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                                const struct nlattr *attr)
  54 {
  55         int ret = 0;
  56
  57         if (likely(l4proto->ctnl_timeout.nlattr_to_obj)) {
  58                 struct nlattr *tb[l4proto->ctnl_timeout.nlattr_max+1];
  59
  60                 nla_parse_nested(tb, l4proto->ctnl_timeout.nlattr_max,
  61                                  attr, l4proto->ctnl_timeout.nla_policy);
  62
  63                 ret = l4proto->ctnl_timeout.nlattr_to_obj(tb, &timeout->data);
  64         }
  65         return ret;
  66 }
  67
  68 static int
  69 cttimeout_new_timeout(struct sock *ctnl, struct sk_buff *skb,
  70                       const struct nlmsghdr *nlh,
  71                       const struct nlattr * const cda[])
  72 {
  73         __u16 l3num;
  74         __u8 l4num;
  75         struct nf_conntrack_l4proto *l4proto;
  76         struct ctnl_timeout *timeout, *matching = NULL;
  77         char *name;
  78         int ret;
  79
  80         if (!cda[CTA_TIMEOUT_NAME] ||
  81             !cda[CTA_TIMEOUT_L3PROTO] ||
  82             !cda[CTA_TIMEOUT_L4PROTO] ||
  83             !cda[CTA_TIMEOUT_DATA])
  84                 return -EINVAL;
  85
  86         name = nla_data(cda[CTA_TIMEOUT_NAME]);
  87         l3num = ntohs(nla_get_be16(cda[CTA_TIMEOUT_L3PROTO]));
  88         l4num = nla_get_u8(cda[CTA_TIMEOUT_L4PROTO]);
  89
  90         list_for_each_entry(timeout, &cttimeout_list, head) {
  91                 if (strncmp(timeout->name, name, CTNL_TIMEOUT_NAME_MAX) != 0)
  92                         continue;
  93
  94                 if (nlh->nlmsg_flags & NLM_F_EXCL)
  95                         return -EEXIST;
  96
  97                 matching = timeout;
  98                 break;
  99         }
 100
 101         l4proto = __nf_ct_l4proto_find(l3num, l4num);
 102
 103         /* This protocol is not supportted, skip. */
 104         if (l4proto->l4proto != l4num)
 105                 return -EOPNOTSUPP;
 106
 107         if (matching) {
 108                 if (nlh->nlmsg_flags & NLM_F_REPLACE) {
 109                         /* You cannot replace one timeout policy by another of
 110                          * different kind, sorry.
 111                          */
 112                         if (matching->l3num != l3num ||
 113                             matching->l4num != l4num)
 114                                 return -EINVAL;
 115
 116                         ret = ctnl_timeout_parse_policy(matching, l4proto,
 117                                                         cda[CTA_TIMEOUT_DATA]);
 118                         return ret;
 119                 }
 120                 return -EBUSY;
 121         }
 122
 123         timeout = kzalloc(sizeof(struct ctnl_timeout) +
 124                           l4proto->ctnl_timeout.obj_size, GFP_KERNEL);
 125         if (timeout == NULL)
 126                 return -ENOMEM;
 127
 128         ret = ctnl_timeout_parse_policy(timeout, l4proto,
 129                                         cda[CTA_TIMEOUT_DATA]);
 130         if (ret < 0)
 131                 goto err;
 132
 133         strcpy(timeout->name, nla_data(cda[CTA_TIMEOUT_NAME]));
 134         timeout->l3num = l3num;
 135         timeout->l4num = l4num;
 136         atomic_set(&timeout->refcnt, 1);
 137         list_add_tail_rcu(&timeout->head, &cttimeout_list);
 138
 139         return 0;
 140 err:
 141         kfree(timeout);
 142         return ret;
 143 }
 144
 145 static int
 146 ctnl_timeout_fill_info(struct sk_buff *skb, u32 pid, u32 seq, u32 type,
 147                        int event, struct ctnl_timeout *timeout)
