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Linux/net/netfilter/nfnetlink_cttimeout.c

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  1 /*
  2  * (C) 2012 by Pablo Neira Ayuso <pablo@netfilter.org>
  3  * (C) 2012 by Vyatta Inc. <http://www.vyatta.com>
  4  *
  5  * This program is free software; you can redistribute it and/or modify
  6  * it under the terms of the GNU General Public License version 2 as
  7  * published by the Free Software Foundation (or any later at your option).
  8  */
  9 #include <linux/init.h>
 10 #include <linux/module.h>
 11 #include <linux/kernel.h>
 12 #include <linux/rculist.h>
 13 #include <linux/rculist_nulls.h>
 14 #include <linux/types.h>
 15 #include <linux/timer.h>
 16 #include <linux/security.h>
 17 #include <linux/skbuff.h>
 18 #include <linux/errno.h>
 19 #include <linux/netlink.h>
 20 #include <linux/spinlock.h>
 21 #include <linux/interrupt.h>
 22 #include <linux/slab.h>
 23 
 24 #include <linux/netfilter.h>
 25 #include <net/netlink.h>
 26 #include <net/sock.h>
 27 #include <net/netfilter/nf_conntrack.h>
 28 #include <net/netfilter/nf_conntrack_core.h>
 29 #include <net/netfilter/nf_conntrack_l3proto.h>
 30 #include <net/netfilter/nf_conntrack_l4proto.h>
 31 #include <net/netfilter/nf_conntrack_tuple.h>
 32 #include <net/netfilter/nf_conntrack_timeout.h>
 33 
 34 #include <linux/netfilter/nfnetlink.h>
 35 #include <linux/netfilter/nfnetlink_cttimeout.h>
 36 
 37 MODULE_LICENSE("GPL");
 38 MODULE_AUTHOR("Pablo Neira Ayuso <pablo@netfilter.org>");
 39 MODULE_DESCRIPTION("cttimeout: Extended Netfilter Connection Tracking timeout tuning");
 40 
 41 static LIST_HEAD(cttimeout_list);
 42 
 43 static const struct nla_policy cttimeout_nla_policy[CTA_TIMEOUT_MAX+1] = {
 44         [CTA_TIMEOUT_NAME]      = { .type = NLA_NUL_STRING,
 45                                     .len  = CTNL_TIMEOUT_NAME_MAX - 1},
 46         [CTA_TIMEOUT_L3PROTO]   = { .type = NLA_U16 },
 47         [CTA_TIMEOUT_L4PROTO]   = { .type = NLA_U8 },
 48         [CTA_TIMEOUT_DATA]      = { .type = NLA_NESTED },
 49 };
 50 
 51 static int
 52 ctnl_timeout_parse_policy(struct ctnl_timeout *timeout,
 53                           struct nf_conntrack_l4proto *l4proto,
 54                           struct net *net,
 55                           const struct nlattr *attr)
 56 {
 57         int ret = 0;
 58 
 59         if (likely(l4proto->ctnl_timeout.nlattr_to_obj)) {
 60                 struct nlattr *tb[l4proto->ctnl_timeout.nlattr_max+1];
 61 
 62                 nla_parse_nested(tb, l4proto->ctnl_timeout.nlattr_max,
 63                                  attr, l4proto->ctnl_timeout.nla_policy);
 64 
 65                 ret = l4proto->ctnl_timeout.nlattr_to_obj(tb, net,
 66                                                           &timeout->data);
 67         }
 68         return ret;
 69 }
 70 
 71 static int
 72 cttimeout_new_timeout(struct sock *ctnl, struct sk_buff *skb,
 73                       const struct nlmsghdr *nlh,
 74                       const struct nlattr * const cda[])
 75 {
 76         __u16 l3num;
 77         __u8 l4num;
 78         struct nf_conntrack_l4proto *l4proto;
 79         struct ctnl_timeout *timeout, *matching = NULL;
 80         struct net *net = sock_net(skb->sk);
 81         char *name;
 82         int ret;
 83 
 84         if (!cda[CTA_TIMEOUT_NAME] ||
 85             !cda[CTA_TIMEOUT_L3PROTO] ||
 86             !cda[CTA_TIMEOUT_L4PROTO] ||
 87             !cda[CTA_TIMEOUT_DATA])
 88                 return -EINVAL;
 89 
 90         name = nla_data(cda[CTA_TIMEOUT_NAME]);
 91         l3num = ntohs(nla_get_be16(cda[CTA_TIMEOUT_L3PROTO]));
 92         l4num = nla_get_u8(cda[CTA_TIMEOUT_L4PROTO]);
 93 
 94         list_for_each_entry(timeout, &cttimeout_list, head) {
 95                 if (strncmp(timeout->name, name, CTNL_TIMEOUT_NAME_MAX) != 0)
 96                         continue;
 97 
 98                 if (nlh->nlmsg_flags & NLM_F_EXCL)
 99                         return -EEXIST;
100 
101                 matching = timeout;
102                 break;
103         }
104 
105         l4proto = nf_ct_l4proto_find_get(l3num, l4num);
106 
107         /* This protocol is not supportted, skip. */
108         if (l4proto->l4proto != l4num) {
109                 ret = -EOPNOTSUPP;
110                 goto err_proto_put;
111         }
112 
113         if (matching) {
114                 if (nlh->nlmsg_flags & NLM_F_REPLACE) {
115                         /* You cannot replace one timeout policy by another of
116                          * different kind, sorry.
