net/netfilter/nfnetlink_acct.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * (C) 2011 Pablo Neira Ayuso <pablo@netfilter.org>
   4  * (C) 2011 Intra2net AG <https://www.intra2net.com>
   5  */
   6 #include <linux/init.h>
   7 #include <linux/module.h>
   8 #include <linux/kernel.h>
   9 #include <linux/skbuff.h>
  10 #include <linux/atomic.h>
  11 #include <linux/refcount.h>
  12 #include <linux/netlink.h>
  13 #include <linux/rculist.h>
  14 #include <linux/slab.h>
  15 #include <linux/types.h>
  16 #include <linux/errno.h>
  17 #include <net/netlink.h>
  18 #include <net/sock.h>
  19 #include <net/netns/generic.h>
  20
  21 #include <linux/netfilter.h>
  22 #include <linux/netfilter/nfnetlink.h>
  23 #include <linux/netfilter/nfnetlink_acct.h>
  24
  25 MODULE_LICENSE("GPL");
  26 MODULE_AUTHOR("Pablo Neira Ayuso <pablo@netfilter.org>");
  27 MODULE_DESCRIPTION("nfacct: Extended Netfilter accounting infrastructure");
  28
  29 struct nf_acct {
  30         atomic64_t              pkts;
  31         atomic64_t              bytes;
  32         unsigned long           flags;
  33         struct list_head        head;
  34         refcount_t              refcnt;
  35         char                    name[NFACCT_NAME_MAX];
  36         struct rcu_head         rcu_head;
  37         char                    data[];
  38 };
  39
  40 struct nfacct_filter {
  41         u32 value;
  42         u32 mask;
  43 };
  44
  45 struct nfnl_acct_net {
  46         struct list_head        nfnl_acct_list;
  47 };
  48
  49 static unsigned int nfnl_acct_net_id __read_mostly;
  50
  51 static inline struct nfnl_acct_net *nfnl_acct_pernet(struct net *net)
  52 {
  53         return net_generic(net, nfnl_acct_net_id);
  54 }
  55
  56 #define NFACCT_F_QUOTA (NFACCT_F_QUOTA_PKTS | NFACCT_F_QUOTA_BYTES)
  57 #define NFACCT_OVERQUOTA_BIT    2       /* NFACCT_F_OVERQUOTA */
  58
  59 static int nfnl_acct_new(struct sk_buff *skb, const struct nfnl_info *info,
  60                          const struct nlattr * const tb[])
  61 {
  62         struct nfnl_acct_net *nfnl_acct_net = nfnl_acct_pernet(info->net);
  63         struct nf_acct *nfacct, *matching = NULL;
  64         unsigned int size = 0;
  65         char *acct_name;
  66         u32 flags = 0;
  67
  68         if (!tb[NFACCT_NAME])
  69                 return -EINVAL;
  70
  71         acct_name = nla_data(tb[NFACCT_NAME]);
  72         if (strlen(acct_name) == 0)
  73                 return -EINVAL;
  74
  75         list_for_each_entry(nfacct, &nfnl_acct_net->nfnl_acct_list, head) {
  76                 if (strncmp(nfacct->name, acct_name, NFACCT_NAME_MAX) != 0)
  77                         continue;
  78
  79                 if (info->nlh->nlmsg_flags & NLM_F_EXCL)
  80                         return -EEXIST;
  81
  82                 matching = nfacct;
  83                 break;
  84         }
  85
  86         if (matching) {
  87                 if (info->nlh->nlmsg_flags & NLM_F_REPLACE) {
  88                         /* reset counters if you request a replacement. */
  89                         atomic64_set(&matching->pkts, 0);
  90                         atomic64_set(&matching->bytes, 0);
  91                         smp_mb__before_atomic();
  92                         /* reset overquota flag if quota is enabled. */
  93                         if ((matching->flags & NFACCT_F_QUOTA))
  94                                 clear_bit(NFACCT_OVERQUOTA_BIT,
