net/netfilter/nfnetlink_cttimeout.c

   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                 ret = nla_parse_nested(tb, l4proto->ctnl_timeout.nlattr_max,
  63                                        attr, l4proto->ctnl_timeout.nla_policy);
  64                 if (ret < 0)
  65                         return ret;
  66
  67                 ret = l4proto->ctnl_timeout.nlattr_to_obj(tb, net,
  68                                                           &timeout->data);
  69         }
  70         return ret;
  71 }
  72
  73 static int
  74 cttimeout_new_timeout(struct sock *ctnl, struct sk_buff *skb,
  75                       const struct nlmsghdr *nlh,
  76                       const struct nlattr * const cda[])
  77 {
  78         __u16 l3num;
  79         __u8 l4num;
  80         struct nf_conntrack_l4proto *l4proto;
  81         struct ctnl_timeout *timeout, *matching = NULL;
  82         struct net *net = sock_net(skb->sk);
  83         char *name;
  84         int ret;
  85
  86         if (!cda[CTA_TIMEOUT_NAME] ||
  87             !cda[CTA_TIMEOUT_L3PROTO] ||
  88             !cda[CTA_TIMEOUT_L4PROTO] ||
  89             !cda[CTA_TIMEOUT_DATA])
  90                 return -EINVAL;
  91
  92         name = nla_data(cda[CTA_TIMEOUT_NAME]);
  93         l3num = ntohs(nla_get_be16(cda[CTA_TIMEOUT_L3PROTO]));
  94         l4num = nla_get_u8(cda[CTA_TIMEOUT_L4PROTO]);
  95
  96         list_for_each_entry(timeout, &cttimeout_list, head) {
  97                 if (strncmp(timeout->name, name, CTNL_TIMEOUT_NAME_MAX) != 0)
  98                         continue;
  99
 100                 if (nlh->nlmsg_flags & NLM_F_EXCL)
 101                         return -EEXIST;
 102
 103                 matching = timeout;
 104                 break;
 105         }
 106
 107         l4proto = nf_ct_l4proto_find_get(l3num, l4num);
 108
 109         /* This protocol is not supportted, skip. */
 110         if (l4proto->l4proto != l4num) {
 111                 ret = -EOPNOTSUPP;
 112                 goto err_proto_put;
 113         }
 114
 115         if (matching) {
 116                 if (nlh->nlmsg_flags & NLM_F_REPLACE) {
 117                         /* You cannot replace one timeout policy by another of
 118                          * different kind, sorry.
 119                          */
 120                         if (matching->l3num != l3num ||
 121                             matching->l4proto->l4proto != l4num) {
 122                                 ret = -EINVAL;
 123                                 goto err_proto_put;
 124                         }
 125
 126                         ret = ctnl_timeout_parse_policy(matching, l4proto, net,
 127                                                         cda[CTA_TIMEOUT_DATA]);
 128                         return ret;
 129                 }
 130                 ret = -EBUSY;
 131                 goto err_proto_put;
 132         }
 133
 134         timeout = kzalloc(sizeof(struct ctnl_timeout) +
 135                           l4proto->ctnl_timeout.obj_size, GFP_KERNEL);
 136         if (timeout == NULL) {
 137                 ret = -ENOMEM;
 138                 goto err_proto_put;
 139         }
 140
 141         ret = ctnl_timeout_parse_policy(timeout, l4proto, net,
 142                                         cda[CTA_TIMEOUT_DATA]);
 143         if (ret < 0)
 144                 goto err;
 145
 146         strcpy(timeout->name, nla_data(cda[CTA_TIMEOUT_NAME]));
 147         timeout->l3num = l3num;
 148         timeout->l4proto = l4proto;
 149         atomic_set(&timeout->refcnt, 1);
 150         list_add_tail_rcu(&timeout->head, &cttimeout_list);
 151
 152         return 0;
