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
  33 #include <linux/netfilter/nfnetlink.h>
  34 #include <linux/netfilter/nfnetlink_cttimeout.h>
  35
  36 MODULE_LICENSE("GPL");
  37 MODULE_AUTHOR("Pablo Neira Ayuso <pablo@netfilter.org>");
  38 MODULE_DESCRIPTION("cttimeout: Extended Netfilter Connection Tracking timeout tuning");
  39
  40 static LIST_HEAD(cttimeout_list);
  41
  42 static const struct nla_policy cttimeout_nla_policy[CTA_TIMEOUT_MAX+1] = {
  43         [CTA_TIMEOUT_NAME]      = { .type = NLA_NUL_STRING },
  44         [CTA_TIMEOUT_L3PROTO]   = { .type = NLA_U16 },
  45         [CTA_TIMEOUT_L4PROTO]   = { .type = NLA_U8 },
  46         [CTA_TIMEOUT_DATA]      = { .type = NLA_NESTED },
  47 };
  48
  49 static int
  50 ctnl_timeout_parse_policy(struct ctnl_timeout *timeout,
  51                                struct nf_conntrack_l4proto *l4proto,
  52                                const struct nlattr *attr)
  53 {
  54         int ret = 0;
  55
  56         if (likely(l4proto->ctnl_timeout.nlattr_to_obj)) {
  57                 struct nlattr *tb[l4proto->ctnl_timeout.nlattr_max+1];
  58
  59                 nla_parse_nested(tb, l4proto->ctnl_timeout.nlattr_max,
  60                                  attr, l4proto->ctnl_timeout.nla_policy);
  61
  62                 ret = l4proto->ctnl_timeout.nlattr_to_obj(tb, &timeout->data);
  63         }
  64         return ret;
  65 }
  66
  67 static int
  68 cttimeout_new_timeout(struct sock *ctnl, struct sk_buff *skb,
  69                       const struct nlmsghdr *nlh,
  70                       const struct nlattr * const cda[])
  71 {
  72         __u16 l3num;
  73         __u8 l4num;
  74         struct nf_conntrack_l4proto *l4proto;
  75         struct ctnl_timeout *timeout, *matching = NULL;
  76         char *name;
  77         int ret;
  78
  79         if (!cda[CTA_TIMEOUT_NAME] ||
  80             !cda[CTA_TIMEOUT_L3PROTO] ||
  81             !cda[CTA_TIMEOUT_L4PROTO] ||
  82             !cda[CTA_TIMEOUT_DATA])
  83                 return -EINVAL;
  84
  85         name = nla_data(cda[CTA_TIMEOUT_NAME]);
  86         l3num = ntohs(nla_get_be16(cda[CTA_TIMEOUT_L3PROTO]));
  87         l4num = nla_get_u8(cda[CTA_TIMEOUT_L4PROTO]);
  88
  89         list_for_each_entry(timeout, &cttimeout_list, head) {
  90                 if (strncmp(timeout->name, name, CTNL_TIMEOUT_NAME_MAX) != 0)
  91                         continue;
  92
  93                 if (nlh->nlmsg_flags & NLM_F_EXCL)
  94                         return -EEXIST;
  95
  96                 matching = timeout;
  97                 break;
  98         }
  99
 100         l4proto = __nf_ct_l4proto_find(l3num, l4num);
 101
 102         /* This protocol is not supportted, skip. */
 103         if (l4proto->l4proto != l4num)
 104                 return -EOPNOTSUPP;
 105
 106         if (matching) {
 107                 if (nlh->nlmsg_flags & NLM_F_REPLACE) {
 108                         /* You cannot replace one timeout policy by another of
 109                          * different kind, sorry.
