net/netfilter/nfnetlink_acct.c

   1 /*
   2  * (C) 2011 Pablo Neira Ayuso <[email protected]>
   3  * (C) 2011 Intra2net AG <http://www.intra2net.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/skbuff.h>
  13 #include <linux/atomic.h>
  14 #include <linux/netlink.h>
  15 #include <linux/rculist.h>
  16 #include <linux/slab.h>
  17 #include <linux/types.h>
  18 #include <linux/errno.h>
  19 #include <net/netlink.h>
  20 #include <net/sock.h>
  21
  22 #include <linux/netfilter.h>
  23 #include <linux/netfilter/nfnetlink.h>
  24 #include <linux/netfilter/nfnetlink_acct.h>
  25
  26 MODULE_LICENSE("GPL");
  27 MODULE_AUTHOR("Pablo Neira Ayuso <[email protected]>");
  28 MODULE_DESCRIPTION("nfacct: Extended Netfilter accounting infrastructure");
  29
  30 static LIST_HEAD(nfnl_acct_list);
  31
  32 struct nf_acct {
  33         atomic64_t              pkts;
  34         atomic64_t              bytes;
  35         unsigned long           flags;
  36         struct list_head        head;
  37         atomic_t                refcnt;
  38         char                    name[NFACCT_NAME_MAX];
  39         struct rcu_head         rcu_head;
  40         char                    data[0];
  41 };
  42
  43 struct nfacct_filter {
  44         u32 value;
  45         u32 mask;
  46 };
  47
  48 #define NFACCT_F_QUOTA (NFACCT_F_QUOTA_PKTS | NFACCT_F_QUOTA_BYTES)
  49 #define NFACCT_OVERQUOTA_BIT    2       /* NFACCT_F_OVERQUOTA */
  50
  51 static int
  52 nfnl_acct_new(struct sock *nfnl, struct sk_buff *skb,
  53              const struct nlmsghdr *nlh, const struct nlattr * const tb[])
  54 {
  55         struct nf_acct *nfacct, *matching = NULL;
  56         char *acct_name;
  57         unsigned int size = 0;
  58         u32 flags = 0;
  59
  60         if (!tb[NFACCT_NAME])
  61                 return -EINVAL;
  62
  63         acct_name = nla_data(tb[NFACCT_NAME]);
  64         if (strlen(acct_name) == 0)
  65                 return -EINVAL;
  66
  67         list_for_each_entry(nfacct, &nfnl_acct_list, head) {
  68                 if (strncmp(nfacct->name, acct_name, NFACCT_NAME_MAX) != 0)
  69                         continue;
  70
  71                 if (nlh->nlmsg_flags & NLM_F_EXCL)
  72                         return -EEXIST;
  73
  74                 matching = nfacct;
  75                 break;
  76         }
  77
  78         if (matching) {
  79                 if (nlh->nlmsg_flags & NLM_F_REPLACE) {
  80                         /* reset counters if you request a replacement. */
  81                         atomic64_set(&matching->pkts, 0);
  82                         atomic64_set(&matching->bytes, 0);
  83                         smp_mb__before_atomic();
  84                         /* reset overquota flag if quota is enabled. */
  85                         if ((matching->flags & NFACCT_F_QUOTA))
  86                                 clear_bit(NFACCT_OVERQUOTA_BIT,
  87                                           &matching->flags);
  88                         return 0;
  89                 }
  90                 return -EBUSY;
  91         }
  92
  93         if (tb[NFACCT_FLAGS]) {
  94                 flags = ntohl(nla_get_be32(tb[NFACCT_FLAGS]));
  95                 if (flags & ~NFACCT_F_QUOTA)
  96                         return -EOPNOTSUPP;
  97                 if ((flags & NFACCT_F_QUOTA) == NFACCT_F_QUOTA)
  98                         return -EINVAL;
  99                 if (flags & NFACCT_F_OVERQUOTA)
 100                         return -EINVAL;
 101
 102                 size += sizeof(u64);
 103         }
 104
 105         nfacct = kzalloc(sizeof(struct nf_acct) + size, GFP_KERNEL);
 106         if (nfacct == NULL)
 107                 return -ENOMEM;
 108
