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