  95                                           &matching->flags);
  96                         return 0;
  97                 }
  98                 return -EBUSY;
  99         }
 100
 101         if (tb[NFACCT_FLAGS]) {
 102                 flags = ntohl(nla_get_be32(tb[NFACCT_FLAGS]));
 103                 if (flags & ~NFACCT_F_QUOTA)
 104                         return -EOPNOTSUPP;
 105                 if ((flags & NFACCT_F_QUOTA) == NFACCT_F_QUOTA)
 106                         return -EINVAL;
 107                 if (flags & NFACCT_F_OVERQUOTA)
 108                         return -EINVAL;
 109                 if ((flags & NFACCT_F_QUOTA) && !tb[NFACCT_QUOTA])
 110                         return -EINVAL;
 111
 112                 size += sizeof(u64);
 113         }
 114
 115         nfacct = kzalloc(sizeof(struct nf_acct) + size, GFP_KERNEL);
 116         if (nfacct == NULL)
 117                 return -ENOMEM;
 118
 119         if (flags & NFACCT_F_QUOTA) {
 120                 u64 *quota = (u64 *)nfacct->data;
 121
 122                 *quota = be64_to_cpu(nla_get_be64(tb[NFACCT_QUOTA]));
 123                 nfacct->flags = flags;
 124         }
 125
 126         nla_strscpy(nfacct->name, tb[NFACCT_NAME], NFACCT_NAME_MAX);
 127
 128         if (tb[NFACCT_BYTES]) {
 129                 atomic64_set(&nfacct->bytes,
 130                              be64_to_cpu(nla_get_be64(tb[NFACCT_BYTES])));
 131         }
 132         if (tb[NFACCT_PKTS]) {
 133                 atomic64_set(&nfacct->pkts,
 134                              be64_to_cpu(nla_get_be64(tb[NFACCT_PKTS])));
 135         }
 136         refcount_set(&nfacct->refcnt, 1);
 137         list_add_tail_rcu(&nfacct->head, &nfnl_acct_net->nfnl_acct_list);
 138         return 0;
 139 }
 140
 141 static int
 142 nfnl_acct_fill_info(struct sk_buff *skb, u32 portid, u32 seq, u32 type,
 143                    int event, struct nf_acct *acct)
 144 {
 145         struct nlmsghdr *nlh;
 146         unsigned int flags = portid ? NLM_F_MULTI : 0;
 147         u64 pkts, bytes;
 148         u32 old_flags;
 149
 150         event = nfnl_msg_type(NFNL_SUBSYS_ACCT, event);
 151         nlh = nfnl_msg_put(skb, portid, seq, event, flags, AF_UNSPEC,
 152                            NFNETLINK_V0, 0);
 153         if (!nlh)
 154                 goto nlmsg_failure;
 155
 156         if (nla_put_string(skb, NFACCT_NAME, acct->name))
 157                 goto nla_put_failure;
 158
 159         old_flags = acct->flags;
 160         if (type == NFNL_MSG_ACCT_GET_CTRZERO) {
 161                 pkts = atomic64_xchg(&acct->pkts, 0);
 162                 bytes = atomic64_xchg(&acct->bytes, 0);
 163                 smp_mb__before_atomic();
 164                 if (acct->flags & NFACCT_F_QUOTA)
 165                         clear_bit(NFACCT_OVERQUOTA_BIT, &acct->flags);
 166         } else {
 167                 pkts = atomic64_read(&acct->pkts);
 168                 bytes = atomic64_read(&acct->bytes);
 169         }
 170         if (nla_put_be64(skb, NFACCT_PKTS, cpu_to_be64(pkts),
 171                          NFACCT_PAD) ||
 172             nla_put_be64(skb, NFACCT_BYTES, cpu_to_be64(bytes),
 173                          NFACCT_PAD) ||
 174             nla_put_be32(skb, NFACCT_USE, htonl(refcount_read(&acct->refcnt))))
 175                 goto nla_put_failure;
 176         if (acct->flags & NFACCT_F_QUOTA) {
 177                 u64 *quota = (u64 *)acct->data;
 178