 109         if (flags & NFACCT_F_QUOTA) {
 110                 u64 *quota = (u64 *)nfacct->data;
 111
 112                 *quota = be64_to_cpu(nla_get_be64(tb[NFACCT_QUOTA]));
 113                 nfacct->flags = flags;
 114         }
 115
 116         strncpy(nfacct->name, nla_data(tb[NFACCT_NAME]), NFACCT_NAME_MAX);
 117
 118         if (tb[NFACCT_BYTES]) {
 119                 atomic64_set(&nfacct->bytes,
 120                              be64_to_cpu(nla_get_be64(tb[NFACCT_BYTES])));
 121         }
 122         if (tb[NFACCT_PKTS]) {
 123                 atomic64_set(&nfacct->pkts,
 124                              be64_to_cpu(nla_get_be64(tb[NFACCT_PKTS])));
 125         }
 126         atomic_set(&nfacct->refcnt, 1);
 127         list_add_tail_rcu(&nfacct->head, &nfnl_acct_list);
 128         return 0;
 129 }
 130
 131 static int
 132 nfnl_acct_fill_info(struct sk_buff *skb, u32 portid, u32 seq, u32 type,
 133                    int event, struct nf_acct *acct)
 134 {
 135         struct nlmsghdr *nlh;
 136         struct nfgenmsg *nfmsg;
 137         unsigned int flags = portid ? NLM_F_MULTI : 0;
 138         u64 pkts, bytes;
 139         u32 old_flags;
 140
 141         event |= NFNL_SUBSYS_ACCT << 8;
 142         nlh = nlmsg_put(skb, portid, seq, event, sizeof(*nfmsg), flags);
 143         if (nlh == NULL)
 144                 goto nlmsg_failure;
 145
 146         nfmsg = nlmsg_data(nlh);
 147         nfmsg->nfgen_family = AF_UNSPEC;
 148         nfmsg->version = NFNETLINK_V0;
 149         nfmsg->res_id = 0;
 150
 151         if (nla_put_string(skb, NFACCT_NAME, acct->name))
 152                 goto nla_put_failure;
 153
 154         old_flags = acct->flags;
 155         if (type == NFNL_MSG_ACCT_GET_CTRZERO) {
 156                 pkts = atomic64_xchg(&acct->pkts, 0);
 157                 bytes = atomic64_xchg(&acct->bytes, 0);
 158                 smp_mb__before_atomic();
 159                 if (acct->flags & NFACCT_F_QUOTA)
 160                         clear_bit(NFACCT_OVERQUOTA_BIT, &acct->flags);
 161         } else {
 162                 pkts = atomic64_read(&acct->pkts);
 163                 bytes = atomic64_read(&acct->bytes);
 164         }
 165         if (nla_put_be64(skb, NFACCT_PKTS, cpu_to_be64(pkts)) ||
 166             nla_put_be64(skb, NFACCT_BYTES, cpu_to_be64(bytes)) ||
 167             nla_put_be32(skb, NFACCT_USE, htonl(atomic_read(&acct->refcnt))))
 168                 goto nla_put_failure;
 169         if (acct->flags & NFACCT_F_QUOTA) {
 170                 u64 *quota = (u64 *)acct->data;
 171
 172                 if (nla_put_be32(skb, NFACCT_FLAGS, htonl(old_flags)) ||
 173                     nla_put_be64(skb, NFACCT_QUOTA, cpu_to_be64(*quota)))
 174                         goto nla_put_failure;
 175         }
 176         nlmsg_end(skb, nlh);
 177         return skb->len;
 178
 179 nlmsg_failure:
 180 nla_put_failure:
 181         nlmsg_cancel(skb, nlh);
 182         return -1;
 183 }
 184
 185 static int
 186 nfnl_acct_dump(struct sk_buff *skb, struct netlink_callback *cb)
 187 {
 188         struct nf_acct *cur, *last;
 189         const struct nfacct_filter *filter = cb->data;
 190
 191         if (cb->args[2])
 192                 return 0;
 193
 194         last = (struct nf_acct *)cb->args[1];
 195         if (cb->args[1])
 196                 cb->args[1] = 0;
 197
 198         rcu_read_lock();
 199         list_for_each_entry_rcu(cur, &nfnl_acct_list, head) {
 200                 if (last) {
 201                         if (cur != last)
 202                                 continue;
 203
 204                         last = NULL;
 205                 }
 206
 207                 if (filter && (cur->flags & filter->mask) != filter->value)