117                          */
118                         if (matching->l3num != l3num ||
119                             matching->l4proto->l4proto != l4num) {
120                                 ret = -EINVAL;
121                                 goto err_proto_put;
122                         }
123 
124                         ret = ctnl_timeout_parse_policy(matching, l4proto, net,
125                                                         cda[CTA_TIMEOUT_DATA]);
126                         return ret;
127                 }
128                 ret = -EBUSY;
129                 goto err_proto_put;
130         }
131 
132         timeout = kzalloc(sizeof(struct ctnl_timeout) +
133                           l4proto->ctnl_timeout.obj_size, GFP_KERNEL);
134         if (timeout == NULL) {
135                 ret = -ENOMEM;
136                 goto err_proto_put;
137         }
138 
139         ret = ctnl_timeout_parse_policy(timeout, l4proto, net,
140                                         cda[CTA_TIMEOUT_DATA]);
141         if (ret < 0)
142                 goto err;
143 
144         strcpy(timeout->name, nla_data(cda[CTA_TIMEOUT_NAME]));
145         timeout->l3num = l3num;
146         timeout->l4proto = l4proto;
147         atomic_set(&timeout->refcnt, 1);
148         list_add_tail_rcu(&timeout->head, &cttimeout_list);
149 
150         return 0;
151 err:
152         kfree(timeout);
153 err_proto_put:
154         nf_ct_l4proto_put(l4proto);
155         return ret;
156 }
157 
158 static int
159 ctnl_timeout_fill_info(struct sk_buff *skb, u32 portid, u32 seq, u32 type,
160                        int event, struct ctnl_timeout *timeout)
161 {
162         struct nlmsghdr *nlh;
163         struct nfgenmsg *nfmsg;
164         unsigned int flags = portid ? NLM_F_MULTI : 0;
165         struct nf_conntrack_l4proto *l4proto = timeout->l4proto;
166 
167         event |= NFNL_SUBSYS_CTNETLINK_TIMEOUT << 8;
168         nlh = nlmsg_put(skb, portid, seq, event, sizeof(*nfmsg), flags);
169         if (nlh == NULL)
170                 goto nlmsg_failure;
171 
172         nfmsg = nlmsg_data(nlh);
173         nfmsg->nfgen_family = AF_UNSPEC;
174         nfmsg->version = NFNETLINK_V0;
175         nfmsg->res_id = 0;
176 
177         if (nla_put_string(skb, CTA_TIMEOUT_NAME, timeout->name) ||
178             nla_put_be16(skb, CTA_TIMEOUT_L3PROTO, htons(timeout->l3num)) ||
179             nla_put_u8(skb, CTA_TIMEOUT_L4PROTO, timeout->l4proto->l4proto) ||
180             nla_put_be32(skb, CTA_TIMEOUT_USE,
181                          htonl(atomic_read(&timeout->refcnt))))
182                 goto nla_put_failure;
183 
184         if (likely(l4proto->ctnl_timeout.obj_to_nlattr)) {
185                 struct nlattr *nest_parms;
186                 int ret;
187 
188                 nest_parms = nla_nest_start(skb,
189                                             CTA_TIMEOUT_DATA | NLA_F_NESTED);
190                 if (!nest_parms)
191                         goto nla_put_failure;
192 
193                 ret = l4proto->ctnl_timeout.obj_to_nlattr(skb, &timeout->data);
194                 if (ret < 0)
195                         goto nla_put_failure;
196 
197                 nla_nest_end(skb, nest_parms);
198         }
199 
200         nlmsg_end(skb, nlh);
201         return skb->len;
202 
203 nlmsg_failure:
204 nla_put_failure:
205         nlmsg_cancel(skb, nlh);
206         return -1;
207 }
208 
209 static int
210 ctnl_timeout_dump(struct sk_buff *skb, struct netlink_callback *cb)
211 {
212         struct ctnl_timeout *cur, *last;
213 
214         if (cb->args[2])
215                 return 0;
216 
217         last = (struct ctnl_timeout *)cb->args[1];
218         if (cb->args[1])
219                 cb->args[1] = 0;
220 
221         rcu_read_lock();
222         list_for_each_entry_rcu(cur, &cttimeout_list, head) {
223                 if (last && cur != last)
224                         continue;
225 
226                 if (ctnl_timeout_fill_info(skb, NETLINK_CB(cb->skb).portid,