 110                          */
 111                         if (matching->l3num != l3num ||
 112                             matching->l4num != l4num)
 113                                 return -EINVAL;
 114
 115                         ret = ctnl_timeout_parse_policy(matching, l4proto,
 116                                                         cda[CTA_TIMEOUT_DATA]);
 117                         return ret;
 118                 }
 119                 return -EBUSY;
 120         }
 121
 122         timeout = kzalloc(sizeof(struct ctnl_timeout) +
 123                           l4proto->ctnl_timeout.obj_size, GFP_KERNEL);
 124         if (timeout == NULL)
 125                 return -ENOMEM;
 126
 127         ret = ctnl_timeout_parse_policy(timeout, l4proto,
 128                                         cda[CTA_TIMEOUT_DATA]);
 129         if (ret < 0)
 130                 goto err;
 131
 132         strcpy(timeout->name, nla_data(cda[CTA_TIMEOUT_NAME]));
 133         timeout->l3num = l3num;
 134         timeout->l4num = l4num;
 135         atomic_set(&timeout->refcnt, 1);
 136         list_add_tail_rcu(&timeout->head, &cttimeout_list);
 137
 138         return 0;
 139 err:
 140         kfree(timeout);
 141         return ret;
 142 }
 143
 144 static int
 145 ctnl_timeout_fill_info(struct sk_buff *skb, u32 pid, u32 seq, u32 type,
 146                        int event, struct ctnl_timeout *timeout)
 147 {
 148         struct nlmsghdr *nlh;
 149         struct nfgenmsg *nfmsg;
 150         unsigned int flags = pid ? NLM_F_MULTI : 0;
 151         struct nf_conntrack_l4proto *l4proto;
 152
 153         event |= NFNL_SUBSYS_CTNETLINK_TIMEOUT << 8;
 154         nlh = nlmsg_put(skb, pid, seq, event, sizeof(*nfmsg), flags);
 155         if (nlh == NULL)
 156                 goto nlmsg_failure;
 157
 158         nfmsg = nlmsg_data(nlh);
 159         nfmsg->nfgen_family = AF_UNSPEC;
 160         nfmsg->version = NFNETLINK_V0;
 161         nfmsg->res_id = 0;
 162
 163         NLA_PUT_STRING(skb, CTA_TIMEOUT_NAME, timeout->name);
 164         NLA_PUT_BE16(skb, CTA_TIMEOUT_L3PROTO, htons(timeout->l3num));
 165         NLA_PUT_U8(skb, CTA_TIMEOUT_L4PROTO, timeout->l4num);
 166         NLA_PUT_BE32(skb, CTA_TIMEOUT_USE,
 167                         htonl(atomic_read(&timeout->refcnt)));
 168
 169         l4proto = __nf_ct_l4proto_find(timeout->l3num, timeout->l4num);
 170
 171         /* If the timeout object does not match the layer 4 protocol tracker,
 172          * then skip dumping the data part since we don't know how to
 173          * interpret it. This may happen for UPDlite, SCTP and DCCP since
 174          * you can unload the module.
 175          */
 176         if (timeout->l4num != l4proto->l4proto)
 177                 goto out;
 178
 179         if (likely(l4proto->ctnl_timeout.obj_to_nlattr)) {
 180                 struct nlattr *nest_parms;
 181                 int ret;
 182
 183                 nest_parms = nla_nest_start(skb,
 184                                             CTA_TIMEOUT_DATA | NLA_F_NESTED);
 185                 if (!nest_parms)
 186                         goto nla_put_failure;
 187
 188                 ret = l4proto->ctnl_timeout.obj_to_nlattr(skb, &timeout->data);
 189                 if (ret < 0)
 190                         goto nla_put_failure;
 191
 192                 nla_nest_end(skb, nest_parms);
 193         }
 194 out:
 195         nlmsg_end(skb, nlh);
 196         return skb->len;
 197
 198 nlmsg_failure:
 199 nla_put_failure:
 200         nlmsg_cancel(skb, nlh);
 201         return -1;
 202 }
 203
 204 static int
 205 ctnl_timeout_dump(struct sk_buff *skb, struct netlink_callback *cb)
 206 {
 207         struct ctnl_timeout *cur, *last;
 208
 209         if (cb->args[2])
 210                 return 0;
 211
 212         last = (struct ctnl_timeout *)cb->args[1];
 213         if (cb->args[1])
 214                 cb->args[1] = 0;
 215
 216         rcu_read_lock();
 217         list_for_each_entry_rcu(cur, &cttimeout_list, head) {
 218                 if (last && cur != last)
 219                         continue;
 220
 221                 if (ctnl_timeout_fill_info(skb, NETLINK_CB(cb->skb).pid,
 222                                            cb->nlh->nlmsg_seq,
 223                                            NFNL_MSG_TYPE(cb->nlh->nlmsg_type),
 224                                            IPCTNL_MSG_TIMEOUT_NEW, cur) < 0) {
 225                         cb->args[1] = (unsigned long)cur;
 226                         break;
 227                 }
 228         }
 229         if (!cb->args[1])
 230                 cb->args[2] = 1;
 231         rcu_read_unlock();
 232         return skb->len;
 233 }
 234
 235 static int
 236 cttimeout_get_timeout(struct sock *ctnl, struct sk_buff *skb,
 237                       const struct nlmsghdr *nlh,
 238                       const struct nlattr * const cda[])
 239 {
 240         int ret = -ENOENT;
 241         char *name;
 242         struct ctnl_timeout *cur;
 243
 244         if (nlh->nlmsg_flags & NLM_F_DUMP) {
 245                 struct netlink_dump_control c = {
 246                         .dump = ctnl_timeout_dump,
 247                 };
 248                 return netlink_dump_start(ctnl, skb, nlh, &c);
 249         }
 250
 251         if (!cda[CTA_TIMEOUT_NAME])
 252                 return -EINVAL;