 208                         continue;
 209
 210                 if (nfnl_acct_fill_info(skb, NETLINK_CB(cb->skb).portid,
 211                                        cb->nlh->nlmsg_seq,
 212                                        NFNL_MSG_TYPE(cb->nlh->nlmsg_type),
 213                                        NFNL_MSG_ACCT_NEW, cur) < 0) {
 214                         cb->args[1] = (unsigned long)cur;
 215                         break;
 216                 }
 217         }
 218         if (!cb->args[1])
 219                 cb->args[2] = 1;
 220         rcu_read_unlock();
 221         return skb->len;
 222 }
 223
 224 static int nfnl_acct_done(struct netlink_callback *cb)
 225 {
 226         kfree(cb->data);
 227         return 0;
 228 }
 229
 230 static const struct nla_policy filter_policy[NFACCT_FILTER_MAX + 1] = {
 231         [NFACCT_FILTER_MASK]    = { .type = NLA_U32 },
 232         [NFACCT_FILTER_VALUE]   = { .type = NLA_U32 },
 233 };
 234
 235 static struct nfacct_filter *
 236 nfacct_filter_alloc(const struct nlattr * const attr)
 237 {
 238         struct nfacct_filter *filter;
 239         struct nlattr *tb[NFACCT_FILTER_MAX + 1];
 240         int err;
 241
 242         err = nla_parse_nested(tb, NFACCT_FILTER_MAX, attr, filter_policy);
 243         if (err < 0)
 244                 return ERR_PTR(err);
 245
 246         filter = kzalloc(sizeof(struct nfacct_filter), GFP_KERNEL);
 247         if (!filter)
 248                 return ERR_PTR(-ENOMEM);
 249
 250         filter->mask = ntohl(nla_get_be32(tb[NFACCT_FILTER_MASK]));
 251         filter->value = ntohl(nla_get_be32(tb[NFACCT_FILTER_VALUE]));
 252
 253         return filter;
 254 }
 255
 256 static int
 257 nfnl_acct_get(struct sock *nfnl, struct sk_buff *skb,
 258              const struct nlmsghdr *nlh, const struct nlattr * const tb[])
 259 {
 260         int ret = -ENOENT;
 261         struct nf_acct *cur;
 262         char *acct_name;
 263
 264         if (nlh->nlmsg_flags & NLM_F_DUMP) {
 265                 struct netlink_dump_control c = {
 266                         .dump = nfnl_acct_dump,
 267                         .done = nfnl_acct_done,
 268                 };
 269
 270                 if (tb[NFACCT_FILTER]) {
 271                         struct nfacct_filter *filter;
 272
 273                         filter = nfacct_filter_alloc(tb[NFACCT_FILTER]);
 274                         if (IS_ERR(filter))
 275                                 return PTR_ERR(filter);
 276
 277                         c.data = filter;
 278                 }
 279                 return netlink_dump_start(nfnl, skb, nlh, &c);
 280         }
 281
 282         if (!tb[NFACCT_NAME])
 283                 return -EINVAL;
 284         acct_name = nla_data(tb[NFACCT_NAME]);
 285
 286         list_for_each_entry(cur, &nfnl_acct_list, head) {
 287                 struct sk_buff *skb2;
 288
 289                 if (strncmp(cur->name, acct_name, NFACCT_NAME_MAX)!= 0)
 290                         continue;
 291
 292                 skb2 = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
 293                 if (skb2 == NULL) {
 294                         ret = -ENOMEM;
 295                         break;
 296                 }
 297
 298                 ret = nfnl_acct_fill_info(skb2, NETLINK_CB(skb).portid,
 299                                          nlh->nlmsg_seq,
 300                                          NFNL_MSG_TYPE(nlh->nlmsg_type),
 301                                          NFNL_MSG_ACCT_NEW, cur);
 302                 if (ret <= 0) {
 303                         kfree_skb(skb2);
 304                         break;
 305                 }
 306                 ret = netlink_unicast(nfnl, skb2, NETLINK_CB(skb).portid,