227                                            cb->nlh->nlmsg_seq,
228                                            NFNL_MSG_TYPE(cb->nlh->nlmsg_type),
229                                            IPCTNL_MSG_TIMEOUT_NEW, cur) < 0) {
230                         cb->args[1] = (unsigned long)cur;
231                         break;
232                 }
233         }
234         if (!cb->args[1])
235                 cb->args[2] = 1;
236         rcu_read_unlock();
237         return skb->len;
238 }
239 
240 static int
241 cttimeout_get_timeout(struct sock *ctnl, struct sk_buff *skb,
242                       const struct nlmsghdr *nlh,
243                       const struct nlattr * const cda[])
244 {
245         int ret = -ENOENT;
246         char *name;
247         struct ctnl_timeout *cur;
248 
249         if (nlh->nlmsg_flags & NLM_F_DUMP) {
250                 struct netlink_dump_control c = {
251                         .dump = ctnl_timeout_dump,
252                 };
253                 return netlink_dump_start(ctnl, skb, nlh, &c);
254         }
255 
256         if (!cda[CTA_TIMEOUT_NAME])
257                 return -EINVAL;
258         name = nla_data(cda[CTA_TIMEOUT_NAME]);
259 
260         list_for_each_entry(cur, &cttimeout_list, head) {
261                 struct sk_buff *skb2;
262 
263                 if (strncmp(cur->name, name, CTNL_TIMEOUT_NAME_MAX) != 0)
264                         continue;
265 
266                 skb2 = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
267                 if (skb2 == NULL) {
268                         ret = -ENOMEM;
269                         break;
270                 }
271 
272                 ret = ctnl_timeout_fill_info(skb2, NETLINK_CB(skb).portid,
273                                              nlh->nlmsg_seq,
274                                              NFNL_MSG_TYPE(nlh->nlmsg_type),
275                                              IPCTNL_MSG_TIMEOUT_NEW, cur);
276                 if (ret <= 0) {
277                         kfree_skb(skb2);
278                         break;
279                 }
280                 ret = netlink_unicast(ctnl, skb2, NETLINK_CB(skb).portid,
281                                         MSG_DONTWAIT);
282                 if (ret > 0)
283                         ret = 0;
284 
285                 /* this avoids a loop in nfnetlink. */
286                 return ret == -EAGAIN ? -ENOBUFS : ret;
287         }
288         return ret;
289 }
290 
291 /* try to delete object, fail if it is still in use. */
292 static int ctnl_timeout_try_del(struct ctnl_timeout *timeout)
293 {
294         int ret = 0;
295 
296         /* we want to avoid races with nf_ct_timeout_find_get. */
297         if (atomic_dec_and_test(&timeout->refcnt)) {
298                 /* We are protected by nfnl mutex. */
299                 list_del_rcu(&timeout->head);
300                 nf_ct_l4proto_put(timeout->l4proto);
301                 kfree_rcu(timeout, rcu_head);
302         } else {
303                 /* still in use, restore reference counter. */
304                 atomic_inc(&timeout->refcnt);
305                 ret = -EBUSY;
306         }
307         return ret;
308 }
309 
310 static int
311 cttimeout_del_timeout(struct sock *ctnl, struct sk_buff *skb,
312                       const struct nlmsghdr *nlh,
313                       const struct nlattr * const cda[])
314 {
315         char *name;
316         struct ctnl_timeout *cur;
317         int ret = -ENOENT;
318 
319         if (!cda[CTA_TIMEOUT_NAME]) {
320                 list_for_each_entry(cur, &cttimeout_list, head)
321                         ctnl_timeout_try_del(cur);
322 
323                 return 0;
324         }
325         name = nla_data(cda[CTA_TIMEOUT_NAME]);
326 
327         list_for_each_entry(cur, &cttimeout_list, head) {
328                 if (strncmp(cur->name, name, CTNL_TIMEOUT_NAME_MAX) != 0)
329                         continue;
330 
331                 ret = ctnl_timeout_try_del(cur);
332                 if (ret < 0)
333                         return ret;