 148 {
 149         struct nlmsghdr *nlh;
 150         struct nfgenmsg *nfmsg;
 151         unsigned int flags = pid ? NLM_F_MULTI : 0;
 152         struct nf_conntrack_l4proto *l4proto;
 153
 154         event |= NFNL_SUBSYS_CTNETLINK_TIMEOUT << 8;
 155         nlh = nlmsg_put(skb, pid, seq, event, sizeof(*nfmsg), flags);
 156         if (nlh == NULL)
 157                 goto nlmsg_failure;
 158
 159         nfmsg = nlmsg_data(nlh);
 160         nfmsg->nfgen_family = AF_UNSPEC;
 161         nfmsg->version = NFNETLINK_V0;
 162         nfmsg->res_id = 0;
 163
 164         NLA_PUT_STRING(skb, CTA_TIMEOUT_NAME, timeout->name);
 165         NLA_PUT_BE16(skb, CTA_TIMEOUT_L3PROTO, htons(timeout->l3num));
 166         NLA_PUT_U8(skb, CTA_TIMEOUT_L4PROTO, timeout->l4num);
 167         NLA_PUT_BE32(skb, CTA_TIMEOUT_USE,
 168                         htonl(atomic_read(&timeout->refcnt)));
 169
 170         l4proto = __nf_ct_l4proto_find(timeout->l3num, timeout->l4num);
 171
 172         /* If the timeout object does not match the layer 4 protocol tracker,
 173          * then skip dumping the data part since we don't know how to
 174          * interpret it. This may happen for UPDlite, SCTP and DCCP since
 175          * you can unload the module.
 176          */
 177         if (timeout->l4num != l4proto->l4proto)
 178                 goto out;
 179
 180         if (likely(l4proto->ctnl_timeout.obj_to_nlattr)) {
 181                 struct nlattr *nest_parms;
 182                 int ret;
 183
 184                 nest_parms = nla_nest_start(skb,
 185                                             CTA_TIMEOUT_DATA | NLA_F_NESTED);
 186                 if (!nest_parms)
 187                         goto nla_put_failure;
 188
 189                 ret = l4proto->ctnl_timeout.obj_to_nlattr(skb, &timeout->data);
 190                 if (ret < 0)
 191                         goto nla_put_failure;
 192
 193                 nla_nest_end(skb, nest_parms);
 194         }
 195 out:
 196         nlmsg_end(skb, nlh);
 197         return skb->len;
 198
 199 nlmsg_failure:
 200 nla_put_failure:
 201         nlmsg_cancel(skb, nlh);
 202         return -1;
 203 }
 204
 205 static int
 206 ctnl_timeout_dump(struct sk_buff *skb, struct netlink_callback *cb)
 207 {
 208         struct ctnl_timeout *cur, *last;
 209
 210         if (cb->args[2])
 211                 return 0;
 212
 213         last = (struct ctnl_timeout *)cb->args[1];
 214         if (cb->args[1])
 215                 cb->args[1] = 0;
 216
 217         rcu_read_lock();
 218         list_for_each_entry_rcu(cur, &cttimeout_list, head) {
 219                 if (last && cur != last)
 220                         continue;
 221
 222                 if (ctnl_timeout_fill_info(skb, NETLINK_CB(cb->skb).pid,
 223                                            cb->nlh->nlmsg_seq,
 224                                            NFNL_MSG_TYPE(cb->nlh->nlmsg_type),
 225                                            IPCTNL_MSG_TIMEOUT_NEW, cur) < 0) {
 226                         cb->args[1] = (unsigned long)cur;
 227                         break;
 228                 }
 229         }
 230         if (!cb->args[1])
 231                 cb->args[2] = 1;
 232         rcu_read_unlock();
 233         return skb->len;
 234 }
 235
 236 static int
 237 cttimeout_get_timeout(struct sock *ctnl, struct sk_buff *skb,
 238                       const struct nlmsghdr *nlh,
 239                       const struct nlattr * const cda[])
 240 {
 241         int ret = -ENOENT;
 242         char *name;
 243         struct ctnl_timeout *cur;
 244