 179                 if (nla_put_be32(skb, NFACCT_FLAGS, htonl(old_flags)) ||
 180                     nla_put_be64(skb, NFACCT_QUOTA, cpu_to_be64(*quota),
 181                                  NFACCT_PAD))
 182                         goto nla_put_failure;
 183         }
 184         nlmsg_end(skb, nlh);
 185         return skb->len;
 186
 187 nlmsg_failure:
 188 nla_put_failure:
 189         nlmsg_cancel(skb, nlh);
 190         return -1;
 191 }
 192
 193 static int
 194 nfnl_acct_dump(struct sk_buff *skb, struct netlink_callback *cb)
 195 {
 196         struct net *net = sock_net(skb->sk);
 197         struct nfnl_acct_net *nfnl_acct_net = nfnl_acct_pernet(net);
 198         struct nf_acct *cur, *last;
 199         const struct nfacct_filter *filter = cb->data;
 200
 201         if (cb->args[2])
 202                 return 0;
 203
 204         last = (struct nf_acct *)cb->args[1];
 205         if (cb->args[1])
 206                 cb->args[1] = 0;
 207
 208         rcu_read_lock();
 209         list_for_each_entry_rcu(cur, &nfnl_acct_net->nfnl_acct_list, head) {
 210                 if (last) {
 211                         if (cur != last)
 212                                 continue;
 213
 214                         last = NULL;
 215                 }
 216
 217                 if (filter && (cur->flags & filter->mask) != filter->value)
 218                         continue;
 219
 220                 if (nfnl_acct_fill_info(skb, NETLINK_CB(cb->skb).portid,
 221                                        cb->nlh->nlmsg_seq,
 222                                        NFNL_MSG_TYPE(cb->nlh->nlmsg_type),
 223                                        NFNL_MSG_ACCT_NEW, cur) < 0) {
 224                         cb->args[1] = (unsigned long)cur;
 225                         break;
 226                 }
 227         }
 228         if (!cb->args[1])
 229                 cb->args[2] = 1;
 230         rcu_read_unlock();
 231         return skb->len;
 232 }
 233
 234 static int nfnl_acct_done(struct netlink_callback *cb)
 235 {
 236         kfree(cb->data);
 237         return 0;
 238 }
 239
 240 static const struct nla_policy filter_policy[NFACCT_FILTER_MAX + 1] = {
 241         [NFACCT_FILTER_MASK]    = { .type = NLA_U32 },
 242         [NFACCT_FILTER_VALUE]   = { .type = NLA_U32 },
 243 };
 244
 245 static int nfnl_acct_start(struct netlink_callback *cb)
 246 {
 247         const struct nlattr *const attr = cb->data;
 248         struct nlattr *tb[NFACCT_FILTER_MAX + 1];
 249         struct nfacct_filter *filter;
 250         int err;
 251
 252         if (!attr)
 253                 return 0;
 254
 255         err = nla_parse_nested_deprecated(tb, NFACCT_FILTER_MAX, attr,
 256                                           filter_policy, NULL);
 257         if (err < 0)
 258                 return err;
 259
 260         if (!tb[NFACCT_FILTER_MASK] || !tb[NFACCT_FILTER_VALUE])
 261                 return -EINVAL;
 262
 263         filter = kzalloc(sizeof(struct nfacct_filter), GFP_KERNEL);
 264         if (!filter)
 265                 return -ENOMEM;
 266
 267         filter->mask = ntohl(nla_get_be32(tb[NFACCT_FILTER_MASK]));
 268         filter->value = ntohl(nla_get_be32(tb[NFACCT_FILTER_VALUE]));
 269         cb->data = filter;
 270
 271         return 0;
 272 }
 273
 274 static int nfnl_acct_get(struct sk_buff *skb, const struct nfnl_info *info,
 275                          const struct nlattr * const tb[])
 276 {
