orphaned skbuff */ | |
221 | if ((*pskb)->sk) | |
222 | skb_set_owner_w(nskb, (*pskb)->sk); | |
223 | kfree_skb(*pskb); | |
224 | *pskb = nskb; | |
225 | return 1; | |
226 | } | |
227 | EXPORT_SYMBOL(skb_make_writable); | |
228 | ||
43bc0ca7 AV |
229 | void nf_proto_csum_replace4(__sum16 *sum, struct sk_buff *skb, |
230 | __be32 from, __be32 to, int pseudohdr) | |
4cf411de | 231 | { |
43bc0ca7 | 232 | __be32 diff[] = { ~from, to }; |
4cf411de | 233 | if (skb->ip_summed != CHECKSUM_PARTIAL) { |
a47362a2 | 234 | *sum = csum_fold(csum_partial(diff, sizeof(diff), |
43bc0ca7 | 235 | ~csum_unfold(*sum))); |
4cf411de | 236 | if (skb->ip_summed == CHECKSUM_COMPLETE && pseudohdr) |
a47362a2 | 237 | skb->csum = ~csum_partial(diff, sizeof(diff), |
43bc0ca7 | 238 | ~skb->csum); |
4cf411de | 239 | } else if (pseudohdr) |
a47362a2 | 240 | *sum = ~csum_fold(csum_partial(diff, sizeof(diff), |
43bc0ca7 | 241 | csum_unfold(*sum))); |
4cf411de | 242 | } |
43bc0ca7 | 243 | EXPORT_SYMBOL(nf_proto_csum_replace4); |
f6ebe77f | 244 | |
5f79e0f9 | 245 | #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE) |
f6ebe77f HW |
246 | /* This does not belong here, but locally generated errors need it if connection |
247 | tracking in use: without this, connection may not be in hash table, and hence | |
248 | manufactured ICMP or RST packets will not be associated with it. */ | |
249 | void (*ip_ct_attach)(struct sk_buff *, struct sk_buff *); | |
250 | EXPORT_SYMBOL(ip_ct_attach); | |
251 | ||
252 | void nf_ct_attach(struct sk_buff *new, struct sk_buff *skb) | |
253 | { | |
254 | void (*attach)(struct sk_buff *, struct sk_buff *); | |
255 | ||
c3a47ab3 PM |
256 | if (skb->nfct) { |
257 | rcu_read_lock(); | |
258 | attach = rcu_dereference(ip_ct_attach); | |
259 | if (attach) | |
260 | attach(new, skb); | |
261 | rcu_read_unlock(); | |
f6ebe77f HW |
262 | } |
263 | } | |
264 | EXPORT_SYMBOL(nf_ct_attach); | |
de6e05c4 YK |
265 | |
266 | void (*nf_ct_destroy)(struct nf_conntrack *); | |
267 | EXPORT_SYMBOL(nf_ct_destroy); | |
268 | ||
269 | void nf_conntrack_destroy(struct nf_conntrack *nfct) | |
270 | { | |
271 | void (*destroy)(struct nf_conntrack *); | |
272 | ||
273 | rcu_read_lock(); | |
274 | destroy = rcu_dereference(nf_ct_destroy); | |
275 | BUG_ON(destroy == NULL); | |
276 | destroy(nfct); | |
277 | rcu_read_unlock(); | |
278 | } | |
279 | EXPORT_SYMBOL(nf_conntrack_destroy); | |
280 | #endif /* CONFIG_NF_CONNTRACK */ | |
f6ebe77f HW |
281 | |
282 | #ifdef CONFIG_PROC_FS | |
283 | struct proc_dir_entry *proc_net_netfilter; | |
284 | EXPORT_SYMBOL(proc_net_netfilter); | |
285 | #endif | |
286 | ||
287 | void __init netfilter_init(void) | |
288 | { | |
289 | int i, h; | |
290 | for (i = 0; i < NPROTO; i++) { | |
291 | for (h = 0; h < NF_MAX_HOOKS; h++) | |
292 | INIT_LIST_HEAD(&nf_hooks[i][h]); | |
293 | } | |
294 | ||
295 | #ifdef CONFIG_PROC_FS | |
296 | proc_net_netfilter = proc_mkdir("netfilter", proc_net); | |
297 | if (!proc_net_netfilter) | |
298 | panic("cannot create netfilter proc entry"); | |
299 | #endif | |
300 | ||
301 | if (netfilter_queue_init() < 0) | |
302 | panic("cannot initialize nf_queue"); | |
303 | if (netfilter_log_init() < 0) | |
304 | panic("cannot initialize nf_log"); | |
305 | } |