Version:  2.0.40 2.2.26 2.4.37 3.3 3.4 3.5 3.6 3.7 3.8 3.9 3.10 3.11 3.12 3.13 3.14 3.15 3.16 3.17 3.18 3.19

Linux/net/netfilter/core.c

  1 /* netfilter.c: look after the filters for various protocols.
  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  * Patrick McHardy (c) 2006-2012
  9  */
 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>
 18 #include <linux/if.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>
 26 #include <net/sock.h>
 27 
 28 #include "nf_internals.h"
 29 
 30 static DEFINE_MUTEX(afinfo_mutex);
 31 
 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);
 36 
 37 int nf_register_afinfo(const struct nf_afinfo *afinfo)
 38 {
 39         mutex_lock(&afinfo_mutex);
 40         RCU_INIT_POINTER(nf_afinfo[afinfo->family], afinfo);
 41         mutex_unlock(&afinfo_mutex);
 42         return 0;
 43 }
 44 EXPORT_SYMBOL_GPL(nf_register_afinfo);
 45 
 46 void nf_unregister_afinfo(const struct nf_afinfo *afinfo)
 47 {
 48         mutex_lock(&afinfo_mutex);
 49         RCU_INIT_POINTER(nf_afinfo[afinfo->family], NULL);
 50         mutex_unlock(&afinfo_mutex);
 51         synchronize_rcu();
 52 }
 53 EXPORT_SYMBOL_GPL(nf_unregister_afinfo);
 54 
 55 struct list_head nf_hooks[NFPROTO_NUMPROTO][NF_MAX_HOOKS] __read_mostly;
 56 EXPORT_SYMBOL(nf_hooks);
 57 
 58 #ifdef HAVE_JUMP_LABEL
 59 struct static_key nf_hooks_needed[NFPROTO_NUMPROTO][NF_MAX_HOOKS];
 60 EXPORT_SYMBOL(nf_hooks_needed);
 61 #endif
 62 
 63 static DEFINE_MUTEX(nf_hook_mutex);
 64 
 65 int nf_register_hook(struct nf_hook_ops *reg)
 66 {
 67         struct nf_hook_ops *elem;
 68 
 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)
 72                         break;
 73         }
 74         list_add_rcu(&reg->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]);
 78 #endif
 79         return 0;
 80 }
 81 EXPORT_SYMBOL(nf_register_hook);
 82 
 83 void nf_unregister_hook(struct nf_hook_ops *reg)
 84 {
 85         mutex_lock(&nf_hook_mutex);
 86         list_del_rcu(&reg->list);
 87         mutex_unlock(&nf_hook_mutex);
 88 #ifdef HAVE_JUMP_LABEL
 89         static_key_slow_dec(&nf_hooks_needed[reg->pf][reg->hooknum]);
 90 #endif
 91         synchronize_net();
 92 }
 93 EXPORT_SYMBOL(nf_unregister_hook);
 94 
 95 int nf_register_hooks(struct nf_hook_ops *reg, unsigned int n)
 96 {
 97         unsigned int i;
 98         int err = 0;
 99 
100         for (i = 0; i < n; i++) {
101                 err = nf_register_hook(&reg[i]);
102                 if (err)
103                         goto err;
104         }
105         return err;
106 
107 err:
108         if (i > 0)
109                 nf_unregister_hooks(reg, i);
110         return err;
111 }
112 EXPORT_SYMBOL(nf_register_hooks);
113 
114 void nf_unregister_hooks(struct nf_hook_ops *reg, unsigned int n)
115 {
116         while (n-- > 0)
117                 nf_unregister_hook(&reg[n]);
118 }
119 EXPORT_SYMBOL(nf_unregister_hooks);
120 
121 unsigned int nf_iterate(struct list_head *head,
122                         struct sk_buff *skb,
123                         unsigned int hook,
124                         const struct net_device *indev,
125                         const struct net_device *outdev,
126                         struct nf_hook_ops **elemp,
127                         int (*okfn)(struct sk_buff *),
128                         int hook_thresh)
129 {
130         unsigned int verdict;
131 
132         /*
133          * The caller must not block between calls to this
134          * function because of risk of continuing from deleted element.