 277         struct nfnl_acct_net *nfnl_acct_net = nfnl_acct_pernet(info->net);
 278         int ret = -ENOENT;
 279         struct nf_acct *cur;
 280         char *acct_name;
 281
 282         if (info->nlh->nlmsg_flags & NLM_F_DUMP) {
 283                 struct netlink_dump_control c = {
 284                         .dump = nfnl_acct_dump,
 285                         .start = nfnl_acct_start,
 286                         .done = nfnl_acct_done,
 287                         .data = (void *)tb[NFACCT_FILTER],
 288                 };
 289
 290                 return netlink_dump_start(info->sk, skb, info->nlh, &c);
 291         }
 292
 293         if (!tb[NFACCT_NAME])
 294                 return -EINVAL;
 295         acct_name = nla_data(tb[NFACCT_NAME]);
 296
 297         list_for_each_entry(cur, &nfnl_acct_net->nfnl_acct_list, head) {
 298                 struct sk_buff *skb2;
 299
 300                 if (strncmp(cur->name, acct_name, NFACCT_NAME_MAX)!= 0)
 301                         continue;
 302
 303                 skb2 = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
 304                 if (skb2 == NULL) {
 305                         ret = -ENOMEM;
 306                         break;
 307                 }
 308
 309                 ret = nfnl_acct_fill_info(skb2, NETLINK_CB(skb).portid,
 310                                           info->nlh->nlmsg_seq,
 311                                           NFNL_MSG_TYPE(info->nlh->nlmsg_type),
 312                                           NFNL_MSG_ACCT_NEW, cur);
 313                 if (ret <= 0) {
 314                         kfree_skb(skb2);
 315                         break;
 316                 }
 317                 ret = netlink_unicast(info->sk, skb2, NETLINK_CB(skb).portid,
 318                                       MSG_DONTWAIT);
 319                 if (ret > 0)
 320                         ret = 0;
 321
 322                 /* this avoids a loop in nfnetlink. */
 323                 return ret == -EAGAIN ? -ENOBUFS : ret;
 324         }
 325         return ret;
 326 }
 327
 328 /* try to delete object, fail if it is still in use. */
 329 static int nfnl_acct_try_del(struct nf_acct *cur)
 330 {
 331         int ret = 0;
 332
 333         /* We want to avoid races with nfnl_acct_put. So only when the current
 334          * refcnt is 1, we decrease it to 0.
 335          */
 336         if (refcount_dec_if_one(&cur->refcnt)) {
 337                 /* We are protected by nfnl mutex. */
 338                 list_del_rcu(&cur->head);
 339                 kfree_rcu(cur, rcu_head);
 340         } else {
 341                 ret = -EBUSY;
 342         }
 343         return ret;
 344 }
 345
 346 static int nfnl_acct_del(struct sk_buff *skb, const struct nfnl_info *info,
 347                          const struct nlattr * const tb[])
 348 {
 349         struct nfnl_acct_net *nfnl_acct_net = nfnl_acct_pernet(info->net);
 350         struct nf_acct *cur, *tmp;
 351         int ret = -ENOENT;
 352         char *acct_name;
 353
 354         if (!tb[NFACCT_NAME]) {
 355                 list_for_each_entry_safe(cur, tmp, &nfnl_acct_net->nfnl_acct_list, head)
 356                         nfnl_acct_try_del(cur);
 357
 358                 return 0;
 359         }
 360         acct_name = nla_data(tb[NFACCT_NAME]);
 361
 362         list_for_each_entry(cur, &nfnl_acct_net->nfnl_acct_list, head) {
 363                 if (strncmp(cur->name, acct_name, NFACCT_NAME_MAX) != 0)
