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                 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) {
 224                         if (cur != last)
 225                                 continue;
 226
 227                         last = NULL;
 228                 }
 229                 if (ctnl_timeout_fill_info(skb, NETLINK_CB(cb->skb).portid,
 230                                            cb->nlh->nlmsg_seq,
 231                                            NFNL_MSG_TYPE(cb->nlh->nlmsg_type),
 232                                            IPCTNL_MSG_TIMEOUT_NEW, cur) < 0) {
 233                         cb->args[1] = (unsigned long)cur;
 234                         break;
 235                 }
 236         }
 237         if (!cb->args[1])
 238                 cb->args[2] = 1;
 239         rcu_read_unlock();
 240         return skb->len;
 241 }
 242
 243 static int
 244 cttimeout_get_timeout(struct sock *ctnl, struct sk_buff *skb,
 245                       const struct nlmsghdr *nlh,
 246                       const struct nlattr * const cda[])
 247 {
 248         int ret = -ENOENT;
 249         char *name;
 250         struct ctnl_timeout *cur;
 251
 252         if (nlh->nlmsg_flags & NLM_F_DUMP) {
 253                 struct netlink_dump_control c = {
 254                         .dump = ctnl_timeout_dump,
 255                 };
 256                 return netlink_dump_start(ctnl, skb, nlh, &c);
 257         }
 258
 259         if (!cda[CTA_TIMEOUT_NAME])
 260                 return -EINVAL;
 261         name = nla_data(cda[CTA_TIMEOUT_NAME]);
 262
 263         list_for_each_entry(cur, &cttimeout_list, head) {
 264                 struct sk_buff *skb2;
 265
 266                 if (strncmp(cur->name, name, CTNL_TIMEOUT_NAME_MAX) != 0)
 267                         continue;
 268
 269                 skb2 = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
 270                 if (skb2 == NULL) {
 271                         ret = -ENOMEM;
 272                         break;
 273                 }
 274
 275                 ret = ctnl_timeout_fill_info(skb2, NETLINK_CB(skb).portid,
 276                                              nlh->nlmsg_seq,
 277                                              NFNL_MSG_TYPE(nlh->nlmsg_type),
 278                                              IPCTNL_MSG_TIMEOUT_NEW, cur);
 279                 if (ret <= 0) {
 280                         kfree_skb(skb2);
 281                         break;
 282                 }
 283                 ret = netlink_unicast(ctnl, skb2, NETLINK_CB(skb).portid,
 284                                         MSG_DONTWAIT);
 285                 if (ret > 0)
 286                         ret = 0;
 287
 288                 /* this avoids a loop in nfnetlink. */
 289                 return ret == -EAGAIN ? -ENOBUFS : ret;
 290         }
 291         return ret;
 292 }
 293
 294 /* try to delete object, fail if it is still in use. */
 295 static int ctnl_timeout_try_del(struct ctnl_timeout *timeout)
 296 {
 297         int ret = 0;
 298
 299         /* we want to avoid races with nf_ct_timeout_find_get. */
 300         if (atomic_dec_and_test(&timeout->refcnt)) {
 301                 /* We are protected by nfnl mutex. */
 302                 list_del_rcu(&timeout->head);
 303                 nf_ct_l4proto_put(timeout->l4proto);
 304                 kfree_rcu(timeout, rcu_head);
 305         } else {
 306                 /* still in use, restore reference counter. */
 307                 atomic_inc(&timeout->refcnt);
 308                 ret = -EBUSY;
 309         }
 310         return ret;
 311 }
 312
 313 static int
 314 cttimeout_del_timeout(struct sock *ctnl, struct sk_buff *skb,
 315                       const struct nlmsghdr *nlh,
 316                       const struct nlattr * const cda[])
 317 {
 318         char *name;
 319         struct ctnl_timeout *cur;
 320         int ret = -ENOENT;
 321
 322         if (!cda[CTA_TIMEOUT_NAME]) {
 323                 list_for_each_entry(cur, &cttimeout_list, head)
 324                         ctnl_timeout_try_del(cur);
 325
 326                 return 0;
 327         }
 328         name = nla_data(cda[CTA_TIMEOUT_NAME]);
 329
 330         list_for_each_entry(cur, &cttimeout_list, head) {