135          */
136         list_for_each_entry_continue_rcu((*elemp), head, list) {
137                 if (hook_thresh > (*elemp)->priority)
138                         continue;
139 
140                 /* Optimization: we don't need to hold module
141                    reference here, since function can't sleep. --RR */
142 repeat:
143                 verdict = (*elemp)->hook(*elemp, skb, indev, outdev, okfn);
144                 if (verdict != NF_ACCEPT) {
145 #ifdef CONFIG_NETFILTER_DEBUG
146                         if (unlikely((verdict & NF_VERDICT_MASK)
147                                                         > NF_MAX_VERDICT)) {
148                                 NFDEBUG("Evil return from %p(%u).\n",
149                                         (*elemp)->hook, hook);
150                                 continue;
151                         }
152 #endif
153                         if (verdict != NF_REPEAT)
154                                 return verdict;
155                         goto repeat;
156                 }
157         }
158         return NF_ACCEPT;
159 }
160 
161 
162 /* Returns 1 if okfn() needs to be executed by the caller,
163  * -EPERM for NF_DROP, 0 otherwise. */
164 int nf_hook_slow(u_int8_t pf, unsigned int hook, struct sk_buff *skb,
165                  struct net_device *indev,
166                  struct net_device *outdev,
167                  int (*okfn)(struct sk_buff *),
168                  int hook_thresh)
169 {
170         struct nf_hook_ops *elem;
171         unsigned int verdict;
172         int ret = 0;
173 
174         /* We may already have this, but read-locks nest anyway */
175         rcu_read_lock();
176 
177         elem = list_entry_rcu(&nf_hooks[pf][hook], struct nf_hook_ops, list);
178 next_hook:
179         verdict = nf_iterate(&nf_hooks[pf][hook], skb, hook, indev,
180                              outdev, &elem, okfn, hook_thresh);
181         if (verdict == NF_ACCEPT || verdict == NF_STOP) {
182                 ret = 1;
183         } else if ((verdict & NF_VERDICT_MASK) == NF_DROP) {
184                 kfree_skb(skb);
185                 ret = NF_DROP_GETERR(verdict);
186                 if (ret == 0)
187                         ret = -EPERM;
188         } else if ((verdict & NF_VERDICT_MASK) == NF_QUEUE) {
189                 int err = nf_queue(skb, elem, pf, hook, indev, outdev, okfn,
190                                                 verdict >> NF_VERDICT_QBITS);
191                 if (err < 0) {
192                         if (err == -ECANCELED)
193                                 goto next_hook;
194                         if (err == -ESRCH &&
195                            (verdict & NF_VERDICT_FLAG_QUEUE_BYPASS))
196                                 goto next_hook;
197                         kfree_skb(skb);
198                 }
199         }
200         rcu_read_unlock();
201         return ret;
202 }
203 EXPORT_SYMBOL(nf_hook_slow);
204 
205 
206 int skb_make_writable(struct sk_buff *skb, unsigned int writable_len)
207 {
208         if (writable_len > skb->len)
209                 return 0;
210 
211         /* Not exclusive use of packet?  Must copy. */
212         if (!skb_cloned(skb)) {
213                 if (writable_len <= skb_headlen(skb))
214                         return 1;
215         } else if (skb_clone_writable(skb, writable_len))
216                 return 1;
217 
218         if (writable_len <= skb_headlen(skb))
219                 writable_len = 0;