 245         if (nlh->nlmsg_flags & NLM_F_DUMP) {
 246                 struct netlink_dump_control c = {
 247                         .dump = ctnl_timeout_dump,
 248                 };
 249                 return netlink_dump_start(ctnl, skb, nlh, &c);
 250         }
 251
 252         if (!cda[CTA_TIMEOUT_NAME])
 253                 return -EINVAL;
 254         name = nla_data(cda[CTA_TIMEOUT_NAME]);
 255
 256         list_for_each_entry(cur, &cttimeout_list, head) {
 257                 struct sk_buff *skb2;
 258
 259                 if (strncmp(cur->name, name, CTNL_TIMEOUT_NAME_MAX) != 0)
 260                         continue;
 261
 262                 skb2 = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
 263                 if (skb2 == NULL) {
 264                         ret = -ENOMEM;
 265                         break;
 266                 }
 267
 268                 ret = ctnl_timeout_fill_info(skb2, NETLINK_CB(skb).pid,
 269                                              nlh->nlmsg_seq,
 270                                              NFNL_MSG_TYPE(nlh->nlmsg_type),
 271                                              IPCTNL_MSG_TIMEOUT_NEW, cur);
 272                 if (ret <= 0) {
 273                         kfree_skb(skb2);
 274                         break;
 275                 }
 276                 ret = netlink_unicast(ctnl, skb2, NETLINK_CB(skb).pid,
 277                                         MSG_DONTWAIT);
 278                 if (ret > 0)
 279                         ret = 0;
 280
 281                 /* this avoids a loop in nfnetlink. */
 282                 return ret == -EAGAIN ? -ENOBUFS : ret;
 283         }
 284         return ret;
 285 }
 286
 287 /* try to delete object, fail if it is still in use. */
 288 static int ctnl_timeout_try_del(struct ctnl_timeout *timeout)
 289 {
 290         int ret = 0;
 291
 292         /* we want to avoid races with nf_ct_timeout_find_get. */
 293         if (atomic_dec_and_test(&timeout->refcnt)) {
 294                 /* We are protected by nfnl mutex. */
 295                 list_del_rcu(&timeout->head);
 296                 kfree_rcu(timeout, rcu_head);
 297         } else {
 298                 /* still in use, restore reference counter. */
 299                 atomic_inc(&timeout->refcnt);
 300                 ret = -EBUSY;
 301         }
 302         return ret;
 303 }
 304
 305 static int
 306 cttimeout_del_timeout(struct sock *ctnl, struct sk_buff *skb,
 307                       const struct nlmsghdr *nlh,
 308                       const struct nlattr * const cda[])
 309 {
 310         char *name;
 311         struct ctnl_timeout *cur;
 312         int ret = -ENOENT;
 313
 314         if (!cda[CTA_TIMEOUT_NAME]) {
 315                 list_for_each_entry(cur, &cttimeout_list, head)
 316                         ctnl_timeout_try_del(cur);
 317
 318                 return 0;
 319         }
 320         name = nla_data(cda[CTA_TIMEOUT_NAME]);
 321
 322         list_for_each_entry(cur, &cttimeout_list, head) {
 323                 if (strncmp(cur->name, name, CTNL_TIMEOUT_NAME_MAX) != 0)
 324                         continue;
 325
 326                 ret = ctnl_timeout_try_del(cur);
 327                 if (ret < 0)
 328                         return ret;
 329
 330                 break;
 331         }
 332         return ret;
 333 }
 334
 335 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT
 336 static struct ctnl_timeout *ctnl_timeout_find_get(const char *name)
 337 {
 338         struct ctnl_timeout *timeout, *matching = NULL;
 339
 340         rcu_read_lock();
 341         list_for_each_entry_rcu(timeout, &cttimeout_list, head) {