 153 err:
 154         kfree(timeout);
 155 err_proto_put:
 156         nf_ct_l4proto_put(l4proto);
 157         return ret;
 158 }
 159
 160 static int
 161 ctnl_timeout_fill_info(struct sk_buff *skb, u32 portid, u32 seq, u32 type,
 162                        int event, struct ctnl_timeout *timeout)
 163 {
 164         struct nlmsghdr *nlh;
 165         struct nfgenmsg *nfmsg;
 166         unsigned int flags = portid ? NLM_F_MULTI : 0;
 167         struct nf_conntrack_l4proto *l4proto = timeout->l4proto;
 168
 169         event |= NFNL_SUBSYS_CTNETLINK_TIMEOUT << 8;
 170         nlh = nlmsg_put(skb, portid, seq, event, sizeof(*nfmsg), flags);
 171         if (nlh == NULL)
 172                 goto nlmsg_failure;
 173
 174         nfmsg = nlmsg_data(nlh);
 175         nfmsg->nfgen_family = AF_UNSPEC;
 176         nfmsg->version = NFNETLINK_V0;
 177         nfmsg->res_id = 0;
 178
 179         if (nla_put_string(skb, CTA_TIMEOUT_NAME, timeout->name) ||
 180             nla_put_be16(skb, CTA_TIMEOUT_L3PROTO, htons(timeout->l3num)) ||
 181             nla_put_u8(skb, CTA_TIMEOUT_L4PROTO, timeout->l4proto->l4proto) ||
 182             nla_put_be32(skb, CTA_TIMEOUT_USE,
 183                          htonl(atomic_read(&timeout->refcnt))))
 184                 goto nla_put_failure;
 185
 186         if (likely(l4proto->ctnl_timeout.obj_to_nlattr)) {
 187                 struct nlattr *nest_parms;
 188                 int ret;
 189
 190                 nest_parms = nla_nest_start(skb,
 191                                             CTA_TIMEOUT_DATA | NLA_F_NESTED);
 192                 if (!nest_parms)
 193                         goto nla_put_failure;
 194
 195                 ret = l4proto->ctnl_timeout.obj_to_nlattr(skb, &timeout->data);
 196                 if (ret < 0)
 197                         goto nla_put_failure;
 198
 199                 nla_nest_end(skb, nest_parms);
 200         }
 201
 202         nlmsg_end(skb, nlh);
 203         return skb->len;
 204
 205 nlmsg_failure:
 206 nla_put_failure:
 207         nlmsg_cancel(skb, nlh);
 208         return -1;
 209 }
 210
 211 static int
 212 ctnl_timeout_dump(struct sk_buff *skb, struct netlink_callback *cb)
 213 {
 214         struct ctnl_timeout *cur, *last;
 215
 216         if (cb->args[2])
 217                 return 0;
 218
 219         last = (struct ctnl_timeout *)cb->args[1];
 220         if (cb->args[1])
 221                 cb->args[1] = 0;
 222
 223         rcu_read_lock();
 224         list_for_each_entry_rcu(cur, &cttimeout_list, head) {
 225                 if (last) {
 226                         if (cur != last)
 227                                 continue;
 228
 229                         last = NULL;
 230                 }
 231                 if (ctnl_timeout_fill_info(skb, NETLINK_CB(cb->skb).portid,
 232                                            cb->nlh->nlmsg_seq,
 233                                            NFNL_MSG_TYPE(cb->nlh->nlmsg_type),
 234                                            IPCTNL_MSG_TIMEOUT_NEW, cur) < 0) {
 235                         cb->args[1] = (unsigned long)cur;
 236                         break;
 237                 }
 238         }
 239         if (!cb->args[1])
 240                 cb->args[2] = 1;
 241         rcu_read_unlock();
 242         return skb->len;
 243 }
 244
 245 static int
 246 cttimeout_get_timeout(struct sock *ctnl, struct sk_buff *skb,
 247                       const struct nlmsghdr *nlh,
 248                       const struct nlattr * const cda[])
 249 {
 250         int ret = -ENOENT;
 251         char *name;
 252         struct ctnl_timeout *cur;
 253
 254         if (nlh->nlmsg_flags & NLM_F_DUMP) {