 307                                         MSG_DONTWAIT);
 308                 if (ret > 0)
 309                         ret = 0;
 310
 311                 /* this avoids a loop in nfnetlink. */
 312                 return ret == -EAGAIN ? -ENOBUFS : ret;
 313         }
 314         return ret;
 315 }
 316
 317 /* try to delete object, fail if it is still in use. */
 318 static int nfnl_acct_try_del(struct nf_acct *cur)
 319 {
 320         int ret = 0;
 321
 322         /* we want to avoid races with nfnl_acct_find_get. */
 323         if (atomic_dec_and_test(&cur->refcnt)) {
 324                 /* We are protected by nfnl mutex. */
 325                 list_del_rcu(&cur->head);
 326                 kfree_rcu(cur, rcu_head);
 327         } else {
 328                 /* still in use, restore reference counter. */
 329                 atomic_inc(&cur->refcnt);
 330                 ret = -EBUSY;
 331         }
 332         return ret;
 333 }
 334
 335 static int
 336 nfnl_acct_del(struct sock *nfnl, struct sk_buff *skb,
 337              const struct nlmsghdr *nlh, const struct nlattr * const tb[])
 338 {
 339         char *acct_name;
 340         struct nf_acct *cur;
 341         int ret = -ENOENT;
 342
 343         if (!tb[NFACCT_NAME]) {
 344                 list_for_each_entry(cur, &nfnl_acct_list, head)
 345                         nfnl_acct_try_del(cur);
 346
 347                 return 0;
 348         }
 349         acct_name = nla_data(tb[NFACCT_NAME]);
 350
 351         list_for_each_entry(cur, &nfnl_acct_list, head) {
 352                 if (strncmp(cur->name, acct_name, NFACCT_NAME_MAX) != 0)
 353                         continue;
 354
 355                 ret = nfnl_acct_try_del(cur);
 356                 if (ret < 0)
 357                         return ret;
 358
 359                 break;
 360         }
 361         return ret;
 362 }
 363
 364 static const struct nla_policy nfnl_acct_policy[NFACCT_MAX+1] = {
 365         [NFACCT_NAME] = { .type = NLA_NUL_STRING, .len = NFACCT_NAME_MAX-1 },
 366         [NFACCT_BYTES] = { .type = NLA_U64 },
 367         [NFACCT_PKTS] = { .type = NLA_U64 },
 368         [NFACCT_FLAGS] = { .type = NLA_U32 },
 369         [NFACCT_QUOTA] = { .type = NLA_U64 },
 370         [NFACCT_FILTER] = {.type = NLA_NESTED },
 371 };
 372
 373 static const struct nfnl_callback nfnl_acct_cb[NFNL_MSG_ACCT_MAX] = {
 374         [NFNL_MSG_ACCT_NEW]             = { .call = nfnl_acct_new,
 375                                             .attr_count = NFACCT_MAX,
 376                                             .policy = nfnl_acct_policy },
 377         [NFNL_MSG_ACCT_GET]             = { .call = nfnl_acct_get,
 378                                             .attr_count = NFACCT_MAX,
 379                                             .policy = nfnl_acct_policy },
 380         [NFNL_MSG_ACCT_GET_CTRZERO]     = { .call = nfnl_acct_get,
 381                                             .attr_count = NFACCT_MAX,
 382                                             .policy = nfnl_acct_policy },
 383         [NFNL_MSG_ACCT_DEL]             = { .call = nfnl_acct_del,
 384                                             .attr_count = NFACCT_MAX,
 385                                             .policy = nfnl_acct_policy },
 386 };
 387
 388 static const struct nfnetlink_subsystem nfnl_acct_subsys = {
 389         .name                           = "acct",
 390         .subsys_id                      = NFNL_SUBSYS_ACCT,
 391         .cb_count                       = NFNL_MSG_ACCT_MAX,
 392         .cb                             = nfnl_acct_cb,
 393 };
 394
 395 MODULE_ALIAS_NFNL_SUBSYS(NFNL_SUBSYS_ACCT);
 396
 397 struct nf_acct *nfnl_acct_find_get(const char *acct_name)