 253         name = nla_data(cda[CTA_TIMEOUT_NAME]);
 254
 255         list_for_each_entry(cur, &cttimeout_list, head) {
 256                 struct sk_buff *skb2;
 257
 258                 if (strncmp(cur->name, name, CTNL_TIMEOUT_NAME_MAX) != 0)
 259                         continue;
 260
 261                 skb2 = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
 262                 if (skb2 == NULL) {
 263                         ret = -ENOMEM;
 264                         break;
 265                 }
 266
 267                 ret = ctnl_timeout_fill_info(skb2, NETLINK_CB(skb).pid,
 268                                              nlh->nlmsg_seq,
 269                                              NFNL_MSG_TYPE(nlh->nlmsg_type),
 270                                              IPCTNL_MSG_TIMEOUT_NEW, cur);
 271                 if (ret <= 0) {
 272                         kfree_skb(skb2);
 273                         break;
 274                 }
 275                 ret = netlink_unicast(ctnl, skb2, NETLINK_CB(skb).pid,
 276                                         MSG_DONTWAIT);
 277                 if (ret > 0)
 278                         ret = 0;
 279
 280                 /* this avoids a loop in nfnetlink. */
 281                 return ret == -EAGAIN ? -ENOBUFS : ret;
 282         }
 283         return ret;
 284 }
 285
 286 /* try to delete object, fail if it is still in use. */
 287 static int ctnl_timeout_try_del(struct ctnl_timeout *timeout)
 288 {
 289         int ret = 0;
 290
 291         /* we want to avoid races with nf_ct_timeout_find_get. */
 292         if (atomic_dec_and_test(&timeout->refcnt)) {
 293                 /* We are protected by nfnl mutex. */
 294                 list_del_rcu(&timeout->head);
 295                 kfree_rcu(timeout, rcu_head);
 296         } else {
 297                 /* still in use, restore reference counter. */
 298                 atomic_inc(&timeout->refcnt);
 299                 ret = -EBUSY;
 300         }
 301         return ret;
 302 }
 303
 304 static int
 305 cttimeout_del_timeout(struct sock *ctnl, struct sk_buff *skb,
 306                       const struct nlmsghdr *nlh,
 307                       const struct nlattr * const cda[])
 308 {
 309         char *name;
 310         struct ctnl_timeout *cur;
 311         int ret = -ENOENT;
 312
 313         if (!cda[CTA_TIMEOUT_NAME]) {
 314                 list_for_each_entry(cur, &cttimeout_list, head)
 315                         ctnl_timeout_try_del(cur);
 316
 317                 return 0;
 318         }
 319         name = nla_data(cda[CTA_TIMEOUT_NAME]);
 320
 321         list_for_each_entry(cur, &cttimeout_list, head) {
 322                 if (strncmp(cur->name, name, CTNL_TIMEOUT_NAME_MAX) != 0)
 323                         continue;
 324
 325                 ret = ctnl_timeout_try_del(cur);
 326                 if (ret < 0)
 327                         return ret;
 328
 329                 break;
 330         }
 331         return ret;
 332 }
 333
 334 static const struct nfnl_callback cttimeout_cb[IPCTNL_MSG_TIMEOUT_MAX] = {
 335         [IPCTNL_MSG_TIMEOUT_NEW]        = { .call = cttimeout_new_timeout,
 336                                             .attr_count = CTA_TIMEOUT_MAX,
 337                                             .policy = cttimeout_nla_policy },
 338         [IPCTNL_MSG_TIMEOUT_GET]        = { .call = cttimeout_get_timeout,
 339                                             .attr_count = CTA_TIMEOUT_MAX,
 340                                             .policy = cttimeout_nla_policy },
 341         [IPCTNL_MSG_TIMEOUT_DELETE]     = { .call = cttimeout_del_timeout,
 342                                             .attr_count = CTA_TIMEOUT_MAX,
 343                                             .policy = cttimeout_nla_policy },
 344 };
 345
 346 static const struct nfnetlink_subsystem cttimeout_subsys = {
 347         .name                           = "conntrack_timeout",
 348         .subsys_id                      = NFNL_SUBSYS_CTNETLINK_TIMEOUT,
 349         .cb_count                       = IPCTNL_MSG_TIMEOUT_MAX,
 350         .cb                             = cttimeout_cb,
 351 };
 352
 353 MODULE_ALIAS_NFNL_SUBSYS(NFNL_SUBSYS_CTNETLINK_TIMEOUT);
 354
 355 static int __init cttimeout_init(void)
 356 {
 357         int ret;
 358
 359         ret = nfnetlink_subsys_register(&cttimeout_subsys);
 360         if (ret < 0) {
 361                 pr_err("cttimeout_init: cannot register cttimeout with "
 362                         "nfnetlink.\n");
 363                 goto err_out;
 364         }
 365         return 0;
 366
 367 err_out:
 368         return ret;
 369 }
 370
 371 static void __exit cttimeout_exit(void)
 372 {
 373         struct ctnl_timeout *cur, *tmp;
 374
 375         pr_info("cttimeout: unregistering from nfnetlink.\n");
 376
 377         nfnetlink_subsys_unregister(&cttimeout_subsys);
 378         list_for_each_entry_safe(cur, tmp, &cttimeout_list, head) {
 379                 list_del_rcu(&cur->head);
 380                 /* We are sure that our objects have no clients at this point,
 381                  * it's safe to release them all without checking refcnt.
 382                  */
 383                 kfree_rcu(cur, rcu_head);
 384         }
 385 }
 386
 387 module_init(cttimeout_init);
 388 module_exit(cttimeout_exit);