 364                         continue;
 365
 366                 ret = nfnl_acct_try_del(cur);
 367                 if (ret < 0)
 368                         return ret;
 369
 370                 break;
 371         }
 372         return ret;
 373 }
 374
 375 static const struct nla_policy nfnl_acct_policy[NFACCT_MAX+1] = {
 376         [NFACCT_NAME] = { .type = NLA_NUL_STRING, .len = NFACCT_NAME_MAX-1 },
 377         [NFACCT_BYTES] = { .type = NLA_U64 },
 378         [NFACCT_PKTS] = { .type = NLA_U64 },
 379         [NFACCT_FLAGS] = { .type = NLA_U32 },
 380         [NFACCT_QUOTA] = { .type = NLA_U64 },
 381         [NFACCT_FILTER] = {.type = NLA_NESTED },
 382 };
 383
 384 static const struct nfnl_callback nfnl_acct_cb[NFNL_MSG_ACCT_MAX] = {
 385         [NFNL_MSG_ACCT_NEW] = {
 386                 .call           = nfnl_acct_new,
 387                 .type           = NFNL_CB_MUTEX,
 388                 .attr_count     = NFACCT_MAX,
 389                 .policy         = nfnl_acct_policy
 390         },
 391         [NFNL_MSG_ACCT_GET] = {
 392                 .call           = nfnl_acct_get,
 393                 .type           = NFNL_CB_MUTEX,
 394                 .attr_count     = NFACCT_MAX,
 395                 .policy         = nfnl_acct_policy
 396         },
 397         [NFNL_MSG_ACCT_GET_CTRZERO] = {
 398                 .call           = nfnl_acct_get,
 399                 .type           = NFNL_CB_MUTEX,
 400                 .attr_count     = NFACCT_MAX,
 401                 .policy         = nfnl_acct_policy
 402         },
 403         [NFNL_MSG_ACCT_DEL] = {
 404                 .call           = nfnl_acct_del,
 405                 .type           = NFNL_CB_MUTEX,
 406                 .attr_count     = NFACCT_MAX,
 407                 .policy         = nfnl_acct_policy
 408         },
 409 };
 410
 411 static const struct nfnetlink_subsystem nfnl_acct_subsys = {
 412         .name                           = "acct",
 413         .subsys_id                      = NFNL_SUBSYS_ACCT,
 414         .cb_count                       = NFNL_MSG_ACCT_MAX,
 415         .cb                             = nfnl_acct_cb,
 416 };
 417
 418 MODULE_ALIAS_NFNL_SUBSYS(NFNL_SUBSYS_ACCT);
 419
 420 struct nf_acct *nfnl_acct_find_get(struct net *net, const char *acct_name)
 421 {
 422         struct nfnl_acct_net *nfnl_acct_net = nfnl_acct_pernet(net);
 423         struct nf_acct *cur, *acct = NULL;
 424
 425         rcu_read_lock();
 426         list_for_each_entry_rcu(cur, &nfnl_acct_net->nfnl_acct_list, head) {
 427                 if (strncmp(cur->name, acct_name, NFACCT_NAME_MAX)!= 0)
 428                         continue;
 429
 430                 if (!try_module_get(THIS_MODULE))
 431                         goto err;
 432
 433                 if (!refcount_inc_not_zero(&cur->refcnt)) {
 434                         module_put(THIS_MODULE);
 435                         goto err;
 436                 }
 437
 438                 acct = cur;
 439                 break;
 440         }
 441 err:
 442         rcu_read_unlock();
 443         return acct;
 444 }
 445 EXPORT_SYMBOL_GPL(nfnl_acct_find_get);
 446
 447 void nfnl_acct_put(struct nf_acct *acct)
 448 {
 449         if (refcount_dec_and_test(&acct->refcnt))
 450                 kfree_rcu(acct, rcu_head);
 451
 452         module_put(THIS_MODULE);
 453 }
 454 EXPORT_SYMBOL_GPL(nfnl_acct_put);
 455
 456 void nfnl_acct_update(const struct sk_buff *skb, struct nf_acct *nfacct)