 398 {
 399         struct nf_acct *cur, *acct = NULL;
 400
 401         rcu_read_lock();
 402         list_for_each_entry_rcu(cur, &nfnl_acct_list, head) {
 403                 if (strncmp(cur->name, acct_name, NFACCT_NAME_MAX)!= 0)
 404                         continue;
 405
 406                 if (!try_module_get(THIS_MODULE))
 407                         goto err;
 408
 409                 if (!atomic_inc_not_zero(&cur->refcnt)) {
 410                         module_put(THIS_MODULE);
 411                         goto err;
 412                 }
 413
 414                 acct = cur;
 415                 break;
 416         }
 417 err:
 418         rcu_read_unlock();
 419         return acct;
 420 }
 421 EXPORT_SYMBOL_GPL(nfnl_acct_find_get);
 422
 423 void nfnl_acct_put(struct nf_acct *acct)
 424 {
 425         atomic_dec(&acct->refcnt);
 426         module_put(THIS_MODULE);
 427 }
 428 EXPORT_SYMBOL_GPL(nfnl_acct_put);
 429
 430 void nfnl_acct_update(const struct sk_buff *skb, struct nf_acct *nfacct)
 431 {
 432         atomic64_inc(&nfacct->pkts);
 433         atomic64_add(skb->len, &nfacct->bytes);
 434 }
 435 EXPORT_SYMBOL_GPL(nfnl_acct_update);
 436
 437 static void nfnl_overquota_report(struct nf_acct *nfacct)
 438 {
 439         int ret;
 440         struct sk_buff *skb;
 441
 442         skb = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_ATOMIC);
 443         if (skb == NULL)
 444                 return;
 445
 446         ret = nfnl_acct_fill_info(skb, 0, 0, NFNL_MSG_ACCT_OVERQUOTA, 0,
 447                                   nfacct);
 448         if (ret <= 0) {
 449                 kfree_skb(skb);
 450                 return;
 451         }
 452         netlink_broadcast(init_net.nfnl, skb, 0, NFNLGRP_ACCT_QUOTA,
 453                           GFP_ATOMIC);
 454 }
 455
 456 int nfnl_acct_overquota(const struct sk_buff *skb, struct nf_acct *nfacct)
 457 {
 458         u64 now;
 459         u64 *quota;
 460         int ret = NFACCT_UNDERQUOTA;
 461
 462         /* no place here if we don't have a quota */
 463         if (!(nfacct->flags & NFACCT_F_QUOTA))
 464                 return NFACCT_NO_QUOTA;
 465
 466         quota = (u64 *)nfacct->data;
 467         now = (nfacct->flags & NFACCT_F_QUOTA_PKTS) ?
 468                atomic64_read(&nfacct->pkts) : atomic64_read(&nfacct->bytes);
 469
 470         ret = now > *quota;
 471
 472         if (now >= *quota &&
 473             !test_and_set_bit(NFACCT_OVERQUOTA_BIT, &nfacct->flags)) {
 474                 nfnl_overquota_report(nfacct);
 475         }
 476
 477         return ret;
 478 }
 479 EXPORT_SYMBOL_GPL(nfnl_acct_overquota);
 480
 481 static int __init nfnl_acct_init(void)
 482 {
 483         int ret;
 484
 485         pr_info("nfnl_acct: registering with nfnetlink.\n");
 486         ret = nfnetlink_subsys_register(&nfnl_acct_subsys);
 487         if (ret < 0) {
 488                 pr_err("nfnl_acct_init: cannot register with nfnetlink.\n");
 489                 goto err_out;
 490         }
 491         return 0;
 492 err_out:
 493         return ret;
 494 }
 495
 496 static void __exit nfnl_acct_exit(void)
 497 {
 498         struct nf_acct *cur, *tmp;
 499
 500         pr_info("nfnl_acct: unregistering from nfnetlink.\n");
 501         nfnetlink_subsys_unregister(&nfnl_acct_subsys);
 502
 503         list_for_each_entry_safe(cur, tmp, &nfnl_acct_list, head) {
 504                 list_del_rcu(&cur->head);
 505                 /* We are sure that our objects have no clients at this point,
 506                  * it's safe to release them all without checking refcnt. */
 507                 kfree_rcu(cur, rcu_head);
 508         }
 509 }
 510
 511 module_init(nfnl_acct_init);
 512 module_exit(nfnl_acct_exit);