Commit | Line | Data |
---|---|---|
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. | |
8 | * | |
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. | |
12 | */ | |
f6ebe77f HW |
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> | |
21 | #include <linux/if.h> | |
22 | #include <linux/netdevice.h> | |
23 | #include <linux/inetdevice.h> | |
24 | #include <linux/proc_fs.h> | |
d486dd1f | 25 | #include <linux/mutex.h> |
f6ebe77f HW |
26 | #include <net/sock.h> |
27 | ||
28 | #include "nf_internals.h" | |
29 | ||
d486dd1f | 30 | static DEFINE_MUTEX(afinfo_mutex); |
bce8032e | 31 | |
e2b7606c | 32 | struct nf_afinfo *nf_afinfo[NPROTO] __read_mostly; |
bce8032e PM |
33 | EXPORT_SYMBOL(nf_afinfo); |
34 | ||
35 | int nf_register_afinfo(struct nf_afinfo *afinfo) | |
36 | { | |
d486dd1f PM |
37 | int err; |
38 | ||
39 | err = mutex_lock_interruptible(&afinfo_mutex); | |
40 | if (err < 0) | |
41 | return err; | |
bce8032e | 42 | rcu_assign_pointer(nf_afinfo[afinfo->family], afinfo); |
d486dd1f | 43 | mutex_unlock(&afinfo_mutex); |
bce8032e PM |
44 | return 0; |
45 | } | |
46 | EXPORT_SYMBOL_GPL(nf_register_afinfo); | |
47 | ||
48 | void nf_unregister_afinfo(struct nf_afinfo *afinfo) | |
49 | { | |
d486dd1f | 50 | mutex_lock(&afinfo_mutex); |
bce8032e | 51 | rcu_assign_pointer(nf_afinfo[afinfo->family], NULL); |
d486dd1f | 52 | mutex_unlock(&afinfo_mutex); |
bce8032e PM |
53 | synchronize_rcu(); |
54 | } | |
55 | EXPORT_SYMBOL_GPL(nf_unregister_afinfo); | |
56 | ||
f6ebe77f HW |
57 | /* In this code, we can be waiting indefinitely for userspace to |
58 | * service a packet if a hook returns NF_QUEUE. We could keep a count | |
59 | * of skbuffs queued for userspace, and not deregister a hook unless | |
60 | * this is zero, but that sucks. Now, we simply check when the | |
61 | * packets come back: if the hook is gone, the packet is discarded. */ | |
e2b7606c | 62 | struct list_head nf_hooks[NPROTO][NF_MAX_HOOKS] __read_mostly; |
f6ebe77f | 63 | EXPORT_SYMBOL(nf_hooks); |
fd706d69 | 64 | static DEFINE_MUTEX(nf_hook_mutex); |
f6ebe77f HW |
65 | |
66 | int nf_register_hook(struct nf_hook_ops *reg) | |
67 | { | |
68 | struct list_head *i; | |
fd706d69 | 69 | int err; |
f6ebe77f | 70 | |
fd706d69 PM |
71 | err = mutex_lock_interruptible(&nf_hook_mutex); |
72 | if (err < 0) | |
73 | return err; | |
f6ebe77f HW |
74 | list_for_each(i, &nf_hooks[reg->pf][reg->hooknum]) { |
75 | if (reg->priority < ((struct nf_hook_ops *)i)->priority) | |
76 | break; | |
77 | } | |
78 | list_add_rcu(®->list, i->prev); | |
fd706d69 | 79 | mutex_unlock(&nf_hook_mutex); |
f6ebe77f HW |
80 | return 0; |
81 | } | |
82 | EXPORT_SYMBOL(nf_register_hook); | |
83 | ||
84 | void nf_unregister_hook(struct nf_hook_ops *reg) | |
85 | { | |
fd706d69 | 86 | mutex_lock(&nf_hook_mutex); |
f6ebe77f | 87 | list_del_rcu(®->list); |
fd706d69 | 88 | mutex_unlock(&nf_hook_mutex); |
f6ebe77f HW |
89 | |
90 | synchronize_net(); | |
91 | } | |
92 | EXPORT_SYMBOL(nf_unregister_hook); | |
93 | ||
972d1cb1 PM |
94 | int nf_register_hooks(struct nf_hook_ops *reg, unsigned int n) |
95 | { | |
96 | unsigned int i; | |
97 | int err = 0; | |
98 | ||
99 | for (i = 0; i < n; i++) { | |
100 | err = nf_register_hook(®[i]); | |
101 | if (err) | |