 331                 if (strncmp(cur->name, name, CTNL_TIMEOUT_NAME_MAX) != 0)
 332                         continue;
 333
 334                 ret = ctnl_timeout_try_del(cur);
 335                 if (ret < 0)
 336                         return ret;
 337
 338                 break;
 339         }
 340         return ret;
 341 }
 342
 343 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT
 344 static struct ctnl_timeout *ctnl_timeout_find_get(const char *name)
 345 {
 346         struct ctnl_timeout *timeout, *matching = NULL;
 347
 348         rcu_read_lock();
 349         list_for_each_entry_rcu(timeout, &cttimeout_list, head) {
 350                 if (strncmp(timeout->name, name, CTNL_TIMEOUT_NAME_MAX) != 0)
 351                         continue;
 352
 353                 if (!try_module_get(THIS_MODULE))
 354                         goto err;
 355
 356                 if (!atomic_inc_not_zero(&timeout->refcnt)) {
 357                         module_put(THIS_MODULE);
 358                         goto err;
 359                 }
 360                 matching = timeout;
 361                 break;
 362         }
 363 err:
 364         rcu_read_unlock();
 365         return matching;
 366 }
 367
 368 static void ctnl_timeout_put(struct ctnl_timeout *timeout)
 369 {
 370         atomic_dec(&timeout->refcnt);
 371         module_put(THIS_MODULE);
 372 }
 373 #endif /* CONFIG_NF_CONNTRACK_TIMEOUT */
 374
 375 static const struct nfnl_callback cttimeout_cb[IPCTNL_MSG_TIMEOUT_MAX] = {
 376         [IPCTNL_MSG_TIMEOUT_NEW]        = { .call = cttimeout_new_timeout,
 377                                             .attr_count = CTA_TIMEOUT_MAX,
 378                                             .policy = cttimeout_nla_policy },
 379         [IPCTNL_MSG_TIMEOUT_GET]        = { .call = cttimeout_get_timeout,
 380                                             .attr_count = CTA_TIMEOUT_MAX,
 381                                             .policy = cttimeout_nla_policy },
 382         [IPCTNL_MSG_TIMEOUT_DELETE]     = { .call = cttimeout_del_timeout,
 383                                             .attr_count = CTA_TIMEOUT_MAX,
 384                                             .policy = cttimeout_nla_policy },
 385 };
 386
 387 static const struct nfnetlink_subsystem cttimeout_subsys = {
 388         .name                           = "conntrack_timeout",
 389         .subsys_id                      = NFNL_SUBSYS_CTNETLINK_TIMEOUT,
 390         .cb_count                       = IPCTNL_MSG_TIMEOUT_MAX,
 391         .cb                             = cttimeout_cb,
 392 };
 393
 394 MODULE_ALIAS_NFNL_SUBSYS(NFNL_SUBSYS_CTNETLINK_TIMEOUT);
 395
 396 static int __init cttimeout_init(void)
 397 {
 398         int ret;
 399
 400         ret = nfnetlink_subsys_register(&cttimeout_subsys);
 401         if (ret < 0) {
 402                 pr_err("cttimeout_init: cannot register cttimeout with "
 403                         "nfnetlink.\n");
 404                 goto err_out;
 405         }
 406 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT
 407         RCU_INIT_POINTER(nf_ct_timeout_find_get_hook, ctnl_timeout_find_get);
 408         RCU_INIT_POINTER(nf_ct_timeout_put_hook, ctnl_timeout_put);
 409 #endif /* CONFIG_NF_CONNTRACK_TIMEOUT */
 410         return 0;
 411
 412 err_out:
 413         return ret;
 414 }
 415
 416 static void __exit cttimeout_exit(void)
 417 {
 418         struct ctnl_timeout *cur, *tmp;
 419
 420         pr_info("cttimeout: unregistering from nfnetlink.\n");
 421
 422         nfnetlink_subsys_unregister(&cttimeout_subsys);
 423         list_for_each_entry_safe(cur, tmp, &cttimeout_list, head) {
 424                 list_del_rcu(&cur->head);
 425                 /* We are sure that our objects have no clients at this point,
 426                  * it's safe to release them all without checking refcnt.
 427                  */
 428                 nf_ct_l4proto_put(cur->l4proto);
 429                 kfree_rcu(cur, rcu_head);
 430         }
 431 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT
 432         RCU_INIT_POINTER(nf_ct_timeout_find_get_hook, NULL);
 433         RCU_INIT_POINTER(nf_ct_timeout_put_hook, NULL);
 434         synchronize_rcu();
 435 #endif /* CONFIG_NF_CONNTRACK_TIMEOUT */
 436 }
 437
 438 module_init(cttimeout_init);
 439 module_exit(cttimeout_exit);