220         else
221                 writable_len -= skb_headlen(skb);
222 
223         return !!__pskb_pull_tail(skb, writable_len);
224 }
225 EXPORT_SYMBOL(skb_make_writable);
226 
227 #if IS_ENABLED(CONFIG_NF_CONNTRACK)
228 /* This does not belong here, but locally generated errors need it if connection
229    tracking in use: without this, connection may not be in hash table, and hence
230    manufactured ICMP or RST packets will not be associated with it. */
231 void (*ip_ct_attach)(struct sk_buff *, const struct sk_buff *)
232                 __rcu __read_mostly;
233 EXPORT_SYMBOL(ip_ct_attach);
234 
235 void nf_ct_attach(struct sk_buff *new, const struct sk_buff *skb)
236 {
237         void (*attach)(struct sk_buff *, const struct sk_buff *);
238 
239         if (skb->nfct) {
240                 rcu_read_lock();
241                 attach = rcu_dereference(ip_ct_attach);
242                 if (attach)
243                         attach(new, skb);
244                 rcu_read_unlock();
245         }
246 }
247 EXPORT_SYMBOL(nf_ct_attach);
248 
249 void (*nf_ct_destroy)(struct nf_conntrack *) __rcu __read_mostly;
250 EXPORT_SYMBOL(nf_ct_destroy);
251 
252 void nf_conntrack_destroy(struct nf_conntrack *nfct)
253 {
254         void (*destroy)(struct nf_conntrack *);
255 
256         rcu_read_lock();
257         destroy = rcu_dereference(nf_ct_destroy);
258         BUG_ON(destroy == NULL);
259         destroy(nfct);
260         rcu_read_unlock();
261 }
262 EXPORT_SYMBOL(nf_conntrack_destroy);
263 
264 struct nfq_ct_hook __rcu *nfq_ct_hook __read_mostly;
265 EXPORT_SYMBOL_GPL(nfq_ct_hook);
266 
267 struct nfq_ct_nat_hook __rcu *nfq_ct_nat_hook __read_mostly;
268 EXPORT_SYMBOL_GPL(nfq_ct_nat_hook);
269 
270 #endif /* CONFIG_NF_CONNTRACK */
271 
272 #ifdef CONFIG_NF_NAT_NEEDED
273 void (*nf_nat_decode_session_hook)(struct sk_buff *, struct flowi *);
274 EXPORT_SYMBOL(nf_nat_decode_session_hook);
275 #endif
276 
277 static int __net_init netfilter_net_init(struct net *net)
278 {
279 #ifdef CONFIG_PROC_FS
280         net->nf.proc_netfilter = proc_net_mkdir(net, "netfilter",
281                                                 net->proc_net);
282         if (!net->nf.proc_netfilter) {
283                 if (!net_eq(net, &init_net))
284                         pr_err("cannot create netfilter proc entry");
285 
286                 return -ENOMEM;
287         }
288 #endif
289         return 0;
290 }
291 
292 static void __net_exit netfilter_net_exit(struct net *net)
293 {
294         remove_proc_entry("netfilter", net->proc_net);
295 }
296 
297 static struct pernet_operations netfilter_net_ops = {
298         .init = netfilter_net_init,
299         .exit = netfilter_net_exit,
300 };
301 
302 int __init netfilter_init(void)
303 {
304         int i, h, ret;
305 
306         for (i = 0; i < ARRAY_SIZE(nf_hooks); i++) {
307                 for (h = 0; h < NF_MAX_HOOKS; h++)
308                         INIT_LIST_HEAD(&nf_hooks[i][h]);
309         }
310 
311         ret = register_pernet_subsys(&netfilter_net_ops);
312         if (ret < 0)
313                 goto err;
314 
315         ret = netfilter_log_init();
316         if (ret < 0)
317                 goto err_pernet;
318 
319         return 0;
320 err_pernet:
321         unregister_pernet_subsys(&netfilter_net_ops);
322 err:
323         return ret;
324 }
325 

This page was automatically generated by LXR 0.3.1 (source).  •  Linux is a registered trademark of Linus Torvalds  •  Contact us