102 | goto err; | |
103 | } | |
104 | return err; | |
105 | ||
106 | err: | |
107 | if (i > 0) | |
108 | nf_unregister_hooks(reg, i); | |
109 | return err; | |
110 | } | |
111 | EXPORT_SYMBOL(nf_register_hooks); | |
112 | ||
113 | void nf_unregister_hooks(struct nf_hook_ops *reg, unsigned int n) | |
114 | { | |
115 | unsigned int i; | |
116 | ||
117 | for (i = 0; i < n; i++) | |
118 | nf_unregister_hook(®[i]); | |
119 | } | |
120 | EXPORT_SYMBOL(nf_unregister_hooks); | |
121 | ||
f6ebe77f HW |
122 | unsigned int nf_iterate(struct list_head *head, |
123 | struct sk_buff **skb, | |
124 | int hook, | |
125 | const struct net_device *indev, | |
126 | const struct net_device *outdev, | |
127 | struct list_head **i, | |
128 | int (*okfn)(struct sk_buff *), | |
129 | int hook_thresh) | |
130 | { | |
131 | unsigned int verdict; | |
132 | ||
133 | /* | |
134 | * The caller must not block between calls to this | |
135 | * function because of risk of continuing from deleted element. | |
136 | */ | |
137 | list_for_each_continue_rcu(*i, head) { | |
138 | struct nf_hook_ops *elem = (struct nf_hook_ops *)*i; | |
139 | ||
140 | if (hook_thresh > elem->priority) | |
141 | continue; | |
142 | ||
143 | /* Optimization: we don't need to hold module | |
601e68e1 | 144 | reference here, since function can't sleep. --RR */ |
f6ebe77f HW |
145 | verdict = elem->hook(hook, skb, indev, outdev, okfn); |
146 | if (verdict != NF_ACCEPT) { | |
147 | #ifdef CONFIG_NETFILTER_DEBUG | |
148 | if (unlikely((verdict & NF_VERDICT_MASK) | |
149 | > NF_MAX_VERDICT)) { | |
150 | NFDEBUG("Evil return from %p(%u).\n", | |
601e68e1 | 151 | elem->hook, hook); |
f6ebe77f HW |
152 | continue; |
153 | } | |
154 | #endif | |
155 | if (verdict != NF_REPEAT) | |
156 | return verdict; | |
157 | *i = (*i)->prev; | |
158 | } | |
159 | } | |
160 | return NF_ACCEPT; | |
161 | } | |
162 | ||
163 | ||
164 | /* Returns 1 if okfn() needs to be executed by the caller, | |
165 | * -EPERM for NF_DROP, 0 otherwise. */ | |
166 | int nf_hook_slow(int pf, unsigned int hook, struct sk_buff **pskb, | |
167 | struct net_device *indev, | |
168 | struct net_device *outdev, | |
169 | int (*okfn)(struct sk_buff *), | |
170 | int hook_thresh) | |
171 | { | |
172 | struct list_head *elem; | |
173 | unsigned int verdict; | |
174 | int ret = 0; | |
175 | ||
176 | /* We may already have this, but read-locks nest anyway */ | |
177 | rcu_read_lock(); | |
178 | ||
179 | elem = &nf_hooks[pf][hook]; | |
180 | next_hook: | |
181 | verdict = nf_iterate(&nf_hooks[pf][hook], pskb, hook, indev, | |
182 | outdev, &elem, okfn, hook_thresh); | |
183 | if (verdict == NF_ACCEPT || verdict == NF_STOP) { | |
184 | ret = 1; | |
185 | goto unlock; | |
186 | } else if (verdict == NF_DROP) { | |
187 | kfree_skb(*pskb); | |
188 | ret = -EPERM; | |
189 | } else if ((verdict & NF_VERDICT_MASK) == NF_QUEUE) { | |
190 | NFDEBUG("nf_hook: Verdict = QUEUE.\n"); | |
394f545d | 191 | if (!nf_queue(*pskb, elem, pf, hook, indev, outdev, okfn, |
f6ebe77f HW |
192 | verdict >> NF_VERDICT_BITS)) |
193 | goto next_hook; | |
194 | } | |
195 | unlock: | |
196 | rcu_read_unlock(); | |
197 | return ret; | |
198 | } | |
199 | EXPORT_SYMBOL(nf_hook_slow); | |
200 | ||
201 | ||