 255                 struct netlink_dump_control c = {
 256                         .dump = ctnl_timeout_dump,
 257                 };
 258                 return netlink_dump_start(ctnl, skb, nlh, &c);
 259         }
 260
 261         if (!cda[CTA_TIMEOUT_NAME])
 262                 return -EINVAL;
 263         name = nla_data(cda[CTA_TIMEOUT_NAME]);
 264
 265         list_for_each_entry(cur, &cttimeout_list, head) {
 266                 struct sk_buff *skb2;
 267
 268                 if (strncmp(cur->name, name, CTNL_TIMEOUT_NAME_MAX) != 0)
 269                         continue;
 270
 271                 skb2 = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
 272                 if (skb2 == NULL) {
 273                         ret = -ENOMEM;
 274                         break;
 275                 }
 276
 277                 ret = ctnl_timeout_fill_info(skb2, NETLINK_CB(skb).portid,
 278                                              nlh->nlmsg_seq,
 279                                              NFNL_MSG_TYPE(nlh->nlmsg_type),
 280                                              IPCTNL_MSG_TIMEOUT_NEW, cur);
 281                 if (ret <= 0) {
 282                         kfree_skb(skb2);
 283                         break;
 284                 }
 285                 ret = netlink_unicast(ctnl, skb2, NETLINK_CB(skb).portid,
 286                                         MSG_DONTWAIT);
 287                 if (ret > 0)
 288                         ret = 0;
 289
 290                 /* this avoids a loop in nfnetlink. */
 291                 return ret == -EAGAIN ? -ENOBUFS : ret;
 292         }
 293         return ret;
 294 }
 295
 296 /* try to delete object, fail if it is still in use. */
 297 static int ctnl_timeout_try_del(struct ctnl_timeout *timeout)
 298 {
 299         int ret = 0;
 300
 301         /* we want to avoid races with nf_ct_timeout_find_get. */
 302         if (atomic_dec_and_test(&timeout->refcnt)) {
 303                 /* We are protected by nfnl mutex. */
 304                 list_del_rcu(&timeout->head);
 305                 nf_ct_l4proto_put(timeout->l4proto);
 306                 kfree_rcu(timeout, rcu_head);
 307         } else {
 308                 /* still in use, restore reference counter. */
 309                 atomic_inc(&timeout->refcnt);
 310                 ret = -EBUSY;
 311         }
 312         return ret;
 313 }
 314
 315 static int
 316 cttimeout_del_timeout(struct sock *ctnl, struct sk_buff *skb,
 317                       const struct nlmsghdr *nlh,
 318                       const struct nlattr * const cda[])
 319 {
 320         char *name;
 321         struct ctnl_timeout *cur;
 322         int ret = -ENOENT;
 323
 324         if (!cda[CTA_TIMEOUT_NAME]) {
 325                 list_for_each_entry(cur, &cttimeout_list, head)
 326                         ctnl_timeout_try_del(cur);
 327
 328                 return 0;
 329         }
 330         name = nla_data(cda[CTA_TIMEOUT_NAME]);
 331
 332         list_for_each_entry(cur, &cttimeout_list, head) {
 333                 if (strncmp(cur->name, name, CTNL_TIMEOUT_NAME_MAX) != 0)
 334                         continue;
 335
 336                 ret = ctnl_timeout_try_del(cur);
 337                 if (ret < 0)
 338                         return ret;
 339
 340                 break;
 341         }
 342         return ret;
 343 }
 344
 345 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT
 346 static struct ctnl_timeout *ctnl_timeout_find_get(const char *name)
 347 {
 348         struct ctnl_timeout *timeout, *matching = NULL;
 349
 350         rcu_read_lock();
 351         list_for_each_entry_rcu(timeout, &cttimeout_list, head) {