 457 {
 458         atomic64_inc(&nfacct->pkts);
 459         atomic64_add(skb->len, &nfacct->bytes);
 460 }
 461 EXPORT_SYMBOL_GPL(nfnl_acct_update);
 462
 463 static void nfnl_overquota_report(struct net *net, struct nf_acct *nfacct)
 464 {
 465         int ret;
 466         struct sk_buff *skb;
 467
 468         skb = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_ATOMIC);
 469         if (skb == NULL)
 470                 return;
 471
 472         ret = nfnl_acct_fill_info(skb, 0, 0, NFNL_MSG_ACCT_OVERQUOTA, 0,
 473                                   nfacct);
 474         if (ret <= 0) {
 475                 kfree_skb(skb);
 476                 return;
 477         }
 478         nfnetlink_broadcast(net, skb, 0, NFNLGRP_ACCT_QUOTA, GFP_ATOMIC);
 479 }
 480
 481 int nfnl_acct_overquota(struct net *net, struct nf_acct *nfacct)
 482 {
 483         u64 now;
 484         u64 *quota;
 485         int ret = NFACCT_UNDERQUOTA;
 486
 487         /* no place here if we don't have a quota */
 488         if (!(nfacct->flags & NFACCT_F_QUOTA))
 489                 return NFACCT_NO_QUOTA;
 490
 491         quota = (u64 *)nfacct->data;
 492         now = (nfacct->flags & NFACCT_F_QUOTA_PKTS) ?
 493                atomic64_read(&nfacct->pkts) : atomic64_read(&nfacct->bytes);
 494
 495         ret = now > *quota;
 496
 497         if (now >= *quota &&
 498             !test_and_set_bit(NFACCT_OVERQUOTA_BIT, &nfacct->flags)) {
 499                 nfnl_overquota_report(net, nfacct);
 500         }
 501
 502         return ret;
 503 }
 504 EXPORT_SYMBOL_GPL(nfnl_acct_overquota);
 505
 506 static int __net_init nfnl_acct_net_init(struct net *net)
 507 {
 508         INIT_LIST_HEAD(&nfnl_acct_pernet(net)->nfnl_acct_list);
 509
 510         return 0;
 511 }
 512
 513 static void __net_exit nfnl_acct_net_exit(struct net *net)
 514 {
 515         struct nfnl_acct_net *nfnl_acct_net = nfnl_acct_pernet(net);
 516         struct nf_acct *cur, *tmp;
 517
 518         list_for_each_entry_safe(cur, tmp, &nfnl_acct_net->nfnl_acct_list, head) {
 519                 list_del_rcu(&cur->head);
 520
 521                 if (refcount_dec_and_test(&cur->refcnt))
 522                         kfree_rcu(cur, rcu_head);
 523         }
 524 }
 525
 526 static struct pernet_operations nfnl_acct_ops = {
 527         .init   = nfnl_acct_net_init,
 528         .exit   = nfnl_acct_net_exit,
 529         .id     = &nfnl_acct_net_id,
 530         .size   = sizeof(struct nfnl_acct_net),
 531 };
 532
 533 static int __init nfnl_acct_init(void)
 534 {
 535         int ret;
 536
 537         ret = register_pernet_subsys(&nfnl_acct_ops);
 538         if (ret < 0) {
 539                 pr_err("nfnl_acct_init: failed to register pernet ops\n");
 540                 goto err_out;
 541         }
 542
 543         ret = nfnetlink_subsys_register(&nfnl_acct_subsys);
 544         if (ret < 0) {
 545                 pr_err("nfnl_acct_init: cannot register with nfnetlink.\n");
 546                 goto cleanup_pernet;
 547         }
 548         return 0;
 549
 550 cleanup_pernet:
 551         unregister_pernet_subsys(&nfnl_acct_ops);
 552 err_out:
 553         return ret;
 554 }
 555
 556 static void __exit nfnl_acct_exit(void)
 557 {
 558         nfnetlink_subsys_unregister(&nfnl_acct_subsys);
 559         unregister_pernet_subsys(&nfnl_acct_ops);
 560 }
 561
 562 module_init(nfnl_acct_init);
 563 module_exit(nfnl_acct_exit);