 342                 if (strncmp(timeout->name, name, CTNL_TIMEOUT_NAME_MAX) != 0)
 343                         continue;
 344
 345                 if (!try_module_get(THIS_MODULE))
 346                         goto err;
 347
 348                 if (!atomic_inc_not_zero(&timeout->refcnt)) {
 349                         module_put(THIS_MODULE);
 350                         goto err;
 351                 }
 352                 matching = timeout;
 353                 break;
 354         }
 355 err:
 356         rcu_read_unlock();
 357         return matching;
 358 }
 359
 360 static void ctnl_timeout_put(struct ctnl_timeout *timeout)
 361 {
 362         atomic_dec(&timeout->refcnt);
 363         module_put(THIS_MODULE);
 364 }
 365 #endif /* CONFIG_NF_CONNTRACK_TIMEOUT */
 366
 367 static const struct nfnl_callback cttimeout_cb[IPCTNL_MSG_TIMEOUT_MAX] = {
 368         [IPCTNL_MSG_TIMEOUT_NEW]        = { .call = cttimeout_new_timeout,
 369                                             .attr_count = CTA_TIMEOUT_MAX,
 370                                             .policy = cttimeout_nla_policy },
 371         [IPCTNL_MSG_TIMEOUT_GET]        = { .call = cttimeout_get_timeout,
 372                                             .attr_count = CTA_TIMEOUT_MAX,
 373                                             .policy = cttimeout_nla_policy },
 374         [IPCTNL_MSG_TIMEOUT_DELETE]     = { .call = cttimeout_del_timeout,
 375                                             .attr_count = CTA_TIMEOUT_MAX,
 376                                             .policy = cttimeout_nla_policy },
 377 };
 378
 379 static const struct nfnetlink_subsystem cttimeout_subsys = {
 380         .name                           = "conntrack_timeout",
 381         .subsys_id                      = NFNL_SUBSYS_CTNETLINK_TIMEOUT,
 382         .cb_count                       = IPCTNL_MSG_TIMEOUT_MAX,
 383         .cb                             = cttimeout_cb,
 384 };
 385
 386 MODULE_ALIAS_NFNL_SUBSYS(NFNL_SUBSYS_CTNETLINK_TIMEOUT);
 387
 388 static int __init cttimeout_init(void)
 389 {
 390         int ret;
 391
 392         ret = nfnetlink_subsys_register(&cttimeout_subsys);
 393         if (ret < 0) {
 394                 pr_err("cttimeout_init: cannot register cttimeout with "
 395                         "nfnetlink.\n");
 396                 goto err_out;
 397         }
 398 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT
 399         RCU_INIT_POINTER(nf_ct_timeout_find_get_hook, ctnl_timeout_find_get);
 400         RCU_INIT_POINTER(nf_ct_timeout_put_hook, ctnl_timeout_put);
 401 #endif /* CONFIG_NF_CONNTRACK_TIMEOUT */
 402         return 0;
 403
 404 err_out:
 405         return ret;
 406 }
 407
 408 static void __exit cttimeout_exit(void)
 409 {
 410         struct ctnl_timeout *cur, *tmp;
 411
 412         pr_info("cttimeout: unregistering from nfnetlink.\n");
 413
 414         nfnetlink_subsys_unregister(&cttimeout_subsys);
 415         list_for_each_entry_safe(cur, tmp, &cttimeout_list, head) {
 416                 list_del_rcu(&cur->head);
 417                 /* We are sure that our objects have no clients at this point,
 418                  * it's safe to release them all without checking refcnt.
 419                  */
 420                 kfree_rcu(cur, rcu_head);
 421         }
 422 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT
 423         RCU_INIT_POINTER(nf_ct_timeout_find_get_hook, NULL);
 424         RCU_INIT_POINTER(nf_ct_timeout_put_hook, NULL);
 425 #endif /* CONFIG_NF_CONNTRACK_TIMEOUT */
 426 }
 427
 428 module_init(cttimeout_init);
 429 module_exit(cttimeout_exit);