 352                 if (strncmp(timeout->name, name, CTNL_TIMEOUT_NAME_MAX) != 0)
 353                         continue;
 354
 355                 if (!try_module_get(THIS_MODULE))
 356                         goto err;
 357
 358                 if (!atomic_inc_not_zero(&timeout->refcnt)) {
 359                         module_put(THIS_MODULE);
 360                         goto err;
 361                 }
 362                 matching = timeout;
 363                 break;
 364         }
 365 err:
 366         rcu_read_unlock();
 367         return matching;
 368 }
 369
 370 static void ctnl_timeout_put(struct ctnl_timeout *timeout)
 371 {
 372         atomic_dec(&timeout->refcnt);
 373         module_put(THIS_MODULE);
 374 }
 375 #endif /* CONFIG_NF_CONNTRACK_TIMEOUT */
 376
 377 static const struct nfnl_callback cttimeout_cb[IPCTNL_MSG_TIMEOUT_MAX] = {
 378         [IPCTNL_MSG_TIMEOUT_NEW]        = { .call = cttimeout_new_timeout,
 379                                             .attr_count = CTA_TIMEOUT_MAX,
 380                                             .policy = cttimeout_nla_policy },
 381         [IPCTNL_MSG_TIMEOUT_GET]        = { .call = cttimeout_get_timeout,
 382                                             .attr_count = CTA_TIMEOUT_MAX,
 383                                             .policy = cttimeout_nla_policy },
 384         [IPCTNL_MSG_TIMEOUT_DELETE]     = { .call = cttimeout_del_timeout,
 385                                             .attr_count = CTA_TIMEOUT_MAX,
 386                                             .policy = cttimeout_nla_policy },
 387 };
 388
 389 static const struct nfnetlink_subsystem cttimeout_subsys = {
 390         .name                           = "conntrack_timeout",
 391         .subsys_id                      = NFNL_SUBSYS_CTNETLINK_TIMEOUT,
 392         .cb_count                       = IPCTNL_MSG_TIMEOUT_MAX,
 393         .cb                             = cttimeout_cb,
 394 };
 395
 396 MODULE_ALIAS_NFNL_SUBSYS(NFNL_SUBSYS_CTNETLINK_TIMEOUT);
 397
 398 static int __init cttimeout_init(void)
 399 {
 400         int ret;
 401
 402         ret = nfnetlink_subsys_register(&cttimeout_subsys);
 403         if (ret < 0) {
 404                 pr_err("cttimeout_init: cannot register cttimeout with "
 405                         "nfnetlink.\n");
 406                 goto err_out;
 407         }
 408 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT
 409         RCU_INIT_POINTER(nf_ct_timeout_find_get_hook, ctnl_timeout_find_get);
 410         RCU_INIT_POINTER(nf_ct_timeout_put_hook, ctnl_timeout_put);
 411 #endif /* CONFIG_NF_CONNTRACK_TIMEOUT */
 412         return 0;
 413
 414 err_out:
 415         return ret;
 416 }
 417
 418 static void __exit cttimeout_exit(void)
 419 {
 420         struct ctnl_timeout *cur, *tmp;
 421
 422         pr_info("cttimeout: unregistering from nfnetlink.\n");
 423
 424         nfnetlink_subsys_unregister(&cttimeout_subsys);
 425         list_for_each_entry_safe(cur, tmp, &cttimeout_list, head) {
 426                 list_del_rcu(&cur->head);
 427                 /* We are sure that our objects have no clients at this point,
 428                  * it's safe to release them all without checking refcnt.
 429                  */
 430                 nf_ct_l4proto_put(cur->l4proto);
 431                 kfree_rcu(cur, rcu_head);
 432         }
 433 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT
 434         RCU_INIT_POINTER(nf_ct_timeout_find_get_hook, NULL);
 435         RCU_INIT_POINTER(nf_ct_timeout_put_hook, NULL);
 436 #endif /* CONFIG_NF_CONNTRACK_TIMEOUT */
 437 }
 438
 439 module_init(cttimeout_init);
 440 module_exit(cttimeout_exit);