202 | int skb_make_writable(struct sk_buff **pskb, unsigned int writable_len) | |
203 | { | |
204 | struct sk_buff *nskb; | |
205 | ||
206 | if (writable_len > (*pskb)->len) | |
207 | return 0; | |
208 | ||
209 | /* Not exclusive use of packet? Must copy. */ | |
210 | if (skb_shared(*pskb) || skb_cloned(*pskb)) | |
211 | goto copy_skb; | |
212 | ||
213 | return pskb_may_pull(*pskb, writable_len); | |
214 | ||
215 | copy_skb: | |
216 | nskb = skb_copy(*pskb, GFP_ATOMIC); | |
217 | if (!nskb) | |
218 | return 0; | |
219 | BUG_ON(skb_is_nonlinear(nskb)); | |
220 | ||
221 | /* Rest of kernel will get very unhappy if we pass it a | |
222 | suddenly-orphaned skbuff */ | |
223 | if ((*pskb)->sk) | |
224 | skb_set_owner_w(nskb, (*pskb)->sk); | |
225 | kfree_skb(*pskb); | |
226 | *pskb = nskb; | |
227 | return 1; | |
228 | } | |
229 | EXPORT_SYMBOL(skb_make_writable); | |
230 | ||
43bc0ca7 AV |
231 | void nf_proto_csum_replace4(__sum16 *sum, struct sk_buff *skb, |
232 | __be32 from, __be32 to, int pseudohdr) | |
4cf411de | 233 | { |
43bc0ca7 | 234 | __be32 diff[] = { ~from, to }; |
4cf411de | 235 | if (skb->ip_summed != CHECKSUM_PARTIAL) { |
43bc0ca7 AV |
236 | *sum = csum_fold(csum_partial((char *)diff, sizeof(diff), |
237 | ~csum_unfold(*sum))); | |
4cf411de | 238 | if (skb->ip_summed == CHECKSUM_COMPLETE && pseudohdr) |
43bc0ca7 AV |
239 | skb->csum = ~csum_partial((char *)diff, sizeof(diff), |
240 | ~skb->csum); | |
4cf411de | 241 | } else if (pseudohdr) |
43bc0ca7 AV |
242 | *sum = ~csum_fold(csum_partial((char *)diff, sizeof(diff), |
243 | csum_unfold(*sum))); | |
4cf411de | 244 | } |
43bc0ca7 | 245 | EXPORT_SYMBOL(nf_proto_csum_replace4); |
f6ebe77f HW |
246 | |
247 | /* This does not belong here, but locally generated errors need it if connection | |
248 | tracking in use: without this, connection may not be in hash table, and hence | |
249 | manufactured ICMP or RST packets will not be associated with it. */ | |
250 | void (*ip_ct_attach)(struct sk_buff *, struct sk_buff *); | |
251 | EXPORT_SYMBOL(ip_ct_attach); | |
252 | ||
253 | void nf_ct_attach(struct sk_buff *new, struct sk_buff *skb) | |
254 | { | |
255 | void (*attach)(struct sk_buff *, struct sk_buff *); | |
256 | ||
c3a47ab3 PM |
257 | if (skb->nfct) { |
258 | rcu_read_lock(); | |
259 | attach = rcu_dereference(ip_ct_attach); | |
260 | if (attach) | |
261 | attach(new, skb); | |
262 | rcu_read_unlock(); | |
f6ebe77f HW |
263 | } |
264 | } | |
265 | EXPORT_SYMBOL(nf_ct_attach); | |
266 | ||
267 | #ifdef CONFIG_PROC_FS | |
268 | struct proc_dir_entry *proc_net_netfilter; | |
269 | EXPORT_SYMBOL(proc_net_netfilter); | |
270 | #endif | |
271 | ||
272 | void __init netfilter_init(void) | |
273 | { | |
274 | int i, h; | |
275 | for (i = 0; i < NPROTO; i++) { | |
276 | for (h = 0; h < NF_MAX_HOOKS; h++) | |
277 | INIT_LIST_HEAD(&nf_hooks[i][h]); | |
278 | } | |
279 | ||
280 | #ifdef CONFIG_PROC_FS | |
281 | proc_net_netfilter = proc_mkdir("netfilter", proc_net); | |
282 | if (!proc_net_netfilter) | |
283 | panic("cannot create netfilter proc entry"); | |
284 | #endif | |
285 | ||
286 | if (netfilter_queue_init() < 0) | |
287 | panic("cannot initialize nf_queue"); | |
288 | if (netfilter_log_init() < 0) | |
289 | panic("cannot initialize nf_log"); | |
290 | } |