334 
335                 break;
336         }
337         return ret;
338 }
339 
340 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT
341 static struct ctnl_timeout *ctnl_timeout_find_get(const char *name)
342 {
343         struct ctnl_timeout *timeout, *matching = NULL;
344 
345         rcu_read_lock();
346         list_for_each_entry_rcu(timeout, &cttimeout_list, head) {
347                 if (strncmp(timeout->name, name, CTNL_TIMEOUT_NAME_MAX) != 0)
348                         continue;
349 
350                 if (!try_module_get(THIS_MODULE))
351                         goto err;
352 
353                 if (!atomic_inc_not_zero(&timeout->refcnt)) {
354                         module_put(THIS_MODULE);
355                         goto err;
356                 }
357                 matching = timeout;
358                 break;
359         }
360 err:
361         rcu_read_unlock();
362         return matching;
363 }
364 
365 static void ctnl_timeout_put(struct ctnl_timeout *timeout)
366 {
367         atomic_dec(&timeout->refcnt);
368         module_put(THIS_MODULE);
369 }
370 #endif /* CONFIG_NF_CONNTRACK_TIMEOUT */
371 
372 static const struct nfnl_callback cttimeout_cb[IPCTNL_MSG_TIMEOUT_MAX] = {
373         [IPCTNL_MSG_TIMEOUT_NEW]        = { .call = cttimeout_new_timeout,
374                                             .attr_count = CTA_TIMEOUT_MAX,
375                                             .policy = cttimeout_nla_policy },
376         [IPCTNL_MSG_TIMEOUT_GET]        = { .call = cttimeout_get_timeout,
377                                             .attr_count = CTA_TIMEOUT_MAX,
378                                             .policy = cttimeout_nla_policy },
379         [IPCTNL_MSG_TIMEOUT_DELETE]     = { .call = cttimeout_del_timeout,
380                                             .attr_count = CTA_TIMEOUT_MAX,
381                                             .policy = cttimeout_nla_policy },
382 };
383 
384 static const struct nfnetlink_subsystem cttimeout_subsys = {
385         .name                           = "conntrack_timeout",
386         .subsys_id                      = NFNL_SUBSYS_CTNETLINK_TIMEOUT,
387         .cb_count                       = IPCTNL_MSG_TIMEOUT_MAX,
388         .cb                             = cttimeout_cb,
389 };
390 
391 MODULE_ALIAS_NFNL_SUBSYS(NFNL_SUBSYS_CTNETLINK_TIMEOUT);
392 
393 static int __init cttimeout_init(void)
394 {
395         int ret;
396 
397         ret = nfnetlink_subsys_register(&cttimeout_subsys);
398         if (ret < 0) {
399                 pr_err("cttimeout_init: cannot register cttimeout with "
400                         "nfnetlink.\n");
401                 goto err_out;
402         }
403 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT
404         RCU_INIT_POINTER(nf_ct_timeout_find_get_hook, ctnl_timeout_find_get);
405         RCU_INIT_POINTER(nf_ct_timeout_put_hook, ctnl_timeout_put);
406 #endif /* CONFIG_NF_CONNTRACK_TIMEOUT */
407         return 0;
408 
409 err_out:
410         return ret;
411 }
412 
413 static void __exit cttimeout_exit(void)
414 {
415         struct ctnl_timeout *cur, *tmp;
416 
417         pr_info("cttimeout: unregistering from nfnetlink.\n");
418 
419         nfnetlink_subsys_unregister(&cttimeout_subsys);
420         list_for_each_entry_safe(cur, tmp, &cttimeout_list, head) {
421                 list_del_rcu(&cur->head);
422                 /* We are sure that our objects have no clients at this point,
423                  * it's safe to release them all without checking refcnt.
424                  */
425                 nf_ct_l4proto_put(cur->l4proto);
426                 kfree_rcu(cur, rcu_head);
427         }
428 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT
429         RCU_INIT_POINTER(nf_ct_timeout_find_get_hook, NULL);
430         RCU_INIT_POINTER(nf_ct_timeout_put_hook, NULL);
431 #endif /* CONFIG_NF_CONNTRACK_TIMEOUT */
432 }
433 
434 module_init(cttimeout_init);
435 module_exit(cttimeout_exit);
436 

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